Communication device, processing device and method for transmitting data unit

Abstract

A communication device, processing device or method constructs M RLC PDUs including M RLC SDUs, respectively, where M is larger than 1; submits, for a transmission opportunity, only L RLC PDUs for L RLC SDUs with lowest L SNs among the M RLC PDUs to a MAC layer, where L<M and the L RLC PDUs include a first RLC PDU having a poll to trigger status reporting at a receiving device; transmits the L RLC PDUs to the receiving device; constructs a second RLC PDU including a second RLC SDU having a highest SN among SNs of RLC SDUs submitted to the MAC layer, when the poll retransmission timer started upon submitting the first RLC PDU having the poll expires and no new RLC SDU or RLC SDU segment can be transmitted.

What is claimed is: 
     
         1 . A method performed by an acknowledge mode (AM) radio link control (RLC) entity of a user equipment (UE) in a wireless communication system, the method comprising:
 generating RLC protocol data units (PDUs) for RLC service data units (SDUs);   based on a transmission opportunity being notified by a medium access control (MAC) layer of the UE, submitting one or more RLC PDUs among the generated RLC PDUs to the MAC layer, wherein the one or more RLC PDUs includes a first RLC PDU having a poll to trigger status reporting at a peer AM RLC entity;   based on the first RLC PDU being submitted to the MAC layer, starting a poll retransmission timer;   based on (i) expiration of the poll retransmission timer, and (ii) a state in which no new RLC SDU can be transmitted, considering an RLC SDU which has a highest sequence number (SN) among one or more RLC SDUs included in the one or more RLC PDUs for retransmission;   generating a second RLC PDU comprising the considered RLC SDU; and   submitting the second RLC PDU to the MAC layer.   
     
     
         2 . The method according to  claim 1 , wherein each of the RLC PDUs is generated for a respective RLC SDU without waiting for notification from the MAC layer regarding the transmission opportunity. 
     
     
         3 . The method according to  claim 1 , wherein generating the second RLC PDU comprises including the poll into the second RLC PDU. 
     
     
         4 . The method according to  claim 1 , further comprising:
 setting a first state variable to 1+a highest SN among the generated RLC PDUs,   wherein the first state variable holds an SN that is to be assigned for a newly generated RLC PDU, and   wherein the first state variable is updated whenever an RLC PDU, which includes an RLC SDU or a last segment of an RLC SDU, is generated with an SN that is equal to the first state variable.   
     
     
         5 . The method according to  claim 1 , wherein the highest SN of the considered RLC SDU is smaller than a highest SN among SNs of RLC SDUs included in the generated RLC PDUs. 
     
     
         6 . The method according to  claim 1 ,
 wherein the one or more RLC PDUs is submitted to the MAC layer in a state in which the one or more RLC PDUs submitted to the MAC layer comprise more than one RLC PDU having the poll, and   the method further comprises:   setting a second state variable to a highest SN among the more than one RLC PDU having the poll based on submitting the more than one RLC PDU having the poll for the transmission opportunity.   
     
     
         7 . A user equipment (UE) in a wireless communication system, the UE comprising:
 a transceiver;   at least one processor; and   at least one computer memory that is operably connectable to the at least one processor and that has stored thereon instructions which, when executed, cause the at least one processor to perform, by an acknowledge mode (AM) radio link control (RLC) entity of the UE, operations comprising:   generating RLC protocol data units (PDUs) for RLC service data units (SDUs);   based on a transmission opportunity being notified by a medium access control (MAC) layer of the UE, submitting one or more RLC PDUs among the generated RLC PDUs to the MAC layer, wherein the one or more RLC PDUs includes a first RLC PDU having a poll to trigger status reporting at a peer AM RLC entity;   based on the first RLC PDU being submitted to the MAC layer, starting a poll retransmission timer;   based on (i) expiration of the poll retransmission timer, and (ii) a state in which no new RLC SDU can be transmitted, considering an RLC SDU which has a highest sequence number (SN) among one or more RLC SDUs included in the one or more RLC PDUs for retransmission;   generating a second RLC PDU comprising the considered RLC SDU; and   submitting the second RLC PDU to the MAC layer.   
     
     
         8 . The UE according to  claim 7 , wherein each of the RLC PDUs is generated for a respective RLC SDU without waiting for notification from the MAC layer regarding the transmission opportunity. 
     
     
         9 . The UE according to  claim 7 , wherein generating the second RLC PDU comprises including the poll into the second RLC PDU. 
     
     
         10 . The UE according to  claim 7 , the operations further comprise:
 setting a first state variable to 1+a highest SN among the generated RLC PDUs,   wherein the first state variable holds an SN that is to be assigned for a newly generated RLC PDU, and   wherein the first state variable is updated whenever an RLC PDU, which includes an RLC SDU or a last segment of an RLC SDU, is generated with an SN that is equal to the first state variable.   
     
     
         11 . The UE according to  claim 7 , wherein the highest SN of the considered RLC SDU is smaller than a highest SN among SNs of RLC SDUs included in the generated RLC PDUs. 
     
     
         12 . The UE according to  claim 7 ,
 wherein the one or more RLC PDUs is submitted to the MAC layer in a state in which the one or more RLC PDUs submitted to the MAC layer comprise more than one RLC PDU having the poll, and   the operations further comprise:   setting a second state variable to a highest SN among the more than one RLC PDU having the poll based on submitting the more than one RLC PDU having the poll for the transmission opportunity.   
     
     
         13 . An apparatus for a user equipment (UE), the apparatus comprising:
 at least one processor; and   at least one computer memory that is operably connectable to the at least one processor and that has stored thereon instructions which, when executed, cause the at least one processor to perform, by an acknowledge mode (AM) radio link control (RLC) entity of the apparatus, operations comprising:   generating RLC protocol data units (PDUs) for RLC service data units (SDUs);   based on a transmission opportunity being notified by a medium access control (MAC) layer of the apparatus, submitting one or more RLC PDUs among the generated RLC PDUs to the MAC layer, wherein the one or more RLC PDUs includes a first RLC PDU having a poll to trigger status reporting at a peer AM RLC entity;   based on the first RLC PDU being submitted to the MAC layer, starting a poll retransmission timer;   based on (i) expiration of the poll retransmission timer, and (ii) a state in which no new RLC SDU can be transmitted, considering an RLC SDU which has a highest sequence number (SN) among one or more RLC SDUs included in the one or more RLC PDUs for retransmission;   generating a second RLC PDU comprising the considered RLC SDU; and   submitting the second RLC PDU to the MAC layer.   
     
     
         14 . A computer readable storage medium storing at least one computer program comprising instructions that, when executed by at least one processor of a user equipment (UE) in a wireless communication system, cause the at least one processor to perform operations by an acknowledge mode (AM) radio link control (RLC) entity of the UE, the operations comprising:
 generating RLC protocol data units (PDUs) for RLC service data units (SDUs);   based on a transmission opportunity being notified by a medium access control (MAC) layer of the UE, submitting one or more RLC PDUs among the generated RLC PDUs to the MAC layer, wherein the one or more RLC PDUs includes a first RLC PDU having a poll to trigger status reporting at a peer AM RLC entity;   based on the first RLC PDU being submitted to the MAC layer, starting a poll retransmission timer;   based on (i) expiration of the poll retransmission timer, and (ii) a state in which no new RLC SDU can be transmitted, considering an RLC SDU which has a highest sequence number (SN) among one or more RLC SDUs included in the one or more RLC PDUs for retransmission;   generating a second RLC PDU comprising the considered RLC SDU; and   submitting the second RLC PDU to the MAC layer.