Code sequence transmission method, wireless communication system, transmitter, and receiver

A code sequence transmission method capable of improving system throughput and user throughput by improving power utilization efficiencies of a control channel and a data channel including a plurality of signals having different required qualities is provided. In a mobile station, a bit sequence of a TFCI is transmitted within one frame a plurality of times repeatedly, the bit sequence of each TFCI is multiplied by one bit of a bit sequence of an SI, a multiplication result is transmitted. It is thereby possible to transmit both the TFCI and the SI without providing a signal field of the SI in each frame.

TECHNICAL FIELD

The present invention relates to a code sequence transmission method, a wireless communication system, a transmitter, and a receiver. More specifically, the present invention relates to a code sequence transmission method, a wireless communication system, a transmitter, and a receiver using an EUDCH (Enhanced Uplink Data Channel) that is a channel based on high-speed packet transmission on an uplink according to W-CDMA (Wideband-Code Division Multiple Access).

BACKGROUND ART

According to a technique using the EUDCH that is a high-speed packet transmission channel on an uplink according to the W-CDMA, data is transmitted from a mobile station by configuring a control channel and a data channel and multiplexing codes (see, for example, Non-Patent Document 1). It is, therefore, possible to configure a power on the control channel and that on the data channel independently of each other.

However, a maximum transmission power of the mobile station is limited and data decoding cannot be performed unless a control signal is accurately received. For this reason, the mobile station allocates a necessary power first to the control channel so as to transmit the control channel with a required quality. The mobile station then calculates a remaining power, decides a transmission rate at which a power is equal to or lower than the remaining power as a transmission rate on the data channel, and transmits the control channel and the data channel. Accordingly, if the power used on the control channel is lower, the power that can be used on the data channel is increased, making it possible to select a higher transmission rate.

Meanwhile, the control channel according to the EUDCH includes a plurality of pieces of control information different in required quality. If a transport format (TF) indicating information on a transmission form (e.g., a block size) of data transmitted on the data channel and a scheduling information (SI) necessary for a base station to perform scheduling are transmitted on the control channel, and the base station erroneously receives the TF, the data cannot be decoded. Due to this, an error rate required for the TF is normally set more strictly than that required for the SI.

FIG. 10is an explanatory view of one example of a control signal transmission method according to a conventional art. As stated, on a control channel shown inFIG. 10, a transmission power in a signal field of the TF (TFCI) is configured higher than that in a signal field of the SI, and the TF is transmitted so that a power per bit of the TF is higher. By doing so, even if different required qualities are set for the respective control signals, the control signals can be transmitted on the same channel while satisfying the respective required qualities.

Moreover, transmission of a control signal (TXI: Transmission Indicator) for efficiently using hardware resources of a mobile station is considered (see, for example, Non-Patent Document 2).FIG. 11is an explanatory view of another example of the control signal transmission method according to the conventional art. Referring toFIG. 11, the TXI is a control signal which is used only during soft handover and the transmission of the TXI is stopped in regions other than soft handover regions.Non-Patent Document 1: TR25.808v1.0.0 (2004-12n) 3rd Generation Partnership Project: Technical Specification Group Radio Access Network; FDD Enhanced Uplink; Physical Layer Aspects (Release 6)Non-Patent Document 2: 3GPP RAN WGI #38bis Meeting R1-041066, Sep. 20-25, 2004, “Uplink Control Channel Design for Enhanced Uplink”, MotorolaPatent Document 1: JP-A-2003-229835Patent Document 2: JP-A-8-316967

DISCLOSURE OF THE INVENTION

However, the conventional art has the following problems. As already stated, according to the EUDCH, the required power on the control channel is secured and data channel is transmitted at the remaining power. The power that can be used on the data channel is updated per unit transmission time and should be kept constant within the unit transmission time. Therefore, as shown inFIG. 10, it is necessary to secure the highest required power within the unit transmission time for the control channel. As a result, if a plurality of control signals (TFCI and SI in the example ofFIG. 10) different in required power are transmitted, a remainder of the power is generated while the control signal (SI) at a low required power is transmitted. However, this power cannot be used for data transmission.

