FAQ: Why is my GPRS, EDGE, or UMTS so slow?

Q: Why is my GPRS, EDGE, or UMTS so slow?

A1: SERIAL PORT BOTTLENECK: Connections between handsets and "tethered"
devices (e.g., notebook computer, PDA) are typically implemented as a serial
port, either real or virtual, and port speed usually defaults to 115 Kbps. (My
own Bluetooth stack is implemented as a virtual serial port that will go as
fast as 921.6 Kbps, but which runs at only 115.2 Kbps by default.) While 115
Kbps is generally fast enough for GPRS and CDMA 1X, it can be a bottleneck for
EDGE, UMTS, and CDMA EV-DO. In general, I recommend port speed* of 230 Kbps
for GPRS and CDMA 1X, 460 Kbps for EDGE, and 920 Kbps for UMTS and CMDA EV-DO.

A2: HANDSET CAPABILITIES: Handsets (and PC Cards) do not all have the same
data performance. In general, all reasonably recent GPRS/EDGE-capable devices
from Ericsson and Sony Ericsson support Class 8 (4+1) and Class 10 (4+2, max
of 5), whereas most Nokia devices are limited to slower Class 2 (2+1), Class 4
(3+1), and Class 6 (3+2, max 4). Motorola has both Class 4 and Class 8
devices. (The first number is the max downlink slots, and the number after the
"+" is the max uplink slots.) This can translate into a substantial difference
in throughput -- if supported by the carrier:
- Class 4 or Class 6 is 50% faster on downlink than Class 2
- Class 8 or Class 10 is 100% faster on downlink than Class 2,
33% faster on downlink than Class 4 or Class 6.
- Class 10 can be 100% faster on uplink than Class 2, Class 4, or Class 8.


* To set cellular serial port speed in Windows XP:
- Open Network Connections
- Right-click on cellular connection, and choose Properties
- In Properties-General, select checked cellular modem, and click Configure
- In Modem Configuration, select desired Maximum Speed.
- Click OK to close all windows.

---

› See More: FAQ: Why is my GPRS, EDGE, or UMTS so slow?

John Navas wrote:
> Q: Why is my GPRS, EDGE, or UMTS so slow?
>
> A1: SERIAL PORT BOTTLENECK

This wouldn't apply to GPRS, would it? How fast is a typical GPRS connection?

(Once again, please excuse this ex-CDMA user's non-grasp on GSM data specs.)

--
Steve Sobol, Professional Geek 888-480-4638 PGP: 0xE3AE35ED
Company website: http://JustThe.net/
Personal blog, resume, portfolio: http://SteveSobol.com/
E: [email protected] Snail: 22674 Motnocab Road, Apple Valley, CA 92307

[POSTED TO alt.cellular.attws - REPLY ON USENET PLEASE]

In <[email protected]> on Tue, 09 Aug 2005 21:49:59 -0700, Steve
Sobol <[email protected]> wrote:

>John Navas wrote:
>> Q: Why is my GPRS, EDGE, or UMTS so slow?
>>
>> A1: SERIAL PORT BOTTLENECK
>
>This wouldn't apply to GPRS, would it? How fast is a typical GPRS connection?
>
>(Once again, please excuse this ex-CDMA user's non-grasp on GSM data specs.)

GPRS can be as fast as the best 56K analog dialup modems in terms of bit rate.
While that's less than 115K port speed, higher port speeds decrease latency
and thus improve performance. This is because packet data is transferred to
the host *after* receipt of the entire packet by the mobile device. The
difference isn't large, but it can be significant.

EGPRS(EDGE) is of course a much bigger issue.

--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>

John Navas wrote:

> GPRS can be as fast as the best 56K analog dialup modems in terms of bit rate.

How fast is EDGE then? I was under the impression that it was around the
same speed as ISDN at the top-end.


