Bounding the locality of distributed routing algorithms

In providing new telecommunication services, the requisition for quality of network is more and more popular and sophisticated with high bandwidth, small value of delay time or packet loss etc. To assure the quality of network, the localized routing schemes have recently been researched as a promising alternative to the currently deployed global QoS routing schemes. Different from the traditional QoS routing algorithms which use global state information, the localized routing algorithms use local information collected from source node to make routing decisions. These localized routing algorithms can be solutions to meet the demand of telecom market in the near future. In this paper, we study and propose one model of localized QoS routing algorithm, which uses distributed routing type to route flows. We perform it with experiments, compare and realize the more considerable performance of this algorithm than other algorithms, which use the same conditions of simulation. From that, we imply that localized QoS routing algorithm using distributed routing works more effectively than other types of routing algorithm.

In a localized routing algorithm, node A currently holding the message forwards it based on the location of itself, its neighboring nodes and destination. We propose to use depth first search (DFS) method for routing decisions. Each node A, upon receiving the message for the first time, sorts all its neighbors according to a criteria such as their distance to destination and uses that order in DFS algorithm. It is the first localized algorithm that guarantees delivery for (connected) wireless networks modeled by arbitrary graphs, including inaccurate location information. We then propose the first localized QoS routing algorithm for wireless networks. It performs DFS routing algorithm after edges with insufficient bandwidth or insufficient connection time are deleted from the graph, and attempts to minimize hop count. This is also the first paper to apply GPS in QoS routing decisions, and to consider the connection time (estimated lifetime of a link) as a QoS criterion. The average length of measured QoS path in our experiments, obtained by DFS method, was between 1 and 1.34 times longer than the length of QoS path obtained by shortest path algorithm. The overhead is considerably reduced by applying the concept of internal nodes.

The scheme of Quality of Service (QoS) routing algorithms based on local state information has recently been proposed as an alternative approach to the traditional QoS routing algorithms. By implementing this localized QoS routing algorithm, each source node predetermines and maintains a set of candidate paths for each destination. These sets of paths will help the source node to decide the most appropriate path for a connection request. Hence, it helps to avoid the problems associated with the maintenance of the global network state information. In this paper, we propose a new and effective localized QoS routing algorithm, compare its performance with those of other localized algorithms and a traditional QoS routing algorithm under the same type of network topology, QoS requirements and traffic patterns. The simulations results show that our proposed algorithm can perform better than other routing algorithms. DOI: 10.32913/rd-ict.vol3.no14.258

We present a deterministic local routing algorithm that is guaranteed to find a path between any pair of vertices in a half-$\theta_6$-graph (the half-$\theta_6$-graph is equivalent to the Delaunay triangulation where the empty region is an equilateral triangle). The length of the path is at most $5/\sqrt{3} \approx 2.887$ times the Euclidean distance between the pair of vertices. Moreover, we show that no local routing algorithm can achieve a better routing ratio, thereby proving that our routing algorithm is optimal. This is somewhat surprising because the spanning ratio of the half-$\theta_6$-graph is 2, meaning that even though there always exists a path whose length is at most twice the Euclidean distance, we cannot always find such a path when routing locally. Since every triangulation can be embedded in the plane as a half-$\theta_6$-graph using $O(\log n)$ bits per vertex coordinate via Schnyder's embedding scheme [W. Schnyder, Embedding planar graphs on the grid, in Proceedings of the 1st Annual ACM--SIAM Symposium on Discrete Algorithms (SODA 1990), ACM, New York, SIAM, Philadelphia, 1990, pp. 138--148], our result provides a competitive local routing algorithm for every such embedded triangulation. Finally, we show how our routing algorithm can be adapted to provide a routing ratio of $15/\sqrt{3} \approx 8.660$ on two bounded degree subgraphs of the half-$\theta_6$-graph.

A geometric graph in the plane is angle-monotone of width $\gamma$ if every pair of vertices is connected by an angle-monotone path of width $\gamma$, a path such that the angles of any two edges in the path differ by at most $\gamma$. Angle-monotone graphs have good spanning properties. We prove that every point set in the plane admits an angle-monotone graph of width $90^\circ$, hence with spanning ratio $\sqrt 2$, and a subquadratic number of edges. This answers an open question posed by Dehkordi, Frati and Gudmundsson. We show how to construct, for any point set of size $n$ and any angle $\alpha$, $0 < \alpha < 45^\circ$, an angle-monotone graph of width $(90^\circ+\alpha)$ with $O(\frac{n}{\alpha})$ edges. Furthermore, we give a local routing algorithm to find angle-monotone paths of width $(90^\circ+\alpha)$ in these graphs. The \emph{routing ratio}, which is the ratio of path length to Euclidean distance, is at most $1/\cos(45^\circ + \frac{\alpha}{2})$, i.e., ranging from $\sqrt 2 \approx 1.414$ to $2.613$. For the special case $\alpha = 30^\circ$, we obtain the full-$\Theta_6$-graph and our routing algorithm achieves the known routing ratio 2 while finding angle-monotone paths of width $120^\circ$.

