Real-time detection of rectilinear sources for wireless communication signals

This paper proposes a real-time detector of rectilinearity of signals received by an antenna array. A rectilinear source is characterised by having a circularity coefficient of unity and it represents a real-valued source with an arbitrary phase shift. Real-time detection of rectilinearity has been introduced as a new challenge in communications since identifying the rectilinearity of the sources would help designers choose between strictly linear and widely linear beamformers. The proposed real-time detector of rectilinearity, first separates the sources with an online blind source separation (BSS) algorithm, then estimates the circularity coefficient of the separated sources using a real-time circularity tracker. We exploit the result that the variance of the circularity tracker is null for rectilinear signals to tune the algorithm for rapid convergence and robust detection. Simulations on synthetic communication data support the analysis and claims.