Power-aware routing protocols in ad hoc wireless networks

An ad hoc wireless network has no fixed networking infrastructure. It consists of multiple, possibly mobile, nodes that maintain network connectivity through wireless communications. Such a network has practical applications in areas where it may not be economically practical or physically possible to provide a conventional networking infrastructure. The nodes in an ad hoc wireless network are typically powered by batteries with a limited energy supply. One of the most important and challenging issues in ad hoc wireless networks is how to conserve energy, maximizing the lifetime of its nodes and thus of the network itself. Since routing is an essential function in these networks, developing power-aware routing protocols for ad hoc wireless networks has been an intensive research area in recent years. As a result, many power-aware routing protocols have been proposed from a variety of perspectives. This article surveys the current state of power-aware routing protocols in ad hoc wireless networks.     

Active routing for ad hoc networks

Ad hoc networks are wireless multihop networks whose highly volatile topology makes the design and operation of a standard routing protocol hard. With an active networking approach, one can define and deploy routing logic at runtime in order to adapt to special circumstances and requirements. We have implemented several active ad hoc routing protocols that configure the forwarding behavior of mobile nodes, allowing data packets to be efficiently routed between any two nodes of the wireless network. Isolating a simple forwarding layer in terms of both implementation and performance enables us to stream delay-sensitive audio data over the ad hoc network. In the control plane, active packets permanently monitor the connectivity and setup, and modify the routing state     

Probabilistic analysis of routes on mobile ad hoc networks

The ad hoc network is comprised of mobile nodes without wires or any infrastructures. All data are transmitted from source node to destination node through wireless channels. The ad hoc network is self-organized by ad hoc network routing protocols. Due to the mobility of nodes, the route which is constructed from many proposed ad hoc network routing protocols and comprised of several direct node-to-node links exists only for a certain period. That also means the route is subject to frequent breakages. In this letter, the probabilistic behavior of a constructed route is investigated through simulation and curve fitting. The simulation results show that the probability density function of a route is exponential distribution. The simulation also shows how the time proportion is distributed among different route lengths under a certain scenario. The route is a basic factor in the ad hoc network which operates without any central controller. The characteristics of the route have much influence on the performance of the ad hoc network. Thus the probabilistic analysis provides important implications when we are designing ad hoc network routing protocols and deploying ad hoc networks.     

An optimised resource aware approach to information collection in ad hoc networks

In ad hoc networks there is a need for all-to-one protocols that allow for information collection or “sensing” of the state of an ad hoc network and the nodes that comprise it. Such protocols may be used for service discovery, auto-configuration, network management, topology discovery or reliable flooding. There is a parallel between this type of sensing in ad hoc networks and that of sensor networks. However, ad hoc networks and sensor networks differ in their application, construction, characteristics and constraints. The main priority of sensor networks is for the flow of data from sensors back to a sink, but in an ad hoc network this may be of secondary importance. Hence, protocols suitable to sensor networks are not necessarily suitable to ad hoc networks and vice versa. We propose, Resource Aware Information Collection (RAIC), a distributed two phased resource aware approach to information collection in ad hoc networks. RAIC utilises a resource aware optimised flooding mechanism to both disseminate requests and initialise a backbone of resource suitable nodes responsible for relaying replies back to the node collecting information. RAIC in the process of collecting information from all nodes in an ad hoc network is shown to consume less energy and introduce less overhead compared with Directed Diffusion and a brute force approach. Importantly, over multiple successive queries (in an energy constrained environment), the use of resource awareness allows for the load of relaying to be distributed to those nodes most suitable, thereby extending the lifetime of the network.     

Information for routing in energy-constrained ad hoc networks

In wireless ad hoc networks consisting of battery-limited nodes, communication protocols must be energy-aware to prevent early network failure due to radios exhausting their energy supplies. Incorporating current estimates of battery levels into routing metrics has been shown to reduce the demand on radios with little remaining energy and allow them to participate in the network longer. In addition to knowledge of current battery levels, estimates of how quickly radios are consuming energy may also be helpful in extending network lifetime. We present a family of routing metrics that incorporate a radio’s rate of energy consumption. Simulation results show that the proposed family of metrics performs well under a variety of traffic models and network topologies.     

A location-based routing method for mobile ad hoc networks

Using location information to help routing is often proposed as a means to achieve scalability in large mobile ad hoc networks. However, location-based routing is difficult when there are holes in the network topology and nodes are mobile or frequently disconnected to save battery. Terminode routing, presented here, addresses these issues. It uses a combination of location-based routing (terminode remote routing, TRR), used when the destination is far, and link state-routing (terminode local routing, TLR), used when the destination is close. TRR uses anchored paths, a list of geographic points (not nodes) used as loose source routing information. Anchored paths are discovered and managed by sources, using one of two low overhead protocols: friend assisted path discovery and geographical map-based path discovery. Our simulation results show that terminode routing performs well in networks of various sizes. In smaller networks; the performance is comparable to MANET routing protocols. In larger networks that are not uniformly populated with nodes, terminode routing outperforms, existing location-based or MANET routing protocols.     

