mc-cdma matlab simulation

Started by omhr81 October 15, 2007
Hi, i m trying to simulate mc-cdma BER performance using MATLAB and
since mc-cdma is composed of the integration of DS-CDMA and OFDM so my
first step was building an OFDM model which passes bits on to a
"pskmod" mapper and then to "ifft", and the reverse at the receiver side.

When integrating with DS-CDMA for multiusers i m facing the problem
that "pskmod" function only accepts positive values from 0-M and in
DS-CDMA when adding different spreaded codes we get some negative
values that cant be given to "pskmod" e.g. " -2 2 0 0 -2 2 -2 -2".

So, how can i pass the spreaded codes using "pskmod"? Any help or
suggestion will be appreciated.