A NEW TECHNIQUE TO ENHANCE SPREAD SPECTRUM COMMUNICATIONS

A NEW AND INNOVATIVE TECHNIQUE IS PROPOSED FOR USE IN THE RECEPTION OF SPREAD SPECTRUM CODE DIVISION MULTIPLE ACCESS (CDMA) SIGNALS. THE TECHNIQUE ALLOWS MUCH GREATER SEPARABILITY OF THE SIGNALS THAN THE CONVENTIONAL DEMODULATION APPROACH, THEREBY OVERCOMING THE USUAL NEAR-FAR INTERFERENCE PROBLEM ASSOCIATED WITH CDMA SYSTEMS. THE PROPOSAL IS FOCUSED ON A SONOBUOY TRANSMISSION SCENARIO IN WHICH THE AMOUNT OF BANDWIDTH EXPANSION IS LIMITED TO 1:100 (20 DB), AND WHERE DEMODULATION OF EACH WEAK CDMA SIGNAL REQUIRES MORE THAN 20 DB REJECTION OF STRONG COCHANNEL SIGNALS. REQUIRING ONLY A SINGLE RECEIVE ANTENNA, THE NEW TECHNIQUE INCLUDES THE AJ CAPABILITY TO REJECT OTHER COCHANNEL INTERFERENCES HAVING A VARIETY OF WAVEFORM TYPES. THE TECHNIQUE CAN BE READILY IMPLEMENTED WITH AVAILABLE DIGITAL COMPONENTS. A COMPUTER SIMULATION IS PROPOSED TO DEMONSTRATE THE FEASIBILITY AND PERFORMANCE OF THIS TECHNIQUE.