Abstract: Based on NS2-MyEvalvid, an analysis was conducted on the effect of quantization factors upon the performance of image transmission in this paper. And by simulation, the successful transmission of the video streams grounded on Evalvid mechanism in Wireless Local Area Networks (WLAN) was achieved. A summary of the method to simulate the image transmission process of video streams in WLAN by encoding the related parameters was also provided. Furthermore, by means of changing the encoded quantization factors, the average data of the delay of image and PSNR during the transmission of video streams in multirate WLAN was got, together with a conclusion that 802.11e will guarantee a better transmission performance of video streams than 802. 11b.

Key words: Evalvid, Quanti}ation factors, NS2, 802. 11b, 802. 11e, Quality of Scrvice, Multimedia