Communication Control Method, Radio Communication System, Base Station, and Mobile Station

Abstract

In a radio communication system that performs HARQ (Hybrid Automatic Repeat request), a mobile station returns the HARQ process state of the mobile station to the free state by the reception of ACK. In this state, the mobile station, upon receiving from the scheduling base station an SA (scheduling assignment) for assigning resources for retransmission, transmits a transmission process state notification reporting that the mobile station is in the free state when the mobile station does not have new data to be transmitted. The base station therefore recognizes that the mobile station is in the free state and returns the HARQ process state of the base station to the free state and halts the assignment of resources to the mobile station.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view of HARQ process states in a mobile station;

FIG. 2 is an explanatory view of HARQ) process states in a base station;

FIG. 3 is a timing chart showing the timing of transmission of HARQ in synchronous transmission;

FIG. 4 is a timing chart showing the timing of transmission of HARQ in asynchronous transmission;

FIG. 5 shows signals exchanged between a base station and a mobile station;

FIG. 6 is a sequence chart showing the exchange of signals between a base station and a mobile station;

FIG. 7 is a sequence chart showing the exchange of signals between a base station and a mobile station when in the SHO (soft hand-over) state;

FIG. 8 is a sequence chart showing processing when NACK is erroneously received as ACK;

FIG. 9 is a sequence chart showing processing when ACK is erroneously received as NACK;

FIG. 10 shows the signals exchanged between a base station and a mobile station when time scheduling is used;

FIG. 11 is a sequence chart showing the exchange of signals between a base station and a mobile station when time scheduling is used;

FIG. 12 is a sequence chart for explaining problems that occur in the SHQ state;

FIG. 13 is a view for explaining the problems that occur when NACK is mistaken for ACK;

FIG. 14 is a view for explaining the problems that occur when ACK is mistaken for NACK;

FIG. 15 shows an example of the configuration of a cellular system in which the present invention is applied;

FIG. 16 is a sequence chart showing the exchange of signals between a base station and a mobile station in the SHO state in the first embodiment;

FIG. 17 is a flow chart showing processing in the mobile station in the first embodiment;

FIG. 18 is a flow chart showing processing in the base station in the first embodiment;

FIG. 19 is a block diagram showing the configuration of the base station in the first embodiment;

FIG. 20 is a block diagram showing the configuration of the mobile station in the first embodiment;

FIG. 21 is a sequence chart showing the exchange of signals between a base station and a mobile station in the SHO state in the second embodiment;

FIG. 22 is a flow chart showing the processing in the mobile station in the second embodiment;

FIG. 23 is a flow chart showing processing in the base station in the second embodiment;

FIG. 24 is a block diagram showing the configuration of the base station in the second embodiment;

FIG. 25 is a block diagram showing the configuration of the mobile station in the second embodiment; and

FIG. 26 is a view for explaining an example of the transmission of a HARQ process state report in the fourth embodiment.

EXPLANATION OF REFERENCE NUMBERS

801, 1001, 1501, 1601 Reception processor
802, 1002, 1502, 1602 Control signal separator
803, 1503             Decoding processor
804, 1005, 1504, 1605 Buffer
805, 1505             Error detector
806, 1003, 1506, 1603 HARQ controller
807, 1507             Scheduler
808, 1006, 1508, 1606 Encoding processor
809, 1008, 1509, 1608 Control signal combiner
810, 1009, 1510, 1609 Transmission processor
1004, 1604            TFC selector
1007, 1607            Retransmission buffer
1010                  Retransmission wait counter

BEST MODE FOR CARRYING OUT THE INVENTION

Explanation next regards preferable embodiments of the present invention with reference to the accompanying figures. In the following explanation, the present invention will be described using a case in which the communication control method of the present invention is applied to EUDCH in WCDMA.

FIG. 15 shows an example of the configuration of a cellular system in which the communication control method of the present invention is applied. The first to sixth embodiments described hereinbelow are described as cases in which the communication control methods of the embodiments are applied to the cellular system shown in FIG. 15.

In the case shown in the figure, two base stations (BTS) 411 and 412 are provided, base stations 411 and 412 corresponding to cells 401 and 402, respectively. An area exists in which cell 401 and cell 402 overlap, and SHO (soft hand-over) between base station 411 and base station 412 is being offered to mobile station (MS) 422 located within this area. Mobile station 421 in cell 401 is connected only to base station 411, mobile station 423 in cell 402 is connected only to base station 412, and mobile stations 421 and 423 perform transmission and reception of E-DPDCH(UL) for transmitting EUDCH data and E-DPCCH(UU/DL) for transmitting control signals. In addition, mobile station 422 is connected to both base stations 411 and 412, and this mobile station is transmitting and receiving E-DPDCH(UL) for transmitting EUDCH data and E-DPCCH(UL/DL) for transmitting control signals. Radio network controller (RNC) 430 connected to base stations 411 and 412 is further provided. Here, the suffix “UL” represents an uplink, and the suffix “DL” represents a downlink.

Radio network controller (RNC) 430 notifies mobile stations and base stations of sets of TFC (Transport Format-Combinations), which are combinations of transmission formats that each mobile station is permitted to use. A TFC set is referred to as “TFCS.” TFC includes parameters such as the transmission time interval (TTI) and the number of information bits that are contained in TTI. The transmission rate of EUDCH changes according to the TFC, the higher the transmission rate the higher the noise rise applied to the base station. In this way, a base station, by controlling the maximum TFC that a mobile station is permitted to use, controls fluctuation of the noise rise in the base station. The control information for this control is transmitted and received between the base station and the mobile station by using E-DPCCH(UL/DL).

In addition, HARQ is used in this cellular system. Mobile stations 421. 422 and 423 use E-DPDCH to transmit data blocks at prescribed transmission intervals. Base stations 411 and 412 determine from the CRC of received data blocks whether the data blocks have been correctly decoded or not, and then transmit on the E-DPCCH of the downlink either ACK, which is a delivery confirmation signal indicating that correct reception was possible, or NACK, which is a delivery confirmation signal indicating a reception error. Mobile station 422, having set EUDCH circuits with two base stations, receives ACK/NACK signals from both base stations. When mobile station 4Z2 receives ACK from either one of the base stations, mobile station 422 views that data block as having been correctly received and discards the data, and mobile station 422 performs retransmission only when NACK is received from both base station.

First Embodiment

Explanation next regards the communication control method according to the first embodiment.

