Method for controlling an uplink power in a wireless communication system and an apparatus in the system

The present invention relates to an uplink power control method in a wireless communication system and a host device in the system. The present invention is suitable, for example, for a radio communication system in which a radio base station that supports a specific radio channel and a radio base station that does not support a specific radio channel coexist.

In 3GPP (3rd Generation Partnership Project), HSUPA (High Speed) aims to speed up uplink (UL) packet communication in the direction from mobile stations (UE: User Equipment) to radio base stations (Node-B). Uplink Packet Access) is specified. HSUPA is also called EUL (Enhanced UpLink) to avoid confusion with HSDPA (High Speed Downlink Packet Access).

In EUL, the instantaneous transmission power of the UE tends to be high in order to improve the transmission rate of the uplink. Therefore, the interference power between adjacent cells in the cellular system tends to increase.

Therefore, between cells (Node-B) that support EUL, there may be some means at the network level to suppress the interference level of the UE located near the cell boundary.

For example, Patent Document 1 below discloses a base station that communicates with a mobile terminal existing in a subordinate cell and controls to reduce interference from a mobile terminal existing in an adjacent cell.

This base station measures the total interference power received from the mobile terminals of all adjacent cells, and if the total interference power is larger than the set value, requests the base stations of all adjacent cells to reduce the interference.

The base station that has received this interference reduction request determines a mobile terminal that may be interfering with the requesting base station, and temporarily lowers or uplinks the uplink data transmission rate of the mobile terminal. Interference is reduced by temporarily stopping data transmission.<patcit num="1"><text>International Publication No. WO 2006/087797 Pamphlet</text></patcit>

<p> However, in the above-mentioned prior art, the base stations (Node-B) forming adjacent cells support communication by EUL, and each base station can identify all the radio channels specified by EUL. It is assumed that the total interference power of UL for all adjacent cells can be measured at each adjacent base station.</p><p> That is, it is not assumed that an EUL-supported base station and an EUL-unsupported base station that does not support a part or all of the radio channels additionally specified by the EUL are mixed in the adjacent cell. Such a mixed configuration can occur during the transitional period between old and new systems.</p><p> Therefore, one of the objects of the present invention is to make it possible to appropriately suppress the interference of adjacent cells even in the mixed configuration as described above. Another object of the present invention is to improve the communication quality of the uplink by suppressing the interference of adjacent cells.</p><p> It should be noted that the present invention is not limited to the above-mentioned purpose, and it is an action and effect derived by each configuration shown in the best mode for carrying out the invention described later, and it is also possible to exert an action and effect which cannot be obtained by the conventional technique. It can be positioned as one of the purposes of.</p>

<p> In order to achieve the above object, the present specification discloses "uplink power control method in wireless communication system and higher-level device in the same system" shown below.</p><p> (1) That is, the uplink power control method in the wireless communication system disclosed herein is a second wireless terminal, a first wireless base station, and a second wireless channel that is not supported by the first wireless base station. An uplink power control method in a wireless communication system including a wireless base station and a higher-level device accommodating each of the above-mentioned wireless base stations.<u style="single">The information of the received power in the first radio base station is received from the first radio base station, and based on the information of the received power, the information of the received power is received.</u>The second radio base uses the radio channel that is not supported by the first radio base station when the interference power in the first radio base station is monitored and the monitoring result exceeds a predetermined threshold. Suppresses and controls the transmission power of the wireless terminal that communicates with the station.</p><p> (2) Here, the monitoring of the interference power is performed for each first cell in which the radio zone formed by the first radio base station is divided, and the radio terminal targeted for the suppression control is the first radio terminal. It may be a radio terminal that is a second cell that divides the radio zone formed by the two radio base stations and is located in a cell adjacent to the first cell whose monitoring result exceeds the threshold value. ..</p><p> (3) Further, the higher-level device holds information on the adjacency status of each cell formed by each of the radio base stations, and based on the information, the monitoring result is set to the first cell in which the monitoring result exceeds the threshold value. The second cell adjacent to the cell may be specified.</p><p> (4) Further, the monitoring of the interference power may be performed based on the received power information for each first cell reported from the first radio base station.</p><p> (5) Further, the suppression control limits the total transmission power of the uplink that can be allocated by the second radio base station to the radio terminal located in the second cell from the higher-level device. , The control may be such that the transmission power of the uplink assigned to the wireless terminal is reduced.</p><p> (6) Further, in the suppression control, a control signal common to or individual to the radio terminal located in the second cell is transmitted from the higher-level device to the second cell via the second radio base station. It may be carried out by transmitting.</p><p> (7) Further, the wireless terminal to which the individual control signal should be transmitted is a wireless terminal located in the second cell and located near the boundary with the first cell. May be.</p><p> (8) Further, the radio terminal located near the boundary is estimated by the higher-level device or the second radio base station based on the signal transmitted by the radio terminal located in the second cell. May be.</p><p> (9) Further, the higher-level device may generate information on the adjacent situation based on information on a wireless link formed between each wireless base station and the wireless terminal in the past.</p><p> (10) Further, the host device in the wireless communication system disclosed herein includes a wireless terminal, a first wireless base station, and a second wireless base station that supports a wireless channel that is not supported by the first wireless base station. And the higher-level device in the wireless communication system including the higher-level device accommodating each of the above-mentioned wireless base stations.<u style="single">The information of the received power in the first radio base station is received from the first radio base station, and based on the information of the received power, the information of the received power is received.</u>The interference power monitoring means for monitoring the interference power in the first radio base station, and the radio not supported by the first radio base station when the monitoring result by the interference power monitoring means exceeds a predetermined threshold. It is provided with a control means for suppressing and controlling the transmission power of a wireless terminal that communicates with the second wireless base station using a channel.</p><p> (11) Here, the interfering power monitoring means monitors the interfering power in units of the first cell in which the radio zone formed by the first radio base station is divided, and the control means said. As a wireless terminal to be suppressed, a second cell obtained by dividing a wireless zone formed by the second wireless base station and adjacent to a first cell whose monitoring result exceeds the threshold value. It may be possible to select a wireless terminal in the service area.</p><p> (12) Further, the higher-level device has a memory that holds information about the adjacency status of each cell formed by each of the radio base stations, and a second monitoring result that exceeds the threshold value based on the information in the memory. Specific means for identifying the second cell adjacent to one cell, and May be further provided.</p><p> (13) Further, the interference power monitoring means may monitor the interference power based on the received power information for each first cell reported from the first radio base station.</p><p> (14) Further, the control means limits the total transmission power of the uplink that can be allocated by the second radio base station to the radio terminal located in the second cell from the higher-level device. , The uplink transmission power allocated to the wireless terminal may be suppressed and controlled.</p><p> (15) Further, the control means transmits a control signal common to or individual to the wireless terminals located in the second cell to the second cell via the second radio base station. The suppression control may be carried out.</p><p> (16) Further, the control means is a wireless terminal located in the second cell as a wireless terminal to which the individual control signal should be transmitted, and is located near the boundary with the first cell. You may choose a terminal.</p><p> (17) Further, the control means may estimate the wireless terminal located near the boundary based on the signal transmitted by the wireless terminal located in the second cell.</p><p> (18) Further, the higher-level device generates information on the adjacent situation based on information on a wireless link formed between each wireless base station and the wireless terminal in the past, and stores the information in the memory. An adjacent cell information generation means may be further provided.</p>

