Scalable geographic routing algorithms for wireless ad hoc networks

The design of efficient routing protocols for dynamical changing network topologies is a crucial part of building power-efficient and scalable ad hoc wireless networks. If position information is available due to GPS or some kind of relative positioning technique, a promising approach is given by geographic routing algorithms, where each forwarding decision is based on the positions of current, destination, and possible candidate nodes in vicinity only. About 15 years ago heuristic greedy algorithms were proposed, which in order to provide freedom from loops might fail even if there is a path from source to destination. In recent years planar graph traversal has been investigated as one possible strategy to recover from such greedy routing failures. This article provides a tutorial for this class of geographic routing algorithms, and discusses recent improvements to both greedy forwarding and routing in planar graphs.     

An ellipse-guided routing algorithm in wireless sensor networks

In wireless sensor networks, sensor nodes are deployed to collect data, perform calculations, and forward information to either other nodes or sink nodes. Recently, geographic routing has become extremely popular because it only requires the locations of sensor nodes and is very efficient. However, the local minimum phenomenon, which hinders greedy forwarding, is a major problem in geographic routing. This phenomenon is attributed to an area called a hole that lacks active sensors, which either prevents the packet from being forwarded to a destination node or produces a long detour path. In order to solve the hole problem, mechanisms to detect holes and determine landmark nodes have been proposed. Based on the proposed mechanisms, landmark-based routing was developed in which the source node first sends a packet to the landmark node, and the landmark node then sends the packet to the destination. However, this approach often creates a constant node sequence, causing nodes that perform routing tasks to quickly run out of energy, thus producing larger holes. In this paper, a new approach is proposed in which two virtual ellipses are created with the source, landmark, and destination nodes. Then guide the forwarding along the virtual ellipses. Furthermore, a recursive algorithm is designed to ensure a shortcut even if there are multiple holes or a hole has multiple landmarks. Thus, the proposed approach improves both geographic routing and energy efficiency routing. Simulation experiments show that the proposed approach increases the battery life of sensor nodes, lowers the end-to-end delay, and generates a short path.     

A survey on position-based routing in mobile ad hoc networks

We present an overview of ad hoc routing protocols that make forwarding decisions based on the geographical position of a packet's destination. Other than the destination's position, each node need know only its own position and the position of its one-hop neighbors in order to forward packets. Since it is not necessary to maintain explicit routes, position-based routing does scale well even if the network is highly dynamic. This is a major advantage in a mobile ad hoc network where the topology may change frequently. The main prerequisite for position-based routing is that a sender can obtain the current position of the destination. Therefore, previously proposed location services are discussed in addition to position-based packet forwarding strategies. We provide a qualitative comparison of the approaches in both areas and investigate opportunities for future research     

Greedy Routing with Anti-Void Traversal for Wireless Sensor Networks

The unreachability problem (i.e., the so-called void problem) that exists in the greedy routing algorithms has been studied for the wireless sensor networks. Some of the current research work cannot fully resolve the void problem, while there exist other schemes that can guarantee the delivery of packets with the excessive consumption of control overheads. In this paper, a greedy anti-void routing (GAR) protocol is proposed to solve the void problem with increased routing efficiency by exploiting the boundary finding technique for the unit disk graph (UDG). The proposed rolling-ball UDG boundary traversal (RUT) is employed to completely guarantee the delivery of packets from the source to the destination node under the UDG network. The boundary map (BM) and the indirect map searching (IMS) scheme are proposed as efficient algorithms for the realization of the RUT technique. Moreover, the hop count reduction (HCR) scheme is utilized as a short-cutting technique to reduce the routing hops by listening to the neighbor's traffic, while the intersection navigation (IN) mechanism is proposed to obtain the best rolling direction for boundary traversal with the adoption of shortest path criterion. In order to maintain the network requirement of the proposed RUT scheme under the non-UDG networks, the partial UDG construction (PUC) mechanism is proposed to transform the non-UDG into UDG setting for a portion of nodes that facilitate boundary traversal. These three schemes are incorporated within the GAR protocol to further enhance the routing performance with reduced communication overhead. The proofs of correctness for the GAR scheme are also given in this paper. Comparing with the existing localized routing algorithms, the simulation results show that the proposed GAR-based protocols can provide better routing efficiency.     

