Interference information indicator table for a mobile station located at a cell edge
Abstract
A mobile communication system comprising a mobile station apparatus and a base station apparatus, wherein: said base station apparatus is adapted to divide an uplink channel frequency band into a predetermined number of frequency bands and to create an interference information indicator table showing an interface state with a plurality of magnitude relationships for each of said divided frequency bands, based on the measured quality of the channel for each of said divided frequency bands; said base station apparatus is further adapted to transmit said interference information indicator table to another base station apparatus; and said mobile station apparatus is adapted to perform a data transmission in accordance with an allocation of the transmission resource based on said interference information indicator table.
Term
1.3 yearsto projected expiry
Projected expiry 25 January 2028, counted from filing; an application has no term until it is granted.
- Priority and filed
- Published
- Today
- Projected expiry
5 claims: 3 independent, 2 dependent
- 1ES 2 393 767 T3 REIVINDICACIONES 1. Un sistema de comunicación móvil que comprende un aparato de estación móvil y un aparato de estación base, en donde:dicho aparato de estación base se adapta para dividir una banda de frecuencia de canal de enlace ascendente en un número predeterminado de bandas de frecuencia y para crear una tabla indicadora de información de interferencia que muestra un estado de interfaz con una pluralidad de relaciones de magnitud para cada una de dichas bandas de frecuencia divididas, con base en la calidad medida del canal para cada una de dichas bandas de frecuencia divididas;dicho aparato de estación base se adapta adicionalmente para transmitir dicha tabla indicadora de información de interferencia a otro aparato de estación base;y dicho aparato de estación móvil se adapta para realizar una transmisión de datos de acuerdo con una asignación del recurso de transmisión con base en dicha tabla indicadora de información de interferencia.
- 2El sistema de comunicación móvil de acuerdo con la reivindicación 1, en donde:el aparato de estación base se adapta para crear dicha tabla indicadora de información de interferencia utilizando SIR (Relación de Interferencia a Señal), SINR (Relación de Ruido más Interferencia a la Señal), o CIR (Relación de Interferencia a Portador) en un canal de enlace ascendente como dicha calidad del canal.
- 3El sistema de comunicación móvil de acuerdo con la reivindicación 1, en donde:el aparato de estación base se adapta para encontrar dicha calidad del canal con base en la medición de la señal piloto y/o la demodulación de la señal piloto recibida desde dicho aparato de estación móvil.
- 4Un aparato de estación base adaptado para comunicar con un aparato de estación móvil, en donde:dicho aparato de estación base se adapta para dividir una banda de frecuencia de canal de enlace ascendente en un número predeterminado de bandas de frecuencia y para crear una tabla indicadora de información de interferencia que muestra un estado de interfaz con una pluralidad de relaciones de magnitud para cada una de dichas bandas de frecuencia divididas, con base en la calidad medida del canal para cada una de dichas bandas de frecuencia divididas;dicho aparato de estación base se adapta adicionalmente para transmitir dicha tabla indicadora de información de interferencia a otro aparato de estación base.
- 5Un método de comunicación de un aparato de estación base que comunica con un aparato de estación móvil, que comprende por lo menos las etapas de;dividir una banda de frecuencia de canal de enlace ascendente en un número predeterminado de bandas de frecuencia;crear una tabla indicadora de información de interferencia que muestra un estado de interfaz con una pluralidad de relaciones de magnitud para cada una de dichas bandas de frecuencia divididas, con base en la calidad medida del canal para cada una de dichas bandas de frecuencia divididas;y transmitir dicha tabla indicadora de información de interferencia a otro aparato de estación base.
Independent claims5
273 paragraphs in 11 sections, as filed
ES 2 393 767 T3
DESCRIPTION
Exchange an interface table between base stations
Technical Field
The present invention relates to a technique for establishing data communication by making use of a plurality of subcarriers and, more particularly, to a mobile communication system, a base station apparatus, and a communication method that realizes performance improvements. of the entire system by reducing inter-cell interference.
Background Technique
At present, Evolved Universal Terrestrial Radio Access (hereinafter referred to as EUTRA) for the purpose of increasing communication speed by introducing part of a technique that has been discussed for the frequency band of fourth generation in the third generation frequency band is discussed by the 3GPP (3rd Generation Partnership Project) standardization group (for example, referred to as non-patent document 1).
The OFDMA (Orthogonal Frequency Division Multiplexing Access) scheme which is robust against multipath interference and suitable for high speed transmission has been determined to be adopted as a communication scheme for EUTRA. Additionally, in order to improve the uplink performance of a mobile station over a cell edge and to increase the capacity of the entire cell, the introduction of a technique, called as an interference coordination, for the purpose of suppressing the Inter-cell interference in an uplink transmission is widely discussed (eg, with reference to non-patent document 1).
As an interference coordination, a plurality of methods have been proposed. As one of these, a method has been proposed, in which the frequency band that can be used in a system is divided into several parts, the mobile stations are divided into several groups based on the transmission power, received quality of the link downstream, etc., each group is associated with a split frequency band, and a mobile station makes only one transmission in a corresponding frequency band (eg, referring to non-patent document 2). Non-patent document 2 has introduced a method to improve transmission data performance without increasing an amount of interference between uplink cells by setting the highest target quality of base station receive power in the corresponding frequency band. when the distance between the mobile station and the base station becomes smaller.
On the other hand, another method has been proposed, in which the amount of interference between the uplink cells is suppressed by just adjusting the transmit power without dividing a frequency band (for example, with reference to document non-patent 3 and non-patent document 4). Non-patent document 3 has introduced a transmission power control method to suppress inter-cell interference by taking into consideration the interference affecting neighboring cells in addition to the interference given by a path loss within the cell in the service area and neighboring cells. Non-patent document 4 has introduced a method, in which an amount of interference given by neighboring cells is measured for each cell and when the amount of interference given exceeds a fixed threshold value, a report is made using an indicator of charging or individual mobile stations are notified and a mobile station that has received the charging indicator reduces the transmit power in order to reduce interference. Non-patent document 1: 3GPP TR (Technical Report) 25,814, V1.5.0 (2006-5), Physical Layer Aspects for Evolved UTRA. http // www.3gpp.org / ftp / Specs / html-info / 25814.htm Non-patent document 2: Nokia, Uplink inter cell interference mitigation and text proposal, 3GPP TSG RAN WG1 Meeting # 44, Denver, USA, 13 -17 February 2006, R1-060298 Non-patent Document 3: Texas Instruments, Uplink Power Control for EUTRA: Optimizing the Trade-off between Cell-Edge and Cell-Average Throughputs, 3GPP TSG RAN WG1 Meeting # 47, Riga, Latvia , 6-10, November, 2006, R1-063231 Non-patent document 4: NTT DoCoMo, et al, Transmission Power Control in E-UTRA Uplink, 3GPP TSG RAN WG1 Meeting # 47, Riga, Latvia, 6-10, November, 2006, R1-063316TBD
Additional prior art is known from EP 1 434 455, where resource units are allocated within a cell of a wireless time-division duplex communication system using multiple code-division accesses. Each of the resource units is associated with a time slot and a code. For those selected from the cell's resource units, the interference code level is measured during that unit time slot and using that unit code. The interference code level is compared to a threshold to determine if this unit has an acceptable code interference level. Resource units are allocated for communications outside the unit's acceptable interference levels.
Description of the Invention
ES 2 393 767 T3
Problem to be solved by the invention
However, as the interference coordination method described above, in which the frequency band is divided, there is a problem that the effect of frequency diversity is reduced due to dividing the frequencies of the mobile station from the frequencies. that you can do use. Additionally, there is another problem that capacity deteriorates when there are a number of mobile stations of the same quality in a cell.
Additionally, as the method described above, in which the amount of interference between uplink cells is reduced by adjusting the transmit power, a problem arises in that the performance is reduced on the contrary in part of the bandwidth. frequency because the amount of interference between uplink cells is measured for each cell and even when using a frequency band currently with low interference, control is taken in such a way that the transmission power of the mobile stations in the entire cell is uniformly reduced indiscriminately.
Additionally, as for the method described above, in which the transmission power of the mobile station is reduced by using the load indicator, there is a problem that it is not possible to correctly reflect the amount of interference given at the current transmission time due to that the amount of interference varies considerably depending on the presence of a mobile burst transmitting station. In order to reflect the amount more correctly, it is required to increase the update frequency of the load indicator, however, another problem will arise that the power consumption of the mobile station is increased due to the receiving frequency of the station mobile is increased at the same time.
The present invention has developed the aforementioned problems which are taken into consideration and an object thereof is to provide a mobile communication system according to claim 1, a base station apparatus according to claim 4, and a method of communication according to claim 5.
Additionally, the description presents an example of a mobile communication system comprising a mobile station apparatus and a base station apparatus, wherein the base station apparatus divides an uplink channel frequency band into a predetermined number of bands and creates an interference information indicator table showing the relative magnitude of interference in each frequency band based on the quality of the signal. channel for each of the divided frequency bands and the mobile station apparatus performs a data transmission according to the transmission resource allocation based on the table Indicator of interference information created by the base station apparatus.
As described above, based on the interference information indicator table created in the base station apparatus, the mobile station apparatus performs a data transmission in accordance with the transmission resource allocation based on the information indicator table. interference created by the base station apparatus. Because of this, it is possible to perform programming of a low interference frequency band in the base station apparatus for allocation of the low interference frequency band in the mobile station apparatus, and therefore, the performance of the mobile station can be improved. complete system. Additionally, by selecting a frequency band with low interference, the transmission power when transmitting data can be suppressed, and therefore, it becomes possible to realize the reduction in power consumption. As a result, it becomes possible to improve the performance of the entire system while reducing power consumption.
Additionally, the description presents an example of a mobile communication system comprising a mobile station apparatus and a base station apparatus, wherein the base station apparatus comprises a cell edge determination step that determines whether or not the apparatus mobile station is located on one edge of the cell, an interference determining step for determining an interference state for each predetermined frequency band based on the channel quality of the determined mobile station apparatus to be located at a cell edge by the cell edge determining step, and a table creation step that creates an interference information indicator table based on the determination result for each frequency band by the interference determination step, and the mobile station apparatus performs a data transmission in accordance with the allocation of the transmission resource based on the interference information indicator table created by the base station apparatus.
As described above, based on the channel quality of the uplink channel of the mobile station apparatus it is determined that it is located on an edge of the cell, the interference state is determined for each frequency band, and the indicator table interference information is created according to the determination result, and therefore, It is possible to notify the mobile station apparatus of the magnitude of inter-cell interference only for each frequency band by making a measurement of a channel quality indicator and a simple determination of the threshold value. Then, in the mobile station apparatus, the reported state of inter-cell interference is determined and a frequency band with low interference is determined as a frequency band of a measurement pilot channel, and therefore, it is possible to receive the measurement pilot channel in
ES 2 393 767 T3 a frequency band with low interference and perform programming based on the base station apparatus, and therefore, the performance of the whole system can be improved.
In an example of a mobile communication system, the interference determination step corrects the channel quality for each predetermined frequency band using correction data created from a demodulation pilot channel and the table creation step that creates the flag table. of interference information based on the corrected channel quality for each predetermined frequency band.
As described above, the channel quality for each predetermined frequency band is corrected using the correction data created from the demodulation pilot channel and the interference information indicator table is created based on the corrected channel quality for each band. default frequency, and therefore it becomes possible to create an indicator table of interference information with greater precision by using a demodulation pilot channel with low interference.
In an example of a mobile communication system, the mobile station apparatus comprises, a mobile station apparatus side table creation step that creates an interference information indicator table on the mobile station apparatus side by calculating a recorded value for each predetermined frequency band in at least one of the indicator tables of interference information obtained from the base station apparatus in the service area or the base station apparatus in the non-service area, and a frequency band determining step determining an interference state for each uplink frequency band based on the mobile station apparatus side of the interference information indicator table and determining a frequency band for which a request is made for the allocation of the transmission resource.
As described above, the interference information indicator table on the mobile station apparatus side is created by calculating a value recorded in the interference information indicator table for each predetermined frequency band, the interference status of the radio band. Uplink frequency is determined based on the interference information indicator table on the mobile station apparatus side, and the request for the allocation of the transmission resource is made, and therefore, it becomes possible to accurately determine the interference state according to the predetermined frequency bandwidth in the mobile station apparatus and makes a request for the allocation of the transmission resource in a frequency band with low interference.
