Rajashekhar C. Biradar

Review: Review of multicast routing mechanisms in mobile ad hoc networks

Frequent interactions among the group members of distributed wireless network environment may be facilitated with the help of Mobile Ad Hoc NETworks (MANETs). Some of the group-oriented applications include disaster management, battlefields, audio/video conferencing, e-commerce, e-education, etc. Group communication demands dynamic construction of efficient and reliable multicast routes under user mobility and varying channel conditions. Multicast routing mechanisms in MANETs have been consistently improved by researchers considering various performance measures such as energy efficient route establishment, packet delivery ratio, quicker and faster proactive route recovery, network life time, reliability, Quality of Service (QoS) based on bandwidth, delays, jitters, and security. The paper focuses on most recent reliable and QoS based multicast routing mechanisms that helps in multimedia communication over MANETs. The mechanisms are considered under different topological routing categories such as mesh, tree, zone and hybrid. We provide an overview of existing multicast routing mechanisms based on routing categories and point to directions for future research and development.

A survey on routing protocols in Wireless Sensor Networks

This paper presents a survey of state-of-the-art routing techniques in Wireless Sensor Networks (WSNs). Compared with traditional wireless networks, WSNs are characterized with denser levels of node deployment, higher unreliability of sensor nodes and severe power, computation and memory constraints. Various design challenges such as energy efficiency, data delivery models, quality of service, overheads etc., for routing protocols in WSNs are highlighted. We addressed most of the proposed routing methods along with scheme designs, benefits and result analysis wherever possible. The routing protocols discussed are classified into seven categories such as Data centric routing, Hierarchical routing, Location based routing, Negotiation based routing, Multipath based routing, Quality of Service (QoS) routing and Mobility based routing. This paper also compares the routing protocols against parameters such as power consumption, scalability, mobility, optimal routing and data aggregation. The paper concludes with possible open research issues in WSNs.

Link stability based multicast routing scheme in MANET

The group-oriented services are one of the primary application classes that are addressed by Mobile Ad hoc Networks (MANETs) in recent years. To support such services, multicast routing is used. Thus, there is a need to design stable and reliable multicast routing protocols for MANETs to ensure better packet delivery ratio, lower delays and reduced overheads. In this paper, we propose a mesh based multicast routing scheme that finds stable multicast path from source to receivers. The multicast mesh is constructed by using route request and route reply packets with the help of multicast routing information cache and link stability database maintained at every node. The stable paths are found based on selection of stable forwarding nodes that have high stability of link connectivity. The link stability is computed by using the parameters such as received power, distance between neighboring nodes and the link quality that is assessed using bit errors in a packet. The proposed scheme is simulated over a large number of MANET nodes with wide range of mobility and the performance is evaluated. Performance of the proposed scheme is compared with two well known mesh-based multicast routing protocols, i.e., on-demand multicast routing protocol (ODMRP) and enhanced on-demand multicast routing protocol (EODMRP). It is observed that the proposed scheme produces better packet delivery ratio, reduced packet delay and reduced overheads (such as control, memory, computation, and message overheads).

Fault tolerance in wireless sensor network using hand-off and dynamic power adjustment approach

Abstract Wireless Sensor Network (WSN) is deployed to monitor physical conditions in various places such as geographical regions, agriculture lands, office buildings, industrial plants and battlefields. WSNs are prone to different types of failures due to various environmental hazards like interference and internal failures (such as battery failure, processor failure, transceiver failure, etc). In such a situation, the sensed data cannot be transmitted correctly to the data center and the very purpose of deploying WSNs is not effective. Since it is difficult to monitor the network continuously through a manual operator, the nodes in WSN need to be capable of overcoming the failures and transmit the sensed data in proper order to the data center. Sensor network should be designed such that it should be able to identify the faulty nodes, try to rectify the fault and be able to transmit the sensed data to data center under faulty condition of a network and thereby make the network fault-free and thus enhance the fault tolerant capability. In this paper, we propose a novel idea of an Active node based Fault Tolerance using Battery power and Interference model (AFTBI) in WSN to identify the faulty nodes using battery power model and interference model. Fault tolerance against low battery power is designed through hand-off mechanism where in the faulty node selects the neighboring node having highest power and transfers all the services that are to be performed by the faulty node to the selected neighboring node. Fault tolerance against interference is provided by dynamic power level adjustment mechanism by allocating the time slot to all the neighboring nodes. If a particular node wishes to transmit the sensed data, it enters active status and transmits the packet with maximum power; otherwise it enters into sleep status having minimum power that is sufficient to receive hello messages and to maintain the connectivity. The performance evaluation is tested through simulation for packet delivery ratio, control overhead, memory overhead and fault recovery delay. We compared our results with Fault Detection in Wireless Sensor Networks (FDWSNs) for various performance measures and found that AFTBI outperforms compared to the results of FDWSN.

