Adaptive data transmission based on band-selection for MC-CDMA systems

We introduce an adaptive band-selection (ABS) scheme for Multi Carrier-Code Division Multiple Access (MC-CDMA) systems to improve system capacity. Instead of using all subcarriers, mobile stations transmit message data only through the selected frequency bands based on band-selection coefficients from the base station. By using the adaptive band-selection scheme, ABS MC-CDMA systems accommodate more users than MC-CDMA systems that use all frequency bands for message data transmission. Due to the time-varying wireless channel conditions and dynamic power allocations, band-selection coefficients should be adaptively determined at the base station every update period. In our ABS MC-CDMA systems, the processing gain, the transmitted power and the data rate depend on the number of selected bands. Under the assumption that the total transmission power and the total amount of transmission data are the same for both MC-CDMA systems and ABS MC-CDMA systems, SNR behaviors are investigated and BER performances are presented in terms of the number of users and the normalized Doppler frequencies