I didn’t know the IETF had a sense of humor! RFC 1149’s title is ‘A Standard for the Transmission of IP Datagrams on Avian Carriers’. Definitely worth a read. And it looks like a quality of service extension was added with RFC 2549 ‘IP over Avian Carriers with Quality of Service’. 🙂
Nokia ships first UTMS/HSPA 900 Phone
Recently, Finland’s Elisa has started the operation of one of the first UMTS/HSPA networks in the 900 MHz frequency band. While I heard this news some time ago I never quite figured out which mobile devices they had for the product launch. Most mobile devices shipped in Europe only support UMTS/HSPA on the 2100 MHz band. One of the few exceptions is Sony-Ericsson with their K850i, which also support U.S. frequency bands. But even this model does not support the 900 MHz band. Now Wikipedia reveals the secret: Elisa offers the Nokia 6121 classic for use in their network. As confirmed by this page on the Nokia web site it supports 3.5G on both the 2100 MHz and 900 MHz band. An encouraging first step! Keep going Nokia!
Carnival of the Mobilists #100
The Carnvial of the Mobilists celebrates its 100th edition today over at Abhishek Tiwari’s blog today. As always great insight from this planet’s top bloggers on wireless. BTW: Did you know Android applications will be written in Java? It was quite a surprise for me. For more, head over and discover.
Next week it will be my pleasure to host the carnival on mobilesociety. So keep these entries coming!
Will Fixed/Wireless Convergence Push IMS?
Despite its multimedia capabilities the IP Multimedia Subsystem (IMS) hasn’t yet gotten a lot of opportunities to show its capabilities in wireless networks. One of the reasons for this is that current circuit switched mobile voice telephony works well and meets user expectations. Things, however, are improving for IMS.
With the introduction of the iPhone, more and more people are getting aware of multimedia and Internet capabilities of mobile devices. Thus, it might well be possible that multimedia enriched voice calls might also soon appear on the radar screen of users. On the network side many operators are upgrading their current 3G networks to 3.5G and with the first WiMAX networks rolled out now and LTE on the horizon there is sufficient bandwidth for such services. Additionally, WiMAX and LTE networks no longer have a circuit switched part and operators need a solution such as the IMS to be able to offer conversational services over their next generation networks. It thus seems inevitable, that the IMS will have a bright future.
In practice, however, things will be a bit more difficult since third party VoIP service providers such as Skype, Vonage and others could try to take a piece of the wireless market in a similar way as in fixed line networks today. After all, the application layer does not care whether IP packets traverse a DSL line or the air interface of a wireless network as long as there is enough bandwidth. From my own experience, SIP and proprietary VoIP services such as Skype work well over 3.5G wireless networks and even Skype video calls have excellent video quality in both directions.
Network operator based IMS systems, however, have a number of advantages over voice services provided by third parties if the play their cards right:
Network operators today sell both a mobile device and voice service. This means that the service works out of the box, no configuration required by the user. With pre-installed and pre-configured IMS applications such as voice, video calling, presence, etc. they have a head start over third party services for which applications have to be installed on mobile devices.
The IMS is also able to request a certain bandwidth for a session from the transport layer. In case there is congestion anywhere in the network, it will be made sure that multimedia sessions are not impacted.
The third advantage, which I think is a major one, is that IMS gives network operators with both fixed line (think DSL, cable) and wireless assets (think HSPA, WiMAX and LTE) the opportunity to converge their voice + multimedia service offerings both in the network and from the users point of view.
In the fixed line world the transition from analog telephony to VoIP over DSL or cable is already in full swing. The incentive for the user to switch to VoIP is usually a lower price for a combined voice service and Internet access over DSL or cable. When combined with mobile voice + Internet access, network operators can offer their clients Internet access + voice (and multimedia) telephony both at home, in the office or while roaming outside with a single device and a single telephone number.
