Impact of multipath fading and partial-band interference on the performance of a COFDM/CDMA modulation scheme for robust wireless communications

The performance of a COFDM/CDMA radio communication system in the presence of partial-band jamming is presented where the effects of multipath and additive noise are included. The importance of interleaving and coding is emphasised and their impact on the bit error-rate performance is evaluated. In the first part of the paper, the effect of jamming on a COFDM system is obtained under worst-case conditions. For single tone jamming, the results show that the effect of the jamming signal on the bit error rate is acceptable, even at signal to jamming power ratios as low as -15 dB, when interleaving and convolutional coding is used. For the case where 20% of the transmission spectrum is corrupted by partial-band jamming, it is necessary for the signal to jamming power ratio to be 5 dB or more to achieve an acceptable bit error rate. To provide additional resilience, the case of an OFDM/CDMA scheme is examined where the spread-spectrum process gain is used to provide additional protection against jamming