| 1. |
- Blad, Anton, et al.
(författare)
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Integer linear programming based optimization of puncturing sequences for quasi-cyclic low-density parity-check codes
- 2010
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Ingår i: Proceedings of International Symposium on Turbo Codes and Iterative Information Processing. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- An optimization algorithm for the design of puncturing patterns for low-density parity-check codes is proposed. The algorithm is applied to the base matrix of a quasi-cyclic code, and is expanded for each block size used. Thus, storing puncturing patterns specific to each block size is not required. Using the optimization algorithm, the number of 1-step recoverable nodes in the base matrix is maximized. The obtained sequence is then used as a base to obtain longer puncturing sequences by a sequential increase of the allowed recovery delay. The proposed algorithm is compared to one previous greedy algorithm, and shows superior performance for high rates when the heuristics are applied to the base matrix in order to create block size-independent puncturing patterns.
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| 2. |
- Blad, Anton, et al.
(författare)
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Rate-compatible LDPC code decoder using check-node merging
- 2010
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Ingår i: Proceedings of Asilomar Conference on Signals, Systems and Computers. - : IEEE. - 9781424497225 ; , s. 1119-1123
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Konferensbidrag (refereegranskat)abstract
- The use of rate-compatible error correcting codes offers several advantages as compared to the use of fixed-rate codes: a smooth adaptation to the channel conditions, the possibility of incremental Hybrid ARQ schemes, as well as sharing of the encoder and decoder implementations between the codes of different rates. In this paper, the implementation of a decoder for rate-compatible quasi-cyclic LDPC codes is considered. Assuming the use of a code ensemble obtained through puncturing of a low-rate mother code, the decoder achieves significantly reduced convergence rates by merging the check node neighbours of the punctured variable nodes. The architecture uses the min-sum algorithm with serial node processing elements to efficiently handle the wide spread of node degrees that results from the merging of the check nodes.
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| 3. |
- Cao, CongZhe, et al.
(författare)
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An extended packetization-aware mapping algorithm for scalable video coding in finite-length fountain codes
- 2013
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Ingår i: Science China Information Sciences. - : Springer Science and Business Media LLC. - 1674-733X .- 1869-1919. ; 56:4, s. 042311-
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Tidskriftsartikel (refereegranskat)abstract
- We propose an extended packetization-aware mapping algorithm based on fountain codes to enhance video stream performance which is vulnerable to packet losses. By properly utilizing the proposed algorithm in finite-length cases, the edges connecting to a source symbol are scattered over multiple encoding packets so that the decoding probabilities are increased. Furthermore, an improved degree distribution is designed to obtain better decoding probabilities. Numerical results, it is confirmed that the proposed algorithm in finite-length cases can augment decoding probabilities and the improved degree distribution can increase peak signal-to-noise ratio (PSNR) of scalable video coding (SVC) in a hostile communication environment.
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| 4. |
- ChengWen, Xing, et al.
(författare)
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Statistically robust resource allocation for distributed multi-carrier cooperative networks
- 2013
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Ingår i: Science China Information Sciences. - : Springer. - 1674-733X .- 1869-1919. ; 56:2, s. 109-121
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate joint subcarrier and power allocation scheme for distributed multi-carrier cooperative networks with imperfect channel state information. Using practical channel estimation algorithms, the statistic model of the channel estimation error is first derived. Then based on the channel error model, the resource allocation scheme aims at maximizing the sum rate of the overall network. Specifically, both subcarrier allocation and power allocation are taken into account. In the subcarrier allocation, a realistic problem of the power leakage between neighboring subcarriers is also addressed. Furthermore, based on Lagrange dual-decomposition algorithm, a practical power allocation algorithm is proposed. Finally, the simulation results demonstrate the performance advantages of the proposed robust design.
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| 5. |
- Fei, Zesong, et al.
(författare)
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Improved Luby transform codes in low overhead regions for binary erasure channels
- 2014
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Ingår i: Transaction on Emerging Telecommunications Technologies. - : Wiley-Blackwell. - 2161-3915.
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Tidskriftsartikel (refereegranskat)abstract
- We study improved degree distribution for Luby transform (LT) codes, which exhibits improved bit error rates particularly in low overhead regions. We construct the degree distribution by modifying robust soliton distribution. The performance of our proposed LT codes is evaluated and compared with the conventional LT codes via And-Or tree analysis. Then we propose a transmission scheme based on our proposed degree distribution to improve the frame error rate in full recovery regions. Furthermore, the improved degree distribution is applied to distributed multi-source relay networks and unequal error protection. It is shown that our schemes achieve better performance and reduced complexity especially in low overhead regions, compared with conventional schemes.
