A 3.4713-approximation algorithm for the capacitated multicast tree routing problem

In WDM networks with limited drop-offs, the route of a multicast connection consists of a set of light-trees. Each of the light-tree is rooted at the source node and contains no more than a limited number, say k, destination nodes due to the power loss of dropping optical signals off at destination nodes. We call such a light-tree k-drop light-tree. In this paper we study the multicast routing problem of constructing a set of k-drop light-trees that have the minimal network cost. The network cost of a set of light-trees is defined as the summation of the link cost of all the light-trees. We first prove that this problem is polynomial-time solvable for k=2 and NP-hard for k/spl ges/3. We then propose a 4-approximation algorithm for the problem for k /spl ges/3. A wavelength assignment algorithm is also proposed to assign wavelengths to the light-trees of a multicast connection. In the end we give simulation results showing that k-drop multitree muting can significantly save not only the network cost but also wavelengths used. Moreover, when k/spl ges/5 its performance is very close to the case where k is infinite (i.e., the case of using a single tree for a multicast connection).

Nongeostationary orbit (NGSO) satellite-based Internet is an important part of the future network. One single NGSO satellite has the characteristics of high-speed movement, small coverage area, and short connection time; therefore, the method of multisatellite collaboration is adopted in NGSO satellite-based Internet. Caching is an effective technique to reduce the transmission load and delay, especially for high-value content. However, the traditional caching cannot be applied to the NGSO satellite network directly due to the frequent switching of service satellites. As a result, some high-valued cached data need to be transmitted among satellites, such that an effective routing between the source and destination node needs to be established orderly in the satellite network. This paper proposes a dynamic routing strategy based on multilayer satellite architecture for unicast and multicast scenarios, respectively. For the unicast, a routing strategy based on Q -learning is proposed to optimize bandwidth and delay simultaneously, and the effectiveness is verified by the comparison against the traditional routing strategy. For the multicast, an advanced Q -learning multicast routing algorithm based on spatial directionality is proposed to optimize the overall transmission success rate and resource cost, and the superiority of the proposed routing strategy is verified by simulation results.

Decentralized learning of randomization-based neural networks with centralized equivalence

A mobile ad hoc network (MANET) is a dynamically reconfigurable wireless network that does not have a fixed infrastructure. Due to the high mobility of nodes, the network topology of MANETs changes very fast, making it more difficult to find the routes that message packets use. Because mobile nodes have limited battery power, it is therefore very important to use energy in a MANET efficiently. In this paper, we propose a power-aware multicast routing protocol (PMRP) with mobility prediction for MANETs. In order to select a subset of paths that provide increased stability and reliability of routes, in routing discovery, each node receives the RREQ packet and uses the power-aware metric to get in advance the power consumption of transmitted data packets. If the node has enough remaining power to transmit data packets, it uses the global positioning system (GPS) to get the location information (i.e., position, velocity and direction) of the mobile nodes and utilizes this information to calculate the link expiration time (LET) between two connected mobile nodes. During route discovery, each destination node selects the routing path with the smallest LET and uses this smallest link expiration time as the route expiration time (RET). Each destination node collects several feasible routes and then selects the path with the longest RET value as the primary routing path. Then the source node uses these routes between the source node and each destination node to create a multicast tree. In the multicast tree, the source node will be the root node and the destination nodes will be the leaf nodes. Simulation results show that the proposed PMRP outperforms MAODV (Royer, E. M. & Perkins, C. E. (1999). In Proceedings of the ACM MOBICOM, pp. 207---218, August 1999.) and RMAODV (Baolin, S. & Layuan, L. (2005). In Proceeding of the 2005 IEEE International symposium on microwave antenna, propagation and EMC technologies for wireless communications, Vol. 2, pp. 1514---1517, August 2005.).

In this paper, we study the multicast routing problem in ATM networks. The multicast routing problem, also known as the Steiner tree problem, has been well studied in the literature. However, less attention has been made for the definition of link costs and evaluating the performance of multicast routing algorithm from the network revenue point of view. Therefore, in this paper, we first proposed two approaches, namely, the Markov decision process-based (MDP) and maximum free residual capacity-based (MFC) approaches for defining link costs. We then developed three heuristic algorithms for finding near optimal multicast trees. Our simulation results indicate algorithms that estimating link costs based on the MDP approach yield better performance than those that based on the MFC approach. Among the three multicast routing algorithms that use MDP approach for estimating link costs, the algorithm that treats a multicast call as a collection of multiple point-to-point calls yields the worst performance while the algorithm that based on the genetic algorithm yields the best performance.

