A power controlled interference aware routing protocol for dense multi-hop wireless networks

A key issue impacting the performance of multi-hop wireless networks is the interference among neighboring nodes. In this paper, we propose a novel and practical interference aware metric, termed as Network Allocation Vector Count (NAVC), to estimate the effects of the interference on the average delay and the available bandwidth. This metric can be easily applied to routing protocols designed for 802.11 based multi-hop networks with no modification to the current 802.11 protocol. The design of NAVC as a metric for the AODV [32] routing protocol, as well as a metric for transmit power control, are described in detail. Our simulation results reveal that the NAVC-driven AODV can greatly improve its performance compared to those protocols based on hop-count. For scenarios of densely deployed nodes, the throughput improvement is often a factor near two, indicating that NAVC is more useful as networks grow denser. Moreover, the network lifetime can be notably prolonged when the NAVC is employed to conduct transmit power control. Our approach is essential for emerging applications such as wireless sensor networks where the interference is heavy and the energy is severely constrained.     

无线传感器网络拓扑控制策略研究

节能设计是无线传感器网络的首要设计目标,拓扑控制是实现该目标的重要技术之一,其主要目标是在保证网络连通和覆盖的前提下剔除不必要的通信链路,降低节点能耗和减少通信干扰,为MAC协议和路由协议的顺利执行提供基础。文中对传感器网络拓扑控制策略进行了的分析。最后针对目前传感器节点成本仍然很高这一特点,通过仿真得出了在节点随机配置的情况下,保证网络连通和覆盖所需的至少节点数目。并通过仿真分析证明了方案的可行性。     

A new QoS routing algorithm based on self-organizing maps for wireless sensor networks

For the past ten years, many authors have focused their investigations in wireless sensor networks. Different researching issues have been extensively developed: power consumption, MAC protocols, self-organizing network algorithms, data-aggregation schemes, routing protocols, QoS management, etc. Due to the constraints on data processing and power consumption, the use of artificial intelligence has been historically discarded. However, in some special scenarios the features of neural networks are appropriate to develop complex tasks such as path discovery. In this paper, we explore and compare the performance of two very well known routing paradigms, directed diffusion and Energy-Aware Routing, with our routing algorithm, named SIR, which has the novelty of being based on the introduction of neural networks in every sensor node. Extensive simulations over our wireless sensor network simulator, OLIMPO, have been carried out to study the efficiency of the introduction of neural networks. A comparison of the results obtained with every routing protocol is analyzed. This paper attempts to encourage the use of artificial intelligence techniques in wireless sensor nodes.     

Opportunistic routing with in-network aggregation for asynchronous duty-cycled wireless sensor networks

We propose an opportunistic routing protocol for wireless sensor networks designed to work on top of an asynchronous duty-cycled MAC. Opportunistic routing can be very effective when used with asynchronous duty-cycled MAC because expected waiting time of senders—when they stay on active mode and transmit packet streams—is significantly reduced. If there are multiple sources, energy consumption can be reduced further through in-network aggregation. The idea proposed in this paper is to temporarily increase duty cycle ratio of nodes holding packets, in order to increase chance of in-network aggregation and thus reduce energy consumption and extend network lifetime. In the proposed protocol called opportunistic routing with in-network aggregation (ORIA), whenever a node generates a packet or receives a packet to forward, it waits for a certain amount of time before transmitting the packet. Meanwhile, the node increases its duty cycle ratio, hoping that it receives packets from other nodes and aggregate them into a single packet. Simulation results show that ORIA saves considerable amount of energy compared to general opportunistic routing protocols, as well as tree-based protocols.     

