Path error-aware RTO design for smart meter data traffic in IEEE 802.11s-based AMI networks

Advanced Metering Infrastructure (AMI) applications for Smart Grid (SG) typically employ wireless mesh based data collection approaches that collect smart meter data via multi-hop routing. One of the mesh-based solutions that is viable to use is the IEEE 802.11s wireless mesh standard. However, when TCP is employed in this standard for periodic smart meter data collection, the performance starts to degrade due to classical congestion mechanism of TCP which is falsely triggered due to the link failures. The main reason for frequent link failures is the occurring of collisions among beacons sent by the Peering Management Protocol (PMP) of IEEE 802.11s standard to maintain link connectivity among the smart meters (SMs). This in turn causes doubling of the retransmission timeout (RTO) of TCP assuming that there is congestion and thus introduces extra overhead and packet delay. In this paper, we propose a cross-layer approach to inform the transport layer about the link failures happening at the MAC layer. To this end, path error information from the routing protocol of IEEE 802.11s is exploited. The idea is to eliminate the unnecessary doubling of the RTO timer when there is a link failure. We evaluated the proposed mechanism through simulation using ns-3 simulator. The results indicate that significant network performance improvement in terms of end-to-end delay and collection time can be achieved by employing our approach. The simulation results also show that further improvement in collection time can be achieved when an upper bound limit is enforced for the RTO timer.