In mobile ad hoc networks, routing schemes using location information have been proposed. Most of these schemes assume that the source node already knows the location information of the destination node. However, since all nodes are always moving, it is difficult to apply this assumption to the real mobile ad hoc environment. In order to cope this difficulty, this paper presents a new routing scheme HRLI, a Hybrid Routing with Location Information, which using the threshold for the communication range of all nodes. And it considers the location and velocity information of the destination node and the neighboring nodes. In HRLI, when a source node creates a route to a destination node, the future location of the destination node predicted by the source node is calculated using these location and velocity information. And the source node sends data packets based on the predicted location information of destination node and neighboring nodes. This paper shows that HRLI achieves high data delivery ratio and fewer overheads for using the threshold of communication range and the predicted location through simulation experiments

Mobile ad hoc network (MANET) is a group of mobile nodes that communicates with each other without any supporting infrastructure. These networks have some unique features such as dynamic mobility, open nature, lack of infrastructure, limited physical security and they are vulnerable to several security threats. Malicious node can drop all or partial received packets instead of forwarding them to the next hop through the path. In order to find the malicious nodes, an initial transmission is made between the source and destination nodes. Using fuzzy rules, the trust value of each node is computed and it varies from 0 to 1. A common threshold value is set for each node and by using this threshold value, every node in the network can be identified as either a malicious node or a regular node. After identifying the malicious nodes, these nodes are eliminated by muting the power to off state. As the malicious nodes are eliminated between source and destination nodes, source node can select another trusted path to its destination
 node. For security and authentication of routing information, hybrid cryptography is employed, using advanced encryption standard (AES) and elliptic curve cryptography (ECC) algorithms. AES algorithm is used as symmetric algorithm to encrypt the routing information and ECC algorithm is used as asymmetric algorithm to encrypt the public key. During encryption, the original plain text is converted into cipher text with encrypted public key and similarly during decryption cipher text is converted into original plain text with decrypted private keys. So the proposed method involves both AES and ECC algorithms which provides security mechanism as efficient and sufficient one. The experimental simulations are carried for the proposed model using network simulator 2 (NS-2) for Throughput, Delay, Packet delivery ratio, Packet overhead and Packet drop.

Reliable communication in cube-based multicomputers using the safety vector concept is studied in this paper. In our approach, each node in a cube-based multicomputer of dimension n is associated with a safety vector of n bits, which is an approximated measure of the number and distribution of faults in the neighborhood. The safety vector of each node can be easily calculated through n-1 rounds of information exchange among neighboring nodes. Optimal unicasting between two nodes is guaranteed if the kth bit of the safety vector of the source node is one, where k is the Hamming distance between the source and destination nodes. The concept of dynamic adaptivity is introduced, representing the ability of a routing algorithm to dynamically adjust its routing adaptivity based on fault distribution in the neighborhood. The feasibility of the proposed unicasting can be easily determined at the source node by comparing its safety vector with the Hamming distance between the source and destination nodes. The proposed unicasting can also be used in disconnected hypercubes, where nodes in a hypercube are disjointed (into two or more parts). We then extend the safety vector concept to general cube-based multicomputers.

As the performance of mobile nodes advances, the ad hoc network will work with many mobile nodes. In such network, the route between the source node and the destination node is elongated, and then the route maintenance might become more difficult due to the topology change. Therefore, we have proposed Route-Split Routing (RSR) scheme for large mobile ad hoc network environments. RSR sets up multiple Subroute Management Nodes (SMNs) on the route between the source node and the destination node and divides the route into multiple subroutes. Since the subroute between two adjacent SMNs is locally managed, RSR has less overhead for the route maintenance and achieves the higher performance than AODV. In addition, RSR becomes tolerant to the multiple concurrent link failure because the route is repaired by each SMN on a subroute basis. RSR could provide higher data packet delivery ratio, but has high overhead because the route becomes longer as the subroute can be locally repaired and separately. Therefore, this paper proposes three mechanisms to enhance the performance of RSR for large mobile ad hoc network environment and then evaluates it through simulation environment. As a result, the enhanced RSR with three proposed mechanism can decrease the total control overhead by 50 percent with high data packet delivery ratio.Keywordsmobile ad hoc networksad hoc on-demand distance vector routing

In a communication network with a source node, a multicast tree is defined as a tree rooted at the source node and all its leaves being recipients of the multicast originating at the source. The tree or bandwidth cost is normally measured by its utilization of tree links along with the quality of service (QoS) measures such as delay constraint and end-to-end delay. However, if nodes are allowed to join or leave the multicast group at any time during the lifetime of the multicast connection, then the problem is known as dynamic multicast routing problem. In this article, we combine a greedy approach with static multicast routing using Tabu Search to find a low-cost dynamic multicast tree with desirable QoS parameters. The proposed algorithm is then compared with several static multicast routing algorithms. The simulation results show that, on a large number of events, i.e., where nodes are leaving or joining, the proposed algorithm is able to find multicast trees of lower cost and more desirable QoS properties.

The advancement of network induces great demands on a series of applications such as the multicast routing. This paper firstly makes a brief review on the algorithms in solving routing problems. Then it proposes a novel algorithm called the distance complete ant colony system (DCACS), which is aimed at solving the multicast routing problem by utilizing the ants to search for the best routes to send data packets from a source node to a group of destinations. The algorithm bases on the framework of the ant colony system (ACS) and adopts the Prim's algorithm to probabilistically construct a tree. Both the pheromone and heuristics influence the selection of the nodes. The destination nodes in the multicast network are given priority in the selection by the heuristics and a proper reinforcement proportion to the destination nodes is studied in the case experiments. Three types of heuristics are tested, and the results show that a modest heuristic reinforcement to the destination nodes can accelerate the convergence of the algorithm and achieve better results.

