Performance analysis of frequency diversity for multi-carrier CDMA system based on bridge function

Based on the characteristics of Bridge function, i.e. zero and nonzero distribution, bridge function's spreading spectrum feature was analyzed and concluded that it is a kind of discrete spreading mode. In specific channel environment, if coherent bandwidth and single sub-carrier bandwidth is known, we can choose the shift parameters for bridge function sequence to get the best frequency diversity. At the same time, the cochannel interference is decreased and the system channel capacity is improved. On the basis of discussing the difference between bridge function's discrete spreading and traditional discrete spreading, the traditional discrete spreading mode is modified and extended. The new spread spectrum mode will be more flexible and can be adapted to the complex variable channel. And the better frequency diversity can be achieved with various channel environments. The simulation results verified the superiority of bridge function in the MC-CDMA system.