492 research outputs found

    Proposition and validation of an original MAC layer with simultaneous medium accesses for low latency wireless control/command applications

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    Control/command processes require a transmission system with some characteristics like high reliability, low latency and strong guarantees on messages delivery. Concerning wire networks, field buses technologies like FIP offer this kind of service (periodic tasks, real time constraints...). Unfortunately, few wireless technologies can propose a communication system which respects such constraints. Indeed, wireless transmissions must deal with medium characteristics which make impossible the direct translation of mechanisms used with wire networks. The purpose of this paper is to present an original Medium Access Control (MAC) layer for a real time Low Power-Wireless Personal Area Network (LP-WPAN). The proposed MAC-layer has been validated by several complementary methods; in this paper, we focus on the specific Simultaneous Guaranteed Time Slot (SGTS) part

    On the Medium Access Control Protocols Suitable for Wireless Sensor Networks – A Survey

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    A MAC (Medium Access Control) protocol has direct impact on the energy efficiency and traffic characteristics of any Wireless Sensor Network (WSN). Due to the inherent differences in WSN’s requirements and application scenarios, different kinds of MAC protocols have so far been designed especially targeted to WSNs, though the primary mode of communications is wireless like any other wireless network. This is the subject topic of this survey work to analyze various aspects of the MAC protocols proposed for WSNs. To avoid collision and ensure reliability, before any data transmission between neighboring nodes in MAC layer, sensor nodes may need sampling channel and synchronizing. Based on these needs, we categorize the major MAC protocols into three classes, analyze each protocol’s relative advantages and disadvantages, and finally present a comparative summary which could give a snapshot of the state-of-the-art to guide other researchers find appropriate areas to work on. In spite of various existing survey works, we have tried to cover all necessary aspects with the latest advancements considering the major works in this area

    TRW-MAC: A thermal-aware receiver-driven wake-up radio enabled duty cycle MAC protocol for multi-hop implantable wireless body area networks in Internet of Things

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    Implantable Wireless Body Area Network (IWBAN), a network of implantable medical sensors, is one of the emerging network paradigms due to the rapid proliferation of wireless technologies and growing demand of sophisticated healthcare. The wireless sensors in IWBAN is capable of communicating with each other through radio frequency (RF) link. However, recurring wireless communication inside the human body induces heat causing severe thermal damage to the human tissue which, if not controlled, may appear as a threat to human life. Moreover, higher propagation loss inside the human body as well as low-power requirement of the sensor nodes necessitate multi-hop communication for IWBAN. A IWBAN also requires meeting certain Quality of Service demands in terms of energy, delay, reliability etc. These pressing concerns engender the design of TRW-MAC: A thermal-aware receiver-driven wake-up radio enabled duty cycle MAC protocol for multi-hop IWBANs in Internet of Things. TRW-MAC introduces a thermal-aware duty cycle adjustment mechanism to reduce temperature inside the body and adopts wake-up radio (WuR) scheme for attaining higher energy efficiency. The protocol devises a wake-up estimation scheme to facilitate staggered wake-up schedule for multi-hop transmission. A superframe structure is introduced that utilizes both contention-based and contention free medium access operations. The performance of TRW-MAC is evaluated through simulations that exhibit its superior performance in attaining lower thermal-rise as well as satisfying other QoS metrics in terms of energy-efficiency, delay and reliability

    Novel Medium Access Control (MAC) Protocols for Wireless Sensor and Ad Hoc Networks (WSANs) and Vehicular Ad Hoc Networks (VANETs)

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    Efficient medium access control (MAC) is a key part of any wireless network communication architecture. MAC protocols are needed for nodes to access the shared wireless medium efficiently. Providing high throughput is one of the primary goals of the MAC protocols designed for wireless networks. MAC protocols for Wireless Sensor and Ad hoc networks (WSANs) must also conserve energy as sensor nodes have limited battery power. On the other hand, MAC protocols for Vehicular Ad hoc networks (VANETs) must also adapt to the highly dynamic nature of the network. As communication link failure is very common in VANETs because of the fast movement of vehicles so quick reservation of packet transmission slots by vehicles is important. In this thesis we propose two new distributed MAC algorithms. One is for WSANs and the other one is for VANETs. We demonstrate using simulations that our algorithms outperform the state-of-the-art algorithms