Recently, importance of wireless networks increased significantly. Wireless Mesh Networks (WMNs) are receiving growing attention and offer many advantages in terms of connectivity and reliability. Multicast communication is an important technology for wireless networks in which the same content of data should be delivered to a group of receiver nodes simultaneously. So multicast routing provides efficient data distribution among a group of nodes rather than other traditional unicast routing strategies. Here we focus on the Channel Allocation (CA) scheme which efficiently utilizes multiple wireless interfaces to achieve better throughput and improving the radio interference. This kind of problem has been proved to be NP-hard. Hence, solving the multicast channel assignment problem in MCMR WMNs will be more complicated than that of traditional networks. The research in this paper is aimed at improving the network performance for efficient joint channel assignment and multicast routing problem in MCMR WMNs by using the Q-learning scheme. We also implement our proposed channel assignment algorithm, and evaluate and compare its performance with LAMR. Simulations and experimental results demonstrate that QLMR outperforms the previous works in terms of achieved average throughput, average end-to-end delay, average packet delivery ratio and so on. We will evaluate the performance of the proposed scheme.

This paper is going to present a hybrid model for IDS using ANN and data mining approaches. it is important to deploy a hybrid network using ANN based and data mining based IDS systems that can enable the system in making decisions on intrusion in a mobile environment. MANET is an infrastructure-less ad-hoc network. It is a collection of mobile nodes that are connected in an arbitrary and dynamic manner. ANN (Artificial Neural Network) is a type of Machine Learning scientific and statistical model that is used by computer systems in order to perform a task without involvement of explicit intrusion, rather than relying on interference and patterns instead. As there is node mobility that can impose different security issues, MANETs are found more susceptible in security provision. In order to resolve this security issue, some authentication and encryption techniques can be proposed for the first-line defensein order to mitigate the security risks. However, complete eradication of these types of risks is next to impossible. For theSecond line defense, the necessity of an Intrusion Detection System (IDS) is essential in this case. IDS can be referred as a method tool or resource that can help to detect access and warn for any activity of unapproved or unauthorized network activity. The current research has been done to prevent the network from the intruders. The number of attackers has been increased in the network because of more usage of technology and wireless network. Data is not allowed by the attackers to transmit successfully from source node to destination node. These intruders want to steal data and let to the unsuccessful transmission. In this research we are deploying 48 to 66 nodes in a defined communication area of 1000*1000 height and width. While starting the transmission source node and destination node is defined. After that while using IDS and AODV protocol route is created between destination and source node. If network decreases its performance will need to apply cuckoo search as an optimization algorithm. Cuckoo search algorithm extracts the properties and observe the energy been consumed by each node. Optimized properties provided as an input to the decision tree classifier with the help of this, system is being prepared according to their properties. If there will be a chance for existence of intruder in the network then it will be classified using decision tree algorithm. At the end QOS parameters energy consumption is performed using cuckoo search optimization algorithm. The detected intruder is prevented using decision tree and removed from the MANET network.

Multicast routing algorithms for mobile ad-hoc networks have been extensively researched in the recent past. In this paper, we present two algorithms for dealing with multicast routing problem using the notion of virtual forces. We look at the effective force exerted on a packet and determine whether a node could be considered as a Steiner node. The nodes' location information is used to generate virtual circuits corresponding to the multicast route. QoS parameters are taken into consideration in the form of virtual dampening force. The first algorithm produces relatively minimal multicast trees under the set of constraints. We improve upon the first algorithm and present a second algorithm that provides improvement in average residual energy in the network as well as effective cost per data packet transmitted. In this paper, the virtual-force technique has been applied for multicast routing for the first time in mobile ad-hoc networks.

The high-level contribution of this paper is the design and development of routing protocols to discover stable paths and trees for unicast and multicast communication based on the predicted link expiration times LETs of links in mobile ad hoc networks MANETs. Both of the stability-based unicast SILET and multicast MILET routing protocols discover routes through an on-demand request-reply cycle with a link weight being 1 plus the inverse of the LET of the link. The destination nodes and the multicast receiver nodes connect to the source node through paths that have the lowest sum of the link weights. The inclusion of a '1' in the link weight helps to minimise the hop count of the paths from the source node to each of the targeted end nodes of the communication session; the inclusion of the inverse of the LET in the path/tree optimisation function helps to maximise the path/tree lifetime. The proposed protocols effectively neutralise the stability-hop count tradeoff and are able to simultaneously maximise the path/tree lifetime and minimise the hop count per source-destination/source-receiver path. The performance of SILET and MILET has been extensively studied in the ns-2 simulator along with contemporary unicast and multicast routing protocols.