In the first embodiment, the use of time/transmission rate scheduling and the use of synchronous transmission for HARQ will be assumed. It is further assumed that, regarding retransmissions, the base station will command, i.e., a base station-controlled retransmission method will be used.

In the present embodiment, a configuration is adopted in which TFCI is used to enable communication of the HARQ process states of mobile stations. TFCI are bit sequences indicating the TFC that prescribe the transmission data format, and of these bit sequences, two will be defined as the free state notification and the retransmission state notification. The use of five-bit TFCI is here assumed as shown in the following table. In other words, TFCI0 is defined as the free state and TFCI1 is defined as the retransmission state.

	TABLE 1
	TFCI Classification	Bit Sequence	Definition
	TFCI0	00000	Free state
	TFCI1	11111	Retransmission state
	TFCI2	01010	TFC0
	TFCI3	10101	TFC1
	TFCI4	00100	TFC2

Mobile stations use the HARQ process state notification in the following cases:

(a) when the mobile station receives SA when in the free state, and moreover, there are no data to be-transmitted in the buffer;

(b) when the mobile station receives SA when in the free state and the mobile station has data to be transmitted but does not transmit the data;

(c) when the mobile station is in the retransmission state and SA has been assigned in which the transmission rate is lower than required for retransmission; and

(d) when the mobile station is in the retransmission state and resources have not been assigned for N consecutive transmission timings of the relevant HARQ process after receiving NACK.

When any one of the above-described conditions (a) to (d) is satisfied, the mobile station transmits TFCI that reports the state of the relevant HARQ process and the current NDI at the designated transmission timing. At this point, a base station transmits ACK, or a mobile station receives ACK, and at the time point at which transmission of the data packets is determined to have ended, NDI it increased by “1” to update NDI in preparation for the next new data transmission.

A base station, upon receiving TFCI notifying of the HARQ process state, checks its own HARQ process state, and if there is an inconsistency, either corrects to match the mobile station or notifies the mobile station of the HARQ process state of the base station.

FIG. 16 is a sequence chart showing the exchange of signals between a base station and a mobile station in the SHO state in the first embodiment. The exchange of signals in the prior art that corresponds to the exchange of signals shown in FIG. 16 is shown in the above-described FIG. 12.

When the mobile station transmits SI to the scheduling base station in step S501, the scheduling base station transmits an SA to the mobile station in Step S502, and the mobile station then sets the NDI to NDI=0 and transmits the date block to each of the base stations in accordance with the received SA in Steps S503 and S504. In the case shown here, the mobile station then receives NACK from the scheduling base station in Step S505, and receives ACK from the non-scheduling base station in Step S506. The mobile station has received at least one ACK, and therefore returns the HARQ process of its own station to the free state and increases the NDI by “1.” However, the scheduling base station is in the retransmission state and therefore transmits an SA the mobile station in Step S507 to assign resources for retransmission. If it is assumed that the data to be transmitted are no longer present in the mobile station at this time, the above-described condition (a) is satisfied, and the mobile station therefore transmits NDI=1 and TFCI0 in Step S508 to report that it is in the free state. The scheduling base station thereby recognizes that the mobile station Is in the free state, and further, because the NDI is greater by “1” than the NDI being managed in the scheduling base station, determines that the mobile station does not hold the data that should be transmitted. The scheduling base station then returns the HARQ process of its own station to the free state and terminates assignment of resources to that mobile station. The present embodiment thus enables the resolution of inconsistencies in the HARQ processes between a scheduling base station and a mobile station, and can avoid the pointless assignment of resources.

FIG. 17 is a flow chart showing the flow of processes of a mobile station from the timing of the reception of an SA up to the updating of the HARQ process state in the present embodiment.

The mobile station first determines-whether an SA has been received or notate the SA reception timing as shown in Step S501a, and then proceeds to Step S511a if reception has been possible and to Step S502a if reception was not possible. The processing in the mobile station is next described dividing between a case in which reception was not possible and a case in which reception was possible.

When Reception of the SA was Not Possible at the SA Reception Timing:

When the mobile station is not able to receive the SA at the SA reception timing, the mobile station first determines whether its own mobile station is in the free state or not in Step S502a, If in the free state, the mobile station returns to initial Step S501a while remaining in the free state as shown in Step S503a. If not in the free state in Step S502a, i.e., if in the retransmission state, the, mobile station increases the counter by “1” in Step S504a and then compares the value of the counter with the prescribed maximum number of retransmission waiting N in Step S505a. If the value of the counter does not exceed N, the mobile station returns to the initial Step S501a without changing from the retransmission state as shown in Step S56. If, on the other hand, the value of the counter is greater than N in Step S505a, the mobile station transmits a retransmission state notification and NDI in Step S507a. The mobile station here determines in Step S508a whether ACK has been received at a prescribed ACK/NACK transmission timing. If ACK has been received, this reception indicates that the base station is in the free state, and the mobile station therefore returns its own HARQ process state to the free state and increases the NDI by “1” in Step S509a. On the other hand, if ACK has not been received, i.e., if NACK has been received in Step S508a, this reception means that the base station is still in the retransmission state, and the mobile station therefore resets the counter in Step S510 and proceeds to Step S506a without changing from the retransmission state.

When SA was Received at the SA Reception Timing:

When the mobile station has received an SA at the SA reception timing, the mobile station determines whether its own station is in the free state or not in Sep S511a. If not in the free state, i.e., if in the retransmission state, the mobile station determines in Step S512a whether the assigned transmission rate is adequate for transmission of the retransmission data or not. If the transmission rate is adequate, the mobile station transmits the retransmission data in Step S513a, and if inadequate, the mobile station transmits a retransmission state notification and NDI in Step S514a. The mobile station then determines in Step S515a whether it has received ACK at the prescribed ACK/NACK transmission timing, and if ACK has been received, returns the HARQ process state of its own station to the free state and increases the NDI by “1” in Step S516a and returns to the initial Step S501a. On the other hand, if ACK has not been received, i.e., if NACK has been received in Step S515a, the mobile station remains in the retransmission state and returns to the initial Step S501a as shown in Step S517a. In this way, when the mobile station is in the retransmission state but has not been assigned the resources necessary for retransmission, the mobile station transmits a retransmission state notification whereby the retransmission state of the mobile station can be detected in the base station. The base station then transmits ACK, whereby the mobile station can recognize that the data waiting for retransmission have already been correctly received and can correct its own station to the free state.

