On-demand Protocol Research Articles

Fuzzy Based Load and Stability Aware Routing for Mobile Ad Hoc Networks

Mobile ad hoc networks (MANETs) are very promising wireless technology and they support wide range of applications. Due to the dynamic nature of MANETS, their routing process faces several challenges. In this paper, we propose a new, Load and Stability Aware Ad Hoc on-demand Distance Vector protocol (LSA-AODV) for efficient data transmission in MANET. It applies fuzzy logic to stability metric and traffic density of the route. The ultimate intend is to select a reliable path for data communication and to reduce the number of route breakages, collisions and contention. It also utilizes stability and traffic density metrics to control broadcasting of routing messages. This protocol is compared with other similar routing protocols: LBAR and AODV. We use ns-2 for simulation. Our simulation results show that, the proposed protocol outperforms the existing routing protocols in terms of end-to-end delay and packet delivery ratio. It also considerably reduced the routing overhead.

Challenges in Mobile Ad Hoc Network for Secure Data Transmission

An ad-hoc mobile network is a collection of mobile nodes that are dynamically and arbitrarily located in such a manner that the interconnections between nodes are capable of changing on a continual basis. The primary goal of such an ad-hoc network routing protocol is correct and efficient route establishment between a pair of nodes so that messages may be delivered in a timely manner. LAR is an on-demand protocol who is based on the DSR (Dynamic Source Routing). The Location Aided Routing protocol uses location information to reduce routing overhead of the ad-hoc network! Normally the LAR protocol uses the GPS (Global Positioning System) to get these location information’s. With the availability of GPS, the mobile hosts knows there physical location. Ad hoc networks are a new wireless networking paradigm for mobile hosts. Unlike traditional mobile wireless networks, ad hoc networks do not rely on any fixed infrastructure. Instead, hosts rely on each other to keep the network connected. The military tactical and other security-sensitive operations are still the main applications of ad hoc networks, although there is a trend to adopt ad hoc networks for commercial uses due to their unique properties. One main challenge in design of these networks is their vulnerability to security attacks. In this paper, we study the threats an ad hoc network faces and the security goals to be achieved. We identify the new challenges and opportunities posed by this new networking environment and explore new approaches to secure its communication. In particular, we take advantage of the inherent redundancy in ad hoc networks - multiple routes between nodes to defend routing against denial of service attacks.

Intratympanic gentamicin treatment ‘as needed’ for Meniere’s disease. Long-term analysis using the Kaplan–Meier method

In recent years, several titration or on-demand protocols using low-dose repeated intratympanic (IT) gentamicin injections have been adopted for the vertigo control in unilateral medical refractory Menière's disease (MD). Because of the frequent recurrence and the need to treat the patients several times, it is difficult to strictly follow the 1995 AAO-HNS criteria to classify the results. The Kaplan-Meier analysis provides an effective and simpler method to address these concerns. We report the results of a long-term study (7 years) on a large population of MD patients (174) treated with on-request low-dose delayed IT gentamicin injections analysed using the Kaplan-Meier survival method. Effective vertigo control was obtained with a single injection in 40.2% of the patients (excellent responders) and with repeated injections (2-9) in 43.7% of the patients (moderate responders). Only six patients (3.5%) needed to be submitted to vestibular neurectomy because of the persistence of vertigo attacks (non-responders). A subgroup of 22 patients (12.6%) reporting a late recurrence of vertigo attacks after an initial vertigo-free interval lasting more than 2 years (short-term responders) were successfully treated with a further cycle of injections. In no cases, we observed significant signs of cochlear or vestibular toxicity. Kaplan-Meier survival analysis provided an excellent method for reporting treatment success or failure in patients followed for variable length of time with our kind of protocol.

An On-demand Scheduling Routing Protocol for IPv6 Industrial Wireless Sensor Networks based on Deterministic Scheduling

An On-demand Scheduling Routing Protocol for IPv6 Industrial Wireless Sensor Networks based on Deterministic Scheduling

Hierarchical Range Sectoring and Bidirectional Link Quality Estimation for on-demand collections in WSNs

The paper presents two mechanisms for designing an on-demand, reliable and efficient collection protocol for Wireless Sensor Networks. The former is the Bidirectional Link Quality Estimation, which allows nodes to easily and quickly compute the quality of a link between a pair of nodes. The latter, Hierarchical Range Sectoring, organizes sensors in different sectors based on their location within the network. Based on this organization, nodes from each sector are coordinated to transmit in specific periods of time to reduce the hidden terminal problem. To evaluate these two mechanisms, a protocol called HBCP (Hierarchical-Based Collection Protocol), that implements both mechanisms, has been implemented in TinyOS 2.1, and evaluated in a testbed using TelosB motes. The results show that the HBCP protocol is able to achieve a very high reliability, especially in large networks and in scenarios with bottlenecks.