Localised quality of service (QoS) routing has recently been proposed as a viable alternative approach to traditional QoS routing algorithms that use global state information. In this approach, problems associated with maintaining global state information are avoided by having the source nodes to infer the network QoS state based on flow blocking statistics collected locally, and perform flow routing using this localised view of the network QoS state. A credit based routing algorithm (CBR) which is a simple yet effective localised QoS routing algorithm is introduced. Its performance is compared against the localised proportional sticky routing (PSR) algorithm using different types of network topologies, QoS requirements and traffic patterns and under a wide range of traffic loads. Extensive simulations show that the algorithm outperforms the PSR scheme while maintaining the same level of adaptivity and stability. Its performance is also compared against the global widest-shortest path algorithm (WSP) and it is shown that CBR gives a comparable performance with better time complexity and very low communication overhead.

In this paper, we investigate how to design energy-efficient localized routing in a large-scale three-dimensional (3D) wireless network. Several 3D localized routing protocols were proposed to seek either energy efficiency or delivery guarantee in 3D wireless networks. However, recent results [1, 2] showed that there is no deterministic localized routing algorithm that guarantees either delivery of packets or energy efficiency of its routes in 3D networks. In this paper, we focus on design of a simple localized routing method which can provide energy efficiency with high probability in a randomly deployed 3D network. In particular, we extend our previous routing method designed for 2D networks [3] to 3D networks. The proposed 3D routing method is a simple variation of 3D greedy routing and can guarantee energy efficiency of its paths with high probability in random 3D networks. We also study its asymptotic critical transmission radius to ensure the packet delivery with high probability in random 3D networks. Simulation results confirm our theoretical results.KeywordsDelivery RatioForwarding NodeRestricted RegionTransmission RadiusStretch FactorThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Privacy is becoming a major issue in ad hoc networks. In this paper, using pseudonimity for achieving communication anonymity in networks that apply geographic-routing algorithms is explored. An Anonymous Receiver-Contention POsitioning (ARCPO) routing algorithm is proposed. Node identities (IDs) are kept anonymous. Pseudonyms, i.e., the positions of destinations, are used for data-packet delivery. The anonymity for a destination relies on the difficulty of matching its position to its ID by any observer. Position servers that provide node position information act as trusted third parties and handle identity management. Node mobility makes the use of the pseudonym momentary, and therefore can further improve privacy. The anonymity for the source and intermediate nodes in the path is also achieved because they are not required to reveal any identity information. A receiver-contention mechanism is proposed so that a next hop can be generated without local position information exchange, which otherwise may lead to severe privacy degradation. Analysis and simulation show that while ARCPO guarantees anonymous communication in ad hoc networks, its routing performance degrades moderately compared with other position routing algorithms.

In order to improve the global localization accuracy, the influence of gross errors and the real-time localization information in the cooperative localization of autonomous underwater vehicle system under clutter interference, a local information fusion algorithm based on information gain is proposed. In this paper, the reliability of each measurement information is investigated from information entropy theory, and the multi-group local filtering information of the multi-master underwater vehicle is optimized. Taking the information gain as the weight, the multi-group filtering results are fused to generate the localization information measured from the AUV. A parallel structure of local information filtering and information gain weighting method is proposed, which utilizes a real-time update mechanism to ensure that the input values of the information weighting algorithm come from the latest local filtering output values. In the end, simulation results demonstrate that this method can effectively reduce the absolute error of local filtering and improve the localization accuracy.

A multi-dual ring connected shuffle network is an optical multichannel multihop architecture proposed for wide area networks (WAN). With a simple fixed routing algorithm, this network architecture can achieve better performance than the Perfect ShuffleNet. In this paper, we propose a simple adaptive routing scheme which can achieve an even better performance. The adaptive routing scheme can quickly disperse packets away from congested portions of the network. Unlike centralized routing algorithms, the distributed routing algorithm uses only local state information and does not require a priori knowledge of the traffic patterns. Also, in contrast with some adaptive routing algorithms proposed for the Perfect ShuffleNet, the routing algorithm can distribute some of the traffic over less busy channels without increasing the length of the path. Moreover, in the case of network link failure, the adaptive routing scheme can direct the traffic around the 'trouble' area, which makes the network survivable. Since the whole idea of the scheme is to distribute traffic evenly among all the channels as much as possible, it can reduce the maximum traffic intensity on each channel, thus decreasing the size of pre-allocated buffer. All these characters make it very suitable for optical network architectures. The deloading factor is used in assessing the performance. Static simulations are performed under the worst condition and the most likely scenarios. The results support the preceding statements. The ideas presented here may be used for other optical WAN architectures, as long as each metropolitan area network is multiconnected in a ring topology.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Energy preservation for effective WSN applications is one of the major challenges, as the small sensor nodes have very limited power, storage, communication and computing resources. The sensors remain unattended, and after deployment, rechargeable batteries are almost difficult. The algorithm proposed to pick a nearest hop node based on the token-ring algorithm, compared with the other current S-MAC, T-MAC and HEED algorithms, which pick the next hop node based on parameters such as shortest-path, maximum residual power or probability. More specifically, it is easier to reduce the total power consumption on a multihop route when driving by carefully choosing suitable intermediate nodes. The combination of cluster-based routing and containerized WSN routing algorithms is proposed to be used as an Advanced Energy Efficient Sensor-based MAC (AES-MAC) protocol. The routing process involves the maintenance of routing and routing. The illustrations show a simple, distributed, localized routing algorithm, which can be easily implemented for various practical applications.

