How to split one usrp_received input stream into more output streams

Hi everyone,
Recently, I intend to write a signal process block,but a problem is
confused me. How to split one input stream into multiple output
streams.
Here is the problem with background in detail.
I plan to split my received signal into N frames, each frame will be
connected into fft_vcc, finally the N frame after FFT going to be
computed average value. So, I want to know how to split one input into N
output.
any help would be appreciate,
thank you