In an example of a mobile communication system, the side table creation step calculates a value recorded in the interference information indicator table without duplication for each frequency band of a measurement pilot channel of the mobile station apparatus.
As described above, the value recorded in the interference information indicator table is calculated without duplication for each frequency band of the measurement pilot channel of the mobile station apparatus, and therefore, it becomes possible to appropriately create the indicator table of interference. interference information even when, for example, it is not possible to freely set a measurement pilot channel frequency band in order to ensure orthogonality.
In an example of a mobile communication system the frequency band determination step determines a frequency band with a minimum value calculated on the mobile station apparatus side of the interference information indicator table as a frequency band of the channel measurement pilot.
As described above, a frequency band with a minimum value calculated in the interference formation indicator table on the mobile station apparatus side is determined as a frequency band of the measurement pilot channel, and therefore, it is possible receiving the measurement pilot channel in a frequency band with low interference and programming based thereon in the base station apparatus. As a result, the performance of the entire system can be improved. Additionally, it is possible to suppress the transmission power when transmitting data by selecting a frequency band with low interference, and therefore, it becomes possible to realize the reduction in power consumption.
In an example of a mobile communication system, the frequency band determining step determines a frequency band with a maximum value calculated on the mobile station apparatus side of the interference information indicator table as a frequency band of the measurement pilot channel.
As described above, a frequency band with a maximum value calculated in the interference information indicator table on the mobile station apparatus side is determined as a frequency band of the measurement pilot channel, and therefore, it is possible autonomously multiplexing mobile station apparatus located in different cells in different frequency bands and suppresses inter-cell interference.
ES 2 393 767 T3
In an example of a mobile communication system, the frequency band determination step determines a frequency band with a calculated maximum value, which is obtained by subtracting a value recorded in the interference information indicator table of the base station apparatus. in the non-service area, of a value recorded in the interference information indicator table of the base station apparatus in the service area, as a frequency band of the measurement pilot channel.
As described above, on the side of the interference information indicator table mobile station apparatus, a frequency band with a calculated maximum value, which is obtained by subtracting a value recorded in the interference information indicator table of the base station in the non-service area of a value recorded in the interference information indicator table of the base station apparatus in the service area, it is determined as a frequency band of the measurement pilot channel, and therefore, it is possible to divide for each cell a frequency band to be used in mobile stations located in different cells and suppress inter-cell interference.
In an example of a mobile communication system, the frequency band determination step determines a frequency band with a maximum value calculated in the base station apparatus in the service area and with a minimum value calculated in the station apparatus. based on the non-service area based on the side of the interference information indicator table mobile station apparatus as a frequency band of the measurement pilot channel.
As described above, based on the side of the interference information indicator table mobile station apparatus, a frequency band with a maximum value calculated in the base station apparatus in the service area and with a minimum value calculated in the base station apparatus in the non-service area is determined as a frequency band of the measurement pilot channel. Due to this, mobile station apparatus located in different cells are automatically multiplexed into different frequency bands and a frequency band with less influence of interference on cells (neighboring cells) in the non-service area can be selected from among these, and therefore, it becomes possible to further suppress inter-cell interference.
In an example of a mobile communication system, the mobile station apparatus transmits the measurement pilot channel according to a frequency hopping pattern and the frequency band determination step performs programming not to transmit the measurement pilot channel in a frequency band with a maximum value calculated in the base station apparatus in the non-service area between the uplink frequency bands based on the mobile station apparatus side of the information indicator table of interference.
As described above, based on the mobile station apparatus side of the interference information indicator table, no programming is performed to transmit the measurement pilot channel in a frequency band with a maximum value calculated in the station apparatus. base on the non-service area between the uplink frequency bands, and therefore the influence of interference is averaged by frequency hopping and at the same time, It only happens that a transmission resource is assigned to a frequency band strongly affected by inter-cell interference from cells (neighboring cells) in the non-service area and it becomes possible to reduce inter-cell interference.
In an example of a mobile communication system, the mobile station apparatus transmits the measurement pilot channel according to a frequency hopping pattern and the frequency band determining step performs programming to transmit the measurement pilot channel at a reduced transmit power in a frequency band with a maximum value calculated in the base station apparatus in the non-service area between the uplink frequency bands based on the mobile station apparatus side of the table interference information indicator.
As described above, based on the mobile station apparatus side of the interference information indicator table, the schedule to transmit the measurement pilot channel at a reduced transmit power is performed in a frequency band with a maximum value. calculated in the base station apparatus in the non-service area between the uplink frequency bands, and therefore, The interference influence is averaged by frequency hopping and at the same time, the transmission power in a frequency band is strongly affected by the inter-cell interference from cells (neighboring cells) in the non-service area is reduced and it becomes possible to reduce inter-cell interference.
In an example of a mobile communication system, the mobile station apparatus comprises a mobile station apparatus side table creation step that creates an indicator table of interference information on the mobile station apparatus side by calculating for each predetermined frequency band a value recorded in at least one of the interference information indicator tables obtained from the base station apparatus in the service area or the base station apparatus in the non-service area and a control stage
ES 2 393 767 T3 transmit power that performs transmission power control of an uplink channel based on the mobile station apparatus side of the interference information indicator table.
As described above, the mobile station apparatus side of the interference information indicator table is created by calculating for each predetermined frequency band a value recorded in the interference information indicator table and the transmission power control is performed. performed based on the interference information indicator table on the mobile station apparatus side, and therefore, It is possible to properly perform the control of the transmission power according to a predetermined frequency bandwidth in the mobile station apparatus, and it becomes possible to reduce the reception errors in the base station apparatus and obtain the reduction effect. in power consumption.
In an example of a mobile communication system, the transmission power stage control performs the transmission power control based on a first increase / decrease value when the amount of interference given to the base station apparatus in the service area is greater than a threshold value, a second increase / decrease value when the amount of interference given to the base station apparatus in the service area is less than the threshold value, a third increase / decrease value when the amount of interference given to the base station apparatus in the non-service area is greater than the threshold value, and a fourth increase / decrease value when the amount of interference given to the base station apparatus in the non-service area is less than the threshold value based on the mobile station apparatus side of the interference information indicator table.
Because the control of the transmission power is performed as described above, it is possible to reduce the reception errors in the base station apparatus due to an increase in the transmission power when performing a data transmission in a frequency band. often with a lot of interference in a cell in the service area, and therefore, the performance of the mobile station apparatus is improved. On the contrary, when a data transmission is carried out in a frequency band with low interference in a cell in the service area, an undesired increase in the transmission power is suppressed by reducing the transmission power and this leads to savings of power in the mobile station apparatus. Additionally, when a data transmission is made in a frequency band with a lot of interference in a peripheral cell (cell in the non-service area), the transmission power is reduced, and therefore, the amount of interference given is reduced. to the peripheral cell and the quality of the peripheral cell is improved. On the contrary, when a data transmission is performed in a frequency band with low interference in a peripheral cell (cell in the non-service area), even if the transmission power is increased, the amount of interference from the peripheral cell is originally small, and therefore it is ensured that an increase in interference does not affect the peripheral cell strongly and because the transmission power is increased by one cell in the service area, The reception errors in the base station apparatus are reduced and the performance of the mobile station apparatus is improved.
In an example of a mobile communication system, the transmit power stage control performs the transmit power control based on a first target quality increase / decrease value when the amount of interference given to the broadcasting apparatus base station in the service area is greater than a threshold value, a second target quality increase / decrease value when the amount of interference given to the base station apparatus in the service area is less than the threshold value, a third target quality increase / decrease value when the amount of interference given to the base station apparatus in the non-service area is greater than the threshold value, and a fourth target quality increase / decrease value when the amount of interference given to the base station apparatus in the non-service area is less than the threshold value based on the mobile station apparatus side of the indicator table of interference information.
Because the control of the transmission power is performed as described above, it is possible to obtain the same effect as that when the transmission power is increased / decreased according to the interference state in the base station apparatus etc. in the service area.
Additionally, the description presents an example of a base station apparatus that communicates with a mobile station apparatus, comprising a cell edge determination step that determines whether or not the mobile station apparatus is located on an edge of the cell. , an interference determining step to determine an interference state for each predetermined frequency band based on channel quality of an uplink channel from the determined mobile station apparatus to be located on a cell edge by the step of determination of cell border, a table creation step that creates an interference information indicator table based on the determination result for each frequency band by the interference determination step, and a transmission stage that transmits the interference information indicator table to the mobile station apparatus or other base station apparatus.
As described above, based on the channel quality of the uplink channel from the determined mobile station apparatus to be located on one edge of the cell, the interference state is determined for each frequency band, and the indicator table interference information is created in accordance with the
ES 2 393 767 T3 determination result, and therefore, it is possible to notify the mobile station apparatus of the magnitude of inter-cell interference for each frequency band only by making a measurement of a channel quality indicator and a simple determination of the threshold value. Then, in the mobile station apparatus, the reported state of the inter-cell interference is determined, and a frequency band with low interference is determined as a frequency band of a measurement pilot channel, and therefore, it is possible to receive the measurement pilot channel in a frequency band with low interference and perform programming based on this in the base station apparatus, and therefore, the performance of the whole system can be improved.
In an example of a base station apparatus, the interference determination step corrects the channel quality for each predetermined frequency band using correction data created from a demodulation pilot channel, and the table creation step creates the indicator table of interference information based on corrected channel quality for each predetermined frequency band.
As described above, the channel quality for each predetermined frequency band is corrected using the correction data created from the demodulation pilot channel and the interference information indicator table is created based on the corrected channel quality for each band. default frequency, and therefore it becomes possible to create an indicator table of interference information with greater precision by using a demodulation pilot channel with low interference.
Additionally, the description presents an example of a mobile station apparatus communicating with a base station apparatus comprising a cell edge determination step that determines whether or not the mobile station apparatus is located on an edge of the cell, an interference determining step to determine an interference state for each predetermined frequency band based on the channel quality of an uplink channel from the determined mobile station apparatus to be located on a cell edge by the step cell border determination, a table creation stage that creates an interference information indicator table based on the determination result for each frequency band by the interference determination stage, and a transmission stage that transmits the interference information indicator table to the mobile station apparatus or other base station apparatus, or a base station apparatus comprising these components, wherein the interference determination stage corrects the channel quality for each predetermined frequency band using correction data created from a demodulation pilot channel and the table creation stage creates the interference information indicator table based on the quality channel corrected for each predetermined frequency band, the mobile station apparatus comprises a mobile station apparatus side table creation step that creates an indicator table of interference information on the mobile station apparatus side by calculating for each predetermined frequency band a value recorded in at least one of the interference information indicator tables obtained from the base station apparatus in the service area or a plurality of base station apparatus in the area of no service, a frequency band determination step determining an interference status for each uplink frequency band based on the interference information indicator table on the mobile station apparatus side and determining a frequency band for the which a request is made for the allocation of the transmission resource, and a transmission resource request stage requesting the base station apparatus for the transmission resource of the determined frequency band.
As described above, the interference information indicator table on the mobile station apparatus side is created by calculating a value recorded in the interference information indicator table for each predetermined frequency band, the interference status of the radio band. Uplink frequency is determined based on the interference information indicator table on the mobile station apparatus side, and request is made for the allocation of the transmission resource, and therefore, it becomes possible to accurately determine the interference status according to the predetermined frequency bandwidth in the mobile station apparatus and make a request for the allocation of the transmission resource in a frequency band with low interference.
In an example of a mobile station apparatus, the mobile station side of the table creation step calculates a value recorded in the unduplicated interference information indicator table for each frequency band of the measurement pilot channel.
As described above, the value recorded in the interference information indicator table is calculated without duplication for each frequency band of the measurement pilot channel of the mobile station apparatus, and therefore, it becomes possible to appropriately create the indicator table of interference. interference information even when, for example, it is not possible to freely set a frequency band of the measurement pilot channel in order to ensure orthogonality.
In an example of a mobile station apparatus, the frequency band determining step determines a frequency band with a minimum value calculated on the mobile station apparatus side of the interference information indicator table as a frequency band of the measurement pilot channel.
ES 2 393 767 T3
As described above, a frequency band with a minimum value calculated in the interference formation indicator table on the mobile station apparatus side is determined as a frequency band of the measurement pilot channel, and therefore, it is possible receiving the measurement pilot channel in a frequency band with low interference and programming based thereon in the base station apparatus. As a result, the performance of the entire system can be improved. Additionally, it is possible to suppress the transmission power when transmitting data by selecting a frequency band with low interference, and therefore, it becomes possible to realize the reduction in power consumption.
