Reliability-based hybrid automatic repeat request(HARQ)(RB-HARQ)is a recently developedform of incremental-redundancy ARQ.It achieves good performance whereas large retransmission requestpackets should be fed back.In ...Reliability-based hybrid automatic repeat request(HARQ)(RB-HARQ)is a recently developedform of incremental-redundancy ARQ.It achieves good performance whereas large retransmission requestpackets should be fed back.In this paper,in order to reduce the number of the fed back bits,we pro-pose a HARQ scheme applied in time duplex division orthogonal frequency division multiplexing(TDD-OFDM)system over the slow fading channel which is named channel-based HARQ(CB-HARQ).Be-cause one bit which meets deep fading is always with small value of log likelihood ratio(LLR)during theprocess of decoding of LDPC code,the bits transmitted on the carrier with deep fading are retransmitted.At the receiver,the decoder will compute the locations of retransmission bits according to the channelfading values which are gotten by utilizing the feature of channel symmetry in TDD mode.So the indicesof retransmission bits are avoided to be transmitted.Simulation results show that this method achievesbetter BER performance and requires much smaller request packets in feedback link.展开更多
基金the National High Technology Research and Development Programme of China(No.2003AA12331004)
文摘Reliability-based hybrid automatic repeat request(HARQ)(RB-HARQ)is a recently developedform of incremental-redundancy ARQ.It achieves good performance whereas large retransmission requestpackets should be fed back.In this paper,in order to reduce the number of the fed back bits,we pro-pose a HARQ scheme applied in time duplex division orthogonal frequency division multiplexing(TDD-OFDM)system over the slow fading channel which is named channel-based HARQ(CB-HARQ).Be-cause one bit which meets deep fading is always with small value of log likelihood ratio(LLR)during theprocess of decoding of LDPC code,the bits transmitted on the carrier with deep fading are retransmitted.At the receiver,the decoder will compute the locations of retransmission bits according to the channelfading values which are gotten by utilizing the feature of channel symmetry in TDD mode.So the indicesof retransmission bits are avoided to be transmitted.Simulation results show that this method achievesbetter BER performance and requires much smaller request packets in feedback link.
