Abstract
The IEEE 802.11ax standard, which realizes multi-user transmission based on orthogonal frequency division multiple access (OFDMA), has been highlighted as a key technology to meet high future demand for Wi-Fi systems. Since this standard is still being developed, performance analysis through mathematical modeling is of paramount importance; however, existing studies have several limitations. Firstly, most of these consider only the saturation network throughput, whereas for 802.11ax in particular, the access delay of the nodes needs to be studied carefully, since they no longer acquire the medium independently but depend solely on the access point’s (AP’s) schedule. Secondly, since the network performance may be affected to a greater extent by legacy nodes than by 802.11ax nodes, it is desirable to consider various heterogeneous cases of networks with existing legacy nodes. In this paper, a new analytical framework for the 802.11ax MAC protocol is provided. Markov-chain-based models are developed to represent the behavior of the 802.11ax nodes, and both non-saturated traffic conditions and co-existence with the legacy nodes are considered. Through both analysis and MATLAB simulations, it is shown that the proposed model accurately evaluates the throughput and the delay performance under various network conditions.
Highlights
Wi-Fi has emerged as a key off-loading technology to alleviate the data explosion in cellular networks, since it provides many advantages such as ease of installation, free Internet access, and high data rates
IEEE 802.11ac [2], the first Wi-Fi standard supporting MU transmission based on multi-input multi-output (MIMO) technology, has been developed and deployed, but this has several disadvantages that greatly limit the gain in MU transmission, such as a high channel state information (CSI) acquisition overhead [3] and lack of MU transmission in the uplink (UL) direction
The 802.11ax functionalities related to orthogonal frequency division multiple access (OFDMA) MU transmission, such as resource units (RUs) contention, buffer state request (BSR), and trigger frame’ (TF), are implemented in the simulator on top of the legacy distributed coordination function (DCF)
Summary
Wi-Fi has emerged as a key off-loading technology to alleviate the data explosion in cellular networks, since it provides many advantages such as ease of installation, free Internet access, and high data rates. It triggers the actual UL transmission by the STAs by broadcasting a ‘trigger frame’ (TF) to the network This results in 802.11ax STAs having access to the channel in a completely different way from existing legacy nodes, and in unavoidable changes to the MAC layer. To properly analyze both the delay and the throughput, a more realistic traffic model should be used Most of these studies do not consider the issue of co-existence with non-802.11ax STAs. 802.11ax will soon be launched on the market, it is impossible to expect that all wireless devices will be equipped with 802.11ax functionality; instead, it is very likely that 802.11ax and legacy devices will co-exist for a very long time.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
