Spreading code detection and blind interference cancellation for DS/CDMA downlink

We propose a new blind interference scheme algorithm suitable for the direct-sequence code-division multiple access (DS/CDMA) downlink. The interferer codes are unknown but the family to which they belong is supposed to be known. The proposed technique is blind in the sense that only the desired user´s spreading code is assumed to be known a priori. The remaining parameters required for the interference cancellation such as spreading codes and energies of interfering users are estimated using subspace decomposition and projection on the family of codes. Fast and efficient implementations are discussed. Therefore, unlike standard interference cancellers which can be used only in the uplink, the proposed method can be implemented at the mobile terminal.