Furthermore, the TXI stated above or the like is the control signal necessary only during the soft handover, and the power secured for the control channel is not at all used in a signal field of the TXI in the regions other than the soft handover regions (seeFIG. 11). However, for the same reason as that stated above, this remaining power cannot be used on the data channel.

Generally, a system is designed so that the regions other than the soft handover regions occupy about 60 percent of an entire area. If it is assumed that mobile stations are uniformly distributed, the power which cannot be used is generated in 60 percent of the mobile stations. If the power that cannot be used for the data transmission is generated, then utilization efficiency for using resources of each mobile station is deteriorated, and an average transmission rate on the data channel is reduced. As a result, system throughput and user throughput are deteriorated.

As for the TXI, it may be considered to change a format of the signal field of the TXI within the unit transmission time and to provide no signal field for the TXI in the regions other than the soft handover regions. However, to change the format of the signal field, it is unfavorably necessary to take steps to do so in the base station and each of the mobile stations, and to increase the number of wireless layers and the number of control signals in the network.

It is, therefore, an object of the present invention to provide a code sequence transmission method, a wireless communication system, a transmitter, and a receiver that can solve the above-stated problems, that can improve power utilization efficiency on a control channel and a data channel including a plurality of signals having different required qualities, and that can thereby improve system throughput and user throughput.

To solve the problems, a code sequence transmission method according to the present invention is characterized by comprising steps of: causing a transmitter and a receiver to configure a first channel; deciding a first code sequence and a second code sequence transmitted by the transmitter within a unit transmission time constituted by a plurality of sub-transmission times from a set of first and second code sequences including a plurality of code sequences; causing the transmitter to calculate the first code sequence and each code of the second code sequence within each of the sub-transmission times that constitute the unit transmission time, and to transmit a calculation result; and causing the receiver to determine the first code sequence and the second code sequence received on the first channel from the set of the first and second code sequences.

Moreover, a wireless communication system according to the present invention is characterized by comprising: means for causing a transmitter and a receiver to configure a first channel; means for deciding a first code sequence and a second code sequence transmitted by the transmitter within a unit transmission time constituted by a plurality of sub-transmission times from a set of first and second code sequences including a plurality of code sequences; means for causing the transmitter to calculate the first code sequence and each code of the second code sequence within each of the sub-transmission times that constitute the unit transmission time, and to transmit a calculation result; and means for causing the receiver to determine the first code sequence and the second code sequence received on the first channel from the set of the first and second code sequences.

A transmitter according to the present invention is characterized by comprising: means for configuring, together with a receiver, a first channel; means for deciding a first code sequence and a second code sequence transmitted within a unit transmission time constituted by a plurality of sub-transmission times from a set of first and second code sequences including a plurality of code sequences; means for calculating the first code sequence and each code of the second code sequence within each of the sub-transmission times that constitute the unit transmission time, and for transmitting a calculation result.

A receiver according to the present invention is a receiver in a wireless communication system, the wireless communication system comprising: means for causing a transmitter and the receiver to set a first channel; means for deciding a first code sequence and a second code sequence transmitted by the transmitter within a unit transmission time constituted by a plurality of sub-transmission times from a set of first and second code sequences including a plurality of code sequences; and means for causing the transmitter to calculate the first code sequence and each code of the second code sequence within each of the sub-transmission times that constitute the unit transmission time, and to transmit a calculation result, the receiver characterized by comprising means for determining the first code sequence and the second code sequence received on the first channel from the set of the first and second code sequences.

According to the present invention, the transmitter calculates the first code sequence and the second code sequence and transmits the calculation result to the receiver.

EFFECT OF THE INVENTION

According to the present invention constituted as stated above, it is possible to improve the power utilization efficiency on the control channel and the data channel including a plurality of signals having different required qualities, and improve the system throughput and user throughput.

