Since the birth of the iPhone in 2005 and the resulting wireless data demand, in-building wireless (IBW) systems have gone from curiosity to luxury to amenity and, finally, to utility status. Most recently, IBW communications —DAS, public safety and Wi-Fi — have crossed the chasm from being seen as a technology to being accepted as an intelligent building solution, RF Connect marketing executive Bob Butchko told DAS Bulletin.
“Today, the commercial real estate industry recognizes that having a positive in-building smartphone or tablet experience is critical to tenant acquisition and retention,” Butchko said. “It is commonly accepted that most commercial, residential or office buildings need, or will need, some form of in-building wireless enhancement if only for satisfying government-mandated public safety radio regulations.”
But that success has led to its own challenge: Who is going to pay for this solution?
As DAS moves from amenity to utility, building owners must figure out how to deploy and pay for wireless within their buildings. Carriers, which deploy DAS in hundreds of public venues and for thousands of their major accounts, are not much interested in the 1.2 million or so commercial buildings, most of which are not strategic to their business plans. Tower companies work on the same ethic; if the carriers don’t see a site as strategic, the tower companies won’t build there.
The only option left for most building owners, unless their building has a very high profile, is to purchase and deploy the IBW systems, which sets up a new dynamic. Building owners who are not knowledgeable about DAS are pressed into the position of project managing a wireless deployment, interfacing with carriers, the building tenants, municipality, general contractors, system integrators, OEM manufacturers, financial/legal experts and consultants. Butchko points out that just negotiating with the carriers is fraught with complications.
“[You need to] go to the carriers and find out if the building is strategic or not. What would they be willing to do? Would they provide a base station? Would they want to put antennas on the roof?” Butchko said. “What are their restrictions? Any DAS plan must be cleared by the carriers.” He recalls a DAS that was built at a hospital, and the carrier came by and told them they couldn’t do it.
To assist building owners in deploying an indoor wireless system, at RealComm IBcon 2013 on June 12, RF Connect launched a new service, known as the RFC Connection, which elevates RF Connect from the status of mere integrator to business partner and consultant for the building owner.
“Instead of skinnying down the bid to beat the competition, we will be trying to put the wireless systems that are really needed in the building for the lowest cost and best results over the long term for the client,” Butchko said.
The RFC Connection offers an end-to-end integrated package of services, where it assesses, designs, implements and provides long-term support for the wireless systems, as well as serving the building owner as a partner and advocate.
“The industry needs a new approach where a third party looks out for the building owners’ interests,” said Butchko. “Effectively, the burden of providing and supporting cellular coverage, Wi-Fi and all in-building wireless capabilities is contractually outsourced to RF Connect. All this adds up to a much better outcome for the owner.”
— Consumer femtocells and their higher power cousins, enterprise and public-access femtocells, provide coverage in hard-to-reach areas. But they do not address the mobile data capacity explosion. Why? Because they cannot be used in places where the demand for mobile data is actually exploding!
The demand for mobile data is highest in places where hundreds or thousands of people congregate, such as large shopping centers and large office buildings. Using a single small cell, irrespective of its power or capacity, will not help operators meet the demand for data. All that the operator will get is dissatisfied subscribers, who can see five bars of coverage, but merely get a few hundred kilobits of data.
To address the mobile data explosion, operators need a small cell system that enables them to:
This is a tall order. The indoor RF environment, especially in large multi-story buildings is very challenging. In a dense deployment, a handset can see several small cells at the same time. Because of fast fading, a handset may handover from one cell to another several times a minute without moving at all.
So, is a dense small deployment not possible? Yes and no. It depends on the architecture adopted. Broadly, four architectures have been proposed in the industry:
1) Femtocells connected to a Home Node B Gateway (HNB-GW) with hard handover
2) Small cells connected to a Home Node B Gateway (HNB-GW) with soft handover using “Iurh”
3) Pico-cells connected to a traditional 3G Radio Network Controller (RNC)
4) Small cells connected to a small local controller. Local controller connects to the core network as single HNB.
The first option, hard handover of femtocells, has been trialed by many operators and most agree that it is not practical to deploy more than 5-10 femtocells in a large building.
Many suppliers who initially proposed the first architecture are now moving to the second architecture. They are implementing soft handover using a variation of the Inter-RNC handover protocol called Iurh. Since soft handover requires synchronization between small cells, some suppliers are building small cells with expensive oven-controller oscillators. All handover signaling goes over the backhaul link and can become a significant expense. And there is no way for an operator to locally offload data traffic without breaking inter-small cell mobility. Products based on this architecture are currently in development.
The third option, using pico-cells connected to a RNC, is another way to do soft handover between small cells. This architecture is often offered by macro cellular infrastructure suppliers, who are able to scale down their macro NodeBs and reuse existing RNCs. It can be attractive if an operator requires a small number of small cells, but in the case of high-density deployments, the cost of RNC ports can add up. Further, this architecture does place very stringent requirements on backhaul, and it unclear how SON functionality will be implemented.
In the fourth architecture, all small cells in a building are connected to a small local controller over Ethernet. This controller is responsible for managing mobility, interference and SON. It aggregates all the traffic and connects to a HNB gateway as a single HNB would using standard Iuh signaling. All inter-small cell mobility events stay inside the building, and do not load the backhaul link or the HNB gateway. The local controller acts as the master-clock and synchronizes all the small cells, eliminating the need for expensive oscillators in every small cell. If an operator wants to offload data traffic locally or integrate with enterprise applications, it can do so using the local controller. Some operators are working on enterprise applications that use the network intelligence that can be accessed at the local controller.
SpiderCloud’s 3G small cell solution is based on the fourth architecture. Operators have used it to deploy as many as 65 small cells in a 16-story office building, with thousands of subscribers and hundreds of thousands of inter-small cell handovers daily and the technology is now ready to provide coverage, capacity and new applications in even larger buildings.
This blog was based on a speech by Jain at the LTE LATAM 2013 conference in Rio de Janeiro, Brazil on April 16, 2013. Jain joined SpiderCloud in September 2011. Prior to SpiderCloud, he was vice president of marketing, sales and service for Airvana’s CDMA femtocell business. During his 10 years at Airvana, which included the company’s inception, Jain held several leadership roles in marketing, business development and sales for 3G EVDO macro cellular products and femtocells. Prior to Airvana, Jain held both technical and business positions at Qualcomm, Ericsson, and McKinsey & Company. He holds an MBA from MIT’s Sloan School of Management, an MS in Electrical Engineering from University of California at Irvine, and a B.Tech in Electrical Engineering from the Indian Institute of Technology, Bombay. www.spidercloud.com/