<p> According to the above-disclosed technology, even when a radio base station (cell) that supports a specific radio channel and a radio base station (cell) that does not support a specific radio channel coexist, it is possible to appropriately suppress the interference of adjacent cells. It becomes.</p><p> It is also possible to improve the communication quality of the uplink by suppressing the interference of adjacent cells.</p>

<figref num="1">It is a figure which shows the structure of the wireless communication system which concerns on one Embodiment of this invention.</figref><figref num="2">It is a block diagram which shows the configuration example of the radio base station which does not support EUL shown in FIG.</figref><figref num="3">It is a block diagram which shows the configuration example of the EUL compatible radio base station shown in FIG.</figref><figref num="4">It is a block diagram which shows the configuration example of the wireless network control device (RNC) shown in FIG.</figref><figref num="5">It is a schematic diagram explaining the concept of the adjacent cell in the wireless communication system shown in FIG.</figref><figref num="6">It is a figure which shows an example of the data (adjacent cell information) in the inter-sector adjacency situation memory shown in FIG.</figref><figref num="7">It is a figure for demonstrating the automatic generation of data (adjacent cell information) in the inter-sector adjacency situation memory shown in FIG.</figref><figref num="8">It is a figure for demonstrating the automatic generation of data (adjacent cell information) in the inter-sector adjacency situation memory shown in FIG.</figref><figref num="9">It is a flowchart explaining the operation example of RNC shown in FIG.</figref><figref num="10">It is a schematic diagram explaining the EUL power control method in the wireless communication system shown in FIG.</figref><figref num="11">It is a schematic diagram explaining the 1st modification of the EUL power control method shown in FIG.</figref><figref num="12">It is a schematic diagram explaining the 2nd modification of the EUL power control method shown in FIG.</figref><figref num="13">It is a schematic diagram explaining the 3rd modification of the EUL power control method shown in FIG.</figref><figref num="14">It is a flowchart explaining the search process of the EUL power suppression target user in RNC of the 3rd modification.</figref>

Code description

10 Mobile station (user terminal: UE) 20A wireless base station (Node-B: EUL compatible base station) 21A receiving antenna 22A A / D converter 23A demodulator 24A decoder 25A interface (I / F) 26A encoder 27A modulator 28A D / A converter 29A transmit antenna 30A UL Scheduler 20B wireless base station (Node-B: base station that does not support EUL) 21B receiving antenna 22B receive front-end circuit 23B demodulator 24B decoder 25B interface (I / F) 26B encoder 27B modulator 28B amplifier 29B transmit antenna 40 Wireless Network Controller (RNC) 41 Interference power monitoring circuit 42 EUL power control circuit 43 Inter-sector adjacency memory 44 memory

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples, and there is no intention of excluding the application of various modifications and techniques not specified below. That is, the present invention can be implemented with various modifications (combining each embodiment, etc.) within a range that does not deviate from the gist thereof.

[1] Description of one embodiment FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment of the present invention. The system shown in FIG. 1 includes, for example, at least one mobile station (User Equipment (UE)) 10, at least one radio base station (Node-B) 20A that supports EUL, and EUL. It has at least one radio base station (Node-B) 20B that does not support it, and a radio network controller (RNC: Radio Network Controller) 40 that is positioned as a higher-level device that accommodates these radio base stations 20A and 20B.

In the following, the wireless base station 20A that supports EUL may be referred to as EUL compatible base station 20A, and the wireless base station 20B that does not support EUL may be referred to as EUL non-compatible base station 20B. It may be simply referred to as base station 20.

When UE10 is located in the wireless zone (wireless service area) formed by any of the wireless base stations 20A or 20B, it connects to the wireless base station 20A or 20B with a wireless link and connects to the other wireless base station 20A or 20B via RNC40. It is possible to communicate with communication devices such as server devices deployed in core networks (not shown) such as UE and the Internet.