Alternatively, when the mobile station is in the free state in Step S511a, the mobile station determines in Step S518a whether there are data to be transmitted, and if there are data to be transmitted, transmits new data in Step S519a and determines in Step S520a whether ACK is received at the prescribed timing. If ACK is received, the mobile station returns the state of its own station to the free state and increases the NDI by “1” in Step S521a and then returns to the initial Step S501a, On the other hand, if ACK is not received in Step S520a, i.e., if NACK is received,-the mobile station sets the state of its own, station to the retransmission state in Step S522a and returns to the initial Step 8501a. If there are no data to be transmitted in Step S518a, the mobile station transmits a free state notification and NDI in Step S523a and returns to the initial Step S501a. In this way, the base station is able to detect that the mobile station is in the free state and can terminate the pointless assignment of resources.

FIG. 18 is a flow chart showing the flow of processing in the base station from the timing of receiving SA up to the updating of the HARQ process state. The flow of processing in this base station is the counterpart of the flow of processing in the mobile station shown in FIG. 17.

The processing of the base station differs according to whether an SA had been transmitted at the SA transmission timing as shown in Step S501b, the process moving to Step S506b if the SA has been transmitted and the process moving to Step S502b if the SA has not been transmitted. The processing at the base station is next explained by dividing between a case in which the SA has not been transmitted and a case in which the SA has been transmitted.

When an SA has Not Been Transmitted:

When the base station has not transmitted an SA the base station determines in Step S502b whether a retransmission state notification has been received or nit, and if a retransmission state notification has been received, next determines in Step S503b whether the state in the base station is the retransmission state or not. If the state is the retransmission state, the base station both transmits NACK to the mobile station and then ends the process with this HARQ process maintained in the retransmission state in Step S504b. If tho state in the base station is the free state in Step S503b, the base station transmits ACK in Step S505b, and then ends the process with the state in the base station remaining in the free state. If a retransmission state notification has .Not been received in Step S502b, the base station ends the process.

When an SA has Been Transmitted:

If the base station has transmitted an SA, the base station determines in Step S506b whether TFCI has been received at the instructed transmission timing, and if TFCI has not been received, increases the transmission power of the SA in Step S507b and returns to Step S501b. These circumstances occur when the mobile station has not received the SA correctly, and by increasing the-power, the SA error rate can be reduced. If reception of TFCI was possible in Step S506b, the base station determines in Step S508b whether the TFCI is a HARQ process state notification or not. If the TFCI is a HARQ process state notification, the base station next determines in Step S509b whether this notification reports the free state, and if the notification reports the free state, in Step S510b, the base station checks the NDI that is reported together with the notification to determine whether the NDI has the same value as the value being managed in the base station. Here, if the reported NDI is different from the NDI managed in the base station, the base station determines in Step S511b that data to be transmitted are not present in the mobile station, assumes the free state, terminates scheduling of this mobile station until there is a new data generation notification, and ends the process. Alternatively, if the NDI in Step S510b are the same, the base station determines in Step S512b that the mobile station is in a state of holding data but unable to transmit, and the base station therefore lowers the priority of this mobile station, assumes the free state, and ends the process. When a free state notification is received in this way, the pointless assignment of resources can be terminated.

If the state is not the free state in Step S509b, i.e., if the received HARQ process state notification is for a retransmission state, the base station checks in Step S513b whether the HARQ process state in the base station is the retransmission state or not. If the state in the base station is the retransmission state, the base station transmits NACK and ends the process with this HARQ process in the retransmission state in Step S514b. Alternatively, if in Step S513b the HARQ process in the base station is not the retransmission state, i.e., if the state is the free state, the base station transmits ACK and ends the process while remaining in the free state in Step S515b. In this way, when the mobile station is in the retransmission state and the base station is in the free state, the base station corrects the HARQ process of the mobile station to the free state by transmitting ACK.

If the received TFCI is not a HARQ state notification in Step S508b, the base station carries out the data block reception process in Step S518b and determines in Step S519b whether correct reception was possible or not. If the data block was correctly received, the base station transmits ACK, assumes the free state, and ends the process in Step S520b. If the base station determines in Step S519b that the data block was not received correctly, the base station transmits NACK, assumes the retransmission state, and ends the process in Step S521b.

By means of the above-described flow, the base station updates the state of each HARQ process and carries out scheduling while taking into consideration of the HARQ process state and the volume of data that have not yet been received that is calculated from the difference between the buffer size reported by each mobile station and the received data size.

FIG. 19 is a block diagram showing the configuration of a base station used in the present embodiment.

The base station is provided with: reception processor 801 for carrying out such processes as the despreading of received signals; control signal separator 802 for separating received signals that have undergone despreading into control signals and data; decoding processor 803 for decoding the separated data; buffer 804 for accumulating data that have been decoded, one or a plurality of buffers 804 being prepared for each mobile station; error detector 805 for detecting errors in the decoded data; HARQ controller 806 provided corresponding to each mobile station for controlling HARQ process states; scheduler 807 for carrying out scheduling for each mobile station; encoding processor 808 for performing an encoding process for downlink data; control signal combiner 809 for combining control signals and downlink data that have been encoded; and transmission processor 810 for carrying out , processing such as a spreading process upon output signals from control signal combiner 809 to produce transmission signals.

In a base station of this configuration, processing such as the despreading of received signals is carried out in reception processor 801, and received signals that have undergone processing in reception processor 801 are then separated into control signals and data in control signal separator 802. Of the control signals that have been separated, SI that includes information for scheduling is sent to scheduler 807 and HARQ process state notifications and NDI are sent to HARQ controller 806. The separated data are decoded in decoding processor 803, and then-accumulated in buffers 804, one or a plurality of buffers being provided for each mobile station. During the decoding process in decoding processor 803, error detector 805 carries out error detection for the decoded data, and the result of this detection is reported to HARQ controllers 806 that have been prepared for each mobile station.

HARQ controllers 806 both control states for each HARQ process and, upon receiving a HARQ process state notification, update the HARQ process states by means of the procedure shown in FIG. 18. In addition, information relating to the HARQ states of HARQ controllers 806 and information of the buffer states are periodically sent to scheduler 807, and further, when there are ACK/NACK signals to be transmitted, these signals are sent to control signal combiner 809. Scheduler 807 carries out scheduling of each mobile station based on the SI, HARQ states, and buffer states that have been received from each mobile station or the priority of data flow that is reported by the higher-level layer. Any type of generally known scheduling method may be adopted as the scheduling method, including, for example, a method of assigning transmission opportunities in order to mobile stations having data, and a method of assigning transmission opportunities while giving priority to mobile stations that have data with a high degree of priority. Information relating to scheduling is combined with the data of the downlinks for each mobile station in control signal combiner 809, and then, after subjecting the data following combining to transmission processing such as spreading in transmission processor 810, the data are transmitted by means of the downlinks.

