Browsing by Author "Huband, Frank L."
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Item A comparison of four coding methods(1968) McCartney, Sheila JoAn; Huband, Frank L.The asymptotic behavior of four coding schemes is evaluated by the norm logQ/log(1/Pe), where Q is an approximation of the amount of computation for decoding, and Pe is the probability of error. The four schemes considered are: (1) Maximum-likelihood decoding, (2) Convolutional codes with syndrome decoding, (3) BCH codes, (4) Finite state and convolutional codes with sequential decoding. Documentation and a listing are included for a computer program which maximizes the frequently used function Eo(8,r) with respect to r for general discrete memoryless channels.Item An improved hybrid coding system for very noisy channels(1970) Agarwal, Ramesh Chandra; Huband, Frank L.Sequential-Algebraic hybrid coding schemes seem to provide efficient error reduction for very noisy channels. One such scheme was proposed by Huband and Jelinek. This hybrid scheme requires large amount, of shift- register storage at the transmitting end. Also, this hybrid scheme does not utilize the available sequential decoding time efficiently. In this thesis, modifications, are proposed to the encoding and decoding schemes of the scheme of Huband and Jelinek. The proposed modification to the encoder eliminates the long shift register requirement, at the cost of additional convolutional encoders. The proposed modification to the decoder utilizes the available sequential decoder time more efficiently, and thus significantly reduces the block erasure probability for the hybrid scheme. The proposed scheme optimally allocates the available sequential decoder cycles to sequential -tracks within a block, so as to minimize the block erasure probability. Upper and lower bounds on the erasure probability for a given allocation are obtained and shown to agree closely with one another. It is shown that the later tracks have available almost all the "equivalent decoder cycles" of the previous unerased tracks.Item The evaluation of a hybrid coding scheme(1970) Fox, Forrest; Huband, Frank L.The performance of a hybrid sequential-algebraic coding scheme is evaluated taking into account the probability of error, the complexity of implementation, and the overall rate. The hybrid scheme is one suggested by Huband and Jelinek based on a similar proposal by Falconer. Upper and lower bounds on the performance of a straight sequential coding scheme have been utilized. The corresponding relationships for the algebraic portion of the hybrid code and the complete hybrid code are obtained. The performance of the hybrid scheme is compared to the performance of a straight sequential scheme, and found to obtain up to several orders of magnitude improvement in probability of error for the, same overall rate and complexity of implementation.