Unpredictable Topology Changes Research Articles

Distributed Detour Routing Scheme for Link Failure with Minimized Overhead in LEO Satellite Networks

The mobility of low Earth orbit (LEO) satellites causes the LEO satellite network to experience topology changes. Topology change includes periodic topology change that occurs naturally and unpredictable topology change that occurs due to instability of the inter-satellite link between satellites. Periodic and unpredictable topology change causes frequent topology change, requiring massive communications throughout the network due to frequent route convergence. LEO satellites have limited onboard power because they operate on batteries. The waste of limited satellite onboard resources shortens the lifespan of the satellite, and achieving stable end-to-end transmission is challenging for the network. In this regard, minimizing communication overhead is a fundamental consideration when designing a routing scheme. In this paper, we propose a distributed detour routing scheme with minimal communication overhead. This routing scheme consists of a rapid detour, selective flooding, and link recovery procedures. When a link failure occurs in the network, a rapid detour can detect link failure using only a precalculated routing table. Subsequently, selective flooding searches for the optimal detour point within the minimum hop region and flood to detour point. After link recovery, a procedure is defined to traverse the pre-detour path and switch it back to the original path. The simulation results show that the proposed routing scheme achieves a reduction of communication overhead by 97.6% compared with the n-hop flooding approach.

A Novel Intrusion Detection System for Detecting Black-Hole Nodes in MANETS

Mobile ad-hoc networks (MANETs) are autonomous,infrastructure less, self-organized networks. In MANETs, nodes are not stationary and thus move arbitrarily, resulting in rapid and unpredictable topology changes in the network. Due to the limited transmission range of the nodes in the MANETs, these nodes are not capable of directly communicating with each other. Hence, routing paths in MANETs potentially contain multiple hops, and every node in it has the responsibility to act as a router.So, the presence of any intermediate node in the route, which is either highly congested or behaving as a malicious node, is likely to drop the packets. In computer networking, this type of attack is known as a packet drop attack or black hole attack which is a type of denial-of-service attack in which a router that is supposed to relay packets instead discards them. The proposed algorithm will detect black hole nodes in the network by implementing changes into the existing AODV routing algorithm. The implementation of the algorithm was being achieved using theNS-2 simulator.

An Interference Aware Heuristic Routing Protocol for Wireless Home Automation Networks

Wireless Home Automation Networks consist of battery powered sensors and actuators that communicate with each other over wireless channels. The sensor nodes collect environmental information such as temperature, light intensity, humidity, and pressure to provide context-aware services and to facilitate smart home control. However, resource limitations, unpredictable topology changes, and interference introduce a number of challenges to the design of home automation protocols. One of the challenging tasks is developing energy efficient routing protocols to prolong the network lifetime. This paper proposes an interference aware heuristic routing protocol which determines the forwarding path between sensors and the base station using a heuristic function and a heuristic search algorithm. On the basis of local and global distance, longevity factor (LF), and link quality (LQ), the heuristic function generates a heuristic value for each node and this value is used in A_ search algorithm to determine the efficient route. Simulation results show that the proposed routing scheme outperforms GAHR and AODVjr protocols in terms of network lifetime, energy consumption, and message throughput. Furthermore, it achieves up to 15% increase in packet delivery ratio over GAHR protocol in a noisy environment

A Location Routing Protocol based on Smart Antennas for Wireless Sensor Networks

The task of finding and maintaining routes in a Wireless Sensor Networks is a nontrivial task since energy restrictions and sudden changes in node status (e.g. failure) cause frequent and unpredictable topological changes. This work introduces a novel location routing protocol that uses smart antennas to estimate nodes positions into the network and to deliver information basing routing decisions on neighbor’s status connection and relative position, named LBRA. The main purpose of LBRA is to eliminate network control overhead as much as possible. To achieve this goal, the algorithm employs local position for route decision, implements a novel mechanism to collect the location information and involves only route participants in the synchronization of location information. In addition, the protocol uses node battery information to make power aware routing decisions. In order to asses LBRA a series of simulations were designed with the help of the Network Simulator 2 (ns2). The experiment results showed that LBRA succeed in reducing the control overhead and the routing load, improving the packet delivery rate. Additionally, network power depletion is more balanced, since routing decisions are made depending on nodes’ battery level.