Effective Analysis of Different Parameters in Ad hoc Network for Different Protocols

A wireless Ad-hoc network consists of wireless nodes communicating without the need for a centralized administration, in which all nodes potentially contribute to the routing process. A user can move anytime in an ad hoc scenario and, as a result, such a network needs to have routing protocols which can adopt dynamically changing topology. To accomplish this, a number of ad hoc routing protocols have been proposed and implemented, which include Dynamic Source Routing (DSR), ad hoc on-demand distance vector (AODV) routing, and temporally ordered routing algorithm (TORA). In this paper, we analyze the performance differentials to compare the above-mentioned commonly used ad hoc network routing protocols. We report the simulation results of four different scenarios for wireless ad hoc networks having thirty nodes. The performances of proposed networks are evaluated in terms of number of hops per route, re transmission attempts, traffic sent, traffic received and throughput with the help of OPNET simulator. Channel speed 11Mbps and simulation time 20 minutes were taken. For this above simulation environment, TORA shows better performance over the two on-demand protocols, that is, DSR and AODV

Performance Evaluation of AODV and DSR On-Demand Routing Protocols With Varying MANET Size

A mobile ad hoc network (MANET) is a collection of wireless mobile nodes dynamically forming a network topology without the use of any existing network infrastructure or centralized administration. Routing is the process which transmitting the data packets from a source node to a given destination. The main procedure for evaluating the performance of MANETs is simulation. The on-demand protocol performs better than the table-driven protocol. Different methods and simulation environments give different results. It is not clear how these different protocols perform under different environments. One protocol may be the best in one network configuration but the worst in another. In this paper an attempt has been made to compare the performance of on demand reactive routing protocols i.e. Ad hoc On Demand Distance Vector (AODV) and Dynamic Source Routing (DSR). As per our findings the differences in the protocol mechanics lead to significant performance differentials for both of these protocols. Always the network protocols were simulated as a function of mobility, but not as a function of network density. In our paper the performance of AODV and DSR is evaluated with respect to performance metrics like Packet Delivery Fraction (PDF), Average end-to-end delay, Normalized Routing Load (NRL) and throughput by varying network size up to 50 nodes. These simulations are carried out using the NS-2 which is the main network simulator, NAM (Network Animator), AWK (post processing script). Our results presented in this research work demonstrate the concept AODV and DSR routing protocols w.r.t. MANET size in an Ad hoc environment.

DEPTH-3 ADJACENCY CLUSTER BASED ROUTING PROTOCOL

In general, existing routing protocols in adhoc networks can be classified as proactive, reactive or hybrid. Proactive protocols are table driven. Proactive protocols maintain entire topology of network. So whenever there is routing request connection is established quickly. Reactive protocols are also known as On-demand protocols. On demand protocols based on fact that there is no point in maintaining network topology since it is always changing. Hybrid protocols combines approach of both reactive and proactive. Cluster based routing protocol (CBRP) is hybrid routing protocol designed for MANET. By clustering nodes into groups, the protocol efficiently minimizes flooding, traffic during route discovery. However we have realized mobility of the nodes is not considered in route reply process of the protocol. There is no mechanism defined for mobility of cluster head in route reply process. In this paper we have studied existing routing strategies in MANET and proposed a solution to the drawback we found in CBRP. Performance of CBRP will enhanced using our proposed solution.