This chapter proposed a collaborative peer network application called 6Search (6S) to address the scalability limitations of centralized search engines. Each peer crawls the Web in a focused way, guided by its user’s information context. Through this approach, better (distributed) coverage can be achieved. Each peer also acts as a search “servent” (server + client) by submitting and responding to queries to/from its neighbors. This search process has no centralized bottleneck. Peers depend on a local adaptive routing algorithm to dynamically change the topology of the peer network and search for the best neighbors to answer their queries. We present and evaluate learning techniques to improve local query routing. We validate prototypes of the 6S network via simulations with model users based on actual Web crawls. We find that the network topology rapidly converges from a random network to a small world network, with clusters emerging from user communities with shared interests. We finally compare the quality of the results with those obtained by centralized search engines such as Google.

Routing algorithms for large-scale sensor networks should be capable of finding energy efficient paths to prolong the lifetime of the networks in a decentralized manner. With this respect, Ant System has several proper characteristics for routing algorithm in large-scale wireless sensor networks. First, its distributed mechanism enables routing algorithm to find a solution with only local information and be robust for uncertainties in wireless sensor networks. Second, the framework of the Ant System is proper to solve dynamic problems such as routing problem. Transition probability in Ant System can be used to estimate how good a given routing path is. Capturing these features, this work proposes two Ant Systems based routing algorithms, which are AS-RWSNs (Ant System for Routing in Wireless Sensor Networks) and SAAS-RWSN (Structure-Aware AS-RWSN). The AS-RWSN applies the original Ant System to routing algorithm for wireless sensor network and SAAS-RSN upgrades AS-RWSN with considering properties of network structure such as degree of node. In SAAS-RSN, sensors with high node degree have high data traffic since they have more routing paths. Consequently, SAAS-RSN achieves an energy balance over sensor network through this routing scheme. We demonstrate the effectiveness of the proposed algorithms by comparing three existing routing algorithms.

Wireless Ad hoc Sensor Networks (WASNs) are self organizing, self-configuring and multi-hop wireless networks, in which each node communicates with other nodes directly or indirectly through intermediate nodes without any infrastructure. Besides these characteristics challenges like limited energy, dynamic topology, low bandwidth and security exists. The arrangement of nodes in WASN is called topology which changes dynamically with respect to time and mobility. Energy conservation is a major challenge because of the limited battery resource. In order to conserve energy in the network layer many techniques were used. These techniques can be classified mainly into two categories. The first technique is making small number of nodes awake to transfer bulk amount of data and to maintain the network connectivity and making the remaining nodes to be in sleep mode to conserve energy. This technique is effective for low traffic conditions. In the second technique, topology in the network is controlled by power control technique. This technique is effective for high data traffic. To conserve energy in an efficient manner, a Dynamic Traffic Energy Efficient Topology (DTEET) dynamically adjusts network topology for various network traffic conditions in WASN either in low traffic or high traffic is proposed. And the proposed protocol DTEET is stimulated by using AODV as routing protocol using network simulator ns2.34 and compared with AODV and DSR [1,2]. The simulation results revealed that the proposed scheme performs well in terms of energy, delay, delivery ratio and mobility

A theory for the design of deadlock-free adaptive routing algorithms for wormhole networks, proposed by the author (1991, 1993), supplies sufficient conditions for an adaptive routing algorithm to be deadlock-free, even when there are cyclic dependencies between channels. Also, two design methodologies were proposed. Multicast communication refers to the delivery of the same message from one source node to an arbitrary number of destination nodes. A tree-like routing scheme is not suitable for hardware-supported multicast in wormhole networks because it produces many headers for each message, drastically increasing the probability of a message being blocked. A path-based multicast routing model was proposed by Lin and Ni (1991) for multicomputers with 2D-mesh and hypercube topologies. In this model, messages are not replicated at intermediate nodes. This paper develops the theoretical background for the design of deadlock-free adaptive multicast routing algorithms. This theory is valid for wormhole networks using the path-based routing model. It is also valid when messages with a single destination and multiple destinations are mixed together. The new channel dependencies produced by messages with several destinations are studied. Also, two theorems are proposed, developing conditions to verify that an adaptive multicast routing algorithm is deadlock-free, even when there are cyclic dependencies between channels. As an example, the multicast routing algorithms of Lin and Ni are extended, so that they can take advantage of the alternative paths offered by the network.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>