Method of transmitting data using harq

Abstract

A method is provided for performing data transmission using a hybrid automatic repeat request (HARQ) scheme performed by a transmitter. The transmitter transmits uplink data to a receiver, and receives an acknowledgement (ACK) signal for the data from the receiver. The transmitter determines whether or not an uplink grant associated with the ACK signal is received. The transmitter keeps the uplink data in an HARQ buffer of the transmitter without flushing the uplink data if it is determined that the uplink grant associated with the ACK signal is not received within a certain time period from the receiver.

What is claimed is: 
     
         1 . A method of data transmission using a hybrid automatic repeat request (HARQ) scheme performed by a transmitter, the method comprising:
 transmitting uplink data to a receiver;   receiving an acknowledgement (ACK) signal for the data from the receiver; and   determining whether or not an uplink grant associated with the ACK signal is received, wherein the transmitter keeps the uplink data in an HARQ buffer of the transmitter without flushing the uplink data if it is determined that the uplink grant associated with the ACK signal is not received within a certain time period from the receiver.   
     
     
         2 . The method of  claim 1 , further comprising:
 after receiving the uplink grant, retransmitting the uplink data based on a radio resource indicated by the uplink grant.   
     
     
         3 . The method of  claim 1 , wherein if retransmission is requested, the transmitter determines whether a measurement gap exists at retransmission time, and
 wherein a number of current transmissions is incremented by one if the retransmission is requested.   
     
     
         4 . The method of  claim 1 , wherein the uplink grant is transmitted on a physical downlink control channel (PDCCH). 
     
     
         5 . The method of  claim 1 , wherein the uplink data is a medium access control protocol data unit (MAC PDU). 
     
     
         6 . The method of  claim 1 , wherein the uplink grant comprises a new data indicator (NDI), the NDI indicating retransmission. 
     
     
         7 . The method of  claim 1 , wherein if the uplink grant is received, an incremental redundancy version is set as indicated by the uplink grant. 
     
     
         8 . The method of  claim 1 , further comprising:
 flushing the HARQ buffer if the number of current transmissions is determined to be equal to a maximum number of transmissions of the uplink data.   
     
     
         9 . The method of  claim 8 , further comprising:
 setting the maximum number of transmissions for all logical channels and HARQ processes.   
     
     
         10 . The method of  claim 1 , wherein the certain time period is a transmission time interval (TTI). 
     
     
         11 . A transmitter for data transmission using a hybrid automatic repeat request (HARQ) scheme, the transmitter comprising:
 a radio unit configured to transmit and receive a radio signal; and   a processor coupled to the radio unit,   wherein the processor is configured to:
 transmit uplink data to a receiver; 
 receive an acknowledgement (ACK) signal for the data from the receiver; 
 determine whether or not an uplink grant associated with the ACK signal is received; and 
 keep the uplink data in an HARQ buffer of the transmitter without flushing the uplink data if it is determined that the uplink grant associated with the ACK signal is not received within a certain time period from the receiver. 
   
     
     
         12 . The transmitter of  claim 11 , wherein the processor is further configured to:
 after receiving the uplink grant, retransmit the uplink data based on a radio resource indicated by the uplink grant.   
     
     
         13 . The transmitter of  claim 11 , wherein if retransmission is requested, the processor determines whether a measurement gap exists at retransmission time, and
 wherein a number of current transmissions is incremented by one if the retransmission is requested.   
     
     
         14 . The transmitter of  claim 11 , wherein the uplink grant is transmitted on a physical downlink control channel (PDCCH). 
     
     
         15 . The transmitter of  claim 11 , wherein the uplink data is a medium access control protocol data unit (MAC PDU). 
     
     
         16 . The transmitter of  claim 11 , wherein the uplink grant comprises a new data indicator (NDI), the NDI indicating retransmission. 
     
     
         17 . The transmitter of  claim 11 , wherein if the uplink grant is received, an incremental redundancy version is set as indicated by the uplink grant. 
     
     
         18 . The transmitter of  claim 11 , wherein the processor is further configured to flush the HARQ buffer if the number of current transmissions becomes equal to a maximum number of transmissions of the data. 
     
     
         19 . The transmitter of  claim 18 , wherein the processor is further configured to set the maximum number of transmissions that is applied to all logical channels and HARQ processes. 
     
     
         20 . The transmitter of  claim 11 , wherein the certain time period is a transmission time interval (TTI).