[Discuss-gnuradio] Questions on OFDM transmission on USRP2

[rick rick]

Hi

I have some questions and observation on OFDM based transceiver.

I adopted the modified code provided by Veljko Pejovic (link: www.cs.ucsb.edu/~veljko/downloads/ofdm_example.tar.gz). After trying different combinations of parameters, I managed to get benchmark to work with most package received correctly. However, it turned out the CPU usage was very high, almost 90% for receiver. Here is the specs: USRP2, WBX, Ubuntu 10.04, GNU radio 3.3, Intel core 2 duo 2.66GHz, ram 2G. Can anyone share the insight why the OFDM receiver is so computationally intensive? (-f 434M fft-length=128, occupied-tones=80, -d/-i 32, cp-length=32.)

In addition, I also tried to build a new tunnel.py based on the revised OFDM codes. I got continuous Timeout (received preamble but not the entire data frame) and SSS... (missing packets), evenif only one USRP was turned on. However, supposedly it should not receive any signals. Does anyone successfully build an OFDM based tunnel?

An