Reliability and scalability evaluation with TCP/IP of IEEE802. 11ah networks
In Europe, devices operating in the license-free 868MHz ETSI SRD band must comply with a maximum duty cycle limit of 2.8%, provided that they also support Listen Before Talk (LBT) and Adaptive Frequency Agility (AFA) features. Further, in scenarios where reliable bidirectional traffic is required, such as firmware updates over the air, it is a natural choice to use TCP. In spite of duty cycle limitations and given the fact that IEEE 802.11ah supports high data rates up to 7.8Mbps, TCP-based scenarios become more realistic. Therefore we evaluated the feasibility of bidirectional TCP traffic on top of 802.11ah in two scenarios: a reliable throughput scenario that analyses which configurations have the best attainable throughput, and a high scalability scenario where we push the limits of the number of stations the network can support. In order to accurately model bidirectional traffic, we have expanded the existing ns-3 802.11ah module. Both changes to the module and preliminary performance results are presented.