TCP over geo-routing for high mobility: vehicle grids and airborne swarms

Ad hoc wireless networks have become the architecture of choice for peer to peer communications in areas where the telecommunications infrastructure is inadequate or has failed. A major challenge is the reliable delivery of data when nodes move. The reliable Internet protocol is TCP. However, TCP performs poorly in mobile ad hoc networks, mainly because of route breakage. To overcome this problem, a robust routing protocol must be used. To this effect, Geo-routing has recently received attention in large scale, mobile systems as it does not require end- to-end path establishment and pre-computed packet forwarding routing structure at nodes. These properties make Geo-routing robust to highly dynamic route changes. For best performance, however, several parameters must be carefully tuned. In this paper we study the joint optimization of TCP and Geo-routing parame- ters to handle high speeds. We first introduce two highly mobile ad hoc scenarios that require reliable delivery, namely the vehicle urban grid and the airborne swarms. Then, we study the impact of critical system parameters (e.g., hello message ex- change rate, delay timer in TCP for out-of-order delivery, etc) on the performance of both UDP and TCP. We improve hello message effciency in Geo-routing by using an adaptive hello exchange scheme. Then, we fix the out-of-order problem in TCP by using a receiver-side out-of-order detection and delayed ack strategy. We show that these parameter adjustments are critical for effcient TCP over Geo-routing in highly mobile applications. With these enhancements our TCP with Geo-routing solution easily outperforms TCP over traditional ad hoc routing schemes, such as AODV.1st IFIP International Conference on Ad-Hoc NetWorkingRed de Universidades con Carreras en Informática (RedUNCI

TCP over geo-routing for high mobility: vehicle grids and airborne swarms

Ad hoc wireless networks have become the architecture of choice for peer to peer communications in areas where the telecommunications infrastructure is inadequate or has failed. A major challenge is the reliable delivery of data when nodes move. The reliable Internet protocol is TCP. However, TCP performs poorly in mobile ad hoc networks, mainly because of route breakage. To overcome this problem, a robust routing protocol must be used. To this effect, Geo-routing has recently received attention in large scale, mobile systems as it does not require end- to-end path establishment and pre-computed packet forwarding routing structure at nodes. These properties make Geo-routing robust to highly dynamic route changes. For best performance, however, several parameters must be carefully tuned. In this paper we study the joint optimization of TCP and Geo-routing parame- ters to handle high speeds. We first introduce two highly mobile ad hoc scenarios that require reliable delivery, namely the vehicle urban grid and the airborne swarms. Then, we study the impact of critical system parameters (e.g., hello message ex- change rate, delay timer in TCP for out-of-order delivery, etc) on the performance of both UDP and TCP. We improve hello message effciency in Geo-routing by using an adaptive hello exchange scheme. Then, we fix the out-of-order problem in TCP by using a receiver-side out-of-order detection and delayed ack strategy. We show that these parameter adjustments are critical for effcient TCP over Geo-routing in highly mobile applications. With these enhancements our TCP with Geo-routing solution easily outperforms TCP over traditional ad hoc routing schemes, such as AODV.1st IFIP International Conference on Ad-Hoc NetWorkingRed de Universidades con Carreras en Informática (RedUNCI

A survey of performance enhancement of transmission control protocol (TCP) in wireless ad hoc networks

This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Springer OpenTransmission control protocol (TCP), which provides reliable end-to-end data delivery, performs well in traditional wired network environments, while in wireless ad hoc networks, it does not perform well. Compared to wired networks, wireless ad hoc networks have some specific characteristics such as node mobility and a shared medium. Owing to these specific characteristics of wireless ad hoc networks, TCP faces particular problems with, for example, route failure, channel contention and high bit error rates. These factors are responsible for the performance degradation of TCP in wireless ad hoc networks. The research community has produced a wide range of proposals to improve the performance of TCP in wireless ad hoc networks. This article presents a survey of these proposals (approaches). A classification of TCP improvement proposals for wireless ad hoc networks is presented, which makes it easy to compare the proposals falling under the same category. Tables which summarize the approaches for quick overview are provided. Possible directions for further improvements in this area are suggested in the conclusions. The aim of the article is to enable the reader to quickly acquire an overview of the state of TCP in wireless ad hoc networks.This study is partly funded by Kohat University of Science & Technology (KUST), Pakistan, and the Higher Education Commission, Pakistan

Design & Evaluation of Path-based Reputation System for MANET Routing

Most of the existing reputation systems in mobile ad hoc networks (MANET) consider only node reputations when selecting routes. Reputation and trust are therefore generally ensured within a one-hop distance when routing decisions are made, which often fail to provide the most reliable, trusted route. In this report, we first summarize the background studies on the security of MANET. Then, we propose a system that is based on path reputation, which is computed from reputation and trust values of each and every node in the route. The use of path reputation greatly enhances the reliability of resulting routes. The detailed system architecture and components design of the proposed mechanism are carefully described on top of the AODV (Ad-hoc On-demand Distance Vector) routing protocol. We also evaluate the performance of the proposed system by simulating it on top of AODV. Simulation experiments show that the proposed scheme greatly improves network throughput in the midst of misbehavior nodes while requires very limited message overhead. To our knowledge, this is the first path-based reputation system proposal that may be implemented on top of a non-source based routing scheme such as AODV

FastM: Design and Evaluation of a Fast Mobility Mechanism for Wireless Mesh Networks

Although there is a large volume of work in the literature in terms of mobility approaches for Wireless Mesh Networks, usually these approaches introduce high latency in the handover process and do not support realtime services and applications. Moreover, mobility is decoupled from routing, which leads to inefficiency to both mobility and routing approaches with respect to mobility. In this paper we present a new extension to proactive routing protocols using a fast mobility extension, FastM, with the purpose of increasing handover performance in Wireless Mesh Networks. With this new extension, a new concept is created to integrate information between neighbor wireless mesh routers, managing locations of clients associated to wireless mesh routers in a certain neighborhood, and avoiding packet loss during handover. The proposed mobility approach is able to optimize the handover process without imposing any modifications to the current IEE 802.11 MAC protocol and use unmodified clients. Results show the improved efficiency of the proposed scheme: metrics such as disconnection time, throughput, packet loss and control overhead are largely improved when compared to previous approaches. Moreover, these conclusions apply to mobility scenarios, although mobility decreases the performance of the handover approach, as expected