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: Optimal Throughput and Energy Efficiency for Wireless Sensor Networks: Multiple Access and Multipacket | EURASIP Journal on Wireless Communications and Networking 2005 4 541-553 2005 Optimal Throughput and Energy Efficiency for Wireless Sensor Networks Multiple Access and Multipacket Reception Wenjun Li Department of Electrical and Computer Engineering North Carolina State University Raleigh NC 27695-7914 USA Email wli5@ Huaiyu Dai Department of Electrical and Computer Engineering North Carolina State University Raleigh NC 27695-7914 USA Email huaiyu-dai@ Received 9 December 2004 Revised 1 April 2005 We investigate two important aspects in sensor network design the throughput and the energy efficiency. We consider the uplink reachback problem where the receiver is equipped with multiple antennas and linear multiuser detectors. We first assume Rayleigh flat-fading and analyze two MAC schemes round-robin and slotted-ALOHA. We optimize the average number of transmissions per slot and the transmission power for two purposes maximizing the throughput or minimizing the effective energy defined as the average energy consumption per successfully received packet subject to a throughput constraint. For each MAC scheme with a given linear detector we derive the maximum asymptotic throughput as the signal-to-noise ratio goes to infinity. It is shown that the minimum effective energy grows rapidly as the throughput constraint approaches the maximum asymptotic throughput. By comparing the optimal performance of different MAC schemes equipped with different detectors we draw important tradeoffs involved in the sensor network design. Finally we show that multiuser scheduling greatly enhances system performance in a shadow fading environment. Keywords and phrases throughput energy efficiency multiuser diversity scheduling slotted-ALOHA linear multiuser detector. 1. INTRODUCTION Wireless sensor networks have become one of the burgeoning research fields in recent years as they are envisioned to have wide applications in military environmental and many other
