Abstract:
There are disclosed a resource allocation method and a base station device for realizing an effective resource allocation for reducing delay time and overhead. In this device, when a base station ( 11 ) has received an erroneous data packet ( 22 ) from a mobile station ( 10 ), prior to the initial transmission of the data packet ( 22 ), the base station ( 11 ) allocates a resource to the mobile station ( 10 ) according to contents (such as transmission packet length and priority) of a reservation signal ( 20 ) reported from the mobile station ( 10 ) and transmits an allocation signal ( 21 ) and NACK ( 23 - 1 ) to the mobile station ( 10 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a resource allocation method for allocating resources required for a base station to communicate with a mobile station, and to a base station apparatus. 
       BACKGROUND 
       [0002]    As a conventional resource allocation method, a technique disclosed in Patent Document 1 is proposed. The resource allocation method as described in Patent Document 1 will be described below in detail with reference to  FIG. 1 . As shown in  FIG. 1 , before transmitting data packet  52 - 1 , a mobile station transmits reservation signal  50  storing a user ID, priority, transmission packet length and other control data to a base station as reservation signal  50 - 1 . 
         [0003]    The base station receiving reservation signal  50 - 1  from the mobile station allocates resources (such as code, power and time) enabling the mobile station to transmit a packet with the transmission packet length included in reservation signal  50 - 1 , according to the priority included in reservation signal  50 - 1 , and transmits allocation signal  51 - 1  to the mobile station. 
         [0004]    Next, the mobile station receiving allocation signal  51 - 1  from the base station transmits data packet  52 - 1  to the base station according to the conditions (such as code, power, time and modulation scheme) of received allocation signal  51 - 1 . 
         [0005]    In this case, when the base station erroneously receives data packet  52 - 1  transmitted from the mobile station, the base station transmits negative acknowledgement signal (NACK)  53 - 1  to the mobile station. The mobile station receiving negative acknowledge signal (NACK)  53 - 1  recognizes that data packet  52 - 1  is not received correctly at the base station, and transmits reservation signal  50 - 2  to the base station to receive resource allocation from the base station assuming that data packet  52 - 2  is transmitted again. Herein, data packet  52 - 2  has the same data content as that of data packet  52 - 1 . 
         [0006]    The base station receiving reservation signal  50 - 2  from the mobile station allocates resources (such as code, power and time) enabling the mobile station to transmit a packet with the transmission packet length included in reservation signal  50 - 2 , according to the priority included in reservation signal  50 - 2 , and transmits allocation signal  51 - 2  to the mobile station. 
         [0007]    The mobile station receiving allocation signal  51 - 2  from the base station transmits data packet  52 - 2  for retransmission to the base station according to the conditions (such as code, power, time and modulation scheme) of received allocation signal  51 - 2 . 
         [0008]    When the base station correctly receives retransmission data packet  52 - 2  transmitted from the mobile station, the base station transmits acknowledgment signal (ACK)  53 - 2  to the mobile station. 
         [0009]    Thus, when the base station erroneously receives a data packet transmitted from the mobile station, a series of processing (transmission of a reservation signal from the mobile station to the base station, transmission of an allocation signal from the base station to the mobile station, transmission of a data packet from the mobile station to the base station, and transmission of a negative acknowledgment signal (NACK) from the base station to the mobile station) is repeated. 
         [0010]    By using this technique, the base station allocates resources to mobile stations according to the priority included in a reservation signal from the mobile station, so that it is possible to implement fine resource allocation suitable for each application. 
       PATENT DOCUMENT 1: JAPANESE PATENT APPLICATION LAID-OPEN NO. 2004-128967 
     SUMMARY 
       [0011]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
         [0012]    However, in the above-mentioned resource allocation method as described in Patent Document 1, when a mobile station receives resource allocation to transmit retransmission data packet  52 - 2 , it is necessary for the mobile station to transmit reservation signal  50 - 2  again to the base station and receive allocation signal  51 - 2  in response to reservation signal  50 - 2  from the base station. In other words, in order to transmit a retransmission data packet, the above-mentioned series of processing is repeated from the beginning, and problems arise that the delay time increases, and that overhead which becomes processing load, increases. 
