3G uplink interfernce

[islam wagih]

Dear Experts,
why uplink interfernce in 3G is more severe than DL interference?

[timedomain]

Dear,
UE has less output power compared to nodeb and think about the number of UE vs. nodeb's.. Less power level always prone to be interfered

[tharinduwije]

UL is weaker in power & compared to DL.So the UL noise floor should be lower for the Node B to distinguish between the UE signal & Noise

[Nyquist]

Hi. I would say that UL is more interference impacted because of orthogonal codes in UL are not correlated 100%. The more lack of correlation in codes the more interference. This is not the same in DL where correlation is close to 100%. Bear in mind that, even if UE has less power, the DL and UL link budget has to be balanced.
This is my view.

[islam wagih]

Hi. I would say that UL is more interference impacted because of orthogonal codes in UL are not correlated 100%. The more lack of correlation in codes the more interference. This is not the same in DL where correlation is close to 100%. Bear in mind that, even if UE has less power, the DL and UL link budget has to be balanced.
This is my view.

I want to ask why orthogonality will be different in DL & UL while the same are used.

[auto_art]

I want to ask why orthogonality will be different in DL & UL while the same are used.

reason for this is as Nyquist already said UL SC codes are no as good in orthogonality as Downlink.

ok, see in this way.

for downlink, if you are at a point X in the field we usually see 3 or 4 cells it's easier to extract useful signal for the UE receiver because all 512 have 0 cross-correlations.

in uplink, look from nodeB receiver side it hears from 100's of UE's at the same time and the SC they use doesn't have 0 cross-correlation. that is why we say WCDMA us UL limited.