Performance of Multi-antenna Array Assisted MC DS-CDMA Using Downlink Preprocessing Based on Singular Value Decomposition

In this contribution we propose and investigate a transmitter preprocessing scheme for downlink transmission in the multicarrier direct-sequence code-division multiple-access (MC DS-CDMA) systems using multiple base-station antenna arrays and each antenna array using multiple array elements. The transmitter preprocessing scheme is derived based on the singular value decomposition (SVD) approach. Our transmitter preprocessing design motives to support a high number of users by the MC DS-CDMA, to achieve the highest achievable diversity gain and to result in low-complexity detection for the remote mobilestations (MS’s). In this contribution the characteristics of the MC DSCDMA using the proposed transmitter preprocessing is discussed and the bit-error-rate (BER) performance is investigated, when assuming that each subcarrier experiences flat Rayleigh fading. Our study and simulation results show that, for a SVD-assisted MC DS-CDMA system using M transmit antenna arrays and the time (T)-domain spreading sequences of length Ne, the number of users supportable can be as high as MNe contributed by both the T-domain and S-domain. Furthermore, the SVD-assisted MC DS-CDMA system is capable of supporting such a high number of users with near single-user BER performance achieved by a corresponding MC DS-CDMA system supporting only one downlink user.