Automatic repeat request (ARQ) over TDMA-based mesh network

The use of automatic repeat-request (ARQ) over a mobile ad-hoc network (MANET) presents unique challenges in handling signaling, connection identification, and implementation. This paper describes the implementation of a selective-repeat ARQ protocol in a mesh MANET called mesh-enabled tactical adaptive - MANET (METAMANET). The mesh MAC operates over the 802.16d physical (PHY) layer. The implementation of this ARQ protocol follows the specification described in the IEEE 802.16 standard with unique adaptations for mesh operations. Our implementation preserves the opportunity for future interworking with standards-based devices to the greatest extent possible. We hypothesized that adding ARQ would improve throughput and reduce loss rates. We present the results of lab testing of radio implementations of the ARQ-enhanced META-MANET protocol in RF-cabled with emulated loss and mobile outdoor wireless environments. This testing is analyzed for topologies of two nodes to eight nodes and the emulation of various dynamic mobile topologies across terrain and obstructions. The impact to application traffic packet loss rate, throughput, latency, and multi-hop throughput are analyzed and presented. Several controlled scenarios were performed, with and without ARQ, to compare the performance of our implementation. We found that the implementation of ARQ over the mesh yielded significantly improved throughput, as perceived by the application, under many conditions. Overall, this study demonstrates the feasibility of implementing a standardized ARQ mechanism over a mesh topology in high-bandwidth environments with multiple nodes in a moving topology.