FIG. 20 is a block diagram showing the configuration of a mobile station that is used in the present embodiment.

The mobile station is provided with: reception processor 1001 for implementing reception processes such as despreading received signals; control signal separator 1002 for separating received signals that have undergone despreading into data and control signals; HARQ controller 1003 for controlling HARQ processes in the mobile station; TFC selector 1004 for selecting TFC from among reported TFCS; buffer 1005 for storing data to be transmitted; encoding processor 1000 for subjecting the data to be transmitted to an encoding process; retransmission buffer 1007 for storing transmission data for retransmission; control signal combiner 1008 for combining control signals with data that have undergone the encoding process; transmission processor 1009 for subjecting signals from control signal combiner 1008 to a process such as spreading to produce transmission signals; and retransmission wait counter 1010 for counting retransmission waiting.

In the mobile station, reception processor 1001 subjects received signals to reception processing such as despreading, and control signal separator 1002 separates the received signals that have undergone despreading into data and control signals. Of the control signals that have been separated, ACK/NACK and SA are sent to HARQ controller 1003. HARQ controller 1003 updates the states of the relevant HARQ processes in accordance with ACK/NACK. The processing in the mobile station from this point differs greatly depending on whether the state of the HARQ process that is indicated by the SA is the free state or the retransmission state, and the following explanation is therefore divided between these two cases.

When the state of the HARQ process indicated by the SA is the free When the state of the HARQ process indicated by the SA is the free stare, the state of this process is reported together with the maximum transmission rate information contained in the SA to TFC selector 1004. TFC selector 1004 selects TFC in accordance with prescribed standards from among the TFC that are no greater than the maximum TFC indicated by the maximum transmission rate information. At this time, TFC selector 1004 selects TFC by referring to the degree of priority that is set for each data flow as the selection criteria, whereby data flow having a higher degree of priority has a higher transmission rate, and the corresponding TFCI is transmitted to control signal coordinator 1008. TFC selector 1004 further refers to buffer 1005, and when there are no data in buffer 1005 that are to be transmitted, TFC selector 1004 sends TFCI0, which is a free state notification, to control signal combiner 1008. The selected TFC is further reported to buffer 1005, and data are extracted in accordance with the TFC from buffer 1005 and sent to encoding processor 1006. At this time, a copy of the extracted data block is stored in retransmission buffer 1007.

When the State of the HARQ Process Indicated by the SA is the Retransmission State:

When the state of the HARQ process indicated by the SA is the retransmission state, the state of this process is reported together with the maximum transmission rate information contained in the SA to retransmission buffer 1007 from HARQ controller 1003. When the maximum transmission rate is higher than the transmission rate of the relevant retransmission data, the data to be retransmitted are sent from retransmission buffer 1007 to encoding processor 1008. After undergoing encoding, these data are combined with control signals such as TFCI and NDI in control signal combiner 1008, subjected to processing such as spreading in transmission processor 1009, and the transmitted. Alternatively, if the maximum transmission rate is lower than the transmission rate of the retransmission data, HARQ controller 1003 reports this information to TFC selector 1004, and TFC selector 1004 then selects TFCI1, which is a retransmission state notification, and sends this notification to control signal combiner 1008.

When there is a Retransmission State HARQ Process:

In addition, when there is a HARQ process of the retransmission state in the mobile station, HARQ controller 1003 checks whether retransmission instructions exist for each transmission timing of the relevant HARQ process or not, and if there are no retransmission instructions, HARQ controller 1003 adds “1” to the value of retransmission wait counter 1010 provided for each HARQ process. When retransmission wait counter 1010 exceeds a prescribed maximum number N of retransmission waiting, HARQ controller 1003 reports this situation to TFC selector 1004, and TFC selector 1004 sends TFCI1, which is the retransmission state notification, to control signal combiner 1008.

Control signal combiner 1008 combines TFCI and NDI and data blocks to be transmitted, the combined data are subjected to processing such as spreading in transmission processor 1009, and then transmitted by way of an uplink.

As described in the foregoing explanation, the present embodiment can resolve inconsistencies in HARQ process states that occur when the scheduling base station during the SHO state sends NACK and another SHO base station sends ACK, and moreover, when the mobile station does not have new data that should be transmitted. Since the proportion of SHO area in a WCDMA system is typically 40 to 60% and it is difficult to switch scheduling base stations at high speed according to fluctuation in the propagation loss, it is highly likely that the above-described situation occurs. In this situation, the base station pointlessly assigns resources to a mobile station that does not have data that should be transmitted, and to this extent, resources cannot be assigned to mobile stations that hold data that should be transmitted, whereby the efficiency of utilization of resources falls and system throughput deteriorates. The present embodiment can resolve these situations and thus improve system throughput. In addition, a similar situation can be caused by a reception error of NACK or ACK in a mobile station. However, the embodiment of the present invention can resolve inconsistencies in the HARQ process states in the event of a reception error of NACK or ACK in a mobile station and can further raise the efficiency of utilization of resources and improve the system throughput.

As a further advantage of the present embodiment, a base station can detect the reception error of an SA in a mobile station. In other words, when a base station, despite having instructed the transmission of a data block by means of an SA, fails to receive a data block or a HARQ process state notification at the indicated timing, the base station can determine that the mobile station was unable to receive the SA. Therefore, in this type of situation, the base station can increase the transmission power of the SA and again transmit the SA and can thereby decrease the error rate of the SA. When the SA is in error, the mobile station is unable to transmit a data block even though the base station is securing resources for the mobile station to which the base station has transmitted the SA. Accordingly, the transmission delay of this mobile station increases, whereby not only does the user throughput fall, but the secured resources cannot be assigned to other mobile stations that are waiting to transmit data, and the overall system throughput therefore falls. The present embodiment can decrease the probability of occurrence of such situations and can therefore increase both system throughput and user throughput and can decrease transmission delay.

Second Embodiment

Explanation next regards the communication control method according to the second embodiment.