Adding sense of spatial locality to routing protocols for mobile ad hoc networks

Recently, there has been an increasing interest in mobile ad hoc networks. In a mobile ad hoc network, each mobile node can freely move around and the network is dynamically constructed by collections of mobile nodes without using any existing network infrastructure. Compared to static networks, it faces many problems such as the inefficiency of routing algorithms. Also, the number of control packets in any routing algorithm increases as the mobile speed or the number of mobile nodes increases. Most of the current routing protocols in ad hoc networks broadcast the control packets to the entire network. Therefore, by reducing the number of control packets, the efficiency of the network routing will be improved. If we know where the destination is, we can beam our search toward that direction. However, without using global positioning systems, how can we do this? Define the range nodes as the 1‐hop or 2‐hop neighbors of the destination node. In this paper, we propose using the range nodes to direct our searches for the destination. It can be combined with the existing routing protocols to reduce the control overhead. We show through simulations that AODV and DSR combined with the range node method outperforms the original AODV and DSR routing protocols in terms of control packets overhead. We also show that the delay introduced in find range nodes is insignificant. Copyright © 2006 John Wiley & Sons, Ltd.     

Maximum-residual multicasting and aggregating in wireless ad hoc networks

Power-aware routing in wireless ad hoc networks has been extensively explored in recent years, and various routing metrics were developed for the prolongation of network lifetime. This work studies power-aware routing so as to maximize the minimum remaining energy of all nodes after routing. This routing metric, referred to as Maximum-Residual Routing, aims at maintaining the minimum remaining energy as high as possible so as to delay the fist failure time of nodes in the network. In this paper, a polynomial-time optimal algorithm is proposed for Maximum-Residual Multicasting. We then show that Maximum-Residual Aggregating is NP{\mathcal{NP}}-hard and that, unless P = NP,{\mathcal{P = NP}}, its minimization version cannot be approximated within a ratio better than (2 − ε) for any ε > 0. The proposed routing algorithm for Maximum-Residual Multicasting can be applied to existing routing protocols, especially those based on the link-state approach. The capability of the algorithm was evaluated by a series of experiments, for which we have very encouraging results in network lifetime and load balance.     

Topology and mobility considerations in mobile ad hoc networks

A highly dynamic topology is a distinguishing feature and challenge of a mobile ad hoc network. Links between nodes are created and broken, as the nodes move within the network. This node mobility affects not only the source and/or destination, as in a conventional wireless network, but also intermediate nodes, due to the network’s multihop nature. The resulting routes can be extremely volatile, making successful ad hoc routing dependent on efficiently reacting to these topology changes.

In order to better understand this environment, a number of characteristics have been studied concerning the links and routes that make up an ad hoc network. Several network parameters are examined, including number of nodes, network dimensions, and radio transmission range, as well as mobility parameters for maximum speed and wait times. In addition to suggesting guidelines for the evaluation of ad hoc networks, the results reveal several properties that should be considered in the design and optimization of MANET protocols.     

Efficient on-demand routing for mobile ad hoc wireless access networks

In this paper, we consider a mobile ad hoc wireless access network in which mobile nodes can access the Internet via one or more stationary gateway nodes. Mobile nodes outside the transmission range of the gateway can continue to communicate with the gateway via their neighboring nodes over multihop paths. On-demand routing schemes are appealing because of their low routing overhead in bandwidth restricted mobile ad hoc networks, however, their routing control overhead increases exponentially with node density in a given geographic area. To control the overhead of on-demand routing without sacrificing performance, we present a novel extension of the ad hoc on-demand distance vector (AODV) routing protocol, called LB-AODV, which incorporates the concept of load-balancing (LB). Simulation results show that as traffic increases, our proposed LB-AODV routing protocol has a significantly higher packet delivery fraction, a lower end-to-end delay and a reduced routing overhead when compared with both AODV and gossip-based routing protocols.     

Efficient flooding with passive clustering-an overhead-free selective forward mechanism for ad hoc/sensor networks

High capacity real-time data communications in sensor networks usually require multihop routing and ad hoc routing protocols. Unfortunately, ad hoc routing protocols usually do not scale well and cannot handle dense situations efficiently. These two issues-scalability and density-are the major limitations when we apply ad hoc routing schemes to sensor networks. Passive clustering (PC) classifies ad hoc/sensor nodes into critical and noncritical nodes without any extra transmission. By 2-b piggybacking and monitoring user traffic (e.g., data polling requests from a sink), PC deploys the clustering structure "for free". Moreover, PC makes even the first flooding as efficient as all subsequent floodings (i.e., no initialization overhead). PC introduces many benefits, including efficient flooding and density adaptation. As a result, PC reduces control overhead of ad hoc routing protocols significantly and, as a consequence, enables ad hoc routing in large, dense sensor networks. The resulting structure can be utilized in cluster-based ad hoc network/sensor networking as well as for active node selection.     

