study on additional carrier sensing for ieee 802.15.4 wireless sensor networks研究其他载体内部传感为ieee 802.15.4无线传感器网络提供服务.pdf

Sensors 2010, 10, 6275-6289; doi:10.3390/s100706275 OPEN ACCESS sensors ISSN 1424-8220 /journal/sensors Article Study on Additional Carrier Sensing for IEEE 802.15.4 Wireless Sensor Networks Bih-Hwang Lee 1,*, Ruei-Lung Lai 1, Huai-Kuei Wu 2 and Chi-Ming Wong 1 1 Department of Electrical Engineering, National Taiwan University of Science and Technology, 43 Keelung Rd., Section 4, Taipei 106, Taiwan; E-Mails: tony@.tw (R.-L.L.); chiming@.tw (C.-M.W.) 2 Department of Information Networking and System Administration, Ling Tung University, 1 Ling tung Rd., Taichung 408, Taiwan; E-Mail: hkwu@.tw (H.-K.W.) * Author to whom correspondence should be addressed; E-Mail: bhlee@.tw; Tel.: +886-2-2737-6682; Fax: +886-2-2737-6699. Received: 30 March 2010; in revised form: 10 May 2010 / Accepted: 14 May 2010 / Published: 24 June 2010 Abstract: Wireless sensor networks based on the IEEE 802.15.4 standard are able to achieve low-power transmissions in the guise of low-rate and short-distance wireless personal area networks (WPANs). The slotted carrier sense multiple access with collision avoidance (CSMA/CA) is used for contention mechanism. Sensor nodes perform a backoff process as soon as the clear channel assessment (CCA) detects a busy channel. In doing so they may neglect the implicit information of the failed CCA detection and further cause the redundant sensing. The blind backoff process in the slotted CSMA/CA will cause lower channel utilization. This paper proposes an additional carrier sens