Holographic Integrated Sensing and Communication With Limited Radiation Amplitudes: How Many Quantization Bits Are Enough?
For system designers of holographic ISAC with RHS, this work provides practical guidelines on the required quantization bits, addressing a hardware implementation bottleneck.
This paper investigates the impact of limited radiation amplitude quantization in reconfigurable holographic surfaces (RHS) for integrated sensing and communication (ISAC). It derives closed-form lower bounds for communication rate and sensing SINR, establishing a tight upper bound on the minimum quantization bits needed, and shows that 3-4 bits are sufficient to achieve near-optimal performance.
As a promising solution for extremely large-scale arrays, reconfigurable holographic surfaces (RHS) can be integrated with integrated sensing and communication (ISAC) to form the holographic ISAC paradigm, where significant beamforming gains provided by RHS can improve both communication and sensing performance. However, most existing works on holographic ISAC assume that RHS elements can control the amplitudes of radiated ISAC signals in a continuous manner, which is hard to implement in practice. In this paper, we investigate how the limited radiation amplitudes of the RHS influence ISAC system performance. Specifically, we first derive closed-form lower bounds for both communication rate and sensing SINR to establish a tight upper bound on the minimum radiation amplitude quantization bits. Based on this, we further explore how the communication-sensing performance tradeoff impacts the quantization bits. Numerical results validate our theoretical analysis.