         [0013]    It is therefore an object of the present invention to provide a resource allocation method and a base station apparatus for implementing efficient resource allocation which shortens the delay time and reduces overhead. 
         [0014]    The resource allocation method of the present invention includes: transmitting a reservation signal including a transmission packet length to a base station apparatus from a mobile station apparatus prior to first transmission of a data packet; and, when the base station apparatus detects an error in the data packet transmitted from the mobile station apparatus, transmitting a negative acknowledgement signal for reporting the error of the data packet to the mobile station apparatus from the base station apparatus, and allocating resources to the mobile station apparatus that retransmits the data packet where the error is detected based on the reservation signal. 
         [0015]    According to the present invention, when an error is detected in a data packet transmitted from a mobile station, by allocating resources to the mobile station that retransmits the same data packet based on a reservation signal acquired prior to first transmission of the data packet where the error is detected, without using a reservation signal for retransmission from the mobile station, the mobile station does not need to retransmit a reservation signal to the base station apparatus, so that it is possible to correspondingly reduce the delay time for transmitting a data packet and decrease overhead. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0016]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0017]      FIG. 1  is a sequence diagram for explanation of a resource allocation method described in Patent Document 1; 
           [0018]      FIG. 2  is a sequence diagram for explanation of a resource allocation method according to one embodiment of the present invention; 
           [0019]      FIG. 3  is a block diagram showing a configuration of a base station apparatus according to one embodiment of the present invention; 
           [0020]      FIG. 4  is provided for explanation of tables; and 
           [0021]      FIG. 5  is a flowchart illustrating packet reception operation in the base station. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    An embodiment of the present invention will be specifically described below with reference to the accompanying drawings. 
         [0023]      FIG. 2  is a sequence diagram for explanation of a resource allocation method according to one embodiment of the present invention. In the figure, reservation signal  20  transmitted to base station  11  from mobile station  10  before mobile station  10  transmits a data packet to base station  11 , includes a user ID, sequence number, priority, transmission packet length, the number of retransmissions and other control data. Herein, the sequence number is a sequence number of a data packet to be transmitted, and the number of retransmissions is determined by allowable delay amount of the data to be transmitted. 
         [0024]    As a specific sequence, base station  11  receiving reservation signal  20  from mobile station  10  allocates resources (such as code, power and time) required for mobile station  10  to transmit a packet with the transmission packet length included in reservation signal  20 , and transmits allocation signal  21 - 1  to mobile station  10 . 
         [0025]    Mobile station  10  receiving allocation signal  21 - 1  from base station  11  transmits data packet  22 - 1  to base station  11 , according to conditions (such as code, power, time and modulation scheme) of received allocation signal  21 - 1 . 
         [0026]    When base station  11  erroneously receives data packet  22 - 1  transmitted from mobile station  10 , base station  11  transmits negative acknowledgement signal (NACK)  23 - 1  to mobile station  10 , allocates resources required for mobile station  10  to transmit retransmission packet  22 - 2  according to the transmission packet length included in reservation signal  20 , and further takes into consideration current channel quality information (described later), and transmits allocation signal  21 - 2  to mobile station  10 . In this case, the data content of retransmission data packet  22 - 2  is the same as that of data packet  22 - 1 . 
         [0027]    Mobile station  10  receiving allocation signal  21 - 2  from base station  11  transmits retransmission data packet  22 - 2  according to the conditions of received allocation signal  21 - 2 . When base station  11  correctly receives data packet  22 - 2  transmitted from mobile station  10 , base station  11  transmits acknowledgement signal (ACK)  23 - 2  to mobile station  10 . In addition, when mobile station  10  can receive neither ACK nor NACK due to influence of noise between mobile station  10  and base station  11 , mobile station  10  transmits again reservation signal  20  to base station  11  as in first transmission. 