The IMS also allows to have many devices registered to the same telephone number. This is great since at home it might be more convenient to use a dedicated phone, a notebook or even an IMS capable and connected television set to make a voice or video call.
With Voice Call Continuity (VCC) there is even the possibility that a mobile device automatically switches to Wifi when the user returns home or to his office thus reducing the load on the cellular network. Switching to Wifi at home also solves the issue of 3G/4G in-house coverage which in many regions of the world is inferior to 2G coverage due to the use of higher frequency bands.
And finally, the IMS has the capabilities to transfer a voice call from one device to the other. This is quite interesting in scenarios in which the user returns home and then transfers an ongoing voice call from his mobile phone to a television set and adding a live video stream to the call in the process.
It’s clear that getting all of this right is not a trivial task. But if network operators want to retain their role as a service provider they have to go beyond what third party service providers could offer over a bit pipe.
As always, thoughts and comments are welcome!
Prepaid Mobile Internet Access in Switzerland
Switzerland has had some pretty good tariffs for mobile Internet access via mobile networks for a while now but only for postpaid customers. Looks like times are slowly changing there, too. Sunrise and Aldi Switzerland (using the Sunrise network) now at least offer data tariffs with prices that should allow mobile eMail and web surfing via the mobile phone browser.
Sunrise and Aldi Switzerland ask for 0.10 Swiss Francs per 20 kb block which is 5 Swiss Francs per MB or about 2.90 Euros. Well, way to go, but it’s a start. But I definitely would not use it with a notebook.
When roaming the price per 20kb block is 0.30 Swiss Francs per 20 kb block for all roaming countries according to the price list of Sunrise. That’s 15 Swiss Francs per MB or about 8.90 Euros. Not really on the cheap side but still cheaper than many other roaming alternatives for countries for which you don’t have a SIM and don’t want to spend a full 15 Euros for a 24 hour Vodafone Germany Websession.
I had a look on the Aldi Switzerland homepage for the details. To get a SIM card a registration form has to be downloaded, filled out and taken to one of the Aldi supermarkets when buying a SIM card together with your passport. Activation of the SIM card then takes around 24 hours. I wonder if things work quicker when going to a Sunrise shop!?
One more note: Orangeclick also offers mobile Internet access but prices are not competitive unless you subscribe to a 5 Swiss Francs add on which is deducted from the prepaid account once a month. This gives you 2MB worth of data and a price of 2.5 euros per megabyte afterwards.
More information on prepaid wireless Internet access via cellular networks for many countries can be found here.
I-WLAN for IMS access over Wifi
I’ve taken a look at IMS lately and ways to access the IMS from non 3GPP networks such as Wifi hotspots and Wifi at home. Looks like 3GPP TS 23.234 and TS 33.234 contains everything required for the purpose. The first major building block of I-WLAN (Wireless Local Area Network interworking) is how the subscriber database of a 2G/3G network can be used to authenticate Wifi users that have a device with built in GSM/UMTS SIM card. For this purpose EAP/AKA or EAP/SIM is used. For EAP-SIM I’ve written a blog entry some time ago. The standard also foresees methods for the access point to deliver billing information to the 3GPP network.
What I didn’t realize at that time was that the second building block in those two documents is a method to establish an IPSec encryption tunnel between a mobile device and a gateway between an external network (e.g. the Internet) and the 3GPP core network which hosts an IMS. This gateway is called the Packet Data Gateway (PDG). The standard even says that the IPsec tunnel setup can be used without the above mentioned EAP-SIM authentication step. That’s good news as the EAP-SIM authentication requires support of the Wifi Access point while the tunnel establishment is transparent to the Wifi access point.
So let’s see maybe we’ll see 3G+/Wifi IMS devices with the ability to establish an IPSec tunnel over Wifi to the IMS of their wireless operator. Great stuff for mobile operators with DSL assets.