The radio zone is divided into a plurality of cells such as 3 and 6, and radio resources such as a frequency, a time (transmission / reception timing), and a CDMA code to be used by the UE 10 can be assigned to each cell. The allocation is made according to the number of base stations and the physical arrangement of the base stations so that the limited radio resources can be used as effectively as possible while avoiding interference.

The radio link also includes an uplink (UL) channel in the direction from the UE 10 to the base station 20 and a downlink (DL) channel in the opposite direction. In EUL, in addition to the existing channels, a transport channel called E-DCH (Enhanced Dedicated Channel) is newly defined. For example, the physical channel of DL in EUL includes E-HICH, E-RGCH, E-AGCH and the like, and the physical channel of UL in EUL includes E-DPCCH, E-DPDCH and the like.

Here, E-HICH is an abbreviation for E-DCH (Enhanced Dedicated Channel) Hybrid ARQ (Automatic Repeat reQuest) Indicator Channel, and the EUL-compatible base station 20A notifies UE10 of the reception result (ACK / NACK) of UL data. It is a common channel used to do this.

E-RGCH is an abbreviation for E-DCH Relative Grant Channel, which is the current value of the transmission power (that is, transmission rate) that UE10 can use to transmit a data channel (for example, E-DPDCH) to EUL-compatible base station 20A. It is a common channel used for notifying by a relative value to (instructing the increase / decrease and maintenance of the transmission rate).

E-AGCH is an abbreviation for E-DCH Absolute Grant Channel, which is the absolute value of the maximum power (maximum transmission rate) that UE10 can use to transmit a data channel (for example, E-DPDCH) to an EUL-compatible base station 20A. It is a common channel used for notification.

E-DPDCH is an abbreviation for E-DCH Dedicated Physical Data Channel, which is an individual channel used by UE10 to transmit data to EUL-compatible base station 20A, and E-DPCCH is an abbreviation for E-DCH Dedicated Physical Control Channel. This is an individual channel used to transmit control information (transmission format, retransmission sequence number, etc.) related to E-DPDCH transmission from UE10 to EUL-compatible base station 20A.

The channel signals in these EULs are identified by the EUL-compatible base station 20A and subjected to modulation / demodulation processing, coding, and decoding processing, but are not identified by the EUL-non-compatible base station 20B, and the modulation / demodulation processing and coding are performed. No conversion or decoding process is performed. Therefore, even if the signal of the UL channel in EUL reaches the base station 20B that does not support EUL from UE10, it becomes a noise component (interference power) for the base station 20B.

In other words, the non-EUL base station 20B is positioned as the first radio base station that does not support the EUL radio channel, and the EUL compatible base station 20A supports the EUL radio channel that this base station 20B does not support. Positioned as the second radio base station. Then, the cell that divides the radio zone formed by the first radio base station 20B is positioned as the first cell, and the cell that divides the radio zone formed by the second radio base station 20A is positioned as the second cell.

FIG. 2 shows a configuration example of the EUL-compatible base station 20B, FIG. 3 shows a configuration example of the EUL-compatible base station 20A, and FIG. 4 shows a configuration example of the RNC 40.

(EUL non-compliant base station) As shown in FIG. 2, the EUL-incompatible base station 20B includes, for example, a receiving antenna 21B, a receiving front-end circuit 22B, a demodulator 23B, a decoder 24B, an interface (I / F) 25B, an encoder 26B, and a modulator. It is equipped with 27B, amplifier 28B and transmitting antenna 29B.

The receiving antenna 21B receives the UL radio signal transmitted by the UE 10, and the receiving front-end circuit 22B performs low noise amplification and frequency conversion to the baseband frequency for the signal received by the receiving antenna 21B. It has a function to perform reception processing such as down-conversion), A / D conversion, and band limitation by a filter.

The demodulator 23B has a function of demodulating the reception baseband signal obtained by the reception front-end circuit 22B by a demodulation method corresponding to the modulation method (QPSK, 16QAM, etc.) on the transmission side (UE10).

The decoder 24B decodes the signal demodulated by the demodulator 23B by a decoding method corresponding to the coding method on the transmitting side (UE10) (error correction decoding).

The interface 25B has an interface function with the RNC40 and transmits the decrypted data obtained by the decoder 24B to the RNC40, while the data (DL data) addressed to UE10 received from the RNC40 is sent to the encoder 26B. It is to be sent.

The encoder 26B encodes the DL data from the interface 25B by a predetermined coding method (error correction coding), and the modulator 27B is the encoding obtained by the encoder 26B. The data is modulated by a predetermined modulation method such as QPSK or 16QAM.

The amplifier 28B amplifies the modulated signal obtained by the modulator 27B to a predetermined transmission power, and the transmission antenna 29B transmits the signal after amplification by the amplifier 28B toward the radio service area. .. In FIG. 2, the D / A converter that converts the modulated signal into an analog signal and the frequency converter that frequency-converts (up-converts) the modulated signal to a radio frequency are not shown. Further, the receiving antenna 21B and the transmitting antenna 29B may be integrated for transmission / reception sharing.

In the EUL-incompatible base station 20B configured as described above, when the UL signal is received by the receiving antenna 21B, the demodulator 23B, after the predetermined reception processing is performed by the receiving front-end circuit 22B, It is demodulated and decoded by the decoder 24B and transmitted to the RNC40 via the interface 25B.

On the other hand, when the DL data from RNC40 to UE10 is received by the interface 25B, the data is encoded and modulated by the encoder 26B and the modulator 27B, and then the predetermined transmission power is transmitted by the amplifier 28B. It is amplified to and transmitted from the transmitting antenna 29B toward UE10.

(EUL compatible base station) On the other hand, as shown in FIG. 3, the EUL-compatible base station 20A has, for example, a receiving antenna 21A, an A / D converter 22A, a demodulator 23A, a decoder 24A, an interface (I / F) 25A, and coding. It is equipped with a device 26A, a modulator 27A, a D / A converter 28A, a transmitting antenna 29A, and a UL scheduler 30A.

