Size matters: the value of small cells

It’s a truth universally acknowledged that the current data boom is only the beginning of a far greater explosion. But while the industry is looking to LTE to address this issue, Japanese vendor NEC argues that the new technology, too, is just the first step to coping with the looming capacity crisis.

For Dr Shahram G Niri, director of global LTE/SAE strategy & solution at NEC Europe and visiting professor at the University of Surrey, one key element of the solution will be small cells—compact, low power base stations that can be deployed more easily, more quickly and more cost efficiently in data hotspots than their large-scale counterparts. “At NEC we believe that small cells are a whole new way of building future mobile broadband networks,” Niri says. “They add massive capacity, in a very fast time, with a TCO which is absolutely a key to sustainability of mobile broadband business.” In fact, he believes that they will prove to be nothing less than essential as operators bid to stay ahead of growth.

“The challenge is that we have more users, more smartphones, more connected devices and more data hungry and video-centric applications. There’s no doubt that traffic is increasing and it is increasing exponentially. It is going to be a continuous challenge to stay ahead of traffic increases.” The most straightforward solution would be additional spectrum, but acquiring and deploying that spectrum is a major challenge for operators. Niri believes, though, that even if this were not the case, spectrum alone would not be sufficient to deal with the capacity issue.

“Spectrum is a resource that’s finite, and very expensive, and very hard to harmonise across regions,” he says. “Let’s say, for the sake of argument, that you double the amount of spectrum available for mobile broadband between now and five or 10 years’ time. You double the capacity, [but] you are looking at scenarios where traffic increases somewhere between a minimum of a hundred to a few hundred times. How are we going to cope with that? The spectrum shortage is a real problem and industry needs to look more seriously into this.”

Technology advances such as higher order modulation; coding, clever scheduling and MIMO won’t be enough to deal with this capacity crunch, Niri says and the barrier is the laws of physics. “We are reaching the upper limits of spectral efficiency in terms of the amount of bits we could really squeeze from every MHz of spectrum.”

Adding more macro cells is not the answer either, he says. “The current macro networks are complex, costly to operate and still will not deliver the desired performance. New network topologies and deployment methods will offer more gains than new technologies and hardware. Frequency reuse is the key to keeping up with the exponential increase of traffic in the future.”

The answer to the problem, he says, is small cells, and the efficient way they use the networks. NEC says its tests have shown that small cells can deliver around three times the throughput of a typical network of macro cells. Small cells with low power radios are designed to support a limited number of subscribers – usually in the tens and hundreds rather than thousands of macro base stations, but conversely they are also faster, simpler, more efficient and more cost-effective.

“Small cells are moving right to the heart of the network,” Niri says. “And they are a good solution because they help to drive the cost down. At the same time they improve the user experience, add value and help to increase revenue.”

Naturally, other vendors have also seen the potential of small cells, so what is it that NEC believes gives it an advantage in the market?

A combination of innovative and solid products and real world calls deployment experience, says Niri. “At NEC we are pioneers in small cell solutions. We’ve been at the forefront of this paradigm shift.”

Niri cites the firm’s operator engagements, particularly in its home market of Japan. “I think this goes back to our experience in mobile broadband. We’ve were behind the first 3G network in the world in Japan in 2001 – the leading broadband market. We were behind the first 3G network in Europe in 2003. We’ve also had a lot of success in pioneering 3G femtos [combined] with a deep understanding of mobile broadband.”

Then there’s NEC’s small cell technology itself, he says. “What we’ve done in small cell technology is to make a really compact and really high performance and intelligent product. And we’ve done it earlier than anybody else – I believe that we are a good year if not more ahead of the others.”

The challenge, Niri believes, is simply getting the small cell message across to the market and explaining that what worked for 3G won’t necessarily work in a data-centric 4G world; for LTE, operators will need to take a different tack.

“The tradition is to use macro for deployment— this has been the operators‘ bread and butter. In 3G, this made sense, as coverage was the driver—but then capacity became an issue when mobile broadband picked up. Yes, even today small cell technology is used in 3G, but what we’ve said to our customers is that the network dynamics are totally different. Coverage is not an issue—capacity, cost and performance are issues ,and they cannot be addressed with macro cells.

“Small cells are not a coverage solution—they are primarily a good way of providing a lot of capacity and superior performance at a lower TCO. [So] what we’re saying to customers is that it is the other way round to 3G. Build the capacity layer using small cells and then use macro to do out-fill to improve the coverage. This is a change in mind set.”

So do operators generally need educating over the benefits that small cells can bring? Niri believes they do.“We had to do a lot of hard work, all the way from theoretical simulations to business cases and TCO analysis to try and convince that this was a true solution. But through these joint analyses we have formed a very good understanding [with operators].”

Finally, Niri says that the received wisdom that the flat IP architecture of LTE simplifies the network maintenance is false.

“I simply challenge those who say that future networks will be simpler because you have a flat IP infrastructure. In fact, we are going to have more complex networks [offering] extreme mobility, ubiquity and personalisation. [They will be] video dominated and [deliver] surprising applications as yet unimagined. How could this network be simpler?”

The challenge Niri says is to design a network that masks the complexity as much as possible, yet offers intelligence, availability, resilience and speed—and all at a lower cost. It’s a tall order but one that Niri believes is necessary—and small cells will play a crucial role.

“We will surely see one touch and zero touch [plug and play] zero footprint small cells equipped with very intelligent SON in a variety of micro, pico and femto forms play a very big, if not the main, role in the evolution of mobile broadband,”he says.

The world’s first Small Cells event takes place in Berlin, Germany on 11-12th  October 2011

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