Now showing 1 - 3 of 3
  • Publication
    MERLIN : cross-layer integration of MAC and routing for low duty-cycle sensor networks
    Sensor network MAC protocols typically sacrifice packet latency to achieve energy efficiency. Such delays may well increase due to routing protocol operation. For this reason it is imperative that we attempt to quantify the end-to-end delay and energy consumption when jointly using low duty cycle MAC and routing protocols. In this paper, we present a comprehensive evaluation of MERLIN (MAC and efficient routing integrated with support for localization), a cross-layer protocol that integrates both MAC and routing features. In contrast to many sensor network protocols, it employs a multicast upstream and multicast downstream approach to relaying packets to and from the gateway. Simultaneous reception and transmission errors are notified by asynchronous burst ACK and negative burst ACK messages. A division of the network into timezones, together with an appropriate scheduling policy, enables the routing of packets to the closest gateway. An evaluation of MERLIN has been conducted through simulation, against both the SMAC and the ESR routing protocols (an improved version of the DSR algorithm). The results illustrate that the joint usage of both SMAC and ESR, in low duty cycle scenarios, causes extremely high end-to-end delays and prevents acceptable data delivery rate. MERLIN, as an integrated approach, notably reduces latency, resulting in nodes that can deliver data in a very low duty cycle, yielding a significant extension to network lifetime.
      1291Scopus© Citations 42
  • Publication
    Advantages of Dual Channel MAC for Wireless Sensor Networks
    Traditional low cost radios for wireless sensor networks operate with one frequency channel at any given time. However, recent advances in radio hardware for WSNs made available transceivers that can support two simultaneous channels. In this work, we investigate the benefits of using two parallel independent frequency channels at the MAC layer. In particular, the paper introduces a technique of Dual Channel Multiple Access with Adaptive Preamble (DCMA/AP). The protocol uses two separate frequencies for data and control packets to avoid the use of handshake mechanisms (e.g. RTS/CTS) in order to reduce energy consumption and packet delay. To address the hidden and exposed terminal problems, DCMA/AP enables a receiver to send a busy tone signal on the control channel to notify neighbors that an ongoing reception is in progress. As a result, packet collisions are nullified with an increase of node throughput. Furthermore, an adaptive preamble mechanism in DCMA/AP avoids secondary processes of node synchronization together with a reduction of idle listening of receiving nodes that are considered to be one of the major sources of energy consumption in wireless sensor networks. Finally, DCMA/AP introduces a mechanism of opportunistic crossover speeds up the process of packet forwarding by pre-announcing the successive candidate node intended to receive the packet.
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