In an example of a mobile station apparatus, the frequency band determining step determines a frequency band with a maximum value calculated on the mobile station apparatus side of the interference information indicator table as a frequency band of the measurement pilot channel.
As described above, a frequency band with a maximum value calculated in the interference information indicator table on the mobile station apparatus side is determined as a frequency band of the measurement pilot channel, and therefore, it is possible automatically multiplex mobile station apparatus located in different cells in different frequency bands and suppress inter-cell interference.
In an example of a mobile station apparatus, the frequency band determination step determines a frequency band with a calculated maximum value, which is obtained by subtracting a value recorded in the interference information indicator table of the mobile station apparatus. in the non-service area of a value recorded in the interference information indicator table of the mobile station apparatus in the service area, as a frequency band of the measurement pilot channel.
As described above, on the mobile station side of the interference information indicator table, a frequency band with a calculated maximum value, which is obtained by subtracting a value recorded in the interference information indicator table of the monitoring device. base station in the non-service area of a value recorded in the interference information indicator table of the base station apparatus in the service area, it is determined as a frequency band of the measurement pilot channel, and therefore, it becomes possible to divide for each cell a frequency band to be used in mobile stations located in different cells and suppress inter-cell interference.
In an example of a mobile station apparatus, the frequency band determination step determines a frequency band with a maximum value calculated in the base station apparatus in the service area and with a minimum value calculated in the station apparatus. based on the non-service area based on the mobile station apparatus side of the interference information indicator table as a frequency band of the measurement pilot channel.
As described above, based on the mobile station apparatus side of the interference information indicator table, a frequency band with a maximum value calculated in the base station apparatus in the service area and with a minimum value calculated in the base station apparatus in the non-service area is determined as a frequency band of the measurement pilot channel. Due to this, mobile station apparatus located in different cells are automatically multiplexed into different frequency bands and a frequency band with less interference influence on cells (neighboring cells) in the non-service area can be selected from these. , and therefore, it becomes possible to further suppress the inter-cell interference.
In one example, the mobile station apparatus transmits the measurement pilot channel according to a frequency hopping pattern and the frequency band determination step performs programming not to transmit the measurement pilot channel in a frequency band with a maximum value calculated in the base station apparatus in the non-service area between the uplink frequency bands based on the mobile station apparatus side of the information indicator table of interference.
As described above, based on the mobile station apparatus side of the interference information indicator table, scheduling not to transmit the measurement pilot channel is performed in a frequency band with a maximum value calculated in the monitoring apparatus. base station in the non-service area between the uplink frequency bands, and therefore the interference influence is averaged by frequency hopping and at the same time, nothing happens except that the transmission resource that is assigned to a frequency band is strongly affected by inter-cell interference from cells (neighboring cells) in the non-service area and it becomes possible to reduce inter-cell interference.
In one example, the mobile station apparatus transmits the measurement pilot channel according to a frequency hopping pattern and the frequency band determining step performs programming to transmit the measurement pilot channel at a reduced transmit power in a frequency band with a maximum value calculated in the base station apparatus in the non-service area between the uplink frequency bands based on the mobile station apparatus side of the table interference information indicator.
ES 2 393 767 T3
As described above, based on the mobile station apparatus side of the interference information indicator table, the schedule to transmit the measurement pilot channel at a reduced transmit power is performed in a frequency band with a maximum value. calculated in the base station apparatus in the non-service area between the uplink frequency bands, and therefore, The interference influence is averaged by frequency hopping and at the same time, the transmission power in a frequency band is reduced, it is strongly affected by the inter-cell interference from the cells (neighboring cells) in the non-service area and makes it possible to reduce inter-cell interference.
Additionally, the description presents an example of a mobile station apparatus communicating with a base station apparatus comprising a cell edge determining step that determines whether or not the mobile station apparatus is located at an edge of the cell, an interference determining step to determine an interference state for each predetermined frequency band based on the channel quality of an uplink channel from the determined mobile station apparatus to be located on a cell edge by the step cell border determination, a table creation stage that creates an interference information indicator table based on the determination result for each frequency band by the interference determination stage, and a transmission stage that transmits the interference information indicator table to the mobile station apparatus or other base station apparatus, or a base station apparatus comprising these components, wherein the interference determination stage corrects the channel quality for each predetermined frequency band using correction data created from a demodulation pilot channel and the table creation stage creates the interference information indicator table based on the quality channel corrected for each predetermined frequency band, the mobile station apparatus comprises a mobile station apparatus side table creation step that creates an indicator table of interference information on the mobile station apparatus side by calculating for each predetermined frequency band a value recorded in at least one of the interference information indicator tables obtained from the base station apparatus in the service area or the base station apparatus in the non-service area, and a transmit power control stage that performs control of the transmit power of an uplink channel based on the interference information indicator table on the side of the mobile station apparatus.
As described above, the mobile station apparatus side of the interference information indicator table is created by calculating for each predetermined frequency band a value recorded in the interference information indicator table and the transmission power control is performed. performed based on the interference information indicator table on the mobile station apparatus side, and therefore, It is possible to properly perform the control of the transmission power according to a predetermined frequency bandwidth in the mobile station apparatus, and it becomes possible to reduce the reception errors in the base station apparatus and obtain the reduction effect. in power consumption.
In an example of a mobile station apparatus, the transmit power stage control performs control of the transmit power based on a first increase / decrease value when the amount of interference given to the base station apparatus at the service area is greater than a threshold value, a second increase / decrease value when the amount of interference given to the base station apparatus in the service area is less than the threshold value, a third increase / decrease value when the amount of interference given to the base station apparatus in the non-service area is greater than the threshold value, and a fourth increase / decrease value when the amount of interference given to the base station apparatus in the non-service area is less than the threshold value based on the mobile station apparatus side of the interference information indicator table.
Because the control of the transmit power is performed as described above, it is possible to reduce the reception errors in the base station apparatus due to a rise in the transmit power when performing a data transmission in a band of often with a lot of interference in a cell in the service area, and therefore, the performance of the mobile station apparatus is improved. On the contrary, when a data transmission is performed in a frequency band with low interference in a cell in the service area, an undesired increase in the transmission power is suppressed by reducing the transmission power and this leads to savings of power in the mobile station apparatus. Additionally, when a data transmission is performed in a frequency band with a lot of interference in a peripheral cell (cell in the non-service area), the transmission power is reduced, and therefore, the amount of interference given is reduced. to the peripheral cell and the quality of the peripheral cell is improved. On the contrary, when a data transmission is performed in a frequency band with low interference in a peripheral cell (cell in the non-service area), even if the transmission power is increased, the amount of interference from the peripheral cell is originally small, and therefore it is ensured that an increase in interference does not affect the peripheral cell strongly and because the transmission power is increased by one cell in the service area, The reception errors in the base station apparatus are reduced and the performance of the mobile station apparatus is improved.
In an example of a mobile station apparatus, the transmit power stage control performs the transmit power control based on a first target quality increase / decrease value when the
ES 2 393 767 T3 amount of interference given to the base station apparatus in the service area is greater than a threshold value, a second target quality increase / decrease value when the amount of interference given to the base station apparatus in the service area is less than the threshold value, a third target quality increase / decrease value when the amount of interference given to the base station apparatus outside the area is greater than the threshold value, and a fourth target quality increase / decrease value when the amount of interference given to the base station apparatus in the non-service area is less than the threshold value based on the mobile station apparatus side of the indicator table of interference information.
Because the control of the transmission power is performed as described above, it is possible to obtain the same effect as when the transmission power is increased / decreased according to the interference state in the base station apparatus etc. in the service area.
Based on the interference information indicator table created in the base station apparatus, a data transmission is performed according to the allocation of the transmission resource based on the interference information indicator table acquired from the base station apparatus. in the mobile station apparatus. Because of this, in the mobile station apparatus, it is possible to perform programming of a frequency band with low interference in the base station apparatus by selecting a frequency band with low interference, and therefore, performance can be improved. of the complete system. Additionally, by selecting a frequency band with low interference, the transmission power when transmitting data can be suppressed, and therefore, it becomes possible to realize reduction in power consumption. As a result, it becomes possible to improve the performance of the entire system while reducing power consumption.
Brief Description of Drawings
Figure 1 is a diagram showing radio resources partitioned by frequency band and time region.
Figure 2 is a diagram showing an arrangement of short blocks and long blocks in an uplink strip.
Figure 3 is a diagram showing a channel mapping example of pilot channel measurement and demodulation pilot channel on an uplink common pilot channel.
Figure 4 is a diagram showing another channel mapping example of the measurement of pilot channels and demodulation pilot channels in an uplink common pilot channel.
Figure 5 is a diagram for explaining a relationship between the channel mapping of the measurement pilot channels and the demodulation pilot channels and the data channels in an uplink common pilot channel.
Figure 6 is a diagram for explaining a relationship between the transmission bandwidth of a mobile station and CQI calculated on a base station.
Figure 7 is a diagram showing a relationship between the target quality and the transmission power of the mobile station.
Figure 8 is a diagram showing an example of frequency hopping control.
Figure 9 is a block diagram showing an example of a configuration of a mobile station included in a mobile communication system according to a first example.
Figure 10 is a block diagram showing a configuration of a transmission part of a mobile station according to the first example.
FIG. 11 is a diagram for explaining a method of assigning the subcarrier in an IDFT part in a transmission part of a mobile station in the first example.
Figure 12 is a block diagram showing an example of a configuration of a base station included in a mobile communication system according to the first example.
Figure 13 is a diagram showing a threshold value of a relative quality Qr, i = (Qn, i / Qn, 0).
ES 2 393 767 T3
Figures 14A-14c are conceptual diagrams when a base station according to the first embodiment calculates a total of CQIs based on the measurement pilot channel of a mobile station on an edge of the cell.
Figure 15 is a diagram showing a relationship between total CQI and an interference judgment threshold value.
Figure 16 is a diagram showing an example of an interference information indicator table shown in Figure 15.
FIG. 17 is a diagram showing an example when the interference magnitude is determined by a plurality of interference determination threshold values.
FIG. 18 is a diagram showing an example of an interference information indicator table of a plurality of cells.
FIG. 19 is a diagram showing an example of a summed interference information indicator table according to each transmission bandwidth of various measurement pilot channels.
Figure 20 is a diagram showing another example of channel mapping of measurement pilot channels in which the transmit frequency band is restricted.
FIG. 21 is a diagram showing an example of a summed interference information indicator according to the transmission bandwidth of the measurement pilot channel in which the transmission frequency band is restricted.
Figure 22 is a diagram for explaining a relationship between the CQI value and the weighting factor when weighting is performed according to the quality of the downlink CQI.
Figure 23 is a diagram showing an example of an interference information indicator table when the predetermined weighting is performed for the interference information indicator table shown in Figure 18.
FIG. 24 is a diagram for explaining a relationship between the values recorded in an interference information indicator table and the transmission power increase / decrease stage widths.
Figure 25 is a diagram for explaining another relationship between the values recorded in an interference information indicator table and the transmission power increase / decrease stage widths.
Figure 26 is an example showing a relationship between the frequency bands from cell 1 to cell 3 and the values recorded in an indicator table of interference information in a mobile communication system according to a second example.
Figure 27 is a cell layout diagram corresponding to cell 1 to cell 3 in Figure 26.
Figure 28 is a diagram showing an example of an interference information indicator table created by subtracting a value recorded in an interference information indicator table of a peripheral cell from a value recorded in an interference information indicator table of a peripheral cell. cell in the service area in a mobile communication system according to a third example.
Figure 29 is a diagram showing an example of a summed interference information indicator table according to the transmission bandwidth of the measurement pilot channels in a cell in the service area and a peripheral cell in a system of mobile communication according to a fourth example.
Figure 30 is an example showing a relationship between the frequency bands from cell 1 to cell 3 and the values recorded in an indicator table of interference information in the mobile communication system according to the fourth example.
FIG. 31 is a diagram for explaining a relationship between values recorded in an interference information indicator table of a peripheral cell and an interference judgment threshold value in a mobile communication system according to a fifth example.
ES 2 393 767 T3
FIG. 32 is a diagram for explaining an example of frequency hopping control of the measurement pilot channels in the fifth example.
Figure 33 is a block diagram showing a configuration of a base station included in a mobile communication system according to a sixth example.
