This chapter presents a comprehensive study aimed at developing a general theory for communication systems that extends beyond the traditional Shannon framework, focusing on the emerging requirements of 6G technology. With increasing interest in secure identification schemes for communication over noisy channels, we survey existing results in this domain. Additionally, we explore scenarios involving adversaries who not only eavesdrop but also actively interfere with communication, such as through jamming or other disruptive actions.
Our investigation highlights experimental advancements in message identification, a post-Shannon communication paradigm that shows promise for addressing critical challenges in 6G networks. Key findings demonstrate that resources such as feedback and common randomness significantly enhance message identification by reducing latency, increasing capacity, and improving overall performance. Identification codes, developed to support practical applications, are now being implemented, and the generation of common randomness emerges as an essential tool for post-Shannon communication.
We also provide an overview of real-time monitoring systems, which typically involve a sensor observing a plant and relaying state measurements to a remote monitor via a wireless link. In control systems the monitor is replaced by a controller, which acts on the plant to achieve a desired state, forming a closed control loop. A notable example is a Wireless Networked Control System (WNCS), where concepts like the “age of information” play a critical role.
Reliable communication over noisy channels remains foundational, supported by channel coding techniques. For example, the Guessing Random Additive Noise Decoding (GRAND) algorithm provides a universal decoding method for arbitrary linear codes. Instead of directly identifying the transmitted codeword, GRAND deduces the most likely noise sequence and validates the resulting codeword against the codebook, enabling its applicability to any coding scheme.
Another emerging area of focus is Functional Compression (FC), a novel paradigm that transmits only the information necessary to achieve a specific goal, thereby reducing communication overhead. Rooted in goal-oriented communication, FC prioritizes the efficient fulfillment of particular tasks, representing another significant step beyond Shannon's traditional framework. This work not only surveys the state-of-the-art but also underscores the transformative potential of these post-Shannon paradigms in shaping the future of 6G communication systems.