The two enantiomers of 2',3'-dideoxy-3'-thiacytidine (BCH-189) and their 5-fluoro analogs (FTC) were found to be good substrates for human 2'-deoxycytidine kinase with Km values in the 5.7 to 42.1 microM range. The affinity of the (-)-enantiomers was greater than that of the (+)-compounds. These results may explain the greater in vitro antiviral potency against human immunodeficiency virus and ...

Absrrucr -The BCH algorithm can be extended to correct more errors than indicated by the BCH bound. In the first step of the decoding procedure, we correct a number of errors, corresponding to a particular case of the Hartmann-Tzeng bound. In the second step we aim at full error correction. A measure for the worst-case number of field elements of an extension field GF(2") that must be tested fo...

It is shown that a classical error correcting code C = [n, k, d] which contains its dual, C⊥ ⊆ C, and which can be enlarged to C ′ = [n, k′ > k + 1, d′], can be converted into a quantum code of parameters [[n, k + k′ − n,min(d, d3d′/2e)]]. This is a generalisation of a previous construction, it enables many new codes of good efficiency to be discovered. Examples based on classical Bose Chaudhur...

Bit Error Rate (BER) performance of the modified structure of a Digital Phase Locked Loop (DPLL) based system for dealing with Nakagami-m fading with coded and un-coded channel is presented here. The emphasis of the work is the implementation of Bose, Chaudhuri and Hocquenghem (BCH) channel coding and decoding technique. The performance of the DPLL for carrier reception with signal under certai...

A low-complexity step-by-step decoding algorithm for t-error-correcting binary Bose-Chaudhuri-Hocquenghem (BCH) codes is proposed. Using logical analysis, we obtained a simple rule which can directly determine whether a bit in the received word is correct. The computational complexity of this decoder is less than the conventional step-by-step decoding algorithm, since it reduces at least half o...

We recall a classic lower bound on the minimum Hamming distance of constacyclic codes over finite fields, analogous to well-known BCH for cyclic codes. This BCH-like serves as foundation proposing some minimum-distance bounds single-generator quasi-twisted (QT) Associating each QT code with an extension field, we obtain first bound. is analogue result in literature quasi-cyclic point out weakne...

It is shown in this paper that the iterative algorithm introduced by Berlekamp for decoding BCH codes actually provides a general solution to the problem of synthesizing the shortest linear feedback shift register capable of generating a prescribed finite sequence of digits. The shit-register approach leads to a simple proof of the validity of the algorithm as well as providing additional insig...

We present a parallel version of Viterbi’s decoding procedure, for which we are able to demonstrate that the resultant task graph has restricted complexity in that the number of communications to or from any processor cannot exceed 4 for BCH codes. The resulting algorithm works in lock step making it suitable for implementation on a systolic processor array, which we have implemented on a field...

In this paper, Block Turbo Codes (BTC), that is product codes obtained from the concatenation of either two extended or two expurgated BCH codes are evaluated for the HIPERLAN/2 system. Simulations show that only expurgated BTC outperforms the performance of the Convolutional Code (CC) specified in the standard. This result is surprising since expurgated and extended BTC have same performance o...

The trellis complexity of the Preparata and Goethals codes is examined. It is shown that at least for a given set of permutations these codes are rectangular. Upper bounds on the state complexity profiles of the Preparata and Goethals codes are given. The upper bounds on the state complexity of the Preparata and Goethals codes are determined by the DLP of the extended primitive doubleand triple...