Modeling TDMA-based USAP in JTRS MDL for multicast and unicast traffic

Abstract

In this paper, we develop loss network models for the hard scheduling mode (virtual circuit mode) of the reservation-based USAP scheduling protocol as used in the Mobile Data Link (MDL) of the Joint Tactical Radio System (JTRS). These models are used to find performance metric estimates for both multicast and unicast traffic. USAP (Unifying Slot Assignment Protocol) is a dynamic distributed resource allocation protocol for mobile multihop wireless networks where the channel is partitioned in time and frequency. MDL creates a backbone sub-network and routes all traffic through this sub-network. For the backbone sub-network, we consider algorithms that form Connected Dominating Sets. We use loss network models that couple the physical, MAC, and routing layers effects. The effect of the MAC layer is modeled by approximating available capacity at a node. The available capacity to transmit is computed based on the USAP reservation rules and the node's 2-hop neighborhood traffic. For a given time varying scenario, we compute the performance metrics of blocking probability and throughput for both multicast and unicast traffic as a function of time. We compare the results of our model against simulation.