# OFDM link simulation **URL:** \ **Category:** GNU Radio\ **Created:** [March 19, 2014, 1:45am UTC](https://www.ruby-forum.com/t/ofdm-link-simulation/239899 "2014-03-19T01:45:33Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [March 19, 2014, 1:45am UTC](https://www.ruby-forum.com/t/ofdm-link-simulation/239899/1 "2014-03-19T01:45:33Z")
I want to simulate an OFDM link to carry 214 bytes per Ethernet packet & implement it using 2 laptops running GNU & 2 USRPs. Each USRP is a TX & RX .(FULL-DUPLEX) I calculated all OFDM parameters needed. total BW=200KHz sample Rate=240k symbol time including CP=5ms= 8-burst gsm ( one burst is 0.6ms) T guard= CP =625u T data=4.375ms 2 bits/subcarrier (QPSK) number of bits/ ofdm symbol =440 bits 256 subcarriers per symbol , 224 subcarriers used for data , 2 subcarriers for pilots. FFT size =256. I want to use constitutional coding. I don’t know how to start , and what to write in ofdm blocks (what to write in occupied carriers in ofdm transmitter for ex. , … ) I don’t know which blocks can be used & what to write in each field in the blocks. And how to apply constitutional code , do I have to use specific block?! I am new to Ubuntu & GNU. I found in GNU folders , Python and c++ codes , I don’t know if I have to change in any of these files? Do I have to read them to understand ? Do I have to write a code to make a TX/RX block ? (As I need full duplex link) Anyone can help me how to start?? As I installed GNU a month ago , I tried to read tutorials and search in doxygen , but till now , I am so confused & don’t know how to fill the fields in the blocks!! Thanks 🙂 ---
**Author:** ![Sara\_ChSSrif](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@Sara\_ChSSrif](https://www.ruby-forum.com/u/Sara_ChSSrif)\ **Post date:** [March 19, 2014, 3:12am UTC](https://www.ruby-forum.com/t/ofdm-link-simulation/239899/2 "2014-03-19T03:12:36Z")
Hi Sara, Please look at the OFDM TX/RX examples in GNU Radio Companion. It’s already there for you. 🙂 best, aditya