How to introduce OFDMA into ns-2

Hello,

I try to simulate an Ad-Hoc network on NS2. First of all, I try to introduce a
OFDMA into NS2.

OFDMA provides multiplexing operation of data streams from multiple users onto the downlink sub-channels and uplink multiple access by means of uplink sub-channels.

In OFDMA, both time and/or frequency resources are used to seperate the multiple user signals. Il allows for partitioning the time and frequency resources into :

OFDM symbols, s=1,…,S (in time dimension)

OFDM subcarriers, n=1,…N (in frequncy dimension)

Each user is allocated a number of OFDM symbols and subcarriers exclusively.

I don’t know how to start ??? I try to find solutions of allocation of different
subcarriers to different user.

I’m searching an implementation of OFDMA in C++

And other methods such as OFDM-FDMA or OFDM-CDMA, it’s possible.

Please help me.

Thank you at all in advance.