| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- Hokfelt, Johan, et al.
(författare)
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Interleaver structures for turbo codes with reduced storage memory requirement
- 1999
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Ingår i: Proc. IEEE Vehicular Technology Conference. - 0780354354 ; 3, s. 1585-1589
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Konferensbidrag (refereegranskat)abstract
- This paper describes two interleaver structures that reduce the memory requirement for the storage of interleaver rules. The first structure offers memory reductions of more than 50%, compared to storing the entire interleaver vector. The second structure is useful when a range of interleaver sizes are to be stored, offering memory reductions asymptotically approaching 50%. By combining the two structures, a total memory reduction of approximately 75% is achieved. This is obtained without any significant reduction of the error correcting performance of the codes
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| 5. |
- Hokfelt, Johan, et al.
(författare)
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Turbo codes: Correlated extrinsic information and its impact on iterative decoding performance
- 1999
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Ingår i: Proc. IEEE Vehicular Technology Conference. - 0780355652 ; 3, s. 1871-1875
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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. The performance of iterative decoding depends on the quality of the extrinsic inputs; badly correlated extrinsic inputs can deteriorate the performance. While most turbo coding literature assumes that the extrinsic information is uncorrelated, we investigate these correlation properties. An iterative decoding suitability measure is presented, intended to serve as an indication on the degree of correlation between extrinsic inputs. The suitability measure can be used as a complement to the weight distribution when ranking interleavers
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| 6. |
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| 7. |
- Leanderson, Carl Fredrik, et al.
(författare)
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On the performance of turbo codes and convolutional codes of low rate
- 1999
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Ingår i: Proc. IEEE Vehicular Technology Conference. - 0780354354 ; 3, s. 1560-1564
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Konferensbidrag (refereegranskat)abstract
- Recently two new classes of low-rate codes have been presented. The first class is the super-orthogonal turbo codes (SOTCs) and the second is the maximum free distance (MFD) convolutional codes. In this paper we present an evaluation of the performance vs. arithmetic decoding complexity for these codes and compare them with the previously reported super-orthogonal convolutional codes (SOCCs). For all classes of codes, the arithmetic decoding complexity is estimated, and the error performance on the additive white Gaussian noise channel is simulated. The SOCCs offer performance comparable to that of the MFD codes. However, the existence of good SOCCs is restricted to a small number of rates while the MFD codes give high performance for a multitude of rates. For the parameters used in this investigation the SOTCs yield higher performance at lower arithmetic decoding complexity than the MFD codes
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