Routing in mobile wireless sensor network: a survey

The Mobile Wireless Sensor Network (MWSN) is an emerging technology with significant applications. The MWSN allows the sensor nodes to move freely and they are able to communicate with each other without the need for a fixed infrastructure. These networks are capable of out-performing static wireless sensor networks as they tend to increase the network lifetime, reduce the power consumption, provide more channel capacity and perform better targeting. Usually routing process in a mobile network is very complex and it becomes even more complicated in MWSN as the sensor nodes are low power, cost effective mobile devices with minimum resources. Recent research works have led to the design of many efficient routing protocols for MWSN but still there are many unresolved problems like retaining the network connectivity, reducing the energy cost, maintaining adequate sensing coverage etc. This paper addresses the various issues in routing and presents the state of the art routing protocols in MWSN. The routing protocols are categorized based on their network structure, state of information, energy efficiency and mobility. The classification presented here summarizes the main features of many published proposals in the literature for efficient routing in MWSN and also gives an insight into the enhancements that can be done to improve the existing routing protocols.     

Non-intrusive aggregation in wireless sensor networks

Since energy is scarce in sensor nodes, wireless sensor networks aim to transmit as few packets as possible. To achieve this goal, sensor protocols often aggregate measured data from multiple sensor nodes into a single packet. In this paper, a survey of aggregation techniques and methods is given. Based on this survey, it is concluded that there are currently several dependencies between the aggregation method and the behavior of the other network layers. As a result, existing aggregation methods can often not be combined with different routing protocols. To remedy this shortcoming, the paper introduces a new ‘non-intrusive’ aggregation approach which is independent of the routing protocol. The proposed aggregation method is evaluated and compared to traditional aggregation approaches using a large-scale sensor testbed of 200 TMoteSky sensor nodes. Our experimental results indicate that existing aggregation approaches are only suited for a limited set of network scenarios. In addition, it is shown both mathematically and experimentally that our approach outperforms existing non-intrusive techniques in a wide range of scenarios.     

Variable-Range Transmission Power Control in Wireless Ad Hoc Networks

In this paper, we investigate the impact of variable-range transmission power control on the physical and network connectivity, on network capacity, and on power savings in wireless multihop networks. First, using previous work by Steele (1988), we show that, for a path attenuation factor a = 2, the average range of links in a planar random network of A m² having n nodes is ~aradicA/n1. We show that this average range is approximately half the range obtained when common-range transmission control is used. Combining this result and previous work by Gupta and Kumar (2000), we derive an expression for the average traffic carrying capacity of variable-range-based multihop networks. For a = 2, we show that this capacity remains constant even when more nodes are added to the network. Second, we derive a model that approximates the signaling overhead of a routing protocol as a function of the transmission range and node mobility for both route discovery and route maintenance. We show that there is an optimum setting for the transmission range, not necessarily the minimum, which maximizes the capacity available to nodes in the presence of node mobility. The results presented in this paper highlight the need to design future MAC and routing protocols for wireless ad hoc and sensor networks based, not on common-range which is prevalent today, but on variable-range power control     

Towards a classification of energy aware MAC protocols for wireless sensor networks

Power management is an important issue in wireless sensor networks (WSNs) because wireless sensor nodes are usually battery powered, and an efficient use of the available battery power becomes an important concern specially for those applications where the system is expected to operate for long durations. This necessity for energy efficient operation of a WSN has prompted the development of new protocols in all layers of the communication stack. Provided that, the radio transceiver is the most power consuming component of a typical sensor node, large gains can be achieved at the link layer where the medium access control (MAC) protocol controls the usage of the radio transceiver unit. MAC protocols for sensor networks differ greatly from typical wireless networks access protocols in many issues. MAC protocols for sensor networks must have built‐in power conservation, mobility management, and failure recovery strategies. Furthermore, sensor MAC protocols should make performance trade‐off between latency and throughput for a reduction in energy consumption to maximize the lifetime of the network. This is in general achieved through duty cycling the radio transceiver. Many MAC protocols with different objectives were proposed for wireless sensor networks in the literature. Most of these protocols take into account the energy efficiency as a main objective. There is much more innovative work should be done at the MAC layer to address the hard unsolved problems. In this paper, we first outline and discuss the specific requirements and design trade‐offs of a typical wireless sensor MAC protocol by describing the properties of WSN that affect the design of MAC layer protocols. Then, a typical collection of wireless sensor MAC protocols presented in the literature are surveyed, classified, and described emphasizing their advantages and disadvantages whenever possible. Finally, we present research directions and identify open issues for future medium access research. Copyright © 2009 John Wiley & Sons, Ltd.     

