【作者】 张雪芬；

【导师】 乐光新； 尹长川；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2011， 博士

【摘要】 以物联网为代表的信息革命的第三次浪潮己悄然来临并正在改变人们的生产和生活方式。无线传感器网络(Wireless Sensor Network, WSN)技术可以使物联网能够达到全球互联和随时随地与任何人和物通信的能力,引起了信息技术研究领域的广泛关注。无线传感器网络是一个资源受限、无线多跳传输、单节点易毁的自组织网络,通过多个节点的有效组织、协作工作可以提升网络整体性能。论文以基于无线传感器网络的多节点协作研究为主题,重点研究了无线传感器网络的分布式估计和协作传输技术。论文具体研究内容和结论如下：1.针对并行分布式无线传感器网络结构,建立了基于最小均方误差准则的节点分布式参数估计模型,以优化该模型估计值的均方误差为目标,提出了一种有效的节点选取和相应的功率分配算法(OPA),并分别对总功率受限以及总功率和单个节点功率受限两种情形进行了分析和仿真。仿真结果表明,在给定中断概率条件下,论文提出的功率分配算法优于传统的等功率分配算法。2.针对分簇式无线传感器网络结构,建立了基于最大似然准则的估计模型,提出了一种簇内分布式参数估计算法。该算法通过簇头和各节点进行信息交换,迭代完成参数估计,避免了普通节点和汇聚中心的信息传输,减轻了汇聚中心的信息处理量。理论分析表明,算法迭代过程最终收敛到最大似然估计值。此外,该算法易于划分成若干子任务进行并行处理。仿真结果表明,该算法在中高信噪比条件下,具有快速收敛的优点。3.研究了基于放大转发(Amplify-and-Forward, AF)技术的分簇式无线传感器网络协作传输问题。分析了结合AF技术的两跳分簇式无线传感器网络的传输性能,利用母函数推导了对称及非对称多种中继状态下,目的端采用最大比合并准则的瞬时接收信噪比概率密度函数的表达式,并在此基础上给出了遍历容量的精确表达式及上界。该表达式可以更好地描述不同中继状况的系统性能,具有普遍意义。4.研究了两跳AF协作式传输无线传感器网络的中断概率性能。对于各中继信道具有不同信道状态参数情形,提出了系统中断概率的一种近似表达式。该表达式避免了非线性函数运算,克服了已有近似式在低信噪比情形下误差较大的局限性。仿真结果表明,该表达式更接近于系统的蒙特卡罗仿真结果。5.研究了两跳AF协作式传输无线传感器网络的功率分配问题。基于分布式估计OPA算法的思想,以优化信道容量为目标,提出了一种中继节点选择和功率分配算法,并分别对总功率受限以及总功率与单个节点功率均受限的两种情况进行了分析和仿真,结果表明,在功率受限下,该算法相对于传统的等功率分配算法可以获得较高的遍历容量。6.研究了虚拟MISO(Multiple-Input Single-Output)技术的分簇式无线传感器网络协作传输系统的性能。推导了系统簇内广播阶段、簇间传输阶段和系统整体误符号率(Symbol-Error-Rate, SER)表达式,并提出了系统整体误符号率的一种下界。仿真结果表明,该表达式能很好地描述系统性能。此外,将系统误符号率作为约束,建立了优化系统功率分配模型,并提出了求解该模型极值解的有效方法。仿真结果表明,在一定误符号率要求下,该模型有效地节约了系统能量。更多还原

【Abstract】 The third revolutionary wave in information technology, represented by Internet of Things (IOT), is arriving and deeply affecting the manners of our work and life. Wireless Sensor Network (WSN) technologies guarantee global interconnection and communication capacities of IOT and received extensive concerns in the areas of information terchnology. The WSN is an ad hoc network with limited resources, wireless multi-hop transmission and unreliable nodes, whose performance can be improved by multi-nodes cooperations.This dissertation investigates the multi-nodes cooperation problem of WSN, with an emphasis on the distributed estimation and cooperative transmission technologies. The main contributions of the dissertation are as follows:1. Based on linear minimum mean square error estimation (LMMSE) priniciple, the distributed parameter estimation model was established for the parallel and distributed WSN architecture. An efficient cooperative nodes selection and power allocation algorithm (OPA) was proposed using the mean square error of estimated parameter in LMMSE model as objective function. The proposed algorithm was analyzed both theoretically and numerically for two special cases:1) the WSN has power constraint; 2) the WSN as well as individual nodes have power constraints. Simulation results show that the performance of the proposed algorithm is better than the conventional equal power allocation schemes under the same outrage probality requirements.2. Based on maximum likelihood (ML) estimate priniciple, the distributed parameter estimation model was established for the clustered WSN architecture. An iterative parameter estimation method was proposed through message exchanges between the cluster head node and the ordinary nodes in the cluster. As a result, the information transmission between ordinary nodes and fusion center is avoided and the information processing of fusion center is reduced. The proposed iterative estimation algorithm is proved to converge to the ML estimation results. Besides, the proposed algorithm can be implemented in a parallel and distributed manner. Simulation results show that the proposed algorithm has fast convergence speed in the relatively high signal-to-noise ratio(SNR) regions.3. The cooperative transmission problem in clustered WSN using the amplify-and-forward (AF) technology was studied. The performance of dual-hop AF cooperative transmission system was analyzed. The closed-form probability density function (PDF) of instantaneous received SNR with maxium ratio combining (MRC) criteria was derived under both asymmetric and symmetry channels using the moment generating function (MGF) methods. An exact equation and the corresponding upper bound of the ergodic capacity were also given, which are more suitable to describe the general system.4. The outage probability performance of dual-hop AF cooperative transmission in WSNs was investigated. An approximate outage probability formula was derived with all the relay channels having different state parameters. The formula avoids the nonlinear function operation and overcomes high-SNR limitations of the previous outage probability approximated methods. The simulation results show the formula is more closed to the Monte Carlo performance.5. The power allocation problem of dual-hop AF cooperative transmission in WSNs was investigated. By using the priniciples of the proposed OPA, a relay nodes selection and optimal power allocation strategy was presented using the channel capacity as the objective function. The proposed strategy was analyzed both theoretically and numerically for two special cases:1) the relay nodes have total power constraint; 2) the relay nodes have total power constraint as well as individual relay nodes have power constraints. Simulation results show that the ergodic capacity of the proposed algorithm is higher than the conventional equal power allocation schemes. 6. The cooperative transmission problem in clustered WSN using in virtual MISO technologies was studied. The symbol-error-rate (SER) formulas were derived for the phases of intra-cluster broadcasting, inter-cluster cooperative transmission and end-to-end, respectively. Moreover, a low bound on the end-to-end SER was proposed. Simulation results show that system performance can be well described by the low bound. Besides, an optimal power allocation model using the end-to-end SER as constraints was proposed. An efficient method for solving the optimal solution of the model was proposed. Simulation results show that the model has energy-saving advantages under different SER requirements.更多还原