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

Multiband CSMA/CA with RTS-CTS strategy

We present in this paper a new medium access control (MAC) scheme devoted to orthogonal frequency division multiple access (OFDMA) systems which aims at reducing collision probabilities during the channel request period. The proposed MAC relies on the classical carrier sense multiple access/collision avoidance (CSMA/CA) protocol with RTS / CTS ("Request To Send" / "Clear To Send") mechanism. The proposed method focus on the collision probability of RTS messages exploiting a multi-channel configuration for these messages while using the whole band for data transmissions. The protocol may be interpreted as an asynchronous frequency multiplexing of RTS messages. This method achieves strong performance gains in terms of throughput and latency especially in crowded networks. Index Terms-Carrier sense multiple access/collision avoidance (CSMA/CA), multiband, throughput, MAC protocol

Evaluating Hamming Distance as a Metric for the Detection of CRC-based Side-channel Communications in MANETs

AbstractSide-channel communication is a form of traffic in which malicious parties communicate secretly over a wireless network. This is often established through the modification of Ethernet frame header fields, such as the Frame Check Sequence (FCS). The FCS is responsible for determining whether or not a frame has been corrupted in transmission, and contains a value calculated through the use of a predetermined polynomial. A malicious party may send messages that appear as nothing more than naturally corrupted noise on a network to those who are not the intended recipient. We use a metric known as Hamming distance in an attempt to differentiate purposely corrupted frames from naturally corrupted ones. In theory, it should be possible to recognize purposely corrupted frames based on how high this Hamming distance value is, as it signifies how many bits are different between the expected and the received FCS values. It is hypothesized that a range of threshold values based off of this metric exist, which may allow for the detection of side-channel communication across all scenarios. We ran an experiment with human subjects in a foot platoon formation and analyzed the data using a support vector machine. Our results show promise on the use of Hamming distance for side-channel detection in MANETs

Improving Channel Throughput of WLANs and Ad Hoc Networks Using Explicit Denial of Requests

A new Multiple Access Control scheme for wireless ad hoc networks and WLANs is proposed. This scheme uses explicit denial of channel requests and a busy tone to improve channel throughput. Performance analysis shows significant improvement when the network is under heavy traffic load

Secure MAC protocols for cognitive radio networks

A thesis submitted in partial fulfilment for the degree of Doctor of PhilosophyWith the rapid increase in wireless devices, an effective improvement in the demand of efficient spectrum utilisation for gaining better connectivity is needed. Cognitive Radio (CR) is an emerging technology that exploits the inefficient utilisation of the unused spectrum dynamically. Since spectrum sharing is responsible for coordinating channels’ access for Cognitive Users (CUs), the Common Control Channel (CCC) is one of the existing methods used to exchange the control information between CUs. However, the unique characteristics and parameters of Cognitive Radio Networks (CRNs) present several possible threats targeting spectrum sensing, spectrum management, spectrum sharing, and spectrum mobility leading to the deterioration of the network performance. Thus, protection and detection security mechanisms are essential to maintaining the CRNs. This thesis presents a novel decentralised CR MAC protocol that successfully utilises the unused portion of the licensed band. The protocol achieves improved performance; communication time and throughput when compared to two benchmark protocols. Less communication time and higher throughput are accomplished by the protocol due to performing fast switching to the selected available data channel for initiating data transmission. The proposed protocol is then extended to two different versions based on two authentication approaches applied to it; one using Digital Signature and another is based on Shared-Key. The two proposed secure protocols address the security requirements in CRNs leading to subsequent secure communication among CUs. The protocols function effectively in providing defence against several attacks related to the MAC layer such as; Spectrum Sensing Data Manipulation/Falsification, Data Tempering and Modification, Jamming attacks, Eavesdropping, Forgery and Fake control information attacks, MAC address spoofing, and unauthorised access attacks. The associated security algorithms ensure the successful secure communication between CUs in a cooperative approach. Moreover, the security protocols are investigated and analysed in terms of security flows by launching unauthorised access and modification attacks on the transmitted information. The testing results demonstrated that two protocols perform successful detection of threats and ensure secure communication in CRNs