【作者】 张光辉；

【导师】 李建东；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2006， 博士

【摘要】 Ad hoc网络是一种非常具有发展潜力的网络,也是一个复杂的系统,所涉及的研究内容非常广泛,目前仍然存在一些需要彻底研究的问题,新的应用也对它的研究和发展不断提出新的挑战。另一方面,通信和微电子技术的迅速发展又为Ad hoc网络的发展创造了新的契机。本文从Ad hoc网络研究领域中的研究热点出发,分别研究了多跳Ad hoc网络中的拓扑未知预约时分多址接入、支持MIMO的时分多址接入、支持智能天线的时分多址接入以及临界传输半径等问题。本文的主要内容和贡献包括以下几个方面:1.深入研究了多跳ad hoc网络中时分多址接入技术。将拓扑未知时分多址接入协议和预约相结合,提出了拓扑未知预约时分多址接入协议TTR-TDMA。该协议基于时分多址的帧结构,每个时隙分为预约阶段和数据传输阶段。每个节点在其分配的时隙,通过预约的方法占用时隙以解决可能的冲突;并且在其未分配时隙通过载波侦听来竞争使用该时隙。通过理论分析我们推导出网络的最佳性能及其最佳参数。并且我们通过仿真验证了我们的理论分析。网络拓扑和业务负载对通过率的影响也在本文加以研究。仿真结果表明该协议具有稳定性和公平性。此外,该协议的性能也优于其他拓扑未知协议。2.基于当前支持MIMO的多址协议需要知道全网拓扑,本文将TTR-TDMA与MIMO相结合,提出了适合多跳ad hoc网络的支持MIMO的拓扑未知预约时分多址接入协议MIMO-TTR。MIMO-TTR同样不需要知道全网的拓扑信息,并且通过平衡MIMO链路的传输容量和抗干扰能力来分解冲突。当一个时隙仅被一个用户占用时,该用户可以以最大传输速率占用该时隙。当一个时隙必需由多个用户共享时,我们可以减小每个用户的数据速率,并增强它的抗干扰能力,以使这些用户可以同时成功地发送减小速率后的数据流。因为该协议不需知道全网的拓扑结构,因而便于实现和适合于分布式应用。通过理论分析我们推导出节点最小通过率及最佳帧长。3.针对当前支持MIMO的多址协议仅支持点对点传输,本文提出多跳Ad Hoc网络中支持MIMO的广播传输时分多址接入协议,其核心算法是保证每个节点无冲突传输广播业务且保证最小帧长的时隙调度算法。该算法充分利用了MIMO系统并行数据流传输的特性,该特性可使发生传输冲突的节点集可能由两跳范围内的邻节点减小到一跳范围内的邻节点,从而提高网络容量。结果表明该协议可以较大地提高网络容量和减小平均分组时延。更多还原

【Abstract】 Ad hoc network is a self-organizing and self-configuring multihop wireless network without predefined infrastructure where the network topologies, transfer model and channel environment dynamically change with node mobility. Despite the long history of ad hoc networks, there are still quite a number of problems that are open. With the development of communication and electronics, ad hoc network faces a new chanllenge. The main research production of this dissertation is as follows:1. Unlike the current topology-dependent schedules, the efficiency and robustness of topology-transparent schedules are invulnerable in mobile ad hoc networks. In this paper, a topology-transparent time division multiple access (TDMA) with reservation is proposed for multi-hop ad hoc networks. The protocol is based on slotted TDMA architecture in which every slot is divided into reservation phase and data transmission phase. Each node resolves collisions by reservation in its assigned slots and utilizes free slots among its non-assigned slots through carrier sense. Through theoretical analysis, we derive the optimal parameter for the best performance. We testify our analysis by simulation and the influence of network topology and traffic load on the throughput is also invested. Simulation results also show that the protocol has stability and fairness. It is better than other topology-transparent schedules.2. To effectively combine ad hoc networks with multiple input multiple output (MIMO), distributed topology-transparent reservation for time division multiple access (TDMA) protocol with MIMO links in multihop ad hoc networks is proposed. By Galois Radio Network Design (GRAND), the protocol assigns each node slots in each frame and need not know the whole network topology information. As a result, the overhead to collect topology information is greatly reduced. By reservation each node simultaneously transmits all data streams in the MIMO link in its assigned interference-free slots and utilizes its shared slots with other nodes to transmit a part of all data streams in the MIMO link to resolve collisions. The guaranteed throughput and optimal frame length are also derived. Results show that the network throughput will be improved greatly by dynamically allocating MIMO transmission capacity and its anti-interference ability.3. As the current medium access control (MAC) protocols with multiple input更多还原