Communication systems to date primarily aim at reliably communicating bit sequences. Such an approach provides efficient engineering designs that are agnostic to the meanings of the messages or to the goal that the message exchange aims to achieve. Next generation systems, however, can be potentially enriched by folding message semantics and goals of communication into their design. Further, these systems can be made cognizant of the context in which communication exchange takes place, thereby providing avenues for novel design insights. This tutorial summarizes the efforts to date, starting from its early adaptations, semantic-aware and task-oriented communications, covering the foundations, algorithms and potential implementations. The focus is on approaches that utilize information theory to provide the foundations, as well as the significant role of learning in semantics and task-aware communications.

To accommodate new applications such as extended reality, fully autonomous vehicular networks and the metaverse, next generation wireless networks are going to be subject to much more stringent performance requirements than the fifth-generation (5G) in terms of data rates, reliability, latency, and connectivity. It is thus necessary to develop next generation advanced transceiver (NGAT) technologies for efficient signal transmission and reception. In this tutorial, we explore the evolution of NGAT from three different perspectives. Specifically, we first provide an overview of new-field NGAT technology, which shifts from conventional far-field channel models to new near-field channel models. Then, three new-form NGAT technologies and their design challenges are presented, including reconfigurable intelligent surfaces, flexible antennas, and holographic multi-input multi-output (MIMO) systems. Subsequently, we discuss recent advances in semantic-aware NGAT technologies, which can utilize new metrics for advanced transceiver designs. Finally, we point out other promising transceiver technologies for future research.

This tutorial reviews fundamental contributions to information security. An integrative viewpoint is taken that explains the security metrics, including secrecy, privacy, and others, the methodology of information-theoretic approaches, along with the arising system design principles, as well as techniques that enable the information-theoretic designs to be applied in real communication and computing systems. The tutorial, while summarizing these contributions, argues for the simultaneous pivotal role of fundamental limits and coding techniques for secure communication system design.

Age of information (AoI) is a performance metric that measures the timeliness and freshness of information, and is particularly relevant in applications with time-sensitive data. This paper studies average AoI minimization in cognitive radio energy harvesting communications. More specifically, the system studied has a primary user with access rights to spectrum, and a secondary user who can utilize the spectrum only when it is left idle by the primary user. The secondary user is an energy harvesting sensor that harvests ambient energy with which it performs spectrum sensing and status updates of its sensing data to a destination. The status-updates are sent by opportunistically accessing the primary user’s spectrum. The secondary user aims to minimize the average AoI by adaptively making sensing and update decisions based on its energy availability and the availability of the primary spectrum with either perfect or imperfect spectrum sensing. The sequential decision problems are formulated as partially observable Markov decision processes and solved by dynamic programming for finite and infinite horizon. The properties of the optimal sensing and updating policies are investigated and shown to have threshold structure. Numerical results are presented to confirm the analytical findings.

This paper proposes a communication framework where meanings of transmitted codewords over a noisy channel are explicitly taken into account. Furthermore, such communication takes place in the presence of an external entity, i.e., an agent, that can influence the receiver. The agent may be adversarial or helpful, and its true nature is unknown to the communicating parties. Actions taken by the agent are governed by its nature to aim to improve/deteriorate the communication performance. We characterize the optimal transmission policies to minimize the end-to-end average semantic error, that we define as the expected error between meanings of intended and recovered messages, under the uncertainty of agent’s true intentions. To do so, we first formulate the communication problem as a Bayesian game, and investigate the conditions under which a Bayesian Nash equilibrium exists. Next, we consider a dynamic communication scenario in which parties take actions sequentially, forming beliefs about the other party. By formulating this setting as a sequential game, we investigate the structure of the belief system and strategy profiles at equilibrium. Our results indicate that word semantics are instrumental in assessing communication performance when messages carry meanings, and optimal communication strategies are strongly influenced by the communicating parties’ beliefs.

This work considers the problem of mitigating information leakage between communication and sensing in systems jointly performing both operations. Specifically, a discrete memoryless state-dependent broadcast channel model is studied in which (i) the presence of feedback enables a transmitter to convey information, while simultaneously performing channel state estimation; one of the receivers is treated as an eavesdropper whose state should be estimated but which should remain oblivious to part of the transmitted information. The model abstracts the challenges behind security for joint communication and sensing if one views the channel state as a key attribute, e.g., location. For independent and identically distributed states, perfect output feedback, and when part of the transmitted message should be kept secret, a partial characterization of the secrecy-distortion region is developed. The characterization is exact when the broadcast channel is either physically-degraded or reversely-physically-degraded. The partial characterization is also extended to the situation in which the entire transmitted message should be kept secret. The benefits of a joint approach compared to separation-based secure communication and state-sensing methods are illustrated with binary joint communication and sensing models.