High efficiency voice activated CDMA mobile communication system based on master code synchronization

The authors propose an innovative code division multiple access (CDMA)-based mobile system for voice (and data) services. The system makes use of voice activation in order to increase the CDMA efficiency (useful transmitted information vs. occupied bandwidth). The synchronization problems are solved by distributing a master code in the forward link and using forced link activation in the return when no speech activity is detected. The blocking probability is minimized by means of multirate speech coding associated with a centralized network control. Bit error rate calculations show all the advantages of operating in a synchronous mode.<>