Fuzzy based Load and Energy Aware Multipath Routing for Mobile Ad Hoc Networks

outing is a challenging task in Mobile Ad hoc Networks (MANET) due to their dynamic topology and lack of central administration. As a consequence of un-predictable topology changes of such networks, routing protocols employed need to accurately capture the delay, load, available bandwidth and residual node energy at various locations of the network for effective energy and load balancing. This paper presents a fuzzy logic based scheme that ensures delay, load and energy aware routing to avoid congestion and minimise end-to-end delay in MANETs. In the proposed approach, forwarding delay, average load, available bandwidth and residual battery energy at a mobile node are given as inputs to a fuzzy inference engine to determine the traffic distribution possibility from that node based on the given fuzzy rules. Based on the output from the fuzzy system, traffic is distributed over fail-safe multiple routes to reduce the load at a congested node. Through simulation results, we show that our approach reduces end-to-end delay, packet drop and average energy consumption and increases packet delivery ratio for constant bit rate (CBR) traffic when compared with the popular Ad hoc On-demand Multipath Distance Vector (AOMDV) routing protocol.

Simulation of AODV under Multiple Blackhole and Grayhole Attack in MANETS

networks are infrastructure-less network designed for communication without aid of any centralised administration. An Adhoc network generally consists of fixed nodes. Another variation of Adhoc network is MANETs. MANETs consists of mobile nodes rather than fixed nodes. MANETs is self- configuring network of mobile nodes that can be formed anytime and anywhere. Due to dynamic nature of wireless medium, unpredictable topological changes, mobility and limited resource constraints, at network layer MANETs routing protocols poses various security challenges. AODV routing protocol is most popular protocol because of its low routing overhead and less algorithmic complexity. But it is vulnerable to various attacks because of lack of security system design, Blackhole and Grayhole attack being one of them. This paper evaluates performance of AODV under multiple Blackhole and Grayhole attacks.

Congestion avoidance routing for MANETs

In a mobile ad hoc network MANET, communication connections need to adapt to frequent and unpredictable topology changes. Early solutions focused reconnecting a broken link quickly with a low overhead; however, this strategy cannot cope with a high mobility environment. For high mobility environments, greedy techniques rely on any mobile hosts along the general direction of the destination node to forward data packets. However, the greedy approach suffers from packet loss because the packet forwarding policy does not consider traffic congestion along the route or the direction. In this paper, we propose a congestion avoidance routing CAR technique for two greedy protocols, connectionless approach CLA and contention-based forwarding CBF, to address the packet loss problem by rerouting packets dynamically to avoid traffic congestion. To demonstrate the improvement, we present extensive simulation results to show the proposed techniques can prevent the occurrence of contention areas and significantly outperform existing techniques.

A novel hierarchical model for vehicular traffic regulation

The aim of the research is to regulate the vehicular traffic in the most effective and efficient way in Vehicular Adhoc Networks (VANET). The challenges faced by the existing networks are ripple effect of reclustering, communication complexity, mobility, throughput and delay in an urban environment. Moreover unpredictable topology changes in VANET, obstruct expected packet delivery ratio and leads to congestion by overheads for link maintenance. The existing routing techniques suffer from excessive loss of data, delay and need for continuous monitoring where group member's loss their link in randomwaypoint mobility scenarios. In this paper, a novel hierarchical model combining the features of hierarchical clustering, hybrid mobility model and location based 2hop Multicast Flooding (L2MF) for data forwarding has been proposed. By comparing the proposed protocol with previous protocols, the enhanced performance in packet delivery ratio, control overhead, and end-to-end delay has been proved.

