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. In this paper, we demonstrate how an 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.