We’ve heard of some installers/system integrators combining small cells with simpler DAS systems to achieve full multi-operator service. I spoke with Sina Khanifar of RSRF, a US company that’s been doing exactly that. He shared some insights and real-world experience that you might not get from operators or product vendors.
What’s the scope of your business?
We equip enterprise buildings with in-building cellular service, mostly installing solutions that supports multiple network operators. With headquarters in Laguna Hills just south of Los Angeles, we also have offices in Atlanta and San Francisco. We have customers throughout the continental United States including some well known brand names (Boeing, GM, Starbucks).
We design custom in-building wireless solutions for businesses in a variety of market segments, from industrial to hospitality. Each solution is tailored to customer requirements, and can use DAS (active or passive) or small cells.
Until recently, we’ve most commonly been using off-air DAS solutions because these are fairly cost effective. They receive the signal from an external rooftop antenna and rebroadcast the signal inside. We come across the usual issues, particularly with LTE of low SINR (Signal to Noise Ratio) and RFRQ (Signal Quality) which result in degraded overall service quality.
How have you used Small Cells?
We have often installed standalone Enterprise Small Cells where support for only one network operator is required. It’s the simplest, quickest and cheapest solution.
About a year ago we started using the Verizon LTE femtocell to drive passive DAS. When I say passive, I mean the system doesn’t demodulate the signal down to its baseband component although there is a broadband amplifier and some filters involved.
We're calling our approach for deployment "Small Cell Passive DAS" or "SCP-DAS."
This configuration can drive down installation costs to around 50-70 cents per square foot. This is really competitive price point from what used to be more like $2 using traditional DAS powered by regular basestations. Our biggest issue is getting hold of appropriate small cells from all of the operators.
How do Small Cell solutions compare between the leading US operators?
We’ve found Verizon’s Samsung Enterprise LTE Network Extender femtocell to be fantastic. The Verizon team have done a good job of making it easy to deploy, and it’s very much plug-and-play. These can be bought online or via a representative (provided you have a Verizon corporate account).
We’ve installed quite a few of these systems now and find they are working quite well. The architecture suits buildings that have a fair amount of floorspace but relatively few active users. Take a large residential tower block which might be up to 500,000 square feet. We might divide this up into four sectors, with one femtocells driving 10 remote RF heads in parallel spread across 13 floors of the building.
We’ve also tried this with the Alcatel-Lucent (now Nokia) enterprise femtocells. Their latest 9962 model used by AT&T supports up to 32 3G and 32 LTE users. They limit three femtocells per group and can’t seamlessly handoff internally if there are more than that. AT&T also sell those directly to us (or an Enterprise).
T-Mobile use a smaller variant of this same product (branded as CellSpot), but I understand they are also rolling out a smaller Ericsson picocell. Unlike Verizon/AT&T, T-Mobile don’t support a self-install business model for the Enterprise. Instead, their “Bring Your Own Connectivity (BYOC)” program involves connecting their own fibre to every building (SLA within 200 days), even when there is already 10 Gbps Internet broadband in service.
Sprint have discontinued their 3G Airave femtocells in favour of a new LTE only product (branded as MagicBox, both supplied by CommScope) but this is currently only available in three small markets. Their website hasn’t quite caught up with that yet. Sprint are the only US network which doesn’t yet support VoLTE (Voice over LTE) and so an LTE only in-building solution would fall back to external 3G to handle voice calls. A multi-mode 3G/4G MagicBox would solve the problem.
How quickly can these systems be installed?
We can deploy a solution within a week that supports AT&T and/or Verizon but find both T-Mobile and Sprint problematic at the moment. If you want to plug femtocells into a DAS system, the residential Alcatel-Lucent/Nokia units that T-Mobile use can’t be physically opened up (due to anti-tampering security) and don’t have an option for an external antenna.
Verizon and AT&T require a re-transmission agreement (also known as a rebroadcast agreement) to be signed with the local network team. Anytime you power up a DAS system (not standalone small cells) you need this in place. We’ve found that to be a fairly painless process so far because we already work closely with their national small cell teams.
What about larger or busier buildings?
Enterprise femtocells are effective in commercial buildings up to 100,000 sq feet. For residential apartment complexes, where there are relatively fewer users, they can handle up to 400 or even 500,000 square feet buildings serving up to 2,000 users. Small cell solutions with centralised controllers, such as SpiderCloud E-RAN, can handle medium to larger buildings with higher traffic demands, but are typically used to improve coverage for just one carrier.
The largest, busiest buildings justify the higher expense of DAS and the larger basestations to drive it. We see strong demand for lower cost, multiple-operator in-building wireless solutions that the industry isn’t fully addressing today.
And finally, any thoughts about CBRS?
This is a fascinating opportunity and definitely one to watch. I expect the main issues are around timescale and device compatibility. We already have a hard time convincing some people that LTE-only systems are enough today.
I think it will take a few years before there are enough CBRS compatible smartphones for it to become mainstream. In the meantime, in-building systems need to support voice and data for the vast majority of smartphones in use today.
Our thanks to Sina Khanifar for sharing his thoughts and experience so openly with us. For more information about RSRF, visit their website.