Explanations of Letters or Numerals
<td> 101</td><td>reception part</td>
<td> 102</td><td>channel demodulation part</td>
<td> 103</td><td>decoding part</td>
<td> 104</td><td>part of the control signal processing</td>
<td> 105</td><td>channel measurement part</td>
<td> 106</td><td>top layer</td>
<td> 107</td><td>interference data processing part</td>
<td> 108</td><td>programming part</td>
<td> 109</td><td>CQI calculation part</td>
<td> 110</td><td>coding part</td>
<td> 111</td><td>channel modulation part</td>
<td> 112</td><td>transmit power control part</td>
<td> 113</td><td>transmission part</td>
<td> 201</td><td>reception part</td>
<td> 202</td><td>channel demodulation part</td>
<td> 203</td><td>decoding part</td>
<td> 204</td><td>part of the control signal processing</td>
<td> 205</td><td>channel measurement part</td>
<td> 206</td><td>top layer</td>
<td> 207</td><td>CQI calculation part</td>
<td> 208</td><td>coding part</td>
<td> 209</td><td>programming part</td>
<td> 210</td><td>channel modulation part</td>
<td> 211</td><td>transmit power control part</td>
<td> 212</td><td>transmission part</td>
<td> 213</td><td>interference correction part</td>
Best Ways to Carry Out the Invention
ES 2 393 767 T3
Hereinafter, embodiments of the present invention and further examples are explained with reference to the drawings. Before explanation of embodiments of the present invention and further examples are given here, a basic technique and basic concept of a mobile communication system used in the present invention and additional examples are explained.
Figure 1 is a diagram showing an example of a radio frame configuration using OFDMA. A radio frame is used as a unitary region configured by a fixed frequency band in which a frequency axis is configured by a set of a plurality of subcarriers and a similarly fixed transmission time interval (subframe). A subframe is configured by a plurality of stripes and Figure 1 shows an example where two stripes are included in a subframe. A region partitioned by the fixed frequency band and the transmission time interval is called a resource block on a downlink and a resource unit on an uplink. BW in the figure denotes a bandwidth system and BR denotes a bandwidth of a resource block (or resource unit).
Figure 2 is a diagram showing an example of a symbol configuration in an uplink strip. An uplink strip is configured by eight symbols, that is, six long blocks and two short blocks. The short blocks are arranged in the second symbol from the top and the second symbol from the last and the long blocks are arranged in the rest of the symbols.
Then a physical channel used in EUTRA and its function is briefly explained below. A physical channel is classified into a data channel and a control channel. Additionally, as a control channel, there is a synchronization channel, a broadcast channel, a random access channel, a downlink common pilot channel, an uplink common pilot channel, a physical downlink control channel, and a physical uplink control channel. The uplink common pilot channel is sometimes referred to as an uplink reference channel and similarly, the downlink common pilot channel is referred to as a downlink reference channel, however, the essential functions are the same. .
Synchronization channel is a channel transmitted from a base station in a signal pattern already known in order for a mobile station apparatus (hereinafter appropriately referred to as a mobile station) to establish radio synchronization with a base station apparatus. (hereinafter appropriately referred to as a base station) and a channel that the mobile station receives first in EUTRA. Only the base station uses the sync channel.
The broadcast channel is a channel for broadcast information commonly used by mobile stations located in an area not only by a specific mobile station. It is possible for a mobile station to acquire information about a peripheral cell etc. through the broadcasting channel. Only the base station uses the broadcast channel.
The random access channel is an uplink channel on a contention basis used for uplink transmission when a mobile station is not notified of a radio resource that can be used by the mobile station from the base station. Only the mobile station uses the random access channel.
The downlink common pilot channel (hereinafter referred to as DL-CPICH) is a channel transmitted from a base station to a mobile station. The mobile station determines the received downlink quality by measuring the received DL-CPICH power. The received quality is uploaded to the base station using a physical uplink control channel as an indicator of channel quality (hereinafter referred to as a CQI). The base station performs downlink programming based on the CQI load.
As the received quality, the SIR (Interference to Signal Ratio), SINR (Noise Ratio plus Signal Interference), SNR (Noise to Signal Ratio), CIR (Interference to Carrier Ratio), BLER (Error Index of Block), or the loss of route can be conceived.
The uplink common pilot channel (hereinafter referred to as UL-CPICH) is a channel transmitted from a mobile station to a base station. The base station determines the received quality of an uplink transmitted signal from the mobile station by measuring the received UL-CPICH power. The base station performs uplink scheduling based on received quality. The UL-CPICH calculates the amounts of variation, such as amplitude, phase, and frequency, of an uplink data channel and is used as a reference channel to demodulate a data channel. Hereinafter, the UL-CPICH used for received quality determination is referred to as a measurement pilot channel and the UL-CPICH used for data channel demodulation is referred to as a distinction demodulation pilot channel.
The physical downlink control channel (PDCCH) is a channel transmitted from a base station to a mobile station and is commonly used by a plurality of mobile stations. Base station
ES 2 393 767 T3 uses the physical downlink control channel for transmission of the transmission time information and scheduling information (uplink / downlink resource allocation information).
The physical uplink control channel (PUCCH) is a channel transmitted from a mobile station to a base station and the mobile station uses the physical downlink control channel that the base station notifies of information, such as the Quality Indicator. Channel CQI, HARQ Hybrid Automatic Repeat Request, and ACK / NACK Acknowledgment / Not Acknowledgment (Acknowledge / Not Acknowledge).
Figure 3 shows an example of an uplink channel arrangement in EUTRA. The unit of frequency is expressed by Hertz (Hz) according to the International System of Units, however, there is no problem about a system in which the frequency is expressed by the number of resource blocks or resource units, or the number of subcarriers. BW in the figure denotes a bandwidth system. The demodulation pilot channel and the measurement pilot channel in the same mobile station are frequency division multiplexed into different frequency bands with the same time symbol and arranged in the distributed scheme (to be described later). Measurement pilot channels between different mobile stations are code division multiplexed in the same frequency band with the same time symbol and a plurality of mobile stations commonly use the same resource. The demodulation pilot channel is assigned only to a mobile station that has been programmed to transmit user data. The physical uplink control channels are arranged on both sides of the system bandwidth. In the rest, the data channels are arranged.
Figure 4 shows another example of an uplink channel arrangement in EUTRA. BW in the figure denotes a bandwidth system. The measurement of the pilot channels between the mobile stations with different transmission bandwidths of the measurement pilot channel are multiplexed by frequency division into different frequency bands with the same time symbol and arranged in the distributed scheme (which is will describe later), respectively. The measurement of the pilot channels in the mobile stations with the same transmission bandwidth of the measurement pilot channel are multiplexed by code division in the same frequency band with the same time symbol and a plurality of mobile stations commonly used the same resource. One difference from Figure 3 is that the measurement pilot channel and the demodulation pilot channel (not shown) are time multiplexed in Figure 4 and administered in different time symbols, that is, they are not transmitted simultaneously in the same time symbol.
Figure 5 shows a relationship between the demodulation pilot channel and the data channel in the uplink channel arrangement in EUTRA. The radio resource of a data channel assigned to a certain mobile station is included in the transmission bandwidth of the measurement pilot channel that is transmitted by the mobile station. It is necessary for the demodulation pilot channel to relate to the data channel so that it has the same transmission bandwidth as that of the data channel.
In Figure 3, Figure 4, and Figure 5, the description is such that the measurement pilot channel is arranged in the first symbol of the subframe, however, according to the present invention, it can be arranged in any position symbol, it is not limited to the first symbol, and can be arranged in the long block or the short block.
The transmission bandwidth of the measurement pilot channel varies depending on the performance of a mobile station being transmitted and, for example, it is assumed that there are three types of transmission bandwidth: 10 MHz; 5 MHz; and 1.25 MHz. Here, for example, when the bandwidth of the BW system is 20 MHz and the transmission bandwidth of the mobile station is 10 MHz to the maximum, and if it is planned to divide BW into two 10 MHz bandwidths for transmission of the measurement pilot channel, the received quality of the measurement pilot channel at the base station will be better when the measurement pilot channel is transmitted in a frequency band with less inter-cell interference, and therefore, performance is increased as a result. This is explained using Figure 6.
Figure 6 is an example showing the uplink CQI measurement result for each frequency band (four divisions in this example). Here, when a mobile station is arranged in any position of the frequency bands F1 to F3, if the mobile station transmits the measurement pilot channel at F2 in the example in Figure 6, the base station will receive a good CQI, however If the mobile station transmits the measurement pilot channel on F1 or F3, the CQI deteriorates compared to that when F2 is used. The main factor of the deterioration of the measurement pilot channel, that is, the factor of a low CQI that is determined at the base station, is the distance attenuation and other deterioration factors include inter-cell interference given by neighboring cells. .
Figure 7 is a diagram showing an example of a basic power control method in EUTRA. Because it is necessary to guarantee the quality of an uplink data channel, a target quality when
ES 2 393 767 T3 reception timing is determined in advance on the base station side. The target quality is reported at the mobile station by means of a broadcast channel or physical downlink control channel. The mobile station transmits the uplink data channel at the transmit power that satisfies the target quality. At this time, the mobile station determines the transmit power by adding the amount of attenuation due to path losses and the amount of attenuation due to the amount of interference indicating inter-cell interference for the target quality.
In Figure 7, when the target quality is Target1, the current transmit power is a transmit power Tx1, which is obtained by adding path loss Ptl1 and an amount of interference Intf1 for Target1. From Figure 7, it can be seen that the target quality can be achieved with lower transmit power when the quality is improved (path loss is reduced) or the amount of interference is reduced (interference is suppressed). cell). It can also be seen that the transmit power can be controlled by increasing / decreasing the target quality. Power control may include a method where the inherent cell offset value is added to the transmit power, however this is omitted in this example.
Figure 8 is an example to explain frequency hopping. To a mobile station or base station, an uplink or downlink radio resource is assigned on different frequencies in a regular time interval (Hopping interval). By frequency hopping it is possible to obtain a frequency diversity effect due to the use of different frequency bands and an interference averaging effect. BW in Figure 8 denotes a system bandwidth and it is shown that resources in different frequency bands are allocated to mobile stations UE # 1 to UE # 3 for each Hopping interval. This frequency hopping pattern is referred to as a hopping pattern.
(First example)
Hereinafter, a mobile communication system according to a first example is explained. Figure 9 is a block diagram showing an example of a configuration of a mobile station included in the mobile communication system according to the first example. A received signal (signal received from a base station) is received in a reception part 101. The received signal is sent to a channel demodulation part 102 and demodulated based on the input of scheduling information from a scheduling part, to be described later, and classified into a data channel, control channel (physical downlink control channel), and downlink common pilot channel (DL-CPICH).
Each rated channel is broadcast as follows. The data channel is transmitted to a decoding part 103, the control channel to a control signal processing part 104, and the downlink common pilot channel to a measurement part of channel 105. The different channels those described above are transmitted to the respective channel control parts, however, they do not affect the present example and are omitted.
The decoding part 103 takes user data and transmits it to an upper layer 106. The control signal processing part 104 takes the control data and transmits it to the upper layer 106. When the taken control data includes interference information (interference information indicator table, its details will be described later), the control signal processing part 104 transmits the interference information to an interference data processing part. 107. The interference data processing part 107 performs interference amount addition / subtraction processing for each frequency band to update the state where interference information can be used and at the same time, determines the amount of link interference. upstream for each frequency band of the interference information, and transmits the determination result to the upper layer 106 as interference control data. The scheduling information included in the control channel is transmitted to a scheduling part 108. The channel measurement part 105 measures the received quality of the downlink common pilot channel and transmits it to the upper layer 106 as data from measurement and at the same time transmits the received quality to a CQI calculating part 109. The CQI calculating part 109 calculates a CQI of the received quality and transmits it to the upper layer 106 as a CQI value.
As a CQI calculation method in the CQI calculation part 109, there is a method in which a CQI is found every time from an instantaneous value of DL-CPICH or a method in which a CQI is found by averaging a certain period of the fixed reception time, and can be used. Additionally, there is a method in which a CQI is found for each DL-CPICH and a method in which a CQI is found by averaging across a certain receive band, and both are included here. Even if calculation methods other than those described above are used, the essence of the present example is not affected.