Here, the receiving antenna 21A receives the UL radio signal transmitted by the UE 10, and the A / D converter 22A converts the received signal into a digital signal. However, in FIG. 3, the illustration of a low noise amplifier that amplifies the received radio signal with low noise and a frequency converter that frequency-converts (down-converts) the received radio signal to the baseband frequency is omitted.

The demodulator 23A demodulates the received baseband signal (digital signal) obtained by the A / D converter 22A according to the UL scheduling result (EUL scheduling information) by the UL scheduler 30A.

The decoder 24A decodes the demodulated signal obtained by the demodulator 23A according to the EUL scheduling information given by the UL scheduler 30A (error correction decoding).

The interface 25A has an interface function with the RNC40, and transmits the decoded data obtained by the decoder 24A to the RNC40, while transmitting the data (DL data) addressed to UE10 received from the RNC40 to the encoder 26A. It is a thing. However, the interface 25A of this example has a function of detecting the EUL power suppression request signal from the RNC40, and the EUL power suppression request signal can be transferred to the UL scheduler 30A.

The encoder 26A encodes the DL data from the interface 25A and the control information (including the EUL scheduling information) for UE10 generated by the UL scheduler 30A by a predetermined coding method (error correction coding). The modulator 27A modulates the encoded data obtained by the encoder 26A by a predetermined modulation method such as QPSK or 16QAM specified based on the EUL scheduling information.

The D / A converter 28A converts the digitally modulated signal obtained by the modulator 27A into an analog signal, and the transmitting antenna 29A converts the signal after D / A conversion by the D / A converter 28A into the analog signal. It is transmitted to the wireless service area. However, in FIG. 3, the illustration of a frequency converter that frequency-converts (up-converts) the modulated signal to a radio frequency, an amplifier that amplifies the modulated signal to a predetermined transmission power, and the like is omitted. Further, the receiving antenna 21A and the transmitting antenna 29A may be integrated for transmission / reception sharing.

The UL scheduler 30A executes UL scheduling (selection of UE10 to transmit Grant, transmission power (rate) allocation of selected UE10, etc.) in response to reception of a scheduling request transmitted by UE10. A known rule can be applied to the scheduling rule. Further, the scheduling result is given to the encoder 26A and the modulator 27A as described above in order to transmit to the UE 10 through a physical channel such as E-AGCH or E-RGCH.

Further, the UL scheduler 30A of this example reduces the transmission power to the UE 10 located in the cell of the own station 20A according to the information when the EUL power suppression request signal is detected by the interface 25A. Schedule to let. This makes it possible to suppress the interference power caused by EUL to the base station 20B that does not support EUL.

As will be described later, the UE 10 subject to transmission power suppression control is located in the cell of its own station 20A regardless of the distance from the cell end (distance from the base station 20B that does not support EUL) according to the control from the RNC 40. It may be all UE10s, or it may be a specific UE10 selected from UE10s located in the cell of the own station 20A, for example, near the cell end of the own station 20A (near the boundary with the cell of the base station 20B that does not support EUL). It may be UE10 which is estimated to give a large interference power to the base station 20B which does not support EUL like UE10 which is located. As an estimation method, for example, a method of measuring the pilot transmission power using UPH (UE power headroom) reported from UE10 and determining that UE10 having a higher measurement result is located near the cell edge can be considered.

In the EUL-compatible base station 20A configured as described above, when the UL signal is received by the receiving antenna 21A, it is converted into a digital signal by the A / D converter 22A, and then the demodulator according to the EUL scheduling information. It is demodulated and decoded by 23A and the decoder 24A, and transmitted to RNC40 via the interface 25A.

On the other hand, when the DL data from RNC40 to UE10 is received by the interface 25A, or when the EUL scheduling information is generated by the UL scheduler 30A, the data or information is the encoder 26A and the modulator 27A. After being encoded and modulated by the D / A converter 28A, it is converted into an analog signal and then transmitted from the transmitting interface 29A to UE10 located in the cell of the own station 20A.

The EUL scheduling information includes the result of scheduling the UL scheduler 30A to reduce the transmission power of the EUL channel as described above when the EUL power suppression request signal is detected on the interface 25A. , UE10 will be notified.

(RNC) Next, the RNC40 will be described. As shown in FIG. 4, the RNC 40 of this example includes, for example, an interference power monitoring circuit 41, an EUL power control circuit 42, an inter-sector adjacency status memory 43, and a memory 44.

Here, the interference power monitoring circuit (interference power monitoring means) 41 has a function of monitoring the interference power in the base station 20B that does not support EUL, and the interference power and a predetermined threshold value (interference power threshold value P1 or interference suppression release threshold value P2). To provide a function to compare (&lt;P1)), a function to control (manage) the operation mode (normal mode or interference suppression mode) according to the comparison result, and a guard period in which interference power is not monitored. It has a guard timer function.

The threshold value P1 or P2 is stored in, for example, the memory 44. Interference power monitoring can be performed, for example, based on the received power information periodically reported from the EUL-incompatible base station 20B. As this received power information, for example, "Received Total Wideband Power" specified in Chapter 5.2.1 of 3GPP TS 25.215 V7.2.0 (2007-05) can be used. Received Total Wideband Power indicates the total received power for each cell at the base station 20, and is reported from the base station 20 to the RNC 40 at regular intervals. The measurement function of "Received Total Wideband Power" is a function normally provided in existing base stations, and by using this for the interference power monitoring, the interference does not change the functional configuration of the existing base station. It is possible to realize power monitoring.

