Performance Analysis of IEEE 802.11 DCF Based on OFDM

—In order to evaluate the throughput performance of DCF about both ultra-rate and longtime delay wireless local area network (WLAN) based on Orthogonal Frequency Division Multiplexing (OFDM) modulation channel, this paper analyzes the operating principle of DCF and the throughput of system on the basis of two-dimensional Markov Model. Through theoretical analysis of the relationship among 802.11a/g throughput, the number of node and the length of data packet are acquired. Analysis, calculation and simulation are done on the influences of bit number of information carried by OFDM, free aslottime and time span of OFDM symbol on system throughput. Results of theoretical calculation and simulation testing explain that under the environment of high speed and high delay, throughput of DCF would decrease in which throughput of basic schema is generally higher than that of RTS/CTS. Furthermore, our results indicate that the longer aslotime and OFDM symbol have and the higher wireless physical channel rate is, the lower throughput of DCF is.