Namely, according to a first embodiment of the present invention, a bit sequence of a TFCI is transmitted repeatedly within one frame a plurality of times, a bit sequence of each TFCI is multiplied by one bit of a bit sequence of an SI, and a multiplication result is transmitted. It is thereby possible to transmit both the TFCI and the SCI without providing the signal field for the SI in the frame.

By doing so, even if the TFCI and SI differ in required quality, it is possible to satisfy the required qualities of both the TFCI and the SI and make a transmission power on each frame of an E-DPCCH (E-DCH Dedicated Physical Control channel) uniform.

Accordingly, the power utilization efficiency can be improved, the average power allocated to the E-DPDCH can be increased, and the system throughput and the user throughput can be improved.

Moreover, according to a second embodiment of the present invention, even if a control signal used only during soft handover is present, it is unnecessary to provide a signal field for the control signal. Therefore, even if the same frame format is always used, a deterioration in power utilization efficiency can be avoided and the throughput can be improved. Furthermore, since it is unnecessary to change the frame format according to whether the region is a soft handover region or the other region, procedures accompanying the change of the frame format can be reduced. In addition, control signal traffic on a wireless layer and in the network can be reduced.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described hereinafter with reference to the accompanying drawings. In the embodiments, an EUDCH according to W-CDMA will be described by way of example.

First Embodiment

FIG. 1is a block diagram of a wireless communication system according to a first embodiment of the present invention. InFIG. 1, the wireless communication system according to the first embodiment of the present invention includes a base station101provided in a cell1, and mobile stations111and112connected to the base station101. The following channels are configured between this base station101and the respective mobile stations111and112, and data is transmitted on uplink (in a direction from the mobile stations111and112to the base station101).

Referring toFIG. 1, E-DPCCH is an uplink channel for transmitting a control signal on an EUDCH, and E-DPDCH (E-DCH Dedicated Physical Data Channel) is an uplink channel for transmitting data on the EUDCH. In addition, E-RGCH (EDCH Relative Grant Channel) is a channel on downlink (in a direction from the base station101to the mobile stations111and112) for transmitting the control signal on the EUDCH, and DPCH (Dedicated Physical Channel) is a channel on both uplink and downlink for transmitting a transmission power control signal.

A unit transmission time (one frame) of each of these channels is, for example, 10 ms, and one frame includes, for example, 15 slots. Each of the base station101and the mobile stations111and112transmits a pilot signal and a transmission power control signal (TCP) in slots on the DPCH. A closed loop transmission power control is exercised so that the DPCHs on the uplink and the downlink attain predetermined target qualities, respectively.

Moreover, the base station101schedules the mobile station111or112that transmits data on the EUDCH in frames so that a ratio of a total reception power to a noise power (“noise rise”) is equal to or lower than a predetermined target value. The base station101notifies each of the mobile stations111and112of a maximum transmission rate on the E-DPDCH which each of the mobile stations111and112is granted to use, on the E-RGCH.

Each of the mobile stations111and112and the base station101is notified, in advance, of a set of transport formats (TFs) that can be used on the E-DPDCH. Each of the mobile stations111and112selects a TF used for transmission on each frame.

FIG. 2is an explanatory view of bit sequences of TFs employed in the first embodiment. In this embodiment, as shown inFIG. 2, the transport format set includes, for example, three types of TFs, e.g., TF1(TFCI1) to TF3(TFCI3). Namely, a transmission rate of the TFCI1is 0 kbps and a bit sequence of the TFCI1is represented by, for example, “010101”. A transmission rate of the TFCI2is 32 kbps and a bit sequence of the TFCI2is represented by, for example, “001100”. A transmission rate of the TFCI3is 64 kbps and a bit sequence of the TFCI3is represented by, for example, “101101”.

