Name
Abstract | ||
|---|---|---|
For output-symmetric discrete memoryless channels (DMCs) at even moderately high rates, fixed-block-length communication systems show no improvements in their error exponents with feedback. This paper studies systems with fixed end-to-end delay and shows that feedback generally provides dramatic gains in the error exponents. A new upper bound (the uncertainty-focusing bound) is given on the probability of symbol error in a fixed-delay communication system with feedback. This bound turns out to have a form similar to Viterbi's bound used for the block error probability of convolutional codes as a function of the fixed constraint length. The uncertainty-focusing bound is shown to be asymptotically achievable with noiseless feedback for erasure channels as well as for any output-symmetric DMC that has strictly positive zero-error capacity. Furthermore, it can be achieved in a delay-universal (anytime) fashion even if the feedback itself is delayed by a small amount. Finally, it is shown that for end-to-end delay, it is generally possible at high rates to beat the sphere-packing bound for general DMCs - thereby providing a counterexample to a conjecture of Pinsker. |
Year | DOI | Venue |
|---|---|---|
2008 | 10.1109/TIT.2008.920339 | IEEE Transactions on Information Theory |
Keywords | Field | DocType |
random coding,block length,sphere-packing bounds,fixed end-to-end delay,fixed-block-length communication system,fixed constraint length,index terms feedback,reliability functions,symbol error,block error probability,high rate,queuing,noiseless feedback,list decoding.,hybrid arq,error exponent,end-to-end delay,fixed-delay communication system,anytime reliabil ity,delay,delay behave differently,information theory,end to end delay,communication system,feedback,list decoding,erasure channel,channel coding,error probability,monte carlo methods,automatic repeat request,reliability function,convolutional code,sphere packing,indexing terms,convolutional codes,upper bound,communication systems,block codes | Hybrid automatic repeat request,Discrete mathematics,Convolutional code,Upper and lower bounds,Block code,Counterexample,Decoding methods,List decoding,Mathematics,Viterbi algorithm | Journal |
Volume | Issue | ISSN |
54 | 5 | 0018-9448 |
Citations | PageRank | References |
25 | 2.36 | 27 |
Authors | ||
1 | ||