         [0028]    Thus, when base station  11  transmits negative acknowledgment signal (NACK)  23 - 1  to mobile station  10 , base station  11  transmits the allocation signal of resources according to the data packet length included in the last reservation signal, and therefore mobile station  10  does not need to transmit again the reservation signal to base station  11 . 
         [0029]      FIG. 3  is a block diagram mainly showing a configuration of the base station apparatus according to one embodiment of the present invention. In the figure, each arrow between blocks indicates the flow of a signal together with the connection. In  FIG. 3 , mobile station  10  has transmitting section  101  and receiving section  102 . 
         [0030]    Transmitting section  101  transmits signals such as reservation signal  20  and data packets  22 - 1  and  22 - 2  (hereinafter, collectively referred to as data packet  22 ) to base station  11  using the uplink channel. 
         [0031]    Receiving section  102  receives signals such as allocation signals  21 - 1  and  21 - 2  (hereinafter, collectively referred to as allocation signal  21 ), acknowledgement signal (ACK)  23 - 1  and negative acknowledgment signal (NACK)  23 - 2  (hereinafter, collectively referred to as acknowledge signal  23 ) transmitted from base station  11  using the downlink channel, and analyzes the signals. 
         [0032]    On the other hand, base station  11  has receiving section  111 , transmitting section  112 , signal converting section  113 , signal analyzing section  114 , channel quality analyzing section  115 , allocation determining section  116 , CRC determining section  117 , retransmission information table managing section  118 , radio resource managing section  119 , control signal generating section  120  and channel quality table managing section  121 . 
         [0033]    Receiving section  111  receives signals such as reservation signal  20  and data packet  22  transmitted from mobile station  10  using the uplink channel, and transfers the received signal to signal converting section  113  and channel quality analyzing section  115 . 
         [0034]    Transmitting section  112  transmits signals such as allocation signal  21  and acknowledge signal (ACK, NACK)  23  transferred from signal converting section  113  to mobile station  10  using the downlink channel. 
         [0035]    Signal converting section  113  performs converting processing (such as despreading, demodulation and decoding processing) on the signals such as reservation signal  20  and data packet  22  transferred from receiving section  111  and transfers the results to signal analyzing section  114 . Further, signal converting section  113  performs converting processing (such as spreading, modulation and coding processing) on a control signal transferred from control signal generating section  120  and the downlink data packet, to obtain signals such as allocation signal  21  and acknowledge signal (ACK, NACK)  23  transferred to transmitting section  112 . 
         [0036]    Channel quality analyzing section  115  analyzes channel quality typified by a S/N ratio (Signal to Noise Ratio) and the like of a signal such as reservation signal  20  and data packet  22  transferred from receiving section  111 , and reports the channel quality information to signal analyzing section  114 . 
         [0037]    Signal analyzing section  114  associates the signal transferred from signal converting section  113  with the channel quality information reported from channel quality analyzing section  115 . Then, signal analyzing section  114  reports an update signal based on the channel quality information, user ID indicating a transmission source user that transmits the data packet, and the channel quality information to channel quality table managing section  121 . 
         [0038]    Further, signal analyzing section  114  analyzes a type of the signal transferred from signal converting section  113  as to whether the signal is data packet  22  or reservation signal  20 , and, when receiving data packet  22 , transfers the data to CRC determining section  117 . Furthermore, when receiving reservation signal  20 , base station  11  transmits allocation signal  21  to mobile station  10 , and signal analyzing section  114  reports a transmission request signal of data packet  22 , user ID, priority, transmission packet length and channel quality information to allocation determining section  116  and further reports a retransmission information table entry request signal, user ID, sequence number of the data packet, priority, transmission packet length and the number of retransmissions to retransmission information table managing section  118  for the retransmission of data packet  22 . 
         [0039]    Allocation determining section  116  performs scheduling on a plurality of transmission requests reported from signal analyzing section  114  and retransmission information table managing section  118 , according to the user ID, priority, transmission packet length and channel quality information associated with the transmission requests, and an uplink radio resource remaining amount reported from radio resource managing section  119 . In addition, for the transmission request described herein, retransmission information table managing section  118  reports a retransmission request to allocation determining section  116 . Further, in this case, transmission of retransmission data packet  22  is given a higher priority than that of first transmission packet  22 . Allocation determining section  116  reports to control signal generating section  120  a radio resource allocation signal generation request and information (such as power, time, code and modulation scheme) to be stored in an allocation signal for mobile station  10  to transmit data packet  22  to which the allocation is determined. Further, allocation determining section  116  reports an allocated radio resource amount to radio resource managing section  119 . 
