FTTC Noise Margin for Upstream

Quick question if i may. Is the SNR lowered in 1db steps (where applicable) on Huawei cabs for upstream or is this only applicable to the downstream?

In reply to a post by gary333:

Quick question if i may. Is the SNR lowered in 1db steps (where applicable) on Huawei cabs for upstream or is this only applicable to the downstream?

The upstream SNRM target is always 6dB on both Huawei and ECI cabinets.

The current SNRM can be lower, particularly after a resync, but the target remains 6dB.

Cheers John. Do you know if this is because lowering the noise margin wouldn’t make much difference / some other technical reason or is it just not seen as important by providers?

You can only have a sub 6dB (5, 4 and 3dB) SNRM if G.INP is enabled.

My guess would be that OpenReach don't provide the option of a lower SNRM on the upstream because G.INP isn't automatically applied to the upstream the same as it is to the downstream.

The lack of G.INP by default on the upstream is due to many modems only supporting G.INP on the downstream and issues with upstream G.INP on certain modems noticed during the original G.INP rollout.

Errors increase with a lower SNRM and G.INP does a great job dealing with said errors.

Edited by j0hn83 (Tue 21-Jul-20 04:12:52)

No, my FTTC always stay higher than 12dB on upstream SNR but always get 20000Kbps for six years.