Need to build eCPRI link in xRAN network between eRE and eREC devices.

In eRE I'm capturing via osmocom source (SDR device) and I have a stream of float32 complex IQ numbers as usual output. Now I am building GRC module that will craft eCPRI packet and output it to GRC's UDP sink to send them to eREC via ETH wire.

Now as far as I understand eCPRI v1.2 spec, all PHY decoding will be done on eREC side, so I just need to capture IQ data and put them in proper format which is eCPRI (msg type = 0x02). This is my User-Plane.

However, eCPRI packet needs (optionally?) OFDM symbols as well and other Real-Time Control data for example, how can I get them?

Can't find an example of GRC diagram for eCPRI.

  • $\begingroup$ I don't think such a thing exist. It also makes little sense: while you should probably write a GNU Radio sink to build your ethernet frame, all eCPRI does for you is transport the samples, so you can put in whatever baseband signal you like. There's no such thing as a GRC flowgraph specifically for eCPRI. $\endgroup$ Apr 30, 2022 at 12:53
  • $\begingroup$ @MarcusMüller, but if I have let's say, 796MHz signal, I need to do in GRC following: osmocom source -> Freq offset calculation -> OFDM demod -> Channel Estimation -> stream/vector -> eCPRI packet (where we have OFDM symbols), right? Signal is noisy and I need to handle it properly before putting samples to eCPRI packet, right? $\endgroup$ Apr 30, 2022 at 16:55
  • $\begingroup$ I'm not versed enough with eCPRI, but what you describe, and what I would expect, is that eCPRI packets just contain time-domain samples, $\endgroup$ Apr 30, 2022 at 19:08
  • $\begingroup$ @MarcusMüller, ok, to clarify what I've understood so far: in eRE device, we just pass freq data (IQ) to eCPRI and time data to sync via PTP protocol to ETH, where on eREC we do all decoding. Freq domain: osmocom source --- stream of float32 IQ ---> Python custom block to craft eCPRI ---> UDP --> ETH Time domain: Some clock sync(?) --- PTP protocol --> ETH $\endgroup$ May 1, 2022 at 18:43


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