Performance Enhancement of LTE Using Receiver Diversity Combining in HAPS Communication Channel

Abstract

This paper studies the performance enhancement of Long Term Evolution (LTE) downlink, which employs a High Altitude Platform Station (HAPS) as a radio communication channel. Transmission of LTE signal into HAPS channel is evaluated based on reception diversity mode in various combining schemes such as selection combining (SC), equal gain combining (EGC) and maximal ratio combining (MRC). The performance evaluations are simulated using bit error rate (BER) metric in different elevation angles from HAPS to ground user, velocities of user and channel estimation conditions. For all the investigated combining schemes, simulation results demonstrate that MRC and EGC exhibited a better performance than SC. Additionally, the performance enhancement for stationary user is better than higher user velocity. Furthermore, the performance gets closer between higher elevation angles in each combining scheme. Finally, it has been found that MRC provides the best performance when HAPS channel is perfectly estimated.