Greedy Anti-Void Routing Protocol for Wireless Sensor Networks

The unreachability problem (i.e. the so-called void problem) which exists in the greedy routing algorithms has been studied for the wireless sensor networks. However, most of the current research work can not fully resolve the problem (i.e. to ensure the delivery of packets) within their formulation. In this letter, the greedy anti-void routing (GAR) protocol is proposed, which solves the void problem by exploiting the boundary finding technique for the unit disk graph (UDG). The proposed rolling-ball UDG boundary traversal (RUT) is employed to completely guarantee the delivery of packets from the source to the destination node. The proofs of correctness for the proposed GAR protocol are also given at the end of this letter.     

A fast and reliable routing technique for wireless mesh networks

In wireless mesh networks (WMNs), real time communications (e.g., Voice over IP (VoIP) and interactive video communications) may often be interrupted as packets are frequently lost or delayed excessively. This usually happens due to the unreliability of wireless links or buffer overflows along the routing paths. The mesh connectivity within the WMN enables the capability to enhance reliability and reduce delay for such applications by using multiple paths for routing their packets. The vital components in multi‐path routing for achieving this are the pre‐determined formation of paths and the technique that the paths are deployed for packet traversal. Therefore, we propose a novel multi‐path routing protocol by introducing a new multi‐path organization and a traffic assignment technique. The designed technique dubbed as FLASH (Fast and reLiAble meSH routing protocol) discovers one primary path between a pair of source and destination based on a new proposed metric, and thereafter selects mini‐paths, which connect pairs of intermediate nodes along the primary path. The primary path and mini‐paths are concurrently deployed, as multiple copies of packets are routed through. This technique compensates for possible outage at intermediate wireless nodes or their corresponding wireless links along the primary path. Routing along mini‐paths is performed in such a way that redundant copies do not cause an excessive congestion on the network. The effectiveness of the proposed scheme is evaluated analytically and through extensive simulations under various load conditions. The results demonstrate the superiority of the proposed multi‐path organization in terms of reliability and satisfactory achievements of the protocol in enhancing delay and throughput compared to the existing routing protocols, especially for long distances and in congested conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

Power and cost aware localized routing with guaranteed delivery in unit graph based ad hoc networks

In a localized routing algorithm, each node currently holding a message makes forwarding decision solely based on the position information about itself, its neighbors and destination. In a unit graph, two nodes can communicate if and only if the distance between them is no more than the transmission radius, which is the same for each node. This paper proposes localized routing algorithms, aimed at minimizing total power for routing a message or maximizing the total number of routing tasks that a network can perform before a partition. The algorithms are combinations of known greedy power and/or cost aware localized routing algorithms and an algorithm that guarantees delivery. A shortcut procedure is introduced in later algorithm to enhance its performance. Another improvement is to restrict the routing to nodes in a dominating set. These improvements require two‐hop knowledge at each node. The efficiency of proposed algorithms is verified experimentally by comparing their power savings, and the number of routing tasks a network can perform before a node loses all its energy, with the corresponding shortest weighted path algorithms and localized algorithms that use fixed transmission power at each node. Significant energy savings are obtained, and feasibility of applying power and cost‐aware localized schemes is demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.     

