February 23, 2017
Wireless carriers face technical challenges in making connections between the network core and small cells. Randall Schwartz, a senior analyst and consultant with Wireless 20/20, led a session about small cell connectivity at the Tower & Small Cell Summit in September 2016. He said the limited number of users for a given small cell could help boost throughput.
A panelist in the session, Mike Alt, is vice president of network design at ExteNet Systems, an independent provider of distributed wireless communications networks. The company builds, owns and operates indoor and outdoor networks, small cells, and distributed antenna system (DAS) networks — any kind of interconnected distributed network system, as Alt put it. “We don’t just refer to it as DAS anymore, because it’s not just one topology,” he said.
Alt said that ExteNet Systems has been deploying small cells in some way, shape or form for 11 years. As a result of a rapid increase in wireless carrier demand for small cell deployments, carriers are seeking the most cost-effective way of building small cells, along with preparing municipalities for rapid, imminent network densification.
Small cell throughput translates into the signal-to-noise and distortion (SINAD) ratio, Alt explained. “When we’re integrating a network, usually on behalf of a carrier, the network operator doesn’t usually specify a speed, such as 600 kilobits per second, or something like that,” Alt said. “They’re basically saying they have to have 12 dB of SINAD variation between systems. If there is one significant integration challenge from the technical perspective, it is creating the isolation between the macro network and the small cells.”
Heterogeneous networks are supposed to work together, but Alt said that, in reality, they’re supposed to serve their customers, and only their customers, and then hand off to each other. Integrators spend a significant amount of effort to isolate the small cell coverage footprint and its capacity from the macro network, both for indoor and outdoor systems. Integrators are engineering indoor venues with signal levels to overcome signals that enter from outside.
Companies deploying small cells often take steps to make small cell installations aesthetically pleasing so, for example, a street doesn’t present a view with a lot of cell equipment. Alt said some situations are more challenging than others, such as making a wood pole still look like a wood pole when fitted with cell equipment.
“With wood poles, many installers use shrouds around the equipment,” Alt said. “Municipalities require some of it, and many have restrictions on how many attachments you can place on a pole. A single shroud that conceals 16 or 18 pieces of equipment behind it may be deemed one attachment.”
Smart poles, which are light poles with small cell equipment installed inside them, offer concealment, and they blend in with other light poles. The smart pole has functionality combined with aesthetic appeal. It may have Wi-Fi connectivity for a smart city application. The cell antenna could be concealed by a shroud at the top, and a uniform structure within the pole could contain a microwave backhaul solution.
“Another form of smart pole has LCD information displays, the ‘you are here’ kind of interactive map,” Alt said. “Cities are starting not only to see the aesthetics, but also applications for themselves. That’s where a smart pole provides a significant benefit. If you can go in a municipality and not only show the installation is not disruptive, it actually offers you something the city can use for its own benefit. That’s usually the win-win situation you try for.”
Alt said that when it comes to wireless networks, neutrality has a different meaning than it did three or four years ago. “With previous DAS deployments, neutrality was based on a fine demarcation between the carrier-owned equipment and the neutral-host DAS owner’s equipment,” he said. “Today, neutrality has numerous complex demarcations. The carrier will take its equipment to a point where then it joins with the host’s fiber, and then it goes back to their equipment, and then goes up to the host’s antenna.”
With blurred demarcation and neutrality, a small cell deployment may have a baseband unit and remote radio head combination owned by the carrier, and yet the infrastructure is owned by the neutral host. Alt said this changes the business, technical and operational structures need to be supported. “It is different than what it was when it was just a DAS deployment situation,” he said. “As a result, for both indoor and outdoor systems, when you start talking about a neutral-host scenario, the neutrality involves the attachment and the use of the fiber in many instances for any kind of small cell deployment.”
With indoor systems, the neutral host could think about supplying any combination of the antenna, the connection with the radio, the baseband, the power and the backhaul. Alt said that typically the host would own the antenna, the coax and the fiber. The venue or the host might own the small cell. The host has two customers: the carrier that is interested in serving subscribers in the building and the building owner itself. The venue may or may not have a financial interest in the system, but Alt said the venue certainly has an interest in the aesthetics of the system.
“The venue wants the antennas to be hidden,” Alt said. “The carrier wants ubiquitous capacity delivery. Suddenly, you are catering to two different masters. One wants ubiquitous coverage. The other says, ‘I don’t want to see any equipment. I don’t care what sacrifice you have to make on that.’”
When a venue has more than one wireless system operator, a given area might have to have more than one antenna. “Small cell deployments are becoming much more popular within venues, and the venues have to be resigned to the fact that they may see multiple sets of equipment,” Alt said.
It’s possible to view wireless service as a utility today more so than it was years ago, Alt said, when it was viewed as a luxury. He compared it with Wi-Fi service that most hotels used to charge for, and sometimes the Wi-Fi connection wasn’t even very good. Today, many travelers won’t use hotels that don’t provide good Wi-Fi service, and they expect it to be provided without an extra charge. Alt said many venues are taking responsibility for providing wireless service to remain competitive.
Nevertheless, Alt said there is a piece of the installation for which venues often expect the system operator to pay, and that’s the space for the equipment. “If the venues are allocating some space for the equipment, it’s very challenging for a venue to give that up for free because its goal is to rent space for money.”
Mike Alt, vice president of network design at ExteNet Systems. Photo by Don Bishop