FIG. 3is an explanatory view of an example of bit sequences of SIs employed in the first embodiment of the present invention. In this embodiment, as shown inFIG. 3, the transport format set includes three types of SIs, e.g., SI1to SI3. Namely, the SI1indicates control (maximum transmission rate) UP and a bit sequence of the SI1is represented by, for example “11111”. The SI2indicates control (maximum transmission rate) DOWN and a bit sequence of the SI2is represented by, for example, “00000”. The SI3indicates control (maximum transmission rate) Keep and a bit sequence of the SI3is represented by, for example, “01010”.

Each of the mobile stations111and112calculates a remaining power P_remain [mW] by subtracting powers P_dpch [mW] and P_edpech [mW] required on the DPCH(UL) (uplink DPCH) and E-DPCCH, respectively from a maximum transmission power P_max [mW]. In addition, each of the mobile stations111and112selects a TF in which the required power is equal to or lower than P_remain and in which the transmission rate is the highest among TFs in which the required power is equal to or lower than P_remain and in which the transmission rate is equal to or lower than the maximum transmission rate notified by the base station101on the E-RGCH. At this time, the required power for the E-DPDCH is assumed to be a power obtained by multiplying the power on the DPCH by a true value of a power offset ΔTFx [dB] (where x=1, 2, 3) specified for each TF.

Each of the mobile stations111and112transmits two control signals, i.e., a TFCI and an SI on the E-DPCCH. The TFCI is assumed to be configured so that one block includes I N-bit bit sequences Xi=(xi,1, xi,2, . . . , xi,N,) (where N is a positive integer and i=1, . . . , I). In addition, the SI is assumed to be configured so that one block includes J M-bit bit sequences Yj=(yj,1, yj,2, . . . , yj,M,) (where M is a positive integer and j=1, . . . J). In this embodiment, as shown inFIGS. 2 and 3, N, I, M, and J are set to, for example, N=6, I=3, M=5, and J=3.

The TFCI is a signal for notifying the base station101of the TF used on the E-DPDCH and selected by each of the mobile stations111and112. The SI is a signal for causing each of the mobile stations111and112to request the maximum transmission rate to be increased or reduced. The SI is decided under the following conditions based on a data amount D, a present maximum transmission rate Rmax, and a target transmission delay range from T−ΔT to T+ΔT that are stored in a buffer.

(1) At D/Rmax<T−ΔT, the SI indicates Down (request to reduce the maximum transmission rate); (2) At T−ΔT<D/Rmax<T+ΔT, the SI indicates Keep (request to keep the present maximum transmission rate); and (3) At T+ΔT<D/Rmax, the SI indicates Up (request to increase the maximum transmission rate).

Each of the mobile stations111and112requests the maximum transmission rate to be changed so as to be able to transmit data within the target delay range using the above-decided SI signal.

It is assumed that a required power on the E-DPCCH is a power obtained by multiplying the power P_dpch [mW] on the DPCH by a true value of a power offset Δedpcch [dB]. The value of the power offset Δepdcch is decided according to whether one of or both the SI and the TFCI are transmitted. If the mobile station111or112does not transmit the TFCI, a power offset Δedpcch1is used. If the mobile station111or112transmits the TFCI, a power offset Δedpcch2is used. The relationship between the values of power offset is Δedpcch1<Δedpcch2. This is because an error rate requested for the TFCI is stricter than that for the SI. To transmit the TFCI, the power offset is configured higher than that for transmitting the SI, thereby satisfying the error rate requested for the TFCI. Conversely, if the TFCI is not transmitted, the required power on the E-DPCCH can be configured low.

FIG. 4is an explanatory view of one example of a method for the E-DPCCH transmission. By way of example, a frame of the E-DPCCH is divided into five subframes, the TFCI is transmitted once per subframe, and five TFCIs are transmitted per frame. On the other hand, the SI is transmitted one bit by one bit per subframe, and one SI is transmitted per frame. If so, an exclusive OR (XOR) is performed between each of six bits of the TFCI and one bit of the SI.