Choroidal thickness after intravitreal ranibizumab injections for choroidal neovascularization

PurposeTo study changes in choroidal thickness with ranibizumab treatment for choroidal neovascularization (CNV).DesignProspective case series.MethodsThis prospective study consisted of 60 CNV-affected eyes of 60 patients treated with intravitreal injections of ranibizumab using an on-demand protocol after an initial loading phase. The eyes studied included 20 with age-related macular degeneration (AMD), 20 with polypoidal choroidal vasculopathy (PCV), and 20 with myopic CNV. In the eyes with AMD and PCV, choroidal thickness at the fovea was measured with optical coherence tomography using enhanced depth imaging. In eyes with myopic CNV, the choroidal thickness was measured using standard optical coherence tomography without the enhanced depth imaging technique.ResultsWith ranibizumab treatment, central retinal thickness decreased significantly (P < 0.001) and visual acuity improved significantly (P < 0.001). However, central choroidal thickness (167.2 ± 108.3 μm) showed no significant change at 1 month after the loading phase (165.2 ± 107.8 μm, P = 0.120) or at final examination (164.8 ± 107.7 μm, P = 0.115). At baseline, central retinal thickness in eyes with AMD was significantly greater that those with PCV (P = 0.005) or high myopia (P = 0.029). However, central choroidal thickness in eyes with myopic CNV was significantly thinner than in eyes with AMD (P < 0.001) or PCV (P < 0.001). In each type of disease, there was no significant change in central choroidal thickness with ranibizumab treatment.ConclusionThe effect of ranibizumab on the choroidal thickness is minimal, if any.

Stable Route Link in on-Demand Multicast Routing Protocol for Ad Hoc Networks

Mobile ad hoc networks (MANET) are provisionally connected networks with no permanent infrastructure. A mobile ad hoc network is a self-organized and energetically reconfigurable wireless network without wired infrastructure and central administration. Nodes in the mobile ad hoc network can immediately create a communication structure while each node moves in a random way. Multicasting is capable of performing required services for ad hoc applications. The dynamic nature of the network topology and limited resources, maintaining and finding the path for multicasting data is still further challenging. Several protocols have been designed for multicasting in mobile ad hoc networks. On demand multicast routing protocol is one such protocol. ODMRP is mesh based and on-demand protocol that uses forwarding group to communicate a mesh for each multicasting group. The aim of the proposed algorithm is to find the stable path selection in ODMRP for forwarding packets. The basic on demand multicast routing protocol path selection uses minimum delay principle. The proposed algorithm considers node energy in path selection from source to destination. This article discusses the studies on output parameters such as control overhead and end to end delay by varying the input parameters viz., multicast groups size and mobility in the developed algorithm. Experimental results confirm that this approach can improve stability of path due to node energy consumption.

Dynamic Reverse Route for On-Demand Routing Protocol in MANET

successful connection between a pair of source and destination nodes. An efficient routing protocol constructs routing path with minimal time, less routing overhead and capable of utilizing all possible link connectivity. In general, most on-demand MANET routing protocols operates over symmetrical and bidirectional routing path, which is infeasible due to the inherent heterogeneous properties of wireless devices. Simulation results show that the presence of unidirectional links on a network severely affect the performance of a routing protocol. In this paper, a robust protocol independent scheme is proposed, which enable immediate rediscovery of alternative route for a path blocked by a unidirectional link. The proposed scheme is efficient; route rediscovery is locally computed, which results in significant minimization of multiple route packets flooding. Nodes may exploit route information of immediate neighbors using the local reply broadcast technique, which then redirect the control packets around the unidirectional links, therefore maintaining the end-to-end bidirectional connection. The proposed scheme along with Ad Hoc On-demand Distance Vector (AODV) and AODV-Blacklist routing protocol is investigated over three types of mobility models. Simulation results show that the proposed scheme is extremely reliable under poor network conditions and the route connectivity can be improved by as much as 75%.

SQR-AODV: A STABLE QOS-AWARE RELIABLE ON-DEMAND DISTANCE VECTOR ROUTING PROTOCOL FOR MOBILE AD HOC NETWORKS

In a mobile ad hoc network (MANET), the topology of the network may change rapidly and unexpectedly due to mobility of nodes. Thus, setting up routes that meet high reliability is a very challenging issue. Another important problem in the MANETs is the energy consumption of nodes. When the energy of a node is depleted, it stops working thus links break. Hence it is very important to find a route that has sufficient energy level and high stability, and so can obtain reliable routing and data transmission. To address the aforementioned problems, we propose a reliable QoS routing protocol which bases on the route life time that is obtained using mobility information, the residue energy and hop count. Therefore in this scheme, data is sent through a route with high stability, high residue energy level and low latency. Simulation results show that the SQR-AODV protocol achieves high reliability and stability and also long life time of the network, with high packet delivery ratio, high throughput, low energy consumption and considerable load balancing as compared to best-known on-demand protocol, AODV. Key words: Mobile ad hoc network, routing, ad hoc on-demand distance vector, quality of service.

