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Direct sequence CDMA employing combined modulation schemes

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2 Author(s)
Jun Wang ; Dept. of Electr. Eng., Ottawa Univ., Ont., Canada ; Yongacoglu, A.

In most direct sequence code division multiple access (DS-CDMA) systems, the modulation scheme used is a simple one. In this paper, employing a combined modulation scheme in DS-CDMA is proposed. By combining two or more modulation schemes, the resultant symbol energy can be increased, and thus a better symbol error rate performance can be achieved. For the combined modulation scheme, the symbol error rate is determined by the less powerful one of the basic modulation schemes. So a proper selection of modulation combination is essential for power efficiency. In a DS-CDMA system, unlike a narrow-band system, the bandwidth efficiency is closely related to its power efficiency. Thus a combined modulation concept may result in a bandwidth efficient DS-CDMA system. In this paper, we present two DS-CDMA schemes by combining MFSK and coherent MPSK and differential BPSK. These two schemes are respectively denoted as (1) MFSK-MPSK/DS-CDMA, and (2) MFSK-DPSK/DS-CDMA. The proposed schemes have better performance than the conventional CDMA schemes

Published in:

Global Telecommunications Conference, 1993, including a Communications Theory Mini-Conference. Technical Program Conference Record, IEEE in Houston. GLOBECOM '93., IEEE

Date of Conference:

29 Nov-2 Dec 1993