Research And Implementation Of The CCK Modulation And Demodulation Algorithm Based On FPGA

Wireless Local Area Network (WLAN) has the characteristic of both radio communication and computer network. WLAN has become an important part of personal communication, provides the demand of people with wideband wireless network anytime and anywhere, and will have widespread application in the reality and future of social life. The establishment of the IEEE802.11b standard is the milestone of WLAN. The IEEE802.11b standard has become one of the current mainstream WLAN standards, and the products according to this standard occupy a large market share.This thesis puts great emphasis on the principle of CCK (complementary code keying) and the key algorithm-FWB-in the demodulating process. Being the key modulation technology in the IEEE802.11b standard, the CCK code has an excellent correlation characteristic. So the products according to this technology could not only transmit high-speed data but also overcome the multipart effects effectively. Beginning with a briefly introduction of the structure and characteristics of WLAN, the thesis researches the IEEE802.11b standard, especially the structure and specification of the physical layer in base band. Then this thesis describes the characteristics of the CCK code in detail. The modified FW (fast Walsh) algorithm is introduced for the communication with data rate of 11Mbps. The modified FW, together with a bi-stage correlation calculation process using fast Walsh block, significantly reduces the computational complexity and hardware consumption. Moreover, by means of simulating the design scheme of the modulation and demodulation in Matlab, correct theoretical data are obtained and the feasibility of the scheme is confirmed.Finally, the demodulation systems are designed and programmed in hardware description language Verilog in FPGA, and then functional simulation of the whole system is carried out in ModelSim, the actually circuit board is designed and developed.