Optical wireless (OW) communications, besides being of great interest for indoor and outdoor applications, have been recently proposed as a powerful alternative to the existing wired and wireless radio frequency (RF) interconnects in a network-on-chip (NoC). Design and analysis of networks with OW links require a careful investigation of cross-link interference, which impacts considerably the efficiency of systems that reuse the same channel for multiple transmissions. Yet, there is no comprehensive analysis of interference for OW NoCs, and the analyses of crosstalk in optical waveguide communications usually rely on synchronous data transmissions. A novel framework for the analysis of on-chip OW communications in the presence of cross-link cochannel interference and noise is proposed, where asynchronous data transmissions are considered. Self-beating of interfering signals is also considered, which was often neglected in previous literature. The bit error probability (BEP) for arbitrary number of interfering sources is derived as a function of signal-to-noise ratio (SNR), interference powers, detection threshold and pulse shaping, using both exact and approximation methods. The proposed analysis can be applied to both noise- and interference-limited cases, and enables a system designer to evaluate reuse distance between links that share the same optical carrier for simultaneous communication in NoCs.

Optical wireless (OW) links have been recently proposed as an interconnection technology for multiple processing cores operating in parallel on the same chip. OW communication is also a mature option for indoor and outdoor applications. Design and analysis of networks with optical wireless links require a careful investigation of cross-link interference which plays a key-role on the performance and efficiency of systems that reuse the same channel for multiple parallel transmissions. In this paper we analyze the bit-error rate performance of OW links for on-chip applications with cross-link cochannel interference. As a novelty with respect to known literature on crosstalk in optical communications we consider asynchronous data transmission and address the system performance in case of heavy interference. Analytical methods are used to derive error probabilities as a function of signal-to-noise ratio (SNR), crosstalk power ratio, detection threshold, pulse shaping. Both exact and tight approximation methods are considered. As shown in the results, robustness against interference increases with asynchronous transmission, RZ pulse shaping and suitable design of detection threshold. It is also shown how the proposed analysis can be used to evaluate the reuse distance between two parallel links simultaneously transmitting in the same direction.