Poster Abstract: Opportunistic RPL

Sensor nodes constituting Wireless Sensor Networks (WSN) are often battery- operated and have limited resources. To save energy, nodes sleep most of the time, and wake up periodically to handle communication. Such radio duty cycling poses a basic trade-off between energy and latency. In previous work, we have shown that opportunistic routing is an efficient way to achieve low-latency yet energy efficient data collection in WSN (ORW [3]). In this paper, we extend this approach to the context of low-power IP networks, where nodes need to be addressed individually and where traffic patterns are irregular. We present ORPL, an opportunistic extension of RPL, the stan- dard, state-of-the-art routing protocol for low-power IP networks. We discuss our preliminary results obtained with Contiki in a 137-node testbed

Reliable routing scheme for indoor sensor networks

Indoor Wireless sensor networks require a highly dynamic, adaptive routing scheme to deal with the high rate of topology changes due to fading of indoor wireless channels. Besides that, energy consumption rate needs to be consistently distributed among sensor nodes and efficient utilization of battery power is essential. If only the link reliability metric is considered in the routing scheme, it may create long hops routes, and the high quality paths will be frequently used. This leads to shorter lifetime of such paths; thereby the entire network's lifetime will be significantly minimized. This paper briefly presents a reliable load-balanced routing (RLBR) scheme for indoor ad hoc wireless sensor networks, which integrates routing information from different layers. The proposed scheme aims to redistribute the relaying workload and the energy usage among relay sensor nodes to achieve balanced energy dissipation; thereby maximizing the functional network lifetime. RLBR scheme was tested and benchmarked against the TinyOS-2.x implementation of MintRoute on an indoor testbed comprising 20 Mica2 motes and low power listening (LPL) link layer provided by CC1000 radio. RLBR scheme consumes less energy for communications while reducing topology repair latency and achieves better connectivity and communication reliability in terms of end-to-end packets delivery performance

Poster Abstract: MagoNode++ - A Wake-Up-Radio-Enabled Wireless Sensor Mote for Energy-Neutral Applications

The combination of low-power design, energy harvesting and ultra-low-power wake-up radios is paving the way for perpetual operation of Wireless Sensor Networks (WSNs). In this work we present the MagoNode++, a novel WSN platform supporting energy harvesting and radio-triggered wake ups for energy- neutral applications. The MagoNode++ features an energy- harvesting subsystem composed by a light or thermoelectric harvester, a battery manager and a power manager module. It further integrates a state-of-the-art RF Wake-Up Receiver (WUR) that enables low-latency asynchronous communication, virtually eliminating idle listening at the main transceiver. Experimental results show that the MagoNode++ consumes only 2.8uA with the WUR in idle listening and the rest of the platform in sleep state, making it suitable for energy-constrained WSN scenarios and for energy-neutral applications

Power Saving MAC Protocols for WSNs and Optimization of S-MAC Protocol

Low power MAC protocols have received a lot of consideration in the last few years because of their influence on the lifetime of wireless sensor networks. Since, sensors typically operate on batteries, replacement of which is often difficult. A lot of work has been done to minimize the energy expenditure and prolong the sensor lifetime through energy efficient designs, across layers. Meanwhile, the sensor network should be able to maintain a certain throughput in order to fulfill the QoS requirements of the end user, and to ensure the constancy of the network. This paper introduces different types of MAC protocols used for WSNs and proposes S‐MAC, a Medium‐Access Control protocol designed for Wireless Sensor Networks. S‐MAC uses a few innovative techniques to reduce energy consumption and support self‐ configuration. A new protocol is suggested to improve the energy efficiency, latency and throughput of existing MAC protocol for WSNs. A modification of the protocol is then proposed to eliminate the need for some nodes to stay awake longer than the other nodes which improves the energy efficiency, latency and throughput and hence increases the life span of a wireless sensor networ

Hidden Terminal-Aware Contention Resolution with an Optimal Distribution

Achieving low-power operation in wireless sensor networks with high data load or bursty traffic is challenging. The hidden terminal problem is aggravated with increased amounts of data in which traditional backoff-based contention resolution mechanisms fail or induce high latency and energy costs. We analyze and optimize Strawman, a receiver-initiated contention resolution mechanism that copes with hidden terminals. We propose new techniques to boost the performance of Strawman while keeping the resolution overhead small. We finally validate our improved mechanism via experiments

