Sensor MAC Research Articles

Energy Consumption Analysis of the S-MAC Protocol with Contending Nodes under Unsaturated Conditions

We analyze the energy consumption of the sensor-medium access control (S-MAC) protocol, where contending nodes exist. Because all nodes running the S-MAC within a virtual cluster always behave with a fixed frame length, the behavior should be analyzed based on its frame. Hence, reflecting the frame architecture, we first present an analytic model for the S-MAC behavior with a discrete-time Markov chain, and then we analyze energy consumption under unsaturated conditions.

A Power Control MAC Protocol for Wireless Sensor Networks

Power control scheme is used to reduce energy consumption, but asymmetric transmit powers is the problem which can result in increased collisions and degraded throughput in the scheme. A system model following pareto distribution according to a real network situation is proposed. The performance of the power control scheme in saving energy for wireless sensor networks is studied in this paper. A power control scheme based on SMAC (sensor-MAC) for wireless sensor networks is proposed and evaluated. In the new scheme, the optimum neighbor nodes are selected by a scheduling algorithm which can improve the network topology, reduce the collisions, increase goodput, and confirm the network connectivity. The message is transmitted with the optimum power. Furthermore, the protocol provides a fair share of the medium to low power and high power nodes by the reactive mechanism. The experimental results demonstrate that the new power control MAC (media access control) protocol provides longer lifetime and higher goodput than the current important protocols.

A wireless sensor networks MAC protocol for real-time applications

Wireless sensor networks (WSN) are designed for data gathering and processing, with particular requirements: 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 frame is set up and maintained by a distributed procedure, which allows sensors to asynchronously join and leave the frame. In addition, duty cycle is increased or decreased in order to keep latency constant below a given deadline. Therefore, a major advantage of VTS is that it guarantees a bounded latency, which allows soft real-time applications.

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 wakeup 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.

Addressing Mobility in Wireless Sensor Media Access Protocol

Handling mobility in wireless sensor networks presents several new challenges. Techniques developed for other mobile networks, such as mobile phone or mobile adhoc networks can not be applicable, as in these networks energy is not a very critical resource. This paper presents a new adaptive Mobility-aware Sensor MAC protocol (MS-MAC) for mobile sensor applications. In MS-MAC protocol, a node detects its neighbor's mobility based on a change in its received signal level from the neighbor, or a loss of connection with this neighbor after a timeout period. By propagating mobility presence information, and distance from the nearest border node, each node learns its relative distance from the nearest mobile node and from the nearest border node. Depending on the mobile node movement direction, the distances from mobile and border nodes, a node may trigger its neighbor search mechanism to quicken the connection setup time. The simulation results show that, the new mobility-aware MAC protocol can work very energy-efficiently when the network is stationary, whereas it performs much better in terms of throughput than the existing sensor MAC (SMAC) protocol in scenarios involving mobile sensors.

MH-TRACE: Multihop Time Reservation Using Adaptive Control for Energy Efficiency

In this paper, we propose multihop time reservation using adaptive control for energy efficiency (MH-TRACE), which is a medium access control (MAC) protocol that combines advantageous features of fully centralized and fully distributed networks for energy-efficient real-time packet broadcasting in a multihop radio network. We introduce a novel clustering algorithm that dynamically organizes the network into two-hop clusters. MH-TRACE clusters are just for coordinating channel access and minimizing interference; thus, ordinary nodes are not static members of any cluster. Time is organized into cyclic superframes, which consist of several time frames, to support reservation-based periodic channel access for real-time traffic. Each clusterhead chooses the frame with least interference based on its own measurements for the operation of its cluster. Energy dissipation for receiving unwanted or collided data packets or for waiting in idle mode is avoided through the use of information summarization packets sent prior to the data transmissions by the source nodes. Through the use of transmission schedules within each cluster, managed by the clusterheads, intracluster data collisions are completely eliminated and intercluster collisions are minimized. We investigated MH-TRACE through extensive simulations and theoretical analysis. Our results show that MH-TRACE outperforms existing distributed MAC protocols like IEEE 802.11 and sensor MAC, in terms of energy efficiency and throughput, approaching the theoretical maximum throughput and theoretical minimum energy dissipation.