Improvement on bit-error-rate performance of DS-CDMA by employing 4-elliptical phase shift keying

Some modulation schemes with the general name of Elliptical Modulation Schemes, have been proposed and evaluated, in terms of Bit-Error-Rate (BER) performance, namely are Eccentricity Shift Keying (ESK), Inclination Angle Shift Keying (IASK), Rotation Frequency Shift Keying (RFSK) and Elliptical Phase Shift Keying (EPSK). Based on their advantages over existing modulation schemes, this paper aimed to confirm the contributions of 4-EPSK, one of Elliptical Modulation Schemes with 2-bit information transmission capability, to the improvement of CDMA communication systems. In the paper, we investigated the possible applications of 4-EPSK to CDMA systems, through evaluating BER performance of synchronous DS-CDMA by employing 4-EPSK as its modulation scheme, with an M-sequence and an orthogonal Gold sequence respectively, along with comparison to that of DS-CDMA by employing QPSK; simulation results have been achieved based on changeable number of users, under AWGN and flat Rayleigh fading environment respectively. Advantages of DS-CDMA-4-EPSK over existing DS-CDMA-QPSK achieved in simulations, implies that by employing 4-EPSK as its modulation scheme, CDMA systems can be improved in terms of BER performance.