| 1. |
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| 2. |
- Handlery, Marc, et al.
(författare)
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Some distance properties of tailbiting codes
- 2001
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Ingår i: [Host publication title missing]. - 0780371232 ; , s. 290-290
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Konferensbidrag (refereegranskat)abstract
- The active tailbiting segment distance for convolutional codes is introduced. Together with the earlier defined active burst distance, it describes the error correcting capability of a tailbiting code encoded by a convolutional encoder. Lower bounds on the new active distance as well as an upper bound on the ratio between tailbiting length and memory of the encoder such that its minimum
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| 3. |
- Höst, Stefan, et al.
(författare)
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A distance measure tailored to tailbiting codes
- 2002
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Ingår i: Problems of Information Transmission. - 0032-9460. ; 38:4, s. 280-295
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Tidskriftsartikel (refereegranskat)abstract
- The error-correcting capability of tailbiting codes generated by convolutional encoders is described. In order to obtain a description beyond what the minimum distance d min of the tailbiting code implies, the active tailbiting segment distance is introduced. The description of correctable error patterns via active distances leads to an upper bound on the decoding block error probability of tailbiting codes. The necessary length of a tailbiting code so that its minimum distance is equal to the free distance d free of the convolutional code encoded by the same encoder is easily obtained from the active tailbiting segment distance. This is useful when designing and analyzing concatenated convolutional codes with component codes that are terminated using the tailbiting method. Lower bounds on the active tailbiting segment distance and an upper bound on the ratio between the tailbiting length and memory of the convolutional generator matrix such that d min equals d free are derived. Furthermore, affine lower bounds on the active tailbiting segment distance suggest that good tailbiting codes are generated by convolutional encoders with large active-distance slopes.
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| 4. |
- Höst, Stefan, et al.
(författare)
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On coded OFDM over frequency selective channels using woven convolutional codes
- 2003
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Ingår i: Proceedings 2003 IEEE International Symposium on Information Theory. ISIT 2003 (Cat. No.03CH37432). - 0780377281 ; , s. 36-36
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Konferensbidrag (refereegranskat)abstract
- A communication system with woven convolutional codes and OFDM is considered. With coherent reception and iterative decoding this combination seems promising over frequency selective channels. The robustness of the considered class of schemes is illustrated by simulation results for specific fixed channel transfer functions and AWGN
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| 5. |
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| 6. |
- Höst, Stefan, et al.
(författare)
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Woven convolutional codes I: Encoder properties
- 2002
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Ingår i: IEEE Transactions on Information Theory. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9448. ; 48:1, s. 149-161
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Tidskriftsartikel (refereegranskat)abstract
- Encoders for convolutional codes with large free distances can be constructed by combining several less powerful convolutional encoders. This paper is devoted to constructions in which the constituent convolutional codes are woven together in a manner that resembles the structure of a fabric. The general construction is called twill and it is described together with two special cases, viz., woven convolutional encoders with outer warp and with inner warp. The woven convolutional encoders inherit many of their structural properties, such as minimality and catastrophicity, from their constituent encoders. For all three types of woven convolutional codes upper and lower bounds on their free distances as well as lower bounds on the active distances of their encoders are derived.
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| 7. |
- Jordan, Ralph, et al.
(författare)
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Decoding of woven convolutional codes and simulation results
- 2000
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Ingår i: [Host publication title missing]. - 0780358570 ; , s. 96-96
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Konferensbidrag (refereegranskat)abstract
- An iterative decoding scheme for woven convolutional codes is presented. It is called pipeline decoding and operates in a window sliding over the received sequence. This exploits the nature of convolutional codes as sequences and suits the concept of convolutional encoding and decoding as a continuous process. The pipeline decoder is analyzed in terms of decoding delay and decoding complexity. Additional interleaving for woven convolutional constructions is introduced by employing a convolutional scrambler. It is shown that some types of interleaving preserve the lower bound on the free distance of the original woven construction. Simulation results for woven convolutional codes are presented
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| 8. |
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| 9. |
- Jordan, R, et al.
(författare)
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Woven convolutional codes II: Decoding aspects
- 2004
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 50:10, s. 2522-2529
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Tidskriftsartikel (refereegranskat)abstract
- An iterative decoding scheme for woven convolutional codes is presented. It operates in a window sliding over the received sequence. This exploits the nature of convolutional codewords as infinite sequences and reflects the concept of considering convolutional encoding and decoding as a continuous process. The decoder is analyzed in terms of decoding delay and decoding complexity. Its basic building block is a symbol-by-symbol a posteriori probability (APP) decoder for convolutional codes, which is a windowed variant of the well-known Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm. Additional interleaving for the woven constructions is introduced by employing convolutional scramblers. It is shown that row-wise random interleaving preserves the lower bound on the free distance of the original woven constructions. Based on the properties of the interleavers, new lower bounds on the free distance of woven constructions with both outer warp and inner warp are derived. Simulation results for woven convolutional codes with and without additional interleaving are presented.
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| 10. |
- Strandh, Magnus, et al.
(författare)
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On robustness of turbo coded OFDM systems over frequency selective channels
- 2003
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Ingår i: 8th International OFDM-Workshop.
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Konferensbidrag (refereegranskat)abstract
- The robustness of fixed Turbo coded communication systems over frequency selective channels are investigated. The simulated amplitude functions are based on an idealised two level function and a decaying function. The results indicate that the system can cope with severe disturbances without to much loss.
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