Study On Cooperative MIMO Transmission Scheme For Clustered Ad Hoc Networking

Mobile ad hoc networking, which is usually multi-hop and autonomous, consists ofa group of mobile transceivers acting as both routers and terminals. Decentralization,self-organization, dynamical topologies, multi-hop routing, bandwidth constraint,limited security, asymmetrical channels and the peculiar mechanisms of sharingchannels, jointly call for special considerations when designing transmission schemesfor mobile ad hoc networks. The creatively proposed cooperative communication canexploit the spatial diversity gain produced by nodal dispersity, where multiple wirelessnodes cooperate to share channel resources to form virtual multi-antenna system.Multi-node cooperation is capable of fighting fading effects of wireless channels andboosting system performance dramatically with improved channel capacity, shortenedend-to-end delay, reduced transmission energy and decreased bit error rate.Centering on mobility, clustering algorithms and cooperative MIMO transmissionstrategies for mobile ad hoc networks, the dissertation investigated a cooperative MIMOtransmission scheme, which was applicable to clustered mobile ad hoc networkscharacterized by random way mobility (RWM) and reference point group mobility(RPGM). The major research and achievements of the M. S. dissertation include:1) The principle features and the involved key technologies of mobile ad hocnetworks were summarized. Grounded on the nature of cooperative communication andsome commonly used cooperative relay protocols, cooperative gains were derived forcooperative communication systems employing amplify-and-forward (AF) relaying anddecode-and-forward (DF) relaying. Fundamentals of multi-relay cooperativetransmission and virtual-MIMO-based hierarchical cooperation protocols were analyzed.Moreover, the dissertation studied the performance gain achieved by distributed space-time coding.2) In accordance with RWM and RPGM models of mobile nodes in ad hocnetworks, two multi-parameter weighted clustering algorithms were proposed. The firstalgorithm took into account the residual energy, the number of neighbor nodes and therelative stability of a node, which went for networks with RWM. The second oneconsidered the residual energy, the number of neighbor nodes and the mobilitycorrelation of a node, which run well in networks with RPGM. Simulations comparedthe proposed algorithm with MOBIC and HD clustering algorithms. 3) A cooperative MIMO model applicable to clustered ad hoc networks and thecorresponding cooperative-node-selection algorithm were proposed. Wherein, thealgorithm synthesized the state of asymmetrical bi-direction channels, the residualenergy and the connectivity of a node. Mechanisms of cooperative-nodes-selection andvirtual links establishment as well as maintenance were designed. Furthermore, somecooperative relaying schemes were inquired. Finally, simulations validated thesignificance of the proposed cooperative MIMO transmission scheme for clustered adhoc networks with respect to system capacity and energy efficiency.