| With the wireless LAN standards IEEE802.11 series of successful development and continuous improvement , wireless LAN (WLAN) was applied to the growing field. It is growing demand for wireless transmission, data transmission volume is growing. l-2Mbps transmission rate has been unable to meet people's demands. IEEE802.11b protocol works in 2.4GHz and makes transmission rate to 5.5-11Mbps to meet the basic needs of general users. But it has a significant gap for cable network transmission rate. Although the protocol of IEEE802.11a make transmission rate to 54Mbps, but because of working in 5.8GHz and can not be compatible with 802.11b prodution , so it can not be effectively spread. Therefore single frequency and double mode wireless LAN is the key to solving this problem. Single frequency and double mode wireless LAN in this paper is work in 2.4GHz frequency, and support both DSSS and OFDM wireless LAN transmission model.DSSS is the key communication technique of IEEE802. 11b, also is one of the key communication technique in IEEE802.11g single band and dual mode WLAN. Therefore, this paper is mainly about the reaserch of DSSS communication technique. The primary work is:(1) Analysed 802.11b, 802.11a, 802.11b, 802.11g protocols, research the key technology for their respective .(2) Researched model of wireless channel and multipath ullage, introduce CCK technology. And carries on the simulation analysis(3) Researched realization and change of the data transmission speed, analyses the key technology, and carries on the simulation analysis.(4) Analyses that the wireless AP hardware of Broadcom chip is be adopted as the solution based on 802.11g, and then tests its practical capability.The results of the study showed that using DSSS technology on single band and dual mode WLAN can transmission data steadily in high E_b/N_o condition, using DSSS—CCK technology can increase transmission rate tollMbps, And using DSSS —PBCC technology can increase transmission rate to 22Mbps... |
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