【作者】 陈丹；

【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， 2013， 博士

【摘要】 Ad Hoc网络无需固定基础设施的支持，能够灵活组网，具有诱人的应用前景。然而，在具有便捷、低成本组网等优势的同时，这种高度灵活、可控资源丰富的网络也为技术的实现带来了严峻的挑战。Ad Hoc网络涉及的关键技术非常广泛，目前仍存在着诸多需要彻底研究的问题。媒体接入控制(MAC)协议主要解决网络节点如何接入共享无线信道的问题，因此直接影响网络节点的传输效率。MIMO技术引入Ad Hoc网络为网络带来了新的可利用资源，然而，其也对MAC协议的设计提出了新的要求。本文中研究了Ad Hoc网络中支持MIMO的媒体接入控制协议，主要的内容和贡献包括以下几个方面：(1)基于PRP MAC，结合动态分配预约型协议提出了一种预约与竞争相结合的MAC协议FPR-PRP MAC。FPR-PRP MAC采用同步的时间结构，通过五阶段预约使网络节点获得传输时隙号。在信息时隙，根据预约的结果，一部分节点可以优先发送RTS分组，其它节点再通过竞争发送RTS分组。接收节点根据收到的全部RTS决定允许各发送节点使用的数据流数目，并将此允许值携带在CTS中回复给发送节点。FPR-PRP MAC将预约与竞争相结合的机制减少了网络中RTS冲突，同步的时间结构消除了控制分组和数据分组的冲突，因此可以有效增加网络中流控方式发送的分组数，并提高网络吞吐量。(2)针对采用MIMO链路的Ad Hoc网络，提出了基于协议线程化技术的节点激活型拓扑未知多址接入协议MIMO-T-TTMA，并理论分析了MIMO-T-TTMA协议的吞吐量。MIMO-T-TTMA由一个时间扩展多址接入协议和一个时分多址接入协议以时间共享的方式组合而成。在分配的时隙中，节点通过与目的节点交互RTS/CTS分组来确定传输的数据流数目；而当RTS/CTS交互失败，节点依一定概率发送1个数据流。对于未分配给节点的时隙，节点也依概率发送1个数据流，以提高时隙利用率。MIMO-T-TTMA消除了节点移动引起网络最大度变化时某些节点无法成功传输的问题，且在节点度较大时具有较高的吞吐量，适用于拓扑经常变化的Ad Hoc网络。(3)针对采用MIMO链路的Ad Hoc网络，提出了链路激活型拓扑未知多址接入协议MIMO-LATTMA。MIMO-LATTMA利用正交拉丁方来为网络链路分配传输时隙，保证每个链路在1帧中至少有1个时隙可以成功传输。同时推导了MIMO-LATTMA的平均吞吐量，并以最大化平均吞吐量为准则给出了选择协议参数的方法。理论结果表明，MIMO-LATTMA协议可以提高网络节点的吞吐量。(4)针对采用MIMO链路的Ad Hoc网络，提出了充分利用MIMO空间复用能力的集中式TDMA协议E-MIMO-CTDMA。该协议通过在初始时隙分配中考虑MIMO的空间复用能力而有效地减小了调度帧长，通过允许节点发送多个数据流而高效利用了MIMO的空间复用能力。推导分析了E-MIMO-CTDMA的吞吐量和时延性能，结果表明，E-MIMO-CTDMA可以提高网络的吞吐量，减小网络的平均时延和最大时延。(5)提出了一种适用于MIMO链路Ad Hoc网络的分布式自适应TDMA协议MIMO-DATDMA，该协议充分考虑MIMO空间复用，合理地为节点分配时隙和数据流，保证网络拓扑不发生变化的情况下实现无冲突传输；而当有新节点加入或网络节点移动引起网络拓扑发生变化时，协议能够利用MIMO带来的空间自由度，快速发现拓扑变化，并根据网络局部拓扑和时隙信息的交互动态调整节点时隙和数据流数，使网络尽快恢复到无冲突的状态。仿真结果表明，MIMO-DATDMA能充分利用MIMO带来的优势，显著减小网络调整时隙和数据流等参数需要的时间，使网络快速恢复无冲突状态。更多还原

