A Near-Far Resistant Precoding Technique for DS-CDMA Systems

A novel scheme is presented that enhances the near-far resistance of conventional transmitter precoding for CDMA with unequal power distribution. The proposed technique applies a partial pre-decorrelation to the users in contrast to the full orthogonalisation performed in conventional precoding. When the appropriate criteria are employed for the selection of the users to be decorrelated, an improved signal to interference-plus-noise ratio (SINR) is obtained without the need for additional power-per-user investment. Performance enhancement is attained for a variety of communication scenarios, but the focus of this paper is on unequal power users systems and the resistance to the near-far effect. Comparative simulations to conventional precoding methods demonstrate the superiority of the proposed technique.