Uplink communication method and radio terminal in radio communication system

CROSS REFERENCE TO RELATED APPLICATION (S)

0001This application is based on and hereby claims priority to <patcit id="pcit0001" dnum="JP2006246743A"><text>Japanese Application No. 2006-246743 filed on September 12, 2006</text></patcit> in Japan, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

0002The present invention relates to an uplink communication method and a radio terminal in a radio communication system, and particularly to a technique suitable for use in a radio communication system which performs communications by radio in W-CDMA (Wideband-Code Division Multiple Access).

(2) Description of Related Art

0003W-CDMA is one of radio communication interfaces defined by IMT-2000 (International Mobile Telecommunications-2000), which is in a position of the representative radio communication system.

0004W-CDMA enables multi-media access of voice, motion pictures, data and so forth at a transmission rate of up to 384 kbps.

0005Communication systems called HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access) based on the technique of W-CDMA are under research and development in recent years.

0006In contrast to the current W-CDMA, HSPDA is a technique for performing high-speed downlink packet transmission in the down direction from a base station to a terminal (UE: User Equipment), whereas HSUPA is a technique for performing high-speed uplink packet transmission in the up direction, which is opposite to the down direction. HSDPA is standardized by 3GPP Release 5 (3rd Generation Partnership Project Release 5), and HSUPA by 3GPP Release 6.

0007FIG. 4 is a diagram showing a concept of communications in W-CDMA. As shown in FIG. 4, radio communications are performed between a base station 100 and one or a plurality of user equipments (UE) 200 in W-CDMA.

0008In the uplink, DPDCH (Dedicated Physical Data Channel), which is a channel for transmitting user information, and DFCCH (Dedicated Physical Control Channel), which is a channel for transmitting control information, are mapped to in-phase components (I axis) and quadrature phase components (Q axis) of QPSK (Quadrature Phase Shift Keying), respectively, and transmitted to the base station 100 (refer to arrows A1 indicated by solid lines).

0009In the downlink, DPDCH and DPCCH are time-division-multiplexed, and transmitted to each UE 200 (refer to an arrow A2 indicated by a broken line). Incidentally, these links are individual channels individually assigned each UE 200, on which transmission exclusive to other UEs 200 is performed.

0010FIG. 5 is a diagram showing a concept of communications in HSPDA. As shown in FIG. 5, a communication by HSDPA is performed at the time of downlink transmission from the base station 100 to the UE 200.

0011The UE 200 receives a pilot signal (signal known between the base station 100 and the UE 200) transmitted over the pilot channel (CPICH: Common Pilot Channel) from the base station 100 (refer to a reference character A5), measures propagation environments, that is, a reception quality (received signal to Interference Ratio: SIR) of the downlink on the basis of the pilot signal, calculates a CQI (Channel Quality Indicator) which is reception quality information on the downlink on the basis of a result of the measurement, and notifies the base station 100 of the CQI over HS-DPCCH (High Speed Dedicated Physical Control Channel) (refer to an arrow A3 indicated by a solid line).

0012The base station 100 carries out scheduling to select preferentially a predetermined number of UEs 200 which are in good propagation environments on the basis of the reception quality information (CQI) on the downlinks notified from the UEs 200. When a certain UE 200 is selected in this scheduling, the base station 100 notifies this UE 200 of scheduling information (including a type of modulation, transmission amount and so forth) over HS-SCCH (High Speed Shared Control Channel) (refer to an arrow A4 indicated by a broken line). The UE 200 sets its own functions on the basis of the received scheduling information.

0013Thereafter, the base station 100 transmits user information to the UE 200 over a radio channel called HS-PDSCH (High Speed Physical Downlink Shared Channel) (refer to an arrow A4 indicated by a broken line). The HS-PDSCH transmitting the user information is a common channel that the UEs 200 can share, in which one time slot obtained by time-division is shared by one or a plurality of UES 200, which enables high-speed downlink access of up to 14.4 Mpbs.

0014FIG. 6 is a diagram showing a concept of communications in HSUPA. As shown in FIG. 6, a communication by HSUPA is carried out at the time of uplink transmission from the UE 200 to the base station 100.

0015The UE 200 transmits SI (Scheduling Information) as an uplink data transmission request to the base station 100 (refer to an arrow A6 indicated by a solid line).

0016The base station 100 collects plural pieces of SI transmitted from the UEs 200, performs scheduling to determine transmission timing at which the UE 200 performs uplink transmission on the basis of the communication quality, the priority of uplink data and so forth of the UE 200, and transmits "Grant" as uplink transmission permission to the UE 200 (refer to an arrow A7 indicated by a broken line). Incidentally, "Grant" is categorized into two types, "absolute grant" and "relative grant." "Absolute grant" is used to notify of an uplink transmission rate at constant intervals, whereas "relative grant" is used to notify of update information about contents notified by "absolute grant."

0017The UEs 200 transmit user information to the base station 100 over individual channels called E-DCH (Enhanced Dedicated Channel) in the order in which the UEs 200 received uplink transmission permission obtained by receiving "Grant" from the base station 100 (refer to arrows A8 indicated by solid lines), whereby high-speed uplink access becomes feasible. Incidentally, under examination is approximately 2 to 5 Mbps of the transmission rate of E-DCH.

0018Meanwhile, HSDPA adopts the adaptive coding modulation, which is characterized by that the QPSK and the 16QAM are adaptively switched according to radio environments between the base station 100 and the UE 200. In order to realize the above adaptive modulation system, the CQI is defined to report reception environments from the UE 200 to the base station 100. In the CQI table, there is defined a format of different transmission rates to CQI=1 to 30, for example.

0019The UE 200 measures the reception environments, and reports the base station 100 of the largest CQI or a CQI smaller than the largest CQI not exceeding BLER (Block Error Rate)= 0.1 of HS-PDSCH assuming that the UE 200 having been received the HS-PDSCH within three slots preceding a slot in which the UE 200 transmits the CQI under the above environments.

0020In the HSUPA, the base station 100 monitors a total uplink interference amount (receive power) of UEs 200 in the service area of the base station 100, compares the receive power with a threshold value, indicates a transmission rate of an absolute value to the UE 200 by using E-AGCH (command designating an absolute value of the maximum rate), or directs the UE 200 to increase, keep or decrease the transmission rate by using E-RGCH (command designating a relative value of the maximum rate). When having uplink transmission data, the UE 200 transmits an SI (scheduling request) to the base station 100.

