A Cross Layer Design for a Multi Hop Self-Healing and Self-Forming Tactical Network

Abstract

Unlike conventional Mobile Ad-hoc Networks (MANETs), tactical networks, which provide communication of software defined radios (SDRs) in mission critical and time sensitive applications, require cognitive functions across the TCP/IP stack to encounter strict con straints while providing smooth incorporation with IP based applications. Tactical applica tions are time and mission critical and thus pose unique requirements for the network, in cluding decentralized control and mission specific latency bounds for end-to-end data delivery. In such applications, bandwidth and delay optimizations are the key goals of communication systems. To cater for the challenges of communication in tactical networks, application specific constrains demand the violation of strict TCP/IP layering, which enables the com munication among multiple layers of stack to develop and deploy customized protocols for optimized performance of the network. This concept leads towards the phenomenon of cross layering design. This thesis proposes a novel Cross Layer Architecture for Application Layer, Network Layer (NET), MAC Layer and Physical Layer (PHY) for a Multi Hop Self-Healing and Self-Forming tactical network for quick call setup, multi-hop routing and collision free data transmission of radios in tactical networks with coordination and cooperation of parameters of four Layers. This cross-layer framework design reduces the call setup time, provides collision-free communication and reuses the empty slots of Time Division Multiple Access (TDMA) protocol which otherwise causes low throughput and large delay. As number of communicating nodes in tactical networks is small as compared to commercial Mobile Ad hoc Networks (MANETs), classical TDMA will yield huge number of empty slots and any Carrier Sense Multiple Access/Collision Detection (CSMA/CD) technique may cause more delay in some critical scenarios. Proposed methodology gives a Cross Layer Architecture for NET Layer and MAC Layer. For this purpose TDMA as MAC layer protocol and Ad hoc On Demand Distance Vector (AODV) as Network Layer Routing Protocol are used. iii The Slot Allocation (SA) Algorithm, Cross Layer TDMA (CL-TDMA) consists of control phase where Ad-hoc on Demand Distance Vector (AODV) control packets are exchanged and data transfer phase where transmission of data and voice occurs. All active radios in vicinity gather information about communicating nodes based on the exchange of control packets by Sodtware Defined Radios (SDRs). The algorithm then uses this information to help all active SDRs find slot(s) that will be used for collision-free transmission. A number of experiments are performed to establish improved performance of the proposed technique compared to other established techniques and protocols. The proposed design is configurable over a set of vital parameters to provide dynamic configurability of critical conflicting factors and optimized performance in different applica tion specific tactical networks. This adds flexibility in the design by tuning it according to the scenario under consideration. This gives an edge on already suggested cross layer designs presented in literature which are application specific and lack the element of uniformity such as cross layer design suggested for optimization of communication delay may not fit the requirement of energy efficiency. A tactical network must support dynamically changing operational priorities. A mathematical model for a cross-layer design is developed, which optimizes trade-offs among different configurations of the SDRs including physical and net working layer to achieve maximum performance in terms of energy efficiency,reliable packet delivery at appropriate data rate and within affordable latency bounds in multi-hop tactical networks. The model is used in a number of mission critical networking scenarios to demon strate enhanced performance where SDRs effectively adapt to the dynamic environment.