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In today's 3G networks, voice calls are often in the so called “soft handover state”, which means that the radio network controller sends and receives the data for a voice call to and from several base stations simultaneously. The mobile then receives the voice call data stream from all three cells simultaneously and combines the received signals. While this wastes some bandwidth on the backhaul, these soft handovers often help to reach mobiles at the cell edge, which receive one or more cells with a similar strength.

For HSPA data transmissions, however, the soft handover is not used as the base stations autonomously decide when to schedule data on the air interface and thus, it is pretty difficult to synchronize the transmission over the air interface of several cells. In LTE, such a direct cooperation between cells is also not foreseen for the moment, even though there might be some benefits for mobiles at the cell edge. For LTE Advanced, however, people seem to have started thinking about it again. Instead of sending the same data stream over two or more cells, however, they are thinking about a cooperative MIMO scheme, i.e. each base station sends a different data stream and the mobile then analyses each data stream separately. The result would be a higher throughput for that mobile.

As Moray Rumney points out in his recent book, though, such a cooperative MIMO scheme would be quite challenging to implement in the network. First, it would put quite a demand on backhaul capacity and second, data would have to be exchanged between the base station with a delay of a millisecond or less. O.k., it is still some years away and technology advances, but I tend to agree with him, that's quite challenging to do. What do you think?

Lately I get the impression fewer people use clamshell phones than in the past. Even in the US it seems to me that when I was last there I saw more people with Blackberries running around and happily typing away on the keyboard than people still using a clamshell phone. So why? Could it be that the clamshell format is great for voice calls, i.e. quite sexy to open it up, but does not lend itself very well to text or web based applications? The smaller screen of the clamshell vs. sliders and the act of opening up the phone to check for messages, send a quick sms, e-mail or surf the web might just be that tiny little bit too much these days!? What do you think, what are your observations?

Recently, I had an email conversation with a reader and he sent me a list of mobile phones he had in the past. Interesting memories coming up. I doubt my list is equally long but I think it is time to make my own so I won't forget. Here we go:

• I started with a Bosch 738 (I am German, the French will get the irony)
• A Siemens S25 (my first color phone)
• A Ericsson T39 (my first GPRS phone (!), could only do static assignment, only worked in one network)
• A Siemens S45i (GPRS worked well after a couple of software upgrades)
• A Siemens S55 (browser, color screen, a couple of hundred KB of flash memory with file system!)
• A Sony-Ericsson V800 (my first UMTS phone)
• A Nokia 6630 (only used as a modem at the time)
• A Nokia 6680 (First phone on which I discovered the power of S60)
  
• A Nokia N70 (Natural evolution from the 6680)
• A Nokia N93 (Bought because of the camera and the twist) 
• A Motorola V3xx (initially used as an HSPA modem, today also as backup phone)
• A Nokia N800 Internet tablet (o.k. not quite a mobile phone)
• A Nokia N95 (my main phone today in 2009, bought because, well, because of everything 🙂
• A Nokia N82
• A Nokia 5000 (low end with color screen, used as phone and to test apps on an entry level platform)

And in addition:

• I had a Palm 3, and two HP PDA's, discontinued to use them when I bought the N70, as I could do all the calendar stuff, etc. on the mobile phone
• A Sierra Wireless 850 1.8 MBit/s cat 12 HSDPA PC-card modem
• 2x Huawei E220 3G USB dongles (3.6 MBit/s cat 6 HSDPA) for Internet access. In use today. They might be a bit clunky by today's standards, but they just work in all networks I have used so far, which can't be said of other 3G sticks I tried.

There we go, the list is already longer than I thought 🙂

Over the past days there have been reports in the press that Vodafone Germany will trial LTE in the 800 MHz digital dividend band to collect experience how this frequency band can be used for rural broadband Internet coverage. The reports also mentioned that a TV station (the WDR) will also take part in the trial. A TV station?

Why, I wondered at first, as all but Unstrung did not go into the details of why a TV station is part of the trial. So, according to Unstrung, the TV station is part of the trial as they are interested, or a bit worried, that using spectrum in the 800 MHz band for broadband Internet could have an impact on their TV broadcasts in an adjacent band. Further, wireless microphones are using the digital dividend band today and it seems it is not quite clear of what can be done about that in the future (see here and here).

So the outcome of this part of the trial will be quite important to figure out if or how all of the 72 MHz foreseen to be assigned in the 800 MHz band for mobile broadband systems can be used without generating too much interference for TV broadcasts. An interesting topic to follow.

