Coding on Dual-Parameter Barrier Channels

This paper studies coding on channels with the barrier property: only errors to and from a special barrier symbol are possible. This model is motivated by information systems that have heterogeneous symbol structure, not admitting the usual multi-bit scaling principle of representation levels. This work is the first that addresses a barrier channel with separate parameters for the transitions into and out of the barrier symbol. Earlier work addressed special-case single-parameter models, and focused primarily on the worst-case coding performance. Our contributions for the general dual-parameter model include derivation of the channel capacity, guaranteed-correction conditions and code-size bounds, a code construction method, and several decoders that correct beyond the guaranteed worst-case capability. A key structural feature of our construction method enables reduction of the decoding problem to a cooperation between two decoders for codes in the Hamming metric.