A Real-Time MAC Protocol for Wireless Sensor Networks: Virtual TDMA for Sensors (VTS)

Wireless Sensor Networks (WSN) are designed for data gathering and processing, with particular requirements and constraints: low hardware complexity, low energy consumption, special traffic pattern support, scalability, and in some cases, real-time operation. In this paper we present the Virtual TDMA for Sensors (VTS) MAC protocol, which intends to support the previous features, focusing particularly on real-time operation. VTS adaptively creates a TDMA arrangement with a number of timeslots equal to the actual number of nodes in range. Thus, VTS achieves an optimal throughput performance compared to TDMA protocols with fixed size of frame. The TDMA frame is set up and maintained by a distributed procedure, which allows sensors to asynchronously join and leave the frame. A major advantage of VTS is that it guarantees a bounded latency, which allows soft real-time applications. An expression for the upper latency bound is also provided in this paper. VTS performance is evaluated by simulation. Results show less power consumption than other proposals in the field. We also introduce a novel multi-hop operation by coordinated sleep/awake cycles among clusters.

[1]  Koen Langendoen,et al.  An adaptive energy-efficient MAC protocol for wireless sensor networks , 2003, SenSys '03.

[2]  Chenxi Zhu,et al.  A Five-Phase Reservation Protocol (FPRP) for Mobile Ad Hoc Networks , 2001, Wirel. Networks.

[3]  Randy H. Katz,et al.  Measuring and Reducing Energy Consumption of Network Interfaces in Hand-Held Devices (Special Issue on Mobile Computing) , 1997 .

[4]  Koen Langendoen,et al.  Energy-Efficient Medium Access Control , 2005, Embedded Systems Handbook.

[5]  Stefano Basagni,et al.  Distributed clustering for ad hoc networks , 1999, Proceedings Fourth International Symposium on Parallel Architectures, Algorithms, and Networks (I-SPAN'99).

[6]  Ian F. Akyildiz,et al.  Wireless sensor and actor networks: research challenges , 2004, Ad Hoc Networks.

[7]  Suresh Singh,et al.  Power efficient MAC protocol for multihop radio networks , 1998, Ninth IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (Cat. No.98TH8361).

[8]  Paul J.M. Havinga,et al.  A Lightweight Medium Access Protocol (LMAC) for Wireless Sensor Networks: Reducing Preamble Transmissions and Transceiver State Switches , 2004 .

[9]  Deborah Estrin,et al.  Medium access control with coordinated adaptive sleeping for wireless sensor networks , 2004, IEEE/ACM Transactions on Networking.

[10]  T. Nieberg,et al.  Advantages of a TDMA based, energy-efficient, self-organizing MAC protocol for WSNs , 2004, 2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514).