Multi-scale DS-CDMA for 4G wireless systems

We design a multi-scale DS-CDMA as a new multi-rate system using orthogonal optimum wavelets for 4G wireless systems. Multi-scales of chip waveforms that generates a multi-chip rate scenario provide orthogonality between users on the different scales and allows to use the same frequency bandwidth. The probability of error, and power spectral density (PSD) equations of this multi-chip rate system for quasi-synchronous case are derived. Then, optimum wavelets are obtained. This design provides better interference cancellation and bandwidth efficiency, compared to conventional multi-rate systems.