Femtocells, not 4G, will solve spectrum crisis
Ofcom bets big on small cells
4G will improve capacity by only 1.2 times, according to the latest research, so better network topologies will be needed if we're going to get the bandwidth it seems we'll need.
Solving the widely anticipated data crunch will require better-designed networks, rather than new generations of radio standard, according to the latest research (PDF, surprisingly dull) carried out by Real Wireless on behalf of the UK regulator Ofcom.
The independent consultancy reckons that 4G (LTE) deployments will only improve spectral efficiency by about 20 per cent, despite offering much-improved speeds to individual users. So the best way to increase the overall capacity of the mobile networks is to build a lot more base stations rather than depend on magical new technologies to do more with less.
That conclusion isn't very surprising: the later versions of 3G (including HSPA and those other variants that Americans already call "4G") are very spectrally efficient. The limit on 3G is really a physical restriction on how much data one can squeeze into the 5MHz channel defined by the 3G standard.
Some extensions to that standard are already lashing together 5MHz channels for greater speed, but 4G (LTE) is much better at dynamically allocating a channel from 1MHz up to 20MHz in width depending on the application being used. That enables LTE to achieve headline-grabbing speeds for individual users, without being significantly faster than 3G.
The best way to carry more data, therefore, is to transmit it less far, so that frequencies can be reused more readily. If my nearest base station is 10 miles away, then the signal from that transmitter is sent into an area 50 square miles in size, while the one coming from my phone fills a circle of 314 square miles. Put the base station a mile away and those figures drop to a shade over a tenth of a square mile for the base station, and .8 from the handset.
Those figures are our own back-of-an-envelope stuff, but it is obvious that packing base stations closer together means frequencies can be reused more often, and thus the capacity of the network increases proportionally. LTE has many features to facilitate exactly that; OFDM reduces interference from neighbouring cells and LTE enables a very fast soft hand-off between cells, reducing the signalling load on the network.
So we will need 4G to make the future happen. Not because it can carry more data than its predecessors, but because it enables a greater density of base stations to be deployed. Good news for base station manufacturers, but bad news for those who want to know where all those base stations are going to go. ®
@Anton Ivanov -- The real issue is limited spectrum (and spectrum management).
Once upon a time when the ITU was an orderly place--a time before many countries caught the disease of downsizing, outsourcing and or amalgamating their spectrum management authorities along with their spectrum management engineers--and a time when radio and electromagnetic propagation characteristics were actually taught as core subjects to all electrical/electronic engineers--there would have been no debate like this one, as the cognoscenti would have implicitly understood that the laws of physics impose strict rules and limitations on the mount of available bandwidth in every form of radio propagation. Again, one has to remind protagonists that the term 'bandwidth' was actually coined by radio engineers and not those in computer science.
Yes, there would have been a general widespread debate amongst engineers about the best methods of delivering the required channel bandwidth to a specific service area. It would have involved such topics as how to optimise/maximize channel availability but minimize interference between all users of a limited radio spectrum. Adopting such methods as effective protection ratios (correct distance, power etc.) between separated users [read 'cells'] using the same channels/frequencies. Also, there'd have been a rational logical debate about which services [users] should be allocated wireless (along with channels, modulation types etc.) versus services that should only be transmitted by fibre.
And if there'd been a non-lunatic green movement back then, it'd have concerned itself with seeing that fair access to the radio spectrum was had by all users whilst still being very cognizant of the fact that every additional user who uses radio spectrum generates a small but significant non-linear (inseparable) radio noise which, collectively, is polluting the electromagnetic spectrum across the whole planet. Effectively, the once-quiet radio spectrum's noise floor is being continually raised to the point where some important essential services and military circuits are beginning to notice a degradation in the quality and performance of their communications. Even passive [non-transmitting/radiating] radio astronomers are suffering significant intermodulated noise interference from millions of radio users.
Ah but alas, much electrical engineering and all digital and computer engineering and programming courses don't teach a damn iota about this stuff or the need for proper control (prudent regulation) over the radio spectrum. Right, the very users--especially those who are demanding access to more spectrum--aren't taught a damn thing about its management. The consequences are that we've a trite and ill-informed debate about the critical radio spectrum infrastructure and that even includes many poorly-advised government policy makers.
Also, the fact that only limited improvements in bandwidth utilisation can be obtained from using G4 (as per this El Reg article) hasn’t come from a plethora of other sources and that it's late in the day, only backs up my assertion there's a wide lack of knowledge about spectrum management, both generally and in IT; and that now there are too few experts working in the area as consequence of reckless government policies.
It's a debate where the blind leads the ignorant and vice versa. Even the IEEE--whose long history put it into the thick of the spectrum debates of the first half of the 20th Century--has gone to ground and is showing little leadership in the wireless internet debate.
How debased and messy this debate has become can be seen by the IEEE's failure to criticise the totally unacceptable technology of Broadband over Powerlines, BPL, (PLC, Powerline Communications). It's a technology that attempts to transmit the internet over the world's power grid without acknowledging the fact that the millions of miles of power cables also act as good antennae; thus, if BPL were to be widely deployed, then it would be the largest polluting source of the radio spectrum ever devised. The IEEE even published an article on BPL in its Spectrum Magazine expounding the virtues of this nasty technology (even the word 'technology' is seemingly so inappropriate here).
And where were the Greenies when really needed. Can't see 'em for dust. Right, this bunch of useless 'spiritualist' would rather hug whales or trees than be involved in something that's both important and requires some actual technical nous.
The fact is that the radio spectrum is a fixed given, it's not infinitely extensible and only comparatively small parts of it have properties that are suitable for the general transmitting of internet data, and we're fast filling those up. Advocates of wireless internet technology are correct when they say we can squeeze more channels out of the spectrum by using better techniques such as improved modulation but the law of diminishing returns is beginning to set in--illustrated by the need for 'femto' cells etc. There's no doubt that such developments will have to go hand in hand with the widespread deployment of very fast fibre.
rural ... high speed broadband
"If a rural community wants high speed broadband why not have them get a microcell installed on the local church or community centre. They could then all take advantage of 4-10Mbit/sec mobile broadband."
Er, Bob, care to explain how the data then affordably gets back from the church to the Internerd (and vice versa)? It probably doesn't, in the absence of "affordable high speed rural broadband". Chicken, meet egg. But if there was already affordable high speed rural broadband, the church wouldn't need the aerial.
Anyway, UK plc already has a national licenced supplier for fixed wireless broadband, why do we need another one (apart from the fact that Ofcon have let Netvigator (etc) sit on their licence and completely fail to deliver anything meaningful).
..because it's true :)
One other thing that's funny:If an area is dependant on xG because the broadband is crap - how do you get data from the femtocell back to civilisation?
Half a dozen femtocells is not going to help much if they all have 0.5Mb/s connections back to the nearest exchange.