A Packet Scheduling Technique Based on (m, k)-Firm Guarantees for Differential Quality of Service in Tactical Ad-Hoc Networks

Tactical ad-hoc networks must provide differentiated Quality of Service (QoS) for heterogeneous traffic, yet classic AODV’s single-queue FIFO forwarding cannot prevent priority inversion or starvation under load. We propose a packet scheduling scheme that enforces stream-level (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m, k</i>)-firm constraints and uses Distance-Based Priority (DBP) to raise the urgency of flows that are close to violating their (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m, k</i>) requirement, with EDF then FIFO tie-breaking at dequeue time. The scheduler updates per-flow <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i>-sequences online and selects the head-of-line packet from the stream with the smallest DBP distance. We evaluate the scheme in ns-3 against RL-AODV and FP-AODV under three tactical scenarios (Mountainous Terrain, Urban CQB, and Landing Operation) using AODV and eight traffic classes. Across all scenarios, FP-AODV maximizes PDR for top classes but severely starves low classes, while RL-AODV yields uniform but mediocre service. In contrast, the proposed (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m, k</i>)-firm scheduler preserves high PDR and low end-to-end delay for the highest priorities while preventing starvation and lifting the PDR floor for low priorities, particularly in NLOS and many-to-few aggregation topologies. Throughput trends mirror PDR, and end-penalized delay remains bounded for lower classes. The scheduler operates with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O(N ·k)</i> complexity for N streams and window size <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i>, making it practical for resource-constrained nodes (e.g., <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>=100, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i>=15). Deadlines are assigned per traffic class for consistent meet/miss evaluation across hops, and each flow is tracked independently through metadata. In addition, it incorporates an adaptive routing-level load balancing mechanism that refines AODV’s path selection in real time using delay, queue, and PDR metrics, while maintaining full protocol compatibility. These results demonstrate that (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m, k</i>)-firm scheduling provides a tunable balance between differentiated service, fairness, and adaptability for tactical MANETs.