On the other hand, from the upper layer 106, the user data, the control data, and the pilot data are input to an encoding part 110 and encoded as the transmission data. Additionally, from upper layer 106, scheduling information is input to scheduling part 108. User data and control data that is encoded in encoding part 110 are input to modulation part of channel 111. The
ES 2 393 767 T3 modulation part of channel 111 performs modulation processing of the transmission data in an appropriate modulation scheme according to the programming information transmitted from the programming part 108. A transmission power control part 112 performs appropriate power control of each channel in accordance with the instruction of programming part 108. The data modulated in the channel modulation part 111 is input to a transmission part 113 and subjected to power control and then transmitted from the transmission power control part 112. Other components of the mobile station are not related with the present example and is therefore omitted. The operation of each block is fully controlled by the top layer 106. The upper layer 106 or the scheduling portion 108 constitutes a table creation stage mobile station side and a frequency band determination stage. Most suitable as the mobile station side of the table creation stage and the frequency band determination stage is the scheduling part 108. Additionally, the transmission part 13 constitutes a transmission resource request stage.
Figure 10 is a block diagram showing a configuration of the transmission part 113 shown in Figure 9. The transmission data input from the modulation part of channel 111 is transformed S / P into an S / P transform part 1131 and then a plurality of pieces of time axis data is transformed into the frequency data by a part DFT 1132 and the transformed data are arranged in an IDFT part input in a subcarrier allocation part 1133. At an IDFT point with no input, 0 is inserted. The data undergoes IDFT processing in an IDFT 1134 part and then transformed into time axis data again, a Guard Interval is inserted into a Guard Interval insert part. Protection 1135. Then, after undergoing P / S transformation to P / S transformation part 1136 and D / A transformation to D / A transformation part 1137 in order, the data is transmitted from RF part 1138.
Here, two methods have been proposed as data arrangement rules for entering the IDFT part 1134. One is a method named as a localized schema and the other is a method named as a distributed schema. A localized arrangement is a scheme in which the frequency data after DFT is successively mapped to the IDFT input as shown in Figure 11 (a). On the other hand, a distributed layout is a scheme in which the same data is allocated at regulatory intervals for the IDFT input. It is possible for a mobile station to use a transmission format by switching between the localized arrangement and the distributed arrangement according to the type of channel, purpose, radio propagation environment, etc.
Figure 12 is a block diagram showing an example of a configuration of a base station included in the mobile communication system according to the first example. A received signal (signal received from a mobile station) is received in a reception part 201. The received signal is sent to a channel demodulation portion 202 and classified into a data channel, control channel (physical uplink control channel), and uplink common pilot channel based on the scheduling information and then demodulated, respectively. Channels other than those described above are transmitted to the respective channel control parts, however, they do not affect the present example and are therefore omitted.
Each of the demodulated data is transmitted as follows. The data channel is transmitted to a decoding part 203, the control channel to a control signal processing part 204, and the uplink common pilot channel (UL-CPICH) to a channel measurement part. 205. The decoding part 203 performs the decoding processing of the user data and transmits it to an upper layer 206. The control signal processing part 204 takes the control data and transmits it to the upper layer 206. The control data relates to the control of the channel demodulation part 202, the decoding part 203, and the programming is transmitted to each block. The channel measurement part 205 measures the received quality when the uplink common pilot channel is a measurement pilot channel and transmits it to the upper layer 206 as measurement data and at the same time, transmits the received quality to a part. calculation cQi 207. On the other hand, when the uplink common pilot channel is a demodulation pilot channel, the measurement portion of channel 205 calculates the reference data (amplitude, phase, amounts of frequency variation, etc., of the data channel uplink) for channel demodulation and transmits them to the channel demodulation part 202. The CQI computing part 207 calculates a CQI of the received quality and transmits it to the upper layer 206 as a CQI value.
On the other hand, triggered by a transmission request from the upper layer 206, the user data and the control data are input to an encoding part 208. Additionally, the scheduling information is input from the upper layer 206 to a part programming 209. User data and control data code in coding portion 208 are input to modulation portion of channel 210. The channel modulation part 210 performs modulation processing of the transmission data in an appropriate modulation scheme in accordance with the programming information transmitted from the programming part 209. A transmission power control part 211 performs appropriate control of the power of each channel according to an instruction of the programming part 209. The data modulated in the channel modulation portion 210 is input to a transmit portion 212 and subjected to power control and then transmitted from the
ES 2 393 767 T3 transmit power control part 211. Other components of the base station are not related to the present example and are therefore omitted. The operation of each block is fully controlled by the upper layer 206. The channel measurement part 205 and the upper layer 206 or the CQI calculation part 207 constitutes a cell edge determination stage and an interference determination stage. . As the most appropriate, the cell border determination stage and the interference determination stage is the CQI calculation part 207. The upper layer 206 constitutes a table creation stage.
It is easy to imagine that what significantly affects the increase / decrease of inter-cell interference is a mobile station on one edge of the cell as opposed to a mobile station in the center of a cell. Due to this, if it is possible to know a frequency band in which a mobile station on one edge of the cell transmits measurement of the pilot channels in a concentrated way, it becomes possible to average the interference affecting neighboring cells by avoiding the band of concentrated frequency. A method for this is shown below.
First, in order to determine whether a mobile station is in the center of a cell or on an edge of the cell, it is possible to determine at a base station using, for example, a downlink CQI reported from the mobile station or others. reported measurement values. During communication, it is also possible to use the quality received from a measurement pilot channel for determination. Various examples of the measurement method are shown below. In a method using downlink CQI, a certain forward CQI value is determined as a threshold value for each cell, and a mobile station reporting a CQI value better than the threshold value is determined to be located in the center of the cell. cell and that a mobile station reporting a CQI value is worse than the threshold value that is located on one edge of the cell. The CQI value that is equal to the threshold value is included in any other.
Additionally, as shown in Figure 13, there is another method, in which the relative quality Qr, i = (Qn, i / Qn, 0) obtained from the received quality Qn, 0 of a cell in the area of service and quality received Qn, i of the neighboring cells (i is the number of neighboring cells and i = 3, in the example) is compared with a threshold value and when all the Qr values are less than the threshold value, the cell is determined to be located in the center of the cell and when at least one of these is greater than the threshold value, the cell is determined to be located on an edge of the cell. When the received quality is measured, SIR, SINR, SNR, CIR, path loss, etc. are used. In this example, because Qr, 1 and Qr, 3 exceed the threshold value, it is determined that the mobile station is one located on an edge of the cell. If the threshold value to be used in the determination and the measured value to be used are broadcast or reported at the mobile stations individually, it is possible to perform any of the above-mentioned methods on the mobile station as opposed to the base station and for the mobile station notifying the base station of the result.
Then, in order to determine that the frequency band of the mobile stations on one edge of the cell is concentrated, it is possible to determine by calculating the total CQI of the uplink measurement pilot channel that that of the mobile station determined to be located on an edge of the transmitting cell and determines whether the total CQI is greater than a certain threshold value. When the total CQI is greater than a certain threshold value, it is determined that the mobile stations are arranged in order to focus on one and the same frequency band. This is because a difference in CQI between a mobile station located on one edge of the cell and another mobile station located on one edge of the cell in the same cell is comparatively small, and therefore, if the number of mobile stations using the same frequency band, the total CQI increases in value accordingly. This example is an example where a smaller CQI is assumed to mean better quality. Assuming that a larger CQI means better quality, it is necessary to sum the values calculated by subtracting a CQI from the maximum CQI. Hereafter, explanation is given on the assumption that a smaller CQI means better quality.
Figure 14A-14C shows conceptual diagrams of a total CQI calculation method. It is assumed that a mobile station UE1 and a mobile station UE2 are arranged on a cell edge in a certain cell. It is also assumed that a transmission bandwidth UE1_BW of the mobile station UE1 is divided into f1 to f4 and the transmission bandwidth UE2_BW of the mobile station UE2 is divided into f1 and f2. In this case, CQIUE1, 1 in Figure 14A is a CQI calculated at the base station using a measurement pilot channel from the mobile station UE1 at f1. Similarly, CQI UE2, 1 in Figure 14B is a CQI calculated at the base station using a measurement pilot channel from mobile station UE2 at f1. The same CQI calculation is performed on all mobile stations on one edge of the cell in the cell and the results are added to each frequency band divided across the bandwidth BW the system to obtain the total CQI in each band of frequency. In Figure 14C, the total CQI1 value of CQIue1, and CQIue2, 1 is the total CQI.
The base station creates a table (interference information indicator table) showing relative magnitudes of interference in a certain frequency band by comparing the total CQI for each frequency band calculated by the above-mentioned method and a given interference determination threshold in advance through the system bandwidth. Specifically, when the total CQI in a certain frequency band is greater than the interference determination threshold value, it is determined that the amount of
ES 2 393 767 T3 interference is higher in this region and the corresponding value in the interference information indicator table is set to 1. On the contrary, when it is lower, the value is set to 0. Here, each band is caused match the minimum transmission bandwidth of the measurement pilot channel.
Figure 15 is an example showing a relationship between the total CQI and the interference determination threshold value. Figure 16 is an example of the interference information indicator table in Figure 15. When the minimum transmission bandwidth is 1.25 MHz, the BW transmission bandwidth is divided into 16 regions each has a bandwidth 1.25 MHz, that is, f1 to f16, as shown in Figure 15. The total CQI in f1 is greater than the interference determination threshold value, and therefore 1 is set in the box of f1 in the interference information indicator table in Figure 16.
It may also be possible to prepare a plurality of interference determination threshold values, which are not limited to one. An example where a plurality of threshold values is used is shown in Figure 17. In Figure 17, three interference determination threshold values are prepared and there are four magnitude ratio patterns compared to the total CQI, and therefore, for example, one of the values 0 to 3 is set in the indicator table interference information.
If expressed by a general expression, the number of bits x for the minimum required transmission bandwidth when using interference determination threshold values n is expressed by the mathematical expression (1).
[Mathematical expression 1] x = [Log<sub>2</sub>(«+ L) 1
For example, when the system bandwidth is 20 MHz, the minimum transmission bandwidth of the measurement pilot channel is 1.25 MHz, and an interference determination threshold value is used, the number of bits required to create the Interference information indicator table is (20 / 1.25) X 1 = 16 bits.
The interference information indicator table is reported from the base station to the mobile stations on a cell edge individually by means of a physical downlink control channel or downlink data channel, either the entire cell is reported by means of a broadcast channel and a mobile station determined to be located on a cell edge from the downlink CQI or the transmission power is acquired from the broadcast channel.
Although a method for creating an interference information indicator table using CQI is explained here, this is not limited but can be used as measured received quality. Additionally, the received uplink signal strength can be used. When the received signal strength is used, a measurement is made in the resource block units or in the subcarrier units, an average value is found according to the minimum bandwidth of the measurement pilot channel, and an indicator table Interference information is created from comparison between the average value and a threshold value.
FIG. 18 is an example showing interference information indicator table of a plurality of cells received by a certain mobile station. Figure 18 shows a table that has been placed next to the indicator table of interference information received from cell 1 to cell 3 at the mobile station and it is assumed that the respective frequency bandwidths are divided into 16 frequency bands. (the minimum transmission bandwidth is assumed to be 1.25 MHz) and the amount of interference is expressed by one bit. The mobile station determines a frequency band in which the inter-cell interference appears to be at least the above-mentioned interference information indicator table and transmits the measurement pilot channel in the determined frequency band. In this case, it is possible for the base station to receive the measurement pilot channel in a frequency band with low interference, and therefore, it is possible to perform programming for the mobile station based on an excellent uplink CQI.
A method for determining a frequency band with least inter-cell interference from the plurality of interference information indicator tables mentioned above is shown below. Two methods are shown by which the mobile station receives an indicator table of interference information from a cell in the service area and neighboring cells. Even if the method is used, the present example is not affected. Neighbor cells mean a group of cells with quality equal to or greater than a certain level and as information by which the mobile station determines quality equal to or greater than a certain level, for example, a downlink CQI is used, path loss , SINR, etc. Additionally, you can define the maximum number of cells to be used as a peripheral cell. The maximum number of cells can be common to the system or it can be
ES 2 393 767 T3 determine for each base station of the peripheral environment that is taken into consideration and then notify the mobile station.
The first method by which the mobile station receives an interference information indicator table is a method in which the mobile station is notified directly from a cell in the service area and neighboring cells or the mobile station receives the indicator table of reported interference information respectively. The second method by which the mobile station receives an interference information indicator table is a method in which a base station in a cell in the service area reports or reports an interference information indicator table that includes information about the cell in the service area and neighboring cells.
