A True World Band GSM and UMTS Data Card

Sierra
In an ideal world, the same radio frequencies would be used for wireless systems worldwide and a device bought on one continent would just work as well on another. Unfortunately, this is not quite the reality.

Countries in Europe, Asia and Africa use the 900 and 1800 MHz band for GSM while UMTS uses the 2100 MHz band. Consequently phones sold in these regions usually support these frequencies. Most phones also support GSM on 1900 MHz which is used in North America but lack the ability for GSM 850 and UMTS 1900 MHz which are also essential for this part of the world. So people visiting North America are always handicapped as in-house and rural coverage is sometimes a problem due to the missing 850 MHz band. UMTS does not work at all…

For people living in North America the situation is vice versa when they travel. Their phones support the 850 MHz band for GSM and the 1900 MHz for GSM and UMTS. These phones usually also support the 1800 MHz band which is one of the frequencies used for GSM in the rest of the world. However 900 MHz GSM and 2100 MHz UMTS is missing…

But hope is on the horizon. Sierra Wireless will launch a Quad Band GSM – Dual Band UMTS data card soon which will support GSM/GPRS/EDGE 850,900,1800 and 1900 as well as UMTS in both the 2100 MHz and 1900 MHz bands. Thus, such worries will be a thing of the past. Let’s hope the technology ends up in mobile phones soon. Nokia for example should have a great interest in this if they want to improve their position in the North America market. Even one of their latest flagship mobile, the N80 does not support both UMTS bands. There’s one for the world market with 2100 MHz UMTS support and another verison with 1900 MHz support for North America. Time to change this!

The question remains why mobile phone manufacturers are so reluctant to produce ‘world band’ phones!? Is the extra hardware cost so much higher than the overhead of producing  and maintaining different hardware and software versions?

A side note: The story is about to be continued. UMTS for the 900 MHz and is already specified and it seems only a matter of time before some countries will start using it. Also, I wonder when UMTS will make it’s appearance in the 850 MHz band.

S60, Python, a GPS receiver, and Google Earth

Googlemaps
Now that most work for the book is done, I have some time to experiment. I recently started to take a closer look at Python for the S60 mobile phone OS and what you can do with it. As I am pretty much into wireless networks, I wanted to have an application that tracks the network coverage where I go for later analysis. I am also quite interested in location based services and a firm believer that these services will only really take off once the GPS receiver is built into the phone. Combining these two interests with a little bit of programming and a recently bought Nokia LD-3W Bluetooth GPS receiver resulted in the following little quality time project:

The Python script I am currently working on queries the GPS receiver, measures the network signal quality and outputs the information in Google Earth format for visualization on the PC. The script is not quite finished yet but the  basic functionality of logging location and signal quality and visualize the data in Google Earth already works. The picture on the left (click to enlarge) shows a result of a 20 minutes test drive. While the line is green, network reception is good. Blue indicates average and red symbolizes a weak signal. Should you be one of the five people on this planet who does similar things and are interested in the source, let me know.

5G New Radio Q&A

All answers have been held as short as possible and require an understanding and study of the corresponding chapter of the book.

Answer 1:

The basic concept of the 5G Non-Standalone architecture is to add a 5G NR cell as a speed booster to an existing LTE radio and core network. It is different from LTE carrier aggregation as the 5G cell acts independently from the LTE part of the connection. Data is transmitted over LTE and 5G NR simultaneously.

Answer 2:

TDD = Time Division Duplex, e.g. used in band n78. Uplink and downlink are transmitted over the same channel. FDD = Frequency Division Duplex, typically used in frequency bands in Europe < 3 GHz. Uplink and Downlink are separated in the frequency domain, i.e. they use different channels. Hence, uplink and downlink are transmitted simultaneously.

Answer 3:

In 5G NSA, data is transmitted over LTE and 5G NR at the same time. Typically the 5G gNB receives the data, splits a apart of it away and forwards it to the LTE part of the connection while it transfers another part itself.

Answer 4:

In the uplink direction LTE and 5G use different frequencies and one transmitter in the UE is required for each channel as data is transferred simultaneously over both legs of the connection in the uplink direction.

