  Massive multiple-input multiple-output (MIMO) systems are considered as one
of the leading technologies employed in the next generations of wireless
communication networks (5G), which promise to provide higher spectral
efficiency, lower latency, and more reliability. Due to the massive number of
devices served by the base stations (BS) equipped with large antenna arrays,
massive-MIMO systems need to perform high-dimensional signal processing in a
considerably short amount of time. The computational complexity of such data
processing, while satisfying the energy and latency requirements, is beyond the
capabilities of the conventional widely-used digital electronics-based
computing, i.e., Field-Programmable Gate Arrays (FPGAs) and
Application-Specific Integrated Circuits (ASICs). In this paper, the speed and
lossless propagation of light is exploited to introduce a photonic computing
approach that addresses the high computational complexity required by
massive-MIMO systems. The proposed computing approach is based on photonic
implementation of multiply and accumulate (MAC) operation achieved by
broadcast-and-weight (B&W) architecture. The B&W protocol is limited to real
and positive values to perform MAC operations. In this work, preprocessing
steps are developed to enable the proposed photonic computing architecture to
accept any arbitrary values as the input. This is a requirement for wireless
communication systems that typically deal with complex values. Numerical
analysis shows that the performance of the wireless communication system is not
degraded by the proposed photonic computing architecture, while it provides
significant improvements in time and energy efficiency for massive-MIMO systems
as compared to the most powerful Graphics Processing Units (GPUs).
