2 Day WiMAX Course at the University of Oxford

Uox2
Today a little bit of self advertisement which might be of interest to those of you in the WiMAX business: On June 12 and 13, Chris Beardsmore of Intel, John Edwards of PicoChip and myself will host a 2 day WiMAX course at the University of Oxford’s Department of Continuing Education.

I am very proud to be part of this trio and each of us has a different angle on the technology. Chris has been working on the WiMAX business development side for many years and has a lot of information to share of how WiMAX is doing from that point of view. John is the air interface expert and will share his knowledge about the in’s and out’s from basic OFDM to MIMO. And myself, being the core and radio network guy will concentrate on the WiMAX core network, the radio network, authentication, mobility and session management and lots of things around it.

So, if I have caught your interest, head over to the course’s web site for the details. During this week, there are also a number of other wireless courses given by industry experts ranging from mobile web to the latest on HSPA and LTE. So if you have a bit more time to spend, it’s very well worth to stay a few extra days!

Power Consumption in 2G/3G Connected State

Some years ago, when I tested how long the battery of a mobile phone would last when a mobile device was connected to a 2G or 3G network (PDP context established) but not transferring any data for most of the time. At the time, the result was quite clear: I could almost watch almost in real time how the battery level decreased. Looks like things have changed pretty much in the meantime.

Idlemode
When repeating the test these days with a Nokia N95 and a Nokia N82, one being connected to an EDGE network and the other to a UMTS network over the course of the day while transferring almost no data, there seems no difference anymore to the device not being connected throughout the day. The picture on the left shows a screenshot of my N95 that was connected to an EDGE network throughout the day. Note that at the time the screenshot was taken, the mobile was also connected to a Wireless LAN network (i.e. some applications used the EDGE connection, others the Wifi connection). The same test with the N82 that was connected to a 3G network showed the same result.

Very good, one thing less to be concerned about! No more advice about disconnecting from the network due to the fear of running the battery into the ground quickly.

Virtual Geocaching Beats Chaos Organization

I am glad to have the Internet in my pocket to help in situations when the organization of others make success without pain highly unlikely. Take the follwoing scenario that happend to me recently: A theater visit is organized (note the passive in the sentence) in a city none of us have visited before. Turns out instructions concerning how to find the theater are practically worthless. People in the town are helpful but have different opinions on where the theater is ranging from ‘just aroundd the corner’ to ‘at the other end of town’. So here the Internet and navigation on my Nokia N95 comes to the rescue. Googeling for the town’s and theater’s name reveals the address and phone number of the theater immediately. Ah, the theater has three stages throughout the city. That explains the different opinions of the locals. A quick look into a local newspaper reveals the theater for the play. O.k., since Google has found the address, a quick look with Nokia Maps shows us the exacct place and guides us to the theater. How nice, how painless 🙂 Needless to say that the bus driver of the other group was one hour late since he had no one finding the details with his phone.

OperaMini Tip of the Week: Default Access Point

I use OperaMini day in and day out as my prefered browser and love the experience. Well, except for one thing, the frequent network selection dialog boxes. Some say it is an S60 feature but in my opinion this is just a big bug in the software. Anyway, Constantine from Intomobile now provided a great solution to the problem: In the S60 application manager, it is possible to define the behavior for each Java program. To get rid of the stupid dialog boxes, open the application manager, select OperaMini, select Open, and then set ‘Network Access’ to ‘Ask first time’. Afterwards, no more stupid dialog boxes. Thanks, Constantine!

The only drawback seems to be that one has to select a default access point when the setting is changed. This makes it difficult to use OperaMini over the Wifi network at home when the default access point has been set to the cellular network. Well, I guess you can’t have it all.

Wireless on Sicily – When Choice is the Rescue

In an earlier post , I reported on how I am using my 3 UK SIM card in 3’s Italian network for Internet access without roaming charges. This works well in the bigger cities such as Catania, Siracusa, etc. In smaller cities on the countryside, however, coverage is a mess. Often, there are at least three GSM networks and usually also some UMTS network while outdoors. But once inside somewhere, most networks just fade away. Or even worse, your mobile shows average coverage but as soon as you try to do something, the coverage indication goes away… In my apartment for example, there is complete radio silence except for 3’s UMTS network at the window. At another place where I stay sometimes, only TIM has reasonable coverage. It almost looks like in those smaller towns they just dropped a couple of base stations and never did any proper radio planning and interference analysis. So since SIM cards are cheap and Internet access to be had for a couple of Euros, I now have a SIM card for 3, one from TIM and another one from WIND. At least one works in any place. Not ideal, but pragmatic…

