Effects of link rate assignment in IEEE 802.11 mesh networks

The IEEE 802.11 standard supports a variety of modulation and coding schemes (MCSs). In 802.11-based wireless mesh networks (WMNs) it is hence possible to adapt the link rate to the channel conditions. In particular, smaller link rates may be accepted for an increased spatial reuse. In an earlier study, we showed that this effect is suitable for increasing the max-min fair share throughput in a WMN operating with a TDMA channel access scheme. In this work, we investigate if the use of smaller link rates is also suitable for increasing the throughput of a WMN using a contention-based channel access mechanism. For this purpose, we analytically derive a guideline for link rate assignment as protection against hidden nodes and compute the costs and benefits of this mechanism in terms of MAC layer efficiency. A simulation study shows however that in a medium-sized WMN this strategy is less advantageous than assumed and allows to give advices for practical mesh network deployments.