QAM based adaptive modulation for OFDM-CDMA wireless networks

Orthogonal frequency division multiplexing (OFDM), which employs orthogonal overlapping sub-carriers to modulate the signals, has attracted much attention in recent time as a favorable option for future generation wireless networks due to its ability to overcome many wireless channel impairments. Since OFDM is a multicarrier system, adaptive modulation techniques can be effectively and efficiently used to enhance the system performance in terms of both BER and overall system capacity. The paper discusses an OFDM-CDMA system with adaptive modulation schemes for future generation wireless networks. The results presented show that adaptive systems can perform better than fixed modulation based systems both in terms of BER and spectral efficiency.