Study On Key Technology For Tactical Mobile Ad Hoc Networks

Tactical communication is one of the most primary application backgrounds for Mobile Ad Hoc Networks. Future war is composed mainly of Networks and Information, which rapidly expand scale of communication system and information transmitted between nodes. High bandwidth is useful because it supports increased capacity, high volume data exchange, short delays, and high assurance of connectivity. Bandwidth has become increasingly critical.Mobile Ad Hoc Networks is a complex system and the research work in this dissertation carries a deep study on new techniques of Mobile Ad Hoc Networks that will continue to increase available bandwidth. There are still some key technologies need to be solved to make the MANET's work efficiently, all of the above problems are reflected in the following aspects in network designing, including physical layer, Media Access Control (MAC) layer, network layer, application layer, QoS management, network security, etc. In this dissertation, we focus mostly on the OFDM technology in physical layer, scheduling technology and directional antenna in MAC layer, and the main contributions are listed as the following:1)A full OFDM system, based on the study of wireless tactical channel and key technology of OFDM, is designed and realized. The paper Propose improved channel estimation and tracking algorithm for tactical OFDM system in frequency domain. The results of both theoretical analysis and simulation show that the proposed algorithm possesses all impressive performance with less system overhead and lower computation burden than conventional algorithms.Considered the characteristic of tactical communication and the feasibility of system hardware, the paper proposes synchronization and PAPR reduction scheme with low complexity. Simulation including code and modulation, channel estimation, synchronization and PAPR show that all of the schemes are well solved the difficulties. The hardware platform demonstrates that the proposed method performs well at typical mid-wave and short-wave broadcasting channel and it is easy to implement.2) Based on SUI channel and ITU channel model, the paper studies the performance of adaptive MIMO-OFDM system under tactical communication environment. The simulations include system performance under different terrain, influence of antenna correlation on system capacity and system performance under spectrum efficiency. Simulation results under static state show that the bit error performance of system which provides more diversity gain is much better. And the performance of system under complex terrain is much better.3) To improve the channel throughput of IEEE 802.11 protocol with the Binary Exponential Back-off algorithm (BEB), we propose a novel BEEB algorithm (Binary Exponential Exponential Backoff),which the Back-off time obeys the exponential distribution and the idea of active nodes. BEEB algorithm has the following characteristics: simplicity, integrability, complete distribution. The BEEB algorithm can effectively improve the default that nodes choose long defer time and access the channel slowly, and can shorten the idle time and decrease the time to acquire the channel by accelerating the collision process. Results show that the BEEB algorithm can decrease the collision times, provide higher channel utilization and a lower network load compared with IEEE 802.11 DCF protocols.4) For directional antennas application in Mobile Ad Hoc Networks, a novel Directional Network Allocation Vector-based Packets Scheduling (DBPS) algorithm is proposed. The algorithm divides the surrounding region of the node using the DNAV parameters, and secondly eliminates the region that is not available, and lastly chooses the ideal destination node to send the packet. The DBPS scheme can enable a higher throughput while effectively solving the HOL blocking problem. The computer simulation and performance analysis give farther proof that the DBPS algorithm is effective and reasonable.5) Based on the Chapter 5, the article designed the EDRP routing protocol, which is support the directional antenna. The direction of antenna for mobile Ad Hoc networks generated velocity switch, radio, overhead and other issues, using the beam mark, timer, and improved routing maintenance to reduce the impact of such means. At the same time, the paper takes into account not only the direction of the antenna, but also taking into account the mobile Ad Hoc networks are two important factors-the survival of life of the network and network load balancing, and improve the routing strategies of the EDRP protocol, and the use of a delay in forwarding the request routing strategy, and give the direction of an antenna in support of the load-aware mobile Ad Hoc network routing protocol (LEDSR). LEDSR protocol considers total path information between source node and destination node as the primary route selection metric while discovering and maintaining route, the network load is balanced by avoiding the congestion path.