Nokia N900 - Connectivity and Woe

by Tina Holmboe 4th of April 2010 (archive)

When the N900 was first introduced it was made clear that this device was meant to be «always on» — the theoretical ideal for an «Internet tablet». In practise it means that one or the other of its built–in connections are active, and transmitting, at any given time.

And, as so often is the case, the ideal is not particularly practical. There are less real–life wifi hotspots than one could wish; fewer still that cost nothing to use. I won’t even touch the roaming–problem.

GSM/GPRS/3G is a different matter — it roams very well, is more or less global in presence, and provide speed enough for most tasks. But it ain’t cheap, and the existence of flat rate data packages is not global. When it comes to international roaming the bets are all off anyway.

Then, of course, there’s the battery–life. This isn’t, as it turns out, such a problem on the N900 — but more on that in a later post.

As I am due a trip to Paris, and therefor looking at £2.2 per MB rattling out of my account, the control of traffic on the ever–connected tablet cum phone is of great interest. It is easy enough not to use MSN/IRC — as is my habit — when outside my unlimited–data–plan area. What becomes troublesome is getting mail, since such things as critical service messages from my company’s servers wait for no woman; holiday or not.

The N900, being a Linux computer, makes it easy to check how much data is going in and out; simply run the /sbin/ifconfig –a command from the xterm and look at the RX and TX fields for the gprs0 interface … or you can install the «Personal Dataplan Monitor» widget which does it for you.

With this widget we can monitor exactly what is transmitted. The counter can be reset by way of «Settings» –> «Phone» –> «Data Counter» –> «Clear» and remember to add data UP to data DOWN, lest you have unpleasant surprises.

In order to keep the data low, however, we have several options.

First of all the all–encompassing «offline» mode, easily reached through a light push on the on/off button. The problem with this is, of course, that it turns off power to the antennas. That cuts down on traffic cost, but it leaves you without any form of communication, including SMS and phonecalls. Not ideal.

Sidenote: anyone ever tried to explain to an airline that, yes, offline mode means it doesn’t transmit anything, and that, no, I don’t have to turn the phone off…?

Then there’s the «Cellular Modem Control Buttons» application, which is activated by the power button (one light push!) and gives you easy access to a so–called «tablet mode» — which means the cellular antennas are off, but the wifi is kept on. This brings us back to the roaming problem.

On the flipside is the «Wifi Switcher» statusbar plugin [sic] which turns wifi on and off by unloading/loading the required driver modules from the kernel. Very nice for saving battery–power, but it doesn’t do much to save on cellular data costs …

The «AutoDisconnect» application, on the other hand, does. It’ll close your idle connections after a specified amount of time and traffic. Yes, it is designed to save on battery life, but it’ll also cut down on the amount of data transmitted.

Of course, it’ll help quite a bit if I turned off such things as the Facebook–, weather, and RSS–feed widget. Which I will.

Under normal circumstances — ie. the weather widget up, mail checked every 15 minutes, no MSN or IRC, I appear to use 2.87MB per hour. That, in turn, becomes 152 quid per day. Not amusing.

Now for skinflint mode. I’m turning off the Foreca Weather widget, and set Modest to check for mail once every hour. AutoDisconnect is set to turn off any GSM/GPRS/3G connection if idle more than 60 seconds. This results in 132 Kb per hour, or 7.7 Mb per 24 hours — and a total cost of £17 a day. This is far more reasonable, yet not good.

Two problems became apparent: first, Modest appears to check imap far more often than what I’ve told it to do, and secondly … something else is connecting. Luckily tcpdump is available.

My suspicions were confirmed. Modest make requests to the imap server every 8 minutes, regardless of the one hour limit I’ve set. This is enough for me to conclude that Nokia need replace their mail client with something that works.

Setting the mail client to not update automatically leaves us with so few bytes that the counter doesn’t register. This is more like it, but a huge disappointment in terms of connectivity.

A good mail–client for the N900, with notification, is highly desired.