The LTE PR juggernaut is running on all cylinders, with several LTE networks already in commercial service (albeit on a limited basis), and more expected to go online before the end of this year. In fact, the 3GPP says that 22 operators will have launched LTE by year-end which is an eye-catching number, considering that this time last year, only three major operators NTT DoCoMo, Verizon Wireless and TeliaSonera had definite plans to launch LTE services before the end of 2010.
There is still plenty of skepticism about the business case for rolling out LTE that early, if only because of the paucity of devices. Voice-centric LTE handsets are still two years away, according to Ovum's consulting director for Asia Pacific, CW Cheung, making LTE a data-only proposition for those launching now.
But the rollouts are happening now, and more and more trials are being announced. Perhaps more tellingly, the discussion around LTE is shifting away from technical capabilities and data speeds (which are currently within expectations, according to LSTI) towards the practical issues of deployment, and - more to the point - how much it's going to cost operators to roll it out.
The answer will vary from cellco to cellco, of course, but one clear trend is that LTE raises some serious challenges to the old way of deploying cellular networks - i.e. macro cells with wide-area coverage. Even discounting the fact that most LTE networks will be running initially in the 2.6-GHz band, which means shorter ranges by default, LTE cells will be smaller than ever, putting a premium on cell capacity over coverage. That's already having an impact on base station design (and for the better, by most accounts) but it also potentially means a lot of extra deployment costs for cellcos - unless they deploy LTE in strategic islands.
No more macros
The reason LTE requires smaller cells, says Dr Shahram G Niri, director of global LTE/SAE strategy and solutions for NEC Europe, is that the escalating growth of mobile data usage is emphasizing the need for maximizing capacity per cell, which in the 3G world means spectrum reuse.
"Even today, 3G cells are down to a few hundred meters or even a hundred meters in some cases, when it was supposed to be kilometers," he told Wireless Asia. "That's because we're learned that of all the techniques we've come up with to increase capacity and the spectral efficiency, the biggest gains we're had was from reusing the frequency, which means we can reuse the same frequency everywhere, but that means smaller cells."
The same applies to LTE, even with the wider spectrum bands being allocated for it, he adds. "With LTE, the spectrum we have will not be enough to accommodate the growth of data traffic that we're seeing."
Bjorn Amundsen, VP and director head of mobile network coverage for Telenor, says his company has reached the same conclusion in its home country of Norway.
"Even just for 2G and 3G, in the inner circle of Oslo we have a base station every 50 to 100 meters today," he says. "Looking ahead two or three years to LTE, you'll need a base station probably in every building or every second building. That's going to be a huge cost."
Site acquisition costs
With operators - particularly the ones that blew billions on 3G ten years ago - more cost-conscious than ever when it comes to network upgrades, equipment vendors have been redesigning base stations that are smaller and cheaper, as well as cheaper to run thanks to lower power consumption. But while that's a welcome development, says Amundsen, the gear is just one part of the cost of a given site.
"The biggest issue for us in rolling out LTE isn't the cost of the base station, which is the cheapest it's ever been and getting lower and lower. The real cost to us is installing the equipment into buildings," he says. "That's not getting lower that's increasing enormously. And in Norway at least, the cost of installing power to the base station is extremely expensive if you look outside the cities, up to $100,000 per km to get the power supply to the base station."
That's why Telenor's 3G coverage covers 80% of the population but only 23% of the land area, he notes.
Adding to the cost of LTE is the fact that for most operators, it't essentially another RAN overlay, says Niri of NEC.
"Actually many of these operators are running 2G and 3G already, and now we have 4G - it's difficult enough to run two networks, let alone three," Niri says. "Previously, the common belief was that 2G would be switched off somewhere around 2010 or 2012, but with the exception of Japan, we're now being proved wrong. 2G is going to be around for a long, long time. So any third network we introduce has to be simple to run and cheap to run."
Smaller form factors
Which is why vendors like NEC are advising a different approach to LTE forget macro cells and ubiquitous coverage, and focus on key congestion areas with RAN gear tailored to the purpose.
'We're telling customers to not to do macro anymore,' Niri says. They don't need to be everywhere - that's been proved with 3G -' and a macro network can provide the coverage they need but not the capacity. You need small cells, and that means you can't use the same platform as before - you need tailored equipment that's more compact, lightweight, easy to install and easy to manage."
