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

Abstract

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 com pared 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.

Channel estimation for LTE downlink in High Altitude Platforms (HAPs) systems

“…The results of measurement are K-factor for elevation angles from 10 o until 90 o by step of 10 0 in frequency carrier 1.2 GHz and 2.4 GHz. Also we evaluates in [4] the performance of fixed power control for Code Division Multiplexing Access (CDMA) and Wideband CDMA (WCDMA) in HAPs environment by using Jakes model with Rician K-factor from our measurement in [3].…”

“…Then, we focus on fast fading that is caused by user velocity to every elevation angles of HAPs. Thus, we use flat fading generated by Jakes model as well as we use in [4].…”

“…By communication established between platform with user terminal on the ground, HAPs have capability to serve more user with lower infrastructure compare to terrestrial networks. Therefore, HAPs has been potential to provide broadband high speed wireless service as complement to terrestrial and satellite systems [3], [4]. HAPs can be aircraft and also airship with altitude in stratosphere at 17-22 km [5]- [7] or 21-25 km [8] above the ground.…”