Skype has more lag on 3G than 2G
 

Hey guys,
I was wondering if you guys notice that Skype (voice) is better on 2G than 3G. I was speaking to a friend in Korea using T-Mobile 2G and it was clearer than speaking to a friend in Pennsylvania using 3G. Both friends have broadband in their respective locations. I also tried to 3G Skype call a friend in South Africa and it was pretty bad. I've done regular Skype from my laptop to all 3 of these before and its never an issue. I tether from my laptop so its the same connection.

Anyone else having 3G Skype calls that have more lag than when using 2G?

Re: Skype has more lag on 3G than 2G
 

i dont think you are supposed to talk on skype with 2G network. it's not fast enough. i think by saying 2G you meant WIFI? otherwise it just beats me. if that's the case, normally wifi would bt better than 3G networks cuz the bandwidth's bigger

Re: Skype has more lag on 3G than 2G
 

isnt latency the important issue here? and not necessairly bandwidth?

Re: Skype has more lag on 3G than 2G
 

i think the limited bandwidth is the reason that caused the latency.

Re: Skype has more lag on 3G than 2G
 

No, that's precisely my point I have a more consistent experience using 2G. I have no wifi network at home. 3G should be better but it is not. Strange...

Re: Skype has more lag on 3G than 2G
 

according to speedtest.net:

3G: 136ms latency, 4.94 down / 1.18 up
2G: 342ms ping 0.19 down / 0.12 up

Skype calls on 3G should be fine but its not for some reason. Using Tunewiki I can only stream music on 3G which makes sense. What's up with Skype?

Re: Skype has more lag on 3G than 2G
 

Only thing that springs to mind is that maybe your operator is somehow limiting Skype-specific traffic. Don't know why the experience would be better with 2G connection though, maybe they're limiting it only on 3G connections(?)

Re: Skype has more lag on 3G than 2G
 

T-Mobile doesn't seem to care. Plus I tether from my laptop and it works fine there so I don't think they're limiting it at all.

Re: Skype has more lag on 3G than 2G
 

Wild guess: on 3G, you have more bandwidth available, so skype chooses a higher bitrate, and you use more CPU on the transmission/reception side -- system becomes CPU-bound and laggy.

On 2G, it scales back to a lower bitrate, which takes less CPU cycles to send, and it becomes I/O bound and behaves "properly".

With Skype on the laptop (and thus no codec processing on N900), the N900 is I/O bound for both cases, and of course the laptop always is, so "proper" behavior throughout.

Ways to test this hypothesis: use top or similar to monitor CPU load in both cases, with the aid of echo123. Or just overclock and see if it improves 3G but not 2G; if so, you might then consider overclocking on a regular basis, at least when using Skype. (Overclock at your own risk of accelerated hardware aging and death, naturally...)

Re: Skype has more lag on 3G than 2G
 

I think Benson is correct

skype is choosing a higher bandwidth codec on 3g that is causing problems(bandwidth isnt really high enough or cpu isn't up to it)

Re: Skype has more lag on 3G than 2G
 

Hey Benson,
That's what I thought too so I set my limits at 1100 1100. I normally do 250 900. At 1.1GHz it didn't make any difference.

I figure if my phone lasts more than 2 years I'm not using it at its full potential. ;-)

What's odd is that on 3G I feel like I'm half-duplex vs full-duplex with 2G. I know that the N900 sometimes can't walk and chew gum but in this case everything's backwards.

Re: Skype has more lag on 3G than 2G
 

Apple inspired theory:

You have pretty weak 3g signal (less than full bars), but strong 2g. When tethering you aren't holding your N900. When not tethering and talking on the N900, you're holding the N900 near the right (or bottom in portrait), dampening the 3g signal making it choppy.

Re: Skype has more lag on 3G than 2G
 

I think the N900's antenna is in the upper left though (near the webcam).

Re: Skype has more lag on 3G than 2G
 

Cellular antenna is near headphone port and the standby/keylock button.
Bluetooth and wlan antenna is near power button.
GPS antenna is near the webcam.

Source: User Guide -> Introduction -> About your device -> Antenna locations

Then the related link to making a call goes on to inconsitently show a picture of a person holding the device in the lower part where the antenna is.. Or maybe the picture is supposed to show that the thumb and finger is gripping the sides of the phone and that the palm is clear of the phone.

Re: Skype has more lag on 3G than 2G
 

It could be but I think in fact that I get actually really good 3G signals. I normally use my headphones so I know that holding the N900 is not an issue. I find that with headphones there is slightly more lag than without so in the end I end up holding it up to my ear.

For whatever reason I feel like the microphone / noise cancelling (if there is any) has timing issues with the headset and speakerphone.

It's a good theory but in practice holding the phone to my ear I get the best performance.