Following up on my post from two weeks ago about HSPA / HSPA+ in 2.6GHz, I'm now more sure that this is a becoming a wise option - and operators and device vendors should start pushing their suppliers to support it. I'm becoming increasingly sceptical about the short-term case for LTE, especially for GSM/UMTS operators in developed markets like Western Europe.
The received wisdom suggests that "new spectrum = new technology". I can certainly see the appeal and elegance for radio network engineers to put the newest, shiniest kit into the spanking-new bits of frequency in 2.6GHz and the digital dividend.
But I think that for current HSPA operators, they should think twice. Even the theoretical gains in efficiency for LTE vs. Release 8 or Release 9 HSPA+ are relatively modest. With 64QAM and 2x2 MIMO, I've heard figures of 20-30% *might* be achievable. However, given views of contrarians like Moray Rumney from Agilent, these gains may well not be attainable in the real world - or at least, only for a certain proportion of the time under specific user/cell scenarios. In terms of actual *average* throughput in normal usage, there may well be only a wafer-thin margin between them.
Yes, LTE has better latency (in theory), a flatter and maybe cheaper network, and the ability to use thin slivers of spectrum.
But this needs to be set against the need to run LTE as an overlay on HSPA anyway (3 sets of network opex....), plus the extra cost and complexity in handsets, the huge testing and optimisation costs, the probable flaky hand-offs between LTE and 3G/2G, the ongoing issue of voice support and numerous other unknowns. Add to this the fact that LTE does not appear to offer any obvious new business models compared with HSPA+ (especially if only used in limited "hotspots") and the business case dissipates even further.
That's not to say LTE won't be improved - after all, HSDPA has proven a superb "bug fix" for WCDMA, only 5 years after it was introduced. Prior to that point, 3G was pretty pointless - in hindsight, operators would have been better off leaving the 2.1GHz spectrum unused, or perhaps temporarily putting EDGE in it, although under old regulatory regimes that probably wouldn't have been allowed.
This time, there are more options.
I think that operators should give serious consideration to the scenario of continued upgrades to HSPA, including putting it in new spectrum bands like 2.6GHz. Much of the new radio equipment could be easily upgraded to LTE at a later date - if required. There's possibly an argument to skip current LTE entirely and wait for real 4G - LTE Advanced - as an eventual migration path.
Given that operators are currently starting to put HSPA in refarmed 900MHz (surely also a "new band" effectively?), why not also 2.6GHz?
Either way - I think that operators should start leaning on their suppliers, both infrastructure- and device-side - to support HSPA2600 as an option at least.
Edit: any game-theorists reading this might also want to ponder on the competitive impact of those most benefiting from early scale economies for LTE devices (on any band). In particular, CDMA operators moving to LTE will likely be disproportionately affected if their HSPA peers don't follow suit at about same time. Will LTE enable a marketing win vs. HSPA+? Given that neither is 4G I can't really see why - 3.75G vs. 3.9G isn't really a great headline-maker. In fact, if WiMAX and LTE operators can use 4G as a branding device, I see no reason why HSPA+ operators shouldn't too.
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