Problem on passing complex data from rx_path to tx_path in benchmark_ofdm


I am currently implement such scheme that have to pass the
information(complex data type) from rx_path to tx_path in
The information (complex data) is said to be channel gain that can be
calculated by pilot sequence inserted in ofdm symbol, and it can be get
from And I want to make use of this information
next transmitted packet. So I need a method to implement this scheme.

Here are some methods that I used to implement but got some problems.

  1. In, I save the complex data in a file and
    read this file when I send a packet. But it seems that saving file will
    slows down the process and causes the packet fail.

  2. I rewrite the io_signature in the block of
    that increase the output port for the complex data. And connect this
    port to
    the transmit path.
    Like this:
    Rx-USRP → rx_path --(gr_complex)-- tx_path → Tx-USRP
    I know the rx_path and tx_path are parallel in GNU Radio. Is it possible
    connect these two block with one port?

  3. Maybe I can use gr_message. But I don’t know how to use it for the
    is complex data type. It seems that gr_message is for string data
    char). Can it use for complex or floating data type?

Anyone have any suggestions about these problems, please let me know.
I am deeply appreciative.


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