Design & Research For Wireless Network Card Based On Direct Sequence Spread Spectrum

With the coming of information era, the wireless local area network is developing very fast, the design of WLAN products gain the attention of people inland or outland.The wireless network card is the key hardware of WLAN. The computer installed network card can share the resources of WLAN. To a certain extent, the performance of network card impacts the capacity of WLAN.WLAN has several standards, of which the IEEE802.11 is the earliest one and is most widely used now. In chapter 1 and 2 the author describes the characters of WLAN and the components of the IEEE802.11 architecture. Some key technologies to form IEEE802.11 and the frame of signal transferred in each WLAN layer are also depicted. The standard and technical guideline of physical layer (PHY) are emphasized.A blue print of designing a wireless network card is introduced in chapter 3, in which the PRISM II chipset made in intersil co. is adopted. In detail, the author narrates the function and working elements of network card, and the signal processing from baseband to IF to RF, also the protocol process of medium access control (MAC) layer.In chapter 4 and 5, a PHY communications processor based on direct sequence spread spectrum (DSSS), that is, the T/R signal processor part in a network card, is designed and realized, which is basically compromise the IEEE802.11 standard. It exchanges data and control information with computer through the serial port-RS232. The main working finished are as follows:1. Compile a person/computer interface, that is, the serial communications program in Windows environment with Visual C++.2. The micro-computer and the field programmable gate array(FPGA) realize the control part of this T/R signal processor appealing the high speed transfer request, and the transform of communication protocol between MCU and this signal processor.3. The data transfer part of this signal processor includes the modulating or demodulating from baseband to IF to RF. Accordingly, the DSSS baseband pro-cessor-HFA3861B, the I/Q Modulator/Demodulator-HFA3783, the RF/IF con-verter-HFA3683A are applied.