ISAC in future wireless networks: challenges, opportunities, and performance analysis.

Abstract

With wireless networks continuously evolving, and with the goal of accommodating technologies and applications that are not only functional but also centered around the effective use of resources, ISAC proves to be a practical and promising candidate. For the longest time, wireless networks have been centered around providing high-rate communication, but with Integrated Sensing and Communication (ISAC) we are moving toward a system that not only supports conventional communication, but also sensing capabilities, enabling localization, environment perception, and context-aware operation through shared waveforms, spectrum, and hardware. ISAC is the key enabler for 6G requirements, and while its possible implementation is being actively discussed, and researched upon, several challenges remain. This thesis investigates some of the integration challenges and opportunities of ISAC in the context of future wireless systems. For the analysis, a communication-centric ISAC implementation based on a 5G New Radio (NR) waveform is evaluated through MATLAB simulations. The simulation reuses the Demodulation Reference Signal (DM-RS) pilots, which were originally designed for channel estimation, to perform bistatic sensing and extract range, angle-of-arrival, and Doppler information without requiring a dedicated sensing waveform. The simulation examines the influence of four key physical-layer parameters, which are the antenna array configuration, channel bandwidth, transmit power, and scatterer density, on target tracking accuracy. The results show that the channel bandwidth is the dominant factor governing range resolution and tracking stability, while antenna aperture significantly affects angle-of-arrival resolution. Transmit power was found to have a negligible impact under high signal-to-noise ratio conditions. Also, a systematic sweep of the DM-RS additional position parameter reveals a fundamental sensing–communication tradeoff, where having denser pilot configurations expand the maximum unambiguous Doppler range by a factor of four, at the cost of approximately 10% reduction in data throughput. A controlled bistatic Doppler validation experiment confirms these theoretical limits, demonstrating that having inadequate pilot density results in Doppler aliasing and complete tracking failure. The results demonstrate that effective ISAC system design requires an efficient co-optimisation of bandwidth, antenna configuration, clutter management, and pilot density, and that the DM-RS density parameter serves an important use for balancing sensing capability against communication capacity in 5G NR-based ISAC systems.