The Impact of Using Multiple HAPSs to Combat Platform Instability on Uplink CDMA Capacity

High altitude platform stations (HAPSs) are widely known as an alternative means to provide broadband applications and code division multiple access (CDMA) based international mobile telecommunications-2000 (IMT-2000) communications. Previous studies have shown that platform instability caused by stratospheric winds may lead to system level performance degradation. In this paper, we propose to combat this problem by using multiple HAPSs to provide diversity of signal reception. Though the proposed scheme would enhance the reliability of service provision, the required uplink transmitting power may need to be increased to ensure that every serving HAPS receives at least the target receive power. This will elevate the interference level and may adversely affect the uplink capacity. Numerical analysis is thus performed to investigate the impact of using multiple HAPSs on the uplink capacity.