The Claim-based Priority-Discriminated Channel Access (CPDCA) Method using the Registered Backoff Time Mechanism for IEEE 802.11ah

IEEE 802.11ah is a protocol that adopts the CSMA/CA-based channel access way for Internet of Thing (IOT). This work proposed a newly devised Restricted Access Window (RAW) called the Claiming RAW to let those spontaneous stations having high priority’s uplinked data frames do claims of intending to uplink high priority’s data to reduce collisions. In addition, instead of generating the random backoff time after the collision happens, which the regular CSMA/CA-based 802.11* protocols adopt, this work adopted the registered backoff time mechanism, for which a station registers its next backoff time to IEEE 802.11ah AP when its current channel access is finished, i.e., a station generates the backoff time before the collision happens. Thus, IEEE 802.11ah AP is able to schedule stations’ channel accesses based on stations’ registered backoff time to avoid collisions more effectively. Through the use of the Claiming RAW and the registered backoff time mechanisms, IEEE 802.11ah AP can know which stations have high priority’s uplinked data frames and then schedule these stations to have the higher privilege to access the channel. The simulation results shown that. Comparing with the traditional IEEE 802.11ah, the simulation results shown that the proposed Claim-based Priority-Discriminated Channel Access (CPDCA)method has a lower collision rate and higher throughput in the network environment having the higher number of stations in each time slot; the transmission time of those stations with high priority’s uplinked data frames using the CPDCA mechanism is much lower than that of using the traditional IEEE 802.11ah.