A sequency multiplexing technique for mobile communication systems

In this paper a multiplexing technique based on Walsh functions (sequency multiplexing) is described for the mobile spread spectrum multiple-access (SSMA) communication system. At the base station, the bit streams forwarded to each of 2K users are partitioned into two branches. In each branch it is first multiplexed by the corresponding Walsh function identifying a user and then it is spread by a PN sequence identifying one of two orthogonal components of the carrier of the branches. This multiplexing method makes all spread spectrum channels orthogonal and perfectly separated in the ideal case (provided perfect synchronization is achieved) at the same path, so it decreases the multiple access interferences. It is shown that sequency multiplexing combined with the spread spectrum technique is a suitable method for use on the down link of CDMA mobile communication system