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| 6. |
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| 7. |
- Huang, Jingxuan, et al.
(författare)
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Design and Analysis of Online Fountain Codes for Intermediate Performance
- 2020
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Ingår i: IEEE Transactions on Communications. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0090-6778 .- 1558-0857. ; 68:9, s. 5313-5325
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Tidskriftsartikel (refereegranskat)abstract
- For the benefit of improved intermediate performance, recently online fountain codes attract much research attention. However, there is a trade-off between the intermediate performance and the full recovery overhead for online fountain codes, which prevents them to be improved simultaneously. We analyze this trade-off, and propose to improve both of these two performance. We first propose a method called Online Fountain Codes without Build-up phase (OFCNB) where the degree-1 coded symbols are transmitted at first and the build-up phase is removed to improve the intermediate performance. Then we analyze the performance of OFCNB theoretically. Motivated by the analysis results, we propose Systematic Online Fountain Codes (SOFC) to further reduce the full recovery overhead. Theoretical analysis shows that SOFC has better intermediate performance, and it also requires lower full recovery overhead when the channel erasure rate is lower than a constant. Simulation results verify the analysis and demonstrate the superior performance of OFCNB and SOFC in comparison to other online fountain codes.
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| 8. |
- Huang, Jingxuan, et al.
(författare)
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Performance Analysis and Improvement of Online Fountain Codes
- 2018
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Ingår i: IEEE Transactions on Communications. - : IEEE. - 0090-6778 .- 1558-0857. ; 66:12, s. 5916-5926
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Tidskriftsartikel (refereegranskat)abstract
- The online property of fountain codes enables the encoder to efficiently find the optimal encoding strategy that minimizes the encoding overhead based on the instantaneous decoding state. Therefore, the receiver is able to optimally recover data from losses that differ significantly from the initial expectation. In this paper, we propose a framework to analyze the relationship between overhead and the number of recovered source symbols for online fountain codes based on random graph theory. Motivated by the analysis, we propose improved online fountain codes (IOFCs) by introducing a designated selection of source symbols. Theoretical analysis shows that IOFC has lower overhead compared with the conventional online fountain codes. We verify the proposed analysis via simulation results and demonstrate the tradeoff between full recovery and intermediate performance in comparison to other online fountain codes.
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| 9. |
- Huang, Jingxuan, et al.
(författare)
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Reliable Broadcast Based on Online Fountain Codes
- 2021
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Ingår i: IEEE Communications Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1089-7798 .- 1558-2558. ; 25:2, s. 369-373
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we study wireless broadcast schemes based on online fountain codes. We first propose and analyze an online fountain code based-broadcast scheme, where the coded symbol degree is updated based on the decoding states of all receivers. Then we propose and analyze an improved broadcast scheme by taking advantage of the received coded symbols that are not immediately decodable. Simulation results demonstrate that our proposed scheme has better performance compared to other broadcast schemes based on feedback fountain codes.
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| 10. |
- Huang, Jingxuan, et al.
(författare)
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Weighted Online Fountain Codes With Limited Buffer Size and Feedback Transmissions
- 2021
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Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 69:12, s. 7960-7973
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Tidskriftsartikel (refereegranskat)abstract
- Online fountain codes (OFC) have attracted much attention for their good intermediate performance, which is important for receivers with low-complexity requirement. However, low-complexity receivers generally have limited buffer size to store coded symbols that have not been fully decoded yet, as well as limited power budget for feedback transmissions. In this paper, we propose improved transmission schemes for online fountain codes to reduce the buffer occupancy and feedback transmissions. Firstly, we analyze the relationship between buffer occupancy and overhead as well as the relationship between recovery rate and overhead for online fountain codes. Motivated by the analysis, we propose the weighted online fountain codes (WOFC) which can adapt to various buffer sizes by adjusting the weight to control the probability that a coded symbol can be fully processed immediately, and analyze its performance. Then we further propose weighted online fountain codes with low feedback (WOFC-LF), which utilize the proposed analysis to estimate the recovery rate, and reduce feedback transmissions. Simulation results verify the effectiveness of the analysis for both OFC and WOFC, and demonstrate the superior performance of WOFC-LF with limited buffer size and feedback transmissions.
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