Nokia and Finland – The Land of the Mobile Millionaires
While driving back home from a weekend trip I listened to this very interesting BBC world service podcast on Nokia, Finland and the land of the mobile millionaires (of course on a Nokia mobile phone…). A very entertaining 22 minutes story about a BBC reporter’s trip to Finland to discover how Nokia has shaped the people, the country and how they have shaped Nokia. So if you are interested in Nokia, rubber boots, Finland, mobiles or a combination thereof, it’s worth to listen in.
UMTS pushes into the “Deep-Ruralness” of Austria
It’s been a year since I was last in what I would call a ‘deep rural’ spot in Austria in a little town in the region of Oberösterreich with around 2500 people living there and nothing but countryside and cows around. In the past months there have been press reports by a number of Austrian UMTS operators that they will now also start covering the Austrian countryside with UMTS. I didn’t give it much thought at the time as words in press statements usually have to be taken with a grain of salt.
Looks like, however, words have been followed by action. This time I was surprised when I saw UMTS networks of A1 and ‘3’ on my network selection dialog. Most excellent since A1/Mobilkom is the roaming partner of Vodafone Germany so I can use their Websessions here! A quick test revealed data rates of 1.2 MBit/s in downlink. Far below the capabilities of HSDPA but likely due to a limited backhaul. Never mind, it will do nicely.
First Signs of HSPA+ in the Standards
It looks like 3GPP member companies are moving quickly to standardize data rate enhancements for current 3.5G UMTS / HSPA networks as promised in diverse marketing slides floating around at conferences. The two main ideas to further increase transmission speeds are to use a higher modulation scheme (64QAM) and MIMO (Multiple Input Multiple Output) to send several data streams via different spacial paths simultaneously.
3GPP TS 25.306-800 has an interesting table (table 5.1a) that specifies current and future HSPA terminal categories for downlink. Today, mobile devices typically use on of the following terminal categories:
- Category 12: Speeds up to 1.8 MBit/s (first HSDPA cards for notebooks)
- Category 6: Speeds up to 3.6 MBit/s (most HSDPA cards sold for notebooks in 2007 and pretty much all mobile phones supporting HSDPA)
- Category 7/8: Speeds up to 7.2 MBit/s (the latest HSDPA cards for notebooks)
I’ve tried all three types of HSDPA cards in practice and could reach around 1.4 MBit/s with a Cat-12 device, around 2.5 MBit/s with a Cat-6 device and around 4.2 MBit/s with a Cat-7/8 device.
For HSPA+, Release 8 of the 3GPP standards now introduce terminal categories 13 to 18. In Category 18, a terminal can receive up to 27952 Bits per 2ms TTI per MIMO channel (I assume). That would result in a speed of around 28 MBit/s. Interesting to see that in 2×2 MIMO mode, only 16QAM and not 64QAM is used. Category 14 terminals can receive 42.192 bits per 2ms TTI in non-MIMO mode. That’s still an impressive 21 MBit/s, even without MIMO.
In order not to get too excited about these numbers have a close look at the physical realities of a radio channel in the real world. Even though specified on paper such speeds are only achievable under the very best of radio conditions with little to no interference from neighboring cells. Having said that I nevertheless believe that we will see nice speed enhancements in practice. I am looking forward to see just how much!
More Uses For Curbside VDSL cabinets
A couple of days ago I have rumbled a bit on the big street side cabinets that need to be put into place for VDSL every couple of hundred meters. Recently I have received an interesting eMail from one of you saying that they might just be perfect to put Wifi hotspots inside. Hm, what an interesting idea! At the size of those cabinets there should be some space left for a little access point. And backhaul is definitely not a problem with those fiber cables in the ground.
Well, why not put an HSDPA or, later on, an LTE microcell into these cabinets to increase cellular capacity in high traffic areas!? Again, no backhaul and power problem, as both are available in the cabinet. As microcells only use little transmit power and only cover small areas a little omni-directional antenna discretely put on a nearby pole or wall will do. Interesting possibilites for converged fixed/wireless network operators of the future!