And another follow up post on the University of Oxford's Future Technology Conference: During on of the many "socializing breaks" I met Eric Seuret of 3SMobile and he told me about the crop insurance via SMS application for farmers in Kenya he has developed for Syngenta, a large global agriculture company. The concept is so elegant, simple and has the potential to improve the lives of many people, so I asked Eric to send me some more details about how the service works. Here are the details:

The weather insurance solution via SMS helps protect small holder farmers against the risk of drought.  When a farmer purchases certain Syngenta seeds and crop protection products he obtains special insurance stickers.  When he has collected a certain number of stickers he gets an ID number which entitles him to 1 acre of free weather insurance for that season. To obtain the insurance he does not need to fill out any forms or contracts.  All he needs need to do is SMS a unique insurance code ID to a local number. The system then verifies that the insurance code is valid and confirms the farmer's insurance status.  If the farmer has a larger plot of land he can obtain multiple cards and insurance policies.

Throughout the course of the year the farmer is kept informed of major weather issues that are related to the policy via SMS.  At the end of the season the historical weather data is used to determine which farmers are entitled to a payout based on their region.  In the case of a payout the farmer is notified via SMS and they can go to the stockist to obtain the payout.

It is the first time that insurance has been made available to small holder farmers in Kenya with 1 acre or less of land.  This has only been possible through the use of mobile technologies were the solution finally became cost effective.  Mobile phones were used to simplify the administration, reduce costs, enable immediate registrations, and to help form a direct link to the end customer. In many cases the mobile phone represent the only way to reach the farmers without physically visiting the remote villages.  The innovative solution is currently running as a pilot project and is so far proving to be very successful.

The insurance concept and solution was designed by Rose Goslinga and Fritz Brugger for the Syngenta Foundation for Sustainable Development and developed by Eric Seuret.

If you've been waiting after my report on the ForumOxford Future Technologies Conference 2009 for the presentations of the other speakers, they are now online and can be found here. A little bit hidden but definitely worth a look is Jonathan Marks' video summary of the event. Not much more to say, so head over and enjoy!

Over the weekend, I wanted to take a closer look at the 3GPP Earthquake and Tsunami Warning System (ETWS) for GSM, UTMS and LTE. I was expecting to find proper stage 1, 2 and 3 documents in place by now so implementations could follow soon. It turns that of the three documents, only stage 1 (3GPP TS 22.168) has made it so far into Release 8. However, it seems that the specification might have been withdrawn at SP-43 in Biarritz in March 2009. 

The same applies for the stage 2 documentation 3GPP TS 23.168, it's current state is "withdrawn". There is a pointer to Technical Report (not a specification!) TR 23.828 which gives an overview of the different options analyzed and the proposal at the end to go for solution 5. Solution 5 would be to send a first warning to the mobiles via a special paging message with further details right afterwards in a cell broadcast message. For GSM mobiles already engaged in a voice call, the BTS would create a special SMS and sent it over the slow associated signaling channel while the call is in progress. In UMTS, paging messages can also be received during a call. What's not mentioned is how mobiles currently having a GPRS TBF established would receive the notification as there is no associated circuit switched signaling channel and pagings would not be received over the paging channel. But for the moment, that is beside the pont, since both stage 1 and stage 2 of the specification was withdrawn.

However, there is a link to 3GPP TS 22.268, a stage 1 specification for a much more generalized public warning system (PWS). No stage 2 specification exists so far, so this one is also at the beginning. It's an interesting document as it shows how much time there is to warn the public about an earthquake or a tsunami. Very challenging!

I am a bit puzzled!? Looks like ETWS was already quite well on it's way but now seems to be suddenly stopped? Did it fall short of the requirements? If you know more, please leave a comment below.

O.k., I'll play along with Nokia marketing for the N97 today for three reasons:

• I can't wait for the N97 to be launched so I can finally get one after months and months of waiting.
• I hope they made good use of the time and have a usable firmware version by now.
• I like the N97 "making of" video embedded below. O.k., it's marketing, but well done and it reflects my passion for mobile communication.

Nuff said, here's the video, switch to HD, full screen and enjoy!

Over at TelcomTV, a video series has been started on the impact of the Information and Telecommunication Industry on CO2 emissions, energy consumption and how to reduce the impact as we go forward. One episode is published per week together with lots of background information. A very interesting project sponsored by Ericsson and Juniper and I'll be surely watching it over the coming weeks. There's also an RSS feed on the page so you don't have to remember going back to the page once a week for the latest update.

When do you know that a technology has not only reached the main stream but that virtually everyone uses it? I think that stage is reached when not only kids are "doing it" but the 60+ generation as well.

Only a couple of years ago my mother was saying "yes, I have a mobile phone but I don't like it and it's only lying around at home and dust is settling on it". Now in 2009, she's sending me SMS messages on a regular basis and even admits that it is fun. (!?)

Why this change of heart I asked her? "Well", she said, "all my friends send me text messages these days, so I do it too now and it's great fun". Incredible, generation 60+ is using SMS now and they like it. And all of that despite the horrible user interface of a mobile phone, especially for people who keep insisting that the TV remote control is too complicated. I am amazed!