Abstract
This paper proposes a novel听 technique 听to prove a听 one - shot 听version of听 achievability 听 results 听in听 network information 听 theory . The听 technique 听is not based on covering and packing lemmas. In this听 technique , we use a stochastic encoder and decoder with a particular structure for coding that resembles both the ML and the joint-typicality coders. Although stochastic encoders and decoders do not usually enhance the capacity region, their use simplifies the analysis. The Jensen inequality lies at the heart of error analysis, which enables us to deal with the expectation of many terms coming from stochastic encoders and decoders at once. The听 technique 听is illustrated via four examples: point-to-point channel coding, Gelfand-Pinsker, broadcast channel and Berger-Tung problem of distributed lossy compression. Applying the听 one - shot 听 result 听for the memoryless broadcast channel in the asymptotic case, we get the entire region of Marton's inner bound without any need for time-sharing. Also, these听 results 听are employed in conjunction with multi-dimensional berry-esseen CLT to听 derive new regions for finite-blocklength regime of Gelfand-Pinsker.