Hidden terminal-aware access point selection for IEEE 802.11ah networks

Connectivity provisioning in large-scale Internet-of-Things (IoT) networks raises several challenges, one of which is the high collision rate among the transmission attempts of IoT devices. Transmission collisions result in prolonged data delivery delay and increased energy consumption of IoT devices. Contention-based wireless communication technologies such as WiFi is particularly vulnerable to this issue. As a remedy, a new standard IEEE 802.11ah is designed and such methods as RAW (Restricted Access Window) grouping is incorporated in order to curb the high collision rate. Meanwhile, in IEEE 802.11ah the transmission range and the number of devices that can be accommodated are also drastically increased. As a result, the impact of the hidden terminal problem is significantly amplified, which causes transmission collisions. In this paper, we propose an approach to avoid the high collision rate at the phase of the AP(Access Point) selection for IEEE 802.11ah networks. The proposed scheme considers the traffic load balancing and the hidden terminal issue simultaneously, without incurring any burden to the IoT devices. No modification of the IEEE 802.11ah standard is needed. Via extensive NS-3 simulations, we have verified that the proposed AP selection scheme outperforms the existing schemes in terms of data delivery delay and energy consumption by reducing transmission collisions.