Joint source-channel LZ´77 coding

Limited memory and bounded communication resources require powerful data compression techniques, but at the same time noisy tetherless channels and/or corrupted file systems need error correction capabilities. Joint source-channel coding has emerged as a viable solution to this problem. The first practical joint source-channel coding algorithm was presented capable of correcting errors in the popular Lempel-Ziv´77 scheme without practically losing any compression power. This is possible since the LZ´77 (as well as gzip) encoder does not completely remove all redundancy. The inherent additional redundancy left by LZ´77 encoder was used succinctly by a channel coder (e.g., Reed Solomon coder) to protect against a limited number of errors. In addition to these, the scheme proposed is perfectly backward-compatible that is, a file compressed with error-resilient LZ´77 can still be decompressed by a common LZ´77 decoder. Algorithms and supporting experimental data were presented to support the system´s claims and theoretical justifications.