Communication Under Channel Uncertainty
نویسندگان
چکیده
In this lecture we study the problem of communication under channel uncertainty. The performance of the communication scheme, in addition to being governed by achieving the optimal rate, is characterized by a vanishing probability of decoding error. A universal decoder for a family of channels is a scheme which has no prior knowledge of the particular channel from this class over which transmission takes place, and yet achieves the same random coding error exponent as the optimal decoder. Ziv’s decoding algorithm [2, 3] is presented, which is based on the Lempel-Ziv (LZ) incremental string parsing algorithm [1], and is shown to be universal for the class of all finite state channels. We begin with some notation in section 2 before introducing the concept of universality in section 3 and the LZ based decoding algorithm in section 5, with a sketch of the proof of its optimality in section 6.
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