Welcome to the less caring, less conformist generation
Both WiMax and LTE make use of ODFM and Mimo. LTE only uses ODFM for the downlink (to the handset), but its implementation of Mimo is more advanced than WiMax and the technology is largely irreverent at this stage: it comes down to which technology is going to achieve the economy of scale necessary if it is to dominate.
3GPP Long-Term Evolution Timeline
Over the last few years, a war has been fought, largely between the companies owning the patents on the different technologies. Intel heavily invested in WiMax and has been fighting it out with Qualcomm, the latter's CMDA interests incorporated into LTE. Nokia has weighed in on the LTE site - when not fighting Qualcomm over ownership of CDMA. Intel's lack of experience in the mobile industry hasn't helped the WiMax cause, and LTE was specifically designed to appeal to network operators - Ericsson estimates that a WiMax network at 2.6GHz would need between 1.7 to 2.5 times as many basestations as a 3G network on the same frequency, figures which mean lot to network operators.
WiMax had a time advantage - the first version of the standard was completed back in 2005, though when comparing with the competition the WiMax Forum tends to use the recently ratified release 1.5 (802.16e revision 2) while ignoring the more-recently-published versions of HSPA. But that lead was eroded as regulators struggled to embody a new philosophy that has changed the way that radio spectrum is distributed and used.
Mimo, your Mo, everybody's mo
Mimo (Multiple input, multiple output), is basically the idea of having several aerials receiving different signals simultaneously, either to increase bandwidth, reliability or both. The technique is old news to the Wi-Fi crowd, but still leading edge in cellular.
In 4G networks, Mimo is used for two purposes: to create directional signals, and to increase the bandwidth available by sending multiple signals at the same time to be picked up by separate antennae. LTE, for example, uses the former technique to connect users at the edge of the cell, and the latter to provide greater bandwidth to those nearer the middle, at least in theory.
Huawei's E182: boosting HSPA to HSPA+ with Mimo
The problem with having multiple antennae is that they need to be physically separated, generally by at least quarter the wavelength being used. For 2.6GHz that's easy enough - a wavelength of around 12cm makes for aerials at least 3cm apart, ideally 6cm. But reduce the frequency into the digital dividend space and things get more crowded. A transmission at 600MHz has a wavelength of nearly 50cm, putting our antennae more than 12cm apart, which is tricky on a modern handset.
On the basestation things are easier, but only a little. A Mimo basestation can operate with antennae half a wavelength apart, but several times the wavelength works a lot better - up to ten wavelengths isn't considered excessive. That may be practical in some circumstances, though it does make a 600MHz basestation 5m wide.
COMMENTS
OFDM
In the process of trying to make OFDM more palatable to a non-comms audience, you seem to have missed the real advantage of the technique. The real beauty of OFDM is the flexibility given by so many orthogonal low-bandwidth sub-carriers: you can avoid the problem of frequency-selective fading for one user (mitigating their bad channel) by moving their allocation in the spectrum. This leads to much more efficient usage of spectrum, and better channels for all. It is excellent at adapting to nasty channel conditions in slowly-changing channels*.
I'm not really sure what you're getting at with regards to "solving" the problem of "timing". If you're referring to inter-symbol interference, which is indeed a concern, then OFDM doesn't directly solve this by "putting [chunks] in different frequencies" - but what it does do is ensure that the symbol rate on each individual component frequency is low enough that ISI can be mitigated easily. But if you're referring to interleaving, which does indeed spread "chunks" of data amongst frequencies, then that helps solve a different problem: the issue of losing bursts of data in frequency-specific fades.
On the down side, OFDM really isn't good in channels with a great deal of doppler shift (since it breaks the orthogonality between the sub-carriers) - making it non-ideal for use in fast-moving vehicles, for instance, without specific counter-measures.
8390? shouldnt that be 8310?
Good article, but as this article seems to have a UK slant to it.. the 8310 should have been the phone that was mentioned as being the first with GPRS in the UK. The 8390 was not even the first phone in the US with GPRS, a motorola timeport was, if i remember correctly.
Jobs - because the iPhone wasnt a world first in any area.
"mobile data is all about ..."
That's the 64billion dollar question, isn't it.
Is it about seeing the same internet as at home (or in the office), when you're on the move (nb on the move, *not* just away from base but stationary at a WiFi hotspot).
Or is it about the mobile web, about some selection of significant websites recognising that there are going to be as many folk viewing them on "mobile internet devices" (phones, PDAs, maybe netbooks) as there are on PCs, and that their website designs should reflect that (eg no Flash).
It isn't about "m-commerce" yet, or about "location dependent services", and folks have been trying that for a decade or so. Mind you, Google has recently changed the market rules, as it sometimes does, with Google Maps for Mobile and the things you can do with that.
Yahoo nearly works on my S60 mobile in Opera Mini. BBC news has a "low graphics" version too. Google Maps for Mobile is fantastic, though without a GPS it sometimes gets confused (but that's probably not Google's fault).
But not everyone does so well. Obviously anyone designing in Flash has wasted their time even more than usual. Some sites that you would imagine might be of particular interest to those out and about are so full of big-screen rubbish and scripts and so on that they are useless on a small screen device, mobile or otherwise. Classic examples would include weather forecasts from the Met Office and traffic reports from the Highways Agency.
http://www.metoffice.gov.uk/weather/uk/se/reading_forecast_weather.html
http://www.trafficengland.com
Madness.
So, what exactly is the killer app for mobile broadband? How is it going to make money for the cellcos, so they can pay for all that extra bandwidth to all those new cells?
I know, we could do location-dependent downloaded-on-demand high-definition video ringtone subscription service. Yeah, that'd work. Where's the Dragon's Den number.
Well? You got any better ideas?
Handset or PC?
To me the main reason that data on 2G/3G etc. has not really taken off is that most content is not suitable for a phone handset.
When WAP first came out, most web content was too complex and there were attempts to produce WAP portals which would offer cut down content suitable for the handsets.
At that point most web content would have displayed well on my EEE PC (if it had existed then).
Now content is so rich and so loaded with fancy video and special effects that I struggle on my EEE PC and my older portable to view the website in the way that the cutting edge design intended.
Nice on my new 1440 * 900 Dell portable, though :-)
Not much good on a phone handset :-(
For me, mobile data is all about freeing portable PCs from fixed ADSL/cable connections.
You can get the rich content you have come to expect when you are away from your cosy nest.
Now if only the coverage, reliability, bandwidth etc. etc. wasn't totally crap. (Speaking as a Virgin customer).
If I want to talk to someone or send a text message I use my phone.
For getting serious data off t'Internet I use a PC.
Then again, I am from the keyboard generation and can't think through my thumbs.
Cheers
Dave R
