WirelessMoves

It’s summer time in the northern hemisphere and I keep getting eMails from people asking for my advice on how to access the Internet in countries to which they intend to travel. In the past I’ve reported on quite a number of 3G prepaid wireless Internet access offers mostly of operators in Europe. Prepaid is the important word in the previous sentence as travelers can not get postpaid contracts even if they are without a minimum subscription time or monthly fee.

Over time, these reports have become a bit difficult to find on the blog. Those that dig a bit eventually end up with this summary. However, it’s still not ideal to search through the collection of articles in the hope to find the right piece of information. Thus, I’ve decided to open a Wiki for everyone to participate and share information! All the information I have collected so far on how to wirelessly access the Internet with a prepaid SIM card can be found there now.

One person can not do it alone! So if you have additional information, please consider updating the pages or to create new ones. No login required, just hit the edit button. If you think this information is useful for others please consider linking to the Wiki or writing a blog entry about it! That’s the only way people will eventually find the information when searching on Google, Yahoo, etc.

UMTS Femto cell solutions are being announced lately by both startups and established players such as Nokia Siemens Networks. Leaving aside the question of whether femto’s make sense or not I tried to find out how femto’s can be integrated with the macro layer of the network. It seems not to much information is available about the technical part on the net. So here are my questions, maybe some of you know more. If so please consider leaving a comment.

Basically I’ve seen two approaches to femto. For both cases, the cells are connected to the network via DSL or cable:

Pure Base Station Approach

In this approach the femto cell is included as part of the overall radio network. This should require configuration of both the femto cell and the macro cell layer for handovers and cell reselection. I’ve seen some patent applications from Ericsson which describe that the pico cell is equipped with a receiver that can scan the environment for neighboring cells. The result is then reported to the network which in turn sends the required neighboring cell lists to the femto for broadcast. Nothing is mentioned, however, of how the macro layer is configured. If this is not done, I wonder how a mobile in idle mode can change to the femto cell.

Also, I wonder if it is foreseen to restrict access to a femto cell to the owner of the cell? After all, if I had a femto cell at home, would I want my 25 neighbors to also use it for free? If access can be restricted how is that done? Should the macro layer broadcast the cell info for my femto cell, others will see it as well. And if it doesn’t, how can my own mobile detect the femto cell once I arrive home and still have coverage from the outdoor macro cell?

Speculation: While a mobile has a connection established to the network it can be asked to report cells which are not in the cell info list (the so called "detected cells" broadcasting on the same frequency as the current cell). This could then be used by the RNC in combination with with my user ID to decide whether to hand over the connection to the femto cell, in case the owner of the mobile is the owner of the femto or to leave the call on the macro layer. This does not work when the mobile looses connection to the macro cell layer, however. In this case the network search of the mobile will detect the femto and the mobile will try to attach. How can this be gracefully prevented in case the femto only allows a select few users?

Scalability: If it can be avoided that the macro cell layer has to broadcast information about the femto cell layer then I don’t see scalability issues on the Node-B side. If it can’t be avoided then I wonder how the solution scales. A macro layer cell is usually designed for about 2000 users. If ‘only’ 50 of them use a femto cell at home I wonder how this can be accommodated for in the neighboring cell list!?

The Network In A Bottle Approach

Another femto approach used for example by 3WayNetworks is to combine the complete functionality of the network from base station to MSC into the femto base station. On their web site, 3WayNetworks mentions that the femto base station can use a different Mobile Country Code and Mobile Network Code and thus runs completely independent from the macro layer. This might make rejecting unauthorized users a bit simpler than in the approach above but still leaves open the question of how authorized mobiles find and use the cell in the first place in case the macro layer is still strong enough where the femto cell is to be used (e.g. to increase overall network bandwidth).

Speculation: Here, an old GSM trick could help which probably still exists for UMTS: For national roaming the mobile can be instructed to scan for the home network every couple of minutes. Femto subscribers could be given a SIM card which the femto’s MCC/MNC as home network. Thus, femto subscriber mobiles would keep looking for femto cells while other subscribers could automatically be barred. UMTS also knows the concept of equivalent network which might also help here (see 3GPP TS 22.011 chapter 3.2.2.5).

A lot of questions… If you have an answer, please leave a comment.

