Method and apparatus for transmitting a buffer status report in a wireless communication system

Abstract

The present disclosure proposes a method for transmitting a buffer status report informing of the data to be transmit in uplink. The method for transmitting buffer status report of a terminal in a wireless communication system includes checking, when allocating uplink resource for new data transmission, whether first buffer status report triggered but not cancelled exists, generating, when the first buffer status report exists, uplink data including the buffer status report, checking whether second buffer status report triggered but not cancelled exist except for the buffers status report included in the uplink data, and determining whether to cancel the second buffer status report depending on whether the first buffer status report is a regular buffer status report or periodic buffer status report. With the proposed method, the terminal is capable of transmitting the padding BSR without extra cancellation operation, resulting in reduction terminal's operation complexity.

The invention claimed is: 
     
       1. A method for transmitting a buffer status report (BSR) by a terminal in a wireless communication system, the method comprising:
 determining that a BSR is triggered; 
 generating a medium access control (MAC) protocol data unit (PDU) for transmission including the BSR, by canceling an all triggered BSRs if the BSR is a regular BSR or a periodic BSR; and 
 transmitting, to a base station, the MAC PDU including the BSR, 
 wherein the all triggered BSRs are not canceled if the BSR is a padding BSR. 
 
     
     
       2. A terminal for transmitting a buffer status report (BSR) in a wireless communication system, the terminal comprising:
 a transceiver configured to transmit and receive signals; and 
 a controller coupled with the transceiver and configured to: 
 determine that a BSR is triggered; 
 generate a medium access control (MAC) protocol data unit (PDU) for transmission including the BSR, by canceling an all triggered BSRs if the BSR is a regular BSR or a periodic BSR; and 
 control the transceiver to transmit, to a base station, the MAC PDU including the BSR, 
 wherein the all triggered BSRs are not canceled if the BSR is a padding BSR. 
 
     
     
       3. The method of  claim 1 , wherein the padding BSR is included in the MAC PDU, when padding bits for filling a space remained are equal to or greater than a sum of a size of a BSR control element and a subheader of the BSR control element. 
     
     
       4. The method of  claim 1 , further comprising starting, after the generating of the MAC PDU, a timer for transmitting a BSR periodically or retransmitting a BSR. 
     
     
       5. The method of  claim 1 , wherein the BSR included in the MAC PDU is control information for reporting a buffered data amount to be transmitted per logical channel group. 
     
     
       6. The method of  claim 1 , wherein the BSR included in the MAC PDU logs a status of a buffer remaining after mapping data to be transmitted to an uplink resource if the uplink resource for new data can carry one uplink data, and logs the status of the buffer remained if the uplink resource for the new data is used for transmitting plural uplink data transmitted at a subframe. 
     
     
       7. The terminal of  claim 2 , wherein the padding BSR is included in the MAC PDU, when padding bits for filling a space remained are equal to or greater than a sum of a size of a BSR control element and a subheader of the BSR control element. 
     
     
       8. The terminal of  claim 2 , wherein the controller is further configured to start, after the generating of the MAC PDU, a timer for transmitting a BSR periodically or retransmitting a BSR. 
     
     
       9. The terminal of  claim 2 , wherein the BSR included in the MAC PDU is control information for reporting a buffered data amount to be transmitted per logical channel group. 
     
     
       10. The terminal of  claim 2 , wherein the BSR included in the MAC PDU logs a status of a buffer remaining after mapping data to be transmitted to an uplink resource if the uplink resource for new data can carry one uplink data, and logs the status of the buffer remained if the uplink resource for the new data is used for transmitting plural uplink data transmitted at a subframe. 
     
     
       11. A method for transmitting a buffer status report (BSR) and performed by a terminal in a wireless communication system, the method comprising:
 identifying that a BSR is triggered;   generating a medium access control (MAC) protocol data unit (PDU) including a MAC control element (CE) for the BSR; and   transmitting, to a base station, the MAC PDU,   wherein all BSRs triggered prior to the BSR are cancelled, in case that the triggered BSR is a padding BSR and the MAC PDU includes a long BSR MAC CE or a short BSR MAC CE among the long BSR MAC CE, the short BSR MAC CE and a truncated BSR MAC CE.   
     
     
       12. The method of claim 11, wherein the all BSRs triggered prior to the BSR are not canceled, in case that the triggered BSR is the padding BSR and the MAC PDU includes the truncated BSR MAC CE. 
     
     
       13. The method of claim 12, wherein the padding BSR is triggered in case that a number of padding bits is equal to or larger than a sum of a size of the MAC CE and a size of a subheader for the MAC CE. 
     
     
       14. The method of claim 13, wherein the MAC CE included in the MAC PDU is the truncated BSR MAC CE, in case that following conditions are satisfied:
 the number of padding bits is equal to or larger than a sum of a size of the short BSR MAC CE and a subheader for the short BSR MAC CE and is smaller than a sum of a size of the long BSR MAC CE and a subheader for the long BSR MAC CE; and   more than one logical channel group (LCG) has data available for transmission.   
     
     
       15. The method of claim 11, further comprising:
 starting, after generating the MAC CE, a timer for periodically transmitting a BSR; and   starting, after generating the MAC CE, a timer for retransmitting a BSR.   
     
     
       16. A terminal for transmitting a buffer status report (BSR) in a wireless communication system, the terminal comprising:
 a transceiver configured to transmit and receive a signal; and   a controller coupled with the transceiver and configured to:
 identify that a BSR is triggered, 
 generate a medium access control (MAC) protocol data unit (PDU) including a MAC control element (CE) for the BSR, and 
 transmit, to a base station, the MAC PDU, 
   wherein all BSRs triggered prior to the BSR are cancelled, in case that the triggered BSR is a padding BSR and the MAC PDU includes a long BSR MAC CE or a short BSR MAC CE among the long BSR MAC CE, the short BSR MAC CE and a truncated BSR MAC CE.   
     
     
       17. The terminal of claim 16, wherein the all BSRs triggered prior to the BSR are not canceled, in case that the triggered BSR is the padding BSR and the MAC PDU includes the truncated BSR MAC CE. 
     
     
       18. The terminal of claim 17, wherein the padding BSR is triggered, in case that a number of padding bits is equal to or larger than a sum of a size of the MAC CE and a size of a subheader for the MAC CE. 
     
     
       19. The terminal of claim 18, wherein the MAC CE included in the MAC PDU is the truncated BSR MAC CE, in case that following conditions are satisfied:
 the number of padding bits is equal to or larger than a sum of a size of the short BSR MAC CE and a subheader for the short BSR MAC CE and is smaller than a sum of a size of the long BSR MAC CE and a subheader for the long BSR MAC CE; and   more than one logical channel group (LCG) has data available for transmission.   
     
     
       20. The terminal of claim 16, wherein the controller is further configured to:
 start, after generating the MAC CE, a timer for periodically transmitting a BSR, and   start, after generating the MAC CE, a timer for retransmitting a BSR.