A comparative study of IEEE 802.11 MAC access mechanisms for different traffic types

The fast growth and development of wireless computer networks and multimedia applications make the Quality of Service (QoS) provided to their transmission an important issue. This paper aims to investigate the impact of varying the number of active stations on the network performance. This was carried out using different data rates. The investigations also considered both MAC protocol access mechanisms, i.e. the basic access and the Request To Send / Clear To Send (RTS/CTS). The effect of traffic type i.e. Constant Bit Rate (CBR) and Variable Bit Rate (VBR) traffics was also examined. The findings revealed that in large networks (larger than 15 stations), the RTS/CTS access mechanism outperformed the basic access mechanism since the performance of the latter was more sensitive to the increase and decrease of the number of active stations. Increasing the data rate improved the network performance in term of delay and jitter but it degraded the network performance in term of channel utilisation and packet loss ratio.