In contrast to conventional selleck compound Wireless Local Area Networks (WLANs), where optimizing link throughput is the main focus, node energy consumption is typically a more important performance metric in WSNs. Further, rate-adaptive protocols in WLANs are typically deeply Inhibitors,Modulators,Libraries coupled with 802.11 Request To Send (RTS) and Clear to Send (CTS) message exchanges, but the packets are typically too small in WSNs to justify the RTS/CTS exchanges (e.g., the default MAC payload size is 28 bytes in TinyOS 2.x). Moreover, WLAN MAC typically do not take the cost of acknowledgement packets into account because Inhibitors,Modulators,Libraries the sizes of the data packets are significantly larger than the acknowledgement packets.An Inhibitors,Modulators,Libraries analytical model of the energy consumption under different channel conditions, which we use to optimize the overall network energy consumption.

Evaluation of RA-MAC using both simulation and experiment demonstrates the performance of the protocol. We have demonstrated the feasibility of our RA-MAC protocol using TinyOS [8] running on the off-the-shelf TinyNode platform [9].The rest of the paper is organized as follows. We present related work in Section 2. We discuss our hypothesis regarding adaptive data rates in Section Inhibitors,Modulators,Libraries 3. and set up an analytical model to optimize node energy consumption under different channel conditions in Section 4. We present the details of the proposed RA-MAC protocol in Section 5. Section 6. presents the experimental results that compare the performance of RA-MAC to that of SCP-MAC [10], followed by the simulation comparison between a conventional WLAN rate adaptive algorithm and the proposed RA-MAC in Section 7.

Finally, we present our conclusions in Section 8.2.?Related WorkIn this section, we discuss the related MAC research Batimastat for both wireless sensor networks and conventional wireless local area networks.2.1. Medium Access Control Protocol in WSNsEnergy-efficiency is one of the most important performance metrics in WSNs because sensor nodes typically have a very limited energy supply and are expected to operate independently over a long time-period. This is a significant differentiator between research in WSN MAC and WLAN MAC. Because the traffic load in WSNs is typically low, an effective method to reduce the (idle listening) duty cycles of nodes is of prime importance.S-MAC is a classic CSMA-style protocol for sensor networks [11].

Nodes are coarsely molecular weight calculator time synchronized and transmit using a fixed wake-up schedule in a multi-hop network to save energy. S-MAC enables the nodes to run at duty cycles of 1 �C 10%.T-MAC improves the performance of S-MAC by using an adaptive timer that can adjust the wake-up schedule of a node dynamically based on traffic fluctuations [12].A Low Power Listening (LPL) node periodically and briefly samples the channel for the presence of radio transmissions [13].