Performance Scaling Laws for PD Array-based Receivers in IM/DD Optical Wireless Communication Systems

TL;DR

This paper analyzes how photodetector array-based receivers in IM/DD optical wireless systems perform as their size increases, revealing the conditions under which they outperform single detectors and emphasizing the importance of joint optimization.

Contribution

It introduces performance scaling laws for PD array receivers, highlighting the need for joint optimization of system parameters to achieve performance gains.

Findings

PD arrays improve performance for narrow beams and high SNR

Increasing PD count alone does not improve performance

Joint optimization of beam pattern, mode, power, and PD placement is essential

Abstract

We study the performance scaling laws for electrical-domain combining in photodetector (PD) array-based receivers employing intensity modulation and direct detection, taking into account the inherent square-law relationship between the optical and electrical received powers. The performance of PD array-based systems is compared, in terms of signal-to-noise ratio (SNR) and achievable rate, to that of a reference receiver employing a single PD. Analytical and numerical results show that PD arrays provide performance gains for sufficiently narrow beams and above an SNR threshold. Furthermore, increasing the number of PDs alone does not enhance performance, and joint optimization of beam pattern, transverse electromagnetic mode, received power, and PD positions is necessary. Our model and derived insights provide practical guidelines and highlight the trade-offs for the design of next-generation high-bandwidth PD array receivers.