Novel mechanisms for quality of service improvements in wireless ad hoc networks

  • Authors:

  • Mohammad S. Saraireh;Nidal A. Al-Dmour

  • Affiliations:

  • Computer Engineering Department, Faculty of Engineering, Mutah University, Mutah, Jordan;Computer Engineering Department, Faculty of Engineering, Mutah University, Mutah, Jordan

  • Venue:
  • WSEAS TRANSACTIONS on SYSTEMS
  • Year:
  • 2011

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Abstract

This paper proposes two mechanisms for improving the IEEE 802.11 DCF protocol performance and for enhancing QoS in IEEE 802.11 wireless LANs. These are Ratio based and Collision Rate Variation (CRV) schemes. The Ratio based scheme uses the collision rate value of the current and the past history of the network conditions to adaptively adjust the Contention Window (CW) size for each individual station. The CRV scheme also employs the collision rate and collision rate variation values to adjust the CW value locally for each individual station based on the current and previous network conditions. The aim of developing these approaches is to reduce the probability of collisions among the contending stations in a heavily loaded network in an attempt to improve QoS in IEEE 802.11 DCF protocol. The proposed schemes are evaluated and compared with the conventional IEEE 802.11 DCF and the Exponential Increase Exponential Decrease (EIED) schemes. The evaluation is carried out for different scenarios (i.e. different traffic load and different network size) using the ns-2 simulator. The metrics used in the evaluation are delay, jitter, throughput, packet loss, protocol efficiency, and collision rate. The results indicate that the best performance is achieved by using the proposed schemes with superiority for the CRV scheme in most cases.