On the Error Rate of a Communication System Suffering from Additive Radar Interference

Abstract

In the near future, radar and communication systems will share the spectrum. This motivates the study of how the two systems, which have traditionally operated in different bands, may co-exist. This paper investigates the effect of radar interference (unaltered, beyond the communication system designer's control) on an uncoded communication system, using complex-valued modulation schemes when the Maximum-A-Posteriori (MAP) detector is used. For all commonly used higher order modulation schemes, the Symbol Error Rate (SER) exhibits an "error floor" for the radar interference much larger than the signal power, which can be exactly characterized; in this regime the optimal MAP detector behaves like an interference canceller; interestingly, in this regime the channel behaves as a real-valued phase- fading AWGN channel with receiver CSI, thus indicating a loss of one of the two complex dimensions compared to the complex-valued interference-free channel.