Advances in IEEE 802.11ah standardization for machine-type communications in sub-1GHz WLAN

The IEEE 802.11ah task group has been formed to develop the specification for sub-1GHz WLAN. Due to the low operating frequency, it is expected that the 802.11ah can support coverage up to 1km. Such large coverage is well-suited for machine-to-machine (M2M) or machine-type communication (MTC) applications like smart grid and sensor networks. These applications are characterized by large number of operating devices, small data packet size, and low-power operation, and they pose new problems that conventional 802.11 WLAN is not capable to address. Therefore they stimulate significant interest and discussion in the task group to define enhancements to improve the performance of 802.11ah WLAN. The objective of this paper is to present the recent advances in the IEEE 802.11ah standardization to enhance the MTC performance. In particular the emphasis is on the channel access enhancement, which lies in the core of MAC layer. Relevant works in the research community are also reviewed in the hope that they may be utilized to further optimize the 802.11ah WLAN.