Hello, I am utilizing two USRPs, specifically the X300 models, along with GNURadio for the purpose of transmitting and receiving OFDM signals. I have implemented the OFDM flowgraphs available on Github for this purpose. The transmission and reception setup involves LOS (Line-of-Sight) configuration, where the transmit and receive antennas are positioned with a separation distance of 2 meters. To minimize the impact of multipath interference, the antennas are surrounded by absorption boards. Although the transmission and reception process itself is functioning without issues, I have encountered a problem when displaying the channel state information. In particular, there are instances where invalid packets are detected, as evidenced by the following occurrences. packet_headerparser_b :info: Detected an invalid packet at item 167472header_payload_demux :info: Parser returned #f I have searched the possible causes of the error I'm encountering, and there are a few factors that have been suggested:
1- Interference--> I used different frequencies and ensured they are not in use.2- Multipath --> absorption boards were used to minimize the impact of multipath.3- Some people suggested to change the FFT length and CRC length as a potential solution, however, modifying these papermeters did not resolve the issue. When I used a channel model instead of USRPs, the error did not occur. I am still uncertain about the exact cause of the error I am experiencing. Thanks, HZ