SMORT: Scalable multipath on-demand routing for mobile ad hoc networks

Increasing popularity and availability of portable wireless devices, which constitute mobile ad hoc networks, calls for scalable ad hoc routing protocols. On-demand routing protocols adapt well with dynamic topologies of ad hoc networks, because of their lower control overhead and quick response to route breaks. But, as the size of the network increases, these protocols cease to perform due to large routing overhead generated while repairing route breaks. We propose a multipath on-demand routing protocol (SMORT), which reduces the routing overhead incurred in recovering from route breaks, by using secondary paths. SMORT computes fail-safe multiple paths, which provide all the intermediate nodes on the primary path with multiple routes (if exists) to destination. Exhaustive simulations using GloMoSim with large networks (2000 nodes) confirm that SMORT is scalable, and performs better even at higher mobility and traffic loads, when compared to the disjoint multipath routing protocol (DMRP) and ad hoc on-demand distance vector (AODV) routing protocol.     

Authenticated routing for ad hoc networks

Initial work in ad hoc routing has considered only the problem of providing efficient mechanisms for finding paths in very dynamic networks, without considering security. Because of this, there are a number of attacks that can be used to manipulate the routing in an ad hoc network. In this paper, we describe these threats, specifically showing their effects on ad hoc on-demand distance vector and dynamic source routing. Our protocol, named authenticated routing for ad hoc networks (ARAN), uses public-key cryptographic mechanisms to defeat all identified attacks. We detail how ARAN can secure routing in environments where nodes are authorized to participate but untrusted to cooperate, as well as environments where participants do not need to be authorized to participate. Through both simulation and experimentation with our publicly available implementation, we characterize and evaluate ARAN and show that it is able to effectively and efficiently discover secure routes within an ad hoc network.     

Opportunistic media access control and routing for delay-tolerant mobile ad hoc networks

In delay-tolerant mobile ad hoc networks, motion of network nodes, network sparsity and sporadic density can cause a lack of guaranteed connectivity. These networks experience significant link delay and their routing protocols must take a store-and-forward approach. In this paper, an opportunistic routing protocol is proposed, along with its compatible media access control, for non-real-time services in delay-tolerant networks. The scheme is mobility-aware such that each network node needs to know its own position and velocity. The media access control employs a four-fold handshake procedure to probe the wireless channel and cooperatively prioritize candidate nodes for packet replication. It exploits the broadcast characteristic of the wireless medium to utilize long-range but unreliable links. The routing process seizes opportunities of node contacts for data delivery. It takes a multiple-copy approach that is adaptive with node movements. Numerical results in mobile ad hoc networks and vehicular ad hoc networks show superior performance of the proposed protocol compared with other routing protocols. The mobility-aware media access control and routing scheme exhibits relatively small packet delivery delay and requires a modest amount of total packet replications/transmissions.     

Performance optimisation through EPT-WBC in mobile ad hoc networks

Mobile ad hoc networks are self-organised, infrastructure-less networks in which each mobile host works as a router to provide connectivity within the network. Nodes out of reach to each other can communicate with the help of intermediate routers (nodes). Routing protocols are the rules which determine the way in which these routing activities are to be performed. In cluster-based architecture, some selected nodes (clusterheads) are identified to bear the extra burden of network activities like routing. Selection of clusterheads is a critical issue which significantly affects the performance of the network. This paper proposes an enhanced performance and trusted weight-based clustering approach in which a number of performance factors such as trust, load balancing, energy consumption, mobility and battery power are considered for the selection of clusterheads. Moreover, the performance of the proposed scheme is compared with other existing approaches to demonstrate the effectiveness of the work.     

An efficient load balancing method for ad hoc networks

Routing is the most basic and essential operation of any ad hoc network. A mobile ad hoc network presents many challenges, because of the severe resource limitations such as dynamic and varying topology, lack of centralized control, insecure medium, and limited battery power, among others. Therefore, optimization and conservation is the key to success of any ad hoc network operation. In this paper, we propose and define 2 new metrics for ad hoc networks: bandwidth utilization ratio and load index. These metrics can be used as an indicator to measure and monitor the network usability and to improve its efficiency by efficient load distribution. They can be used to predict the additional load that can be accommodated in the network, without causing any congestion or overflows. We also propose a new load balancing routing scheme for ad hoc networks, called efficient load balancing method. This method tries to offset the load on different paths using load index as a metric. Load index is defined as a measure of a node's degree of involvement in the message routing process, which is indicative of its load. To make this algorithm efficient, we limit our routes to a few efficient ones only. This number of alternate routes used, out of the pool of all available routes, is defined as degree of distribution. Simulation results adequately prove the efficiency of proposed method, vis‐à‐vis 2 other load balancing approaches, and these are verified statistically at 99% confidence interval. A p × q factorial design is used to verify that simulation results are the actual measurements and not due to some unknown errors.     

