6G and the Post‐Shannon Theory

Since the breakthrough of Shannon's seminal paper, researchers and engineers have worked on codes and techniques that approach the fundamental limits of message transmission. Given the capacity C of a channel and the block length n of the codewords, the maximum number of possible messages that can be transmitted is 2 nC . In this work, we advocate a paradigm change towards Post-Shannon communication that allows the encoding of up to 2 2 nC messages: a double exponential behavior! This paradigm shift is the study of the transmission of the Gestalt information instead of message-only transmission and involves a shift from the question of what message the sender has transmitted to whether it has transmitted at all, and with the purpose of achieving which goal. Entire careers were built designing methods and codes on top of previous works, bringing only marginal gains in approaching the fundamental limit of Shannon's message transmission. This paradigm change can bring not only marginal but also exponential gains in the efficiency of communication. Within Post-Shannon techniques, we will explore identification codes, the exploitation of resources that are considered useless in the current paradigm such as noiseless feedback common randomness, and the exploitation of multi-channel descriptor information.