Han, ZhuPoor, H. Vincent2020-05-112020-05-1112/18/2007Copyright 2007 IET Microwaves, Antennas and Propagation. This is a pre-print version of a published paper that is available at: https://digital-library.theiet.org/content/journals/10.1049/iet-map_20060294. Recommended citation: Han, Zhu, and Harold Vincent Poor. "Lifetime improvement in wireless sensor networks via collaborative beamforming and cooperative transmission." IET microwaves, antennas & propagation 1, no. 6 (2007): 1103-1110. doi: 10.1049/iet-map:20060294. This item has been deposited in accordance with publisher copyright and licensing terms and with the author's permission.https://hdl.handle.net/10657/6505Collaborative beamforming (CB) and cooperative transmission (CT) have recently emerged as communication techniques that can make effective use of collaborative/cooperative nodes to create a virtual multiple-input/multiple-output system. Extending the lifetime of networks composed of battery-operated nodes is a key issue in the design and operation of wireless sensor networks. The effects on network lifetime of allowing closely located nodes to use CB/CT to reduce the load or even to avoid packet-forwarding requests to nodes that have critical battery life are considered. First, the effectiveness of CB/CT in improving the signal strength at a faraway destination using energy in nearby nodes is studied. Then, the performance improvement obtained by this technique is analysed for a special 2D disc case. Further, for general networks in which information-generation rates are fixed, a new routing problem is formulated as a linear- programming problem, whereas for other general networks, the cost for routing is dynamically adjusted according to the amount of energy remaining and the effectiveness of CB/CT. From the analysis and the simulation results, it is seen that the proposed method can reduce the payloads of energy-depleting nodes by about 90% in the special case network considered and improve the lifetimes of general networks by about 10%, compared with existing techniqueslinear programmingMIMO communicationwireless sensor networksArticle