WHAT IS ORTHOGONAL MULTI-CARRIER CDMA?
There are many equivalent ways to describe MC-CDMA:
1.MC-CDMA is a form of CDMA or spread spectrum, but we apply the spreading in the frequency domain (rather
than in the time domain as in Direct Sequence CDMA).
2.MC-CDMA is a form of Direct Sequence CDMA, but after spreading, a Fourier Transform (FFT) is performed.
3.MC-CDMA is a form of Orthogonal Frequency Division Multiplexing (OFDM), but we first apply an orthogonal
matrix operation to the user bits. Therefor, MC-CDMA is sometimes also called "CDMA-OFDM".
4.MC-CDMA is a form of Direct Sequence CDMA, but our code sequence is the Fourier Transform of a Walsh
5.MC-CDMA is a form of frequency diversity. Each bit is transmitted simultaneously (in parallel) on many different
subcarriers. Each subcarrier has a (constant) phase offset. The set of frequency offsets form a code to distinguish