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| 2. |
- Henriksson, Anders, et al.
(författare)
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Evaluation of trellis termination strategy for turbo codes in UMTS
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This input document proposes a trellis termination startegy for turbo codes in UMTS. The proposal is based upon the fact that the extrinsic information used in the decoding of turbo codes mitigates the effect of a truncated trellis, and that this mitigating effect can be enhanced by imposing certain restrictions on the interleaver design. The simulation parameters used in the comparison bewteen different methods complies with the parameters described in Tdoc SMG2 UMTS-L1 385/98, except in one point: they are not restricted to the reference pseudo-random interleaver provided by HNS. The reason for this is the close interaction between interleaver design and trellis termination. We recommend that the choice of trellis termination method and interleaver design should be done together, and not as separate optimizations.
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| 3. |
- Henriksson, Anders, et al.
(författare)
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Interleaver design for turbo codes with reduced memory requitement
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The interleaving and deinterleaving performed in turbo codes require that the interleaver rule is either stored in memory or that it can be calculated in real time. For large interleavers, and for systems where many different interleaver sizes are used, the interleaver rule storage becomes memory demanding. This input document presents and evaluates two interleaver structures that reduce the required storage area. Each structure offer memory savings of approximately 50%, and since they can be combined, a total saving of approximately 75% is achievable. Simulation results show that these savings are achieved without a significant degradation of the performance of the turbo codes.
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| 4. |
- Hokfelt, Johan, et al.
(författare)
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A comparison of turbo codes using different trellis terminations
- 2001
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Ingår i: Annales des Télécommunications. - 1958-9395. ; 56:7-8, s. 379-383
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined This paper investigates the incidence of trellis termination on the performance of turbo codes and accounts for the performance degradation often experienced in the absence of trellis termination. Analytical upper bounds on the performance for the ensemble of turbo codes using different trellis termination strategies as well as performance results obtained by computer simulation are presented. In the case of uniform interleaving, the performance differences between various termination methods are relatively small, except when using no trellis termination at all.
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| 5. |
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| 6. |
- Hokfelt, Johan, et al.
(författare)
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A survey on trellis termination alternatives for turbo codes
- 1999
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Ingår i: Proc. IEEE Vehicular Technology Conference. - 0780355652 ; 3, s. 2225-2229
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Konferensbidrag (refereegranskat)abstract
- Numerous strategies and methods for trellis termination of turbo codes have been presented and proposed in the literature. In this paper the most common trellis termination methods are compared and their relative performances are investigated. An important observation is that the performance of a termination method is highly dependent on the particular interleaver choice. Conclusions should thus be drawn for the combination of interleaver and termination method, and not for the termination method alone. Another important conclusion is that the particular choice of termination method is not crucial for the error correcting performance, as long as certain precautions are taken regarding the choice of interleaver
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| 7. |
- Hokfelt, Johan, et al.
(författare)
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A Turbo Code Interleaver Design Criterion Based on the Performance of Iterative Decoding
- 2001
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Ingår i: IEEE Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1089-7798. ; 5:2, s. 52-54
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Tidskriftsartikel (refereegranskat)abstract
- The performance of a turbo code is dependent on two code properties: its distance spectrum and its suitability to be iteratively decoded. Both these properties are influenced by the choice of interleaver used in the turbo encoder. This paper presents an interleaver design criterion that focuses on the performance of iterative decoding, based on the correlation properties of the extrinsic inputs. Interleavers designed with the proposed criterion achieve very competitive performances, both in terms of convergence rates and error correcting capabilities
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| 8. |
- Hokfelt, Johan, et al.
(författare)
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Assessing interleaver suitability for turbo codes
- 1998
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Ingår i: Proc. Nordic Radio Symposium.
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Konferensbidrag (refereegranskat)abstract
- The two major purposes of the interleaver in a turbo coding scheme are, firstly, to improve the weight distribution of the turbo code, and, secondly, to make the performance of iterative decoding as close to maximum likelihood as possible. Both these purposes should be considered when ranking and designing interleavers for turbo codes. In lack of a measure of how well the second purpose is carried out we investigate a method to assess the iterative decoding suitability of interleavers. This suitability measure is used as a complement to the weight distribution, which is an insufficient base for ranking interleavers when iterative decoding is employed. It is exemplified that with proper consideration of both interleaver tasks it is possible to single out interleaver designs which yield turbo codes with improved bit and frame error rate performances, compared to a number of other interleaver designs.
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| 9. |
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| 10. |
- Hokfelt, Johan, et al.
(författare)
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Interleaver design for turbo codes based on the performance ofiterative decoding
- 1999
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Ingår i: Proc. IEEE International Conference on Communications. - 078035284X ; 1, s. 93-97
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Konferensbidrag (refereegranskat)abstract
- The performance of a turbo code is dependent on two properties of the code: its distance spectrum and its suitability to be iteratively decoded. Both these properties are dependent on the specific interleaver used in the turbo-coding scheme. This paper describes a strategy for interleaver design that includes a criterion for the performance of iterative decoding. This criterion is based upon correlation properties of the extrinsic information, which is used as a priori inputs to the constituent decoders. Simulations comparing interleaver choices indicate an improved turbo code performance for interleavers designed with algorithms including a correlation criterion
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