The Study And Design Of Wireless Access Point

With the development of wireless technology and the decrease of the produce cost, wireless local area network attracts more attention by its convenient installation, flexible operation, low cost and removable character. Wireless access point is an important equipment to build the wlan. It connects the removable host with Internet or other network, and transmits the frames between wlan and the cable network.The price of AP is much higher than wireless card and some AP replacing plan is complicated. It becomes a big problem on how to decrease the cost, make full use of existing embedded equipments and enhance the performance of wireless card. Based on the researches of IEEE802.11b, the device drivers of uClinux and Prism 3.0 chip group, this thesis implements the wireless card driver with USB interface in uClinux and develops Host AP driver. With these drivers, wireless card can easily switch between "Station mode" and "Soft AP mode". As a result, the embedded equipment with USB and network port can be configured not only to connect to network by wireless card, but also to work as AP.The basic function of Soft AP implemented in the thesis doesn't have many differences with traditional AP. Although the access capability and the coverage area of Soft AP can't reach the standard of AP, it has certain advantages on many occasions. For example, users only need to install AP drivers on the existing embedded equipment, and then they can enjoy the function of AP, which is much cheaper. Another advantage is that it is convenient for the developers to add new functions because most of the 802.lib's functions are controlled by the host's CPU. The user can improve AP's performance or add management functions according to certain requirements. Nowadays, new standards of wireless network emerge continuously. It becomes much easy to update the standards by using the Soft AP designed in the thesis. The only thing need to do is to change the wireless card and corresponding driver. This Soft AP can provide an economic and convenient way to connect a few users in local area. It is extremely flexible when constructing a temper local network.This thesis analyzes the standard of IEEE 802.11, discusses the different ways of realizing AP, and then defines the basic function of AP, gives the design of hardware platform and system structure. Then it discusses the implementation of wireless card driver based on Prism 3.0 chip group and describes the design of the AP function in...