Performance analysis of Dynamic MANET Ondemand (DYMO) Routing protocol

Routing in a MANET is challenging because of the dynamic topology and the lack of an existing fixed infrastructure. In such a scenario a mobile host can act as both a host and a router forwarding packets for other mobile nodes in the network. Routing protocols used in mobile ad hoc networks (MANET) must adapt to frequent or continual changes of topology, while simultaneously limiting the impact of tracking these changes on wireless resources. The DYMO protocol intended for the use by mobile nodes in wireless multihop ad hoc networks. It can adapt to the changing network topology and determine unicast routes between nodes within the network. This paper presents a comprehensive summarization and a comparative study of the Dynamic MANET On-demand (DYMO) protocol for MANET and simulation analysis of existing protocols DSR and AODV and comparison among them under varying number of nodes. Comparative study shows that DYMO is only a good choice if the nodes are mobile and wireless multihop. We have compared the performance of DSR and AODV with DYMO protocol by taking some performance metrics. Result shows that DYMO simulation provides better performance than DSR when compared in a given network topology with respect to throughput, packet loss, delay, packet delivery ratio, normalized routing load.

Wireless Ad-hoc Networks with On-dem and Cache Routing

This paper describes two novel routing algorithms that take into account the effect of distance between nodes and network congestion level on energy consumption. We formulate the routing problem as the minimization of energy Cost functions which reflect the key features of the problem under consideration. For route maintenance, we applied the least-recently used (LRU) replacement policy in caches to maintain route table and to remove the time-to-live parameter in some on-demand protocols such as Ad hoc on-demand distance vector (AODV). An on-demand routing protocol for mobile Ad hoc network (MANET) is one that searches for and tries to discover a route to some destination node only when a sending node generates a data packet addressed to that node. In order to avoid the need for such a route discovery to be performed before each data packet is sent, such routing protocols must cache previously discovered routes. But the cache itself may contain stale information due to nodes mobility. To solve the problem, we propose a new route cache scheme to improve the performance of route cache for finding more accurate and faster route to the destination. We developed an efficient algorithm for route discovery and management, and mobility handling for on demand cache routing on wireless mobile Ad hoc networks (MANET). We applied L-1 and L-2 route caches in each node to manage this algorithm efficiently. For mobility handling, we developed a sub-algorithm to handle node addition, deletion and movement in the network efficiently.

Multipath routing with spatial separation in wireless multi-hop networks without location information

We develop an on-demand multipath routing protocol for multi-hop wireless networks (MWNs), capable of finding spatially disjoint paths (paths physically distant from each other) without the need of location information. Multipath routing can enable various applications and enhancements in MWNs, such as load balancing, bandwidth aggregation, reliability and secure communications. The use of spatially disjoint routes is important to effectively achieve these gains, due to the non-interfering nature and distance of the paths. Most of the proposed multipath protocols for MWNs focus on reliability and do not find spatially separate paths. We propose a new on-demand protocol called Spatially Disjoint Multipath Routing (SDMR), capable of finding multiple paths in one route discovery, measuring the distance between them and choosing paths with most separation. A new distance metric is presented to measure path separation, which proves to be congruent with Euclidean distance across nodes in the paths. We develop a heuristic algorithm which, given a topology graph and utilizing the proposed distance metric, can discover spatially disjoint paths between any two nodes in the graph. To evaluate the protocol, we have studied the overhead both analytically in comparison with OLSR, and by simulation. The simulations also demonstrate the effectiveness of the protocol in finding spatially separate routes.

