A tiny issue for srsRAN_4G/lib/src/phy/ue /ue_sync_nr.c

[WanHaoRan]

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Issue Description

A small issue in the subframe counter.

Setup Details

I am writing some of my own codes on top of srsRAN_4G. I found that when I do the synchronization after cell search with a 5G SA TDD cell, there will be a whole system frame number jumping in the synchronization result. The problem might be caused by the srsran_ue_sync_nr_zerocopy function in srsRAN_4G/lib/src/phy/ue /ue_sync_nr.c.

Expected Behavior

Each synchronized system frame's and subframe's index increases linearly, starting from 0.

Actual Behaviour

The subframe's index starts from 1 and ends with 0. After one system frame, the synchronization process will skip the next system frame.

Additional Information

I moved the q->sf_idx++; to the end of the srsran_ue_sync_nr_zerocopy function, right above return SRSRAN_SUCCESS; to add after the subframe processing and it works as I expected. I am not sure if this is a bug or caused by the TDD base station. Please tell me if I understand it wrong. Thanks!