The extended post-3G roadmap

14 Feb 2006

With 3G barely out of the gate and still evolving, the cellular industry is already plotting a course toward 4G. But while it looks linear and neat on a PowerPoint slide, the details are mind-bogglingly complex - which is why the first of the standards won't be ready until 2008 and 4G itself won't arrive before the end of the decade

It was this time last year that NTT DoCoMo and 26 other companies announced plans to sit down and start seriously working on the next evolutionary steps for W-CDMA. Until that point, of course, everyone knew that the next 'stage' for W-CDMA was HSDPA. Beyond that, however, was some vaguely defined cloud referred to generically as '4G'.

NTT DoCoMo and friends didn't help matters by describing their project as 'Super 3G' - which would feature data rates and technologies often associated with 4G, but wouldn't actually be 4G. The group did say, however, that it would be keeping the 3GPP in the loop on its work. The 3GPP, meanwhile, has not been idle, and now 'Super 3G' finally has an official name.

This is it: UMTS Terrestrial Radio Access Node Long Term Evolution (UTRAN LTE). Not exactly snappy, which may be why some vendors have shortened it in their PowerPoint slides to LTE, or 'Evolved UMTS', or even (perhaps a bit cheekily) 3.99G.

Whatever you call it, by the time the 3G World Congress last November rolled around, a lot of delegates and speakers were talking about it. And not just in regards to W-CDMA. On the CDMA side of the cellular industry, CDMA vendors were talking up cdma2000's evolution beyond EV-DO Rev A, which gives the technology more symmetrical data uplinks and downlinks. Little of it was a mystery - the CDMA Development Group has said for years that EV-DO would essentially be followed by a multi-channel, all-IP version, which is now known as EV-DO Rev B (formerly EV-DV). Still, the CDMA camp had clearly shifted from simply talking about it to actively promoting and developing a specific technology roadmap.

That said, the LTE (for both W-CDMA and cdma2000) isn't so much an evolution to 4G itself but a roadmap to help the cellular industry get there and do its part in bringing 4G to life. That's because 4G - at least as the telecoms/IT industries now understand it - will be nothing like 3G. 3G was primarily vendor and regulator driven, with the two main industry coalitions developing their own standards under the ITU umbrella standard IMT-2000. 4G will be a far more complex animal, encompassing a variety of technologies, from wide-area cellular and wireless broadband networks to mobile TV and personal-area networks using UWB, Bluetooth and ZigBee, all IP-enabled for seamless mobility between them.

Consequently, the details are mind-bogglingly complex, and the roadmap itself is still riddled with gaps. Little wonder then that for all of the grumblings among some industry players and analysts that it's too soon to be talking about 4G, others are saying that its sheer complexity demands that all players in the telecoms value chain start working on it now.

The many faces of LTE

Indeed, even the LTE itself is still in some ways a work in progress, as vendors continue to promote their own ideas to the 3GPP.

For example, it's well understood that the next step after HSDPA and HSUPA (the uplink version of HSDPA that will give W-CDMA more symmetrical data throughput speeds in the multi-megabit range) will involve adding technologies like OFDM and MIMO to the mix.

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