Evaluation of 802.11ah TIM and RAW Scheduling Protocol for IoT

A number of MAC scheduling protocols have been proposed in literature and by standardisation groups in order to meet the requirements and specifications of the M2M communication and the Internet of Things (IoT) network. With the fast growth of heterogeneous M2M devices in the IoT network, the MAC protocol design becomes very challenging. New specifications and requirements for IoT and M2M communication are continuously established. This prompted the IEEE WLAN standardisation body to develop the new IEEE 802.11ah standard targeted at accommodating M2M communication into the Internet framework. The standard outlines a number of key enhancements to the Physical (PHY) layer and the Medium Access Control (MAC) layer. The enhancements have been documented and published. The published standard, however, presents ambiguities creating open discussions about the MAC layer. Some of the proposed amendments are not explicit. The standard also provides a large variety of optional enhancements in the MAC layer. This could potentially lead to a number of interoperable issues which can affect the deployment of the standard. This paper focuses on studying the 802.11ah enhancements for scheduling of Stations (STAs) by modelling and evaluating the theoretical limitations of the Traffic Indication Map (TIM) and Restricted Access Window(RAW) features. The paper highlights the potential challenges that may affect the implementation of the protocol from the results of the evaluation presented.