The three key differentiators between DAS and Small Cells for Enterprise

buildingsRecently, we looked at the need for a wider business perspective to deliver better in-building cellular service. Here, we explore the three major business differentiators between Small Cell and DAS (Distributed Antenna Systems) solutions.

The DAS industry isn't standing still, and we can see more investment from different product sectors in addition to supporting planning and configuration tools. It's a sign that the industry is waking up to the need for improved in-building service, which aren't being met by a traditional outdoor only approach.


DAS systems are perceived as expensive and fit only for the largest buildings

Distributed Antenna Systems (DAS) deployments are major projects taking weeks or months, and involving intensive RF engineering, RF testing and project management. More modern designs have reduced the impact by using smaller cables rather than thick co-ax and more intelligent RF antenna. Dedicated wiring is required throughout the building, specialist engineers need to be involved to design, test and optimise the system.

This makes these systems relatively expensive and inappropriate for smaller buildings or providing partial coverage. A typical size of 300,000 square feet is often quoted as the lower limit for a DAS business case. Bill Hogg, VP Engineering at AT&T, suggests a crossover point of around 30 storey buildings, above which DAS is more appropriate than Small Cells.

Three specific business issues continue to crop up and hold back take-up:

  • Total cost of ownership, including approval and permit cycles
  • System flexibility and multi-Operator support (cost sharing due to high cost)
  • Rapid deployment

Lower cost DAS systems

DAS vendors are responding with lower cost products. These are still multi-operator capable, connecting to multiple macrocell basestations from different operators co-located in a central machine room. Dark fibre distributes the RF signals to each floor, from where coax or dedicated CAT5 cable connects to remote radio heads. Multiple venues can be served from the same central office where dark fibre is available to connect and within a few kilometres range.

Last week, Kathrein, the large German antenna manufacturer, launched their lower cost K-BOW solution. Frank Oehler, Head of Business Development, explained to me how their approach can reduce the cost and complexity by simplifying the RF design, deskilling the installation process and enabling more remote configuration and management – reducing the number of site visits required after installation. Where dark fibre is available to multiple sites, this could allow a central location to power several isolated buildings across the city – a sort of "Mini Cloud RAN" architecture.

Other vendors, such as TE Connectivity, have similar technical solutions and I fully expect others to be announced at Mobile World Congress next week.

These DAS solutions differ from Ericsson's Radio DOT and Huawei's LampSite which are tied to a single operator.

These systems are still comparatively pricey because they require full basestations in additional to the high capacity fibre connections and remote antenna. A business case study for the Small Cell forum found that DAS systems become competitive for larger buildings when the costs are shared between multiple operators.


Figure 1: Small Cell vs DAS business case, RealWireless (for Small Cell Forum)

By contrast, Small Cells have a very low incremental cost and are flexible and scalable from single units up to a hundred or more small cell within a building using a system approach. With enterprise small cells, an operator can cost-effectively serve one or more tenants inside of a multi-tenant office building. Once the initial cost of integrating a Small Cell gateway has been made, the additional cost of each site is minimal. Backhaul can use existing wireline broadband Internet services.

Multi-Operator Support

We've looked at the technical options for a multi-operator Small Cell deployment, but I think it would be fair to say that these aren't being adopted today.

Where DAS systems have an advantage is that they can cost share between multiple operators, reducing the cost per operator to a lower price point for large and complex sites. But, multi-operator could also be a business dis-advantage. DAS needs multi-operator support to cost-share expensive deployments, causing deployments to take months or years to complete.

Some would argue that multi-operator support is mandatory. Public venues serving allcomers may find it highly advantageous to provide good customer service to everyone, regardless of which network operator they use.

The reason for the uptake in small cells for enterprises is that operators can achieve increased loyalty and attract more customers where they provide good service, over and above others. An example of this would be where an office or facility has excellent service from one network above others. Word quickly gets round about which service provider to use, resulting in contracts being transferred by individual customers in addition to any bulk contract in place.

Flexibility & Ease of Deployment

Ronny Haraldsvik, CMO of Spidercloud, tells me there has been a strong reaction to the company's case study findings over the last year that a scalable system of small cells can be deployed in hours or days. He reports surprise, disbelief and concerns from operations managers that they may be set expectations that cannot be met, but is confident that such short timescales can be achieved. The big obstacle is overcoming operator operational procedures that are based on DAS installation timelines measured in months, with tight control from RF engineering teams.

Backing up this rapid deployment theme, Spidercloud announced what they call "EASY-30" program, comprising of simple tools and deployment flexibility using Ethernet and VLAN, to identify, verify and commission live operations within 30 days of a customer order.

The factors which are changed to enable this include:

  • simplify the initial planning/design from weeks to days using a pre-sales planning application (E-RAN estimator)
  • reuse existing in-building Ethernet where possible and the ability to deploy using a virtual LAN approach.
  • simplify installation to any approved electrical or Wi-Fi technician
  • automate the RF configuration, installation and ongoing network optimisation using SpiderCloud SON

Other in-building planning tools are still needed, such as iBwave's latest iPad /Android app which caters for in-building design of Wi-Fi, Small Cells and DAS.

While we are seeing these factors also being applied to DAS systems, I'd still expect the total cost of ownership to be lower for Small Cell systems, as pointed out by the Small Cell Forum's studies shown above. The high level of automation already developed for the residential Small Cell market combined with low cost of standard Ethernet broadband will be hard to beat.

DAS will win out for larger sites where multi-operator capability is seen to be more important, or for large single tenant businesses, because the installation costs can then beshared between operators.


There is clearly a pent-up demand for better in-building mobile service that is not being addressed by outdoor or older antenna technologies. Technical advances, across all of the Small Cell, DAS and Wi-Fi sectors seek to address that. More cost effective solutions, both CAPEX and OPEX, are becoming available.

The reduced total cost and rapid deployment will make this sector more attractive than before. There remains some debate about whether multi-operator support is an advantage or not – there's no straight answer and it depends on each specific use case. Operations departments remain to be convinced about how quickly and easily these systems can be deployed.

What is certain is that within the next few years, we should reasonably expect better indoor service from our mobile networks. This is something that is critical to consolidate and grow the "always on connectivity" which has now become an essential part of our lives.

This will definitely be a hot topic at next week's Mobile World Congress.

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#1 MN said: 
Your blog offers a treasure of information on small cells. Congrats. The comments from Spidercloud above perhaps confirm some commentary I have heard from one Wifi vendor. Smallcell deployment in the Enteprise will need to get simplified so that a VAR could do it, and not just an operator. Only then will we see a ramp up in the rollouts.
+1 Quote 2014-03-16 00:15
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