Achieving unequal error protection via woven codes: Construction and analysis

In this paper several rate R = 2/5 convolutional encoding matrices with four states are used to illustrate how unequal error protection can be achieved for the different positions in the code sequences as well as in the information sequences. Free output- and input-distances and active burst output- and input-distances are computed. Typically a single code cannot combine a large free output- or input-distance with a steep slope. A constructive way to obtain powerful "unequal" coding schemes that provide both large distances and steep slopes is to combine several constituent encoders. Various woven schemes are studied and lower bounds on the active burst output- and input-distances are derived.