A Novel Adaptively Dynamic Tuning of the Contention Window (CW)for Distributed Coordination Function in IEEE 802.11 Ad hoc Networks

Designing new protocols for Mobile Ad hoc Networks (MANETs) is a great challenge due to their distributed and self organized nature. Though, aspects of approved algorithms for hierarchical topographies may be carried over to these flat networks. The IEEE 802.11 protocol supports ad hoc networks in small scale applications, but its performance in large scale environments is still under investigation. Besides the Distributed Coordination Function (DCF), the Timer Synchronization Function (TSF) can be significantly improved in order to increase the performance in large scale multihop networks. This article presents systematic extensions to the TSF that allow increasing the overall reliability and disburdening the network at the same time. The presented scheme may be tailored to specific applications and even supports mobile stations and herewith MANETs.

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Improving WLAN Performance by Modifying an IEEE 802.11 Protocol

Security, Design, and Architecture for Broadband and Wireless Network Technologies ◽

10.4018/978-1-4666-3902-7.ch002 ◽

2013 ◽

pp. 15-32

Author(s):

Nurul I. Sarkar

Keyword(s):

Ieee 802.11 ◽

Ad Hoc ◽

Packet Delay ◽

Distributed Coordination ◽

Bandwidth Utilization ◽

Medium Access ◽

802.11 Dcf ◽

802.11 Networks ◽

Distributed Coordination Function ◽

Coordination Function

One of the limitations of the IEEE 802.11 distributed coordination function (DCF) protocol is its low bandwidth utilization under medium-to-high traffic loads resulting in low throughput and high packet delay. To overcome performance problems, traditional IEEE 802.11 DCF (“DCF”) protocol is modified to the buffer unit multiple access (BUMA) protocol. The BUMA protocol achieves a better system performance by introducing a temporary buffer unit at the medium access control (MAC) layer to accumulate multiple packets and combine them into a single packet (with a header and a trailer) before transmission. This paper provides an in-depth performance evaluation (by simulation) of BUMA for multiuser ad hoc and infrastructure networks. Results obtained show that the BUMA is more efficient than that of DCF. The BUMA protocol is simple and its algorithm (software) can be upgraded to 802.11 networks requiring no hardware changes. The BUMA protocol is described and simulation results are presented to verify the performance.

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Interconnection Issues in CPS

Challenges, Opportunities, and Dimensions of Cyber-Physical Systems - Advances in Systems Analysis, Software Engineering, and High Performance Computing ◽

10.4018/978-1-4666-7312-0.ch004 ◽

2015 ◽

pp. 61-75

Keyword(s):

Wireless Networks ◽

Mobile Networks ◽

Ad Hoc ◽

Multicast Routing ◽

Distributed Coordination ◽

Multicast Communication ◽

Distributed Coordination Function ◽

Network Properties ◽

Hoc Networks ◽

Coordination Function

This chapter shows the interconnection issues in different wireless networks such as ad hoc networks and sensor networks. It also specifies the need for multicast routing protocols in mobile networks, because these wireless networks are suitable for multicast communication due to its inherent transmission ability. Based on the area to be covered, mechanism used for sensor deployment, and various properties of sensor network properties, different coverage formulations have been suggested. In addition, several constructions reachable areas and their expectations along with an outline of the explanations are described. Though 802.11 planned for organization-based systems, the Distributed Coordination Function (DCF) offered in 802.11 permits mobile networks to communicate with the channel exclusive of the base location. Several performance issues related to IEEE 802.11 are revealed. This chapter identifies the main reasons for performance losses and provides solutions for the scenarios that are specific to certain issues related to CPS.

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