Namely, the bit sequence of each TFCI transmitted repeatedly are masked by the bit sequence of the SI, thereby transmitting information on both the TFCI and the SI on one frame. It is, therefore, unnecessary to provide a field for transmitting information bits of the SI in a frame, and the power can be uniformly set in each frame. Due to is, the power utilization efficiency can be improved without non-uniformity of the power in the frame resulting from the difference in required power between the TFCI and the SI as described in the “Best Mode for Carrying out the Invention” Part. Therefore, it is possible to increase the power that can be used on the E-DPDCH and improve the throughput.

The method for the E-DPCCH transmission will be described specifically, assuming that the bit sequence of the TFCI is Xi=(xi,1, xi,2, . . . , xi,6,) (where i=1, 2, 3 and i indicates a TFCI number) and that the bit sequence of the SI is Yi=(yj,1, yj,2, . . . , yj,6,) (where j=1, 2, 3 and j indicates an SI number).

For instance, if the mobile station decides that a TFCI3(where i=3) and an SI3(where j=3) are bit sequences to be transmitted, a bit sequence Z3,3=(x3,1·y3,m, x3,2·y3,m, . . . , x3,6·y3,m) obtained by multiplying each bit of X3=(x3,1, x3,2, . . . , x3,6) by an m-th bit y3,m of Y3on an m-th frame of the E-DPCCH. The mobile station transmits these bit sequences over five frames for m=1 to 5.

FIG. 5is a flowchart of an operation related to the E-DPCCH transmission on the mobile station employed in the first embodiment of the present invention. Each of the mobile stations111and112decides which request signal SI among the SI1(UP), the SI2(Down), and the SI3(Keep) is used to request the transmission rate to be increased or reduced based on the data amount in the buffer and the present maximum transmission rate (step401).

If no data is present in the buffer or the maximum transmission rate is zero, the mobile station111or112does not transmit data (step402, No). Accordingly, the power offset on the E-DPCCH is configured to the Δedpcch1(step403). Otherwise, the mobile station111or112transmits data (step402, Yes), and the power offset on the E-DPCCH is configured to the Δedpcch2(step404).

Thereafter, the mobile station111or112selects a TF used to transmit the data from among TFs in which the power is equal to or lower than the power that can be used on the E-DPDCH and in which the transmission rate is equal to or lower than the maximum transmission rate (step405), and sets the subframe number m to 1 (m=1) (step406). In addition, the mobile station111or112performs an exclusive OR (XOR) on the bit sequence of the TFCI indicating the selected TF and the m-th bit of the bit sequence of the SI (step407), and transmits a calculation result to the base station101on the m-th subframe of the E-DPCCH (step408)

Subsequently, the number m is compared with the number M of subframes per frame (where M=5 in this embodiment). If the m is equal to or smaller than the M (step410, No), then the processing returns to the step407, and the calculation XOR is repeatedly executed until the m becomes greater than the M. When the m becomes greater than the M (step410, Yes), the mobile station111or112finishes transmitting the data corresponding to one frame of the E-DPCCH.

FIG. 6is a block diagram of one example of the mobile station employed in the first embodiment of the present invention. The mobile station111or112according to the present invention includes a reception processing unit501, a signal separating unit502, a received signal quality measuring unit503, a TPC signal generating unit504, a power calculating unit505, a to-be-transmitted data selecting unit506, a buffer507, an SI signal generating unit508, a TFCI signal generating unit509, a signal combining unit510, and a transmission processing unit511. The reception processing unit501performs a reception processing such as despreading on a signal. The signal separating unit502separates the signal received by the reception processing unit501into a TPC signal, a maximum transmission rate signal, and a pilot signal. The received signal quality measuring unit503measures a received signal quality of the pilot signal obtained by separating the received signal. The TPC signal generating unit504generates a transmission power control signal from the received signal quality of the pilot signal. The power calculating unit505calculates a power on the E-DPDCH. The to-be-transmitted data selecting unit506selects to-be-transmitted data. The buffer507stores data on the E-DPDCH. The SI signal generating unit508generates the SI signal. The TFCI signal generating unit509generates the TPCI signal. The signal combining unit510combines the SI signal with the TFCI signal. The transmission processing unit511performs a transmission processing on the combined signal.

