Research On Routing Protocols And QoS Routing Algorithms For Tactical MANETs

Tactical MANET is a non-centralized, self-organized tactical communication network which composed of many tactical radio transceivers, and it is a kind of end-subnet of tactical internet which has the most communication nodes and covers the largest scope. Tactical MANET is a typical application of mobile ad hoc networks in the digital battlefield. As the flexibility of networking, rapid deployment and high-survivability features, tactical MANET is especially suitable for the transmission of combat command and battlefield control information, hence the demand for the development, improvement and deployment of tactical MANET becomes more and more urgent.In tactical MANET, the efficient and reliable routing protocol architecture is the prerequisite and basis to ensure the success of communications in the network, and it is the most important issue for the establishment of mobile ad hoc networks. Research on routing protocols is one of the major focuses in tactical MANET’s literature and has many difficulties, especially for the tactical MANET. In the future, tactical MANET has faster changing topology and diversity of services, nodes in the network must keep up with the changes of the structure quickly, the requirements for fast networking and reliability are higher then ever before, thus the design of routing protocols faces more severe challenges.The development trend of digital warfare decide that the services over future tactical internet will become more and more complex and comprehensive, information transmitted over the network is no longer a single voice or command or control instructions, the network must support the integrated transmission of battlefield situation information, battlefield reconnaissance video, battlefield images, multimedia real-time conferencing data, etc. To ensure stable and reliable transmission of multimedia data, as the end-net of the tactical internet, the tactical MANET must provide the appropriate quality of service(Qo S) for different services, and Qo S routing technology is the key issue of Qo S guarantee in tactical MANET. The study on Qo S routing technology is facing many difficulties and challenges at this stage.Based on above application backgrounds, this paper analyzed a large number of research literatures, made a systematic and in-depth research on routing protocols and routing Qo S guarantees for tactical MANET, and obtained some innovative achievements on the following aspects:(1) Proposed an optimized AODV routing protocol based on reverse route search in leisure time and route learning mechanism.This paper first analyzed the limitations of standard AODV routing protocol, then put forward the reverse route search mechanism in leisure time and neighbor’s route learning mechanism without increasing any other hardware and node’s processing load. Utilizing these two mechanisms to optimize the standard AODV protocol, an optimized AODV protocol ─ O-AODV was presented. O-AODV can produce a number of local routes, thereby increases the route redundancy in the network, improves the efficiency of route discovery and accelerates the local routing-failure repair. Simulation results show that, O-AODV can improve packet delivery ratio and decrease the end-to-end packet delay, effectively reduce the network overhead of re-routing, its performance is superior to AODV in large scale and fast changing MANETs.(2) Utilizing the group movement characteristic of tactical MANETs, this paper designed an adaptive hybrid routing protocol based on the stability of neighbors.According to the construction characteristics and mission requirements of tactical MANETs, this paper analyzed the group movement behaviors of nodes in tactical MANETs, and used the stability of neighbors to achieve the automatic identification between groups. On this basis, this paper designed two routing states for all nodes in tactical MANETs: table-driven routing state and on-demand routing state, and then proposed an adaptive hybrid routing protocol ─NS-AHRA. NS-AHRA uses table-driven routing protocol in a stable group and on-demand routing protocols between groups, and takes full advantages of these two kind of routing protocols, thus NS-AHRA can achieve small routing delay and low routing overhead. Simulation results show that, NS-AHRA protocol has better packet delivery ratio, moderate end to end delay and smaller routing overhead, its performance and routing efficiency are better than pure table-driven routing protocols or on-demand routing protocols.(3) Proposed multi-constraint Ant Colony Optimization Qo S routing algorithm based on multi-state transferring strategies.This paper analyzed the multi-objective, multi-constraint Qo S routing model of tactical MANETs, and introduced ant colony optimization algorithm to solve the tactical MANETs’ Qo S routing problem. To improve the efficiency of ant colony optimization Qo S routing algorithm, reduce latency and network overhead, this paper presented multi-state transferring strategies and resource reservation mechanism while routing, further more proposed a novel ant colony optimization Qo S routing algorithm ─ MTS-AQRA. MTS-AQRA integrates link’s stability and route’s congestion into conventional Qo S requirements while routing. By utilizing the diversity of route-search ants and the concurrent route-searching result from multiple transferring processes, MTS-AQRA can work rapidly and effectively to establish stable routes which satisfy the Qo S requirements of certain services. Simulation results show that MTS-AQRA outperforms AODV, Qo S-Aware ACO and Ant Hoc Net in terms of packet delivery ratio, end-to-end delay and route stability.(4) Proposed an adaptive hybrid Qo S routing algorithm which integrates group characteristics and priority scheduling mechanism into the tactical MANETs’ Qo S routing.Considering the group characteristics of tactical MANET and the priority differences between services over the network, this paper designed a service scheduling routing mechanism which can search routes with different priority according to the service grade, and proposed an adaptive hybrid Qo S routing algorithm suitable for tactical MANETs ─ HQRA. HQRA adopts table-driven Qo S routing within the stable group, and on-demand ant colony optimization Qo S routing between groups. To meet the transmission requirements of the services in the tactical MANETs, HQRA adopts differential scheduling route process according to services’ grade level and the priority of Qo S requirements. Simulation results verify that HQRA can achieve differential routing in accordance with different services’ priorities, which ensures high grade level service has the priority to use network resources; while for transmission of single service in tactical MANETs, HQRA outperforms conventional routing algorithms because HQRA integrates group characteristics and differential scheduling features into routing procedure, it can meet the needs of Qo S routing in tactical MANETs.(5) Based on embedded ARM hardware platform, the Wi-Fi wireless network technology and the embedded Linux operating system, this paper designed and developed a MANET test bed, and made a series of physical simulation experiments and performance comparison study of the proposed routing algorithm in the test bed.In order to verify the performance of the routing algorithm in the physical environment, a Wi-Fi handheld MANET terminal based on ARM technology was developed. An embedded Linux operating system and a Wi-Fi wireless network card driver was transplanted for this MANET terminal, and a variety of routing algorithm driver programs as well as network performance testing software were designed and transplanted too. Using many handheld MANET terminals, a MANET test bed that deployed in actual network environment was built, and many physical simulation experiments were made based on the MANET test bed to verify the performance of the routing algorithms proposed in this paper.