Anis Koubâa, Mario Alves, Eduardo Tovar
PP-HURRAY! Research Group, Polytechnic Institute of Porto Rua Dr. Antonio Bernardino de Almeida, 431, 4200-072 Porto, PORTUGAL {akoubaa, emt}@dei.isep.ipp.pt, mjf@isep.ipp.pt
Abstract. Wireless Sensor Networks (WSNs) have been attracting increasing interest for supporting a new generation of ubiquitous computing systems with great potential for many applications such as surveillance, environmental monitoring, health care monitoring or home automation. However, the communication paradigms in WSNs differ from the ones associated to traditional wireless networks, triggering the need for new communication protocols. In this context, the IEEE 802.15.4 protocol presents some potentially interesting features for supporting large-scale ubiquitous computing applications, namely power-efficiency, timeliness and scalability. Nevertheless, when addressing applications with (soft/hard) timing requirements some inherent paradoxes emerge, such as power-efficiency versus timeliness. Consequently, there is the need of engineering solutions for an efficient deployment of IEEE 802.15.4 in such scenarios. In this paper, we present some of the most important results on the IEEE 802.15.4 protocol that have been achieved within the context of wireless sensor networks. The paper outlines the most relevant characteristics of the IEEE 802.15.4 protocol and presents the most important research challenges regarding time-sensitive WSN-based applications. Then, it presents some timing performance analysis that unveils some directions for resolving the previously mentioned paradoxes.
1. Introduction
Wireless Sensor Networks (WSNs) have revolutionized the design of emerging embedded systems and triggered a new set of potential applications. This particular form of distributed and ubiquitous computing raises many challenges in terms of real-time
References: Akyildiz IF, Su W, Sankarasubramaniam Y, and Cayirci E (2002) Wireless sensor networks: A survey. Journal of Computer Networks, vol. 38, pp.393-422. Bacco GD, Melodia T, and Cuomo F (2004) A MAC protocol for delay-bounded applications in wireless sensor networks. In Proc. of the Third Annual Mediterranean Ad Hoc Networking Workshop (MedHoc '04), June 27-30. Bandyopadhyay S, and Coyle EJ (2003) An energy efficient hierarchical clustering algorithm for wireless sensor networks. In Proc. of the Twenty-Second Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM 2003), vol. 3, 30 March - 3 April. Crossbow Tech. (2005) Avoiding RF interference between WiFi and Zigbee, Crossbow Technical Report. Ha J, Kwon WH, Kim JJ, Kim YH, and Shin YH (2005) Feasibility analysis and implementation of the IEEE 802.15.4 multi-hop beacon-enabled network. In Proc. of the 15th Joint Conference on Communications & Info, Jun. 2005. He T, Stankovic JA, Lu C, Abdelzaher T (2003) SPEED: A stateless protocol for real-time communication in sensor networkss. In Proc. of the 23rd IEEE International Conference on Distributed Computing Systems (ICDCS '03): 46-55. Howitt I, and Gutierrez JA (2003) IEEE 802.15.4 low rate-wireless personal area network coexistence issues. IEEE Wireless Communications and Networking Conference (WCNC '03), vol. 3, pp. 1481- 1486, 16-20 Mar. 2003. Hwang L, Sheu ST, Shih YY, and Cheng YC (2005) Grouping strategy for solving hidden terminal problem in IEEE 802.15.4 LR-WPAN. In Proc. of the 1st International Conference on Wireless Internet (WICON '05), pp. 26-32. IEEE 802.11 Specification (1999) IEEE Standards for Information Technology, Telecommunications and Information Exchange between Systems - Local and Metropolitan Area Network - Specific Requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. IEEE 802.15.4 Standard (2003) Part 15.4: Wireless medium access control (MAC) and physical layer (PHY) specifications for Low-Rate Wireless Personal Area Networks (LR-WPANs), IEEE Standard for Information Technology, IEEE-SA Standards Board, 2003. Koubâa A, Alves M, and Tovar E (2006a) Energy/Delay trade-off of the GTS allocation mechanism in IEEE 802.15.4 for wireless sensor networks. IPP-HURRAY Technical Report, HURRAY-TR-060103, (Submitted), Jan. 2006. Koubâa A, Alves M, Tovar E, and Song YQ (2006b) On the performance limits of slotted CSMA/CA in IEEE 802.15.4 for broadcast transmissions in wireless sensor networks. Hurray Technical Report, (submitted). Lu C, Blum BM, Abdelzaher T, Stankovic J, and He T (2002) RAP: A real-time communication architecture for large-scale wireless sensor networks. In IEEE Real-Time and Embedded Technology and Applications (RTAS 2002), Sept. 2002. MICAz datasheet (2004), http://www.xbow.com Mišic J, and Mišic B (2005a) Access delay and throughput for uplink transmissions in IEEE 802.15.4 PAN. Elsevier Computer Communications Journal, vol. 28, N.10, pp.1152-1166, Jun. 2005. Mišic J, Shafi S, and Mišic B (2005b) The impact of MAC parameters on the performance of 802.15.4 PAN. Elsevier Ad hoc Networks Journal, vol. 3, N. 5, pp.509–528, 2005. Park TR, Kim T, Choi J, Choi S, and Kwon W (2005) Throughput and energy consumption analysis of IEEE 802.15.4 slotted CSMA/CA", IEEE Electronics Letters, vol. 41, issue 18, pp. 1017-1019, Sept. 2005. Pollin S, et al. (2005) Performance analysis of slotted IEEE 802.15.4 medium access layer. Technical Report, DAWN Project, Sep. 2005. http://www.soe.ucsc.edu/research/ccrg/DAWN/papers/ZigBee_MACvPV.pdf Shin SY, Choi S, Park HS, and Kwon WH (2005) Packet error-rate analysis of IEEE 802.15.4 under IEEE 802.11b interference. In Proc. of Conference on Wired/Wireless Internet Communications (WWIC '2005), Springer LNCS, vol. 3510, Xanthi (Greece), 11-13 May, 2005. Stankovic J, Abdelzaher T, Lu C, Sha L, and Hou J (2003) Real-Time communication and coordination in embedded sensor networks. Proceedings of IEEE, vol. 91, N. 7, pp.1002-1022. Ye W, Heidemann J, and Estrin D, (2004) Medium access control with coordinated adaptive sleeping for wireless sensor networks. IEEE/ACM Trans. on Networking, vol. 12 , Iss. 3, pp. 493 - 506 Apr. 2004. ZigBee Alliance (2005), ZigBee specification – June 2004, http://www.caba.org/standard/zigbee.html