Neighbor supported reliable multipath multicast routing in MANETs

The limited battery power, unpredictable mobility and large variation of received signal strength in nodes of Mobile Ad Hoc Networks (MANETs) create link and node vulnerability and instability. Multicast routing in MANETs for group communication requires the establishment of reliable links between neighboring nodes called as reliability pair beginning from the source and extending such reliability pairs enroute to the destination. We propose a scheme for Multipath Multicast Routing in MANETs using reliable Neighbor Selection (MMRNS) mechanism. A mesh of multipath routes are established from source to multicast destinations using neighbors that have high reliability pair factor. MMRNS operates in the following phases. (1) Computation of reliability pair factor based on node power level, received differential signal strength between the nodes and mobility. (2) Pruning neighbor nodes that have reliability pair factor smaller than a threshold. (3) Discovery of multipath multicast mesh routes with the help of request and reply packets. (4) Multipath priority assignment based on minimum value of reliability pair factor of a path and information transfer from source to the multicast destinations and (5) route maintenance against link/node failures. The scheme is simulated to evaluate the performance parameters like packet delivery ratio, memory overhead, message overhead, control overhead and packet delays in comparison to the mesh based multicast routing protocols such as On-demand Multicast Routing Protocol (ODMRP) and Enhanced ODMRP (EODMRP). MMRNS performs better than ODMRP and EODMRP as observed from the simulation results.

Mesh Based Multicast Routing in MANET: Stable Link Based Approach

—The group-oriented services are one of the primary application classes that are addressed by mobile ad hoc networks (MANETs) in recent years. To support such services, multicast routing is used. Thus, there is a need to design stable and reliable multicast routing protocols for MANETs to ensure better packet delivery ratio, lower delays and reduced control overheads. In this paper, we propose a mesh based multicast routing scheme that finds stable multicast path from source to receivers. The multicast mesh is constructed by using route request and route reply packets with the help of multicast routing information cache and link stability database maintained at every node. The stable paths are found based on selection of stable forwarding nodes that have high stability of link connectivity. The link stability is computed by using the parameters such as received power, distance between neighboring nodes and the link quality assessed using bit errors in a packet. The proposed scheme is simulated over a large number of MANET nodes with wide range of mobility and the performance is evaluated. It is observed that proposed scheme produces better packet delivery ratio, less control overheads and reduced packet delay compared to on-demand multicast routing protocol (ODMRP).

Survey of Bandwidth Estimation Techniques in Communication Networks

Increased popularity and wealth-creation potential of conventional mobile phones, smart phones and tablet computers resulted in the unprecedented penetration of wired and wireless communications. Most of such real-time applications require video streaming that needs quality of service (QoS) provisioning in addition to good end-to-end transport performance in network infrastructure. Estimating the reliability of an end-to-end network path is critically important for such applications. Available bandwidth at a node is an important QoS characteristic of the path that is a minimum spare capacity of links constituting a network path. Researchers have proposed various techniques for estimating the bandwidth to increase the network throughput. In the past, bandwidth estimation (BE) techniques developed for wired networks are focused on point-to point dedicated links that are not directly usable in wireless networks. The reason is that these techniques are based on models which are no longer valid in wireless environment. This paper aims to provide a comprehensive survey of the BE techniques proposed till date by researchers in the literature for both wired and wireless networks. We have categorized the BE techniques into four main categories as active probing techniques, passive techniques, techniques only for wireless networks and other BE techniques. A brief outline of each technique is discussed which includes the problem statement, operation methodology, results and applications. Techniques in each category have been compared using various parameters such as accuracy, BE time and overhead.