Those kinds of requirements are driving a new approach to base station design that takes the headaches of site acquisition into account by essentially enabling them to be installed anywhere, says Joachim Hallwachs, marketing VP for DesignArt Networks.
"LTE will require ten times more cell locations than 3G, and that can't be done with the existing cost model," he says. "Is base stations get smaller, operators will be looking to acquire sites wherever they can get them, including rooftops, traffic lights and street lamps."
Consequently, Hallwachs says, operators need low-cost installation in a commercially viable site, which means it can't require lots of construction or come with high lease costs. We're seeing distributed base stations with remote radio heads and centralized baseband units, which lowers the footprint. But it's still actively cooled, and you need a shelter for it. What you really need is extremely compact gear with minimal power consumption, passive cooling, and no need for a shelter."
Hallwachs also distinguishes between femtocells - often touted as an offload solution to help cellcos manage spectrum capacity - and carrier-class base stations creating smaller cells. "The sites we're talking about will have to be software upgradeable, support remote management, and other things not associated with femtocells."
They'll also require technologies like SON (self organizing networks) with full automation, and wireless backhaul, says Hallwachs. "Wireless backhaul will be mandatory, but line-of-sight [LOS] wireless backhaul will no longer be feasible in this rollout scenario, so you need non-LOS technology."
Actually getting the base station essentials in pole-mounted form will require squeezing all base station functionality into a single box - something that DesignArt says it's enabling with its SoC (system on a chip) solution, which not only means a smaller form factor, but also one that can run on passive cooling.
"What used to be a roomful of computer equipment now fits in my hand,"he says, holding up a smartphone. "Why can't we do the same with a base station?"
Vendors are already moving in that direction, albeit from different directions. Smaller footprints and passive cooling, for example, has been addressed by vendors developing base stations for rural areas off the main power grid with the aim of making them easier to install without the need for air-conditioned shelters.
Vendors like Alcatel-Lucent are also working towards getting base stations small enough for ad hoc installation, says Philippe Poggianti, Alcatel-Lucent's VP of LTE.
'By 2012, maybe, you will see antenna panels the size of an A3 sheet of paper and around 15cm thick that can be mounted on lampposts,' Poggianti says.
Islands of LTE
However, there's still some debate over whether all this will make LTE more expensive to roll out than operators initially imagined 'particularly given LTE's initial promise of cost savings via better spectral efficiency and the flatter all-IP architecture behind the base stations. Whatever their size or the cost of installation, more sites could add up to bigger expenses, particularly once backhaul is figured into the equation (see "Thorough planning needed for 4G backhaul," as well as this issue's feature, "Rethinking the backhaul").
Enyen Cheong, APAC marketing manager for test and measurement at JDSU, argues that the economics of LTE still make more sense when looking at the total cost of ownership. "It's not just the RAN sites, but also the flat IP architecture, Ethernet backhaul and related opex savings."
Christian Daignault, chief technology officer of CSL - which has already deployed its LTE network on top of a revamped all-IP network - insists that the business case for LTE is its opex efficiency gains in the longer term.
"If you don't deploy LTE, eventually your network will cost a lot more to run as your traffic grows,"he says.
However, CSL is also picking and choosing where to deploy LTE - which is to say, in the hot-spot areas where traffic congestion is highest, with a fallback option of Dual Cell HSPA+ (see "CSL's 4G network is ready, awaiting devices" for details).
In other words, the secret to deploying LTE cost-effectively may be to forsake the old macro model and create selective islands of LTE.
That's how Telenor is doing it, says Bjorn Amundsen. "We are actually making a business case for every single base station we are building in the cities. It's the only way we can do it."
Amundsen offers an example of how it works: "If you're a customer and you come to me and say you need indoor coverage, and your business depends on it, I would say if you sign an agreement with Telenor for 12 months or two years, or whatever, we can build that indoor station. And if you're the owner of the building I will ask for you to let me stay free of charge. If you can do that, I can build it and we can start tomorrow. If you're not the owner, I must balance it and look at the income and the cost, and if I can make money I'll do it, but if I'll lose money, I won't."