On the evaluation of fixed step closed loop power control for CDMA High Altitude Platforms (HAPs) communication channel

摘要

This paper describes the performance evaluation of fixed step closed loop power control algorithm in a novel wireless channel that is called High Altitude Platforms (HAPs). This new wireless delivery method is proposed as a complementary system in providing the next generation services in which the technology basically employs CDMA. In HAPs communication, the channel is predicted to have different characteristic compared to that in terrestrial channel. In this work, HAPs channel is modeled to follow Ricean fading distribution whose K factor is obtained based on experimental measurement. Fixed step power control algorithm is then computer simulated under such a channel to evaluate its performance. The performance is presented in terms of step size of the power control, users elevation angle, feedback delay, and SIR estimation error. We found the performance of fixed step closed loop power control in HAPs channel increases with the increase of step size and elevation angle. Feedback delay has insignificant effect to the power control performance. SIR estimation error degrades the performance of the power control compared with the true SIR estimation.