Frequent Changes In Network Topology Research Articles

SIGNAL STRENGTH AND ENERGY AWARE RELIABLE ROUTE DISCOVERY IN MANET

Frequent changes in network topology and confined battery capacity of the mobile devices are the main challenges for routing in ad-hoc networks. In this paper, we propose a novel, Signal strength and Energy Aware routing protocol (SEA-DSR), which directly incorporates signal strength and residual battery capacity of nodes into route selection through cross layer approach. This model defines a metric called Reliability Factor for route selection among the feasible routes. It is simulated using ns2, under different mobility conditions. The simulation results shows better performance in terms of packet delivery ratio, control overhead and average end-end delay. The proposed model has extended the time to network partition and reduce the path breakages when compared with similar routing protocols DSR and SSA.

An Adaptive Secure Fuzzy Multicast communication in Large Scale Mobile Ad Hoc Networks

Multicast protocols in MANETs must consider control overhead for maintenance, energy efficiency of nodes and routing trees managements to frequent changes of network topology. Now-a-days Multicast protocols extended with Cluster based approach. Cluster based multicast tree formation is still research issues. The tree reconstruction of cluster-based multicast routing protocol will take place if any link of the trees has malfunction or the nodes move out of the link, therefore, its robust performance is unsatisfactory. The mobility of nodes will always increase the communication delay because of re-clustering and cluster head selections. In our previous proposal, reported on simulation-based experiments evaluating two different approaches clustering to multicast communication in mobile ad hoc networks (MANETs), namely AFMR and CBRP. One of the chief contributions of this work is our objective analysis of these two multicast routing protocol categories in order to characterize their behavior under a wide range of MANET mobility. In this paper, we evaluate mainly security level based in AFMR, named SAFMR and compare it with Cluster-based On Demand Multicast Routing Protocol (CODMRP) and Cluster-based routing protocol (CBRP).

Continuous Location Dependent Queries in Mobile Wireless Sensor Networks

Query processing in mobile Wireless Sensor Networks (WSNs) is still a challenging problem because sensor mobility causes frequent changes of network topology. In this paper, we study the problem of processing Continuous Location Dependent Query (CLDQ) that retrieves the sampling data of the sensors within a specific area (i.e. query area) around a mobile sensor. Existing query processing approaches can not efficiently process CLDQs with continuously moving query areas. We propose scalable techniques to process CLDQs efficiently and accurately, including a dissemination approach, a Contention-based Distance-aware Message Scheduling scheme, in which each stationary sensor's data transmissions are smartly scheduled according to its distance to the mobile sensor, and an optimization scheme for continuous processing of CLDQs. Extensive experiments indicate that our techniques demonstrate better efficiency of processing CLDQs over state-of-the-art techniques while achieving high accuracy and short query latency under various network settings.

An Assessment of Frequently Adopted Unsecure Patterns in Mobile Ad hoc Network: Requirement and Security Management Perspective

A mobile Ad hoc network (MANET) has played an imperative role in making very fast connection of mobile devices without including any centralize equipment. It is the simplest way to transfer files between two or more devices that can also act as routers. Now a day, the appropriate uses of this modern wireless communication are in emergency rescue situation, military scenarios, sensor networks, conferences and many others. Mobile Ad hoc Networks are adopted when wired networks are malfunctioning or broken down due to some unavoidable situation. This rapidly deployed network collaborates without using any preexisting fixed network infrastructure. Due to rapid deployment of mobile nodes or frequent change in network topology, security is the most important concern in Mobile Ad hoc Network. Due to its limited physical security, energy constrained operations and lack of centralized administration, Ad hoc Networks are more vulnerable to attacks than a wired networks or traditional networks. With the proliferation of cheaper, small, and more powerful mobile devices, mobile ad hoc networks (MANETs) have become one of the fastest growing areas of research. In this paper we are attempting to analyze the security attacks in Ad-hoc environment and focusing on various areas of security requirement, different types of active and passive attacks in Ad-hoc networks.

Varying Overhead Ad Hoc on Demand Vector Routing in Highly Mobile Ad Hoc Network

Problem statement: An inherent feature of mobile ad hoc networks is the frequent change of network topology leading to stability and reliability problems of the network. Highly dynamic and dense network have to maintain acceptable level of service to data packets and limit the network control overheads. This capability is closely related as how quickly the network protocol control overhead is managed as a function of increased link changes. Dynamically limiting the routing control overheads based on the network topology improves the throughput of the network. Approach: In this study we propose Varying Overhead - Ad hoc on Demand Vector routing protocol (VO-AODV) for highly dynamic mobile Ad hoc network. The VO-AODV routing protocol proposed dynamically modifies the active route time based on the network topology. Results and Conclusion: Simulation results prove that the proposed model decreases the control overheads without decreasing the QOS of the network.

Mobility impact in IEEE 802.11p infrastructureless vehicular networks

Vehicular ad hoc networks (VANETs) are an extreme case of mobile ad hoc networks (MANETs). High speed and frequent network topology changes are the main characteristics of vehicular networks. These characteristics lead to special issues and challenges in the network design, especially at the medium access control (MAC) layer. In this paper, we provide a comprehensive evaluation of mobility impact on the IEEE 802.11p MAC performance. The study evaluates basic performance metrics such as packet delivery ratio, throughput, and delay. An unfairness problem due to the relative speed is identified for both broadcast and unicast scenarios. We propose two dynamic contention window mechanisms to alleviate network performance degradation due to high mobility. The first scheme provides dynamic level of service priority via adaptation to the number of neighboring nodes, while the second scheme provides service priority based on node relative speed. Extensive simulation results demonstrate a significant impact of mobility on the IEEE 802.11p MAC performance, the unfairness problem in the vehicle-to-vehicle (V2V) communications, and the effectiveness of the proposed MAC schemes.

