Optimal access point switching with per-link threshold under nonhomogeneous bandwidth allocation

This paper investigates optimal switching between coordinated Access Points (APs). Since a user has difficulty in gathering the full instantaneous channel information from all the surrounding APs, per-link information between an AP and the user is assumed available at a time and is compared with a predetermined threshold to determine either switching or staying. Unlike the existing studies on switch-and-stay combining techniques, AP switching in this paper deals with nonhomogeneous bandwidth allocation between potential switching branches. Optimal per-link thresholds are provided by assuming Rayleigh fading channels between AP and the user. The expected capacity achieved by the proposed threshold-based switching obviously depends on the order of comparison. With numerical investigation, the comparison sequence determined from a decreasing order of per-link average capacity is shown the best one. Another sequence obtained using an upper bound of the per-link average capacity is also shown promising, which is greatly easy to compute.