Performance analysis and enhancement of ieee 802 11 ah wireless lan with restricted access window mechanism

Abstract

IEEE 802.11ah specifies physical (PHY) and medium access control (MAC) layer newlineprotocols for the implementation of sub-1 GHz wireless LAN (WLAN), targeting newlinelarge-scale and low-power Internet of Things (IoT) network scenarios. To provide newlineconnectivity and efficient channel access among a large number of power-constrained newlinestations deployed over a wide area, IEEE 802.11ah standard proposes a novel station newlinegrouping-based medium access mechanism, referred to as restricted access window newline(RAW). In particular, the RAW divides stations into groups, and a group of stations newlineare only allowed to access the channel during a specific time slot (i.e., RAW slot), in newlineorder to reduce contention and collisions in highly dense deployments. When the newlineRAW mechanism is employed, the STAs within a group contend for accessing the newlinechannel using either the distributed coordination function (DCF) or the enhanced newlinedistributed channel access (EDCA) scheme. newlineThe major objective of this research work is to develop analytical models for newlineevaluating the MAC layer performance of IEEE 802.11ah WLANs with RAW mech- newlineanism. The thesis also aims to propose MAC layer enhancements for improving the newlineperformance of IEEE 802.11ah WLANs. In the first part of the thesis, an analyti- newlinecal model has been developed to determine the throughput and the average delay newlineexperienced by successfully transmitted frames in IEEE 802.11ah WLAN with the newlineRAW mechanism, considering saturation as well as non-saturation conditions. The newlinecombined RAW-DCF channel access mechanism has been implemented using the newlinenetwork simulator. Extensive performance evaluation results show that the combined newlineRAW-DCF mechanism can lead to larger throughput and lower average delay in the newlinenetwork, compared to the legacy DCF protocol.In the second part of the thesis, an analytical model has been developed to newlinedetermine the saturation throughput of IEEE 802.11ah WLAN with RAW mechanism, newlinewhere distinct priority classes of traffic are present. newline