On Spatial Correlation Properties in Rice Wireless Channels for Physical Layer Security

Spatial (de-)correlation plays an important role in physical layer security for wireless applications, where the presence of an eavesdropper represents a serious concern as long as he/she is closer to the legitimate users than some spatial correlation distance. Reliable evaluation of such distance has therefore paramount importance. This paper presents a general, analytical spatial correlation model tailored to Rice fading channels, whereas most of the existing studies are basically limited to the Rayleigh fading case. Results show that the spatial correlation distance is clearly affected by both the power angle profile at the receiver side and the channel Rice factor. Depending on the propagation conditions, the correlation distance can be significantly larger than the value commonly and hurriedly assumed in many previous works on physical layer security, even several times the commonly assumed half-wavelength correlation distance.