Boundary Mapping and Boundary-State Routing (BSR) in Ad Hoc Networks

This paper presents a geographic routing protocol, boundary state routing (BSR), which consists of two components. The first is an improved forwarding strategy, greedy-bounded compass, which can forward packets around concave boundaries, where the packet moves away from the destination without looping. The second component is a boundary mapping protocol (BMP), which is used to maintain link state information for boundaries containing concave vertices. The proposed forwarding strategy greedy-bounded compass is shown to produce a higher rate of path completion than Greedy forwarding and significantly improves the performance of greedy perimeter state routing (GPSR) in sparse networks when used in place of greedy forwarding. The proposed geographic routing protocol BSR is shown to produce significant improvements in performance in comparison to GPSR in sparse networks due to informed decisions regarding the direction of boundary traversal at local minima.     

机会网络中基于摆渡节点与簇节点相互协作的路由机制

机会网络是一种不需要在源节点和目的节点之间存在完整路径,利用节点移动带来的相遇机会实现网络通信的延迟容忍自组织网络,它以“存储-携带-处理-转发”的模式进行.为实现互不相交簇间的信息传输,本文设计了一种带阈值的簇移动模型CMMT,并提出了一种基于摆渡（Ferry）节点与簇节点协作的路由算法（CBSW）.该算法减少了冗余的通信和存储开销,以及在Spray阶段簇节点没有遇到目的节点或摆渡节点,进入Wait阶段携带消息的节点采用直接分发方式只向目的节点传输等问题.仿真实验表明,CBSW算法能够增加传输成功率,减少网络开销和传输延迟.     

On-demand loop-free routing with link vectors

We present the on-demand link vector (OLIVE) protocol, a routing protocol for ad hoc networks based on link-state information that is free of routing loops and supports destination-based packet forwarding. Routers exchange routing information reactively for each destination in the form of complete paths, and each node creates a labeled source graph based on the paths advertised by its neighbors. A node originates a broadcast route request (RREQ) to obtain a route for a destination for which a complete path does not exist in its source graph. When the original path breaks, a node can select an alternative path based on information reported by neighbors, and a node can send a unicast RREQ to verify that the route is still active. A node that cannot find any alternate path to a destination sends route errors reliably to those neighbors that were using it as next hop to the destination. Using simulation experiments in ns2, OLIVE is shown to outperform dynamic source routing, ad hoc on-demand distance vector, optimized link-state routing protocol, and topology broadcast based on reverse-path forwarding, in terms of control overhead, throughput, and average network delay, while maintaining loop-free routing with no need for source routes.     

Void traversal for efficient non-planar geometric routing

Geometric routing provides a scalable and efficient way to route messages in ad hoc networks if extensive routing information is unavailable. Such algorithms require a planar graph to guarantee message delivery. The routing techniques for such guarantee usually center around the traversal of planar faces of the graph. However, in realistic wireless networks existing planarization methods, if at all applicable, tend to require extensive local storage or result in suboptimal route selection. In this paper we study an alternative approach of translating the algorithms themselves to be able to route messages over voids in non-planar graphs. We prove sufficient memory requirements for such translations. We then translate several well-known planar geometric routing algorithms and evaluate their performance in both static and mobile networks.     

Estimating Hop Counts in Position Based Routing Schemes for Ad Hoc Networks

The recent availability of small, inexpensive low power GPS receivers and techniques for finding relative coordinates based on signal strengths, and the need for the design of power efficient and scalable networks, provided justification for applying position based routing methods in ad hoc networks. A number of such algorithms were developed recently. They are all based on three greedy schemes, applied when the forwarding node is able to advance the message toward destination. In this paper we show that the hop count, that is the number of transmissions needed to route a message from a source node to a destination node can be estimated reasonably accurately (in random unit graphs with uniform traffic), with less than 10%, 5% and 7% error for directional (compass), distance (greedy) and progress (MFR) based schemes, respectively, for 100 nodes with average degrees between 5 and 14, without experiments. Our results are derived from statistical observations regarding expected position of forwarding neighbor.     

