City of London deploy Urban Small Cell Mesh Network

I visited the City of London, the 1 square mile central business district within the metropolis dominated by international finance and big business. The governing body recently awarded a concession that provides free public Wi-Fi in return for street level small cell sites. Services have been launched after only 28 weeks. I spoke with both City officials and the project manager to appreciate the benefits to all involved.

Strong leadership from the top

While some city authorities look at mobile operators as purely another potential revenue stream, others take a more balanced view. Steven Bage, Strategic Infrastructure Advisor in the City Surveyor’s Department, explained how the council wanted to ensure the City had wireless service fit for the future.

The level of service was perhaps most publicly embarrassing during the otherwise successful London Olympics of 2012. Cycling and running events through the city couldn’t be properly viewed worldwide because the TV networks tried to upload live video from their cameras via grossly overloaded 3G. Event GPS tracker updates were throttled by floods of tweets. Today, even with extensive 4G coverage from rooftops, not all network operators can claim ubiquitous service and network capacity remains a problem.

With full support from both current and past Leaders of the City Corporation (“this is one of their top three priorities”), different departments have all collaborated to streamline the practicalities. Top down leadership has really helped the project to thrive.

Small Cells and Wi-Fi in the vanguard of Smart City evolution

Commercially the City of London Corporation opened up a competitive dialogue tender, asking the market for several capabilities. They made a point of asking for solutions rather than defining how any supplier might achieve it. They initially asked about Smart Cities, then realised the concepts weren’t quite yet evolved enough, and focussed first on Small Cells and Wi-Fi in the knowledge that this would support long term Smart City thinking.

DAS solutions were considered during this process, but these would have involved a huge initial capital outlay and the remote radio units themselves were quite a lot more obtrusive from a planning perspective. There would have been a lot more time-consuming disruptive street works to connect fibre to each location, rather than using wireless. Small cells, connected by wireless backhaul, seemed to be a lot more attractive approach.

CTIL awarded 15 year concession

Earlier this year, a concession of 15 years was won by CTIL, the organisation responsible for both Telefonica O2 and Vodafone’s national UK network operations. CTIL must install and provide free-to-all Wi-Fi throughout the district, and can install small cells at almost any street location on request from any operator. The site rental/operational fees paid for each small cell should cover the cost of the free Wi-Fi and are expected to make a small surplus after year 7, some of which will flow back into the council coffers.

Unlike concessions in some other London boroughs, there’s no up-front payment by either party with all the initial investment funded by CTIL. Although the City of London isn’t looking to make vast profits out of the concession, they do have an obligation to get market value for these assets.

CTIL and Telefonica O2 built the network within 28 weeks in partnership with Virgin Media, UK Power Networks and the City’s Highways contractor, J B Riney & Co Ltd. iWireless undertook the systems integration including planning and optimising the Wi-Fi network.

Full access to almost any streetside location

The historic streets of the City of London date back more than 2000 years. It’s not a grid system and there are many winding alleyways dominated by towering skyscrapers, making seamless radio coverage difficult to achieve. Helpfully, the council has the power to approve any installations on public assets in the street for societal benefit. Surprisingly, that’s not the case for anything placed on the side of buildings which would need the building owner’s consent. While there is a specific Act of Parliament that permits installation of street lights on building walls, it doesn’t extend to other equipment.

Recent city planning initiatives to open up public spaces and reduce street clutter have led to street lighting poles being removed in favour of wall mounted ones. It’s easy to overlook that these busy areas are often where most cellular capacity is required. Fortunately, it’s quite feasible to physically install a street pole where required for a small cell, even if not required for lighting.

Agreeing de-minimus planning streamlined the process

Steven has worked closely with the planning department, especially the conservation area planner, and agreed “de minimus” physical constraints. These avoid the need for individual planning applications or approval for every individual site. Each street pole can accommodate up to two devices, which could either be both small cells or a mix of Wi-Fi and small cell, together with a wireless mesh backhaul transceiver. All must be painted black to blend in with the standard street pole colour scheme.

The corporation has been advised that Wi-Fi will remain relevant outdoors for at least the next 7 years. Steven told me that they previously had an existing public Wi-Fi service provided by The Cloud (now BSkyB) which they wanted to replace.

“CTIL and O2 came up with a fantastic design using the latest Cisco 802.11ac gigabit speed units. We’re very pleased with the results so far and will review whether to refresh the equipment in 7 years time. If there’s sufficient capability in the mobile networks, perhaps we may discontinue – it’s hard to tell what the situation will be that far in the future.”

