Adaptive softer handover algorithm for high altitude platform station UMTS with onboard power resource sharing

In the high altitude platform station (HAPS) Universal Mobile Telecommunications System (UMTS), the power resource onboard the platform can be shared among all base stations since all the base stations´ transmit antenna beams originate from the same phased array antenna onboard the platform. An adaptive softer handover (SHO) algorithm for HAPS UMTS with onboard power resource sharing is proposed. The algorithm uses both the platform´s downlink output power and individual base stations´ downlink output powers to dynamically adjust the mobiles´ SHO add and drop margins. Simulation results obtained show that with proper selection of design parameters, the proposed adaptive SHO algorithm outperforms the conventional SHO algorithm in both quality of service and resource utilization.