Handover Protocol Based on Estimated Received Signal Strength for Target Beam in Beam Division Cellular Communication Systems

In this paper, we propose a cellular communication system in which base station (BS) uses smart antenna technology. In the system, BS can form multiple beams toward multiple mobile stations (MS) at the same time to serve those MS simultaneously. To support mobility, handover is the most important function. However, in this system, received pilot signal strength of neighbor BS changes according to the direction of the beam. Therefore, we cannot determine handover to the neighbor BS based on only the received pilot signal strength of the neighbor BS. To solve this problem, we propose an optimal handover scheme in which MS handovers directly from the serving beam of the serving BS to target beam of the target BS. However, this handover scheme requires much scanning time. It leads to much longer handover delay which may cause handover failure. Thus, we propose a new suboptimal handover scheme in which handover decision is made based on estimated received signal strength of target beams. Through analysis and simulation results, we show that the proposed suboptimal handover scheme could improve the outage probability performance of the system and require smaller scanning time.