The power calculating unit505decides powers used on the DPCH and E-DPCCH, respectively based on information from the transmission processing unit511and on whether or not data is present in the buffer507. In addition, the power calculating unit505notifies the to-be-transmitted data selecting unit506of a power obtained by subtracting the powers used on the DPCH and that used on the E-DPCCH from the maximum power as the power than can be used on the E-DPDCH.

The to-be-transmitted data selecting unit506selects a TF in which the power is equal to or lower than the power that can be used on the E-DPDCH and the transmission rate is the highest among the TFs in which the transmission rates are equal to or lower than the maximum transmission rate notified by the base station101, and notifies the buffer507of the selected TF. The buffer507transmits a data block at a block size specified by the notified TF to the transmission processing unit511.

Moreover, the selected TF is transmitted to the TFCI signal generating unit5099and a bit sequence corresponding to the selected TF is transmitted to the signal combining unit510. Information on the data amount in the buffer507and the maximum transmission rate is transmitted to the SI signal generating unit508. The SI signal generating unit508decides the SI for requesting the transmission rate to be increased or reduced, and transmits a corresponding bit sequence to the signal combining unit510.

The signal generating unit510transmits five bit sequences obtained by performing exclusive ORs on the six bits of the TFCI and each bit of the SI to the transmission processing unit511. The transmission processing unit511transmits one bit sequence per subframe.

FIG. 7is a block diagram of one example of the base station employed in the first embodiment of the present invention. The base station101according to the present invention includes a reception processing unit601, a signal separating unit602, a received signal quality measuring unit603, a TPC signal generating unit604, a determining unit605, a decoding unit606, a scheduler607, and a transmission processing unit608. The reception processing unit601performs a reception processing such as channel estimation and despreading on a signal. The signal separating unit602separates the signal received by the reception processing unit601into an E-DPCCH signal, an E-DPDCH signal, and a pilot signal. The received signal quality measuring unit603measures a received signal quality of the pilot signal obtained by dividing the received signal. The TCP signal generating unit604generates a transmission power control signal based on the received signal quality of the pilot signal. The determining unit605determines the E-DPCCH signal. The decoding unit606decodes E-DPDCH data. The scheduler607schedules the mobile station111or112for causing the mobile station111or112to transmit data on the E-DPDCH. The transmission processing unit608performs a spreading processing and the like on the signal.

The determining unit605determines a combination of the TFCI and the SI received as a signal R=(r1, r2, . . . , r30) received on the E-DPCCH based on the received signal R, a bit sequence set Xi=(xi, 1, xi, 2, . . . , xi, 6) (where i=1, 2, and 3, and i indicates a TFCI number) of the TFCIs and a bit sequence set Yj=(yj, 1, yj, 2, . . . , yj, 5) (where j=1, 2, 3, and j indicates an SI number) of the SIs. If a channel estimated value transmitted from the reception processing unit601is assumed as h, the determining unit605calculates a distance Zij between each bit sequence and the received signal relative to the combination of the TFCI number i and the SI number j as represented by the following equation.

The determining unit605calculates distances Zij relative to all combinations of the i and the j, respectively, as shown below, and determines the TFCI and the SI corresponding to the combination that indicates the smallest distance as the TFCI and the SI received as the received signal R.

Information on the TFCI thus determined is transmitted to the decoding unit606. The decoding unit606decodes the received signal on the E-DPDCH at the block size specified for the TFCI. In addition, information on the SI determined by the determining unit605is transmitted to the scheduler607. The scheduler607schedules the mobile stations111and112based on the SI transmitted from the mobile stations111and112, decides the maximum transmission rate, and transmits the decided maximum transmission rate to the transmission processing unit608.

