The Key Technology Of Cooperative Wireless Sensor Networks For Drilling Engineering Monitoring

Wireless sensor networks are the important subject for the modern management and safe production of drilling operation. However, the sensor node is powered by the energy-limited battery, hence improving energy efficiency is extremely significant for lengthening network lifetime. The cooperative multiple input multiple output scheme is able to get multiplexing gain and diversity gain, hence CMIMO as an energy efficient technology has been the attention of many researchers. The drilling engineering monitoring is a typical event-driven and time-driven hybrid wireless sensor network system. On the one hand, there is a need to monitor the characteristics of some emergency and transmit information to the monitoring center accurately, in order to judge the unpredictable accidents timely. On the other hand, there is a need to periodically collect information, in order to establish the database of drilling process. Two energy efficient CMIMO transmission strategies are proposed for the specific application environment to prolong lifetime. This work contain two main aspects:1) Considering the randomness of events in space and time, aiming at the large-scale event-driven drilling engineering monitoring, an energy-efficient CMIMO multi-hop transmission strategy based on STBC is proposed. The strategy establishes the comprehensive multiple-hop relay routing rule considering the residual energy available of nodes, optimal hop distance and other factors. The detailed energy consumption model is established to solve the optimal number of cooperative nodes and hop distance ensuring minimal energy expenditure. Experimental results show the optimal hop distance and number of cooperative nodes solved by the optimization model can reduce energy expenditure dramatically, the proposed transmission strategy can lengthen network lifetime obviously compared with the existing ARPEES protocol.2) Considering the well site periodic characteristics of information acquisition, and that existing CMIMO-based transmission schemes generally fail to take full advantage of the heterogeneity between sensor nodes, we propose an energy-efficient V-BLAST-based cluster-head cooperative MIMO transmission strategy for time-driven drilling engineering monitoring heterogeneous wireless sensor network. In order to maximize the network stable time, we develop energy model to find directly the optimal network parameters ensuring minimal energy expenditure. Experimental results show the optimal network parameters reduce energy expenditure obviously, the strategy can prolong the stable time greatly in comparison with the existing SEP and VCHCT transmission scheme.