A Mobile Ad-Hoc Routing Algorithm with Comparative Study of Earlier Proposed Algorithms

A mobile ad-hoc network is an autonomous collection of mobile nodes that communicate over bandwidth constrained wireless links. Due to nodal mobility, the network topology may change rapidly and unpredictably over time. The routing protocols meant for wired network cannot be used for mobile ad-hoc network because of mobility of network. A number of routing protocols like Destination-Sequenced Distance-Vector (DSDV), Ad-Hoc On-Demand Distance Vector (AODV), Dynamic Source Routing (DSR), and Temporally Ordered Routing Algorithm have been implemented. The ad-hoc routing protocols can be divided into two classes; Table-Driven and On-Demand. This paper examines two routing protocols for mobile ad-hoc networks—the Destination Sequenced Distance Vector (DSDV), the table-driven protocol and the Ad-Hoc On- Demand Distance Vector routing (AODV), an on-demand protocol and propose an algorithm that facilitates efficient routing of the packet and failure recovery mechanism

Multiple Constraints for Ant Based Multicast Routing in Mobile Ad Hoc Networks

Problem statement: A Mobile Ad hoc Network (MANET) is one of the challenging environments for multicast. Since the associated overhead is more, the existing studies illustrate that tree-based and mesh-based on-demand protocols are not the best choice. The costs of the tree under multiple constraints are reduced by the several algorithms which are based on the Ant Colony Optimization (ACO) approach. The traffic-engineering multicast problem is treated as a single-purpose problem with several constraints with the help of these algorithms. The main disadvantage of this approach is the need of a predefined upper bound that can isolate good trees from the final solution. Approach: In order to solve the traffic engineering multicast problem which optimizes many objectives simultaneously this study offers a design on Ant Based Multicast Routing (AMR) algorithm for multicast routing in mobile ad hoc networks. Results: Apart from the existing constraints such as distance, delay and bandwidth, the algorithm calculates one more additional constraint in the cost metric which is the product of average-delay and the maximum depth of the multicast tree. Moreover it also attempts to reduce the combined cost metric. Conclusion: By simulation results, it is clear that our proposed algorithm surpasses all the previous algorithms by developing multicast trees with different sizes.

Associativity-Based On-Demand Multi-Path Routing In Mobile Ad Hoc Networks

This paper is primarily concerned with multi-path routing in Mobile Ad hoc Networks (MANETs). We propose a novel associativity-based on-demand source routing protocol for MANETs that attempts to establish relatively stable path(s) between the source and the destination. We introduce a new notion for gauging the temporal and spatial stability of nodes, and hence the paths interconnecting them. The proposed protocol is compared with other unipath (DSDV and AODV) and multi-path (AOMDV) routing protocols. We investigate the performance in terms of throughput, normalized routing overhead, packet delivery ratio etc. All on-demand protocols show good performance in mobile environments with less traffic overhead compared to proactive approaches, but they are prone to longer end-to-end delays due to route discovery and maintenance.

A Shoelace-Based QoS Routing Protocol for Mobile Ad Hoc Networks Using Directional Antenna

In this paper, we propose a new quality-of-service (QoS) routing protocol for mobile ad hoc network (MANET) using directional antennas. The proposed scheme offers a bandwidth-based routing protocol for QoS support in MANET using the concept of multi-path. Our MAC sub-layer adopts the CDMA-over-TDMA channel model. The on-demand QoS routing protocol calculates the end-to-end bandwidth and allocates bandwidth from the source node to the destination node. The paths are combined with multiple cross links, called shoelace, when the network bandwidth is strictly limited. Due to the property of the directional antenna, these cross links can transmit data simultaneously without any data interference. We develop a shoelace-based on-demand QoS routing protocol by identifying shoelaces in a MANET so as to construct a QoS route, which satisfied the bandwidth requirement, more easily. The shoelace-based route from the source to the destination is a route whose sub-path is constructed by shoelace structure. With the identified shoelaces, our shoelace-based scheme offers a higher success rate to construct a QoS route. Finally, simulation results demonstrate that the proposed routing protocol outperform existing QoS routing protocols in terms of success rate, throughput, and average latency.

On-demand multipath protocol with adaptive routing method by back propagation neural networks

Two representative multipath routing protocol strategies have been utilised currently, one is described as primary routing protocol and the other is load-balancing protocol. In the former routing protocol, the source selects the pre-computed shortest or fastest route as the primary one for the following data transmission. On the other hand, the latter routing protocol utilises multiple routes in rotation to equalise transmission load in the network. However, these solutions suffer during high mobility since they are lacking in global perspective for the following data transmission, resulting in low packet delivery ratio and prolonged delay time. Hence, to find the optimum routing protocol strategy, we present an adaptive multipath routing protocol by means of applying golden section search and back propagation neural networks. We evaluated our protocol using Omnet simulator. Simulation results show that the proposed solution has a good real-time performance than those of other protocols.