A Peer-Tree Based Location Lookup Service in Mobile Wireless Networks

We present a location look-up service for aiding location-based routing in wireless networks with mobile hosts. This location look up service is constructed based on a peer-tree indexing structure which represents the friendship relations among mobile hosts. The friendship is derived from the relations of sharing various-length common suffixes of host identifiers. A friendship relation determines the cooperation relation among mobile hosts. The Peer-Tree indexing structure provides a guideline for propagating location updates and queries in an organized manner. Each host periodically propagates its up-to-date location to a small number of its friends. Location queries are forwarded to and serviced at one of the hosts which hold a copy of the location under query. Paths for forwarding location updates or queries are jointly determined by the Peer-Tree indexing structure and the temporary connectivity in a network. The goals of this location look-up service include achieving a high success rate on location discovery, having low demands on network resources, and being robust to frequent changes of network topology.

Distributed Reinforcement Learning Approach for Vehicular Ad Hoc Networks

In Vehicular Ad hoc Networks (VANETs), general purpose ad hoc routing protocols such as AODV cannot work efficiently due to the frequent changes in network topology caused by vehicle movement. This paper proposes a VANET routing protocol QLAODV (Q-Learning AODV) which suits unicast applications in high mobility scenarios. QLAODV is a distributed reinforcement learning routing protocol, which uses a Q-Learning algorithm to infer network state information and uses unicast control packets to check the path availability in a real time manner in order to allow Q-Learning to work efficiently in a highly dynamic network environment. QLAODV is favored by its dynamic route change mechanism, which makes it capable of reacting quickly to network topology changes. We present an analysis of the performance of QLAODV by simulation using different mobility models. The simulation results show that QLAODV can efficiently handle unicast applications in VANETs.

Adaptive local searching and caching strategies for on-demand routing protocols in ad hoc networks

On-demand routing protocols are widely used in mobile ad hoc networks due to their capability of adjusting to frequent network topology changes within acceptable routing overhead. In this paper, we reinvestigate two techniques, route caching and searching localisation, in particular their joint effect on reducing routing overhead. We first analyse and present the optimal value for two essential parameters: route caching validation probability and local searching radius. We then propose a new routing strategy that adapts to the current caching availability and is self-tunable towards the optimal performance. Simulation shows that routing overhead is thus greatly reduced.

Scalable Multi-Layer GMPLS Networks Based on Hierarchical Cloud-Routers

This paper proposes the hierarchical cloud-router network (HCRN) to overcome the scalability limit in a multi-layer generalized multi-protocol label switching (GMPLS) network. We define a group of nodes as a virtual node, called the cloud-router (CR). A CR consists of several nodes or lower-level CRs. A CR is modeled as a multiple switching capability (SC) node when it includes more than one kind of SC, which is fiber SC, lambda SC, time-division multiplexing (TDM) SC, packet SC, even if there are no actual multiple switching capability nodes in the CR. The CR advertises its abstracted CR internal structure, which is abstracted link state information inside the CR. A large-scale, multi-layer network can then achieve scalability by advertising the CR internal structure throughout the whole network. In this scheme, the ends of a link connecting two CRs are defined as interfaces of the CRs. We adopt the CR internal cost scheme between CR interfaces to abstract the network. This CR internal cost is advertised outside the CR via the interfaces. Our performance evaluation has shown that HCRN can handle a larger number of nodes than a normal GMPLS network. It can also bear more frequent network topology changes than a normal GMPLS network.

애드혹 네트워크에서 ZRP를 기반으로 하는 경로 탐색 기법

애드혹 네트워크는 고정된 기반 구조 없이 이동 호스트들로만 구성된 네트워크이다. 이러한 네트워크는 노드의 이동으로 인한 토폴로지의 잦은 변화로 관리면에서 많은 어려움이 있다. 따라서, 애드혹 네트워크의 라우팅 경로(Routing Path)에 대한 신뢰도를 높이는 것이 점점 중요해 지고 있다. 본 논문에서는 기존의 ZRP(Zone Routing Protocol)를 기반으로 하여 라우팅 경로의 전체적인 홉(hop) 수를 줄이고, 경로상의 노드들끼리의 인증을 통하여 라우팅 경로의 신뢰성을 향상시키는 경로 탐색 방안을 제안하였다. 또한 토폴로지의 잦은 변화로 인한 라우팅 경로 유지의 어려움을 질의 제어 메커니즘을 통하여 해결하고자 시도하였다. 본 논문의 방안은 시뮬레이션을 통하여 그 효율성을 입증할 수 있었다. Ad hoc networks are groups of mobile hosts without any fixed infrastructure. Frequent changes in network topology owing to node mobility make these networks very difficult to manage. Therefore, enhancing the reliability of routing paths in ad hoc networks gets more important. In this paper, we propose a ZRP(Zone Routing Protocol)-based route discovery scheme that can not only reduce the total hops of routing path, but Improve security through authentications between two nodes. And to solve the problem in maintenance of routing paths owing to frequent changes of the network topology, we adopt a query control mechanism. The effectiveness of our scheme is shown by simulation methods.

Efficient routing in PAN and sensor networks

Routing in both PANs and sensor networks can be significantly improved, if each node knows the network topology. However, this leads to high signalling overhead and power loss, given the frequent network topology changes. In order to compromise between efficient routing and communications /power limitations, various algorithms have been proposed. In this paper, a selection of algorithms proposed for ad-hoc networks are classified according to their relevancy and efficiency, when applied to PANs and sensor networks.