The second embodiment assumes the use of time scheduling and the use of asynchronous transmission for HARQ. In addition, mobile stations are assumed to make determinations regarding retransmissions. In other words, the use of a spontaneous retransmission method will be assumed. As in the first embodiment, this second embodiment also uses TFCI to transmit HARQ process state notifications. More specifically, TFCI0 is defined as the free state, and & TFCI1 is defined as the retransmission state.

A mobile station uses a HARQ process state notification in the following cases:

(a) when the mobile station has received ACK, and further, the mobile station has no data in its buffer that should be transmitted;

(b) when the mobile station has received NACK, and further, after receiving the NACK, the maximum transmission rate is continuously lower than the required transmission rate for resending over the interval of W frames; and

(c) when the mobile station is unable to receive ACK or NACK at a prescribed timing T even though the mobile station has transmitted a data block, and further, the maximum transmission rate is continuously lower than the required transmission rate for resending over an interval of W frames from T.

When any one of the above-described conditions (a) to (c) is satisfied, the mobile station transmits TFCI to the base-station to report the state of the relevant HARQ process. Upon receiving the TFCI for reporting the HARQ process state, the base station checks the HARQ process state in that base station, and when an inconsistency has occurred, either corrects the HARQ process state in that base station to match the mobile station or reports the HARQ process state of the base station to the mobile station.

FIG. 21 is a sequence chart showing the exchange of signals between base stations and a mobile station in the SHO state in the second embodiment.

The mobile station and base stations transmit and receive RR and RG at prescribed periods as shown in Steps S1401 and S1402. The mobile station transmits a data block to each base station at any timing and at a transmission rate no greater than the designated maximum transmission rate with NDI=0. In this case, it is assumed that the mobile stator receives NACK from the scheduling base station in Step S1405 and receives ACK from the non-scheduling base station in Step S1406. Accordingly, although a retransmission state occurs at the scheduling base station, the mobile station enters the free state, and an inconsistency in HARQ process states thus occurs. Upon receiving the ACK, the mobile station checks the data in its own buffer, and when there are no data to be transmitted, the mobile station transmits a free state notification, i.e., TFCI0, in Step S1407. This case conforms with the above-described condition (a), and the base station therefore recognizes that the mobile station is in the free state and determines that the mobile station does not hold the data that were to be transmitted. The base station then returns the HARQ process to the free state and terminates the assignment of resources to this mobile station. In this way, inconsistencies between the HARQ process states between the scheduling base station and the mobile station can be resolved in the present embodiment, and the pointless assignment of resources can be avoided.

FIG. 22 is a flow chart showing the process of updating the HARQ process state in the mobile station in the present embodiment.

The mobile station transmit a data block at a transmission rate no greater than the maximum transmission rate permitted at any time in Step S1401 a, and determines whether ACK has been received at the prescribed timing from the base station or not in Step S1402a. When the mobile station has received ACK at the prescribed timing, the mobile station checks the data volume in the buffer of that mobile station in Step S1403a and determines whether there are data that should be transmitted. If there are data that should be transmitted, the mobile station returns to Step S1401a to subsequently transmit the data block, but if there are no data that should be transmitted, the mobile station transmits a free state notification in Step S1404a and ends the process. The base station can detect that the mobile station has completed sending all data in the buffer, and if the base station is in the retransmission state, the base station can correct this state and thus avoid the pointless assignment of resources. As a result, the system throughput increases.

If ACK has not been received in Step S1402a, i.e., if NACK has been received at the prescribed timing, the mobile station determines in Step S1405a whether the maximum transmission rate permitted is adequate for transmitting the data block that should be retransmitted. In this case, when the maximum transmission rate is determined to be sufficient, the mobile station returns to Step S1401a to transmit the retransmission data at any timing. On the other hand, if the maximum transmission rate is not adequate, the mobile station increases the timer by a prescribed time interval in Step S1406 and compares the value of the timer with a prescribed maximum retransmission wait time interval W in Step S1407a. If the value of the timer is not greater than W, the mobile station returns as far as Step S1405a, but if the value of the timer is greater than W, the mobile station transmits a retransmission state notification in Step S1408a. The mobile station then determines whether ACK has been received or not at the prescribed timing in Step S1409a, and if ACK has been received, discards the data block that is being transmitted in Step S1410a and determines whether there are data that should be transmitted in Step S1411a. If it is determined in Step S1411a that there are data that are to be transmitted, the mobile station returns to Step S1401a to continue transmission of data blocks at any timing, but if there are no data to be transmitted, the mobile station proceeds to Step S1404a to transmit a free state notification and ends the process. If it is determined in Step S1409a that ACK has not been received, i.e., if NACK has been received at a prescribed timing, the process of the mobile station returns to Step S1405a.

FIG. 23 is a flow chart showing the processing relating to the reception of data in the base station in the present embodiment.

The base station receives data in Step S1401b and checks whether the TFCI that has been sent together with the data is a HARQ process state notification or not in Step S1402b. If the TFCI is a HARQ process state notification, the base station determines whether this HARQ process state notification is a free state notification or not in Step S1403b, and if a free state notification has been received, the HARQ process state in the base station is also set to the free state in Step S1404b and the base station returns to Step S1401b to receive the next data. Therefore, when the mobile station is in the free state but the base station is in the retransmission state, the pointless assignment of resources for retransmission is circumvented and the system throughput is thus improved.

If it is determined in Step S1403b that the HARQ process state notification is not a free state notification, i.e., if a retransmission state notification has been received, the base station checks the HARQ process state in the base station in Step S1405b to determine whether the base station is in the retransmission state or nor. If the base station is not in the retransmission state, i.e., if it is the free state, the base station transmits ACK in Step S1406b, but if the base station is in the retransmission state, the base station transmits NACK in Step S1407b. In either case, the base station returns to Step S1401b to receive the next data. Accordingly, when the mobile station is waiting to retransmit for a data block that the base station has already completed receiving, the base station can correct the state of the mobile station to the free state. As a result, the situation can be avoided in which the mobile station pointlessly waits for the assignment of retransmission resources and thus presents the transmission of other data, and the user throughput is thus improved.

If it is determined in Step S1402b that the TFCI is not a HARQ process state notification, the base station receives a data block in Step S1408b and determines whether correct reception of this data block was possible or not in Step S1409b. If the base station was able to correctly receive the data block, the base station transmits ACK in Step S1410b, and if the base station was unable to correctly receive, the base station transmits NACK in Step S1411b. In either case, the base station returns to Step S1401b to receive the next data. The base station retransmits the above-described operations.