The EUL power control circuit 42, the inter-sectoral adjacency memory 43, and the memory 44 are not supported by the EUL-incompatible base station 20B when the interference power monitoring result by the interference power monitoring circuit 41 exceeds the predetermined interference power threshold P1. It functions as a control means for suppressing and controlling the transmission power of the UE 10 that communicates with the EUL-compatible base station 20A using the radio channel of. It should be noted that the suppression control also includes a control for stopping the transmission of UL of UE10.

Therefore, the inter-sector adjacency status memory 43 of this example stores information (adjacent cell information) regarding the adjacency status of the cells of the base station 20 under the RNC 40. The adjacent cell means a cell that transmits and receives the same carrier (frequency) to a certain cell and is physically adjacent to the cell.

For example, as shown schematically in FIG. 5, assuming that the radio zones of the two base stations 20A and 20B are each divided into 6 cells (# 1 to # 6), they are adjacent to cell # 1 of the base station 20A. The cells to be used are cells # 2 and # 6 of the base station 20A and cells # 4 of the base station 20B, and such an adjacency relationship is stored in the memory 43.

This adjacency relationship (adjacent cell information) can be represented as tree-structured data using an address pointer or the like, as shown in FIG. 6, for example. That is, in FIG. 6, cell # 1 of base station 20 of base station number # 1 is adjacent to cells # 5 and # 6 of base station 20 of base station number # 2, and base station number # 2 It is indicated by associating cell # 6 of base station 20 with an address pointer or the like that it is adjacent to cell # 1 of base station number # 1. Note that the adjacency of cells in the same base station 20 is not shown in FIG.

Adjacent cell information may be statically set and stored in advance at the time of system construction, etc., or dynamically set and stored based on the history information of wireless links formed in the past, and set in advance. It may be unnecessary. As one of the realization methods, for example, as shown in FIG. 7, when a handover request is received between a certain UE 10 and the base stations 20A and 20B under the RNC40, the RNC40 is shown by a dotted line in FIG. In addition, it is conceivable that cells # 2 and # 5 in which the handover has been performed are recorded in the memory 44 as adjacent cells.

That is, the RNC 40 generates the adjacent cell information based on the information of the radio link formed between each cell (base station 20) and the UE 10 in the past, and stores the adjacent cell in the inter-sector adjacency status memory 43. It may have a function as an information generation unit. This function may be implemented as one function of the EUL power control circuit 42, for example, or may be implemented in the RNC 40 as a function separate from the circuit 42.

Next, the EUL power control circuit 42 controls the EUL power in the cell (EUL compatible cell) of the EUL compatible base station 20A based on the interference power monitoring result in the interference power monitoring circuit 41.

For example, the EUL power control circuit 42 compares the interference power of a certain cell (non-EUL compatible cell) of the EUL-incompatible base station 20B monitored by the interference power monitoring circuit 41 with the thresholds P1 and P2. , When the interference power in the non-EUL compatible cell exceeds the interference power threshold P1, the EUL compatible cell adjacent to the non-EUL compatible cell is searched for in the intersectoral adjacency status memory 43, and the EUL compatible cell is used. Generates an EUL power suppression request signal and sends it to the target EUL-compatible base station 20A. Further, when the interference power in the EUL-incompatible cell is less than the interference power threshold value P2, an EUL power suppression release request signal is generated and transmitted to the target EUL-compatible base station 20A.

That is, the EUL power control circuit 42 of this example is a specific unit that identifies an EUL cell adjacent to an EUL-incompatible cell that exceeds the interference power threshold value P1 based on the adjacent cell information of the inter-sector adjacency status memory 43. It has the function of.

In the memory 44, the threshold values P1 and P2, the interference power monitoring result (interference power P3) at the time of transmitting the past EUL power suppression request signal, the other interference power monitoring circuit 41, and the EUL power suppression request issuing circuit 42 operate. It stores the necessary information in.

The past interfering power P3 is used for comparison with the current interfering power (P) monitored by the interfering power monitoring circuit 41 in the EUL power suppression request issuing circuit 42, and the guard is used according to the comparison result. The period is adjusted. For example, if P P3, it is judged that the interference suppression effect due to the issuance of the past EUL power suppression request signal has been obtained, and by setting a longer guard period than in the case of P&gt; P3, the following It is possible to control to delay the monitoring timing of the interference power. The memory 44 may be integrated with the inter-sector adjacency status memory 43 by dividing the storage area.

Hereinafter, the operation (EUL power suppression method) of the RNC40 and the wireless communication system configured as described above will be described with reference to FIGS. 9 to 14.

As shown in FIG. 9, the RNC40 uses the interference power monitoring circuit 41 to check whether or not the current state is within the guard period by the guard timer function (process 101), and if it is outside the guard period, each base station under the control station. The interference power (total received power per cell in base station 20) P reported periodically from 20 is compared with the interference power threshold P1 (from N route of process 101 to process 102).

As a result, if there is an EUL-incompatible cell in which the interference power P exceeds the interference power threshold P1 (P&gt; P1), the interference power monitoring circuit 41 checks whether the current operation mode is the interference suppression mode (processing). Processing from the Y route of 102 103) If it is not the interference suppression mode, the operation mode of the RNC40 is changed to the interference suppression mode, and the EUL power suppression request issuance instruction is given to the EUL power suppression request issuance circuit 42.

As a result, the EUL power suppression request issuing circuit 42 searches for an EUL-compatible cell adjacent to the EUL-incompatible cell that exceeds the interference power threshold value P1 from the inter-sector adjacency status memory 43, and EUL power suppression request signal for the EUL-compatible cell. Is generated and transmitted (process 104 from the N route of process 103). The EUL power suppression request signal may be transmitted once or redundantly multiple times within a certain period. The interference power P, which is the monitoring result at this time, is stored in the memory 44 as the interference power P3.