    IEEE 802.15.4e: a Survey

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    Several studies have highlighted that the IEEE 802.15.4 standard presents a number of limitations such as low reliability, unbounded packet delays and no protection against interference/fading, that prevent its adoption in applications with stringent requirements in terms of reliability and latency. Recently, the IEEE has released the 802.15.4e amendment that introduces a number of enhancements/modifications to the MAC layer of the original standard in order to overcome such limitations. In this paper we provide a clear and structured overview of all the new 802.15.4e mechanisms. After a general introduction to the 802.15.4e standard, we describe the details of the main 802.15.4e MAC behavior modes, namely Time Slotted Channel Hopping (TSCH), Deterministic and Synchronous Multi-channel Extension (DSME), and Low Latency Deterministic Network (LLDN). For each of them, we provide a detailed description and highlight the main features and possible application domains. Also, we survey the current literature and summarize open research issues

    Cross-layer signalling and middleware: a survey for inelastic soft real-time applications in MANETs

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    This paper provides a review of the different cross-layer design and protocol tuning approaches that may be used to meet a growing need to support inelastic soft real-time streams in MANETs. These streams are characterised by critical timing and throughput requirements and low packet loss tolerance levels. Many cross-layer approaches exist either for provision of QoS to soft real-time streams in static wireless networks or to improve the performance of real and non-real-time transmissions in MANETs. The common ground and lessons learned from these approaches, with a view to the potential provision of much needed support to real-time applications in MANETs, is therefore discussed

    Chain Routing for Convergecast Small Scale Wireless Sensor Networks

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    Wireless sensor networks have many applications involving autonomous sensors transmitting their data to a sink placed in the network. A protocol by name Chain Routing for Convergecast Small Scale (CRCSS) Wireless sensor networks is proposed in this paper. The set of sensor nodes in the network send the data periodically to the sink located in the area of interest. The nodes who cannot reach sink in one hop choose one of the neighbours for forwarding the data to the sink by forming a chain of links. The selection of forwarding node and the waiting period before forwarding plays an important role in the protocol. The proposed CRCSS protocol exhibits improvement in energy spent per packet and latency per packet for a wireless sensor network as compared to ConverSS protocol for small scale wireless sensor networks. In CRCSS protocol energy spent per packet is independent of the network radius

    Time Segmentation Approach Allowing QoS and Energy Saving for Wireless Sensor Networks

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    Wireless sensor networks are conceived to monitor a certain application or physical phenomena and are supposed to function for several years without any human intervention for maintenance. Thus, the main issue in sensor networks is often to extend the lifetime of the network by reducing energy consumption. On the other hand, some applications have high priority traffic that needs to be transferred within a bounded end-to-end delay while maintaining an energy efficient behavior. We propose MaCARI, a time segmentation protocol that saves energy, improves the overall performance of the network and enables quality of service in terms of guaranteed access to the medium and end-to-end delays. This time segmentation is achieved by synchronizing the activity of nodes using a tree-based beacon propagation and allocating activity periods for each cluster of nodes. The tree-based topology is inspired from the cluster-tree proposed by the ZigBee standard. The efficiency of our protocol is proven analytically, by simulation and through real testbed measurements

    Coordination and Self-Adaptive Communication Primitives for Low-Power Wireless Networks

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    The Internet of Things (IoT) is a recent trend where objects are augmented with computing and communication capabilities, often via low-power wireless radios. The Internet of Things is an enabler for a connected and more sustainable modern society: smart grids are deployed to improve energy production and consumption, wireless monitoring systems allow smart factories to detect faults early and reduce waste, while connected vehicles coordinate on the road to ensure our safety and save fuel. Many recent IoT applications have stringent requirements for their wireless communication substrate: devices must cooperate and coordinate, must perform efficiently under varying and sometimes extreme environments, while strict deadlines must be met. Current distributed coordination algorithms have high overheads and are unfit to meet the requirements of today\u27s wireless applications, while current wireless protocols are often best-effort and lack the guarantees provided by well-studied coordination solutions. Further, many communication primitives available today lack the ability to adapt to dynamic environments, and are often tuned during their design phase to reach a target performance, rather than be continuously updated at runtime to adapt to reality.In this thesis, we study the problem of efficient and low-latency consensus in the context of low-power wireless networks, where communication is unreliable and nodes can fail, and we investigate the design of a self-adaptive wireless stack, where the communication substrate is able to adapt to changes to its environment. We propose three new communication primitives: Wireless Paxos brings fault-tolerant consensus to low-power wireless networking, STARC is a middleware for safe vehicular coordination at intersections, while Dimmer builds on reinforcement learning to provide adaptivity to low-power wireless networks. We evaluate in-depth each primitive on testbed deployments and we provide an open-source implementation to enable their use and improvement by the community
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