Analysis of Qos Aware Cloud Based Routing for Improved Security

The recent advances and the convergence of micro electro-mechanical systems technology, integrated circuit technologies, microprocessor hardware and Nano-technology, wireless communications, Ad-hoc networking routing protocols, distributed signal processing, and embedded systems have made the concept of Wireless Sensor Networks (WSNs). Sensor network nodes are limited with respect to energy supply, restricted computational capacity and communication bandwidth. Most of the attention, however, has been given to the routing protocols since they might differ depending on the application and network architecture. To prolong the lifetime of the sensor nodes, designing efficient routing protocols is critical. Even though sensor networks are primarily designed for monitoring and reporting events, since they are application dependent, a single routing protocol cannot be efficient for sensor networks across all applications. In this paper, we analyze the design issues of sensor networks and present a classification and comparison of routing protocols. This comparison reveals the important features that need to be taken into consideration while designing and evaluating new routing protocols for sensor networks. A reliable transmission of packet data information, with low latency and high energy-efficiency, is truly essential for wireless sensor networks, employed in delay sensitive industrial control applications. The proper selection of the routing protocol to achieve maximum efficiency is a challenging task, since latency, reliability and energy consumption are inter-related with each other. It is observed that, Quality of Service (QoS) of the network can improve by minimizing delay in packet delivery, and life time of the network, can be extend by using suitable energy efficient routing protocol

Design Aspects of An Energy-Efficient, Lightweight Medium Access Control Protocol for Wireless Sensor Networks

This document gives an overview of the most relevant design aspects of the lightweight medium access control (LMAC) protocol [16] for wireless sensor networks (WSNs). These aspects include selfconfiguring and localized operation of the protocol, time synchronization in multi-hop networks, network setup and strategies to reduce latency.\ud The main goal in designing a MAC protocol for WSNs is to minimize energy waste - due to collisions of messages and idle listening - , while limiting latency and loss of data throughput. It is shown that the LMAC protocol performs well on energy-efficiency and delivery ratio [19] and can\ud ensure a long-lived, self-configuring network of battery-powered wireless sensors.\ud The protocol is based upon scheduled access, in which each node periodically gets a time slot, during which it is allowed to transmit. The protocol does not depend on central managers to assign time slots to nodes.\ud WSNs are assumed to be multi-hop networks, which allows for spatial reuse of time slots, just like frequency reuse in GSM cells. In this document, we present a distributed algorithm that allows nodes to find unoccupied time slots, which can be used without causing collision or interference to other nodes. Each node takes one time slot in control to\ud carry out its data transmissions. Latency is affected by the actual choice of controlled time slot. We present time slot choosing strategies, which ensure a low latency for the most common data traffic in WSNs: reporting of sensor readings to central sinks

The revenge of asynchronous protocols: Wake-up Radio-based Multi-hop Multi-channel MAC protocol for WSN

International audienceSynchronized MAC protocols are now considered as the ultimate solution to access the medium in wireless sensor networks. They guarantee both high throughout and constant latency and achieve reasonable energy consumption performance. However, synchronization is achieved at the cost of a complex framework with low flexibility on its parameters that is not suitable for some network topologies or application requirements. By contrast, asynchronous MAC protocols are versatile by nature but suffer from the tradeoff between energy consumption and latency. However, the addition of Wake-up Radio (WuR) can reduce the energy consumption of such protocols while maintaining very low latency thanks to its always-on feature and ultra-low power consumption. In this article, we present WuR- based Multi-hop Multi-channel (W2M), an asynchronous MAC protocol for wireless sensor networks. We also provide a fair comparison with Time Synchronized Channel Hopping (TSCH) through an extensive simulation campaign based on Contiki-NG and Cooja. Our results show that in low traffic scenarios, W2M outperforms TSCH in reducing both the energy consumption and the latency (at least 68% of energy is saved), but at the cost of slightly lower reliability