Answer 5:

In 5G NR, a UE does not necessarily need to support the full channel bandwidth and can be assigned only a part of the channel on the frequency axis. Also, a network might decide to assign different bandwidth parts to a UE to conserve power with a narrow BWP while only small amounts of data are transferred.

Answer 6:

The CORESET is the Control Region Set, i.e. the control regions the UE has to monitor on the channel for uplink and downlink assignments.

Answer 7:

Dynamic Spectrum Sharing (DSS) can be used to transmit LTE and 5G NR on the same channel. This way, the channel can serve older LTE only mobiles and newer 5G NR mobiles. This is done by transmitting the control channels of LTE and 5G NR in the channel at different times and by using several methods and signaling alignments for 5G NR devices to only notice the 5G transmissions while LTE devices only see the LTE signaling channels and reference signals.

Answer 8:

The LTE eNB and 5G NR gNB have independent schedulers and communicate over the X2 interface which each other. This way, handovers can be made independently as only the X2 connection is switched. In practice it often occurs that the LTE and 5G NR parts are served by different sites. The uplink/downlink data is split/combined at one of the two sites.

Answer 9:

The idea behind the Service Oriented Architecture is to leverage container technology in combination with microservices and stateless communication to build a highly adaptable, configurable and scalable 5G core network.

Answer 10:

5G registration management is performed by the Access Management Function and deals with authentication of subscribers and managing their presence in the network. Session management on the other hand is managed by the Session Management Function and deals with the establishment with user plane bearers between the mobile device and an external network such as the Internet.

Answer 11:

In RRC-Idle state, no active connection exists between the mobile device and the gNB over the air interface. Also, the signaling connection and the user data tunnel to the core network have been removed. In RRC-Inactive state, only the air interface connection is removed while the connection between the gNB and the core network remains in place. This significantly reduces signaling when connectivity needs to be restored.

Answer 12:

The idea of Network Slicing is to have a single end to end network and serve devices with different requirements in different ways. On the air interface, different parts of the channel can use different configurations. One part of the channel could be used for fast Internet access, while another part, that is configured differently could be used for slow but very reliable communication. Other parts of the network can be sliced in a similar manner.

Mobile Monday Paris May 2006 – Pictures and Thoughts

Momoparis
Another Mobile Monday Paris took place last night at the Zen Factory in Paris close to the Place de la République. Again a fabulous event, lots of good discussions with people coming to the event and very interesting presentations. For pictures of the event, see my Flickr picture set of the evening.

First speaker of the evening was Stephane Delbecque of Yahoo France presenting Yahoo’s Connected Life vision. Focus of the presentation was Yahoo’s partnering with the Fifa to bring the football world championship to mobile phones all around the world.

Next, Didier Lesteven of Medialive presented their product which protects digital content on the way from the content provider to the consumer. This is done by their product by stripping out 1% of a media flow which is then protected and sent to the consumer in a secure way.

Afterward Philippe Coup-Jambet of Mobitype gave an overview of their moblogging platform that lets you create your own blog from your mobile phone and also acts as a mobile RSS aggregator. The product is currently in a first trial phase with the public launch expected this summer. The service will be free and is funded by ads which are put into the generated pages. I specifically liked the options of having the top 24h hour posts in one menu as that is missing in my current mobile RSS software.

Presentation number four was by Vincent Berge of the PACA Mobile Center, a new parisian institution in Marseilles that offers a platform for Java developers to test their products on a multitude of different phones.

And finally, Catherine Ramus made sure the evening was not only about technology in itself but also about combining technology with art and her presentation was about how to use 2D bar codes in a museum to get video stream art right on your mobile phone.

Great presentations, thanks very much to the presenters, I really enjoyed the evening! The presentations might end up on the official Mobile Monday France website in a couple of days and you can check them out here.

The Mobile Internet’s 5th birthday

T39j Only 5 years ago, the Internet started to get mobile for me with the launch of the first GPRS networks in Germany and the advent of the first GPRS capable phones. What a different world it was compared to today.

