The small cells market is developing apace with new vendors entering the market and plenty of innovation across the board. But when it comes to major small cell rollouts it always seems to be jam tomorrow for the vendors if industry opinion from the recent Small Cells World Summit in London (10-12 June) is anything to go by.
Elias Aravantinos, lead analyst at ExelixisNet, which has recently published a report: Small Cell Ecosystem: Challenges and Opportunities, says: ‘The big problem is that two years ago the forecasts were over-estimating the small cell market, and it hasn’t happened. The big mobile operators still want to get the most out of their macro networks and are resisting the use of small radios outdoors.’
Professor Andy Sutton, principal network architect at the UK’s largest mobile operator EE, does not disagree. ‘EE’s focus is on rolling out our 4G macro network at the moment to extend coverage as much as possible. But we are also looking at what comes next; we are really talking about HetNets and how that is managed.’
EE, like many mobile operators is undertaking trials for both access and backhaul of small cells, but it is the indoor small cells sector that is gaining the most traction.
‘The bulk of growth globally in small cells is focusing on coverage and specifically indoor coverage. Typically, they are looking at distributed antenna systems (DAS), RF distributor systems and now enterprise picocells,’ observes Shayan Sanyal, chief marketing officer at small cell access and backhaul provider Bluwan.
Operators are attracted to indoor coverage solutions because there is an obvious business case in targeting the enterprise sector, if they can find the right revenue model and go-to-market approach. Indoor coverage solutions also appeal because they are easier to deploy than outdoor cells (fewer third parties to deal with) and they can sell additional value added services such as cloud and tele-presence services.
Indoor small cells
For the moment then, it’s the indoor market that shows the most promise for small cell rollouts. Reflecting that trend, Nick Johnson, CTO at indoor small cell specialist ip.access, comments: ‘Small cell sales are definitely on the up after a difficult couple of years for the industry, which was flat in terms of growth. We are looking forward to steady growth, but we expect some explosive growth in the second half of the year.’
Challenges for small cells in the indoor space include, scalability, inter-cell interference management, seamless cell handover, backhaul and not interfering with the operators’ macro networks.
For SpiderCloud Wireless, which recently signed deals with Vodafone UK and Netherlands to supply its small cell solution, the key aspect of providing indoor coverage and capacity is the ability to be both flexible in deployment and above all scalable.
‘For a large enterprise where you may deploy a massive amount of radio nodes you need a controller behind the access points to manage that,’ says chief marketing officer Ronny Haraldsvik, who argues that without the presence of a local control point on a customer’s Ethernet network, a mobile operator cannot effectively coordinate small cells or support inter-small cell signaling.
‘Yes, you can put an LTE controller in the cloud,’ he notes, ‘but you will have interference at the edge with 3G/4G handover. The best way to fix that is to put the controller near the problem, not back in the cloud.’
Others beg differ. Airvana unveiled its ‘plug and play’ OneCell LTE small cell, which is based on Cloud RAN principles, at the Summit. OneCell consists of a baseband controller and multiple radio points, which form a single ‘super’ cell, which Airvana claims eliminates handovers and inter-cell interference issues. It also supports multiple operators.
Outdoor small cells
Few people doubt that operators will deploy outdoor small cells at some point, but exactly when is harder to fathom. Aravantinos says: ‘My opinion is that the operators definitely know there is a need for small cells, but it is still a wish. They wish to have them, but they are waiting for the momentum to pick up. Customer pressure will force them to move, but 4G subscriber levels are not high enough at the moment to make that happen yet.’
The outdoor small cell business model isn’t stacking up at the moment, but while customer pressure may be an eventual driver, Aravantinos believes apps may provide a revenue stream if operators can provide a service customers are willing to pay for.
Urban small cell deployments come with plenty of challenges as Aaron Partouche, director of corporate strategy & business development at Colt Technology Services, outlined at the Summit.
Among the key issues identified by Partouche are: building out backhaul networks that are both resilient and flexible enough to increase capacity when required; obtaining council/owner rights to site infrastructure; interference mitigation; operator certifications; and an unproven return on investment.
Partouche argued for better collaboration between all parties for small cell outdoor installation and integration to create an efficient maintenance and operating model and help camouflage equipment among street furniture.
He also encouraged the idea of sharing infrastructure between MNOs and called for the industry to look beyond just mobile and to investigate the needs of smart cities. Smart city applications could be a key revenue driver for small cells and just as importantly may help to reduce costs through sharing deals thereby avoiding duplication.
Finding a cost effective go-to-market solution is going to be absolutely vital. EE’s Andy Sutton says: ‘Small cells have to be cost effective, around 10% of the cost of macro cells, but it is so complicated to do. We need a more sensible approach, but it is a very fragmented ecosystem out there with councils, Arqiva, Virgin and others all owning bits in the UK. We need that ecosystem to mature a bit.’
