Three Dimensional Concatenated Codes in OFDM Transmission System under a Rayleigh Fading Channel with Carrier Interference

الملخص

Orthogonal frequency division multiplexing (OFDM) or multicarrier transmission has been shown to be an effective technique to combat multipath fading in wireless Communications. It has been successfully used for HF (High frequency) radio applications and has been chosen as the standard for digital audio broadcasting and digital terrestrial TV broadcasting in Europe and high-speed wireless local areas networks. This paper describes the concept behind parallel data transmission and the configuration of an OFDM transmitter and receiver system when 8DPSK is used (8ary-Differential phase shift keying) as a modulation technique with the effect of carrier interference. First, the BER (Bit Error Rate) is evaluated for the OFDM system in two typical channels, the AWGN channel and the Rayleigh fading channel when we used a guard interval of 25% of the symbol period compared with the theoretical channel performance for each channel. Second, the BER is evaluated for the OFDM system in a Rayleigh fading channel with the effect of carrier interference for two values of the carrier-to-interference ratio (CIR=15 dB & CIR=20 dB). In this case, some of the subcarriers are completely lost by deep fades due to multipath fading and carrier interference. So, Forward Error Correcting (FEC) code is used to improve the performance of the OFDM system with carrier interference...