0021There are a non-patent document 1 below as the latest material with respect to physical channel and transport channel relating to W-CDMA including HSUPA, and a non-patent document 2 below as the latest material with respect to physical layer of HSUPA. <ul id="ul0001" list-style="none" compact="compact"><li>[Non-patent Document 1] 3GPP TR 25.211 Release 7 (V7.0.0)(2006-03)</li><li>[Non-patent Document 2] 3GPP TR 25.808 Release 6 (V6.0.0) (2005-03)</li></ul>

0022FIG. 7 shows an example of constitution of essential parts of a UE 200 having a transmitting function of the SI (scheduling request). The UE 200 shown in EIG. 7 comprises, for example, a receiver 201, an HS-SCCH demoulator 202, an HS-SCCH decoder 203, an HS-PDSCH demodulator 204, a CQI report value calculator 205, an HS-PDSCH decoder 206, an HS-PDSCH CRC operator 207, a downlink layer 2 (L2) data processor 208, a downlink reception timing monitoring/uplink transmission timing managing unit 209, a CQI/ACK/NACK scheduler 210, an HS-DPCCH coder 211, an HS-DPCCH modulator 212, an uplink layer 2 (L2) data processor 213, an uplink scheduling request processor 214, an E-DCH coding processor 215, an E-DCH modulator 216 and a transmitter 217.

0023In the UE 200 having the above structure, a signal received by a receiving antenna (not shown) is inputted to the receiver 201. In the receiver 201, path detection, despreading process and so forth are performed on the signal to separate it to channels of CPICH, HS-SCCH and HS-PDSCH.

0024The CPICH (pilot signal) among them is inputted to the CQI report value calculator 205 to be used to calculate a CQI report value. Namely, a reception SIR is measured on the basis of the received pilot signal, and a CQI of the downlink is calculated on the basis of a result of the measurement. The CQI is passed through the CQI/ACK/NACK scheduler (hereinafter, referred to simply as "scheduler" occasionally) 210, the HS-DPCCH coder 211, the HS-DPCCH modulator 212 and the transmitter 217 to be undergone the coding process, the modulation process and the radio transmission process, and notified to the base station 100 over HS-DPCCH. Incidentally, the received pilot signal is also used to determine channel estimation values of the HS-SCCH and the HS-PDSCH.

0025The HS-SCCH separated in the receiver 201 is compensated by using the channel estimation value obtained on the basis of the received pilot signal, demodulated, and decoded by the HS-SCCH decoder 203. A result of the decoding is inputted to the HS-PDSCH decoder 206 because it includes information (coding method, coding rate, etc.) necessary to decode the HS-PDSCH.

0026The HS-PDSCH separated in the receiver 201 is compensated by using the channel estimation value by the HS-PDSCH demodulator 204, decoded by the HS-PDSCH decoder 206 by using a result of the decoding fed from the HS-SCCH decoder 203, and undergone the CRC operation to be error-checked by the HS-PDSCH CRC operator 207.

0027Decoded data free from an error [whose result of the CRC operation is all correct (OK)] is inputted as received data of the downlink layer 2 to the L2 data processor 208, and undergone a necessary L2 data processing. The result of the CRC operation is inputted to the scheduler 210, wherein ACK information is scheduled when the result of the CRC operation is OK, or NACK information when the result of the CRC operation is no good (NG), together with the above CQI report value, passed through the HS-DPCCH coder 211, the HS-DPCCH modulator 212 and the transmitter 217 to be undergone the coding process, the modulation process and the radio transmission process, and notified to the base station 100 over the HS-DPCCH.

0028With respect to the uplink, when uplink L2 data to be transmitted to the base station 100 is present in the uplink L2 data processor 213, an uplink SI is generated by the uplink scheduling request processor 214, the SI is passed through the E-DCH coding processor 215, the E-DCH modulator 216 and the transmitter 217 to be undergone the coding process, the modulation process and the radio transmission process, and transmitted to the base station 100 over the E-DCH.

0029Meanwhile, transmission timing of the HS-DPCCH and E-DCH by the transmitter 217 is managed on the basis of transmission timing signals fed from the downlink reception timing monitoring/uplink transmission timing managing unit (hereinafter, referred to simply as "timing managing unit" occasionally) 209. Namely, the timing managing unit 209 manages transmission timing (transmission slots) of the HS-DPCCH and E-DCH on the basis of reception timing (frame timing) specified in the frame synchronization process in the receiver 201, and controls so that the transmission timing by the transmitter 217 agrees with specified timing according to the transmission timing.

0030Next, description will be made of uplink transmission power-to-throughput characteristics which vary according to differences in environments such as a distance and the like between the UE 200 and the base station 100, with reference to FIG. 8. In FIG. 8, reference character 100a denotes a radio area (cell) formed by the base station 100, reference character 200-1 a UE located in a place (in the vicinity of the cell boundary: location A) far away from the base station 100, and reference character 200-2 a UE located in a place (location B) near the base station 100.

0031In the case where the same amount of data is regularly transmitted from each of the UE 200-1 and the UE 200-2, for example, the UE 200-2 can obtain a sufficient throughput even if the transmission electric power of E-DCH is small since a distance between the UE 200-2 and the base station 100 is small.

0032However, the UE 200-1 needs a higher transmission electric power of E-DCH in order to transmit uplink data to the base station 100 at a high throughput since a distance between the UE 200-1 and the base station 100 is large. For this, the UE 200-1 consumes a large electric power, and generates a large interference wave with radio communication equipments around the UE 200-1, at the same time.

0033As described above, in the HSUPA communication, the UEs 200 requesting for uplink data transmission transmit SIs as uplink data transmission requests to the base station 100, whereas the base station 100 collects a plurality of the SIs transmitted from the UEs 200, and performs scheduling to determine transmission timing by the UEs 200 which intend to perform uplink transmission on the basis of the communication quality, the priority of the uplink data, etc. of the UEs. Thus, it can be said that the HSUPA communication has in nature high system throughput efficiency.

0034However, in ordinary HSUPA communication, the base station 100 gives permission to even a UE 200 in poor reception environments which desires to perform uplink transmission when there is no other UE 200 making a transmission request, so the UE 200 initiates the communication. In a bad case, the communication is initiated in environments of a poor reception quality, the reception quality is further deteriorated thereafter, and the communication is terminated before the data transmission is completed, after all. This leads to deterioration of the power consumption efficiency of the UE 200, and causes interference with other radio communication equipments.

