GPRS speeds

[andreasrothe]

If I use my GPRS-capable cellphone as a USB modem on my laptop, it tells me it connects at 230.4 kbps. But my NetActivity diagram tells me it runs at a max of 8kb. And judging by the transfer speeds, it seems more like 8kb than 230kb. Which one is correct? And why would the GPRS transfer so slowly (latency?)?

If I use my built-in dial-up modem connected to a Telkom landline, it tells me 44 to 52 kbps. And the transfer is significantly faster than the GPRS "modem". Why this?

 

[Jonny Two Shoes]

When it says it connects at 230.4 Kbps thats Kilobits not Kilobytes. Kilobits and kilobytes are different. So in actual fact your download rate will be much much lower.

GPRS speeds are around 70-100 Kbps (Kilobits) even though I can push my GPRS connection up to 980 Kbps in Windows it actually still sticks at around 80Kbps. That will give you roughly 8 - 10 Kilobytes or KB of transfer or download. Usually you can divide the number of Kilobits by 10 to get a rough quick estimate of Kilobytes but thats not by any means accurate.

I have heard newer GPRS cellphones are capable of slightly better GPRS speeds due to newer GPRS technology and compression etc.

Hope that answered your question

Oh yes and GPRS latency averages in general around 1000milliseconds or more meaning it takes at least a full second for your input on the net to reach the server and then back to you resulting in the lag you experience on GPRS. But latency and transfer speed are two different concepts and don't usually correspond with one another. You can have really good transfer rates but poor latency, like for instance a satellite link. Or you can have the best of both like better quality ADSL or even WiMax or so I hear.

 

[JazzeD]

Usually you can divide the number of Kilobits by 10 to get a rough quick estimate of Kilobytes but thats not by any means accurate.

Divide by 8 and that is accurate.


The speed u see on the connection is the speed of the USB connection to the phone and not the GPRS connection to the network.

 

[Jonny Two Shoes]

Divide by 8 and that is accurate.


The speed u see on the connection is the speed of the USB connection to the phone and not the GPRS connection to the network.

I had that nagging thought it was something like 8 rather than 10 thanks for clearing that up but Im rather stupid because its bits and bytes we are talking about which makes perfect sense with 8. Blonde moment

 

[Johnit]

8 bits make one byte, but the divide by 8 is not that accurate; there is an overhead on parity and or stop bits etc, so divide by 10 is not so far off.

 

[Jonny Two Shoes]

Ok Johnit don't confuse the issue!!!!!!!!!!!! You are just complicating matters!! Now Im never going to remember LOL

 

[andreasrothe]

Thanks all - much clearer.