[Paper Review] Integrated Sensing and Communications: Recent Advances and Ten Open Challenges

Shihang Lu, Fan Liu+12 more|arXiv (Cornell University)|Apr 29, 2023

Sparse and Compressive Sensing Techniques8 citations

TL;DR

This paper provides a comprehensive review of Integrated Sensing and Communications (ISAC), covering theoretical foundations, physical-layer design, networking, and applications, and outlines ten open challenges for future research.

ABSTRACT

It is anticipated that integrated sensing and communications (ISAC) would be one of the key enablers of next-generation wireless networks (such as beyond 5G (B5G) and 6G) for supporting a variety of emerging applications. In this paper, we provide a comprehensive review of the recent advances in ISAC systems, with a particular focus on their foundations, system design, networking aspects and ISAC applications. Furthermore, we discuss the corresponding open questions of the above that emerged in each issue. Hence, we commence with the information theory of sensing and communications (S$\&$C), followed by the information-theoretic limits of ISAC systems by shedding light on the fundamental performance metrics. Next, we discuss their clock synchronization and phase offset problems, the associated Pareto-optimal signaling strategies, as well as the associated super-resolution ISAC system design. Moreover, we envision that ISAC ushers in a paradigm shift for the future cellular networks relying on network sensing, transforming the classic cellular architecture, cross-layer resource management methods, and transmission protocols. In ISAC applications, we further highlight the security and privacy issues of wireless sensing. Finally, we close by studying the recent advances in a representative ISAC use case, namely the multi-object multi-task (MOMT) recognition problem using wireless signals.

Motivation & Objective

• Survey the information-theoretic limits and performance metrics for ISAC systems (S&C).
• Analyze clock synchronization, phase offset issues, and Pareto-optimal signaling strategies for ISAC.
• Discuss ISAC network architectures, resource management, and cross-layer design tailored to sensing and communication needs.
• Examine security, privacy, and MOMT (multi-object multi-task) recognition in wireless sensing.
• Highlight representative ISAC applications and outline future research directions and open questions.

Proposed method

• Review information-theoretic measures for ISAC, including mutual information (MI), Kullback–Leibler Divergence (KLD), and Cramér–Rao bounds (CRB).
• Propose a Pareto-bound framework to characterize the S&C tradeoffs and integration/coordination gains.
• Discuss channel estimation from sensory data and signaling design for sensing-assisted and communication-assisted ISAC.
• Present a classification of ISAC scenarios (monostatic vs bistatic/distributed) and map open questions to these scenarios.
• Summarize recent advances and catalog ten open challenges with potential directions and solutions.

Figure 1: The topology of monostatic/bistatic deployments and single-cell/cooperative scenarios.

Experimental results

Research questions

• RQ1 What are the information-theoretic limits of ISAC systems and how can they be characterized on a Pareto frontier?
• RQ2 How much channel information can be inferred from sensory data in ISAC systems?
• RQ3 How can integration and coordination gains in ISAC be quantified and optimized?
• RQ4 What are the challenges in clock synchronization and phase offset in ISAC deployments?
• RQ5 What is the potential cellular architecture and cross-layer protocol design for future sensing-enabled networks?
• RQ6 How can security, privacy, and MOMT recognition be achieved in ISAC applications?

Key findings

• The paper identifies a set of information-theoretic metrics (MI, KLD, CRB) to evaluate ISAC and discusses their relationships.
• It outlines a weighted MI framework to trace the S&C tradeoff and the existence of a Pareto-optimal boundary.
• It highlights the importance of clock synchronization and phase offset precision for high-resolution sensing and proposes directions to address it.
• It argues for a reimagined cellular architecture where inter-cell signals can be exploited for sensing rather than treated as interference.
• The paper discusses security/privacy concerns and MOMT recognition as critical ISAC-enabled applications, framing them as open research directions.

Figure 2: Structure of this paper and the relevant ISAC scenarios.