SUMMARY OF THE INVENTION

0035In the light of the above problems, an object of the present invention is to control transmission timing of a request for obtaining, from a radio base station, permission to transmit an uplink signal, thereby obtaining an expected throughput and suppress interference with other radio communication equipments while decreasing the transmission electric power of a radio terminal.

0036To attain the above object, the present invention is characterized by using an uplink communication method and a radio terminal in a radio communication system below. Namely, <ol id="ol0001" compact="compact" ol-style=""><li>(1) An uplink communication method in a radio communication system comprising a radio base station and a radio terminal communicating with the radio base station, comprising the steps of (a) estimating, in the radio terminal, a reception quality of an uplink signal at the radio base station based on a downlink signal received from the radio base station, and (b) controlling, in the radio terminal, transmission timing of a transmission request to the radio base station to obtain permission of transmitting the uplink signal based on a result of estimation at the estimating step (a).</li><li>(2) A radio terminal in a radio communication system comprising a radio base station and the radio terminal communicating with the radio base station by radio, comprising a transmitting means being able to transmit a transmission request for permission of transmitting an uplink signal to the radio base station, an uplink reception quality estimating means for estimating a reception quality of the uplink signal at the radio base station based on a downlink signal received from the radio base station, and an uplink transmission timing controlling means for controlling the transmitting means based on a result of estimation by the up reception quality estimating means to control transmission timing for the transmission request to the radio base station.</li><li>(3) The uplink transmission timing controlling means may control the transmitting means in such a way as to transmit the transmission request upon the result of estimation being equal to or greater than a predetermined uplink quality threshold value, while wait transmission of the transmission request upon the result of estimation being below the uplink quality threshold value.</li><li>(4) The uplink transmission timing controlling means may further comprise a transmission electric power value monitoring unit for monitoring a current uplink transmission electric power value, and a transmission electric power determining unit for determining whether a result of monitoring by the transmission electric power value monitoring unit is below a predetermined transmission electric power threshold value, wherein the uplink transmission timing controlling unit controls the transmitting means in such a way as to transmit the transmission request when the transmission electric power determining unit determines that the result of monitoring is below the transmission electric power value, while wait transmission of the transmission request when the result of estimation is equal to or greater than the transmission electric power threshold value.</li><li>(5) The uplink transmission timing controlling means may further comprise a waiting time monitoring unit for monitoring a waiting time upon transmission of the transmission request being waited, and a waiting time determining unit for determining whether the waiting time monitored by the waiting time monitoring unit exceeds a predetermined time period, wherein the uplink transmission timing controlling means controls the transmitting means in such a way as to transmit the transmission request when the waiting time determining unit determines that the waiting time exceeds the predetermined time period.</li><li>(6) The uplink transmission timing controlling means may further comprise a battery remaining quantity monitoring unit for monitoring a battery remaining quantity, and a battery remaining quantity determining unit for determining whether a result of monitoring by the battery remaining quantity monitoring unit is equal to or greater than a predetermined battery threshold value, wherein the uplink transmission timing controlling means controls the transmitting means in such a way as to transmit the transmission request when the battery remaining quantity determining unit determines that the result of monitoring is equal to or greater than the battery threshold value.</li><li>(7) The uplink transmission timing controlling means may further comprise a battery remaining quantity monitoring unit for monitoring a battery remaining quantity, wherein the uplink transmission timing controlling means controls the result of estimation in such a way that the smaller the battery remaining quantity, the harder the transmission request is transmitted.</li><li>(8) The uplink transmission timing controlling means may further comprise an inputting unit for accepting input information about the transmission timing by a user of the radio terminal, wherein the uplink transmission timing controlling means controls the transmission timing based on the input information inputted through the inputting unit.</li></ol>

0037The present invention provides at least any one of effects and advantages below: <ol id="ol0002" compact="compact" ol-style=""><li>(1) The radio terminal estimates a reception quality of an uplink signal at the radio base station (hereinafter referred to simply as "base station") based on the downlink signal received from the base station, and controls transmission timing of a transmission request to the base station to obtain permission to transmit the uplink signal based on the result of the estimation. Whereby, transmission of the transmission request of the uplink signal can be waited when reception environments at the base station are estimated to be poor, and the transmission request can be transmitted when the reception environments at the base station are estimated to be good. Accordingly, it is possible to suppress a transmission electric power of the radio terminal to low, obtain an expected throughput, and reduce interference with other radio communication equipments.</li><li>(2) A transmission electric power of the current uplink signal is monitored to determine whether to issue the transmission request of the uplink signal according to a result of the monitoring. This enables a reduction power consumption of the radio terminal.</li><li>(3) When a waiting time of the uplink signal exceeds a predetermined time period, it is possible to decide to issue a transmission request. Whereby, it becomes possible to avoid a case where the transmission request is not transmitted indefinitely, thus a communication is not initiated, after all.</li><li>(4) The transmission timing can be controlled based on input information relating to transmission timing of the transmission request from the user through the inputting unit. Accordingly, it is possible to appropriately change the transmission timing of the transmission request according to convenience (will) of the user, which leads to improvement of utility for the user.</li><li>(5) A battery remaining quantity of the radio terminal is monitored, and the smaller the battery remaining quantity, the harder the transmission request is transmitted. This is helpful to further reduce the power consumption of the radio terminal.</li></ol>

0038The above and other objects and features of the present invention will be understood by reading carefully the following description with accompanying drawings. Preferred embodiments of the present invention will be described in more detail referring to the accompanying drawings. The drawings are illustrative and are not to be limitative of the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

0039<ul id="ul0002" list-style="none" compact="compact"><li>FIG. 1 is a diagram schematically showing a structure of a mobile communication system according to an embodiment of this invention;</li><li>FIG. 2 is a block diagram showing an essential structure of a radio terminal (UE) shown in FIG. 1;</li><li>FIG. 3 is a flowchart for illustrating an operation of the UE shown in FIG. 2 at the time of uplink communication;</li><li>FIG. 4 is a diagram showing a concept of communications in W-CDMA;</li><li>FIG. 5 is a diagram showing a concept of communications in HSDPA;</li><li>FIG. 6 is a diagram showing a concept of communications in HSUPA;</li><li>FIG. 7 is a block diagram showing an example of an essential structure having an SI (scheduling request) transmitting function in the HSUPA communication; and</li><li>FIG. 8 is a diagram showing a concept of transmission electric power characteristics in environments of the UE.</li></ul>

DESCRIPTION OF THE PREFERRED EMBODIMENTS

0040Preferred embodiments of the present invention are described in more detail below referring to the accompanying drawings.