A MAC layer protocol for wireless networks with asymmetric links

We introduce AsyMAC, a MAC layer protocol for wireless networks with asymmetric links and study a protocol stack consisting of AsyMAC and the A⁴LP routing protocol. The two protocols are able to maintain connectivity where the standard IEEE 802.11 MAC protocol coupled with either AODV or OLSR routing protocols may loose connectivity. A comparative study shows that AsyMAC improves on two previously proposed protocols’ accuracy in determining the nodes to be silenced to prevent collisions.     

A MAC/Routing cross-layer approach to geographic forwarding in wireless sensor networks

Geographic forwarding is an emerging paradigm for communications between nodes in sensor networks. No exchange of location information is required, and nodes only have to know their own coordinates and those of the destination. Due to the device’s limited processing and storage capabilities, a simplified protocol architecture should be designed so as to make communications in these networks efficient and simple at the same time. Moreover, sensor nodes are battery supplied and, thus, protocol design should be aimed at reducing energy consumption in order to increase network lifetime. In this perspective, one sensor feature recently regarded as of key importance, is the ability to tune the transmission power. This allows the communication range to be varied according to node density and connectivity constraints. In this paper we propose an integrated cross-layer protocol, called MACRO, which integrates MAC and routing layer functionalities in order to support geographic forwarding in wireless sensor networks. In MACRO, a competition is triggered to select the best next relay node while forwarding information to the destination. The competition is based on the evaluation of a weighted progress factor representing the progress towards the destination per unit of transmission power. An analytical paradigm facilitating the most appropriate choice of the next relay is proposed. The proposed solution is assessed through both analysis and ns-2 simulations. Performance results show the advantages of the proposed solution when compared to other geographic forwarding protocols which do not exploit cross-layer features.     

Energy-Efficient Routing Schemes for Underwater Acoustic Networks

Interest in underwater acoustic networks has grown rapidly with the desire to monitor the large portion of the world covered by oceans. Fundamental differences between underwater acoustic propagation and terrestrial radio propagation may call for new criteria for the design of networking protocols. In this paper, we focus on some of these fundamental differences, including attenuation and noise, propagation delays, and the dependence of usable bandwidth and transmit power on distance (which has not been extensively considered before in protocol design studies). Furthermore, the relationship between the energy consumptions of acoustic modems in various modes (i.e., transmit, receive, and idle) is different than that of their terrestrial radio counterparts, which also impacts the design of energyefficient protocols. The main contribution of this work is an in-depth analysis of the impacts of these unique relationships. We present insights that are useful in guiding both protocol design and network deployment. We design a class of energyefficient routing protocols for underwater sensor networks based on the insights gained in our analysis. These protocols are tested in a number of relevant network scenarios, and shown to significantly outperform other commonly used routing strategies and to provide near optimal total path energy consumption. Finally, we implement in ns2 a detailed model of the underwater acoustic channel, and study the performance of routing choices when used with a simple MAC protocol and a realistic PHY model, with special regard to such issues as interference and medium access.     

Actor-oriented directional anycast routing in wireless sensor and actor networks with smart antennas

Current routing protocols in wireless sensor and actor networks (WSANs) shows a lack of unification for different traffic patterns because the communication for sensor to actor and that for actor to actor are designed separately. Such a design poses a challenge for interoperability between sensors and actors. With the presence of rich-resource actor nodes, we argue that to improve network lifetime, the problem transforms from reducing overall network energy consumption to reducing energy consumption of constrained sensor nodes. To reduce energy consumption of sensor nodes, especially in challenging environments with coverage holes/obstacles, we propose that actor nodes should share forwarding tasks with sensor nodes. To enable such a feature, efficient interoperability between sensors and actors is required, and thus a unified routing protocol for both sensors and actors is needed. This paper explores capabilities of directional transmission with smart antennas and rich-resource actors to design a novel unified actor-oriented directional anycast routing protocol (ADA) which supports arbitrary traffic in WSANs. The proposed routing protocol exploits actors as main routing anchors as much as possible because they have better energy and computing power compared to constraint sensor nodes. In addition, a directional anycast routing approach is also proposed to further reduce total delay and energy consumption of overall network. Through extensive experiments, we show that ADA outperforms state-of-the-art protocols in terms of packet delivery latency, network lifetime, and packet reliability. In addition, by offer fault tolerant features, ADA also performs well in challenging environments where coverage holes and obstacles are of concerns.     

