Systems and methods for adaptive hybrid automatic retransmission requests
View Patent ↗A turbo coded hybrid ARQ with both IR and repetition existing in one or more transmission blocks is designed. The mixed combining is performed at the receiver—Chase combining is performed for the repetitions first, followed by code combining for all code bits based on Chase combining outputs. The packet error probability is obtained by applying the union-Bhattacharyya (UB) bound for parallel channels. The throughput optimization of hybrid ARQ is determined as well as the optimal assignment rates by solving the optimization using a genetic algorithm.
1. A method of packet transmission in an adaptive hybrid automatic repeat request wireless transmission system with incremental redundancy comprising:
determining an optimized assignment rate for a packet based at least in part on a maximal number of transmission attempts and a long term signal to noise ration of the wireless transmission system;
determining an optimized modulation set for the packet based at least in part on the maximal number of transmission attempts and the long term signal to noise ration of the wireless transmission system;
transmitting information related to the packet based at least in part on the determined optimized assignment rate and determined optimized modulation set; and
decoding the information by performing mixed combining for one or more transmission blocks at a receiver.
2. The method of claim 1 wherein determining an optimized modulation set for the packet based at least in part on the maximal number of transmission attempts and the long term signal to noise ration of the wireless transmission system and transmitting information related to the packet based at least in part on the determined optimized assignment rate and determined optimized modulation set comprises:
determining one or more integer parts of one or more transmission blocks;
determining one or more residue parts of the one or more transmission blocks;
modulating a plurality of copies of a mother codeword;
grouping a plurality of bits of the mother codeword into a first set and a second set;
determining a modulation set; and
combining a plurality of symbols in the modulation set into a single sequence.
3. The method of claim 2 further comprising:
obtaining an assignment rate of transmission; and
wherein determining the one or more integer parts of the one or more transmission blocks and determining the one or more residue parts of the one or more transmission blocks is based at least in part on the obtained assignment rate of transmission.
4. The method of claim 2 wherein modulating the plurality of copies of a mother codeword comprises:
modulating a plurality of copies of a mother codeword that is equal to a number of the one or more integer parts of the one or more transmission blocks.
5. The method of claim 4 wherein modulating the plurality of copies of a mother codeword comprises:
modulating the plurality of copies of the mother codeword into a plurality of symbols.
6. The method of claim 2 wherein determining the modulation set comprises:
modulating the modulation set into a plurality of symbols.
7. The method of claim 2 further comprising:
transmitting the single sequence.
8. The method of claim 1 wherein transmitting information related to the packet based at least in part on the determined optimized assignment rate and determined optimized modulation set comprises:
(a) encoding an information sequence with a turbo code to form a codeword;
(b) configuring a hybrid automatic repeat request method;
(c) determining an optimal assignment rate;
(d) determining a modulation set;
(e) modulating the codeword into a first plurality of symbols;
(f) modulating a portion of the codeword into a second plurality of symbols;
(g) combining the first plurality of modulated symbols and the second plurality of modulated symbols into a sequence; and
(h) transmitting the sequence.
9. The method of claim 8 wherein configuring the hybrid automatic repeat request method comprises:
determining a maximum number of transmissions; and
determining a long-term signal to noise ratio P.
10. The method of claim 8 wherein determining the optimal assignment rate and determining the modulation set comprises retrieving the optimal assignment rate and determining the modulation set from a memory.
11. The method of claim 8 wherein determining the optimal assignment rate and determining the modulation set comprises retrieving the optimal assignment rate and determining the modulation set from a table.
12. The method of claim 8 wherein modulating the codeword comprises:
modulating a plurality of copies of the codeword;
grouping a plurality of bits of the codeword into a first set and a second set; and
modulating a plurality of bits of the first set into a plurality of symbols.
13. The method of claim 8 further comprising:
determining if a negative acknowledgement is received;
if a negative acknowledgement is received, determining if a maximum number of transmissions have been sent; and
if the maximum number of transmissions has not been sent, iteratively performing steps (e)-(h).
14. The method of claim 8 further comprising:
determining if an acknowledgement is received;
if an acknowledgement has not been received, determining if a maximum number of transmissions have been sent; and
if the maximum number of transmissions has not been sent, iteratively performing steps (e)-(h).
15. The method of claim 1 wherein decoding the information by performing mixed combining for one or more transmission blocks at the receiver comprises:
performing Chase combining on an intra-block portion of a received transmission block;
performing Chase combining on an inter-block portion of the received transmission block; and
jointly decoding both the intra-block portion and the inter-block portion as one turbo codeword.
16. The method of claim 15 wherein performing Chase combining on an intra-block portion of a received transmission block comprises:
performing pre-demodulation maximum ratio combining on symbol repetitions of the received transmission block; and
performing pre-demodulation Chase combining for a first portion of a codeword and a second portion of the codeword.
17. The method of claim 15 wherein performing Chase combining on an inter-block portion of the received transmission block comprises:
maximum ratio combining the inter-block portion of the received transmission block.
18. The method of claim 15 wherein jointly decoding both the intra-block portion and the inter-block portion as one turbo codeword comprises:
decoding the received transmission block in one decoder using Chase combining and demodulation outputs.