Ring Mesh Based Multicast Routing Scheme in MANET Using Bandwidth Delay Product

Quality of Service (QoS) support in Mobile Ad Hoc Networks (MANETs) for group communication necessitates design of reliable networks with multicast support mechanisms. Reliable network connectivity among MANET nodes require high quality links that have much less packet drops and reliable nodes considering node mobility and failures. Reliability of a network can be enhanced by designing an end-to-end network pipe that satisfies the required QoS in terms of in-flight packets from source to a destination as well as by using a path comprising of reliable nodes. In-flight packets may be computed by using bandwidth delay product (BDP) of a network pipe. To meet the QoS requirements of an application, BDP should be maintained stable irrespective of vibrant network conditions. In this paper, we propose a BDP based multicast routing scheme in MANET using reliable ring mesh backbone. The scheme operates in the following sequence. (1) Reliable node pairs are computed based on mobility, remaining battery power and differential signal strength. The node pairs also compute BDP between them. BDP of a reliability pair is assessed using available bandwidth and delay experienced by a packet between them. (2) Backbone ring mesh is constructed using reliable pair nodes and convex hull algorithm. Reliable ring mesh is constructed at an arbitrary distance from the centroid of the MANET area. (3) Multicast paths are found by discovering a path from source to each destination of the group with concatenated set of reliability pairs that satisfy the BDP requirement. (4) The ring mesh maintains high BDP on ring links and can recover in case of node mobility and failures. Results show that there is an improvement in terms of end-to-end delay, packet delivery ratio, control overhead, memory overhead and application rejection ratio as compared to the Enhanced On Demand Multicast Routing Protocol.

Agent-driven backbone ring-based reliable multicast routing in mobile ad hoc networks

Routing in mobile ad hoc networks (MANETs) for groups should aim at providing reliable and robust multicast routes to the group members against link failures, node failures and mobility conditions. The authors propose an agent-based multicast routing scheme in MANET that builds a backbone in the form of a reliable ring and finds multicast routes. The authors use the convex hull algorithm to find the outer boundary of the network area that helps in creating a reliable ring at an optimum distance between the centroid and outer boundary. The reliability of such a backbone is modelled by using reliable links based on the probabilistic measure of link failures. Later, a mesh of multicast routes are found by connecting: (i) source to sources nearest ring node and (ii) destination to destinations nearest ring node. The scheme consists of a set of static and mobile agents, which coordinate through knowledge base and identify links to form a reliable ring at an optimal distance from the centre of MANET area. Agents are also used to recover routes against link failures, node failures and mobility of nodes with local patching of failed links/nodes. The results show that there is an improvement in control overheads, packet delivery ratio, group reliability and packet delivery latency as compared to two protocols: (i) on demand multicast routing protocol and (ii) agent-based multicast routing scheme in MANETs.

A Miniaturized Volkswagen Logo UWB Antenna with Slotted Ground Structure and Metamaterial for GPS, WiMAX and WLAN Applications

A novel concept of using slotted ground structure and a single circular split ring resonator (SRR) to achieve multiband operation from a miniaturized UWB antenna is presented in this paper. Initially, a miniaturized Volkswagen logo ultrawideband (UWB) antenna having −10 dB impedance bandwidth of about 124% (2.9–12.4 GHz) in simulation and 116.7% (3.1–11.8 GHz) under measurement is designed. This miniaturization leads to about 10% increment in −10 dB reflection coefficient bandwidth and about 66.71% reduction in the volume of the proposed UWB antenna as compared to the conventional circular antenna. In order to reconfigure the proposed UWB antenna to operate it at 1.5 (GPS), 3.5 (WiMAX), 5.2 and 5.8GHz (WLAN) frequency bands, slotted ground structure with metamaterial is used. The proposed metamaterial is a circular SRR consisting of a single circular ring and is placed on the slotted ground structure of the proposed antenna to achieve 1.5GHz band. The proposed configuration has a volume of 0.290λ0 × 0.290λ0 × 0.015λ0 (30 × 30 × 1.6mm3) at a lower resonating band of 2.9GHz and is fabricated on a widely available FR4 substrate with a loss tangent of 0.02 and dielectric constant of 4.4. Simulated and experimental results show that the proposed design yields S11 < −10 dB at the targeted frequencies. Good impedance matching, stable radiation characteristics with cross-polarization level less than −15 dB (both in E and H planes), VSWR < 2, average gain of 3.09 dBi and radiation efficiency of more than 85% are observed at the designed band when the antenna is fabricated and tested.