Efficient Multi-Channel Medium Access Control Protocol for SDR-based Tactical Wireless Networks

Abstract

The thesis proposes a novel concept in which SDRs (Software Defined radios) of a tactical network are confined into dynamic self-regulatory virtual sub-nets. The proposed design eradicates conflicts in resource access and distribution using a hybrid of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) approaches. It maximizes the usable bandwidth by exploiting radios’ autonomous behavior and comply simultaneous data transmissions in a multi-channel environment with self-organizing and self-forming capabilities. In compliance with low latency transmissions, the thesis presents (i) Request-Acknowledgement-Request (RAR) and (ii) Optimized RAR (O RAR) schemes to communicate intended data transmissions, sub-nets formation, and dynamic data slot allocation with control phase optimization. The subnets based design extends to devise a novel Virtual Sub-nets based Cross-Layer MAC (VSCL-MAC) protocol. The proposed MAC-centric design with cross-layer optimization empowers routing with persistently available k-hop neighbors and route information. The integration of SDR capabilities and cross-layer optimization mitigate explicit use of higher layer functionalities for efficient multihop routing and escalate network throughput. The thesis provides a practical implementation of designs using a timeslotted common control channel for nodes’ coordination and collision-free multi-channel data transmissions. The theoretical findings with experimental analysis demonstrate the gains of virtual sub-nets in tactical networks. The results and analysis over extensive simulations validate significant performance improvements in terms of minimum control overhead, effective multiple transmissions coexistence with an increase in network throughput, and reduced data latency. Furthermore, a hybrid collision-free MAC is proposed that utilizes the opportunistic full-duplex transmissions to achieve better throughii put and reduce latency in a single-channel environment. Considering Mobile Ad hoc Network (MANET) environment, radios face precipitous connectivity that causes substantial packet loss and degradation of network performance. The thesis presents a stochastic distribution based model for mobile SDRs that analyzes the network connectivity ratio required by an application and estimates control time (e.g., packet forwarding and route discovery) to maintain QoS for time-sensitive and reliable data requirements. The proposed protocols maximize the network throughput by enabling the coexistence of transmissions among multiple SDRs. Thus, providing more power to the users for next-generation applications, delivering reliable transmission, QoS, affordable latency bounds for time-critical and high data rate applications. Moreover, the proposed designs distinctively provide a seamless self-forming self-healing MANET networking capability where SDRs effectively improve data performance, connectivity, and operational efficiency in a dynamic environment under the readiness of existing communication architecture.