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

Enhancing Performance by Salvaging Route Reply Messages in On-Demand Routing Protocols for MANETs

Researchers prefer on-demand routing protocols in mobile ad hoc networks where resources such as energy and bandwidth are constrained. In these protocols, a source discovers a route to a destination typically by flooding the entire or a part of the network with a route request (RREQ) message. The destination responds by sending a route reply (RREP) message to the source. The RREP travels hop by hop on the discovered route in the reverse direction or on another route to the source. Sometimes the RREP can not be sent to the intended next hop by an intermediate node due to node mobility or network congestion. Existing on-demand routing protocols handle the undeliverable RREP as a normal data packet - discard the packet and initiate a route error message. This is highly undesirable because a RREP message has a lot at stake – it is obtained at the cost of a large number of RREQ transmissions, which is an expensive and timeconsuming process. In this paper, we propose the idea of salvaging route reply (SRR) to improve the performance of on-demand routing protocols. We present two schemes to salvage an undeliverable RREP. Scheme one actively sends a one-hop salvage request message to find an alternative path to the source, while scheme two passively maintains a backup path to the source. Furthermore, we present the design of two SRR schemes in AODV and prove that routes are loop-free after a salvaging. We conduct extensive simulations to evaluate the performance of SRR, and the simulation results confirm the effectiveness of the SRR approach

Energy Aware Routing Protocol for Energy Constrained Mobile Ad-hoc Networks

Dynamic topology change and decentralized makes routing a challenging task in mobile ad hoc network. Energy efficient routing is the most challenging task in MANET due to limited energy of mobile nodes. Limited power of batteries typically use in MANET, and this is not easy to change or replace while running communication. Network disorder can occur for many factors but in middle of these factors deficiency of energy is the most significant one for causing broken links and early partition of the network. Evenly distribution of power between nodes could enhance the lifetime of the network, which leads to improving overall network transmission and minimizes the connection request. To discourse this issue, we propose an Energy Aware Routing Protocol (EARP) which considers node energy in route searching process and chooses nodes with higher energy levels. The EARP aim is to establish the shortest route from source to destination that contains energy efficient nodes. The performance of EARP is evaluated in terms of packet delivery ratio, network lifetime, end-to-end delay and throughput. Results of simulation done by using NS2 network simulator shows that EARP can achieve both high throughput and delivery ratio, whereas increase network lifetime and decreases end-to-end delay

A hop-count and node energy based manet routing protocol

Mobile ad hoc network is a self-configuring network in which all participating nodes are mobile and consist of limited channel bandwidth and energy. Mobile devices are battery operated, and energy efficiency is a major issue for battery-operated devices in mobile ad hoc networks. Routing data packets from source to destination is the challenging task in mobile ad hoc networks due to node mobility and dynamic topology change in the network. Link failure or node energy depletion causes re-routing and establishing a new route from the source node to destination node which consumes extra node energy, reduces connectivity of the network and early partition of the network. Energy-related parameters consideration in routing is an important solution to enhance network lifetime. Several better performing routing schemes are presented and implemented for MANETs. Ad-hoc On-demand Distance Vector (AODV) routing protocol is one which performs well among similar routing protocols for MANET. AODV route selection base on either lowest hop-count or fresh sequence number. Many enhancements to AODV are proposed, which represents a better performance in comparison with original protocol. However, in a large network different paths to the destination could be found with the same hop-count. When efficiency is deliberated for those paths in quickly data transmission, each path performance varies in terms of throughput, end-to-end delay and packet delivery ratio due to the mobility of the nodes in the network. AODV routing protocol and enhancements suggested by other researchers do not give attention to such cases, and this paper proposes Hop-count and Node Energy based Routing Protocol (HNERP) which uses a multi-function routing strategy that incorporates with hop-count and node energy while making the routing decision. The proposed protocol is simulated by using NS2 and results show that HNERP performs better in term of packet delivery ratio and throughput, moreover it increases network lifetime and reduces end-to-end delay