The base station establishes cell-to-cell communication between the base stations at certain time intervals in order to acquire / update the peripheral cell information and maintain the interference information indicator table of the plurality of neighboring cells. Alternatively, it may also be possible for the base station to acquire / update the neighboring cell interference information indicator table by periodically reporting the neighboring cell interference information indicator table received by the mobile station to the base station. In the case of the above-mentioned method by reporting from the mobile station, if all the mobile stations notify the information base station, the workload is increased. Because of this, it is recommended to trigger only one mobile station that satisfies a certain criterion, for example, a CQI mobile station which is less than a certain threshold value, to make a report.
The mobile station creates a new table of the received interference information indicator table by adding values according to the transmission bandwidth of the measurement pilot channel for each mobile station. Figures 19 (a) through 19 (c) are tables that are created when the transmission bandwidths are 1.25 MHz, 5 MHz, and 10 MHz, respectively. The smallest value shown in this table means low interference that affects cells other than the cell in question. That is, in Figure 19 (a), it is determined that interference is at least at f 11 and f13 where the value is 0. Similarly, in Figure 19 (b), it is determined that the interference is by at least in f10 to f13 where the value is 2 and in Figure 19 (c), it is determined that the interference is at least in f8 to f15 and f9 to f16 where the value is 8. As described above, a new table (mobile station side interference information indicator table) is created according to the transmission bandwidth of the mobile station measurement pilot channel, and therefore, it becomes possible to accurately determine the interference state according to the frequency bandwidth of the measurement pilot channel and determines a frequency band with low interference as a frequency band of the measurement pilot channel.
In the case where a frequency band capable of transmitting the measurement pilot channel cannot be freely set in order to ensure orthogonality and the frequencies are aligned, when the transmission bandwidth is 5 MHz, the table shown in Figure 19 (d) is created and when the transmission bandwidth is 10 MHz, the table shown in Figure 19 (e) is created. That is, it is determined that, in Figure 19 (d), the interference is at least in f9 to f12 where the value is 4 and in Figure 19 (e), it is determined that the interference is at least in f9 to f16 where the value is 8. As described above, even when the configuration of a frequency band of the measurement pilot channel cannot be freely done in order to ensure orthogonality, the interference information indicator table is created by adding the values recorded in the same band. frequency without duplication, and therefore, it becomes possible to appropriately create an indicator table of interference information.
A method for creating a mobile station interference information indicator table when the frequency band of a measurement pilot channel to be transmitted by the mobile station is limited in advance, as shown in Figure 20, is described go ahead. In Figure 20, the transmission bandwidth of the mobile station measurement pilot channel on one edge of the cell is limited to 1.25 MHz and additionally, it is arranged in a 5 MHz band at both ends of the 20 MHz band. On the other hand, the transmission bandwidth of the mobile station measurement pilot channel in the center of the cell is limited to 5 MHz or 10 MHz. The measurement of the pilot channels in different transmission bandwidths are multiplexed in the distributed arrangement. This is for the purpose of limiting the transmission bandwidth of the mobile station measurement pilot channel on one edge of the cell because the wider the transmission bandwidth of the measurement pilot channel becomes, the more is required. transmit power, thus saving power while ensuring the quality of the measurement pilot channel.
The base station determines an appropriate transmission bandwidth of a measurement pilot channel using the measurement value reported (CQI, path loss, etc.) from the mobile station. During the communication period, it may also be possible to use the measurement pilot channel as materials for determination. The determined transmission bandwidth of the measurement pilot channel of the mobile station is reported to the mobile stations individually. The mobile station creates a new table by adding values according to the reported transmission bandwidth of the measurement pilot channel and the frequency band that can be used. An example is given using the interference information indicator table in Figure 19 (a). When the transmission bandwidth of the mobile station measurement pilot channel is reported to be 1.25 MHz, only
ES 2 393 767 T3 required for mobile station to calculate the 5 MHz range at both ends. That is, the interference information indicator table created in the mobile station is one as shown in Figure 21, and the interference is determined to be at least f13. In this case, the determination of whether or not the mobile station is on an edge of the cell can be made from the transmission bandwidth of the measurement pilot channel notified from the base station, and therefore, it is not necessary to do determining the side of the mobile station.
In the method described above, the mobile station uniformly adds the interference information indicator table received from a cell in the service area and a plurality of neighboring cells without distinction. However, at present, if a nearby base station (base station in the cell in the service area) and a distant base station (base station in a peripheral cell) are compared, the influence of interference by the distant base station is relatively smaller than that by the nearby base station when transmitting at the same power. Because of this, it is possible to determine the amount of interference more accurately by adding the interference information indicator tables after weighting them than by adding them uniformly.
Figure 22 is an example when weighting according to CQI quality is performed. The horizontal axis in Figure 22 represents the CQI value and the vertical axis represents a weighting factor W. In the figure, CQIs, CQI n1, CQI n2 denote the CQI value in a cell in the service area, a peripheral cell 1, and a peripheral cell 2, respectively. Additionally, W0, W1, W2 denote the weighting factors for CQIs, CQIn1, CQIn2, respectively.
The mobile station receives the interference information indicator table from the cell in the service area and neighboring cells and at the same time finds a weighting factor of the CQI value. Then, the mobile station creates a new table by multiplying the interference information indicator table in the corresponding cell by the obtained weighting factor. After this, the mobile station creates a table similar to that in Figures 19 (a) to 19 (e) for each transmission bandwidth of the measurement pilot channel.
Figure 23 shows an example of an interference information indicator table created by a mobile station with a 1.25 MHz transmission bandwidth of the measurement pilot channel when weighting is performed for the interference information indicator table shown in the Figure 18 assuming that cell 1 is a cell in the service area, cells 2 to 3 are the neighboring cells, and W0 = 1, W1 = 0.5, and W2 = 0.3.
Although it is possible for the mobile station to determine a low interference frequency band from the interference information indicator table created by the mobile station itself, it is not clear to the base station that the frequency band has low interference. Additionally, if the mobile station determines, of its own accord, a frequency band in which a pilot measurement channel is transmitted, problems arise in the load that are concentrated in a specific frequency, such that the programming is reached to complicate, etc. Because of this, it is necessary to notify the base station of a frequency band in which the mobile station wishes to transmit a measurement pilot channel, that is, a frequency band in which the mobile station has determined interference is smaller. Hereinafter, said notification method is shown according to each of the various cases.
First, a method is shown for notifying a frequency band by the random access procedure when the mobile station does not connect with the base station. It is here assumed that the transmission bandwidth of the mobile station measurement pilot channel is specified in advance by the base station or is known because it has already been defined. The mobile station selects at least one low-interference frequency band (with smaller value) from the received interference information indicator table and reports the positional information around the frequency band to the base station. The information to be reported is included in a random access channel or a physical uplink control channel and resources (frequency band, code spread, etc.) of the measurement pilot channel are allocated from the base station via a physical downlink control channel.
Then, a method is shown for making a notification for the purpose of changing one frequency band to another with low interference when the mobile station connects with the base station. The mobile station selects at least one frequency band with low interference (smaller value) than that currently assigned from the received interference information indicator table and notifies the base station of the positional information of the frequency band. The information that is reported is included in a random access channel or a physical uplink control channel and resources (frequency band, code expansion, etc.) of the measurement pilot channel are reassigned from the base station via a physical downlink control channel. At this time, it is also possible for the base station to change the frequency bandwidth of the measurement pilot channel of the mobile station within the performance range of the mobile station as well as reallocation resources. Regardless of the presence / absence of the connection between the mobile station and the base station, it is possible to reduce the probability of collision of a random access channel when using, over a
ES 2 393 767 T3 priority basis, a frequency band that has been determined to have low interference from the interference information indicator table when the random access channel is transmitted.
In both cases, when two or more of the same minimum values are included in the interference information indicator table, at least one is randomly selected from the plurality of frequency bands.
It is preferable to adopt a sufficiently long frequency with which the mobile station receives the interference information indicator table in order to avoid power consumption by frequent reception by the mobile station. However, it is possible for the base station to update with a short frequency in order to reflect the interference state immediately. For example, there is a method to update the interference information indicator table each time a CQI is reported. The methods by which the mobile station determines an update rate of an interference information indicator table may include a method by which the mobile station itself determines an update rate of the interference information indicator table based on the speed of movement, transmission power, CQI, intermittent reception intervals, etc., of its own accord, a method determined by the system, and a method in which an update rate is notified from the base station.
The methods described above are those in which the uplink performance is improved by selecting a frequency band with low interference to suppress the interference, however, there is no specific control for the transmission power of the uplink data channel. . It is possible, however, to obtain an effect to further suppress interference by determining the transmit power by taking into consideration each value of the interference information indicator table in addition to the target quality, path loss, and the amount of interference when the mobile station transmits the uplink data channel.
As already explained in Figure 7, in order for the mobile station to meet the target quality Target1, transmit power Tx1 is required which compensates for the path loss Ptll and the amount of interference Intf1. Here, the target quality Target1 and the amount of interference Intf1 are reported in advance in the cell or reported with the mobile stations individually. It is possible to find the path loss Ptl1 from a difference between the transmit power of the downlink common pilot channel of the base station and the receive power of the downlink common pilot channel currently received by the mobile station.
Here, the amount of interference Intf1 is the amount of interference given to the entire cell but not found for each frequency band. That is, the occurrence of a difference between the amount of interference Intf1 and the actual amount of interference on the allocated resources means that there is a very small or very large chance that Tx1 transmission power may be requested. The mobile station according to the present example performs transmission power control using the interference information indicator table in order to compensate for the amount of interference for each frequency band. A method of transmitting power control is shown below.
First, if the value in the interference information indicator table of a cell in the service area, which corresponds to a frequency band in which the transmission resources of the uplink data channel are included, is an indicator value Since there is a lot of interference given to neighboring cells (the interference is a lot), transmission is made after reducing the transmission power by means of a fixed stage AS1. In this case, the transmit power will be Tx1 - AS1. On the contrary, if the value in the table indicating interference information of the cell in the service area is less, it is an indicator value of the interference given to neighboring cells (the interference is less), transmission is made after increasing transmission power through a fixed stage AS2. In this case the transmission power will be Tx1 + AS2.
Then, if the value in the peripheral cell interference information indicator table, which corresponds to a frequency band in which transmission resources of the uplink data channel are included, is an indicator value that it is a lot of that interference, transmission is made after increasing the transmission power by a fixed stage AN1. In this case, the transmit power will be Tx1 + AN1. On the contrary, if the value in the peripheral cell interference information indicator table is less an indicator value of this interference, transmission is made after reducing the transmission power by a fixed stage AN2. In this case the transmission power will be Tx1 - AN2.
The effect that can be expected from the transmission power control mentioned above is as follows. First, in the case where the interference given to neighboring cells by the cell in the service area (i.e., the interference given to neighboring cells) is taken into consideration, when the data transmission is made in a band of Frequently with a lot of interference in the cell in the service area, the transmission power is reduced, and therefore, the interference given to the neighboring cells is reduced, and the quality of the neighboring cells is improved. On the contrary, when the data transmission is done in a frequency band with low interference
ES 2 393 767 T3 in the cell in the service area, even if the transmission is increased, it is guaranteed that an increase in interference does not affect neighboring cells strongly because the amount of interference given to neighboring cells is originally small, and therefore, the reception errors are reduced in the base station because the transmission power is increased in the cell in the service area and the performance of the mobile station is improved.
On the other hand, in the case where the interference given to the cell in the service area by neighboring cells (that is, the interference given to the cell in the service area) is taken into consideration, when the data transmission it is done in a frequency band with a lot of interference in the peripheral cell, the transmission power is increased, and therefore, Reception errors at the base station in the cell in the service area are reduced and the performance of the mobile station is improved. On the contrary, when the data transmission is done in a frequency band with low interference in the peripheral cell, an unwanted increase in the transmission power is suppressed by reducing the transmission power, which leads to power savings in the peripheral cell. mobile station.
The AS1, AS2, AN1, AN2 described above are assumed to be positive numbers that include zero, respectively, and the values reported in the cell, or they are reported at the mobile stations individually, or they are determined at the mobile station before it is done. the transmission of the uplink data channel.
The values that mean that the interference is high and the interference is less simply means that the interference is high when the value is 1 and the interference is less when the value is 0 in the case where the values of the information indicator table of interference are represented by one bit (0 or 1). When the values are represented by two or more bits, a certain forward threshold value is determined in order to make a distinction between high interference and minor interference. The threshold value for the distinction can be notified in advance from the base station or can be determined by the mobile station of its own accord.
