Now showing 1 - 3 of 3
  • Publication
    Portability versus effciency tradeoffs in MAC implementations for microsensor platforms
    Abstract—Medium Access Control (MAC) implementations control access of network devices to a transmission medium. For emerging communication protocols, the MAC is typically implemented in software, to enable adaptation to evolving defacto or industry standards. Software MAC implementations are typically realized as state machines, executing code related to successive MAC states within periodic interrupts. This software construct yields minimal memory footprint and energy efficiency, but the resulting implementations are often tightly coupled to the platform’s system software, and are thus non-portable across hardware and system platforms. This article presents an architecture that decouples MAC and system software, enabling portability, while preserving software efficiency.
      1031Scopus© Citations 1
  • Publication
    Coordinated sleeping for beaconless 802.15.4-based multihop networks
    The last few years have seen a wide adoption of the IEEE 802.15.4 MAC/PHY standard for low-power communication between wireless sensor nodes. Within this work we study some fundamental drawbacks of the 802.15.4 specifications for multihop network deployments, which adversely affect the delivery rate and efficient node energy consumption. These issues are rectified by investigating a timezone-based scheduling, V-Route, that builds on 802.15.4 beaconless mode to enable both a synchronized sleep scheduling and a bidirectional communication between nodes in the sensor network and the PAN coordinator. The contributions of V-Route are threefold: (1) mitigate collisions, (2) enable packet routing and (3) provide energy saving in a multihop context, while maintaining the full compliancy with the 802.15.4 standard. We present a performance evaluation on energy consumption and latency with real experiments on Philips AquisGrain sensor nodes. Enhancing 802.15.4-based multi-hop networks with V-Route yields energy reduction ranging from 27.3% to 85.3%, according to the required end-to-end latency.
      2058Scopus© Citations 2
  • Publication
    A framework for time-controlled and portable WSN applications
    Body sensor network applications require a large amount of data to be communicated over radio frequency. The radio transceiver is typically the largest source of power dissipation; improvements on energy consumption can thus be achieved by enabling on-node processing to reduce the number of packets to be transmitted. On-node processing is facilitated by a timely control over process execution to sequence operations on data; yet, the latter must be enabled while keeping highlevel software abstracted from both underlying software and hardware intricacies to accommodate portability to the wide range of hardware and software platforms. We investigated the challenges of implementing software services for on-node processing and devised constructs and system abstractions that integrate applications, drivers, time synchronization and MAC functionality into a system software which presents limited dependency between components and enables timely control of processes. We support our claims with a performance evaluation of the software tools implemented within the FreeRTOS micro-kernel.
      1738Scopus© Citations 1