Author: Martin

I am sitting in a Starbucks in Miami after an intensive conference week right now and starting to reflect on what I have seen and noted during the week. One of the straight forward things that comes to mind about last week is that conference organizers, especially in the high tech sector, have to ask about the details of Internet connectivity of the place they want to use. Just having Wi-Fi in a place is not enough, capacity on the backhaul link is even more important. In our case, 300 people were rendered without a usable Internet connection for the week because the backhaul was hopelessly underdimensioned for the load. When I arrived as one of the first on Sunday, the best I got was about half a megabit per second. During the week it was a few kbit/s at best. eMails just trickled in and using the Internet connection for Voice calls was impossible.

While some might see this just an inconvenience and argue that you should concentrate on the conference anyway there are others, like me, that require to answer a couple of eMails and call people throughout the day to keep the normal business going. So instead of making free calls, I and many others had to fall back on their mobile phones and paid a dollar/euro or more per minute due to high roaming charges. The extra cost of that to the company multiplied by 300 is significant. Last year, same conference, different venue there was an 8 MBit/s backhaul link and things ran a lot smoother. But I guess by next year, even that will not be good enough anymore to keep things going when 300 engineers arrive.

P.S.: Good that I had my AT&T prepaid SIM card. With the MediaNet add-on I could access the net and get to my eMails via AT&T’s EDGE network. Definitely not at multimegabit speed but a lot faster than over the hotel’s Wi-Fi.

While well dimensioned 3G networks are offering fast Internet access today, some somewhat underdimensioned networks show the first signs of overload. Some industry observers argue that the answer is to introduce tiered subscriptions, i.e. the user gets a guaranteed bandwidth or a higher bandwidth if he pays more. But I am not sure that this will work well in practice for two reasons: The first reason is that when some users are preferred over others in already overloaded cells, the experience for the majority gets even worse. And second, if such higher priced subscrptions get more popular because the standard service is no good, it won’t be possible at some point to statisfy even these subscribers. So such gold subscriptions just push out the problem a bit in time but otherwise don’t help a lot. There is just no way around sufficient capacity or your subscibers will migrate to network operators who have made their homework. So instead of only investing in QoS subscription management I would rather also invest in analysis software that reports which cells are often overloaded. That gives the operator the ability to react quickly and increase the bandwidth in the areas covered by such cells. Having said all of this, what do you think?

Here I am, back in Italy and again using my 3 UK SIM for Internet access, since there are no data roaming charges between 3 networks in different countries. Very interesting and also a bit depressing to see the performance throughout the day. Sunday morninig 8 am seems to be a pretty quiet time and I easily got 1.5 MBit/s in downlink. Evenings seem to be high time, with data rates dropping to less than 300 kbit/s and long page loading times due to lots of lost packets. I am pretty sure it’s not a cell overload since the Wind UMTS network at the same locations easily gives me 1 MBit/s and no packet loss in direct comparison. So the bottleneck is either the link back to the home network or the GGSN in the UK .

While it’s good to see the networks being used and affordable data roaming in place, I’d appreciate sufficient capacity in the core network.

Since I travel a lot, I often stay in hotels. One thing in hotel rooms I could live without is the TV set, as I never have the desire nor the time to watch anything anyway. In recent years, however, I've noticed that good old cathode ray tube TV's are giving way to TFT TV's. Last week I took a closer look and noticed that these TV's usually also have a VGA or DVI input. Excellent, now I can finally put them into good use and connect them to my notebook as a second screen. All that is needed is a VGA or DVI cable, which I will take with me from now on. The picture on the left shows how my typical hotel setup looks like. Screen 1, screen 2 and a 3.5G HSPA modem for Internet connectivity. Almost as good as at home 🙂

In a comment to a recent blog entry somebody left a link to an interesting S60 utility that records power consumption and other interesting technical information while Noka NSeries and other S60 based devices execute programs. Running in the background, one can perform actions and see the impact on power consumption. The picture on the left for example shows power consumption during different states during mobile web browsing.

The left side of the graph (click to enlarge) shows power consumption while a web page is loaded, i.e. while the device is in Cell-DCH / HSPA state. Power consumption is at almost 2 watts during this time. Once no more data is transferred, the mobile is set into Cell-FACH state by the network which requires much less power. However, the 0.8 watts is still significant. After about 30 seconds of inactivity the network releases the physical bearer and only maintains a logical connection. In this state, power requirements drop to about 0.2 watts which is mostly used for driving the display and the background light. When the device is locked and the background light is switched off, the graph almost drops to the bottom, i.e. to less than 0.1 watts.

An excellent tool to gain a better understanding of power requirements of different actions and processes!