Additionally, it is possible to obtain the same effect as that in the case described above by increasing / decreasing the target quality as opposed to increasing / decreasing the transmit power. When the target quality is Target1, the target quality in each case described above is Target1 - AQ1, Target1 + AQ2, Target1 + AQ3, and Target1 - AQ4, respectively. AQ1 to AQ4 are assumed to be positive numbers and the values reported in the cell are either reported for the mobile stations individually, or determined at the mobile station before the uplink data channel transmission is made.
Although the case is shown where the increase / decrease stage width in the transmit power and the increase / decrease stage width in the target quality are constant, it may also be possible to appropriately change the stage widths according to the values in the interference information indicator table. Examples are shown in Figure 24 and Figure 25, in which an increase / decrease stage width of the values is found in the interference information indicator table when the increase / decrease stage width is in proportion to the values in the interference information indicator table. The values in the interference information indicator table can be those before the weighting is performed or those after the weighting is performed.
Figure 24 is an example when the increase / decrease stage width is in proportion to the values in the interference information indicator table. The horizontal axis in Figure 24 represents the value in the interference information indicator table and the vertical axis represents the stage width. In this case, SPmax is the maximum stage width and SPmin is the minimum stage width and these are reported from the base station or determined at the mobile station. SP1, SP2, are stage widths when the values in the interference information indicator table are Vs, Vn, respectively. L1, L2 are straight lines that increase proportionally from SPmin to SPmax with a fixed slope, respectively.
Here, when the value in the interference information indicator table is calculated as Vs, the stage width in the cell in the service area is determined as SP1 from the intersection with the straight line L1. Similarly, when the value in the interference information indicator table is calculated as Vn, the stage width in the peripheral cell is determined as SP2 from the intersection with the straight line L2. In Figure 24, (number of cells X 2) proportional lines are prepared although they are omitted for simplification of explanation.
On the other hand, Figure 25 is a diagram when the stage width is quantized in a fixed range instead of the stage width being in proportion to the value in the interference information indicator table. The horizontal axis in Figure 25 represents the value in the interference information indicator table and the vertical axis represents the stage width. In this case, SPmax is the maximum stage width and SPmin is the minimum stage width and is reported from the base station or determined at the mobile station. SP3, SP<sub>4</sub> are the stage width when the values in the interference information indicator table are Vs, Vn, respectively. L3 and L4 are straight lines that increase from SPmin to SPmax, respectively, with the same stage width or different stage widths.
ES 2 393 767 T3
Here, when the value in the interference information indicator table is calculated as Vs, the stage width in the cell in the service area is determined as SP3 from the intersection with the straight line L3. Similarly, when the value in the interference information indicator table is calculated as Vn, the stage width in the peripheral cell is determined as SP4 from the intersection with the straight line L4. In Figure 25, (number of cells X 2) straight lines are prepared although they are omitted for simplification of explanation.
It is preferable to set the transmit power again after the change and the target quality after the change by taking into account the increase / decrease stage width in the cell in the service area and in the peripheral cell. As a method, it may be possible to simplify the sum or give priority to any of these when the result in the cell in the service area is opposite to that in the peripheral cell. For example, when the interference is high in the cell in the service area and the peripheral cell, if the received quality is given priority in the peripheral cell, the transmission power is reduced and if the received quality is given priority in the cell in the service area, the transmission power is increased. The method for reconfiguring can be specified for each base station or can be determined at the mobile station.
When two or more neighboring cells are included in the interference information indicator table, it may be possible for the mobile station to perform only power control when the results of all the upper cells that are neighbors are equal. For example, when the number of neighboring cells is three, the transmission power control is performed as follows. If all the results for the three cells indicate a lot of interference, the transmit power is reduced and if at least one of the results indicates low interference, the transmit power is not changed or the transmit power is increased. Although the control method to directly increase / decrease the transmit power of a mobile station such as transmit power control is described as above, it can be a method to control the transmit spectrum density (PSD) power of a mobile station.
As described above, with the mobile communication system according to the first example, a frequency band with lower interference is determined as a frequency band of a measurement pilot channel between the uplink frequency bands, and by Therefore, it is possible to receive the measurement pilot channel in a frequency band with low interference at the base station and perform programming based on this, and the performance of the entire system can be improved as a result. Additionally, in a mobile station, it is possible to suppress the transmission power when transmitting data by selecting a frequency band with low interference, and therefore, it becomes possible to realize reduction in power consumption. As a result, it becomes possible to improve the performance of the entire system while reducing power consumption.
Additionally, in the mobile communication system according to the first example, the sum of the channel indicator quality (CQI) of the measurement pilot channel of a mobile station located on one edge of the cell is found for each frequency band with a fixed width at the base station and at the same time, the interference status of each frequency band is determined by comparing the sum result and an interference determination threshold value, and an interference information indicator table is created in accordance with the determination result. Because of this, it is possible for the base station to notify the mobile station of the magnitude of inter-cell interference for each frequency band of the interference information indicator table only by making a CQI measurement and a simple threshold determination. As a result, no more complicated calculations are needed, and therefore, it becomes possible to realize reduction in complication and reduction in power consumption.
(Second example)
In the mobile communication system according to the first example, a mobile station selects a frequency band with less interference influence and suppresses the interference. However, in the mobile communication system according to the first example, the reference is only the quality of the measurement pilot channel of a mobile station on one edge of the cell, and therefore, if this occurs it is a band of frequency in which the number of mobile stations on one edge of the cell is small and the number of mobile stations in the center of the cell is greater, mobile stations tend to focus on the frequency band in question and there is a possibility that current programming may be complicated. Because of this, in a mobile communication system according to a second example, inter-cell interference is reduced by a method in which a mobile station of a bandwidth system is divided and used automatically.
Hereinafter, the mobile communication system according to the second example is explained. In the mobile communication system according to the second example, the configuration of a mobile station and the configuration of a base station are the same as those in the mobile communication system according to the first example. However, in the mobile communication system according to the second example, only the information of the cells in the service area of the interference information indicator table used in the first embodiment is used, and therefore the circuits and the processing series that relate to the neighboring cells interference information indicator table are skipped from the mobile station and the station
ES 2 393 767 T3 base. Additionally, the method for determining a mobile station on a cell edge and the method for creating an indicator table of interference information in the base station are the same as those in the mobile communication system according to the first example. The interference information indicator table is reported from the base station to the mobile stations individually by means of a physical downlink control channel or downlink data channel, o It is reported in the entire cell by means of a broadcast channel and a determined mobile station to be located on a cell edge of the downlink CQI o the transmit power acquires the interference information indicator table from the broadcast channel. broadcasting. The method for determining an updated frequency of the interference information indicator table is the same as that in the mobile communication system according to the first example.
A mobile station creates a new table of the indicator table of interference information received from a cell in the service area by adding a value according to the transmission bandwidth of the measurement pilot channel for each mobile station. The method for creating a new table is the same as that in the mobile communication system according to the first example, however, the weighting processing is not necessary. The mobile station then selects a frequency band with a maximum value, that is, a region that gives the most significant interference to neighboring cells. In this case, if two or more of the same maximum values are included in the interference information indicator table, at least one value is selected randomly from the plurality of frequency bands. This uses the fact that the uplink interference does not increase so much in quantity even if the mobile stations are concentrated in a certain frequency band because the orthogonality between the mobile stations is maintained in one cell in the service area. This is explained using Figure 26, Figure 27.
Figure 26 is an example showing a relationship between the frequency bands in cell 1 to cell 3 and the values in an indicator table of interference information in the mobile communication system according to the second example. The horizontal axis in Figure 26 represents the frequency and the vertical axis represents the sum value of the indicator table of interference information in a certain frequency band. BW denotes a bandwidth system and the regions Ra to Rc are divisions m of BW, and their bandwidth is BW / m. Figure 27 is a cell layout diagram corresponding to cell 1 to cell 3 in Figure 26. There may be a method in which a BWe frequency band is prepared for one edge of the cell and this is divided into my splits are assigned instead of a method that uses full system bandwidth. In this case, the bandwidth of each cell will be BWe / m.
It is assumed that the Ra region in cell 1 gives interference more significantly (region with the maximum value in the interference information indicator table), mobile stations located on one edge of the cell of cell 1 are concentrated in the Ra region . In this case, in cell 2 and cell 3, the amount of uplink interference from cell 1 in the Ra region increases and the received quality (CQI) of the measurement pilot channel deteriorates, and on the other hand the amount Uplink interference from cell 1 is reduced in the Rb and Rc regions and the received quality (CQI) of the measurement pilot channel is improved. Because of this, mobile stations in cell 2 and cell 3 are concentrated in the Rb or Rc region as a result.
Then, if the value of the region Rb is greater than that of Rc in cell 2, the mobile stations located on one edge of the cell in cell 2 are concentrated on Rb and the mobile stations located on one edge of the cell in cell 3 are concentrated in the Rc region as a result. In this way, mobile stations located on a cell edge in each cell 1 to cell 3 are automatically multiplexed and arranged at different frequencies, and therefore, it is possible to suppress inter-cell interference.
As described above, with the mobile communication system according to the second example, based on the new table created in the mobile station (interference information indicator table on the mobile station side), a band of frequency with the most interference as a measurement pilot channel frequency band between the uplink frequency bands, and therefore, It is possible to divide the frequency band used by mobile stations located in different cells for each cell and it becomes possible to suppress inter-cell interference.
It is also possible to combine the control of the transmission power displayed in the mobile communication system according to the first example with the mobile communication system according to the second example.
(Third example)
In the mobile communication system according to the second example, the mobile station divides the bandwidth of the system automatically and thus reduces inter-cell interference. However, in the mobile communication system according to the second example, the mobile station automatically determines that a frequency band is used, and therefore, it is not possible to completely separate the interference from a peripheral cell in a frequency band. , compared to the case where the base station divides the frequency forward, and you can
ES 2 393 767 T3 wait for the interference suppression effect to be reduced. That is, in the example in Figure 26, the mobile using the Rb or Rc region in cell 1 exists and there is a lot of interference from cell 2 and cell 3, respectively. Because of this, in a mobile communication system according to a third example, when the mobile station is automatically divided and uses the bandwidth of the system, not only a cell in the service area but also the cells are taken into consideration. neighbors.
Hereinafter, the mobile communication system according to the third example is explained. In the mobile communication system according to the third example, the configuration of a mobile station and the configuration of a base station may be the same as those in the first example.
In the third example, it may also be possible to use the interference information indicator table in Figure 28, which is obtained by subtracting the values in the neighboring cells (cell 2, cell 3 in the figure) from the values in the cell in the service area (cell 1 in the figure) in the interference information indicator table in Figure 18. Figure 28 shows an example when the transmission bandwidth of the mobile station measurement pilot channel is 1.25 MHz and the weighting factors W0 = 1, W1 = 0.5, W3 = 0.3 are multiplied in cell 1 to cell 3, respectively, however, it may also be possible to create a table without multiplying weighting factors W. Then, the mobile station selects a frequency band with a maximum value in the interference information indicator table in Figure 28, that is, a region of low interference from a peripheral cell. In this case, if two or more of the maximum values are included in the interference information indicator table, at least one is randomly selected from the plurality of frequency bands.
As described above, with the mobile communication system according to the third example, based on the new table created in the mobile station (interference information indicator table on the mobile station side), a band of frequency with the most interference as a measurement pilot channel frequency band between the uplink frequency bands, and therefore, It is possible to divide the frequency band used by mobile stations located in different cells for each cell and it becomes possible to suppress inter-cell interference.
It is also possible to combine the control of the transmission power shown in the mobile communication system according to the first example with the mobile communication system according to the third example.
(Fourth example)
In the mobile communication system according to the third example, the mobile station automatically divides the bandwidth of the system and reduces inter-cell interference. However, in the mobile communication system according to the third example, the interference given from a peripheral cell is calculated independently of the transmission bandwidth of the measurement pilot channel of the mobile station, and therefore cannot be achieve closure of interference control. Because of this, in a mobile communication system according to a fourth example, when a mobile station splits automatically and uses a bandwidth system, the interference given from a peripheral cell is taken into consideration for each of the bandwidths. transmission band of the mobile station measurement pilot channel.
