search

srsran / srsRAN_4G

Open source SDR 4G software suite from Software Radio Systems (SRS) https://docs.srsran.com/projects/4g
https://www.srsran.com
GNU Affero General Public License v3.0
3.48k stars 1.15k forks source link

Multiple Cells on Single USRP #1086

Open jeschr18 opened 1 year ago

jeschr18 commented 1 year ago

Issue Description

I am trying to run multiple eNB operating at different frequencies using a USRP B210 with two channels. Utilizing the configuration detailed in the Carrier Aggregation page on the srsRAN documentation, I was able to configure the software to set up two cells operating at separate frequency. However, when utilizing a spectrum analyzer, only one of the signals is found.

Setup Details

srsRAN 22.04 with a USRP B210 radio. enb.conf file modified to support multiple cells using the configuration provided by the Carrier Aggregation page in the documentation.

Expected Behavior

Two eNB operating at separate frequencies on USRP B210 Channels RF0 and RF1

Actual Behaviour

The RF1 channel operates as expected. The RF0 channel appears to set up properly on the software side of things, but does not transmit a signal (at least not at the desired frequency).

Steps to reproduce the problem

Default configuration files on the UE/EPC end (earfcn's changed on UE to support operation at different frequency). enb.conf is modified to support multiple cells and earfcn is changed on both cells to operate on different frequency.

matth3wh commented 2 days ago

I think that your problem is that the USRP B210 does not have independent oscillators for each channel. Therefore, when the second channel (RF1) starts up, the one common oscillator in the B210 goes that that new frequency. So your RF0 channel is also at the same frequency as you RF1, something I bet you could verify with a spectrum analyzer.