Abstract
This paper examines erasure resilience of oversampled filter bank (OFB) codes, focusing on two families of codes based on cosine-modulated filter banks (CMFB). We first revisit OFBs in light of filter bank and frame theory. The analogy with channel codes is then shown. In particular, for paraunitary filter banks, we show that the signal reconstruction methods derived from the filter bank theory and from coding theory are equivalent, even in the presence of quantization noise. We further discuss frame properties of the considered OFB structures. Perfect reconstruction (PR) for the CMFB-based OFBs with erasures is proven for the case of erasure patterns for which PR depends only on the general structure of the code and not on the prototype filters. For some of these erasure patterns, the expression of the mean-square reconstruction error is also independent of the filter coefficients. It can be expressed in terms of the number of erasures, and of parameters such as the number of channels and the oversampling ratio. The various structures are compared by simulation for the example of an image transmission system.
Highlights
The advent of multimedia communication over packetswitched (IP) networks is creating challenging problems in the area of coding
We have discussed the analogies between oversampled filter bank (OFB) and channel codes and showed that signal reconstruction methods derived from the filter banks (FB) theory and coding theory are equivalent even in presence of quantization error
We have further presented a semianalytical analysis of the two OFB structures based on cosinemodulated filter banks (CMFB)
Summary
The advent of multimedia communication over packetswitched (IP) networks is creating challenging problems in the area of coding. Among various JSCC techniques, JSCC based on oversampled transform codes (OTCs) has recently gained a lot of attention [2, 4, 5, 6, 7] This is a fundamentally different approach whereby the error control coding and the signal decomposition are integrated in a single block by using an oversampled filter bank (OFB). The performance analysis as well as the derivation of the reconstruction filters, which are dependent on the erasure patterns, are in addition rendered difficult in the general case of OFB due to the increased order of the generator-polyphase matrix. To proceed with the performance analysis for various types of erasure patterns and with the design of a practical system, we consider OFB codes with generator-polyphase matrices constructed from polyphase matrices of critically sampled cosine modulated filter banks (CMFB) [14, 23].
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