--
Steve Sobol, Professional Geek 888-480-4638 PGP: 0xE3AE35ED
Company website: http://JustThe.net/
Personal blog, resume, portfolio: http://SteveSobol.com/
E: [email protected] Snail: 22674 Motnocab Road, Apple Valley, CA 92307

[POSTED TO alt.cellular.attws - REPLY ON USENET PLEASE]

In <[email protected]> on Tue, 09 Aug 2005 23:36:37 -0700, Steve
Sobol <[email protected]> wrote:

>John Navas wrote:
>
>> GPRS can be as fast as the best 56K analog dialup modems in terms of bit rate.
>
>How fast is EDGE then? I was under the impression that it was around the
>same speed as ISDN at the top-end.

I routinely get 150 Kbps on EGPRS(EDGE), significantly faster throughput than
ISDN.

--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>

In alt.cellular.cingular John Navas <[email protected]> wrote:
> GPRS can be as fast as the best 56K analog dialup modems in terms of bit
> rate. While that's less than 115K port speed, higher port speeds
> decrease latency and thus improve performance.

With a Motorola V220 and a USB cable to a 1.8GHz P4 laptop, I was finding
that higher port speeds led to slightly lowered throughput according to
www.dslreports.com/stest and ftp up/downloads.
At speeds above 115200, www.dslreports.com/mspeed wouldn't complete the
100k test, only the 5k, and sometimes the 50k.

I set my port speed to 57600, and saw the best throughput.

With a Motorola V550 in EGPRS or GPRS and bluetooth, I don't see the same
problem. It doesn't get any faster, but it doesn't get any slower. Since
EGPRS doesn't seem to be operating at its rated speed, I presume that I
have local conditions affecting me, and I've set my port speed to 230K, in
hopes that it will be better occasionally.

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

[POSTED TO alt.cellular.cingular - REPLY ON USENET PLEASE]

In <[email protected]> on Wed, 10 Aug 2005 14:02:13 +0000 (UTC),
[email protected] wrote:

>In alt.cellular.cingular John Navas <[email protected]> wrote:
>> GPRS can be as fast as the best 56K analog dialup modems in terms of bit
>> rate. While that's less than 115K port speed, higher port speeds
>> decrease latency and thus improve performance.
>
>With a Motorola V220 and a USB cable to a 1.8GHz P4 laptop, I was finding
>that higher port speeds led to slightly lowered throughput according to
>www.dslreports.com/stest and ftp up/downloads.
>At speeds above 115200, www.dslreports.com/mspeed wouldn't complete the
>100k test, only the 5k, and sometimes the 50k.

Take online speed tests with a grain of salt -- they're neither accurate nor
reliable, and they only measure streaming throughput, not interactive
throughput or latency, or even multiple connections.

>I set my port speed to 57600, and saw the best throughput.

Sounds like you have something else going on, port overrun perhaps. That
could be due to your computer hardware, device connection, or even the device
itself.

Here are some FTP throughput tests I just ran over a GPRS connection through
Cingular to a fast FTP server with a Sony Ericsson Z600 (GPRS Class 10) over
Bluetooth (Windows XP stack) using the Windows XP FTP client:

PORT SPEED 57.6 Kbps:

ftp: 51200 bytes received in 15.45Seconds 3.31Kbytes/sec.
ftp: 51200 bytes received in 13.45Seconds 3.81Kbytes/sec.
ftp: 51200 bytes received in 13.41Seconds 3.82Kbytes/sec.

PORT SPEED 230 Kbps:

ftp: 51200 bytes received in 11.35Seconds 4.51Kbytes/sec.
ftp: 51200 bytes received in 14.43Seconds 3.55Kbytes/sec.
ftp: 51200 bytes received in 12.54Seconds 4.08Kbytes/sec.

