OFDM using USRP

GNU Radio
1

Hello.

I’m trying to set up OFDM using TI USRP 2921. At start I wanted to use
16QAM as modulation, but OFDM Mod block has no options for sync. I
switched to OFDM Tansmitter and choose QPSK. I have to main problems:

  1. I can’t set FFT len > ~300. It would be nice to set it at about 512
    or higher.

  2. Synchronization. For 300 FFT I’m planning to use 20 pilot channels,
    but I have a problem with sync words. Is there any rule how to create
    them?