Why mobile apps suck when you're mobile (TCP over 3G)
blog.davidsingleton.org
Why mobile apps suck when you're mobile (TCP over 3G)
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Re: Why mobile apps suck when you're mobile (TCP over 3G)
#2Not that his advice is bad, but these statistics are a bit biased. Trains make for some pretty unusually difficult channel conditions.
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#3Not that his advice is bad, but these statistics are a bit biased. Trains make for some pretty unusually difficult channel conditions.
That may be, but - at least in my case - the most typical mobile usage is on a train (everywhere else I usually have WiFi).
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#4Not that his advice is bad, but these statistics are a bit biased. Trains make for some pretty unusually difficult channel conditions.
Trains moreso than cars/buses? Why?
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#5Not that his advice is bad, but these statistics are a bit biased. Trains make for some pretty unusually difficult channel conditions.
Really? I would say trains, buses and cars are really common use cases for mobile data. Every second person I see is watching Youtube or playing around on the internet while they take public transport. It isn't biased data, there is an actual use case that it is presently failing.
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#6Not that his advice is bad, but these statistics are a bit biased. Trains make for some pretty unusually difficult channel conditions.
Trains moreso than cars/buses? Why?
Faster travel meaning you are passing in and out of cells more often, and you are more likely to be passing through areas with bad coverage either for man-made geographical reasons (a steep embankment between you and most of the towers in range for instance) or because your route is more likely to take a straight-ish line that may pass through a pretty uninhabited area that is ether completely unserviced by the cell network or where the only tower(s) in range are some distance away. Also if you are travelling by bus (and to a certain extent by car) you are more likely travelling a shorter distance than if travelling by train so are less likely to be passing through areas that are badly served because there is no money in the networks serving the two local farmers as well as they serve a small town.
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#7Not that his advice is bad, but these statistics are a bit biased. Trains make for some pretty unusually difficult channel conditions.
Yeap. Trains going through rural areas, particularly with rolling hills can experience vast patches of no signal.
Even with flat land and line of sight to a base station, the signal is going to drop off with distance^-4, which is a lot quicker than in urban environments where it is distance^(-1.6 to -4). Finally base stations are fewer and further between in rural areas, so often you will be nearer the edges of the cell radius and experience worse signal and more cochannel interference!
But saying all that I do like the sentiment of the article and it is definitely good advice to design mobile apps for flakey connections...
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#8Interesting, suggests a quick fix might be for the client to not use keepalive, or to selectively close connections that are very slow so as to start new ones. Potentially a much easier solution than writing a new transport.
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#9The problem for those of us on capped and/or expensive-per-kbyte mobile connections (in the UK that is everyone who doesn't spend a large chunk on their monthly contract - people on Virgin pay-as-you-go pat £3 for a day's access but IIRC you get cut off after 25Mbytes in that day) with restarting connections early is that the ~20 seconds worth of packets queued up during the blip is going to be sent anyway even though they are now no longer needed. 20 seconds worth of discarded packets could be quite a bit if you were transferring data at decent 3G+ speeds just before the blip.
Re: Why mobile apps suck when you're mobile (TCP over 3G)
#10Earlier quoted context omitted.
Trains moreso than cars/buses? Why?
Faster travel meaning you are passing in and out of cells more often, and you are more likely to be passing through areas with bad coverage either for man-made geographical reasons (a steep embankment between you and most of the towers in range for instance) or because your route is more likely to take a straight-ish line that may pass through a pretty uninhabited area that is ether completely unserviced by the cell…
Trains also dampen the signal. Many German high speed trains have repeaters but those don't yet (hopefully!) work with UMTS. Cars and busses have admittedly the same problem but maybe to a lesser extent.