The existing multiplexing techniques, such as TDM, FDM, and CDM, use different time slots, different frequency bands, and orthogonal codes, respectively, to distinguish each user. In this paper, a multiplexing model based on wavelet packets is presented. This model employs another kind of orthogonality -- the waveform orthogonality. In this approach, the channels are assigned to different users based on the mutual orthogonality of wavelet packets. After a brief review of the properties of wavelet packets, we can see that multiplexing based on the wavelet packets is a generalized form of TDM and FDM and it can be easily realized by the multiresolution algorithm developed for wavelet packets. In the multiplexing techniques, synchronization is an important problem. In this paper, the interference and cross- talk due to non-perfect synchronization between the receiver and transmitter are analyzed. It is demonstrated that with a suitable wavelet function, digital signals can be well recovered under noisy environments even when the synchronization is not accurate. The analysis on the synchronization also leads to the design of optimum wavelets for the application. Simulation results are presented and compared for the use of different wavelets.