Carlo Longino points out on his blog that Steve Jobs has said battery capacities and immature 3G chipsets that take too much power are the reason the iPhone doesn’t have any 3G capabilities. If you want to build a phone these days that is designed for only being used for a two minute voice call once or twice a week, using a 2G chipsets is surely the right thing to do as standby power consumption is definitely lower than what 3G chipsets can do today. However, the iPhone is a multimedia device and is built for being used throughout the day for a myriad of purposes. Therefore 3G chipset power consumption is the least of your worries.

Compared to what the processor, display, background illumination, camera and memory consume during intensive use during the day, the additional power required for a 3G chipset while in standby is not worth mentioning. Even without a lot of network use my battery on the N93 is flat in the evening when I heavily use my phone during the day for taking pictures, navigating (NokiaMaps), taking notes, checking and responding to eMails, playing games, reading documents, etc. etc. All of this requires little to no network interaction. On days without a lot of activity the battery is still almost full in the evening, despite having been attached to a 3G network all day long. So 3G chipset idle mode power consumption is definitely not an issue if the phone / multimedia device is used heavily during the day.

But once you use the cellular network it doesn’t really matter if you use a 2G or 3G network. In both cases the battery is flat after two to three hours if I use the phone together with a notebook to access the Internet. I don’t think the iPhone is designed to do this but the same is true for using the network with the built in browser.

I wonder if Apple’s decision not to include 3G has more to do with the fact that you can count the number of 3G or 3.5G capable mobile phones (not datacards) in the U.S. on one hand these days. Compare that to Europe where 3G in mobile phones are already mainstream technology. If Apple had been a European company it could well be their decision would have been different.

About one and a half years ago I first reported about Nokia R&D Labs great idea to port parts of the Apache Server code over to the S60 OS mobile phone platform. The web server in your pocket, a strange idea maybe at first but with a lot of potential. At the time I mused in this blog post how I would use it in my daily live. Now, Nokia has released the project to the public and created a single installation file that contains everything. Thank you Tommy for posting it on your blog!

It seems that what I was writing about previously and much much more has found it’s way into the first version. As described before, a mobile web server can be used for sharing content created or stored on the phone with other people. The owner of the phone also benefits from the web server himself as he can use a web browser on a PC to quickly and comfortably access the mobile phone via the web browser to search for a name in the contact list, to look at his calendar, to create new meeting entries, to send SMS messages, etc. etc.

Of course I had to immediately install the web server on my N93 and give it a try myself.

How To Access The Web Server

Via the Internet: After registration on Nokia’s Mobile Web Server Site and installation of the mobile web server (a single .sis file) on the mobile phone, the web server can be connected to the Internet. If connected via a cellular network, the owner or other people can use the URL assigned during the registration process (e.g. martin.mymobilesite.net) to access the phone.

It’s important to note that the URL is not directly registered to the IP address of the mobile phone but instead leads to the Nokia project site which forwards the request. This is necessary as many mobile operators do not give out public IP addresses and thus computers on the Internet can not reach the mobile phone directly. The Nokia project site, however, is contacted by the mobile web server at startup and thus has an open TCP connection that can be used for forwarding the request.

Via Wifi: Many N-series phones can be connected to the Internet via Wifi. This has the advantage that the owner can not only contact the phone via the Nokia project server but directly with a notebook or PC connected to the same Wifi network. This has the advantage that pages are sent much faster as the data is not sent once to the Internet and back.

Applications

A web server is nothing without static and dynamic pages it can supply to web browsers. Thus, the mobile web server already comes with a number of server side applications and access to each application can be permitted or denied per user or per group. Here are my favorites:

Camera Application: Permitted users can invoke a server side application that takes a picture with the phone’s camera which is then returned to the web browser. An excellent way for home monitoring purposes!

Share Photo Albums: Pictures stored on the phone can be assigned to photo albums which users can access once the owner of the phone gives them access. Very nice, one photo album from my friends, one for my parents, one for business partners, etc. etc.

Contact List Browser: Instead of searching for a contact on the mobile phone, permitted users can search addresses and phone numbers stored on the phone. This is probably an application that the owner wants to restrict to himself. By default all applications are restricted to the owner and thus access to any sensitive information is not given out by default. Excellent default security policy!

Calendar Application: The phone’s calender can be viewed and new calender entries can be created in the web browser. The picture at the beginning of the blog entry shows how the application presents the calendar entries for a week.