[A] Explanation of Outline

0041FIG. 1 is a diagram schematically showing a structure of a mobile communication system according to an embodiment of this invention. The mobile communication system shown in FIG. 1 comprises a radio base station (BTS: Base Transceiver Station) 1, and a mobile station (MS: Mobile Station) as being a radio (user) terminal (UE) such as a cellular phone being capable of radio communication with the BTS 1 within a radio area (cell) 1a formed by the BTS 1. In this embodiment, it is assumed that downlink communication from the BTS 1 to the MS (occasionally referred to as UE) 2 is performed in HSDPA, whereas uplink communication from the MS 2 to the BTS 1 is performed in HSUPA. Incidentally, the number of the BTSs 1 may be one or more, as well as the MSs 2.

0042The reception quality at the BTS 1 of transmission data (hereinafter referred to as uplink transmission data or uplink data occasionally) in the uplink (E-DCH) from the UE 2 to the BTS 1 tends to be deteriorated due to effects by multi-path environments such as a distance between the UE 2 and the BTS 1, buildings near the UE 2, etc, in general. Similarly, the reception quality at the UE 2 of data in the downlink tends to be deteriorated due to effects of multi-path environments such as a distance between the BTS 1 and the UE 2, etc. Accordingly, it is possible to estimate the reception quality at the BTS 1 of data (user information) in the uplink (E-DCH) on the basis of a CQI report value representing the reception quality of the HS-PDSCH in the downlink, for example.

0043Therefore, the UE 2 located in a place (location) C away from the BTS 1 such as a place on the cell boundary shown in FIG. 1 refers to a CQI representing the reception environments of the downlink. When the CQI is low, the UE 2 stores (holds) uplink transmission data in a memory or the like thereof, waits to transmit an uplink data scheduling request (SI). When moving to a place where the CQI is high such as a place (location) D near the BTS 1, the UE 2 transmits the uplink data scheduling request (SI) to transmit a request of the uplink transmission data stored in the memory.

0044As this, when the UE 2 has uplink transmission data to be transmitted to the BTS 1, the UE 2 estimates the reception environments at the BTS 1 at the time of E-DCH transmission on the basis of the CQI. When determining that the reception environments at the BTS 1 are poor, the UE 2 stores the uplink transmission data in a memory or the like thereof, and waits to transmit the SI. When estimating that the reception environments at the BTS 1 are good, the UE 2 transmits the SI. Whereby, it is possible to hold down the transmission electric power of the UE 2, and obtain an expected throughput. It is also possible to reduce the interference with other radio communication equipments.

0045In the known technique, when the UE has an uplink data to be transmitted to the BTS 1, the UE 2 transmits an SI to the BTS 1 even in environments where the UE 2 needs a large electric power to transmit E-DCH to the BTS 1 because the UE 2 is in a place away from the BTS 1 such as a location C.

0046Hereinafter, description will be made of an example where the UE 2 having the above SI transmission/wait controlling function is realized.

[B] Description of UE 2

0047FIG. 2 is a block diagram where attention is given to essential constitution of the above UE 2. The UE 2 shown in FIG. 2 comprises, for example, a receiver 21, an HS-SCCH modulation processor 22, an HS-SCCH decoding processor 23, an HS-PDSCH demodulation processor 24, a CQI report value calculator 25, an HS-PDSCH decoder 26, an HS-FDSCH CRC operator 27, a downlink L2 (Layer 2) data processor 28, a downlink reception timing monitoring/uplink transmission managing unit 29, a CQI/ACK/NACK scheduler 30, an HS-DPCCH coder 31, an HS-DPCCH modulator 32, an uplink L2 data processor 33, an uplink E-DCH reception environment estimator 34, a memory (uplink data storing unit) 35, an uplink L2 data transmission request determining unit 36, an uplink scheduling request processor 37, an E-DCH coding processor 38, an E-DCH modulation processor 39 and a transmitter 40.

0048The above parts 21 through 33 and 37 through 40 excepting the uplink E-DCH reception environment estimator 34, the uplink data storing unit 35 and the uplink L2 data transmission request determining unit 36 have functions equivalent to those of the parts 201 through 217 described above with reference to FIG. 7, respectively.

0049The receiver 21 performs the path detection, the despreading process and so forth based on a signal received by a receiving antenna (not shown), and separates the received signal to channels (signals) of CPICH, HS-SCCH and HS-PDSCH. The HS-SCCH demodulation processor 22 compensates the above received HS-SCCH on the basis of a channel estimation value of the downlink determined from the above CPICH (pilot signal), then demodulates the signal in a demodulation method corresponding to a modulation method (multi-value modulation method such as QPSK; the same will be applied hereinafter) on the transmitting side (BTS 1). The HS-SCCH decoding processor 23 decodes the signal demodulated by the HS-SCCH demodulation processor 22 in a decoding method corresponding to a coding method (error correction coding method such as convolutional coding, turbo coding and the like; the same will be applied hereinafter) on the transmitting side. Since, a result of this decoding includes information (coding method, coding rate, etc.) necessary for demodulation of the HS-PDSCH, the result is supplied to the HS-PDSCH decoder 26.

0050The CQI report value calculator 25 calculates a CQI report value (hereinafter referred to simply as "CQI", occasionally) on the basis of the received pilot signal. For example, the CQI report value calculator 25 can measure a received SIR of the downlink on the basis of the received pilot signal, and calculate a CQI report value of the downlink on the basis of a result of this measurement. The calculated CQI is supplied to both the CQI/ACK/NACK scheduler 30 and the uplink E-DCH reception environment estimator 34.

0051The HS-PDSCH demodulation processor 24 compensates the received HS-PDSCH separated by the receiver 21 by using the channel estimation value, then demodulates it in a demodulation method corresponding to the modulation method on the transmitting side (BTS 1). The HS-PDSCH decoder 26 decodes the demodulated signal by using the result of demodulation fed from the HS-SCCH decoding processor 23. The HS-PDSCH CRC operator 27 performs the CRC operation on a result of the decoding to check an error, whereby decoded data free of an error [whose result of the CRC operation is all correct (OK)] is outputted as received data of the downlink layer 2 to the downlink L2 data processor 28. Incidentally, a result of this CRC operation is also inputted to the scheduler 30, in which transmission timing of ACK information or NACK information to the BTS 1 is scheduled together with the CQI report value calculated by the CQI report value calculator 25.