Here, as the EUL power suppression request signal, a control signal that suppresses the EUL throughput of the entire EUL-compatible cell can be used for the EUL-compatible base station 20A. In that case, it is possible to uniformly suppress the EUL power for UE10 in the EUL-compatible cell.

As an example of such a control signal (information element: IE), Maximum Target Received Total Wide Band Power and Reference Received Total Wide Band Power specified in 3GPP TS 25.433 V7.5.0 (2007-06) are available. Can be mentioned.

By this control signal, the total EUL power (total transmission power of UL) that can be used (allocated) by the EUL-compatible base station 20A in the EUL-compatible cell is suppressed (limited) from the RNC 40, which is schematically shown in FIG. As described above, the amount of power that can be allocated to UE10 tends to decrease uniformly due to EUL scheduling at the EUL-compatible base station 20A, and although the EUL throughput in the EUL-compatible cell may decrease, the interference power caused by the EUL. Can be expected to be suppressed with high accuracy.

Since it takes a certain amount of time for the EUL power suppression request signal to be received by the EUL-compatible base station 20A and the EUL power control to work (reflect), the interference power monitoring circuit 41 is preferably in the interference suppression mode. A certain guard period is set by the guard timer function after the state transition to is generated, and during that period, the interference power P is not monitored and the state transition is not performed (Y route of process 105 and process 101).

After that, when the guard period ends, the interference power monitoring circuit 41 starts monitoring the interference power P again (N route of process 101), and the interference power P exceeds the interference power threshold P1. It is checked whether or not the interference power of is still exceeding the interference power threshold P1 (process 102).

As a result, if it exceeds, the interference power monitoring circuit 41 checks whether or not the current mode is the interference suppression mode (from the Y route of the process 102 to the process 103). However, in this case, since the state has already transitioned to the interference suppression mode, the interference power monitoring circuit 41 compares the current interference power P with the past interference power P3 stored in the memory 44 (process 103). Processed from the Y route of 106).

As a result of this comparison, if the current interference power P exceeds the past interference power P3 (P&gt; P3: N route of processing 106), the interference power monitoring circuit 41 is the EUL power suppression request signal up to that point. Judging that the EUL power suppression effect by transmission is insufficient, the EUL power suppression request issuing circuit 42 is again instructed to issue an EUL power suppression request (process 104), and the EUL power suppression request issuing circuit 42 is EUL. A power suppression request signal is transmitted (process 105).

On the other hand, if the current interference power P is equal to or less than the past interference power P3 (P P3) (Y route of processing 106), the interference power monitoring circuit 41 uses the EUL by transmitting the EUL power suppression request signal up to that point. Judging that there was a power suppression effect, for example, a guard period (long cycle guard period) equal to or longer than the guard period in the process 105 is set, and during that period, the state transition is also performed without monitoring the interference power P. No (Y route of process 107, process 101).

By setting this long-period guard period, when the interference suppression mode continues for a certain period of time or longer, it can be judged that the interference power is not caused by EUL and the effect on suppressing EUL power is small, and it is erroneously determined. Can be reduced. However, the processes 106 and 107 can be omitted.

After that, when the guard period ends, the interference power monitoring circuit 41 starts monitoring the interference power P again (N route of process 101), and the interference power P for the cell that transmitted the EUL power suppression request signal is still present. It is checked whether or not the interference power threshold P1 is exceeded (process 102).

As a result, if the current interference power P is equal to or less than the interference power threshold P1 (P P1), the interference power monitoring circuit 41 further indicates whether the current interference power P is less than the interference suppression release threshold P2. Check whether or not (process 108 from the N route of process 102).

If the current interference power P is less than the interference suppression release threshold value P2 (P &lt;P2), the interference power monitoring circuit 41 transitions from the interference suppression mode to the normal mode, and the EUL power suppression request issuing circuit 42 is contacted. Generates and transmits an EUL power suppression release request signal for the target EUL-compatible cell (process 109 from the Y route of process 108). The release request signal may be transmitted once or redundantly a plurality of times within a certain period of time.

If the current interference power P is equal to or higher than the interference suppression release threshold value P2 (P P2), the interference power monitoring circuit 41 continues to maintain the previous mode (N route of process 108). If the normal mode continues for a certain period of time or longer, it is possible to determine that there is a margin in the radio resources and issue an EUL transmission power suppression release request to the target EUL-compatible cell. Further, although the process 108 realizes a so-called hysteresis process for the purpose of preventing frequent state transitions between the normal mode and the interference suppression mode, it can be omitted.

As described above, according to this example, in the EUL-incompatible cell formed by the EUL-incompatible base station 20B, the interference power received from the EUL-compatible cell formed by the EUL-compatible base station 20A due to EUL communication is correctly detected. Even if this is not possible, the RNC40, which is the host network device, can monitor the interference power of the cells that do not support EUL and suppress and control the EUL power of the cells that support EUL. Therefore, it is possible to suppress quality deterioration of existing services in cells that do not support EUL.

[2] First modification In the RNC40 (EUL power control circuit 42), in the interference suppression mode, as the above-mentioned EUL power suppression request signal, for example, as schematically shown in FIG. 11, UE10 located in the EUL-compatible cell sets the EUL-compatible base station 20A. It is also possible to use a control signal that can be commonly received via, for example, a Radio Resource Control (RRC) signal.

In this case, the EUL power of all UE10s in the EUL-compatible cell should be uniformly suppressed, including the UE10 that does not give interference power to adjacent EUL-compatible cells and does not require suppression of EUL power. Is possible. According to this method, the EUL power of the UE 10 can be directly suppressed without depending on the UL scheduling process in the EUL-compatible base station 20A.

