Performance comparison of MQAM OFDM based WLAN System in presence of bluetooth interference with AWGN and rayleigh fading channel

Wireless local area networks (WLAN) operating in 2.4 GHZ ISM band are often subjected to interference from narrowband signal like Bluetooth, Zigbee etc. A system designer should consider the interference effect on WLAN for getting the best performance. Bit error rate (BER) of BPSK-OFDM based WLAN in presence of Bluetooth (BT) interference using rectangular BT spectrum is given in some previous work. But it is seen actual BT spectrum is non rectangular. So when Bluetooth's interference power will be high with respect to WLAN's power BER or symbol error rate (SER) of WLAN obtained using rectangular BT spectrum will not match with actual values of BER or SER in presence of Bluetooth interference. The reason is leakage effect in other sub carriers with respect to the sub carriers where Bluetooth has actually hopped is not considered in case of rectangular BT spectrum. In this paper we propose a interference model to find the power of Bluetooth (BT) interference for each sub-carrier of an OFDM based WLAN. Then using sub carrier power to interference power ratio symbol error rate (SER) for each WLAN sub-carrier is obtained in AWGN and Rayleigh fading channel. Finally average SER for the MQAM-OFDM based WLAN in presence of Bluetooth interference is given. Comparisons of BER or SER using the proposed model with the model of rectangular BT spectrum are given.. From the results it is seen that SER or BER curves using proposed model is closely matching with the actual SER or BER curves.