0052The downlink L2 data processor 28 performs a necessary process of Layer 2 on decoded data (downlink L2 data) the result of CRC operation on which is OK.

0053The downlink reception timing monitoring/uplink transmission managing unit (hereinafter referred to simply as "timing managing unit") 29 manages transmission timing (transmission slot) of the uplink channels (HS-DPCCH and E-DCH) on the basis of reception timing (frame timing) specified in the frame synchronization process by the receiver 21, and controls according to the transmission timing so that the transmission timing by the transmitter 40 is specified timing.

0054The CQI/ACK/NACK scheduler (hereinafter, referred to simply as "scheduler") 30 schedules the transmission timing of the CQI report value calculated by the CQI report value calculator 25 and the ACK/NACK information according to the result of CRC operation to the BTS 1. The HS-DPCCH coder 31 encodes information scheduled by the scheduler 30 and to be transmitted over the HS-DPCCH in a necessary coding method (error correction coding method). The HS-DPCCH modulator 32 modulates the coded information in a necessary modulation method.

0055The uplink L2 data processor 33 generates and processes uplink data of Layer 2 to be transmitted to the BTS 1. The uplink L2 data scheduling request processor 37 generates and processes an uplink scheduling request (SI) to be transmitted to the BTS 1 over the E-DCH when the uplink L2 data transmission request determining unit (hereinafter, referred to simply as "transmission request determining unit") 36 to be described later determines that the uplink scheduling request (SI) is transmitted to the BTS 1.

0056The E-DCH coding processor 38 encodes the SI fed from the uplink scheduling request processor 37 as information on the E-DCH in a necessary coding method. The E-DCH modulation processor 39 modulates the encoded information in a necessary modulation system.

0057The transmitter 40 performs necessary radio transmission processes such as DA (Digital to Analog) conversion, frequency conversion to a radio frequency (RF) (up-conversion) and so forth on modulated signals on the HS-DPCCH and E-DCH obtained by the HS-DPCCH modulator 32 and the E-DCH modulation processor 39, respectively, and transmits the signals on the channels of the uplink from a transmitting antenna (not shown) to the BTS 1 according to the transmission timing signals from the timing managing unit 29.

0058Namely, the uplink scheduling request processor 37, the E-DCH coding processor 38, the E-DCH modulation processor 39 and the transmitter 40 together function as a transmitting means which can transmit a transmit request (SI) for obtaining transmission permission ("Grant") of an uplink signal to the BTS 1.

0059The uplink E-DCH reception timing environment estimator (uplink reception quality estimating means) 34 estimates a reception quality of an uplink signal at the BTS 1 on the basis of a downlink signal received from the BTS 1. In this embodiment, the uplink E-DCH reception environment estimator 34 estimates reception environments (quality) of the uplink (E-DCH) at the BTS 1 on the basis of the CQI report value of the downlink calculated by the CQI report value calculator 25. For example, it is possible to estimate a transmission throughput of the E-DPDCH (physical channel relative to E-DCH which is a logical channel), that is, reception environments (quality) of the E-DPDCH at the BTS 1, on the basis of a table 1 below in which a CQI is correlated to at least a reception throughput (kbps) of the HS-PDSCH at the UE (MS) 2.

0060Namely, the CQI report value is a value that assures 90% [block error rate (BLER) = 0. 1] of a reception throughput of the UE 2 to a transport block size of HS-PDSCH corresponding to the CQI report value that the BTS 1 transmits (refer to a table 1 below). Since communication environments of E-DPDCH of the uplink are assumed to have high correlation with communication environments of HS-PDSCH of the downlink, it is possible to assume that the transmission throughput of E-DPDCH of the uplink of the UE 2 is equivalent to the reception throughput of HS-PDSCH of the downlink (that is, finally, it becomes possible to estimate a corresponding CQI from the table 1 below).