Thus, when the mobile station is in the retransmission state but the base station fails to recognize this state and does not assign adequate resources for retransmission, the mobile station can -notify the base station that the mobile station is waiting to retransmit; and when the base station has already been able to correctly receive, the base station can send ACK to notify the mobile station and correct the HARQ process of the mobile station. Accordingly, the present embodiment can avoid a situation in which the inability to transmit retransmission data prevents the transmission of other new data and thus improves the user throughput. In addition, a base station can avoid the pointless assignment of resources to this mobile station and thus raise the efficiency of utilization of resources and improve the system throughput.

FIG. 24 shows the configuration of a base station used in this embodiment.

As in the base station shown in FIG. 19, the base station is provided with: reception processor 1501 for carrying out processes such as despreading received signals; control signal separator 1502 for separating received signals that have undergone despreading into control signals and data; decoding processor 1503 for decoding the separated data; buffer 1504 for accumulating data following decoding, one or a plurality of buffers being prepared for each motile station; error detector 1505 for detecting errors in the decoded data; HARQ controller 1506 provided corresponding to each mobile station for managing HARQ process states; scheduler 1507 for carrying out scheduling for each mobile station; encoding processor 1508 for carrying out encoding processes for downlink data; control signal combiner 1509 for combining control signals with downlink data that have undergone encoding; and transmission processor 1510 for carrying out processes such as spreading for output signals from control signal combiner 1509 to produce transmission signals.

In the base station, received signals are subjected to processing such as despreading in reception processor 1501, following which the signals are separated into control signals and data in control signal separator 1502. The separated data are decoded in decoding processor 1503 and then accumulated in buffers 1504, one or a plurality of buffers being provided for each mobile station. At the same time, the decoded data are subjected to error detection by error detector 1505, and the results of this detection are reported to HARQ controllers 1506 that are provided for each mobile station. Of the separated control signals, the RR is sent to scheduler 1507, and the HARQ process state notification and NDI are sent to HARQ controller 1506.

HARQ controller 1506 not only manages the states for each HARQ process, but also changes the state of the relevant HARQ process to the free state upon receiving a free state notification, checks the state of the relevant HARQ process upon receiving a retransmission state notification, generates ACK if this state is the free state and generates NACK if this state is the retransmission state, and sends these ACK and NACK to control signal combiner 1509. Information relating to the HARQ state of HARQ controller 1506 and information of the buffer states are periodically sent to scheduler 1507.

Scheduler 1507 carries out scheduling of each mobile station based on such factors as the RR, HARQ state and the buffer states that have been received from each mobile station, or the degree of priority of data flow that is reported by the higher-level layer. As the scheduling method, any generally known scheduling method may be adopted including a method of assigning transmission opportunities in order to mobile station having data or a method of assigning transmission opportunities that gives priority to mobile stations having data with a high degree of priority. Information relating to scheduling is combined in control signal combiner 1509 with data of downlink for each mobile station, and after undergoing combining, the data are subjected to a transmission process such as spreading in transmission processor 1510 and then transmitted by means of downlinks.

FIG. 25 shows the configuration of a mobile station used in the present embodiment.

The mobile station is provided with: reception processor 1601 for implementing a reception process such as despreading for received signals; control signal separator 1602 for separating the received signals that have undergone despreading into data and control signals; HARQ controller 1603 for controlling the HARQ processes in the mobile station; TFC selector 1604 for selecting TFC from among the reported TFCS; buffer 1605 for storing data to be transmitted; encoding processor 1606 for carrying out an encoding process upon data to be transmitted; retransmission buffer 1607 for storing transmission data for retransmission; control signal combiner 1608 for combining control signals with data that have undergone the encoding process; and transmission processor 1609 implementing a process such as spreading upon signals from control signal combiner 1608 to produce transmission signals.

In the mobile station, received signals are subjected to a reception process such as despreading by reception processor 1601, and control signal separator 1602 then separates the data and control signals from the received signals that have undergone despreading. Of the separated control signals, ACK and NACK are sent to HARQ controller 1603. HARQ controller 1603 updates the state of the relevant HARQ process in accordance with the ACK/NACK. When ACK has been received, HARQ controller 1603 reports this infuriation to TFC selector 1604, and TFC selector 1604 checks the data volume in buffer 1605 and sends TFCI0, which is a free state notification, to control signal combiner 1608 when there are no new data to be transmitted. Of the -separated control signals, RG is sent to TFC selector 1604, and the maximum transmission rate in TFG selector 1604 is updated by means of this RG. Based on information regarding the presence or absence of retransmission data that is reported by HARQ controller 1603, TFC selector 1604 further determines to transmit retransmission data if retransmission data exist and otherwise determines to transmit new data.

When transmitting retransmission data, TFC selector 1604 checks whether the use of the same TFC as when initially transmitting is permitted, and if the use is not permitted, advances the retransmission wait timer (not shown) by a prescribed time interval. When the value of the timer equals or exceeds a prescribed maximum wait time interval, TFC selector 1604 transmits TFCI1, which is a retransmission state notification, to control signal combiner 1608. When the same TFC that was used when initially transmitting can be used, TFC selector 1604 is caused to extract the retransmission data block from retransmission buffer 1607 and send data block to encoding processor 1606.

On the other hand, when transmitting new data, TFC selector 1604 selects TFC in accordance with prescribed criteria from among the TFC that is not greater than the maximum TFC that has been updated by RG. At this time, TFC selector 1604 refers to the degree of priority set for each data flow as the selection criteria and selects TFC such that data flows with higher priority have higher transmission rates. TFC selector 1604 reports the selected TFC to buffer 1605 such that data are extracted from the buffer and sent to encoding processor 1606. At this time, a copy of the extracted data block is stored in retransmission buffer 1607.

The data block that is sent to encoding processor 1606 is encoded, combined with control signals such as TFCI, NDI, RV, and HARQ ID in control signal combiner 1608, subjected to a process such as spreading in transmission processor 1609, and then transmitted.

As in the first embodiment, the present embodiment as described in the foregoing explanation can resolve inconsistencies in HARQ process states that occur when the scheduling base station during a SHO state sends NACK and another SHO base station sends ACK, and moreover, the mobile station does not have new data to be transmitted. When inconsistencies in HARQ process states occur, base stations pointlessly assign resources to mobile stations that do not have data to be transmitted, and to this extent, resources cannot be assigned to mobile stations that have data that should be transmitted, whereby the efficiency of utilization of resources falls and the system throughput deteriorates. The present embodiment enables the resolution of such situations and thus improves system throughput. In addition, a similar situation occurs due to reception errors of NACK or ACK in a mobile station, but the present embodiment enables a resolution of inconsistencies in HARQ process states when a reception error of NACK/ACK occurs in a mobile station, thereby raising the efficiency of utilization of resources and improving system throughput.

