Power Allocation for Uplink Sensing and Communication in Cell-free ISAC Systems with Multi-Antenna Users and Multibeam

<p>Driven by the expansion of enhanced mobile broadband and massive machine type communication use cases – including high-accuracy sensing services and radar sensing for autonomous vehicles – integrated sensing and communication using orthogonal frequency division multiplexing has been proposed for sixth generation systems. In this context, studying the possible system arrangements for cell-free networks is important to meet the upcoming requirements imposed on integrated sensing and communication systems. In this work, we evaluate the uplink communication of cell-free systems supporting integrated sensing and communications, i.e., when users transmit simultaneously sensing and communication signals while the access points act as receivers for both. To this end, multi-antenna users employ a multibeam solution for transmitting independent sensing and communication symbols, while adopting either singular value decomposition or angular beamforming. By means of Monte Carlo simulations, we show that the performance of the proposed multibeam solution yields high performance in terms of signal-to-interference-plus-noise ratio for both communication and sensing as well as a low spatial frequency error obtained via angular estimation using the multiple signal classification algorithm.</p>