0061With respect to the CQI, a value obtained by averaging values over a certain period cf time may be used as a base of the above determination reference. In which case, the uplink E-DCH reception environment estimator 34 has an averaging process functioning unit 341 (refer to FIG. 2) which averages CQIs calculated by the CQI report value calculator 25 over a certain period of time. <tables id="tabl0001" num="0001"><table frame="all"><title>[Table 1]</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="11mm" /><colspec colnum="2" colname="col2" colwidth="32mm" /><colspec colnum="3" colname="col3" colwidth="62mm" /><colspec colnum="4" colname="col4" colwidth="62mm" /><thead><row><entry namest="col1" nameend="col4" align="center" valign="top">CQI to HS-PDSCH MS reception throughput</entry></row><row><entry align="center" valign="top">CQI</entry><entry align="center" valign="top">transport block size</entry><entry align="center" valign="top">HS-PDSCH BTS transmission rate [kbps]</entry><entry align="center" valign="top">HS-PDSCH MS reception throughput [kbps]</entry></row></thead><tbody><row><entry align="center">1</entry><entry align="center">137</entry><entry align="center">69</entry><entry align="center">62</entry></row><row><entry align="center">2</entry><entry align="center">173</entry><entry align="center">87</entry><entry align="center">78</entry></row><row><entry align="center">3</entry><entry align="center">233</entry><entry align="center">117</entry><entry align="center">105</entry></row><row><entry align="center">4</entry><entry align="center">317</entry><entry align="center">159</entry><entry align="center">143</entry></row><row><entry align="center">5</entry><entry align="center">377</entry><entry align="center">189</entry><entry align="center">170</entry></row><row><entry align="center">6</entry><entry align="center">461</entry><entry align="center">231</entry><entry align="center">207</entry></row><row><entry align="center">7</entry><entry align="center">650</entry><entry align="center">325</entry><entry align="center">293</entry></row><row><entry align="center">8</entry><entry align="center">792</entry><entry align="center">396</entry><entry align="center">356</entry></row><row><entry align="center">9</entry><entry align="center">931</entry><entry align="center">466</entry><entry align="center">419</entry></row><row><entry align="center">10</entry><entry align="center">1262</entry><entry align="center">631</entry><entry align="center">568</entry></row><row><entry align="center">11</entry><entry align="center">1483</entry><entry align="center">742</entry><entry align="center">667</entry></row><row><entry align="center">12</entry><entry align="center">1742</entry><entry align="center">871</entry><entry align="center">784</entry></row><row><entry align="center">13</entry><entry align="center">2279</entry><entry align="center">1140</entry><entry align="center">1026</entry></row><row><entry align="center">14</entry><entry align="center">2583</entry><entry align="center">1292</entry><entry align="center">1162</entry></row><row><entry align="center">15</entry><entry align="center">3319</entry><entry align="center">1660</entry><entry align="center">1494</entry></row><row><entry align="center">16</entry><entry align="center">3565</entry><entry align="center">1783</entry><entry align="center">1604</entry></row><row><entry align="center">17</entry><entry align="center">4189</entry><entry align="center">2095</entry><entry align="center">1885</entry></row><row><entry align="center">18</entry><entry align="center">4664</entry><entry align="center">2332</entry><entry align="center">2099</entry></row><row><entry align="center">19</entry><entry align="center">5287</entry><entry align="center">2644</entry><entry align="center">2379</entry></row><row><entry align="center">20</entry><entry align="center">5887</entry><entry align="center">2944</entry><entry align="center">2649</entry></row><row><entry align="center">21</entry><entry align="center">6554</entry><entry align="center">3277</entry><entry align="center">2949</entry></row><row><entry align="center">22</entry><entry align="center">7168</entry><entry align="center">3584</entry><entry align="center">3226</entry></row><row><entry align="center">23</entry><entry align="center">9719</entry><entry align="center">4860</entry><entry align="center">4374</entry></row><row><entry align="center">24</entry><entry align="center">11418</entry><entry align="center">5709</entry><entry align="center">5138</entry></row><row><entry align="center">25</entry><entry align="center">14411</entry><entry align="center">7206</entry><entry align="center">6485</entry></row><row><entry align="center">26</entry><entry align="center">17237</entry><entry align="center">8619</entry><entry align="center">7757</entry></row><row><entry align="center">27</entry><entry align="center">21754</entry><entry align="center">10877</entry><entry align="center">9789</entry></row><row><entry align="center">28</entry><entry align="center">23370</entry><entry align="center">11685</entry><entry align="center">10517</entry></row><row><entry align="center">29</entry><entry align="center">24222</entry><entry align="center">12111</entry><entry align="center">10900</entry></row><row><entry align="center">30</entry><entry align="center">25558</entry><entry align="center">12779</entry><entry align="center">11501</entry></row></tbody></tgroup></table></tables>

0062In other words, the E-DCH reception environment estimator 34 of this embodiment has a function as a CQI estimating unit 342 (refer to FIG. 2) which determines a CQI, which is reception quality information on a downlink signal, as a result of estimation of the reception quality of an uplink signal. Further, the CQI estimating unit 342 has functions as an uplink transmission data speed estimating unit which estimates a transmission data speed (transmission throughput) of a transmittable uplink signal on the basis of a reception data speed (reception throughput) of the downlink signal, and a converting unit which converts the transmission data speed estimated by the uplink transmission data speed estimating unit to a corresponding CQI in the above table 1. The table 1 is retained as data in a table form in an integrated memory or the like not shown of the E-DCH reception environment estimator 34, for example.

0063When uplink transmission data fed from the uplink L2 data processor 33 is present, the transmission request determining unit 36 determines (decides) on the basis of at least a result of the estimation by the uplink E-DCH reception environment estimator 34 whether to issue an uplink scheduling request (SI) (hereinafter referred to as uplink transmission request, occasionally) to the BTS 1. For example, when the transmission throughput of E-DCH is assumed to be below a predetermined threshold value (for example, 200 kbps) by the uplink E-DCH reception environment estimator 34 (that is, when CQI = 1 to 5 in the table 1), the transmission request determining unit 36 determines not to issue an uplink transmission request, as shown in table 2 below. In cases excepting the above case (in the case where CQI = 6 to 30 in the table 1), the transmission request determining unit 36 determines to issue the uplink transmission request. Incidentally, the above threshold value is defined and set in a view point that the throughput is sufficient to complete normally the communication. <tables id="tabl0002" num="0002"><table frame="all"><title>[Table 2]</title><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="44mm" /><colspec colnum="2" colname="col2" colwidth="52mm" /><thead><row><entry namest="col1" nameend="col2" align="left" valign="top">Example of determination reference of uplink transmission request</entry></row><row><entry align="center" valign="top">CQI</entry><entry align="center" valign="top">Uplink transmission request</entry></row></thead><tbody><row><entry align="center">1-5</entry><entry align="center">not issued</entry></row><row><entry align="center">6-30</entry><entry align="center">issued</entry></row></tbody></tgroup></table></tables>

0064The uplink data storing unit (signal retaining unit) 35 temporarily holds uplink transmission data, the uplink transmission request of which is determined not to be made (to be waited) by the transmission request determining unit 36.

0065Namely, the uplink data storing unit 35 and the transmission request determining unit 36 of this embodiment together function as an uplink transmission timing controlling means which controls the above parts 37 to 39 and the transmitter 40 as being the above transmitting means on the basis of a result of estimation by the uplink E-DCH reception environment estimator 34 to control uplink transmission timing of an uplink SI to the BTS 1.

0066Note that the transmission request determining unit 36 of this embodiment may selectively and additionally have functions below (refer to FIG. 2) <ol id="ol0003" compact="compact" ol-style=""><li>(1) an uplink transmission electric power monitoring function unit 361 which monitors a transmission electric power of the uplink (DPDCH), and adds a result of the monitoring as an element of the above determination reference (reference to decide whether to issue an uplink transmission request) (for example, deciding to issue an uplink transmission request when the transmission electric power is not the maximum electric power);</li><li>(2) a timer function unit 362 which monitors a time period for which uplink data is stored in the uplink data storing unit 35, and adds a result of the monitoring as an element of the above determination reference (for example, determining to issue an uplink transmission request when the storing time exceeds a predetermined time period (transmission limit time period);</li><li>(3) a user interface function unit (inputting unit) 363 which accepts a determination condition relating to an uplink transmission request from a user of the UE 2 (that is, input information relating to transmission timing of the uplink transmission request such as whether the uplink transmission request can be waited, the above transmission limit time period or the like), and adds it as an element of the determination reference; and</li><li>(4) a battery monitoring function unit 364 which monitors a remaining quantity of a battery of the UE 2, and adds a result of the monitoring as an element of the determination reference (for example, the smaller the remaining quantity of the battery, the harder the uplink transmission request is transmitted).</li></ol>

0067Now, description will be made in more detail an operation of the UE 2 having the above structure according to this embodiment.

