Designing WLAN System with Adaptive Modulation and Coding over Dispersive Multipath Fading Channel

Abstract: In the past decade there has been a steady growth in development and implementation of Wireless Local Area Network and Remerged as in the largest sector of the telecommunication industry. Wireless Local Area Network (WLAN) provides connectivity, mobility, and much higher performance and achievable data rate. WLAN is a new medium of a access technology in the Local Area Network (LAN) world. Mostly WLAN applications are used in public sectors such as airports, banks, hotels, offices, city centres because of the flexibility of the people. Orthogonal Frequency Division Multiplexing (OFDM) has been adopted by IEEE 802.11’s standard as a transmission technique for high data rate in WLANs. Now IEEE 802.11 standard has been expanded to a family of WLAN standards. 802.11a and 802.11g both are used Orthogonal Frequency Division Multiplexing (OFDM) but operate in different frequency bands. It is shown that 802.11a provides high speed throughout the entire coverage area and long term solution however it does not provide better solution in most cases as compared to IEEE 802.11g. Matlab Simulation model of WLAN based on IEEE 802.11a using different modulation and demodulation techniques such as BPSK, QPSK and QAM to analysis the best performance of IEEE 802.11a with implementation of OFDM. Furthermore, the results show that the performance is improved significantly by adding convolutional coding with Viterbi decoding, and thus highlights the importance of Forward Error Correction (FEC) coding to the performance of wireless communications systems.

Keywords: WLAN, OFDM, BER, FEC.