Novel orthogonal codes for MC-CDMA with low crosscorrelation in frequency selective fading channels

Typically, Hadamard-Walsh (HW) codes are employed as spreading codes in MC-CDMA to maintain the orthogonality between different users. However, after transmission through frequency selective fading channels, the orthogonality is lost and MAI is observed at the MC-CDMA receiver. We demonstrate how novel complex spreading codes known as carrier interferometry codes achieve lower crosscorrelations than Hadamard-Walsh codes after transmission over a frequency selective channel. This lower crosscorrelation property leads to higher SIR at the MC-CDMA receiver, and, as a direct result, better performances in term of probability-of-error are observed.