【Abstract】 Ad Hoc networks do not need the support of any fixed infrastructure and can groupnetworks flexibly, thus is promising technology for future communication networks.However, with the advantage of flexibility and low cost, Ad Hoc networks still faces severechallenges in technical realization. As the key technologies related to Ad Hoc networks arecomprehensive, there are quite a number of problems that are open. Among the keytechnologies, Media access control(MAC) protocols mainly solve the problems ofaccessing the sharing wireless channel, and its performances directly affect the transmissionefficiency. The introduction of Multiple Input Multiple Output(MIMO) technology to AdHoc networks has brought new resources and put forward some new requirements for thedesign of MAC protocols. In this thesis, we study the MAC protocols for Ad Hoc networkswith MIMO technology, and our main contributions are as follows:(1)Combing the contention-based protocol PRP MAC and reservation based protocolFPRP, a hybrid protocol FPR-PRP MAC is proposed. FPR-PRP adopts a synchronous timestructure, and allows the nodes acquire transmission slot numbers through five phasereservation. Then in information slots, some nodes can transmit RTS packets with higherpriority according to the reservation results, and other nodes contend with each other totransmit RTS packets. A receiving node determines the maximum allowable number of datastreams according to all the RTS packets it received, and put this number in the CTS packetto reply the transmitter. The mechanism of combing reservation with contention inFPR-PRP MAC reduces the collisions of RTS packets in the network. Moreover, thesynchronous time structure eliminates the collisions of control packet and data packet.Therefore, the proposed FPR-PRP MAC can transmit much more packets instream-controlled way, and increase the network throughput.(2) Based on protocol threading technique, a node activation topology-transparentMAC MIMO-T-TTMA is proposed for MIMO link Ad Hoc networks. It combines a timespread multiple access protocol and a TDMA protocol in time-sharing mode. The nodes inthe networks determine the number of data streams to be transmitted through exchange ofRTS/CTS packets. When RTS/CTS exchange fails or in non-assigned slots, the node also transmits one stream according to some probability, with the expectation of improving theslots utilization. MIMO-T-TTMA eliminates the transmission failure when the networksmax degree increases, moreover, it has higher throughput when max degree is relativelylarge, thereby it adapts to Ad Hoc networks with changing topologies.(3) A link activation topology-transparent MAC MIMO-LATTMA is proposed for AdHoc networks with MIMO links. The protocol allocates transmission slots for each link inthe networks based on the theory of orthogonal Latin squares, so that each link cansuccessfully transmit its data streams in at least one slot in a frame. The average throughputof the protocol is deduced through theoretical analysis. To maximize the averagethroughput, a method of searching the optimal protocol parameters is also derived.Numerical results show that, MIMO-LATTMA can increase the throughputs of networknodes.(4) A centralized TDMA protocol E-MIMO-CTDMA is proposed for MIMO link AdHoc networks, which can make full use of MIMO spatial multiplexing(SM) to improve thenetwork performances. Specifically, by utilizing the SM in the initial slot allocation phase,E-MIMO-CTDMA can reduce the scheduling frame length. Moreover, allows networknodes to transit more streams in a slot further exploit the SM thoroughly. The throughputand delay of E-MIMO-CTDMA are derived via the theoretic analysis. Evaluation resultsshow that, E-MIMO-CTDMA can increase the network throughput and reduce the averageand maximum delay.(5)A distributed adaptive TDMA protocol MIMO-DATDMA is proposed for MIMOlink Ad Hoc networks. By carefully considering MIMO SM and reasonably allocating slotsand streams for each node, MIMO-DATDMA can ensure collision-free transmission for allthe nodes when network topology dose not change. While new nodes’ appearance or nodes’mobility changes the network topology, MIMO-DATDMA can quickly discover thetopology changes, and adjust the slots and streams of a portion of nodes, evenly making thenetwork resume the collision-free state. Simulation results show that, by making full use ofthe MIMO’s advantages, MIMO-DATDMA can evidently reduce the time needed foradjusting the network parameters.更多还原