Jean-Dominique Decotignie

WiseMAC: an ultra low power MAC protocol for the downlink of infrastructure wireless sensor networks

This work proposes wiseMAC(wireless sensor MAC) for the downlink of infrastructure wireless sensor networks. WiseMAC is a novel energy efficient medium access control protocol based on synchronized preamble sampling. The trade-off between power consumption and delay is analyzed, focusing on low traffic. WiseMAC is compared analytically with the power management protocol used in the IEEE 802.15.4 ZigBee standard. It is shown that WiseMAC can provide a significantly lower power consumption for the same delay.

WiseNET: an ultralow-power wireless sensor network solution

A wireless sensor network consists of many energy-autonomous microsensors distributed throughout an area of interest. Each node monitors its local environment, locally processing and storing the collected data so that other nodes can use it. To optimize power consumption, the Swiss Center for Electronics and Microtechnology has developed WiseNET, an ultralow-power platform for the implementation of wireless sensor networks that achieves low-power operation through a careful codesign approach. The WiseNET platform uses a codesign approach that combines a dedicated duty-cycled radio with WiseMAC, a low-power media access control protocol, and a complex system-on-chip sensor node to exploit the intimate relationship between MAC-layer performance and radio transceiver parameters. The WiseNET solution consumes about 100 times less power than comparable solutions.

Ethernet-Based Real-Time and Industrial Communications

Despite early attempts to use Ethernet in the industrial context, only recently has it attracted a lot of attention as a support for industrial communication. A number of vendors are offering industrial communication products based on Ethernet and TCP/IP as a means to interconnect field devices to the first level of automation. Others restrict their offer to communication between automation devices such as programmable logic controllers and provide integration means to existing fieldbuses. This paper first details the requirements that an industrial network has to fulfill. It then shows how Ethernet has been enhanced to comply with the real-time requirements in particular in the industrial context. Finally, we show how the requirements that cannot be fulfilled at layer 2 of the OSI model can be addressed in the higher layers adding functionality to existing standard protocols.

Low power downlink MAC protocols for infrastructure wireless sensor networks

This paper addresses low power medium access control (MAC) protocols for the downlink channel of infrastructure wireless sensor networks. Access points are assumed to be energy unconstrained. The trade-off between the power consumption of the sensor nodes and the transmission delay is analyzed, focusing on low traffic. We describe WiseMAC (Wireless Sensor MAC), a new protocol for the downlink of infrastructure wireless sensor networks. Another original contribution is the presentation and analysis of PTIP (Periodic Terminal Initiated Polling). Here, polling is used in the reversed direction as compared to common polling protocols. WiseMAC and PTIP are compared with PSM (Power Save Mode), the power save protocol used in both the IEEE 802.11 and IEEE 802.15.4 ZigBee standards. Analytical expressions are derived for the power consumption and the transmission delay for each protocol, as a function of the wake-up period. It is shown that WiseMAC provides, with low bit rate radio transceivers, a significantly lower power consumption than PSM. Although less energy efficient than WiseMAC and PSM, it is shown that PTIP can, thanks to its implementation simplicity, become attractive for applications tolerating large transmission delays.

Poster abstract: wiseMAC, an ultra low power MAC protocol for the wiseNET wireless sensor network

WiseMAC is a medium access control protocol designed for the WiseNET™ wireless sensor network. It is based on CSMA and uses the preamble sampling technique to minimize the power consumed when listening to an idle medium. A unique feature of this protocol is to exploit the knowledge of the sampling schedule of its direct neighbors in order to use a wake-up preamble of minimized size. This scheme allows not only to reduce the transmit and the receive power consumption, but also brings a drastic reduction of the energy wasted due to overhearing. Backoff and medium reservation schemes have been selected to provide fairness and collision avoidance. WiseMAC requires no set-up signaling, no network-wide time synchronization and is adaptive to the traffic load. It provides an ultra-low average power consumption in low traffic conditions and a high energy efficiency in high traffic conditions.

WIRELESS FIELDBUSSES – A SURVEY OF ISSUES AND SOLUTIONS

Abstract Connecting sensors and actuators by wireless links is the next step in fieldbus technology. We present here the problems that need to be solved and some proposals in the industrial domain. It appears that there is no straightforward solution to the problem. Possible wireless LAN solutions are described and checked for suitability.

Soft deadline bounds for two-way transactions in Buetooth piconets under co-channel interference

This paper presents the delay performances of two-way transactions implemented on top of the Bluetooth HCI layer. The two-way transaction, formally called the Send Data with Acknowledge (SDA) service primitive, is a fundamental building block for real-time protocols. We analyze its delay performances under packet loss probability caused by a number of co-located interfering piconets. We first present a probabilistic treatment of the performance of a Bluetooth piconet under co-channel interference from other Bluetooth piconets. An upper bound on the packet error rate is analytically derived. Simulation results validating the theoretical results are shown. The obtained packet error rate bounds are then applied to the problem of deadline for two-way transactions. The probability that a deadline will be met is introduced, as well as the value of the deadline in function of the desired probability that the deadline will be met.

Producer-Distributor-Consumer Model on Controller Area Network

Abstract A fundamental requirement of distributed control systems is to ensure real-time traffic. This traffic can be split into two groups: sporadic and periodic. Among RTLAN proposals, CAN is well adapted to sporadic message transfers whereas FIP has been optimized for periodic traffic that is handle in a deterministic way. The goal of this paper is to adapt the Producer-Distributor-Consumer model (FIP) to CAN in order to ensure the timing requirements of periodic traffic. We propose an application layer that uses CAN services based on the PDC model. Two architectures of distributor are presented: decentralized and centralized. We show how this model may coexist with the client server model as defined in the CAN application layer.

Requirements for wireless extensions of a FIP fieldbus

We study wireless communications within the context of industrial applications. The question of interest is whether or not wireless connections can be used for accessing distant sensors and actuators through fieldbus. Another question of interest is whether the bandwidth of currently available wireless connections allow the access to distant sensors/actuators through a fieldbus protocol. The paper describes a repeater design for the extension of a FIP standard fieldbus.

Accurate Timeliness Simulations for Real-Time Wireless Sensor Networks

The use of wireless sensor networks is rapidly growing in various types of applications that benefit from spatially distributed data collection. Some of these applications, such as industrial automation, fire detection or health monitoring, have strong timeliness constraints. Since field deployments are difficult to monitor and debug, the development of real-time communication protocols for wireless sensor networks necessitates accurate simulation models. This paper presents open source Omnet++ simulation models based on the IEEE 802.15.4 standard. Four evaluation scenarios are used to compare simulation timeliness and packet error rate results with experimental measurements. The small scale of the scenarios allows to isolate the effect of each system component. The comparison validates the models for timeliness estimates in sensor networks and pinpoints the variability of software implementations in embedded systems as a major cause of differences between simulated and measured results.