Send SMS messages: Gone are the days of fiddling around with the keys on the phone when writing an SMS. Now, the SMS can be written in the web browser no matter if the phone is next to the notebook or 5000km away.

WebDAV: I like to use my phones as a storage device to take files with me or to make a quick backup. So far I always had to connect the phone to the notebook with a cable or establish a Bluetooth connection to transfer the files. With WebDAV the phone can now seamlessly share files and folders with a PC. The picture on the left shows how the file system of the phone is integrated into the PC’s file explorer tree structure. Files can be copied to and from the WebDAV drive, renamed and deleted. As with all other server side applications the owner of the phone can assign access rights to individual users. For Windows XP no additional software is necessary. When connected via Wifi, file transfers to the phone are done with a speed of about 50 kbytes/s. Transferring a file from the phone to the PC is almost done at light speed, I measured around 600 kbytes/s.

Create your own applications: The mobile web server is open for additional server side modules and a Python interpreter is also included. Want to query an external GPS receiver to create a page that shows your current location? No problem, Python can do the trick and only a text editor is required to write the code. Fabulous. More information can be found here.

Battery Usage

Surprisingly, battery usage while connected via Wifi does not seem to be very high. I’ve had the phone connected for 5-6 hours today and the battery indicator only decreased by two bars. Needless to say I also used the phone during the day for a lot of other things so the web server and the Wifi chip where not the only ones using the battery sucking on the battery.

Summary

I am absolutely thrilled to see such a complete suite of applications to be delivered with the first version of the server. Also, the user management is superb as it allows to give access rights for each application to individual user or per groups Thus, the owner can restrict applications like the calendar, SMS sending and the contacts to himself while sharing photo albums and grant access to take snapshots with the camera to selected other users. Overall, I think this is a project that will surely generate interest and hopefully a lot of interesting user supplied modules and Python scripts.

In countries such as Austria and Italy, mobile operators are heavily promoting the use of their HSDPA networks as an alternative to DSL access at home. Pushed by very interesting prices starting at €10.- a month for 250MB, €20.- for 3GB and €50 euros for 20GB in case of One in Austria, only the sky seems to be the limit.

I’ve recently been in Austria and talked to a number of people using these offers. Being mostly students, they like Internet access via 3G networks for two reasons: For many it’s cheaper (!) than DSL at home and they usually use it with a PC card and a notebook not only at home but also in other places.

For families, however, the equation might look differently. In many cases, several PCs or notebooks are available in the household and thus Internet access needs to be available to all family members. It can be done wirelessly for example by using a 3G/Wifi Access point but it of course immediately takes mobility out of the equation. On top, if you have kids then any kind of usage cap is just waiting to be stepped over as soon they start using file sharing applications, music downloads, YouTube and other bandwidth intensive applications.

Looking Ahead

So in the long run I expect mobile households to use DSL or cable coupled with Wifi to share a flat rate fat pipe with all members of the household, 3G/4G data cards in their notebooks for Internet connection while on the move and mobile phones which make good use of high speed wireless networks (3G, 4G and Wifi while at home) for anything from podcast downloads to video sharing. Wifi at home also has another advantage over using the 3G/4G network: It’s possible to communicate with your network enabled household appliances such as digital video recorder, music library, other PCs, mobile phones, etc. A good step towards the hyperconnectivity vision of Nortel’s CTO John Roese.

In such a scenario I it’s quite o.k. to have reasonable volume caps in place for 3G and 4G networks. This encourages the use of DSL/cable at home where I think most data traffic will occur due to the availability of big screens which require a much higher bandwidth for video applications than small screens on the mobile phone. Also, people have much more time available at home to communicate, to work and to play. After all, no matter how far 4G will push wireless capacity limits, DSL, cable and fiber will have infinitely more capacity available than wireless systems.

Network operators with both fixed line and wireless assets will surely figure out how to make interesting dual offers and can thus insure that the DSL/cable backhaul and not their wireless network deals with most of the data traffic. The high speed cellular network will then only be used as an overlay network by most people when leaving their Wifi cloud.

Surely there will also be people that use the 3G/4G wireless network as their sole access to the Internet. I expect, however, that their number is small compared to "converged" users which increases the chances that enough capacity is available to transfer their data traffic alongside the data traffic from people using it as an overlay network at a comfortable speed.

As always, comments are welcome!