Feeds

Cutting the cord: future mobile broadband tech

How internet on the go is going to get much faster

7 Elements of Radically Simple OS Migration

Each user's data, be it compressed voice or IP packets, is multiplied by what's called a 'spreading code' which is unique to that user. The receiving basestation gets the combined signals from every user on the frequency, but dividing that received data by the user's spreading code reproduces the original data for that specific user. Applying different spreading codes to the same received data can, in W-CDMA, reproduce the communication for almost 200 voice calls - depending on the codecs being used.

NEC 338 3G phone

Did anyone really make video calls?

Voice still takes precedence, but W-CDMA can support data rates of up to 384Kb/s with minimal connection times. Slower rates are also possible, as well as maintaining several connections at the same time. When 3G data services were developed, it was commonly thought that users would want multiple data connections billed at different rates: a slow connection for e-mail notifications might be free to use, a slightly-faster one for instant messaging could be always connected as part of a premium tariff, while the full 384Kb/s would be available on demand for video calling and the like.

But it's not just video calling that punters proved reluctant to do - not enough were downloading music from the network operators, or subscribing to video streaming services, or really using any of the whiz-bang services by which the operators had justified the billions spent on the licences. Unable to understand the reluctance of users the engineers decided that if only the connections were a little faster then the mobile internet would finally happen, so set about squeezing a little more speed out of the W-CDMA standard.

It's all in the angles - OFDM

OFDM (Orthogonal Frequency Division Multiplexing) isn't a new technique, or one unique to the cellular industry: it's also used by the Wi-Fi as well as ADSL broadband and DAB radio, but it is worth understanding as it provides remarkable facility as long as one has a wide enough band in which to use it.

The main problem OFDM solves is one of timing. A transmitter sends a chunk of data, followed by another one: assuming the chunks arrive sequentially then everything is fine, but if the first chunk bounces off a wall and thus arrives slightly later then it can interfere with the second one as their arrivals coincide. Obviously, this problem can be addressed by leaving a timing gap between the chunks, but OFDM instead puts them in different frequencies so the second can be sent immediately after the first.

That requires a fast radio and generally contiguous spectrum - though OFDM can be used in non-contiguous blocks, it's just more difficult. Orthogonal in this context means 'discrete' or 'separate' rather than anything to do with angles or Greeks.

Build a business case: developing custom apps

More from The Register

next story
Nice computers don’t need to go to the toilet, says Barclays
Bad computers might ask if you are Sarah Connor
4K video on terrestrial TV? Not if the WRC shares frequencies to mobiles
Have your say with Ofcom now, before Freeview becomes Feeview
PEAK LANDFILL: Why tablet gloom is good news for Windows users
Sinofsky's hybrid strategy looks dafter than ever
YES, iPhones ARE getting slower with each new release of iOS
Old hardware doesn't get any faster with new software
You didn't get the MeMO? Asus Pad 7 Android tab is ... not bad
Really, er, stands out among cheapie 7-inchers
Apple winks at parents: C'mon, get your kid a tweaked Macbook Pro
Cheapest models given new processors, more RAM
VMware builds product executables on 50 Mac Minis
And goes to the Genius Bar for support
Leaked Windows Phone 8.1 Update specs tease details of Nokia's next mobes
New screen sizes, dual SIMs, voice over LTE, and more
Microsoft stands on shore as tablet-laden boat sails away
Brit buyers still not falling for Windows' charms
prev story

Whitepapers

7 Elements of Radically Simple OS Migration
Avoid the typical headaches of OS migration during your next project by learning about 7 elements of radically simple OS migration.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Solving today's distributed Big Data backup challenges
Enable IT efficiency and allow a firm to access and reuse corporate information for competitive advantage, ultimately changing business outcomes.
A new approach to endpoint data protection
What is the best way to ensure comprehensive visibility, management, and control of information on both company-owned and employee-owned devices?