         [0040]    CRC determining section  117  makes a CRC determination on the data transferred from signal analyzing section  114 , and, when an error is detected, reports a NACK generation request signal, user ID and a sequence number of the data packet to control signal generating section  120 , and further reports an error detection signal, user ID and the sequence number to retransmission information table managing section  118 . Furthermore, when an error is not detected, CRC determining section  117  reports an ACK generation request signal, user ID and the sequence number to control signal generating section  120 , and further reports a normal reception signal, user ID and the sequence signal to retransmission information table management  118 , and outputs the received data to an upper apparatus as uplink data. 
         [0041]    When the retransmission information table entry request signal is reported from signal analyzing section  114 , retransmission information table managing section  118  writes the user ID, the sequence number, priority, transmission packet length and the number of retransmissions associated with the retransmission information table entry request signal in retransmission information table  30  as new entries as shown in  FIG. 4 . Herein,  FIG. 4A  shows a table managed by retransmission information table managing section  118 , and  FIG. 4B  shows a table managed by channel quality table managing section  121 . 
         [0042]    Further, when an error detection signal for packet data is reported from CRC determining section  117 , and retransmission information table  30  has entries corresponding to the user ID and the sequence number associated with the error detection signal, retransmission information table managing section  118  acquires channel quality information corresponding to the user ID from channel quality table managing section  121 , and further acquires a retransmission request signal, user ID, priority and transmission packet length from the retransmission information table entries, and reports to allocation determining section  116  together with the channel quality information. Then, retransmission information table managing section  118  decrements the number of remaining retransmissions in the entry of the retransmission information table, and, when the number of remaining retransmissions becomes zero, deletes the entries from retransmission information table  30 . Further, when a normal reception signal is reported from CRC determining section  117 , retransmission information table managing section  118  deletes entries corresponding to the user ID and the sequence number associated with the normal reception signal. 
         [0043]    Radio resource managing section  119  manages allocation states of radio resources (such as power, time and code), and reports an uplink radio resource remaining amount to allocation determining section  116 . Further, radio resource managing section  119  updates the allocation states of uplink radio resources using the allocated resource amount (such as power, time and code) reported from allocation determining section  116 . 
         [0044]    Control signal generating section  120  generates an allocation signal when allocation determining section  116  reports the radio resource allocation signal generation request and information (such as power, time, code and modulation scheme) to be stored in the allocation signal, and transfers the signal to signal converting section  113 . Further, when an ACK or NACK generation request signal is reported from CRC determining section  117 , control signal generating section  120  generates an acknowledge signal (ACK or NACK) storing the user ID and the sequence number associated with the ACK or NACK generation request signal and transfers the signal to signal converting section  113 . 
         [0045]    When a channel quality update signal is reported from signal analyzing section  114 , and channel quality table  31  has entries corresponding to the user ID associated with the channel quality update signal as shown in  FIG. 4B , channel quality table managing section  121  updates the channel quality information of the entries to the channel quality information associated with the channel quality update signal. On the other hand, when channel quality table  31  does not have entries corresponding to the user ID associated with the channel quality update signal, channel quality table managing section  121  writes the user ID and channel quality information as new entries in channel quality table  31 . Further, when retransmission information table managing section  118  searches the channel quality information, channel quality table managing section  121  reports the channel quality information corresponding to the reported user ID to retransmission information table managing section  118 . 