Note that there's considerable variation from trial to trial (primarily due to
network load and the packet-based nature of GPRS) -- it takes more extensive
careful testing (more than just three trials) to get reliable results. But
note nonetheless that the higher port speed didn't cause problems, and did
result in significantly higher throughput on average, as I've confirmed in
more extensive testing, which also shows that interactive throughput benefits
even more.

--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>

John Navas wrote:

>>How fast is EDGE then? I was under the impression that it was around the
>>same speed as ISDN at the top-end.
>
>
> I routinely get 150 Kbps on EGPRS(EDGE), significantly faster throughput than
> ISDN.


Depends onw aht you're referring to when you say "ISDN."

If you mean ISDN BRI (Basic Rate Interface), then the speed is 64kbps.

If you mean ISDN PRI (Primary Rate Interface), then the speed is 128kbps.

And if you're talking about 3-PRI bonded ISDN (the stuff used for
H.320/H.323 videonconference and for broadcast quality video and audio),
then the data rate is 384kbps.




--
E-mail fudged to thwart spammers.
Transpose the c's and a's in my e-mail address to reply.

"John Navas" <[email protected]> wrote in message
news:InfKe.8356$p%[email protected]...
> Q: Why is my GPRS, EDGE, or UMTS so slow?

A3. Network congestion. It's a shared medium. When more people are using it
you may have to wait for capacity.

A4. Access Point congestion. Probably could be A3b since the Access Point is
part of the network.

--
Donald Newcomb
DRNewcomb (at) attglobal (dot) net

Isaiah Beard wrote:

> Depends onw aht you're referring to when you say "ISDN."
>
> If you mean ISDN BRI (Basic Rate Interface), then the speed is 64kbps.
>
> If you mean ISDN PRI (Primary Rate Interface), then the speed is 128kbps.

> And if you're talking about 3-PRI bonded ISDN (the stuff used for
> H.320/H.323 videonconference and for broadcast quality video and audio),
> then the data rate is 384kbps.

Wrong, wrong, and wrong.

ISDN BRI is 2 "B" channels + a data channel. Each B channel can carry one
voice conversation or 64K of data. You can purchase single-channel ISDN
connections from an ISP (like the one I used to work for), but the telco
gives you 2B+D.

ISDN PRI is 23B+D. The total bandwidth, if you choose to use all of the B
channels for data, is 1472Kbps, just one channel short of a full T-1 worth
of bandwidth (T-1 is 1536Kbps of data, or 24 voice channels or some
combination thereof depending how you split it).

FYI.

--
Steve Sobol, Professional Geek 888-480-4638 PGP: 0xE3AE35ED
Company website: http://JustThe.net/
Personal blog, resume, portfolio: http://SteveSobol.com/
E: [email protected] Snail: 22674 Motnocab Road, Apple Valley, CA 92307

Isaiah Beard <[email protected]> wrote:
> Depends onw aht you're referring to when you say "ISDN."
>
> If you mean ISDN BRI (Basic Rate Interface), then the speed is 64kbps.

Huh?

> If you mean ISDN PRI (Primary Rate Interface), then the speed is 128kbps.

Huh?

> And if you're talking about 3-PRI bonded ISDN (the stuff used for
> H.320/H.323 videonconference and for broadcast quality video and audio),
> then the data rate is 384kbps.

Huh? 3-PRI bonded ISDN?

The numbers for PRI vary by where in the world you are, but BRI is 2 64K and
one 16K channel, and PRI in the US is about 10 times that capacity.

miguel
--
Hit The Road! Photos from 36 countries on 5 continents: http://travel.u.nu
Latest photos: Queens Day in Amsterdam; the Grand Canyon; Amman, Jordan

Is there an accelerated proxy server available (even by subscription,
or software that I could put on my own server) for TMO which would
increase the speed? Like Venturi on Verizon?