(B1) Explanation of Whole Operation

0068In the UE 2 having the above structure, a signal received by the receiving antenna is inputted to the receiver 21. In the receiver 21, path detection, despreading process and so forth are performed on the signal to separate it into channels of CPICH, HS-SCCH and HS-PDSCH.

0069The CPICH (pilot signal) among them is inputted to the CQI report value calculator 25, and used to calculate a CQI report value. Namely, a received SIR of the downlink is measured on the basis of the received pilot signal, and a CQI of the downlink is calculated on the basis of a result of the measurement. The CQI is routed through the scheduler 30, the HS-DPCCH coder 31, the HS-DPCCH modulator 32 and the transmitter 40 to be undergone the coding process, the modulation process and the radio transmission process, and notified to the BTS 1 over HS-DPCCH.

0070The HS-SCCH separated by the receiver 21 is compensated by using a channel estimation value obtained on the basis of the received pilot signal and demodulated by the HS-SCCH demodulation processor 22, then decoded by the HS-SCCH decoding processor 23. A result of the decoding is inputted to the HS-PDSCH decoder 26 because the result includes information (coding method, coding rate and so forth) necessary to decode the HS-PDSCH.

0071The HS-PDSCH separated by the receiver 21 is compensated by using the channel estimation value and demodulated by the HS-PDSCH demodulation processor 24, decoded by using the decoding result fed from the HS-SCCH decoding processor 23 by the HS-PDSCH decoder 26, and undergone the CRC operation to be error-checked or the HS-PDSCH CRC operator 27.

0072As a result, decoded data free of an error (a result of the CRC operation thereon being OK) is inputted as received data of the downlink Layer 2 to the downlink L2 data processor 28, and undergone a necessary L2 data processing. A result of the CRC operation is inputted to the scheduler 30.

0073The scheduler 30 schedules ACK information when a result of the CRC operation is OK, or NACK information when a result of the CRC operation is NG, together with the above CQI report value. The scheduled information is passed through the HS-DPCCH coder 31, the HS-DPCCH modulator 32 and the transmitter 40 to be undergone the coding process, the modulation process and the radio transmission process, and notified to the BTS 1 over the HS-DPCCH.

0074The uplink E-DCH reception environment estimator 34 estimates reception environments of the uplink E-DCH on the basis of the above CQI as described above with reference to the table 1. A result of the estimation is provided to the transmission request determining unit 36.

0075With respect to the uplink, when any uplink transmission data to be transmitted to the BTS1 is present in the uplink L2 data processor 33, the transmission request determining unit 36 determines (decides) whether to transmit an uplink transmission request (SI) or to wait transmission of the uplink transmission request (SI) on the basis of at least the estimation result. When the transmission request determining unit 36 decides to transmit, the uplink scheduling request processor 37 generates an uplink SI. The uplink SI is passed through the E-DCH coding processor 38, the E-DCH modulation processor 39 and the transmitter 40 to be undergone the coding process, the modulation process and the radio transmission process, and transmitted to the BTS 1 over the E-DCH according to a transmission timing signal fed from the timing managing unit 29. To the contrary, when the transmission determining unit 33 decides to wait transmission of the SI, the uplink data is held in the uplink data storing unit 35.

(B2) Explanation of Uplink Transmission Request Determination Operation

0076Next, description will be made of a determining method (operation of determining transmission/wait of the uplink transmission request) by the transmission request determining unit 36 with reference to a flowchart shown in FIG. 3.

0077As shown in FIG. 3, the transmission request determining unit 36 monitors presence/absence of uplink transmission data to be transmitted from the uplink L2 data processor 33 (No route at step S1). When uplink transmission data is present (when Yes at step S1), the transmission request determining unit 36 measures an amount of the uplink transmission data (step S2) to determine whether transmission of the up transmission data can be waited (step S3).

0078Namely, the transmission request determining unit 36 determines whether to transmit or wait according to setting information on the data (such as an E-mail in a large amount) by the user representing whether the user desires to immediately transmit it or the user can wait to transmit it. The setting information can be input, accepted and set by that the use interface function unit 363 displays a screen that prompts the user to input the setting information on a display (display unit: not shown) of the UE 2, for example.

0079When it is determined as a result of the determination that transmission of the data cannot be waited (that is, data is to be immediately transmitted) (when No at step S3), the transmission request determining unit 36 directs the uplink scheduling request processor 37 to transmit an uplink SI. Whereby, the uplink SI is transmitted to the BTS 1 via the uplink scheduling request processor 37, the E-DCH coding processor 38, the E-DCH modulation processor 39 and the transmitter 40 (step S4).

0080When it is determined that transmission of the uplink transmission data can be waited (when Yes at step S3), the transmission request determining unit 36 holds the uplink transmission data in the uplink data storing unit 35 (step S5), calculates a transmission throughput necessary for the uplink transmission on the basis of the measured data amount (step S6), and determines a CQI corresponding to this transmission throughput as a CQI threshold value (that is, CQI which is a boundary value used as the determination reference in the table 2: uplink quality threshold value) from the table 1 (step S7).

0081The transmission request determining unit 36 further determines whether the current battery remaining quantity is less than a predetermined threshold value (battery threshold value) and is thus small, by means of the battery monitoring function unit 364 (step S8). When the current battery remaining quantity is small (when Yes at step S8), the transmission request determining unit 36 increases the CQI threshold value by a predetermined number (or by one, or by two or more at a time) (step S9). This means that the transmission request determining unit 36 controls to increase the range of the CQI, at which the up transmission request is not issued in the table 2, when the battery remaining quantity is small so that the smaller the battery remaining quantity, the harder the uplink transmission request is transmitted (that is, the chance to transmit the uplink transmission request is lessened). Incidentally, when the battery remaining quantity is sufficiently large, the process of increasing the CQI threshold value is not carried out (No route at step S8).

0082Namely, the transmission request determining unit 36 has functions as both a battery remaining quantity monitoring unit which monitors the battery remaining quantity, and a battery remaining quantity determining unit which determines whether a result of the monitoring by the battery remaining quantity monitoring unit is not less than a predetermined battery threshold value. When the battery remaining quantity determining unit determines that a result of the monitoring is not less than the battery threshold value, the transmission request determining unit 36 controls so that the transmitting means 37 through 40 can transmit the uplink transmission request.

