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Eugen

Hi, I had a very good experience in Italy with 3. I used the "naviga 3" option that allows you to surf 50 MB a day for 30 days. It costs only 9 Euros and is available on prepaid cards. I used a trick to buy an LG U300 for only 39 Euros and used it as a modem. Don't know how fast is was, but it was really fast (and cheap)

Gopi

Hi

Can you share the pcap files for the both the nws (downloads).

Regards,
Gopi

Stefan Blomeier

hi Martin,

I think that there could be two UTRAN reasons for throttled throughput.
A) the Iub-bandwidth is insufficient for high speed traffic (not properly dimensioned)
B) the SGSN tells the SRNC via the RAB Assignment not to go for higher throughput rates than e.g. 384 kbit/s in downlink and uplink ( peak data rate)

To A):
======
The E1 line may allow only for about 1.8 Mbit/s user traffic as ALCAP, NBAP, NodeB Sync and NodeB O&M occupy some fixed capacity. If there is additional Voice or DCH-traffic on that E1-line, the high speed traffic gets reduced. Most likely Vodafone uses CBR for DCH-traffic and UBR for HS-traffic for the Iub AAL-2 connections. Whenever CBR traffic is high, less capacity is available for UBR and so you will not get the max throughput for your category 12 data card.

To B:)
=====
Because of the E1 limitation Vodafone SGSN only allows a peak data rate of e.g. 384 kbit/s even for high speed. Maybe unless you are a Vodafone post paid user you get more bandwidth. In any case the SRNC strictly follows that peak data rate limitation and only forwards every 10ms only 12 Blocks each of a size of 320 bits (= payload of MAC-d). The NodeB wraps these 12 packets up in an HS-DSCH fat/jucy Block and sends within 2ms to the UE. The UE delivers to the applications only every 10ms a burst of 12 blocks.

what do you think?

kind regards,

Stefan

Martin

Hello Stefan,

I am quite certain that the traffic shapping is enforced by the visited SGSN since it happens in 3 foreign countries while in Germany I get the full speed with my prepaid SIM card and a websession. Also in Austria I get the full speed with my German Vodafone SIM card and a websession in the network of A-1. The question is why this limit is imposed. Either the SGSN is imposing it on it's own for an unknown reason or, and that's my theory, maybe these networks are using an old version of the MAP protocol that can't convey the information about HSDPA data rates between the HLR in the home network and the SGSN in the visited network. I darkly remember that for HSDPA enhancements were necessary in the HLR to describe the higher data rates. Note sure if that had an impact on the MAP protocl as well.

What's also very puzzeling is the high IP packet loss in some networks which leads to dup acks and consequently highly variable and generally low overall transmission speeds. I've seen it in the Italian WIND network and the Spanish Yoigo network with local SIM cards and also in the Italian Vodafone network. I've tested with two different HSDPA terminals and in the Yoigo network with an old Nokia 6680 UMTS only mobile always with the same IP loss (or re-ordering) result. I also tried different IP max. packet lengths by forcing fragmentation but it didn't change anything. Also different times of day and night did not change the behavior so I can exclude busy hour effects. I've got Wireshark traces of the issue, if you are interested I can forward them to you :-)

Thanks for commenting and best wishes from Madrid,
Martin

Pierre

Hi Martin,

I am looking for a capture tool doing pcap captures (like tcpdump, winpcap, wireshark) on symbian phones (especially S60 for E61). Is there any such tool? That would be great for further performance testing along your lines!

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