Transmit Power Distribution of Wireless Ad-hoc Networks with Topology Control

Topology control and routing protocols are used by designers of wireless packet data networks to lower the node degree, simplify routing and lower the nodes' energy consumption, while preserving strong connectivity. We assume a popular fading channel model and study the impact of several topology control schemes on the transmit power of nodes randomly distributed over a large area according to a Poisson point process, where each node controls the pattern of its one-hop neighbors by independently adjusting its transmit power. We provide the distribution of the transmit power of individual nodes under several different topology control algorithms, allowing designers to estimate the life time of battery energized devices, and the implications of choosing the nodes' peak transmit power. We also allow easy comparisons between several different topology control algorithms with respect to the nodes' power consumption.     

A Novel Energy Efficient and Lifetime Maximization Routing Protocol in Wireless Sensor Networks

The energy consumption is a key design criterion for the routing protocols in wireless sensor networks (WSN). Some of the conventional single path routing schemes may not be optimal to maximize the network lifetime and connectivity. Thus, multipath routing schemes is an optimal alternative to extend the lifetime of WSN. Multipath routing schemes distribute the traffic across multiple paths instead of routing all the traffic along a single path. In this paper, we propose a multipath Energy-Efficient data Routing Protocol for wireless sensor networks (EERP). The latter keeps a set of good paths and chooses one based on the node state and the cost function of this path. In EERP, each node has a number of neighbours through which it can route packets to the base station. A node bases its routing decision on two metrics: state and cost function. It searches its Neighbours Information Table for all its neighbours concerned with minimum cost function. Simulation results show that our EERP protocol minimizes and balances the energy consumption well among all sensor nodes and achieves an obvious improvement on the network lifetime.     

Communication architecture for processing spatio-temporal continuous queries in sensor networks

Wireless sensor networks have revolutionized distributed micro-sensing because of their ease of deployment, ad hoc connectivity and cost-effectiveness. They have also enabled collecting and monitoring data from a very large area or possibly several independent areas geographically separated from each other and such a process is known as spatio-temporal data monitoring. In this paper, we define an energy-aware routing infrastructure that enables distributed query processing and supports processing of spatio-temporal queries within the network. As operator execution demands high computation capability, we propose a possible use of a heterogeneous sensor network where query operators are assigned to sparsely-deployed resource-rich nodes within a dense network of low power sensor nodes. We have designed an adaptive, decentralized, low communication overhead algorithm to determine optimal operator placement on the resource-rich nodes such that data transfer cost in the network is minimized. To the best of our knowledge, this is the first attempt to build an energy-aware communication architecture to enable in-network processing of spatio-temporal queries.     

A Novel Cross-layer Routing Protocol for Increasing Packet Transfer Reliability in Mobile Sensor Networks

In mobile sensor networks (MSNs), sensor data is generally transferred via mobile sensor nodes by multi-hop fashion. Because of the mobility of the nodes in the network, the efficient routing protocols are needed to ensure end-to-end route reliability while incurring minimal power consumption and packet delay. In this study, we developed a new routing protocol to meet these requirements for MSNs based on a cross-layer interaction among five reference layers (application, transport, network, MAC and physical). The proposed protocol primarily exploits the idea of interaction among these five layers all-in-one protocol. Its primary goals are (i) to discover the most reliable route in network, (ii) to sustain the route reliability and (iii) to be energy efficient and delay aware. It has been designed, modeled and simulated by using OPNET Modeler simulation software. The simulation results of the proposed protocol have been compared to three well known routing protocols (i.e., AODV, Leach-Mobile, CBR-Mobile). According to the obtained results, the proposed protocol outperforms its counterparts in terms of route reliability and end-to-end delay performances.     

