| 1. |
- Cedervall, Mats, et al.
(författare)
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A fast algorithm for computing distance spectrum of convolutional codes
- 1989
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Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778. ; 35:6, s. 1146-1159
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Tidskriftsartikel (refereegranskat)abstract
- New rate-compatible convolutional (RCC) codes with high constraint lengths and a wide range of code rates are presented. These new codes originate from rate 1/4 optimum distance spectrum (ODS) convolutional parent encoders with constraint lengths 7-10. Low rate encoders (rates 115 down to 1/10) are found by a nested search, and high rate encoders (rates above 1/4) are found by rate-compatible puncturing. The new codes form rate-compatible code families more powerful and flexible than those previously presented. It is shown that these codes are almost as good as the existing optimum convolutional codes of the same fates. The effects of varying the design parameters of the rate-compatible punctured convolutional (RCPC) codes, i.e., the parent encoder rate, the puncturing period, and the constraint length, are also examined. The new codes are then applied to a multicode direct-sequence code-division multiple-access (DS-CDMA) system and are shown to provide good performance and rate-matching capabilities. The results, which are evaluated in terms of the efficiency for Gaussian and Rayleigh fading channels, show that the system efficiency increases with decreasing code rate
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| 2. |
- Johannesson, Rolf, et al.
(författare)
-
On sequential decoding for the Gilbert channel
- 1988
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Ingår i: IEEE Transactions on Information Theory. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9448 .- 1557-9654. ; 34:5, part 1, s. 1058-1061
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Johannesson, Rolf, et al.
(författare)
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On the distribution of the number of computations in any finite number of subtrees for the stack algorithm
- 1985
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 31:1, s. 100-102
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Tidskriftsartikel (refereegranskat)abstract
- Multitype branching processes have been employed to determine the stack algorithm computational distribution for one subtree. These results are extended here to the distribution of the number of computations in any finite number of subtrees. Starting from the computational distribution forK-1subsequent subtrees, a recurrent equation for the distribution forKsubsequent subtrees is determined.
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