On 2005-08-10 02:23:39 -0400, John Navas <[email protected]> said:

> [POSTED TO alt.cellular.attws - REPLY ON USENET PLEASE]
>
> In <[email protected]> on Tue, 09 Aug 2005 21:49:59 -0700, Steve
> Sobol <[email protected]> wrote:
>
>> John Navas wrote:
>>> Q: Why is my GPRS, EDGE, or UMTS so slow?
>>>
>>> A1: SERIAL PORT BOTTLENECK
>>
>> This wouldn't apply to GPRS, would it? How fast is a typical GPRS connection?
>>
>> (Once again, please excuse this ex-CDMA user's non-grasp on GSM data specs.)
>
> GPRS can be as fast as the best 56K analog dialup modems in terms of bit rate.
> While that's less than 115K port speed, higher port speeds decrease latency
> and thus improve performance. This is because packet data is transferred to
> the host *after* receipt of the entire packet by the mobile device. The
> difference isn't large, but it can be significant.
>
> EGPRS(EDGE) is of course a much bigger issue.

Ridolph wrote:
> Is there an accelerated proxy server available (even by subscription, or
> software that I could put on my own server) for TMO which would increase
> the speed? Like Venturi on Verizon?
>
> On 2005-08-10 02:23:39 -0400, John Navas <[email protected]> said:
>
>> [POSTED TO alt.cellular.attws - REPLY ON USENET PLEASE]
>>
>> In <[email protected]> on Tue, 09 Aug 2005 21:49:59
>> -0700, Steve
>> Sobol <[email protected]> wrote:
>>
>>> John Navas wrote:
>>>
>>>> Q: Why is my GPRS, EDGE, or UMTS so slow?
>>>>
>>>> A1: SERIAL PORT BOTTLENECK
>>>
>>>
>>> This wouldn't apply to GPRS, would it? How fast is a typical GPRS
>>> connection?
>>>
>>> (Once again, please excuse this ex-CDMA user's non-grasp on GSM data
>>> specs.)
>>
>>
>> GPRS can be as fast as the best 56K analog dialup modems in terms of
>> bit rate.
>> While that's less than 115K port speed, higher port speeds decrease
>> latency
>> and thus improve performance. This is because packet data is
>> transferred to
>> the host *after* receipt of the entire packet by the mobile device. The
>> difference isn't large, but it can be significant.
>>
>> EGPRS(EDGE) is of course a much bigger issue.
>
>
>
My experience is that the data transfer on the EDGE PC card (Sony
Ericsson) is now less that it was. Before on a good day I could get
80kbits/sec download rate but now often only 5 to 10. Also it downloads
some then just stops. Sort of like they have a limit on the number of
bytes you can download in one session. I have not been able to get an
answer from Cingular about this.

"J Robertson" <[email protected]> wrote in message
news:MTGPe.1882$Bc2.1582@trnddc06...
> My experience is that the data transfer on the EDGE PC card (Sony
> Ericsson) is now less that it was. Before on a good day I could get
> 80kbits/sec download rate but now often only 5 to 10. Also it downloads
> some then just stops. Sort of like they have a limit on the number of
> bytes you can download in one session. I have not been able to get an
> answer from Cingular about this.

My old CDMA card on Sprint runs at a hardware 144Kbs but because of
compression the sustained rate while not moving is usually between 300 and
408Kbs. At 80mph, transfer rates drop to a little over 200Kbs.

I tested the new Verizon cards in a notebook and non-moving. They get burst
rates up to 4Mbs but their data coverage is only slightly better than a
barbed wire fence.

Is your 5 to 10 Kbs raw data speeds or compressed data?

[POSTED TO alt.cellular.attws - REPLY ON USENET PLEASE]

In <2005082420305275249%magnusspamridolph@spymaccom> on Wed, 24 Aug 2005
20:30:52 -0400, Ridolph <[email protected]> wrote:

>Is there an accelerated proxy server available (even by subscription,
>or software that I could put on my own server) for TMO which would
>increase the speed? Like Venturi on Verizon?

Many ISPs offer them for dial-up.

--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>