Third Embodiment

Explanation next regards the communication control method of the third embodiment.

As in the first embodiment, in the third embodiment, the use of time/transmission rate scheduling is assumed, and HARQ is assumed to employ synchronous transmission. Further, base stations are assumed to command regarding retransmissions. In other words, the use of a base station-controlled retransmission method will be assumed.

In the third embodiment, when a mobile station receives NACK from the scheduling base station and receives ACK from another SHO base station, and moreover, does not have data in its buffer, the mobile station transmits a “no data” notification as the HARQ process state notification. TFCI0 is used as the “no data” notification, and upon receiving TFCI0 from a mobile station, a base station corrects the relevant HARQ process to the free state and does not assign retransmission resources.

The adoption of the above-described “no data” notification enables a circumvention of the pointless assignment of resources resulting from inconsistencies in the HARQ process between a scheduling base station and a mobile station. Further, in contrast to the first embodiment, problems resulting from reception errors of ACK or NACK cannot be resolved, but other measures cad be devised such as increasing the transmission power of ACK/NACK or redundancy to lower the error rate of ACK/NACK. In contrast, inconsistencies in HARQ process that occur during SHO are a fundamental problem that cannot be avoided by other methods. Therefore, the present embodiment can avoid the pointless assignment of resources by the scheduling base station during SHO and thus improve system throughput while reducing the amount of proms state notifications transmitted by mobile stations.

In addition, although TFCI is used as the “no data” notification in the present embodiment, “0” size in BOI that is included in SI may also be defined for use as the “no data” notification.

Fourth Embodiment

Explanation next regards the communication control method according to the fourth embodiment.

As in the first embodiment, the use of time/transmission rate scheduling will be assumed in the fourth embodiment, and the use of synchronous transmission will be assumed for HARQ. In addition, base stations will be assumed to command relating to retransmissions. In other words, the use of a base station-controlled retransmission method will be assumed.

In the fourth embodiment, the mobile station reports the state of the HARQ process at a prescribed period. FIG. 26 shows an example of the transmission of a HARQ process state notification for a case in which four HARQ processes are set in the mobile station.

In the present embodiment, each HARQ process sends a HARQ process state notification once every five times. The HARQ processes for which state notifications are transmitted are indicated by the frames with hatching in the figure. TFCI0 and TFCI1 are used as the HARQ process state notifications, as in the first embodiment, TFCI0 being the free state notification and TFCI1 being the retransmission state notification. When the transmission timing for a HARQ process state notification arrives, the mobile station uses these HARQ process state notifications to report the state at that time to the base station. In the other frames, the mobile station transmits data in accordance with the instructions of the base station. The transmission timing of the HARQ process state notifications is already known in the base station, and the base station therefore does not perform scheduling of data transmission at these timings. Upon receiving a HARQ process state notification, the base station checks the current state of the relevant HARQ process, and corrects the state to that of the notification from the mobile station if the state is different.

The present embodiment enables the base station and mobile station to correct inconsistencies in HARQ process states at a prescribed period. As a result, the present embodiment enables circumvention of pointless assignment of resources and improves throughput.

Fifth Embodiment

As in the first embodiment, the fifth embodiment assumes the use of time/transmission rate scheduling and further assumes the use of synchronous transmission for HARQ. Further, the base station is assumed to command relating to retransmissions, i.e., the use of a base station-controlled retransmission method is assumed.

In the first embodiment, a mobile station, upon receiving an SA, transmitted a HARQ process state notification at the transmission timing designated by SA, but in the fifth embodiment, a mobile station transmits a HARQ process state notification when there are no data to be transmitted at time T at which SA is received, and further, when no data that should be transmitted occur within a prescribed time interval from time T.

As a result, in addition to the advantages of the first embodiment, the present embodiment can avoid the frequent transmission of HARQ process state notification.

Sixth Embodiment

As in the second embodiment, the sixth embodiment assumes the use of time scheduling and the use of asynchronous transmission for HARQ. In addition, mobile stations are to make determinations relating to retransmissions, i.e., the use of a spontaneous transmission method is assumed.

In the second embodiment, a mobile station transmitted a HARQ process state notification immediately after receiving ACK, but in the sixth embodiment, a mobile station transmits a HARQ process state notification if there are no data to be transmitted at time T when ACK is received, and further, when no data to be transmitted occur within a prescribed time interval from time T.

As a result, in addition to the advantages obtained by the second embodiment, the present embodiment can further avoid the frequent transmission of HARQ process state notifications.

The base station of a cellular system is typically provided with a computer in addition to an antenna and radio transceiver for controlling the operations of the base station. Accordingly, the base station in each of the above-described embodiment may be realized by the reading and execution of programs for realizing the above-described functions by a computer that constitutes the base station. Similarly, the mobile station in each of the above-described embodiments may be realized by the reading and execution of programs for realizing the above-described functions by a computer that constitutes the mobile station.

Such programs may for example be recorded on a recording medium that can be read by a computer, this recording medium then being mounted in a computer and thus read into the computer. Alternatively, such programs may be read into a computer by way of a network such as the Internet. Accordingly, such programs, recording media in which such programs are recorded, and program products that include such programs are all included within the scope of the present invention.

Claims

1. A communication control method comprising the steps of: a base station notifying a mobile station of resource assignment information indicating assignment of radio resources;said mobile station transmitting data in accordance with said resource assignment information;said base station transmitting to said mobile station a delivery confirmation signal according to whether said data has been correctly received or not; andsaid mobile station transmitting a process state notification to said base station in accordance with said delivery confirmation signal.

2. A communication control method in a radio communication system having a base station, and a mobile station in which a radio channel is set to said base station; said communication control method comprising the steps of: said base station notifying said mobile station of transmission resource assignment information indicating assignment of transmission resources;said mobile station transmitting a data block in accordance with said transmission resource assignment information;said base station transmitting a delivery confirmation signal indicating whether said data block has been correctly received or not;said mobile station retransmitting said data block upon receiving said delivery confirmation signal indicating a reception error;said mobile station completing the transmission of said data block upon receiving said delivery confirmation signal indicating correct reception;said mobile station transmitting a transmission process state notification reporting whether said mobile station is in a retransmission state, which is a state of waiting for a retransmission, or a free state, which is a state of not waiting for a retransmission; andsaid base station determining the assignment of said transmission resources to said mobile station in accordance with the transmission process state in said mobile station.

