In this paper we introduce different types of access mechanism which contains distributed coordination function (DCF) and point coordination function (PCF) in Media Access Control (MAC) layer of Wireless Local Area Network (WLAN). In order to analyze the influence to the performance of WLAN, we take a part of oil field as a background to establish WLAN model based on OPNET software. After simulation, different results which could evaluate the performance of WLAN are obtained by comparison of DCF and DCF/PCF access mechanism. The results of simulations illustrate that performance of PCF access mode is stabilized relatively when there is a large scale of network At the same time, using DCF/PCF can combine the advantages of two different access mechanism.