无线传感器网络中基于网络嵌入的弱贪婪路由协议

贪婪路由可以划分为强贪婪和弱贪婪2种路由方式。为了解决目前研究工作中弱贪婪路由协议需要地理位置信息,而强贪婪路由协议需要设计满足贪婪属性的网络嵌入图的问题;同时为了降低操作复杂性,减少能量消耗,提出了一种轻量级的基于树的网络嵌入图(TNEG)构建方法。在基于树的网络嵌入图上,设计了具有局部单调性的贪婪函数,并提出了2个路由规则,然后设计了弱贪婪路由协议TGR和基于双树嵌入的路由协议biTGR。模拟实验表明所提路由协议在路径长度和网络负载等性能上具有明显的优势。     

Mobility control for achieving optimal configuration in wireless sensor networks

Recent work in wireless sensor networks, or simply called WSNs, has drawn attention to the mobility capability of each node. In Stojmenovic and Lin (IEEE Trans Parallel Distrib Syst 12: 1023–1032, 2001), it is proved that the optimal positions of the relay nodes along a single active flow must lie entirely on the line between the source and destination with each node spaced evenly along such a line. Based on this, we propose two practical solutions to control the relay nodes in WSNs to approach their optimal positions in the local relative coordinate system. One uses one-hop neighbor information and the other one uses two-hop neighbor information. Basically, each relay node will approach the midpoint on the line composed of neighbors. For the latter control scheme, we also discuss its different implementation with outdated two-hop neighbor information (lagged by one-round neighbor information exchange and update). This is an improvement since given nodes only reuse the two-hop neighbor information previously saved at its one-hop neighbors and does not require any extra neighbor information collection. All the new methods prevent oscillations by demanding minimal moving distance per round (MDPR), otherwise the node does not move. Unlike the one presented in Goldenberg et al. (Proceedings of the 5th ACM International Symposium on Mobile Ad Hoc Networking and Computing (Mobihoc’04), pp 163–174 2004) using only one-hop neighbor information, our methods will converge more quickly. The experimental results show a substantial improvement on the speed of achieving the optimal configuration and the total moving distance of nodes.     

Link-State-Based Algorithms for Dynamic Routing in All-Optical Networks with Ring Topologies

The increased usage of large bandwidth in optical networks raises the problems of efficient routing to allow these networks to deliver fast data transmission with low blocking probabilities. Due to limited optical buffering in optical switches and constraints of high switching speeds, data transmitted over optical networks must be routed without waiting queues along a path from source to destination. Moreover, in optical networks deprived of wavelength converters, it is necessary for each established path to transfer data from source to destination by using only one wavelength. To solve this NP-hard problem, many algorithms have been proposed for dynamic optical routing like Fixed-Paths Least Congested (FPLC) routing or Least Loaded Path Routing (LLR). This paper proposes two heuristic algorithms based on former algorithms to improve network throughput and reduce blocking probabilities of data transmitted in all-optical networks with regard to connection costs. We also introduce new criteria to estimate network congestion and choose better routing paths. Experimental results in ring networks show that both new algorithms achieve promising performance.     

Channel Adaptive Shortest Path Routing for Ad Hoc Networks

1　IntroductionAdhocnetworksareformedwithoutrequiringthepreexistinginfrastructureorcentralizedadminis tration ,incontrasttocellularnetworks.Asidefromtheoriginalmilitaryapplication ,ithasapplicationinpublicsafetyandcommercialareas,butadaptiveprotocolsarerequiredinorderforthemtodoso .Twoimportantcharacteristicsofacommunicationlinkinadhocnetworksareitsunreliabilityanditsvariability .Thelinksinsuchanetworkareunreli ablebecauseoffading ,interference,noise,andper hapsthefailureofthetransmittingorrec…     