[3] Second modification In the interference suppression mode, the RNC40 (EUL power control circuit 42) is a control signal (for example, RRC signal) individual to the UE 10 in the EUL-compatible cell as the above-mentioned EUL power suppression request signal, for example, as shown in FIG. ) Can be used to selectively suppress and control the EUL power of UE10 via the EUL-compatible base station 20A.

Here, as the UE 10 to be controlled by EUL power suppression, it is preferable to select the UE 10 located near the cell boundary that actually causes interference. In that case, RNC40 needs to estimate UE10, which is the source of interference. There are several methods for estimating the estimation. For example, a method for estimating the position of the UE 10 based on the RTT (Round Trip Time) reported from the base station 20 can be used. The method of mounting the estimation function on the RNC40 is free, but it may be provided to the EUL power control circuit 42, for example.

[4] Third modification The RNC40 (EUL power control circuit 42) notifies the EUL-compatible base station 20A of an EUL-compatible base station 20A, and the EUL-compatible base station 20A is the UE10 subject to UE power suppression, as shown schematically in FIG. Can be autonomously selected to individually suppress and control the EUL transmission power of the UE10.

In this case as well, it is preferable to select (estimate) UE10 located near the cell boundary that actually causes interference as the UE10 to be controlled by EUL power suppression. As the estimation method, for example, in addition to the method of estimating the position of the UE 10 based on the RTT (Round Trip Time), the UPH (UE power head room) reported from the UE 10 to the base station 20 is used to estimate the position of the UE 10. A method of measuring the pilot transmission power and estimating UE10 having a high pilot transmission power as UE10 located near the cell boundary can be considered.

When the latter method is adopted, in the EUL-compatible base station 20A, for example, the EUL scheduler 30A (see FIG. 3) operates according to the flow (processes 201 to 204) shown in FIG. 14, and the UE 10 reports the maximum UPH. Is searched for, and it is estimated (determined) that the UE10 is a UE10 subject to EUL power suppression located near the cell boundary.

That is, when the EUL scheduler 30A is started, first, as shown in FIG. 14, the parameters k, P_max, UE_maxInitialize (k = 0, P respectively)_max= 0, UE_max= -1) (Process 201). Where k is the UE number, P_maxIs maximum UPH (maximum pilot transmit power), UE_maxRepresents the UE number that reported the maximum UPH.

Then, the EUL scheduler 30A sets the maximum number of UEs in the EUL-compatible cell to N._maxAs a result, has the update process described below been completed for all UE10s in the EUL-compatible cell (k &lt;N)?_max(Process 202), and if not completed, the reported UPH (Pilot Transmission Power) P for UE10 with UE number k._kAnd maximum UPH (maximum pilot transmission power) P_maxCompare with (Process 202 from Process 202 Y Route 203).

As a result of the comparison, P_k&gt; P_maxIf so, the EUL scheduler 30A is P_max= P_k, UE_maxUpdate the maximum UPH and the UE number that reported the UPH with = k (from the Y route of process 203 to process 204). P_k P_maxIf, the EUL scheduler 30A does not make such an update (N route in process 203).

The EUL scheduler 30A completes the above processing for all UE10s in the EUL-compatible cell (k = N in processing 202)._maxRepeat until it is completed, and at that point, N_maxIn UE10 of the stand, P_maxIt is estimated (determined) that UE10 with UE number k that reported (maximum UPH) is UE10 located near the cell boundary and is an interference source.

Then, the EUL scheduler 30A schedules the UE 10 so as to reduce the EUL power, and transmits the scheduling result (EUL scheduling information) to the target UE 10 via a physical channel such as E-AGCH or E-RGCH. (See Figure 13). As a result, the EUL transmission power of UE10 is suppressed, and interference with cells that do not support EUL is suppressed.

