TRELLIS CODING WITH CONTINUOUS PHASE MODULATION (CPM) FOR SATELLITE BASED LAND MOBILE COMMUNICATION

SATELLITE-BASED LAND MOBILE COMMUNICATION USING DIGITAL TECHNIQUES SUFFERS FROM POWER AND BANDWIDTH LIMITATIONS. THEREFORE THE NEED IS GROWING FOR THE DEVELOPMENT OF A BETTER POWER AND BANDWIDTH EFFICIENT CODING/MODULATION SCHEMES. THE PURPOSE OF THIS WORK IS TO DEVELOP AN OPTIMAL TRELLIS CODE COMBINED WITH POWER AND BANDWITH EFFICIENT MULTILEVEL CONTINUOUS PHASE MODULATION (CPM). THE COMBINED CODING/MODULATION SCHEME IS DESIGNED TO HAVE A RELATIVELY SMALL OUT OF BAND POWER IN ORDER TO MINIMIZE THE ADJACENT CHANNEL INTERFERENCE, ALLOWING TRANSMISSION OF 4800 BITS/SECOND THROUGH A 5 KHZ CHANNEL. THE SYSTEM WILL ALSO HAVE THE CAPABILITY OF HANDLING RICIAN FADING CHANNEL. FURTHERMORE, THE CPM IS A CONSTANT ENVELOPE MODULATION TECHNIQUE ALLOWING IT TO BE APPLICABLE FOR EFFICIENT HIGH POWER AMPLIFIER (HPA) IN TRANSMITTERS. IN PARTICULAR THIS WORK PLACES MORE EMPHASIS ON SHORT MEMORY ( 4) TRELLIS CODES WITH 8 LEVEL CPM AND SMALL MODULATION INDEX (H < .2). RECTANGULAR AND RAIDED COSINE PULSE SHAPES WITH DURATION ONEAND TWO SYMBOL TIMES WILL ALSO BE CONSIDERED.