Hereinafter, the mobile communication system according to the fourth example is described. In the mobile communication system according to the fourth example, the configuration of a mobile station and the configuration of a base station may be the same as that in the first example.
Figure 29 shows an example of an interference information indicator table used in the mobile communication system according to the fourth example. The method for creating an interference information indicator table is the same as that in the first example except that the cells in the service area and the neighboring cells are separated. Additionally, it is assumed that the method of determining a mobile station on a cell edge and the method of creating an indicator table of interference information of cells in the service area and neighboring cells are the same as those in the system. mobile communication according to the first example. The interference information indicator table is reported from the base station to the mobile stations individually by means of a physical downlink control channel or downlink data channel, or is reported for the entire cell by means of a downlink channel. broadcasting, and a mobile station determined to be located on a cell edge of the downlink CQI or the transmit power acquires the interference information indicator table from the broadcast channel. The method for determining an update frequency of the interference information indicator table may be the same as that in the mobile communication system according to the first example.
When the transmission bandwidth of the measurement pilot channel of the mobile station is Bq, the mobile station selects a frequency band with a maximum value between the sum of the values of the indicator table of interference information in the cells in the service area that corresponds to a frequency band Fm (Fm = Bq X p) with a bandwidth p times the transmission bandwidth Bq (p is a natural number that
ES 2 393 767 T3 satisfies p> 1 and the transmission bandwidth Fm after multiplying by p is equal to or less than the maximum transmission bandwidth of the mobile station). In this case, if two or more of the same maximum values are included in the interference information indicator table, at least one is randomly selected from the plurality of frequency bands. Additionally, a minimum value is selected from the values of the neighboring cells included in the range of the frequency band Fm. If two or more of the same minimum values are included in the range of the frequency band Fm, at least one is randomly selected from the plurality of frequency bands.
In the interference information indicator table shown in Figure 29, Bq = 1.25 MHz, p = 4 and at this time, Fm will be 5 MHz. Due to this, when looking for a region with a maximum value for the region of Fm = 5 MHz from the cell interference information indicator table in the service area, the result is the region at f13 to f16 and the region with a minimum value in the peripheral cell is the region at f13. From the above, the mobile station determines that a region in which the measurement pilot channel is transmitted is f13.
Figure 30 is an example showing a relationship between the frequency bands in cell 1 to cell 3 and the values in the interference information indicator table in the mobile communication system according to the fourth example. The horizontal axis in Figure 30 represents the frequency and the vertical axis represents the total value of the indicator table of interference information in a certain frequency band. Additionally, BW denotes a system bandwidth and the regions Ra to Rc are divisions m into which BW is divided and its bandwidth is BM / m. Ra1 and Ra2 are assumed to have the transmission bandwidth of the measurement pilot channel. You can do a method in which the BWe frequency band for one cell edge is prepared and divided into m divisions and assigned instead of a method in which the entire system bandwidth is used. At this time, the bandwidth of each cell will be BWe / m.
It is assumed that the region Ra in cell 1 is a region that gives interference more significantly (region that shows a maximum value in the table indicating interference information of the cell in the service area), mobile stations located on an edge from cell to cell 1 are concentrated in the Ra region. In this case, if a mobile station compares Ra1 and Ra2 and finds that the region Ra2 is a region that gives low interference from a peripheral cell (region that shows a minimum value of the sum of the indicator table of interference information in the cell peripheral), the mobile station determines which interference is least when the measurement pilot channel is transmitted in the Ra2 region. The same procedure is also performed in cell 2 and cell 3. In this way, mobile stations located on one edge of the cell in each cell 1 to cell 3 are automatically multiplexed and arranged at different frequencies and a frequency band with less interference influence on the peripheral cell is selected. from among these, and therefore, it becomes possible to further suppress inter-cell interference.
In the mobile communication system according to the fourth example, it is assumed that an arbitrary frequency band is selected from the frequency band Fm if the interference information indicator table is not received from the peripheral cell.
As described above, with the mobile communication system according to the fourth example, based on the new table created in the mobile station (interference information indicator table on the mobile station side), a frequency band with more interference in the cell in the service area and with less interference in the peripheral cell is determined as a frequency band of the measurement pilot channel between the uplink frequency bands. Due to this, mobile stations located in different cells are automatically multiplexed into different frequency bands and a frequency band with less significant interference influence on the peripheral cell is selected in the range of the transmission bandwidth of the measurement pilot channel. from among these, and therefore, it becomes possible to further suppress inter-cell interference.
It is also possible to combine the transmission power control shown in the mobile communication system according to the first example with the mobile communication system according to the fourth example.
(Fifth example)
Hereinafter, a mobile communication system according to a fifth example is described. The configuration of a mobile station and the configuration of a base station may be the same as that in the first example. However, in the mobile communication system according to the fifth example, only the neighboring cells information from the interference information indicator table used in the mobile communication system according to the first example is used, and thus Therefore, the processing circuits and series relating to the cell interference information indicator table in the service area are omitted from the mobile station and the base station. Additionally, it is assumed that the method for determining a mobile station on a cell edge and the method for creating an indicator table of interference information in the base station is the same as those in the mobile communication system according to the first example. . The information indicator table
ES 2 393 767 T3 interference is reported from the base station to the mobile stations individually by means of a physical downlink control channel or downlink data channels, o the entire cell is reported by means of a broadcast channel and a mobile station determined to be located on a cell edge from downlink CQI o the transmit power acquires the broadcast channel interference information indicator table . The method for determining an update frequency of the interference information indicator table may be the same as that in the mobile communication system according to the first example.
In the mobile communication system according to the fifth example, the base station transmits the frequency hopping pattern information (hereinafter referred to as FH information) of the measurement pilot channel to the mobile station together with the frequency allocation information. radio resources. The FH information received at the mobile station is transmitted to the scheduling part 108 as the scheduling information and is used as a transmission pattern when the measurement pilot channel is transmitted. The FH information may include a skip pattern from a channel other than the measurement pilot channel. The peripheral cell interference information indicator table and the FH information are reported from the base station to the mobile stations respectively by means of a physical downlink control channel or downlink data channel, or reported to the whole cell by means of a broadcast channel, and a mobile station determined to be located on a cell edge from the downlink CQI or the transmit power acquires the interference information indicator table from the broadcast channel.
Additionally, the mobile station creates a new table of the interference information indicator table received from the peripheral cell by adding a value according to the transmission bandwidth of the measurement pilot channel for each mobile station. The method for creating a new table is the same as that in the mobile communication system according to the first example, however, the weighting processing is not necessary. Then, the mobile station compares each value of the created table and a threshold value and determines a frequency band with a value greater than the threshold value. The threshold value is reported from the base station to the mobile stations individually by means of a physical downlink control channel or downlink data channel, or it is reported in the entire cell by means of a broadcast channel.
Figure 31 shows an example of a relationship between the above-mentioned threshold value and the new peripheral cell interference information indicator table. BW denotes a system bandwidth and is 20 MHz in Figure 31. Frequency bands f1 to f6 show the transmission bandwidth of the measurement pilot channel, which is 1.25 MHz in Figure 31. In this case, the mobile station compares each value from f11 to f16 and the threshold value mentioned above and stores the frequency bands with a value that exceeds the threshold value. In the example shown in Figure 31, f2, f15, and f16 are determined by exceeding the threshold value mentioned above.
Figure 32 is an example when the jump measurement pilot channel is transmitted using the FH information. BW shown in Figure 32 denotes a system bandwidth and Bq denotes the transmission bandwidth of the mobile station measurement pilot channel. Fm denotes a frequency band with a bandwidth p times Bq (p is a natural number that satisfies p> 1 and the transmission bandwidth Fm after multiplying by p is less than or equal to the transmission bandwidth maximum of the mobile station) and Fm = Bq X p.
The mobile station transmits the measurement pilot channel on different frequencies in regular time intervals (Hopping interval) according to the FH pattern included in the FH information. In this case, if the radio resource assigned according to the FH pattern is the same as that in the frequency band that exceeds the threshold value explained in Figure 31, the mobile station does not transmit the pilot channel for measuring the frequency band. but it mutates the frequency band.
Because it is not possible for the base station to measure a CQI (Channel Quality Indicator) of the mutated frequency band measurement pilot channel, the base station does not allocate a resource in the frequency band to the mutating mobile station. the broadcast. The mobile station transmits in accordance with the reported FH pattern until the peripheral cell interference information indicator table is updated.
As described above, with the mobile communication system according to the fifth example, different frequency bands are used by frequency hopping and on the other hand, a frequency band with more interference in the peripheral cell is determined from among the bands of uplink frequency, and programming is performed in such a way that the measurement pilot channel is not transmitted in the frequency band in question, and therefore, It becomes possible to reduce the inter-cell interference because the interference influence given to the peripheral cell is averaged by frequency hopping and at the same time, a resource is not allocated to the given frequency band significantly the inter-cell interference from the peripheral cell.
ES 2 393 767 T3
It may also be possible to perform transmission at reduced power as opposed to mutating the measurement pilot channel completely. At this time, the width to be reduced needs to be fixed or a fixed ratio to the original transmit power that needs to be used.
It is also possible to combine the transmit power control shown in the first example with the fifth example. For example, when a frequency band with more interference in the peripheral cell is determined and programming is performed in a reduced transmission power of the measurement pilot channel in the frequency band in question, it becomes possible to reduce the inter-cell interference due to because the interference influence is averaged by frequency hopping and at the same time, The transmission power of the frequency band is reduced significantly, the inter-cell interference from the peripheral cell is significantly reduced.
(Sixth example)
In a sixth example, a method is explained, which uses not only a measurement pilot channel but also a demodulation pilot channel in order to determine the amount of interference. Because the measurement pilot channel is transmitted in a state where a plurality of mobile stations are multiplexed in the same frequency band, there is a possibility that measurement errors may occur through inter-cell interference due to the collapse of the cell. orthogonality in the cell, however, the demodulation pilot channel band is occupied by a mobile station, and therefore, interference between mobile stations is less than the measurement pilot channel. An object of the present example is to correct the measurement errors using the demodulation pilot channel which has the characteristics previously described and creates an indicator table of interference information with greater precision.
Hereinafter, the mobile communication system according to the sixth example is described. Figure 33 is a block diagram showing an example of the configuration of a base station in the sixth example, the configuration of a mobile station may be the same as that in the first example. When the uplink common pilot channel is a demodulation pilot channel, the base station transmits reference data to the channel demodulation part 202 from the measurement part of channel 205 and furthermore, it transmits the reference data also to a interference correction part 213. The interference correction part 213 calculates the CQI value of the reference data and creates correction data to correct the measurement data and the CQI value for each mobile station, and transmits the data to the upper layer 206. The upper layer 206 corrects the measurement data and the CQI value of the mobile station based on the correction data. In the mobile station to which the demodulation pilot channel is not transmitted, the measurement data and the CQI value are calculated as usual only by the measurement pilot channel.
The base station creates an indicator table of interference information based on the corrected measurement data and the CQI value. The interference information indicator table is created according to the transmission bandwidth of the measurement pilot channel of the mobile station using the method of the examples described above. The created interference information indicator table is reported from the base station to the mobile stations individually by means of a physical downlink control channel or downlink data channel, or is reported to the entire cell by means of one channel. broadcasting, and a mobile station determined to be located on a cell edge of the downlink CQI or the transmit power acquires the interference information indicator table from the broadcast channel. The method for determining an update frequency of the interference information indicator table is the same as that in the mobile communication system according to the first example.
As described above, with the mobile communication system according to the sixth example, the measurement data and the CQI are corrected using the correction data created from the demodulation pilot channel, and the interference information indicator table is created. based on the corrected data, and therefore, It is possible to create an interference information indicator table with high precision, and because it becomes possible to predict interference with high precision, it becomes possible to further suppress inter-cell interference.
It is also possible to combine the transmission power control shown in the mobile communication system according to the first example with the mobile communication system according to the sixth example.
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Numbers
- Publication
- 2393767
- Application
- 8703937
Titles2
- Spanish
- Intercambio de una tabla de interfaz entre estaciones base
- English
- Exchange of an interface table between base stations
Classification
- CPC, 9
- H04W52/0206
- H04W72/541
- H04W52/12
- H04W52/146
- H04W52/243
- H04W52/362
- H04B17/345
- Y02D30/70
- H04W72/20
- IPC, 7
- H04B17 00
- H04W52 14
- H04W52 18
- H04W52 28
- H04W72 02
- H04W72 54
- H04W72 08