A routing protocol based on interference-aware and channel-load in multi-radio multi-channel ad hoc networks

Improving capacity and reducing delay are the most challenging topics in wireless ad hoc networks. Nodes that equip multiple radios working on different channels simultaneously permit effective utility of frequency spectrum and can also reduce interference. In this paper, after analyzing several current protocols in Multi-Radio Multi-Channel (MR-MC) ad hoc networks, a new multichannel routing metric called Integrative Route Metric (IRM) is designed. It takes channel load, interflow, and intra-flow interference into consideration. In addition, an MR-MC routing protocol based on Interference-Aware and Channel-Load (MR-IACL) is also presented. The MR-IACL can assign channels and routings for nodes according to channel load and interference degree of links, and optimize channel distribution dynamically to satisfy the features of topology changing and traffic frequent fluctuation during network running. The simulation results show that the new protocol outperforms others in terms of network throughput, end-to-end delay, routing overhead, and network lifetime.     

Performance evaluation of ad hoc routing protocols for military communications

Mobile ad hoc networks (MANETs) are of much interest to both the research community and the military because of the potential to establish a communication network in any situation that involves emergencies. Examples are search‐and‐rescue operations, military deployment in hostile environments, and several types of police operations. One critical open issue is how to route messages considering the characteristics of these networks. The nodes act as routers in an environment without a fixed infrastructure, the nodes are mobile, the wireless medium has its own limitations compared to wired networks, and existing routing protocols cannot be employed, at least without modifications. Over the last few years, a number of routing protocols have been proposed and enhanced to address the issue of routing in MANETs. It is not clear how those different protocols perform under different environments. One protocol may be the best in one network configuration but the worst in another. This article provides an analysis and performance evaluation of those protocols that may be suitable for military communications. The evaluation is conducted in two phases. In the first phase, we compare the protocols based on qualitative metrics to locate those that may fit our evaluation criteria. In the second phase, we evaluate the selected protocols from the first phase based on quantitative metrics in a mobility scenario that reflects tactical military movements. The results disclose that there is no routing protocol in the current stage without modifications that can provide efficient routing to any size of network, regardless of the number of nodes and the network load and mobility. Copyright © 2011 John Wiley & Sons, Ltd.     

Capacity regions for wireless ad hoc networks

We define and study capacity regions for wireless ad hoc networks with an arbitrary number of nodes and topology. These regions describe the set of achievable rate combinations between all source-destination pairs in the network under various transmission strategies, such as variable-rate transmission, single-hop or multihop routing, power control, and successive interference cancellation (SIC). Multihop cellular networks and networks with energy constraints are studied as special cases. With slight modifications, the developed formulation can handle node mobility and time-varying flat-fading channels. Numerical results indicate that multihop routing, the ability for concurrent transmissions, and SIC significantly increase the capacity of ad hoc and multihop cellular networks. On the other hand, gains from power control are significant only when variable-rate transmission is not used. Also, time-varying flat-fading and node mobility actually improve the capacity. Finally, multihop routing greatly improves the performance of energy-constraint networks.     

Variable power broadcast using local information in ad hoc networks

Network wide broadcast is a frequently used operation in ad hoc networks. Developing energy efficient protocols to reduce the overall energy expenditure in network wide broadcast can contribute toward increasing the longevity of ad hoc networks. Most of the existing work in energy efficient broadcast protocols use either a fixed transmission power model or assume global knowledge of the entire network at each node. Variable power broadcast with local knowledge has recently been proposed as a promising alternative approach for network wide broadcast in ad hoc networks.

In this paper, we present a novel approach, called INOP, for network wide broadcast. INOP is a variable power broadcast approach that uses local (two-hop neighborhood) information. INOP utilizes a novel technique for determining the transmission power level at each transmitting node. We also propose two alternative methods to cover the nodes that are not covered by the transmission of the source or a retransmitting node.

Our simulation based evaluations show that, compared to other approaches, INOP achieves better results in terms of energy efficiency, and competes with and exceeds other approaches in terms of a number of other performance metrics including traffic overhead, coverage, and convergence time. Based on these results, we can conclude that INOP improves the current state-of-the-art approaches for energy efficient broadcast in ad hoc networks.