HARQ Buffer Size Reduction in Wireless Systems for Downlink Shared Channels
A receiver arranged to process a flow of data in a communication system for downlink shared channels and a method for processing the flow of data sequence. The receiver includes a processor that receives a subframe comprising a data packet; a demapper that receives supplemental channel data symbols and is positioned after the processor in a sequence of the flow of data; means for performing rate matching of estimated the data symbols and positioned after the demapper in the data sequence; and a Hybrid Automatic Retransmission Request (HARQ) buffer positioned before the demapper in the data sequence. The communication system includes a long-term evolution (LTE) communication system.
1 . A receiver arranged to process a flow of data in a communication system for downlink shared channels, said receiver comprising:
a processor that receives a subframe comprising a data packet;
a demapper that receives supplemental channel data symbols and is positioned after said processor in a sequence of said flow of data;
means for performing rate matching of estimated said data symbols and positioned after said demapper in the data sequence; and
a Hybrid Automatic Retransmission Request (HARQ) buffer positioned before said demapper in said data sequence.
2 . The receiver of claim 1 , wherein said supplemental channel data symbols are arranged in a transport block that is stored as Quadrature amplitude modulation (QAM) symbols in said HARQ buffer.
3 . The receiver of claim 2 , wherein said data packet is retransmitted in said data sequence, and wherein said data packet is entirely stored in said HARQ buffer.
4 . The receiver of claim 3 , further comprising:
a combiner positioned after said means for performing rate matching in said data sequence; and
a turbo decoder positioned after said combiner in said data sequence.
5 . The receiver of claim 4 , wherein the stored QAM symbols are re-demapped, combined on a log-likelihood ratio (LLR) level with all previous retransmissions of said data packet, and applied to said turbo decoder.
6 . The receiver of claim 1 , wherein said processor transmits channel state information (CSI) to said HARQ buffer.
7 . The receiver of claim 2 , wherein said QAM symbols comprise in-phase and quadrature components.
8 . The receiver of claim 1 , wherein said HARQ buffer stores only reference signals.
9 . The receiver of claim 8 , wherein said reference signals are transmitted during transmission of orthogonal frequency-division multiplexing (OFDM) symbols, wherein said reference signals are transmitted during transmission of a first and fifth OFDM symbol of each slot when a short cyclic prefix (CP) is used, wherein said reference signals are transmitted during transmission of a first and fourth OFDM symbol of each slot when a long cyclic prefix (CP) is used, and wherein said reference signals are transmitted every sixth subcarrier.
10 . The receiver of claim 1 , wherein said communication system comprises a long-term evolution (LTE) communication system.
11 . A method for processing a flow of data in a receiver in a communication system for downlink shared channels, said method comprising:
receiving a subframe comprising a data packet in a processor;
positioning a demapper that receives supplemental channel data symbols after said processor in a sequence of said flow of data;
performing rate matching of estimated said data symbols after demapping of said data symbols; and
positioning a Hybrid Automatic Retransmission Request (HARQ) buffer before said demapper in the data sequence.
12 . The method of claim 11 , wherein said supplemental channel data symbols are arranged in a transport block that is stored as Quadrature amplitude modulation (QAM) symbols in said HARQ buffer.
13 . The method of claim 12 , wherein said data packet is retransmitted in said data sequence, and wherein said data packet is entirely stored in said HARQ buffer.
14 . The method of claim 13 , further comprising:
combining code blocks after said rate matching is performed; and
decoding said code blocks after the combining occurs.
15 . The method of claim 14 , wherein the stored QAM symbols are re-demapped, combined on a log-likelihood ratio (LLR) level with all previous retransmissions of said data packet, and applied to a turbo decoder that performs said decoding.
16 . The method of claim 11 , further comprising transmitting channel state information (CSI) to said HARQ buffer.
17 . The method of claim 12 , wherein said QAM symbols comprise in-phase and quadrature components.
18 . The method of claim 11 , further comprising storing only reference signals in said HARQ buffer.
19 . The method of claim 18 , wherein said reference signals are transmitted during transmission of orthogonal frequency-division multiplexing (OFDM) symbols, wherein said reference signals are transmitted during transmission of a first and fifth OFDM symbol of each slot when a short cyclic prefix (CP) is used, wherein said reference signals are transmitted during transmission of a first and fourth OFDM symbol of each slot when a long cyclic prefix (CP) is used, and wherein said reference signals are transmitted every sixth subcarrier.
20 . The method of claim 11 , wherein said communication system comprises a long-term evolution (LTE) communication system.