A consensus-based ℓ- Exclusion algorithm for mobile ad hoc networks

This paper addresses the ℓ -Exclusion problem for mobile ad hoc networks. The ℓ -Exclusion problem, a generalization of distributed mutual exclusion problem, involves a group of processes, each of which intermittently requires access to one of ℓ identical resources or pieces of code called the critical section (CS). This paper presents a consensus-based mobility-aware ℓ- Exclusion (LE) algorithm that operates asynchronously and copes explicitly with arbitrary (possibly concurrent) topology changes associated with such networks. The algorithm can tolerate link changes or failures, sudden crashes or recoveries of at most ℓ − 1 mobile nodes. The algorithm is based on collection of enough consensuses for a mobile node intending to enter CS, and uses diffusing computations for this purpose. This paper presents a simulation to demonstrate that the proposed algorithm, as compared to the k-Reverse Link (KRL) algorithm, is quite effective to variety of operating conditions, and is highly adaptive to frequent and unpredictable topology changes due to link changes or failures.

Epidemic-based reliable and adaptive multicast for mobile ad hoc networks

An emerging approach to distributed systems exploits the self-organization, autonomy and robustness of biological epidemics. In this article, we propose a novel bio-inspired protocol: EraMobile (Epidemic-based Reliable and Adaptive Multicast for Mobile ad hoc networks). We also present extensive performance analysis results for it. EraMobile supports group applications that require high reliability. The protocol aims to deliver multicast data reliably with minimal network overhead, even under adverse network conditions. With an epidemic-based multicast method, it copes with dynamic and unpredictable topology changes due to mobility. Our epidemic mechanism does not require maintaining any tree- or mesh-like structure for multicasting. It requires neither a global nor a partial view of the network, nor does it require information about neighboring nodes and group members. In addition, it substantially lowers overhead by eliminating redundant data transmissions. Another distinguishing feature is its ability to adapt to varying node densities. This lets it deliver data reliably in both sparse networks (where network connectivity is prone to interruptions) and dense networks (where congestion is likely). We describe the working principles of the protocol and study its performance through comparative and extensive simulations in the ns-2 network simulator.

Connectionless protocol: a localised approach to wireless ad hoc networks

Most mobile ad hoc network's communication techniques need to discover routes and establish a connection before they can communicate. This strategy cannot robustly adapt to frequent unpredictable topology changes due to high mobility. Constant reconnections incur significant overhead making these schemes unsuitable for applications such as voice and video. To address these issues, we explore a connectionless paradigm in this paper. By leverage GPS technology, data packets are relayed along the general direction to packets' destination using different intermediate nodes at different times without having to first establish a connection. The performance of this solution is essentially unaffected by node mobility.

Effectiveness of Reliable Routing Protocols in Mobile Ad Hoc Networks

Due to unpredictable topology change and frequent link failure, it becomes evident major challenge to provide the stable route between source and destination in mobile ad hoc networks. Unlike previous multipath routing schemes for redundancy and unicast routing protocol utilizing the longest route expiration time measured by geographical information supported by Global Positioning System (GPS), we develop a framework to establish the most stable route based on measured frequency of link failure, available battery as well as the number of actual connections. To evaluate performance of proposed scheme, we provide practical simulation results for multipath and unicast routing protocol in terms of packet delivery ratio, control overhead, average hop length as well as end-to-end delay. Through analysis of simulation results, we demonstrate that our scheme shows better performance than general unicast routing protocol as well as similar packet delivery ratio to multipath routing protocol with less maintenance overhead.

Epidemic-based approaches for reliable multicast in mobile ad hoc networks

We present a classification of epidemic-based approaches utilized in the context of mobile ad hoc networks (MANET) with a focus on reliable multicast protocols. We provide a brief description of the other approaches to reliable multicasting in MANETs as well. Then, we describe our protocol, namely EraMobile, offering Epidemic-based Reliable and Adaptive Multicast for Mobile ad hoc networks. EraMobile's target is group applications requiring high-level of reliability and the protocol aims to provide fully reliable multicast data delivery with minimal network overhead even in the adverse network conditions. EraMobile utilizes an epidemic-based method in multicast operation to cope with dynamic and unpredictable topology changes arising from the mobility. Our epidemic mechanism does not require the maintenance of any tree- or mesh-like structure for multicasting. It also needs neither having global or partial view of the network nor having information of neighboring nodes and group members. Besides, it substantially minimizes the overhead incurred by eliminating redundant data transmissions. Another distinguishing feature of EraMobile is its capability of adapting to varying node densities in order to provide reliable data delivery in both sparse networks, where the network connectivity is prone to interruptions, and dense networks, where congestion is likely to occur. EraMobile is shown to achieve fully reliable multicast data delivery studied through extensive simulations by outperforming the other protocols compared, especially in terms of both packet delivery ratio and overhead efficiency.