“The Wi-Fi network covers the entire area, perhaps not every individual lane, but all of the busier areas with high footfall. It’s been installed in less than 28 weeks, quite unique for that amount of fibre deployment in the City. We minimised excavation, reused existing tunnels and ducts, worked out of hours/weekends.

Our surveyors did a great job, contributing extensive local knowledge alongside their highways authority colleagues. Their encyclopaedic knowledge of what’s buried under the streets made the planning very expeditious.”

The photo below shows a mesh relay point (on the black pole to the left of the Gresham Street sign) serving both the alleyway and hosting a Wi-Fi access point. There were line of sight wireless links down the alleyway and on both left and right on the main street. The height of the wireless backhaul helps avoid obstructions from traffic and increase the range of the small cells.

Combining fibre and wireless mesh backhaul

CTIL technical program manager Jamie Olejnik, who is ultimately responsible for the Wireless Concession, indicated that their target cost is for 10% of a typical macrocell deployment. A managed service combining shared wireless backhaul mesh, fibre transmission, pre-approved planning procedures and efficient installation procedures make this very cost effective.

32x 1Gbps fibre backhaul links were installed, connected to a series of distribution points. CCS wireless mesh backhaul has been used at street level with a fan-out of approximately four sites per fibre connection. The mesh solution ensures that alternative routes can be taken for redundancy or load balancing. Unlike some other more modern cities, it just wouldn’t have been feasible to dig up the streets and install fibre to every node due to cost, disruption and timescale.

The photo below shows the CCS MetNet unit in its normal colours, easier to see than when disguised in black. Further down, you’ll see how easily this blends into the cityscape.

Unobtrusively blended into the background

When I asked Jamie what his biggest headache had been, perhaps surprisingly he said that painting the equipment regulation black was high up on the list. It seems that ensuring all the legally required labels remain visible takes a lot of extra care.

This approach works well. Despite being black and all air-cooled, there are no overheating problems.

The choice of site location is critical – just 50-100 metres away from the highest footfall might reduce the payback. The advantage of using poles gives longer range and less disruption than lower down, avoiding blocking by vehicles. Most go completely unnoticed. For example, what do you notice first on the pole below - the parking restriction sign or the small cell?

Below you can see Wi-Fi, Small Cell and wireless backhaul on the same pole in a busy street across from St Paul’s Cathedral, visible only from this angle and otherwise discretely blending into the background.

Small Cell planning

Telefonica’s urban small cells are provided by Nokia, although other vendor’s similarly sized equipment could be used. A comprehensive survey of existing street poles, including their weight bearing suitability, has provided a large number of existing sites for cellular planners to choose from. Others can be added on request.

RF planners tell me that using low power down in street canyons can be very efficient. While some RF planners would prefer to serve everyone from macrocells from the rooftops, lighting up ever more spectrum, I’d suggest that street canyons found in the City of London benefit greatly from street level transmitters and the wide choice of location. The slow moving traffic and large number of pedestrians further emphasise the validity of this approach.

Each Nokia Flexizone small cell can handle 100 or more active users, typically within a range of 100-200 metres, using an RF power of 5W maximum. Spectrum reuse is high, which would be a key advantage for operators with limited amounts of it.

Rapid take-up of services

Already there are over 64,000 users per day accessing the Wi-Fi with a further 100 new registration daily. It’s a free-to-use service with a one-time registration and no spam marketing email.

There will be over 50 small cells live by the end of 2017 and plans for 260 by end 2018. The system is open for use by all operators, with the first already installed for Telefonica O2 and another keen to proceed. All are LTE-only today, and that’s likely to remain the case. Sites are available on a “first-come, first-served basis”.

End user experience

I walked around the area and tested the Wi-Fi service myself. Performance in the more remote hidden alleyways was extremely impressive. While I didn’t have a Telefonica SIM to perform similar tests on the small cells, I see no reason why that wouldn’t achieve at least as good throughput.

Celebrating Success

I have to say it’s great to see such a system in commercial use today – we’ve seen much talk about the potential opportunities for Urban Small Cells, and now here’s one practical success. 28 weeks from start to commercial launch is a timescale to be proud of.

At the end of the day, it will all improve the quality of life for those working and living in the City of London, ultimately benefiting business and social development.

By the way, this new Small Cell network isn’t the only time we’ve got something first in the streets of London…