         [0046]    Next, referring to  FIG. 5 , the operation when base station  11  receives a packet (reservation signal  20 , data packet  22 ) will be described. In  FIG. 5 , in step (hereinafter, abbreviated as “ST”)  401 , after receiving section  111  receives a packet (reservation signal  20 , data packet  22 ), channel quality analyzing section  115  measures channel quality of the received signal, and in ST 402 , signal analyzing section  114  determines whether the received signal is data packet  22 . As a result of the determination, when it is determined that the received data is data packet  22 , the flow shifts to ST 403 , and, when it is determined that the received data is not data packet  22 , the flow shifts to ST 414 . 
         [0047]    In ST 403 , CRC determining section  117  determines CRC information associated with the data packet. When a determination result of the CRC information indicates that the data packet has no error, that is, OK, the flow shifts to ST 404 , and, when the determination result of the CRC information indicates that the data packet has an error, that is, NG, the flow shifts to ST 406 . 
         [0048]    In ST 404 , control signal generating section  120  generates acknowledge signal (ACK)  23  and transmits the signal to mobile station  10 . Then, in ST 405 , retransmission information table managing section  118  deletes the retransmission information table entries corresponding to received data packet  22  from retransmission information table  30 , and the processing is finished. 
         [0049]    In ST 406 , control signal generating section  120  generates acknowledge signal (NACK)  23 , and in ST 407 , retransmission information table managing section  118  checks whether retransmission information table entries corresponding to received data packet  22  exist. When the entries do not exist, the processing is finished, and, when the entries exist, the flow shifts to ST 408 . 
         [0050]    In ST 408 , a request for retransmitting received data packet  22  is issued, and in ST 409 , the number of remaining retransmissions of the entries is decremented. 
         [0051]    In ST 410 , it is determined whether the number of remaining retransmissions exceeds zero, and, when the number of remaining retransmissions exceeds zero, the flow shifts to ST 412 , and, when the number of remaining transmissions does not exceed zero, that is, is zero, the flow shifts to ST 411 . 
         [0052]    In ST 411 , entries where the number of remaining retransmissions is zero is deleted from retransmission information table  30 , and in ST 412 , it is determined whether radio resources (power, time and code) are allocated in allocation determining section  116 . When the resources are allocated, the flow shifts to ST 413 , and, when the resources are not allocated, the processing of ST 412  is repeated. 
         [0053]    In ST 413 , control signal generating section  120  generates allocation signal  21  and transmits generated allocation signal  21  and NACK generated in ST 406  to mobile station  10 , and the processing is finished. 
         [0054]    In ST 414 , it is determined that the received signal is not data packet  22  in ST 402 , and therefore it is determined whether the received signal is reservation signal  20 . When the received signal is reservation signal  20 , the flow shifts to ST 415 , and, when the received signal is not reservation signal  20 , the processing is finished. 
         [0055]    In ST 415 , a request for transmitting data packet  22  is issued in response to received reservation signal  20 , and in ST 416 , retransmission information table managing section  118  generates retransmission information table entries corresponding to received reservation signal  20  in retransmission information table  30 . 
         [0056]    In ST 417 , it is determined whether radio resources (power, time and code) are allocated in allocation determining section  116 . When the resources are allocated, the flow shifts to ST 418 , and, when the resources are not allocated, the processing of ST 417  is repeated. 
         [0057]    In ST 418 , control signal generating section  120  generates allocation signal  21  and transmits generated allocation signal  21  to mobile station  10 , and the processing is finished. 
         [0058]    Thus, according to this embodiment, it is possible to perform efficient resource allocation enabling retransmission data packet  22  to be transmitted without mobile station  10  transmitting a reservation signal for retransmission data packet  22  to base station  11 . 
         [0059]    In addition, in the above-mentioned embodiment, whether to perform resource allocation for a retransmission data packet is determined by the number of remaining retransmissions, but may be determined according to elapsed time from the transmission time of the reservation signal. 
         [0060]    The present application is based on Japanese Patent Application No. 2005-010479, filed on Jan. 18, 2005, the entire content of which is expressly incorporated by reference herein. 
         [0061]    A resource allocation method and a base station apparatus according to the present invention are suitable for use in a transmission/receiving apparatus for data packets where the delay time and overhead are reduced. 
         [0062]    While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing form the spirit and scope of the invention.