Trellis codes for periodic erasures

This paper describes techniques for the design and analysis of trellis code s that provide reliable communication over every channel in a specified set of possible channels, where each channel is characterized by additive whit e Gaussian noise with a distinct periodic variation in signal-to-noise rati o. An important practical application for such trellis codes is the periodi c erasure channel produced by partial-band interference dispersed by a bloc k interleaver. We present trellis codes that provide reliable communication over all periodic erasure patterns of a given period for which the number of unerased coded bits per period is at least equal to the number of inform ation bits per period.