A Glimpse Of Data Roaming As It Should Be

I am in Italy at the moment taking a short vacation and experiencing my first ‘glimpse of data roaming as it should be’: A couple of weeks ago, I picked up a ‘3’ Prepaid SIM card in the U.K. for Internet access while being in Oxford. For 10 pounds a month, one can activate a one gigabyte data option. In addition, ‘3’ doesn’t charge extra for roaming, while using one of their SIMs in one of their other networks. So here I am in Sicily, a thousand miles away from Britain, using the UK SIM card in 3’s Italian network and it works just fine. Since the add on I activated in Oxford three weeks ago lasts for 30 days, it covers my time in Italy as well. Excellent, thanks 3, that’s how it should be! I just wished you had networks in more countries!

The Ultimate Test: The N82 In The Hands Of A Non-Techie

The constelation seems right: N-series devices becoming more mature and mobile Internet access now affordable, it’s time for the ultimate test: How will a Nokia Nseries device fare in the hands of a non-techie for more than just voice calls? I don’t have the answer yet, the ‘experiment’ has just started, but I should know soon enough. After testing the N82 in and out for a week, I finally shipped it to ‘the user’ with 4 applications preconfigured: MP3 player with 40 or so CD’s preloaded, Profimail for eMail access, picture upload to Flickr and OperMini 4.1 beta for mobile web access. In addition, the phone will be used intensively as a data modem for the PC. So let’s see how that works out. I’ll keep you posted.

More HSPA+: Enhanced Cell-FACH

HSPA+ is about more than just higher data rates, it is also about enhancing the radio interface to allow more devices to simultaneously connect to the network in a more power efficient way. I’ve described most of those features in various blog entries in the past but it seems I have missed one feature: Enhanced Cell-FACH.

One of the challenges of always on Internet connectivity is that mobile devices or PCs running instant messaging applications, Voice over IP prgrams, push eMail and other connected programs are anything but silent even while these applications are just running in the background. Even if just one of those applications is running, the device transmits and receives several IP packets per minute to keep the connection to the servers on the Internet alive. This means that in most cases, the radio link to mobile devices is not in idle state for most of the time.

As keeping the mobile in a fully connected state while only little data is transfered is quite wasteful in terms of bandwidth and battery capacity. UMTS networks therefore usually set device into the so called Cell-FACH state, once they detect that there is only little activity. In this state, the device uses the random access channel to transmit IP packets in uplink and the Forward Access Channel (FACH) in downlink to receive IP packets.

This method is quite efficient for the mobile, since no power control is performed on those channels. Hence, there is no radio layer signaling overhead in this state, which leaves more air interface capacity for other devices and also saves battery capacity. For the network, however, managing more than a few mobiles per cell on the FACH is not as efficient, since the channel was never designed to function as an always on data pipe for a high number of devices.

This is where the Enhanced Cell-FACH extension comes in. Once mobiles support this feature and they are set into Cell-FACH state, their data packets are sent on a Highspeed Downlink Shared Channel (HS-DSCH) instead of the Forward Access Channel. This improves the efficiency of downlink transmissions and also speeds up a state transmission into dedicated state once more packets are transferred again. An application note by Rhode and Schwarz goes into the details in Chapter 6.

What puzzles me a bit at this point is two things:

  • When will the feature become available?
  • In Cell-FACH state, the mobile is identified via the Cell-Radio Network Temporary ID (C-RNTI). In theory, this is a 16 bit value, i.e. up to 65536 mobiles per cell could be in Cell-FACH state simultaneously. Strangely enough, most networks only seem to increase this value up to 0xFF (256) before the being reset back to 0. Anyone got any idea why?

AT&T Starts Prepaid Internet Access For Mobile Devices

Great move from AT&T in the US to be the first GSM  / UMTS carrier in the region to start a small screen Internet access offer on prepaid SIMs. For $19.99, the ‘MediaNet Unlimited’ offer is not the cheapest I have seen, but definitely a good start! Can’t wait to try it out next month when I come to Orlando to speak at a Tech Conference. For the technical details take a look here at the Prepaid Wireless Internet Wiki.

Thanks to phonenews and Matthew Stevens, who’s blogging over at DarlaMack, for pointing me to it!