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- Johannesson, Rolf, et al.
(författare)
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Further results on binary convolutional codes with an optimum distance profile
- 1978
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 24:2, s. 264-268
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Tidskriftsartikel (refereegranskat)abstract
- Fixed binary convolutional codes are considered which are simultaneously optimal or near-optimal according to three criteria: namely, distance profiled, free distanced_{ infty}, and minimum number of weightd_{infty}paths. It is shown how the optimum distance profile criterion can be used to limit the search for codes with a large value ofd_{infty}. We present extensive lists of such robustly optimal codes containing rateR = l/2nonsystematic codes, several withd_{infty}superior to that of any previously known code of the same rate and memory; rateR = 2/3systematic codes; and rateR = 2/3nonsystematic codes. As a counterpart to quick-look-in (QLI) codes which are not "transparent," we introduce rateR = 1/2easy-look-in-transparent (ELIT) codes with a feedforward inverse(1 + D,D). In general, ELIT codes haved_{infty}superior to that of QLI codes.
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| 6. |
- Johannesson, Rolf
(författare)
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On the distribution of computation for sequential decoding using the stack algorithm
- 1979
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 25:3, s. 323-331
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Tidskriftsartikel (refereegranskat)abstract
- An analytical procedure is presented for generating the computational distribution for the Zigangirov-Jelinek stack algorithm. Multitype branching processes are employed to develop a procedure for estimating sequential decoding computation, without the need for simulation, but with sufficient accuracy to be a valid design tool. At information rates about the cutoff rateR_{o}the calculated computational performance is virtually Identical to that obtained by time consuming simulations.
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| 7. |
- Johannesson, Rolf
(författare)
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On the error probability of general trellis codes with applications to sequential decoding
- 1977
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 23:5, s. 609-611
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Tidskriftsartikel (refereegranskat)abstract
- An upper bound on the average error probability for maximum-likelihood decoding of the ensemble of randomL-branch binary trellis codes of rateR = 1/nis given which separates the effects of the tail lengthTand the memory lengthMof the code. It is shown that the bound is independent of the lengthLof the information Sequence whenM geq T + [nE_{VU}(R)]^{-1} log_{2} L. The implication that the actual error probability behaves similarly is investigated by computer simulations of sequential decoding utilizing the stack algorithm. These simulations confirm the implication which can thus be taken as a design rule for choosingMso that the error probability is reduced to its minimum value for a givenT.
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| 8. |
- Johannesson, Rolf
(författare)
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Robustly-optimal rate one-half binary convolutional codes
- 1975
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 21:4, s. 464-468
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Tidskriftsartikel (refereegranskat)abstract
- Three optimality criteria for convolutional codes are considered in this correspondence: namely, free distance, minimum distance, and distance profile. Here we report the results of computer searches for rate one-half binary convolutional codes that are "robustly optimal" in the sense of being optimal for one criterion and optimal or near-optimal for the other two criteria. Comparisons with previously known codes are made. The results of a computer simulation are reported to show the importance of the distance profile to computational performance with sequential decoding.
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| 9. |
- Johannesson, Rolf
(författare)
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Some long rate one-half binary convolutional codes with an optimum distance profile
- 1976
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 22:5, s. 629-631
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Tidskriftsartikel (refereegranskat)abstract
- This correspondence gives a tabulation of long systematic, and long quick-look-in (QLI) nonsystematic, rateR = 1/2binary convolutional codes with an optimum distance profile (ODP). These codes appear attractive for use with sequential decoders.
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| 10. |
- Johannesson, Rolf
(författare)
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Some rate 1/3 and 1/4 binary convolutional codes with an optimum distance profile
- 1977
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 23:2, s. 281-283
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Tidskriftsartikel (refereegranskat)abstract
- A tabulation of binary systematic convolutional codes with an optimum distance profile for rates1/3and1/4is given. A number of short rate1/3binary nonsystematic convolutional codes are listed. These latter codes are simultaneously optimal for the following distance measures: distance profile, minimum distance, and free distance; they appear attractive for use with Viterbi decoders. Comparisons with previously known codes are made.
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