Bluwan’s Sanyal argues that the industry needs to engage more with city councils or the likes of Transport for London (TfL), which has a lot of street infrastructure suitable for mounting small cells. ‘Operators need to engage with street furniture owners. We need to think differently to the traditional straight leasing model.’
EE’s Andy Sutton agrees: ‘We need to identify the win-win scenarios, as to how we work best with organisations like TfL and councils. The sheer number of sites we will need to deploy is huge, so small cells will be pervasive, but they need to be invisible.’
Backhaul for small cells
If there is one thing everyone agrees on it is that backhaul is a critical issue for outdoor small cells. It is an area that has seen a burst of innovation with solutions appearing in a bewildering variety of spectrum bands.
Andy Sutton favours the ‘toolkit’ approach. ‘I am convinced that small cell backhaul will require a mix of different strategies. We’ll use fixed products like fibre, our existing macro backhaul and we will also look at wireless alternatives.
‘We are exploring point-to-point (PTP), (point to multi-point) PTMP, MPTMP (multi-point to multi-point) and meshing to provide connectivity and to enhance reliability. We are primarily interested in line of sight (LOS) solutions at the moment. Non-line of sight (NLOS) does show some tactical opportunities though.’
Sutton continues: ‘We think V-Band at 60GHz is very appropriate to small cells; it is generally unlicensed, but the probability of interference looks very low and our trials support that belief. But I worry about the use of the 5GHz unlicensed band if the noise is increasing, as more uses are found for it. I don’t think LTEu is a backhaul band for the long term, although it may have some short term uses.’
LTEu is an initiative launched by Qualcomm to use LTE-Advanced in the 5GHz unlicensed band, sharing it with Wi-Fi. Sutton adds that the problem with sub-6GHz backhaul solutions is the lack of spectrum and the impact that can have on latency among other problems. ‘But EE is exploring certain applications for sub-6GHz, but more for rural areas where certain bands aren’t used for radio access.’
He says: ‘E-Band at 70-80GHz is a bit more expensive at the moment, more on a par with macro radios, but there are some disruptive providers coming into that space. We might use it in a dense macro environment or for a first hop from the macro to the small cell layer, possibly combining it with V-Band.’
He adds that one of the attractions of E-Band is that despite being higher spectrum, it can achieve a longer range than V-Band, because the spectrum can keep being reused.
His views confirm Sanyal’s observations on the current state of the small cell backhaul market. ‘There is a lot of traction in V-Band and sub-6GHz backhaul, but there will be a time when this is not the prevailing solution,’ he argues.
‘For the moment, there is not a huge amount of market share for other vendors using the other bands,’ he says. ‘But we think we will achieve success, because of the higher capacity and security you can get with our LinkFusion product in the Q-Band (40.5-43.5GHz), which we see as a fibre extending solution.’
Picking up on operator preference for LOS solutions, ExelixisNet’s Aravantinos says: ‘NLOS small cell vendors claim it is easy, but some say it isn’t working well yet. There are a lot of trials going on, but there are synchronisation and capacity issues, so perhaps NLOS solutions are not quite ready yet.’
On that subject, Tarana Wireless’s VP of marketing, Steven Glapa, acknowledged to delegates at the Summit that operators are not seeing the answers they want from NLOS backhaul solutions yet. NLOS products are affected by NLOS multipath, co-channel interference (where a high number of radio nodes makes it difficult to spectrum stack), unlicensed Wi-Fi interference and dynamic obstructions such as vehicles, trees and changing weather conditions.
‘All of these things can wipe out your NLOS solutions, as tests seem to show at the moment,’ Glapa said. However, he pointed to Tarana’s demonstrations of its NLOS AbsoluteAir solution and claimed that it has found ways to overcome all these problems. Despite this it seems there is a little way to go before the MNOs are convinced on NLOS solutions.
As regards the use of the 5GHz unlicensed band, Lance Hiley, director, European business development at Fastback Networks, which has developed at 5GHz backhaul solution, outlined a trial undertaken in Leeds with Virgin Media Business in the UK.
Four vendors, Sub 10, Intracom, Siklu and Fastback, were asked to trial their solutions using a Virgin Media fibre POP and meet minimum latency and throughput SLAs in a dynamic environment (including 80mph winds).
All four vendors met the SLAs. However, Hiley’s point was that Fastback could provide near LOS, LOS and NLOS in one PTP (a PTMP version is in the works) solution. While there were naturally variant results between the three, Fastback was able to demonstrate successful backhaul in all three that met Virgin’s SLAs.
Looking ahead, it seems that most small cell vendors will have to keep their belts tightened for at least another 18 months before any major rollouts start. But while some backhaul solutions seem more favoured at the moment, there appears to be a good chance all the options out there will eventually get used as 4G networks mature.
Summing up, EE’s Andy Sutton says: ‘In the perfect world you’d want PTP dark fibre to everything, but we don’t live in that world. So, what we want is high performing solutions to the right location at the right price point – that will require a toolbox approach mixing fixed and wireless solutions.’