A QoS-aware scheduling with node grouping for IEEE 802.11ah

The recent IEEE 802.11ah amendment has proven to be suitable for supporting large-scale devices in Internet of Things (IoT). It is essential to provide a minimum level of Quality of Service (QoS) for critical applications such as industrial automation and healthcare. In this paper, we propose a QoS-aware Medium Access Control (MAC) layer solution to enhance network reliability and reduce critical traffic latency by an adaptive station grouping and a priority traffic scheduling scheme. First, a link layer representation of traffic categories as per the delay and reliability requirements is proposed. Second, a novel backoff size-based slot scheduling scheme for Restricted Access Window (RAW) is proposed to support QoS. Third, a grouping scheme is proposed to calculate the current traffic load and balance it among different RAW groups. Finally, a Markov-chain model is developed to study the throughput and latency behaviors of the traffic generated from the critical application. The proposed protocol shows significant delay improvement for priority traffic. The overall throughput performance improves up to 12.7% over the existing RAW grouping scheme.