| Wireless sensor networks is formed by a large number of self-organized sensor node, which can monitoring, sensing and gathering information on a variety of objects. Sensors usually operate on battery which is difficult to recharge or replace due to environmental reasons.Thus, a typical characteristic of sensor networks is energy constrained, improving energy efficiency is an important goal in network research.Recently proposed cooperative MIMO is an effective energy-saving technology for sensor networks, which use the feature that sensor nodes are densely distributed, a number of single-antenna sensor nodes to form virtual multi-antenna array in a cooperative way to achieve reliable transmission at low energy consumption. The energy efficiency optimization of cooperative MIMO concerns with two aspects:One is to enable the lowest data transmission energy consumption; the other is to balance energy consumption of all nodes in networks for prolong survival time.This paper analysis the local transmission and long-haul transmission energy consumption in cooperative MIMO in detailed. A minimum data transmission energy consumption model of cooperative MIMO is established. Configure communication parameters (the number of cooperative nodes, etc.) according to the distance between data source node and sink node dynamically, the total energy consumption can meet minimum.To balance energy consumption of nodes in networks, this paper discusses the cooperative node selection method. Two selection methods were proposed. One chooses the maximum remain energy node to be cooperative node which is for a denser sensor networks. The other takes the location of nodes to considering reduce the local transmission energy cost, which is for the more sparse networks.Simulation results give the typical cooperative MIMO communications parameters settings, and the performance of node selection methods is compared in different application environments. The research conclusion is given at the end. |
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