A testbed for MANETs: Implementation, experiences and learned lessons

In this paper, we present the implementation, experiences and lessons learned of our tesbed for Ad-hoc networks and Mobile Ad hoc Networks (MANETs). We used OLSR protocol for real experimental evaluation. We investigate the effect of mobility and topology changing in the throughput of a MANET. We study the impact of best-effort traffic for Mesh Topology and Linear Topology. In this work, we consider eight experimental models and we assess the performance of our testbed in terms of throughput, round trip time and packet loss. We found that some of the OLSR's problems can be solved, for instance the routing loop, but this protocol still has the self-interference problem. Also, there is an intricate interdependence between MAC layer and routing layer. We carried out the experiments considering stationary nodes of an Ad-hoc network and the node mobility of MANETs. We found that throughput of TCP was improved by reducing Link Quality Window Size (LQWS). For TCP data flow, we got better results when the LQWS value was 10. Moreover, we found that the node join and leave operations increase the packet loss. The OLSR protocol has a good performance when the source node is moving. However, the performance is not good when the relay nodes are moving.Peer ReviewedPostprint (published version

ROUTING IN MOBILE AD-HOC NETWORKS: SCALABILITY AND EFFICIENCY

Mobile Ad-hoc Networks (MANETs) have received considerable research interest in recent years. Because of dynamic topology and limited resources, it is challenging to design routing protocols for MANETs. In this dissertation, we focus on the scalability and efficiency problems in designing routing protocols for MANETs. We design the Way Point Routing (WPR) model for medium to large networks. WPR selects a number of nodes on a route as waypoints and divides the route into segments at the waypoints. Waypoint nodes run a high-level inter-segment routing protocol, and nodes on each segment run a low-level intra-segment routing protocol. We use DSR and AODV as the inter-segment and the intra-segment routing protocols, respectively. We term this instantiation the DSR Over AODV (DOA) routing protocol. We develop Salvaging Route Reply (SRR) to salvage undeliverable route reply (RREP) messages. We propose two SRR schemes: SRR1 and SRR2. In SRR1, a salvor actively broadcasts a one-hop salvage request to find an alternative path to the source. In SRR2, nodes passively learn an alternative path from duplicate route request (RREQ) packets. A salvor uses the alternative path to forward a RREP when the original path is broken. We propose Multiple-Target Route Discovery (MTRD) to aggregate multiple route requests into one RREQ message and to discover multiple targets simultaneously. When a source initiates a route discovery, it first tries to attach its request to existing RREQ packets that it relays. MTRD improves routing performance by reducing the number of regular route discoveries. We develop a new scheme called Bilateral Route Discovery (BRD), in which both source and destination actively participate in a route discovery process. BRD consists of two halves: a source route discovery and a destination route discovery, each searching for the other. BRD has the potential to reduce control overhead by one half. We propose an efficient and generalized approach called Accumulated Path Metric (APM) to support High-Throughput Metrics (HTMs). APM finds the shortest path without collecting topology information and without running a shortest-path algorithm. Moreover, we develop the Broadcast Ordering (BO) technique to suppress unnecessary RREQ transmissions

Analysis and Modeling Experiment Performance Parameters of Routing Protocols in MANETs and VANETs

In this paper, a framework for experimental parameters in which Packet Delivery Ratio (PDR), effect of link duration over End-to-End Delay (E2ED) and Normalized Routing Overhead (NRO) in terms of control packets is analyzed and modeled for Mobile Ad-Hoc NETworks (MANETs) and Vehicular Ad-Hoc NETworks (VANETs) with the assumption that nodes (vehicles) are sparsely moving in two different road. Moreover, this paper contributes the performance comparison of one Proactive Routing Protocol; Destination Sequenced Distance vector (DSDV) and two reactive protocols; DYnamic Source Routing (DSR) and DYnamic MANET On-Demand (DYMO). A novel contribution of this work is enhancements in default versions of selected routing protocols. Three performance parameters; PDR, E2ED and NRO with varying scalabilities are measured to analyze the performance of selected routing protocols with their original and enhanced versions. From extensive simulations, it is observed that DSR outperforms among all three protocols at the cost of delay. NS-2 simulator is used for simulation with TwoRayGround propagation model to evaluate analytical results

Flexible cross layer design for improved quality of service in MANETs

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel UniversityMobile Ad hoc Networks (MANETs) are becoming increasingly important because of their unique characteristics of connectivity. Several delay sensitive applications are starting to appear in these kinds of networks. Therefore, an issue in concern is to guarantee Quality of Service (QoS) in such constantly changing communication environment. The classical QoS aware solutions that have been used till now in the wired and infrastructure wireless networks are unable to achieve the necessary performance in the MANETs. The specialized protocols designed for multihop ad hoc networks offer basic connectivity with limited delay awareness and the mobility factor in the MANETs makes them even more unsuitable for use. Several protocols and solutions have been emerging in almost every layer in the protocol stack. The majority of the research efforts agree on the fact that in such dynamic environment in order to optimize the performance of the protocols, there is the need for additional information about the status of the network to be available. Hence, many cross layer design approaches appeared in the scene. Cross layer design has major advantages and the necessity to utilize such a design is definite. However, cross layer design conceals risks like architecture instability and design inflexibility. The aggressive use of cross layer design results in excessive increase of the cost of deployment and complicates both maintenance and upgrade of the network. The use of autonomous protocols like bio-inspired mechanisms and algorithms that are resilient on cross layer information unavailability, are able to reduce the dependence on cross layer design. In addition, properties like the prediction of the dynamic conditions and the adaptation to them are quite important characteristics. The design of a routing decision algorithm based on Bayesian Inference for the prediction of the path quality is proposed here. The accurate prediction capabilities and the efficient use of the plethora of cross layer information are presented. Furthermore, an adaptive mechanism based on the Genetic Algorithm (GA) is used to control the flow of the data in the transport layer. The aforementioned flow control mechanism inherits GA’s optimization capabilities without the need of knowing any details about the network conditions, thus, reducing the cross layer information dependence. Finally, is illustrated how Bayesian Inference can be used to suggest configuration parameter values to the other protocols in different layers in order to improve their performance.National Foundation of Scholarships of Greece(I.K.Y.

Towards an Optimized Traffic-Aware Routing in Wireless Mesh Networks

International audienceIn this paper we study through simulations the impact of PHY/MAC protocols on higher layers. In a comparative way, we investigate the effectiveness of some protocols when they coexist on a wireless mesh network environment. Results show that PHY/MAC parameters have an important impact on routing performances. Based on these results, we propose two tra c-aware routing metrics based on link availability. The information about the link availability/occupancy is picked up from lower layers using a cross-layer approach. The rst metric is load-sensitive and aims to balance the tra c load according to the availability of a link to support additional ows. The second metric reproduces better the capacity of a link since it is based on its residual bandwidth. Using several real experiments, we have shown that our proposals can accurately determine better paths in terms of throughput and delay. Our experiments are carried out into an heterogeneous IEEE 802.11n based network running with OLSR routing protocol

Mobile Ad Hoc Networks

Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility of mobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms