Design Of Receiver For The Virtual MIMO In Wireless Sensor Networks

Recently, the Wireless Sensor Networks(WSN) attract many researchers'great inter-ests for its tremendous application potential. However, there exists many challenges todesign a WSN that can satisfy the real requirements of applications. Usually, the WSN ismade up from energy constrained tiny nodes. So, an one of key problems is how to design ahigh energy efficiency transmission strategy.Cooperative transmission technology gives a new direction to resolve the above issue,among which the virtual MIMO is the most attractive. It lets single antenna node cooperatewith each other, constituting a virtual antenna array, and transmit the data as the traditionalMIMO does. This kind of scheme greatly saves the energy of transmission.However, as a part of a complete transmission solution, the performance of the receiverhas significant effects on the whole performance of a transmission. Basing on the previouswork, this thesis lays focus on the receiver design at the data gathering node for virtualMIMO transmission in wireless sensor network.There are following issues in the current research on the receiver:1. The researchers usually assumes that the channel condition, over which the coop-erative MIMO transmission is carried out, is quasi-static, and only utilizes the mostsimple receiver to check the performance of a transmission strategy. The advan-tages of virtual MIMO transmission are not completely utilized.2. The applications, for which the channel are not quasi-static, is numerous, e.g. a?ying plane collects data from a wide monitor area, etc. In these applications,the channel are fast fading. However, currently, there are no receivers have beendesigned for this condition.After conceiving these issues, this thesis designed a uniform transmission form basingon the virtual MIMO, and for this form, the receiver design and optimization are discussedover the quasi-static and fast fading channel conditions, respectively. The contributionsinclude three aspect:1. Proposed a uniform multiple clusters based cooperation form. It combines the ad-vantages of the STBC and the V-BLAST cooperation schemes, and can be config-ured to lay particular stress on either of the schemes. To check the performanceof the new transmission scheme, an algorithm called Gram-Schmidt orthogonaliza-tion based block QR decomposition decoding is proposed. It utilized the orthog- onal structure of the channel matrix, and the complexity of QR decomposition isreduced.2. Proposed a blocking based sphere decoding algorithm and an optimized preprocess-ing. In the new decoding algorithm, the unknown signal vector is firstly split intomultiple blocks, and then, the sphere decoding is applied to each block. It makesthe receiver for quasi-static channel not only has high BER performance, but alsohas low complexity at the meantime. The complexity of the data gathering node isreduced, and the data collecting nodes can complete their tasks with less energy.3. Proposed a sequential Monte Carlo based Bayesian adaptive blind receiver. It canblindly work only with the received signals, and can adaptively track the channel.It makes the virtual MIMO transmission over fast fading channel become possible.The work is supported by:1. the National Natural Science Foundation of China,"Information Processing andTransmission in Re-configurable MIMO based wireless Sensor Networks", No.605720492. the National Natural Science Foundation of China."Key Technology of CognitiveRadio Network",No. 606020293. the Foundation of Hubei Provincial Key Laboratory of Smart Internet Technology,"Key Technology of Cognitive Radio Network", No.HSIT200605...