3. The communication control method according to claim 2, wherein said mobile station transmits said transmission process state notification at a prescribed period.

4. The communication control method according to claim 2, wherein said mobile station transmits said transmission process state notification according to reception of said delivery confirmation signal.

5. The communication control method according to claim 2 wherein said mobile station transmits said transmission process state notification when there is no data to be transmitted in a buffer of said mobile station at ACK reception time, which is time of receiving said delivery confirmation signal indicating correct reception, and moreover, data to be transmitted has not occurred within a prescribed time interval from said ACK reception time.

6. The communication control method according to claim 2, wherein said mobile station transmits said transmission process state notifications when resources have not been assigned that are necessary for a retransmission corresponding to said delivery confirmation signal indicating said reception error during a prescribed time interval from NACK reception time, which is time of receiving said delivery confirmation signal indicating a reception error.

7. The communication control method according to claim 2, wherein said mobile station transmits said transmission process state notification and then, upon receiving said delivery confirmation signal indicating correct reception at a prescribed timing, discards data that are being transmitted and halts retransmission.

8. The communication control method according to claim 2, wherein said mobile station transmits said transmission process state notification when there are no data to be transmitted in a buffer of said mobile station at an assignment reception time, which is time of receiving said transmission resource assignment information, and moreover, no data to be transmitted occurs within a prescribed time interval from the SA reception time.

9. The communication control method according to claim 2, wherein said mobile station, upon having received said transmission resource assignment information when there are no data to be transmitted, transmits a first transmission process state notification, and upon having received said transmission resource assignment information when there are data to be transmitted but said mobile station does not transmit the data, transmits a second transmission process state notification.

10. The communication control method according to claim 2, wherein when said base station transmits said transmission resource assignment information, and then receives neither a data block nor said transmission process state notification from said mobile station over a prescribed interval, said base station increases transmission power of said transmission resource assignment information by a prescribed value and then transmits.

11. The communication control method according to claim 9, wherein said base station, upon receiving said second transmission process state notification, lower priority of assigning transmission resources to said data block.

12. The communication control method according to claim 2, wherein maximum transmission rate and transmission time that said mobile station is permitted to use are assigned as said transmission resources.

13. The communication control method according to claim 2, wherein maximum transmission rate that said mobile station is permitted to use is assigned as said transmission resources.

14. A radio communication system comprising: a base station which transmits radio resource assignment information to a mobile station, and transmits a delivery confirmation signal according to whether data which said mobile station has transmitted is correctly received or not; anda mobile station which transmits data block to said base station in accordance with said radio resource assignment information, receives said delivery confirmation signal, and transmits a process state notification to said base station in accordance with said delivery confirmation signal.

15. A radio communication system comprising: a base station; anda mobile station in which a radio channel is set to said base station, that transmits a data block to said base station in accordance with transmission resource assignment information from said base station, that retransmits said data block upon receiving from said base station said delivery confirmation signal indicating a reception error, that completes transmission of said data block upon receiving said delivery confirmation signal indicating correct reception, and that transmits a transmission process state notification for

16. A base station comprising: means for transmitting radio resource assignment information to a mobile station;means for transmitting a delivery confirmation signal according to whether data which said mobile station has transmitted is correctly received or not; andmeans for receiving a process state notification which said mobile station transmits in accordance with said delivery confirmation signal.

17. A base station in which a radio channel is set to a mobile station, comprising: means for receiving from said mobile station a data block and transmission process state notification reporting whether said mobile station is in a retransmission waiting state or not;means for determining whether said data block has been correctly received or not;means for determining the assignment of transmission resources to said mobile station according to said transmission process state notification; andmeans for both reporting transmission resource assignment information to said mobile station and for transmitting delivery confirmation signals indicating whether said data blocks have been correctly received or not.

18. A mobile station comprising: means for transmitting data to a base station in accordance with radio resource assignment information which said base station transmits;means for receiving a deliver confirmation signal for said date, said base station transmitting said deliver confirmation signal; andmeans for transmitting a process state notification to said base station in accordance with said delivery confirmation signal.

19. A mobile station in which a radio channel is set to a base station, comprising: storage means for storing data to be transmitted;means for receiving from said base station transmission resource assignment information and delivery confirmation signals;means for transmitting data in said storage means as a data block in accordance with said transmission resource assignment information, retransmitting said data block upon receiving said delivery confirmation signal indicating a reception error, and ending transmission of said data block upon receiving said delivery confirmation signal indicating correct reception; andmeans for transmitting a transmission process state notification for reporting whether said mobile station is in a retransmission waiting state or not.

20. A program that can be executed by a computer that forms a base station, said program causing said computer to execute processes of: transmitting radio resource assignment information to a mobile station;transmitting a delivery confirmation signal according to whether data which said mobile station has transmitted is correctly received or not; andreceiving a process state notification which said mobile station transmits in accordance with said delivery confirmation signal.

21. A program that can be executed by a computer that forms a base station in which a radio channel is set to a mobile station, said program causing said computer to execute processes of: receiving from said mobile station a data block and transmission process state notification for reporting whether the mobile station is in a retransmission waiting state or not;determining whether said data block has been received correctly or not;determining assignment of transmission resources to said mobile station according to said transmission process state notification; andboth reporting transmission resource assignment information to said mobile station and transmitting delivery confirmation signals indicating whether said data block has been correctly received or not.

22. A program that can be executed by a computer that forms a mobile station, said program causing said computer to execute processes of: transmitting data to a base station in accordance with radio resource assignment information which said base station transmits;receiving a deliver confirmation signal for said data, said base station transmitting said deliver confirmation signal; andtransmitting a process state notification to said base station in accordance with said delivery confirmation signal.

23. A program that can be executed by a computer that forms a mobile station in which a radio channel is set to a base station, said program causing said computer to execute processes of: storing, in a storage unit, data to be transmitted;receiving from said base station transmission resource assignment information and delivery confirmation signals;transmitting data in said storage unit as a data block in accordance with said transmission resource assignment information, retransmitting said data block upon receiving said delivery confirmation signal indicating a reception error, and ending transmission of said data block upon receiving said delivery confirmation signal indicating correct reception; andtransmitting a transmission process state notification for reporting whether said mobile station is in a retransmission waiting state or not.