I must have been one of the first GPRS users of the network because at this time and phones and networks were in a shaky beta phase at best. The Ericsson T-39 (first picture on the left) was my first GPRS phone. Equipped with a tiny monochrome display, it could bundle two timeslots to give me a blazing download speed of 25 kbit/s. For web browsing I used a Palm III, also with a monochrome display and one of the first embedded web browsers available at the time. Again, pretty much a beta experience but I loved it.

Yesterday, 5 years later, I was sitting in one of Paris’ best cafés, enjoying good company, an ice cream and discussing mobile lifestyle: Instead of bringing a magazine with me to browse through, my Nokia N70 is always with me ready to take pictures, videos and to connect me to people and the Internet. Here I was, reading the latest news using the Opera browser on the phone, when my eMail client informs me of a new eMail of my publisher in which he informs me that the shipping date for my next book will be July 14th. Great! A little while later, I uploaded some pictures in the background to Flickr which I took in the afternoon while reading some interesting blog entries in the mobile RSS reader at the same time. On the network side, UMTS is much more stable than GPRS was only 5 years ago and data rates have improved from the 25 kbit/s of 5 years ago to 384 kbit/s today.

So what are we in for in 5 years from now? Network speeds will certainly be beyond 8 MBit/s in downlink and 2-3 MBit/s in uplink direction. Prices for mobile data will (hopefully) be at a level to attract the general audience and in combination with the increased bandwidth and services such as video up- and download, LDA applications using the Internet connection and built in GPS receivers will make the application landscape even richer.

The football worldcup – coming to a mobile near you

Yahoo
Not that I am the greatest football fan of all times but a recent entry in Christian’s blog has caught my interest: Yahoo has launched a mobile version of their football world cup coverage site and seems to be the official partner of the Fifa. Check it out at the Fifa web page. There’s a link leading to information how to access the mobile site in the middle of their home page. For those of you not living in one of the countries where they offer a free SMS with the link, point your mobile browser to http://www.fifa.com/e/wc.

There’s lots of content on the mobile site already and you can register for sweets like free SMS alerts on goals when your favourite team is playing. Looks like Yahoo sees this as a good opportunity to get people interested in the mobile web and of course what Yahoo is doing in this domain. With all the media hype around the world cup and people being so excited I tend to agree.

I haven’t seen too many mobile offerings for the last Winter Olympics (but I have to admit I didn’t really look for them). So is this the first time such a world wide event also get’s some world wide and free (to what an extend we will see) coverage on the mobile web? I wished there was a similar offer to keep track of what’s going on in Formula 1.

So here we are right in the battle between content providers such as Yahoo and mobile operators to get the attention of mobile users. Let’s see who does a better job. I’ve quickly checked if my home operator (Vodafone Germany) is offering anything similar and how it compares. Looks like they also offer free Goal alerts via SMS but beyond that I didn’t see much. Let’s see how it develops.

Global GSM and European UMTS Rollout Progress

Europecoverage2small
While having visited a colleague in his office yesterday I saw an interesting global map on the wall showing the current global GSM rollout status. The map was different from all other maps I’ve previously seen as countries which adopted GSM technology were not completely filled with a color marking them as "covered". Instead, the map showed the detailed coverage status in each country. The map together with even more detailed continental maps can be found at www.coveragemaps.com.

Here are some of my personal observations which quite surprised me:

The U.S.: When I last checked two or three years ago, GSM coverage in the U.S. was patchy at best. I still remember checking on Texas and finding an almost empty map. Quite a different picture now.

South America: Except for the rain forests, the continent is well covered with GSM now.

3G Rollout in Europe: The map gives quite a mixed picture varying from country to country. While the UMTS rollout seems to be quite advanced in some countries, there are lots of ‘GSM’ only areas in other countries:

Germany, U.K., Ireland, Sweden, Austria: These countries seem to be pretty well covered with 3G already. I can confirm this for Germany at least where Vodafone has dedicated coverage even in small villages (<5000 people). Nevertheless, it’s still patchy on the countryside. Same goes for Austria.

France: Quite disappointing, the green "GSM only" areas are still substantial. The map seems to be quite accurate as it compares quite well to the official map of Orange, France that can be found here.