In this manner, according to the first embodiment, the bit sequence of the TFC is repeatedly transmitted on each frame a plurality of times, the bit sequence of each TFCI is multiplied by one bit of the bit sequence of the SI, and the resultant bit sequence is transmitted. It is thereby possible to transmit both the TFCI and the SI without providing the signal field for the SI in each frame.

By so configuring, even if the TFCI and the SI differ in required quality, it is possible to satisfy the required qualities of both the TFCI and the SI and make the transmission power on each frame of the E-DPCCH uniform. Therefore, the power utilization efficiency can be improved, the average power allocated to the E-DPDCH can be increased, and the system throughput and the user throughput can be improved.

Second Embodiment

FIG. 8is a block diagram of a wireless communication system according to a second embodiment of the present invention. Referring toFIG. 8, the wireless communication system according to the second embodiment of the present invention includes a base station1001provided in the cell1, mobile stations1011and1012connected to the base station1001, a base station1002provided in a cell2, and the mobile stations1012connected to the base station1002. Namely, the mobile station1012present near a boundary between the cells1and2establish radio links to the two base stations1001and1002, respectively. Only the base station1001out of the base stations1001and1002(Active Set base stations, “AS base stations”) for which the respective radio links are established performs scheduling, and the other AS base station1002does not perform scheduling. Since channels set among the base stations1001and1002and the mobile stations1011and1012are the same as those according to the first embodiment, they will not be described herein.

The mobile stations1011and1012according to the second embodiment differ from the mobile stations111and112according to the first embodiment in the following respects. If the mobile station (e.g., the mobile station1012) according to the second embodiment establish the radio links to the base stations1001and1002, respectively, the base station transmits not only the TFCI but also a control signal TXI (transmission index) on the E-DPCCH. Neither the mobile station1011nor1012according to the second embodiment transmit the SI which the mobile stations111and112according to the second embodiment transmit.

FIG. 9is an explanatory view of bit sequences of TXIs employed in the second embodiment of the present invention. The TXI is a signal for notifying the base station whether to transmit data on a next frame of the E-DPDCH, and each uses the bit sequences shown inFIG. 9. That is, a TXI1indicates that data is transmitted and the bit sequence of the TXI1is represented by, for example, “11111”. A TX2indicates that no data is transmitted and the bit sequence of the TXI2is represented by, for example, “00000”.

If each As base station receives the TXI and determines that data is transmitted on the next frame, the AS base station allocates a despreader to this mobile station. If the AS base station determines that no data is transmitted from the mobile station on the next frame, the AS base station does not allocate the despreader to the mobile station. By doing so, even the base station (which is the base station1002according to this embodiment) that does not perform scheduling, i.e., the base station that cannot transmit a command to permit or prohibit the mobile station to transmit or receive data can allocate the despreader only to the mobile station that transmits data. In addition, a hardware scale of the base station relative to a required received signal capacity can be reduced.

Each mobile station according to the second embodiment calculates a bit sequence of the TFCI using not the SI signal but the TXI signal, and transmits the TFCI and the TXI on the E-DPCCH.

The second embodiment exhibits the following effects besides those described in the first embodiment.

Namely, the TXI is the control signal transmitted only if each mobile station establish the radio links to the respective base stations. By using this TXI, it is unnecessary to provide the signal field for the TXI. Accordingly, even if the frame format is the same between the instance in which each mobile station establishes the rank links to the respective base stations and the instance in which each mobile station does not establish the radio links to the respective base stations, it is possible to prevent deterioration in power utilization efficiency, and improve the throughput. Besides, it is unnecessary to change the format according to whether or not the soft handover is performed. It is, therefore, possible to eliminate procedures accompanying the change of the frame format, and reduce an amount of the control signal on the wireless layer and in the network.

INDUSTRIAL APPLICABILITY

The present invention can be applied to the communication system in which each mobile station is replaced with a transmitter and each base station is replaced with a receiver, particularly to the communication system other than a cellular system. Furthermore, the present invention can be applied to not only the control over the uplink but also a control over the downlink.