0083The transmission request determining unit 36 then determines by means of the timer function unit 362 whether the storing time of the uplink transmission data stored in the uplink data storing unit 35 exceeds a transmission limit time period or not (step S10). The transmission limit time period can be input, accepted and set by displaying an input display of a time period that the user can wait accompanying the screen display prompting the user to input the setting information as described above at step S3 by means of the user interface function unit 363. Alternatively, the transmission limit time period may be set at different timing, or fixedly set.

0084When the storing time exceeds the transmission limit time period (when Yes at step S10), the transmission request determining unit 36 directs the uplink scheduling request processor 37 to transmit an uplink SI, whereby the uplink SI is transmitted to the BTS 1 via the uplink scheduling request processor 37, the E-DCH coding processor 38, the E-DCH modulation processor 39 and the transmitter 40 (Step S11).

0085Namely, the transmission request determining unit 36 (timer function unit 362) has functions as both a wait time monitoring unit which monitors a wait time when the uplink transmission request is waited, and a wait time determining unit which determines whether the wait time monitored by the wait time monitoring unit exceeds a predetermined time period (transmission limit time period). When the wait time determining unit determines that the wait time exceeds the transmission limit time period, the transmission request determining unit 36 controls so that the transmitting means 37 through 40 transmit the uplink transmission request.

0086When the storing time does not exceed the transmission limit time period (when No at step S10), the transmission request determining unit 36 compares the CQI report value calculated by the CQI report value calculator 25 with the CQI threshold value, and determines whether the calculated CQI report value is not less than the CQI threshold value (step S12). The CQI report value to be compared may be an averaged value by an averaging process function unit 341 (steps S12a and S12b).

0087When the calculated CQI report value is below the CQI threshold value, as a result, the transmission request determining unit 36 continuously monitors whether the transmission limit time period has elapsed or not (No route at step S12). When the CQI report value is not less than the CQI threshold value (when Yes at step S12), the uplink transmission electric power monitoring function unit 361 determines whether the current transmission electric power value for the uplink DPDCH is equal to a predetermined transmission electric power threshold value (for example, the maximum electric power value) (step S13).

0088When the current transmission electric power value of the uplink DPDCH is equal to the transmission electric power threshold value (the maximum electric power value) (when Yes at step S13), the transmission request determining unit 36 continuously monitors whether the transmission limit time period has elapsed or not. When not (when No at step S13), the transmission request determining unit 36 directs the uplink scheduling request processor 37 to transmit an uplink SI, whereby the uplink SI is transmitted to the BTS 1 via the uplink scheduling request processor 37, the E-DCH coding processor 38, the E-DCH modulation processor 39 and the transmitter 40 (step S14).

0089Namely, the uplink transmission electric power monitoring function unit 361 has functions as both a transmission electric power value monitoring unit which monitors the current uplink transmission electric power value, and a transmission electric power determining unit which determines whether a result of the monitoring by the transmission electric power value monitoring unit is below a predetermined transmission electric power threshold value or not. The uplink transmission electric power monitoring unit 361 controls the transmitting means 37 through 40 so that the transmission request is transmitted when the transmission electric power determining unit determines that a result of the monitoring is below the transmission electric power threshold value, or transmission of the transmission request is waited when the result of the monitoring is not less than the transmission electric power threshold value.

0090According to this embodiment, in HUSPA, when the UE 2 has uplink transmission data, the UE 2 estimates reception environments at the BTS 1 at the time of uplink (E-DCH) transmission. When the UE 2 determines that the reception environments at the BTS 1 are poor, the UE 2 stores the uplink transmission data in the memory 35 to wait transmission of an uplink SI. When the UE 2 estimates the reception environments of the BTS 1 are good, the UE 2 transmits the uplink SI. This contributes to hold down the transmission electric power of the UE 2, obtain an expected throughput, prevent interference with other radio communication equipments.

0091In the embodiment described above, it becomes possible to monitor the transmission electric power of the uplink (DPDCH) by providing the uplink transmission electric power monitoring function unit 361 to determine whether to transmit the uplink transmission request according to a result of the monitoring, which contributes to decrease the power consumption of the UE 2.

0092By providing the timer function unit 362, it becomes possible to monitor the storing time of the uplink transmission data stored in the memory 35, and determine to transmit the uplink transmission request when the storing time exceeds a predetermined time period (transmission limit time period). Accordingly, it is possible to avoid a case where the uplink transmission request is not transmitted indefinitely, thus the transmission is not initiated.

0093By providing the averaging process function unit 341, the CQIs obtained for a certain period of time are averaged and used as a base of the determination reference. This is helpful to determine transmission of the uplink transmission request on the basis af a CQI value stable in respect to time, whereby the UE 2 can initiate and realize an uplink communication in stable communication environments.

0094By providing the user interface function unit 363, it becomes possible to accept a determination condition (for example, whether transmission of the uplink transmission request can be waited or not, the transmission limit time period or the like) relating to the uplink transmission request from the user of the UE 2, and add it as an element of the determination reference. Whereby, it becomes possible to appropriately change transmission timing of the uplink transmission request according to convenience (will) of the user, which improves utility for the user.

0095By providing the battery monitoring function unit 364, it becomes possible to monitor a battery remaining quantity of the UE 2. Therefore, the smaller the battery remaining quantity, the harder the uplink transmission request is transmitted. This makes it possible to further decrease the power consumption of the UE 2.

0096In the above embodiment, performed are all the determinations on whether the data is data whose transmission can be waited (step S3), whether the battery remaining quantity is small (step S8), whether the storing time of uplink transmission data exceeds the transmission limit time period (step S10) and whether the transmission electric power value of uplink DPDCH is below the threshold value (step S13). However, any one or a plurality of them can be omitted.

0097According to the present invention, the radio terminal controls transmission timing of a transmission request so as to wait transmission of the transmission request of an uplink signal when it is determined that reception environments at the base station are poor, or transmit the transmission request when the reception environments at the base station are good, as described above in detail. Whereby, it is possible to hold down the transmission electric power of the radio terminal, obtain an expected throughput, and reduce interference with other radio communication equipments. Thus, this invention is very useful in the radio communication

technical field.

0098As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiments are therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.