Bit-per-joule performance of power saving ad hoc networks with a mobile backbone

Energy efficient MAC protocols have been developed for wireless sensor and mobile ad hoc networks so that inactive nodes can transition into sleep state to conserve energy. It has been recognized that maintaining a continuously awake connected dominating set (CDS) serves to reduce the route setup latency. Under the mobile backbone network (MBN) architecture introduced by Rubin et al., a mobile backbone (Bnet) is dynamically constructed to provide a topological covering of the network. The MBN employs a hybrid routing algorithm under which flows that travel a distance longer than a threshold are directed along routes across the Bnet. In turn, a limited span network-wide global route discovery process is applied for routing shorter distance flows. In this paper, we introduce and analyze an MBN based power saving protocol (MBN-PS) that employs this hybrid routing scheme. Under the MBN-PS scheme, dynamically elected backbone nodes are kept awake, while inactive non-backbone nodes can reside in sleep state. We analytically show that, when the number of network flows is above a minimal level, the throughput per watt efficiency attained in an ad hoc network under complete backbone coverage is better than that achieved by a corresponding network that does not form a backbone. We present a model for the calculation of the bit-per-joule performance of the network as a function of the distance threshold. We confirm the validity of our analytical approach through simulations. Using our method, a network designer is able to choose the optimal distance threshold to be used by this scheme, based on traffic loading conditions.     

无线传感器网络的分区异构分簇协议研究

针对无线传感器网络能量受限和路由协议中节点能量消耗不均衡的问题,提出一种新的无线传感器网络的分区异构分簇协议(PHC协议).该协议的核心是将3种不同能量等级的节点根据能量的不同分别部署在不同区域,能量较高的高级节点和中间节点使用聚类技术通过簇头直接传输数据到汇聚点,能量较低的普通节点则直接传输数据到汇聚点.仿真结果表明,该协议通过对节点合理的分配部署,使簇头分布均匀,更好地均衡了节点的能量消耗,延长了网络的稳定期,提高了网络的吞吐量,增强了网络的整体性能.     

Energy efficient multi-channel media access control for dense wireless ad hoc and sensor networks

Traditional single-channel MAC protocols for wireless ad hoc and sensor networks favor energy-efficiency over throughput. More recent multi-channel MAC protocols display higher throughput but less energy efficiency. In this article we propose NAMAC, a negotiator-based multi-channel MAC protocol in which specially designated nodes called negotiators maintain the sleeping and communication schedules of nodes within their communication ranges in static wireless ad hoc and sensor networks. Negotiators facilitate the assignation of channels and coordination of communications windows, thus allowing individual nodes to sleep and save energy. We formally define the problem of finding the optimal set of negotiators (i.e., minimizing the number of selected negotiators while maximizing the coverage of the negotiators) and prove that the problem is NP-Complete. Accordingly, we propose a greedy negotiator-election algorithm as part of NAMAC. In addition, we prove the correctness of NAMAC through a rigorous model checking and analyze various characteristics of NAMAC—the throughput of NAMAC, impact of negotiators on network capacity, and storage and computational overhead. Simulation results show that NAMAC, at high network loads, consumes 36 % less energy while providing 25 % more throughput than comparable state-of-art multi-channel MAC protocols for ad hoc networks. Additionally, we propose a lightweight version of NAMAC and show that it outperforms (55 % higher throughput with 36 % less energy) state-of-art MAC protocols for wireless sensor networks.     

Energy efficient TDMA-based MAC protocol associated with GAF for wireless sensor networks

The design of media access control (MAC) protocol for wireless sensor networks (WSNs) with the idea of cross layer attracts more and more attention. People can improve the MAC protocol by obtaining certain information regarding the network layer and physical layer. This article synthesizes and optimizes certain cross-layer protocols which have existed. On the basis of the routing, topology information in the network layer, and transmission power information in the physical layer, the time slot assignment algorithm has been improved in the MAC layer. By using geographical adaptive fidelity algorithm (GAF) to divide the grids, controlling of transmission power and scheduling the work/sleep duty cycle for sensor nodes, a new MAC protocol has been proposed to decrease energy consumption and enlarge the lifetime of WSNs. Simulation results show that the MAC protocol functions well.