Directional traffic-aware intra-hap handoff Scheme for hap communications systems

In this paper, a novel directional traffic-aware intra-HAP handoff scheme (DTAHS) is proposed. In this, users in overlapping areas of overloaded cells may be forced to hand off earlier than their optimal handoff boundaries, in order to partially balance the traffic among the adjacent cells. The new scheme provides a good compromise between the new-call-blocking probability and the handoff-call-dropping probability, when the overlap interval between adjacent cells is relatively short. Simulation results show that the new scheme outperforms both the load-balancing handoff scheme (LBHS) and the cooperative directional intra-HAP handoff scheme (CDHS) when the factor value associated with call blocking is smaller than 0.8 and bigger than 0.4 for a relatively short overlap interval. It can be also concluded that the variation of new-call-blocking probability for different overlap intervals is lower than that of the handoff-call-dropping probability. The load-balancing handoff scheme and the directional traffic-aware intra-HAP handoff scheme are suitable for the long and short overlap interval cases, respectively.