E-BEB algorithm to improve Quality of Service on Wireless Ad-Hoc Networks

Al-Hubaishi, Mohammed Hussein

http://hdl.handle.net/10400.1/10587

Use this identifier to reference this record.

Name:	Description:	Size:	Format:
Mohammed´s Thesis.pdf		3.81 MB	Adobe PDF	Download

Send Feedback

Authors

Al-Hubaishi, Mohammed Hussein

Advisor(s)

Berqia, Amine

Abstract(s)

The medium access control (MAC) protocol is the main element which determines the system throughput in wireless local area networks WLANs like IEEE 802.11 standard. The MAC technique of the IEEE 802.11 protocol is called Distributed Coordination Function (DCF). In DCF, stations contend for the use of the channel in distributed manner via the use of the Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) protocol. In the CSMA/CA protocol, each station sets up a Backoff time according to a randomly selected interval from zero to the Contention Window (CW) for an additional deferral time before transmitting. The random Binary Exponential Backoff (BEB) algorithm is used to randomize moments at which stations try to access the wireless medium. However, in the random Backoff mechanism, packet collisions are not completely eliminated and the system throughput decreases when the number of stations is large and there is no fairness between stations. The BEB has a number of disadvantages; one major disadvantage is the problem of fairness. In this Master Thesis, we analyze the behavior of the BEB algorithm used in IEEE 802.11 standard. We propose an Enhanced Binary Exponential Backoff (E-BEB) algorithm to improve the fairness of the channel access for BEB algorithms. Our algorithm E-BEB adjusts the way of increase or decrease of the contention window CW based on the number of frame which is sent successfully. We propose several configurations and we use NS2 simulator to analyze the network's fairness of the channel access of the E-BEB algorithm. The simulation results show that compared with others algorithms like BEB or Improved BEB (I-BEB), the E-BEB algorithm can improve the fairness of the channel access and increase the network's throughput capacity at the same time which is a very important Quality of Service QoS parameter.