Italy: This one is strange, only a couple of yellow "UMTS" patches here and there. But I don’t think the data is up to date in this case as Italy was one of the first countries deploying UMTS and the current Wikipedia entry on Vodafone Italy says that 70% of the population are now covered by UMTS. I tried to find coverage maps on tim.it and vodafone.it but it didn’t find any. Is my Italian so bad? If somebody sees maps, please tell me. The only info I found was on tim.it. On this page you can select you city and a database lookup reveals if there is coverage or not. No maps though… However, many cities I tried which were not covered on the map came back as UMTS covered.

Finland: Another strange case. The land of Nokia, the land of mobile phones and almost no UMTS areas on the map!? Can this really be!? Some of my Finnish readers, please check and comment. A link to a coverage map of a Finnish operator would also be nice…

Offshore: Also take a closer look at the GSM coverage spots in the North sea. They seem to be drilling platforms! Cool!

How the Nokia N80 handles WLAN

Nokian80
Up until now not much is known about how applications on the N80 will be able to use the built in wireless LAN capabilities. When checking the Nokia website today, I saw that the N80 manual can now be downloaded from this link. So I rushed to take a closer look to see if it sheds some light on this topic. And indeed it does!

Basically, the manual says that the use of WLAN is transparent for an application on the phone. Just like for a data connection via GPRS and UMTS, a new access point profile can be created to enter the settings of how to communicate via a WLAN network. Several profiles can be created if different WLAN networks are used, e.g. at home, at work and in public. In an application, a WLAN profile is selected from the already known list of access points that pops up when an application wants to access the network and no default access point has been configured in the application. Instead of only GPRS and UMTS connections the list can now also contain WLAN connections. Quite elegant, it’s completely transparent!

The manual also says that one access point profile can be used by several applications simultaneously. Again, this already works today for GPRS and UMTS connections when two programs such as the browser and the eMail program are used to communicate with the network at the same time.

And here comes the most important part concerning the simultaneous use of the phone in the GSM/UMTS network and WLAN. I quote from the manual on page 14: "You can use wireless LAN during a voice call or when packet data is active". That’s really great news and means that while at home, for example, the phone can be used for incoming (and outgoing) cellular calls simultaneously with an activated VoIP client (SIP, Skype…) via wireless lan.

It looks like my dream of a unified phone at home is close to becoming a reality! I can hardly wait using the Skype client on the phone to call friends while lying on the couch while not missing incoming cellular calls. Hurry up, Skype! Oh, and by the way, don’t forget to support the built in camera 🙂

SIP Update 1: Jukka left a comment that there’s already a built in SIP client in the N80. I completely missed that when browsing for the wireless LAN details in the manual. Indeed, the manual shortly describes that there’s a new menu where to enter the settings for the SIP client and that SIP addresses can now be part of a phone book entry. Would be interesting what can be configured but the manual doesn’t say. So Skype’s got another reason for hurrying up, the competition is already there!

SIP Update 2: The topic keeps developing: Too bad I don’t have an N80 yet so I have to rely on the sparse technical information in the manual. After some more digging I found out that the included SIP client seems to be closely tied into the standard voice call feature. The SIP functionality can be used during a standard voice call to establish a video sharing session via SIP in a packet bearer. While the feature is quite nice it’s not yet what I need to call someboday via VoIP over the WLAN functionality while being at home.

SIP Update 3: A reader has noticed that Nokia is about to release a major software update for the N80 called the N80i, or Internet Edition, whith some additional VoIP capabilities: From the press release: "The VoIP framework (based on the SIP protocol) is integrated into the
Nokia user interface, and the Nokia N80 Internet Edition is allows for
downloading compatible third party internet call applications.". One step closer but we still need a 3rd party client.


Communication Systems for the Mobile Information Society: It’s Almost Ready

07052006079_1
I am always amazed of how much fine tuning goes into the production of a book. I delivered the manuscript at the end of January and since then it has been proof-read, the layout has been done and I’ve received the page proofs for final verification. Almost ready for production now. This weekend I’ve sent the final corrections of the page proofs back to the company that does the layout. For those of you who are curious, the book is already listed at Amazon and the listing contains the back cover text which gives some details about the content. Their publishing date of September is a little bit conservative… It should be out much sooner. I’ll keep you posted.