Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Energy Efficiency Optimization of Cooperative Communication in Wireless Sensor Networks Shaoqing Wang and Jingnan Nie | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2010 Article ID 162326 8 pages doi 2010 162326 Research Article Energy Efficiency Optimization of Cooperative Communication in Wireless Sensor Networks Shaoqing Wang and Jingnan Nie Department of Wireless Communication Institute of Communications Engineering PLA University of Science and Technology Nanjing Jiangsu 210007 China Correspondence should be addressed to Shaoqing Wang wangwangsq666@ Received 29 October 2009 Revised 8 March 2010 Accepted 25 April 2010 Academic Editor Xinbing Wang Copyright 2010 S. Wang and J. Nie. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. In wireless sensor networks WSNs cooperative communication represents a potential candidate to combat the effects of channel fading by exploiting diversity gain achieved via cooperation among the relays nodes. However for the energy-constrained WSN to what extent cooperative communication can save energy consumption for a successful packet transmission is still unknown. Energy efficiency of cooperation and direct transmission schemes in WSN is studied and compared in this paper. The expressions of energy efficiency of the two schemes are derived respectively. The numerical results reveal that for the small distance separation between the source and destination nodes the direct transmission scheme is more energy efficient than cooperation and the relay location packet size and modulation level have important effects on energy efficiency. At last energy efficiency maximization for the cooperative communication system is achieved by optimizing both the packet size and modulation level jointly. 1. Introduction Wireless sensor networks WSNs are composed of nodes typically powered by batteries for which replacement or recharging is .