Routing with hexagonal virtual coordinates in wireless sensor networks

Using geographic routing, like GPSR, is efficient for ad hoc and wireless sensor networks, but it requires that nodes be aware of their physical positions. However, if there are holes in the network, routing across them using GPSR will lead to a lot of overloaded nodes on their boundaries. In this paper, we propose a distributed protocol, named hexagonal virtual coordinate (HVC), for constructing a virtual coordinate system. After the HVC is constructed, the nodes in the network will be aware of the relative coordinates among the landmarks through the HVC chart. Based on the HVC chart, a source node can find an auxiliary routing path (ARP) to indicate the direction of the journey from the source to the destination. Simulation results show that our protocol can support geographic routing efficiently, and the landmarks found by our protocol are uniformly located in the network even if some holes exist within it. In addition, our protocol is resilient to various network shapes and can find a load balancing routing path to the destination even if this path comes across holes in the network. Copyright © 2008 John Wiley & Sons, Ltd.     

无线网络中一种高QoS保证的路由协议研究

随着多媒体及实时应用的普及,在移动自组网中为业务流提供服务质量保证现已成为研究热点.提出一种在大规模移动自组网中提供服务质量保证的分段式路由协议.该协议采用直线逼近的方法,逐段建立满足带宽要求且延迟小的路径,并选择到源节点和目的节点连线距离最近的节点作为转发节点.通过分段、独立地维护路由,减小了路由维护的代价,提高了可扩展性.模拟结果表明该路由协议具有路由成功率高、路径短和延迟小等特点.     

A new distributed route selection approach for channelestablishment in real-time networks

We propose a new distributed route selection approach, called parallel probing, for real-time channel establishment in a point-to-point network. The existing distributed routing algorithms fall into two major categories: preferred neighbor based or flooding based. The preferred neighbor approach offers a better call acceptance rate, whereas the flooding approach is better in terms of call setup time and routing distance. The proposed approach attempts to combine the benefits of both preferred neighbor and flooding approaches in a way to improve all the three performance metrics simultaneously. This is achieved by probing k different paths in parallel, for a channel, by employing different heuristics on each path. Also, the proposed approach uses a notion called intermediate destinations (IDs), which are subset of nodes along the least-cost path between source and destination of a call, in order to reduce the excessive resource reservations while probing for a channel by releasing unused resources between IDs and initiating parallel probes at every ID. Further, it has the flexibility of adapting to different load conditions by its nature of using different heuristics in parallel, and hence, a path found for a channel would have different segments (a segment is a path between two successive IDs), and each of these segments would very well be selected by different heuristics. The effectiveness of the proposed approach has been studied through simulation for well-known network topologies for a wide range of quality-of-service and traffic parameters. The simulation results reveal that the average call acceptance rate offered by the proposed route-selection approach is better than that of both the flooding and preferred neighbor approaches, and the average call setup time and routing distance offered by it are very close to that of the flooding approach     

QoS routing based on mobile agent for LEO satellite IP networks

Current quality of service (QoS) routing schemes for low earth orbit (LEO) satellites IP networks either neglect the varying population density or fail to guarantee end-to-end delay. As a remedy, QoS routing protocol based on mobile agent (QoSRP-MA) is proposed. QoSRP-MA is a source-based routing protocol. Once connection requests arrive, QoS mobile agents are dispatched from ingress satellite to explore routes, which migrate using satellite routing tables. Upon arriving in egress satellite, QoS mobile agents migrate back towards ingress satellite to reserve bandwidth. To construct satellite routing tables, load balancing routing algorithm based on mobile agent (LBRA-MA) is presented. In LBRP-MA, at regular intervals mobile agents launched on all satellites migrate autonomously to evaluate path cost and update routing tables. Moreover, path cost between source and destination is evaluated considering satellite geographical position as well as inter-satellite link (ISL) cost. Furthermore, ISL congestion index is considered to update routing table. Through simulations on a Courier-like constellation, it shows that QoSRP-MA can achieve guaranteed end-to-end delay bound with higher throughput, lower connection failing ratio and signaling overhead compared to high performance satellite routing (HPSR) scheme.