| 1. |
- Uhlemann, Elisabeth, et al.
(författare)
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Optimal Incremental-redundancy strategy for type-II hybrid ARQ
- 2003
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Ingår i: ISIT 2003 Yokohama. - Piscataway, N.J. : IEEE. - 0780377281 ; , s. 448-, s. 448-
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Konferensbidrag (refereegranskat)abstract
- Given a type-II hybrid ARQ scheme, we propose a general solution to find the optimal partitioning of n-k parity bits over at most M transmissions. The solution is in terms of maximizing the average code rate for a given puncturing pattern.
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| 2. |
- Uhlemann, Elisabeth, et al.
(författare)
-
Optimal type-II concatenated hybrid ARQ using single parity check codes
- 2003
-
Ingår i: Proc. International Symposium on Turbo Codes & Related Topics, Brest, France, September 2003. ; , s. 587-590
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Konferensbidrag (refereegranskat)abstract
- We consider an incremental redundancy (IR) type-II hybrid ARQ scheme based on multidimensional single parity check (SPC) product codes. Random interleaving is applied between dimensions, resulting in equivalent systematic, parallel or serially concatenated SPC codes. This enables larger interleavers and a larger range of overall code rates. The puncturing pattern used for IR transmissions of the concatenated SPC codes is chosen specifically to reduce decoder complexity for the hybrid ARQ scheme, activating only those constituent decoders for which parity bits have been received. Given the proposed puncturing pattern and a maximum number of allowable transmissions, an approach for determining the optimal number of parity bits per IR transmission in terms of maximizing the overall code rate, is suggested. With this strategy, each data frame is accepted following the transmission of a minimum number of parity bits.
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| 3. |
- Uhlemann, Elisabeth, et al.
(författare)
-
Packet combining and doping in concatenated hybrid ARQ schemes using iterative decoding
- 2003
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Ingår i: The IEEE Wireless Communications and Networking, 2003. WCNC 2003. 2003 IEEE. - Piscataway, NJ : IEEE. - 0780377001 ; , s. 849-854
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Konferensbidrag (refereegranskat)abstract
- We consider serially concatenated block codes in a hybrid ARQ scheme using iterative decoding. The extrinsic information generated in the iterative decoding process is saved and used when a retransmission is decoded. Two different strategies are examined; one using the extrinsic information only in the very first iteration, whereas the other uses it in all subsequent iterations until another retransmission arrives. The latter can be seen as turbo or concatenated code combining whereas the former, where the extrinsic information is used only once may be seen as code doping, providing an alternative perspective. The strategy of saving the extrinsic information is also compared to traditional type-III, equal gain diversity combining. Using the extrinsic information from previous retransmission is shown to improve performance not only in terms of bit error rate but also in terms of throughput and convergence speed and requires only negligible additional decoder complexity. The performance of this strategy is however not as good as simple equal gain combining. As a consequence, the investigated schemes are not competitive alternatives, however, the code doping procedure can be used in conjunction with traditional diversity combining schemes, improving further on convergence speed.
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