Downlink capacity of high altitude Platforms CDMA system in ricean channel

High altitude Platforms (HAPs) are known as a new means to provide high quality broadband applications and CDMA based IMT-2000 (3G) wireless service. For the capacity estimation of HAPs system, most previous work was restricted to the additive white Gaussian noise (AWGN) channels neglecting the effect of multipath fading. In this paper, we investigate the downlink capacity of HAPs CDMA system in ricean fading channel. The downlink multiple access interference for HAPs CDMA system in ricean channel is derived with Gaussian approximation method. Then the downlink capacity which is related to the antenna array gain patterns, the required Eb/I0 and the CDMA processing gain is obtained. The results show that the downlink capacity decreases dramatically when the elevation decreases.