Interference rejection combining in two-tier femtocell networks

A femtocell technology-towards the deployment of small-cell networks-is a key enabling feature for future wireless networks to improve indoor coverage and throughput per network area at a low cost. However, these small-cell networking inevitably increases cochannel interference due to aggressive (even uncontrolled) reuse of spectral resources. One of the attractive approaches to alleviating the cochannel interference is a multiple-antenna technique, where accurately characterizing the effects of cross- and co-tier interference on the performance of multiple-antenna communications is crucial but challenging. We apply superanalysis framework to provide further numerical results on the optimum combining diversity systems in an uplink two-tier femtocell network. Specifically, we consider that a single-antenna femtocell user (transmitter) communicates with a closed femtocell access point (receiver) with multiple antennas in the presence of single-antenna cochannel interferers from co-tier (femtocells) and cross-tier (macrocell) networks. We then quantify the cross- and co-tier interference effects in terms of degrees of interference power heterogeneity and spatial correlation.