모바일 애드혹 네트워크를 위한 링 기반 멀티캐스트 라우팅 구조

예상치 못한 에드혹 망의 접속형태의 변경이 동반되는 멀티캐스트 라우팅 프로토콜에 대한 연구에 많은 과제를 남겨놓고 있으며, 다양한 이동 에드혹 망에 적합한 프로토콜에 대한 연구의 필요성이 제기되고 있다. 본 논문에서는 계층적 Eulerian 링 멀티캐스트 구조를 갖는 새로운 프로토콜을 제안한다. 제안한 구조는 Eulerian 링, 계층구조, 멀티캐스트 에이전트를 갖으며 기존의 방법보다 효율적이며 안전한 특성을 갖는다. 제안한 구조는 트리기반 및 메시기만 멀티캐스트 프로토콜과 비교하여 제어트래픽의 양, 점대점 지연, 패킷전송률 등에 있어 우수함은 시뮬레이션을 통해 입증한다. Due to the frequent and unpredictable topology changes, multicast still remains as challenge and no one-size-fits-all protocol could serve all kinds of needs in mobile ad hoc network. In this paper, we propose a novel scheme of Hierarchical Eulerian Ring Oriented Multicast Architecture (HEROMA) over mobile ad hoc network. It has features that concentrate on efficiency and robustness simultaneously. It is also an application-driven proposal for hazard detection. Architectures including Eulerian ring, hierarchy and multicast agent are investigated in detail Simulation results different level of improvements on control traffic, end-to-end delay and packet delivery ratio by comparing with tree-based and mesh-based multicast protocols.

Pilot: probabilistic lightweight group communication system for ad hoc networks

Providing reliable group communication is an ever recurring topic in distributed settings. In mobile ad hoc networks, this problem is even more significant since all nodes act as peers, while it becomes more challenging due to highly dynamic and unpredictable topology changes. In order to overcome these difficulties, we deviate from the conventional point of view, i.e., we fight fire with fire, by exploiting the nondeterministic nature of ad hoc networks. Inspired by the principles of gossip mechanisms and probabilistic quorum systems, we present in this paper PILOT (probabilistic lightweight group communication system) for ad hoc networks, a two-layer system consisting of a set of protocols for reliable multicasting and data sharing in mobile ad hoc networks. The performance of PILOT is predictable and controllable in terms of both reliability (fault tolerance) and efficiency (overhead). We present an analysis of PILOT's performance, which is used to fine-tune protocol parameters to obtain the desired trade off between reliability and efficiency. We confirm the predictability and tunability of PILOT through simulations with ns-2.

Multipath Routing with Self-Healing Technique for Quality of Service (QoS) Support in Mobile Ad hoc Networks (MANET)

Mobile ad hoc network is an autonomous system of mobile hosts/routers connected by wireless links. The routers / hosts are free to move randomly and organize themselves arbitrarily, resulting in rapid and unpredictable topology changes. The QoS routing for mobile ad hoc networks has challenging problems due to dynamic topology and limited bandwidth. To combat these inherent unreliabilities, we propose a multipath routing algorithm with self healing property. The performance of the algorithm was studied using the public domain simulator GloMoSim and it was found that the algorithm gives good throughput, and less routing overhead ratio. It also supports load balancing and possesses good resilience property.

Wireless ad hoc multicast routing with mobility prediction

An ad hoc wireless network is an infrastructureless network composed of mobile hosts. The primary concerns in ad hoc networks are bandwidth limitations and unpredictable topology changes. Thus, eff...