Category: wireless

Why are 3G networks so slow?

More than four years ago one of my friends wrote about uselessness of UMTS connections (the page has decayed into digital wasteland in the meantime) for inter-router backup links and although I got numerous comments trying to explain the issues I never found a good explanation that a simplistic networking engineer like me could understand.

Ilya Grigorik fixed that. His Breaking the 1000 msec Time-to-Glass Mobile Barrier talk has some real-world statistics, and a fantastic description of how 3G/4G networks work and what causes the enormous latencies. His High Performance Browser Networking book has even more details. Enjoy!

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Where could we expect to see Wimax?

In another Ask the Expert topic, I’m answering the question on expected Wimax deployment scenarios. Although I personally believe it’s a better technology than LTE (and obviously I cannot comment on the RAN part of either), I don’t expect existing mobile operators to pick it up, as they’ve thrown too much money into the GSM/HSCSD/GPRS/EDGE/UMTS/HSDPA/HSUPA neverending story.

To submit your own question to the Ask the Expert project, use this link.

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Weird GPRS and UMTS latency

Bad designer sent me an interesting comment: 2G and 3G networks have huge latency issues. GPRS is intolerable, UMTS is awful and HSPDA is reasonable but still not what one would hope for.

The latency does not seem to be associated with serialization delay. UMTS gives you reasonable transfer rates and significant latency and GPRS gives you an order of magnitude higher latency than ISDN with comparable transfer rate. If anyone knows enough about the mobile technologies to explain this phenomenon (or at least give me useful pointers) I’d really appreciate your comments.

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Wimax: the next disruptive technology?

Fifteen years ago, the focus of the “true” service provider was on voice traffic and data offerings based on virtual circuits, implemented with a plethora of semi-compatible technologies slowly developed within the ITU organization: X.25, ISDN, Frame Relay and the all-encompassing ATM.
In the meantime, some relatively small companies (including Cisco, Wellfleet and 3Com) were producing so-called “routers” that supported two technologies nobody took seriously: Ethernet and IP.

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