Research On Cluster-based Virtual MIMO Transmission Scheme For Wireless Sensor Networks

Wireless sensor networks (WSN) is considered as a revolutionary technology leading the development of future economic and society. Through the integration of cyber and physical worlds, WSN enables people to sense, communicate and interact with the physical world in all aspects of daily life, military, aerospace, energy, biology, etc, and thus has gained more and more attention from academy and industry. However, WSN has constrained energy constraint, which is different from traditional wireless self-organization network. Therefore, how to prolong the network lifetime by decreasing energy consumption is one of the most key problems in the research field of WSN.Wireless transceivers usually consume a major portion of batter energy in WSN, and MIMO (Multi-input Multi-output) technique is shown to be a perfect solution to enhance wireless communication energy efficiency. Through using multiple-antennas in transmitting and receiving end, the MIMO technique could achieve diversity gain, which could significantly reduce energy consumption under the same transmit power budget and bit error rate. However, due to the constraints of size, power and cost, it is impossible to equip each sensor with multiple antennas to realize MIMO communications for WSN. In order to tackle this problem, researchers propose the virtual MIMO technique to allow multiple single-antenna nodes cooperate with each other, forming a virtual multi-antennas node. Using virtual MIMO technique in WSN could make use of the diversity gain to decrease the transmission energy consumption. Therefore, the virtual MIMO technique is regarded as a promising solution to prolong the lifetime of WSN. However, the application of virtual MIMO technique to WSN still faces many problems, in which how to design an energy efficient virtual MIMO transmission scheme is one of the key problems.Taking network-lifetime maximization as our primary purpose, we investigate the problem on how to design an energy efficient virtual MIMO transmission scheme, and propose two novel cluster-based virtual MIMO transmission schemes. The major contents and contributions of this paper are as follows:1) Cluster-based virtual MIMO transmission scheme is shown to significantly enhance transmission energy efficiency. However, existing works only consider how to reduce the energy consumption of inter-cluster transmission by cooperative communication, and intra-cluster transmission still use traditional SISO (Single-input Single-output) communication, which consume more energy. In this paper, we propose a new cluster-based virtual MIMO transmission scheme (ICPVM) by combining cooperative data aggregation with cluster protocol. Through selecting intra-cluster cooperative pairs (CPN) for data aggregation, the proposed scheme can obtain energy savings of intra-cluster transmission. We formalize the CPN selection problem to the maximum weighted matching (MWM) in general graphs, and adopt PGA (Path Grow Algorithm) to solve it. Simulation results show that compared with the previous virtual MIMO transmission scheme, our scheme prolongs the network lifetime by at least 27%.2) Multi-hop communication is an important feature of WSN, and data transmission energy consumption could be reduced further by incorporating multihop routing and virtual MIMO technique. So far, the existing virtual MIMO multi-hop transmission schemes'single-hop consists of least two steps: intra-cluster data broadcast and inter-cluster cooperative forwarding. In this paper, we propose a virtual MIMO multicast based multihop transmission scheme (VMMM). Through avoiding intra-cluster broadcast in multi-hop data forwarding process, this transmission scheme can greatly improve the energy efficiency of WSN. In order to optimize the performance of VMMM, we first analyze the energy consumption of this scheme, and then develop a jointly optimization model to determine the optimum network parameters. Simulation results show that compared with the previous virtual MIMO multi-hop transmission scheme, our scheme prolongs the network lifetime by at least 50%.