A general analysis of signal strength handover algorithms with cochannel interference

In this paper, the problem of computing cochannel interference statistics i n signal strength measurements in mobile radio systems is presented. In a c ellular environment with cross-correlated log-normal shadowings, extensions of Wilkinson's method and Schwartz and Yeh's method are proposed for evalu ating the statistics of differences between signal strengths that a mobile terminal measures on the links to any pair of base stations in the presence of cochannel interferers. The derived statistics are then used in the perf ormance analysis of relative signal strength handover algorithms. Results p rovided by the two methods are compared with simulation results, in order t o assess their accuracy, and computational issues are addressed. From numer ical results, it is also seen that handover algorithm performance has a not iceable dependence on both cross correlation among shadow fadings and the i nterference level. Finally, it is seen that previous approaches to derive c ochannel interference statistics in the presence of log-normal shadowing ca n be obtained as particular cases.