ADAPTIVE RATE MODEM FOR MOBILE CELLULAR CODE DIVISION MULTIPLE ACCESS CHANNELS

THE UNITED STATES IS CONVERTING ITS ANALOG CELLULAR TELEPHONE NETWORK TO DIGITAL. THE DRIVING FORCE BEHIND THIS CONVERSION IS THE NEED FOR GREATER CAPACITY. CELLULAR SYSTEMS IN MOST LARGE CITIES ARE FULL AND BLOCKING PROBABILITIES ARE UNACCEPTABLY HIGH DURING BUSY HOURS. DIGITAL CELLULAR WILL INCREASE THE CAPACITY OF EXISTING SYSTEMS BY BETWEEN 4 AND 10 TIMES WITHOUT THE NEED FOR ADDITIONAL RADIO SPECTRUM. THE PURPOSE OF THIS STUDY IS TO INVESTIGATE A NEW ADAPTIVE TECHNIQUE FOR CODE DIVISION MULTIPLE ACCESS (CDMA) CHANNELS THAT WILL FURTHER INCREASE DIGITAL CELLULAR CAPACITY. THE TECHNIQUE AUTOMATICALLY AND DYNAMICALLY ADJUSTS EACH USER'S DATA RATE TO THE INSTANTANEOUS FADING AND INTERFERENCE CONDITIONS OF THE CDMA CHANNEL. THE OBJECTIVES ARE TO MODEL THE CHANNEL, SIMULATE THE TECHNIQUE, AND DEMONSTRATE PERFORMANCE IMPROVEMENTS IN THROUGHPUT AND BLOCKING PROBABILITY. THROUGHPUT IMPROVEMENTS OF A FACTOR OF 5 AND REDUCTIONS IN BLOCKING PROBABILITY OF A FACTOR OF 4 WILL BE DEMONSTRATED. POTENTIAL APPLICATIONS OF THIS RESEARCH INCLUDE DIGITAL CELLULAR, WIRELESS LOCAL AREA NETWORKS (LANS), MICROWAVE RADIO, AND HIGH FREQUENCY (HF) RADIO. THIS RESEARCH WILL CONTRIBUTE TO THE UNITED STATES' TECHNICAL COMPETITIVENESS IN WIRELESS COMMUNICATIONS WHERE OUR PRINCIPAL COMPETITORS ARE JAPAN AND SWEDEN.