Sequential decoding

About: Sequential decoding is a research topic. Over the lifetime, 8667 publications have been published within this topic receiving 204271 citations.

A class of binary recurrent codes with limited error propagation

Abstract: A class of binary recurrent codes for correcting independent errors is given which has guaranteed error-limiting properties. These codes can be simply decoded using threshold decoding, and will recover from any decoding error caused by either an uncorrectable transmission error or a temporary malfunction of the encoder or decoder. A number of such codes are given along with a synthesis procedure. The results of a computer simulation are given which indicate that these codes perform better in some situations than other codes using threshold decoding.

A lower bound to the distribution of computation for sequential decoding

Abstract: In sequential decoding, the number of computations which the decoder must perform to decode the received digits is a random variable. In this paper, we derive a Paretian lower bound to the distribution of this random variable. We show that P [C > L] L^{-\rho} , where C is the number of computations which the sequential decoder must perform to decode a block of \Lambda transmitted bits, and is a parameter which depends on the channel and the rate of the code. Our bound is valid for all sequential decoding schemes and all discrete memoryless channels. In Section II we give an example of a special channel for which a Paretian bound can be easily derived. In Sections III and IV we treat the general channel. In Section V we relate this bound to the memory buffer requirements of real-time sequential decoders. In Section VI, we show that this bound implies that certain moments of the distribution of the computation per digit are infinite, and we determine lower bounds to the rates above which these moments diverge. In most cases, our bounds coincide with previously known upper bounds to rates above which the moments converge. We conclude that the performance of systems using sequential decoding is limited by the computational and buffer capabilities of the decoder, not by the probability of making a decoding error. We further note that our bound applies only to sequential decoding, and that, in certain special cases (Section II), algebraic decoding methods prove superior.

Memory Management in a Viterbi Decoder

Abstract: Management of the memory contents in a Viterbi decoder is a major design problem for both hardware and software realizations. In a naive implementation, every bit in the memory must be changed (read, modified, and rewritten) for each message bit decoded, and, in addition, some double buffering is required. An especially annoying feature is the need to read and rewrite long words, forty bits in a typical case. In this note we describe a memory organization which overcomes these problems. The techniques described here are not novel, but neither are they widely known.

A squaring method to simplify the decoding of orthogonal space-time block codes

Abstract: We present a squaring method to simplify the decoding of orthogonal space-time block codes in a wireless communication system with an arbitrary number of transmit and receive antennas. Using this squaring method, a closed-form expression of signal-to-noise ratio after space-time decoding is also derived. It gives the same decoding performance as the maximum-likelihood ratio decoding while it shows much lower complexity.