[5] Others In the above-mentioned example, an example in which interference power monitoring and EUL power suppression are performed on a cell-by-cell basis has been described, but a unit in which a plurality of cells are grouped together, or one cell is further added to 3 sectors or 6 sectors. It may be carried out in sector units when it is divided into a plurality of sectors such as. Further, it is not impossible to carry out the operation for each radio zone formed by the base station regardless of the cell or sector configuration.<u style="single"> The following additional notes will be further disclosed with respect to each of the above embodiments.</u><u style="single"> [6] Appendix</u><u style="single"> (Appendix 1)</u><u style="single"> It includes a radio terminal, a first radio base station, a second radio base station that supports radio channels not supported by the first radio base station, and a host device that accommodates each of the radio base stations. It is an uplink power control method in wireless communication systems.</u><u style="single"> The higher-level device is</u><u style="single"> Monitor the interference power at the first radio base station and</u><u style="single"> When the monitoring result exceeds a predetermined threshold value, the transmission power of the radio terminal communicating with the second radio base station is suppressed and controlled by using the radio channel not supported by the first radio base station.</u><u style="single">An uplink power control method in a wireless communication system, characterized in that.</u><u style="single"> (Appendix 2)</u><u style="single"> The monitoring of the interference power is carried out in units of the first cell in which the radio zone formed by the first radio base station is divided.</u><u style="single"> The radio terminal targeted for the suppression control is a second cell in which the radio zone formed by the second radio base station is divided, and a cell adjacent to the first cell whose monitoring result exceeds the threshold value. It is a wireless terminal located in the area of</u><u style="single">The uplink power control method in the wireless communication system described in Appendix 1, which is characterized by the above.</u><u style="single"> (Appendix 3)</u><u style="single"> The higher-level device is</u><u style="single"> Holds information about the adjacency status of each cell formed by each radio base station.</u><u style="single"> Based on the information, the second cell adjacent to the first cell whose monitoring result exceeds the threshold value is specified.</u><u style="single">The uplink power control method in the wireless communication system described in Appendix 2, which is characterized by the above.</u><u style="single"> (Appendix 4)</u><u style="single"> The monitoring of the interference power is carried out based on the received power information for each first cell reported from the first radio base station.</u><u style="single">The uplink power control method in the wireless communication system according to Appendix 2 or 3, characterized in that.</u><u style="single"> (Appendix 5)</u><u style="single"> The suppression control limits the total transmission power of the uplink that can be allocated by the second radio base station to the radio terminal located in the second cell from the higher-level device, thereby limiting the total transmission power of the uplink to the radio terminal. A control that reduces the transmit power of the allocated uplink,</u><u style="single">The uplink power control method in the wireless communication system according to Appendix 2 or 3, characterized in that.</u><u style="single"> (Appendix 6)</u><u style="single"> The suppression control is performed by transmitting a control signal common to or individual to the wireless terminals located in the second cell from the higher-level device to the second cell via the second radio base station. Be done,</u><u style="single">The uplink power control method in the wireless communication system according to Appendix 2 or 3, characterized in that.</u><u style="single"> (Appendix 7)</u><u style="single"> The wireless terminal to which the individual control signal should be transmitted is a wireless terminal located in the second cell and located near the boundary with the first cell.</u><u style="single">The uplink power control method in the wireless communication system described in Appendix 6 is characterized in that.</u><u style="single"> (Appendix 8)</u><u style="single"> The radio terminal located near the boundary is estimated by the higher-level device or the second radio base station based on the signal transmitted by the radio terminal located in the second cell.</u><u style="single">The uplink power control method in the wireless communication system described in Appendix 7 is characterized in that.</u><u style="single"> (Appendix 9)</u><u style="single"> The higher-level device is</u><u style="single"> Information on the adjacency situation is generated based on the information of the radio link formed between each radio base station and the radio terminal in the past.</u><u style="single">The uplink power control method in the wireless communication system described in Appendix 3 is characterized in that.</u><u style="single"> (Appendix 10)</u><u style="single"> It includes a radio terminal, a first radio base station, a second radio base station that supports radio channels not supported by the first radio base station, and a host device that accommodates each of the radio base stations. The higher-level device in the wireless communication system</u><u style="single"> Interference power monitoring means for monitoring the interference power in the first radio base station, and</u><u style="single"> When the monitoring result by the interference power monitoring means exceeds a predetermined threshold value, the transmission power of the radio terminal that communicates with the second radio base station using the radio channel that is not supported by the first radio base station is transmitted. Control means to control suppression and</u><u style="single">A high-end device in a wireless communication system, which is characterized by having the above.</u><u style="single"> (Appendix 11)</u><u style="single"> The interference power monitoring means is</u><u style="single"> The monitoring of the interference power is carried out in units of the first cell in which the radio zone formed by the first radio base station is divided.</u><u style="single"> The control means</u><u style="single"> As a radio terminal to be controlled by the suppression, a second cell obtained by dividing a radio zone formed by the second radio base station and adjacent to a first cell whose monitoring result exceeds the threshold value. Select a wireless terminal located in the area,</u><u style="single">A higher-level device in the wireless communication system described in Appendix 10, wherein the device is characterized in that.</u><u style="single"> (Appendix 12)</u><u style="single"> The control means</u><u style="single"> A memory that holds information about the adjacency status of each cell formed by each radio base station, and</u><u style="single"> A specific unit that identifies the second cell adjacent to the first cell whose monitoring result exceeds the threshold value based on the information in the memory.</u><u style="single">A higher-level device in the wireless communication system described in Appendix 11, which is characterized by having the above.</u><u style="single"> (Appendix 13)</u><u style="single"> The interference power monitoring means is</u><u style="single"> The interference power is monitored based on the received power information for each of the first cells reported from the first radio base station.</u><u style="single">The higher-level device in the wireless communication system according to Appendix 11 or 12, characterized in that.</u><u style="single"> (Appendix 14)</u><u style="single"> The control means</u><u style="single"> By limiting the total transmission power of the uplink that can be allocated by the second radio base station to the radio terminal located in the second cell, the transmission power of the uplink allocated to the radio terminal is suppressed. Control,</u><u style="single">The higher-level device in the wireless communication system according to Appendix 11 or 12, characterized in that.</u><u style="single"> (Appendix 15)</u><u style="single"> The control means</u><u style="single"> The suppression control is performed by transmitting a control signal common to or individual to the radio terminals in the second cell to the second cell via the second radio base station.</u><u style="single">The higher-level device in the wireless communication system according to Appendix 11 or 12, characterized in that.</u><u style="single"> (Appendix 16)</u><u style="single"> The control means</u><u style="single"> As the wireless terminal to which the individual control signal should be transmitted, a wireless terminal located in the vicinity of the boundary with the first cell, which is a wireless terminal located in the second cell, is selected.</u><u style="single">A higher-level device in the wireless communication system described in Appendix 15, wherein the device is characterized by the above.</u><u style="single"> (Appendix 17)</u><u style="single"> The control means</u><u style="single"> The wireless terminal located near the boundary is estimated based on the signal transmitted by the wireless terminal located in the second cell.</u><u style="single">A higher-level device in the wireless communication system described in Appendix 16, wherein the device is characterized by the above.</u><u style="single"> (Appendix 18)</u><u style="single"> The control means</u><u style="single"> An adjacent cell information generation unit that generates information on the adjacency situation based on the information of a radio link formed between each radio base station and the radio terminal in the past and stores it in the memory is further provided. A higher-level device in the wireless communication system described in Appendix 12, wherein the device is characterized by the above.</u>