The future of small cells, at least those with remote radio heads, will depend on a new networking concept known as “fronthaul,” according to a white paper by iGR. In 2014, the lion’s share of small cells will use remote radio heads, iGR said, which will be connected, or “fronthauled,” via fiber-optics to baseband units located in a central location that are then backhauled to the telephone network.
“The importance of providing a quality fronthaul/backhaul connection to a small cell cannot be overemphasized. The success, or failure, of the het‐net and small cell architecture depends on the operator’s ability to deploy fronthaul and backhaul that is appropriate to both the immediate data demand and what is forecasted,” according to iGR.
The move to a fronthaul-type architecture should be executed as a carrier deploys LTE, Iain Gillott, principal of iGR, told DAS Bulletin, but not every site is a candidate for fronthaul.
“There is a limit to how far the baseband can be away from the radio,” he said. “There can also be logistical reasons for avoiding fronthaul architecture.”
Fronthauling the baseband, which represents the virtualization of the radio access network, will save carriers millions of dollars in OpEx and CapEx globally, Gillott said.
“The cost to implement this architecture is not insignificant, but when you are putting in LTE you have a ton of work to do anyway. Especially with small cells, why not deploy fronthaul and get the benefits?” he said.
Fronthaul Fuels Deployment of SK Telecom Small Cell Network
The white paper goes on to highlight a system deployed by South Korea’s SK Telecom, which used SOLiD networking equipment and existing fiber to fronthaul an LTE small cell system.
Across South Korea, which is a small densely populated country, SK Telecom deployed 12,000 base station nodes and 80,000 remote radio heads in one year, using SOLiD’s fronthaul architecture. Since then the network has grown to 200,000 remote radio heads.
“SK Telecom is widely recognized as an innovator using the latest wireless technology. Because the South Korean market is in the forefront of technology it sheds some light on how the U.S. market is going to approach new technologies, such as small cells and RRH in order to fill in the holes and achieve network densification,” Mike Collado, SOLiD spokesman.
SK Telecom and SOLiD’s architecture used the existing legacy transport system complemented by two fiber rings for the LTE deployment. LTE remote radio heads were connected to SOLiD’s Infinity ACCESS RT and, in this deployment, the RRHs acted as small cells that were mounted on towers.
A single fiber ring simultaneously supports 2G/3G, 4G and Wi-Fi traffic: CPRI/OBSAI is used to support LTE traffic, Ethernet supports Wi-Fi, and E1/T1 is used for the legacy 2G/3G network. Up to 30 remote radio heads can be supported per base station node.
The base station nodes were located in a central office terminal. The transport system then provided connectivity back to the base station controller/radio network controller (BSC/RNC) and to the IP core, maximizing the re-use of existing fiber infrastructure.
SK Telecom deployed its initial network in about 12 month, which was half of the expected time. Operating expenses were reduced 5 percent in the first year and by 2014, SK Telecom expects 50 percent savings through reduced building lease and rental costs, reduced utilities, reduced maintenance and fewer truck rolls.
A copy of the iGR white paper can be downloaded directly from iGR’s website.
President and Founder,
— One of the main questions we have been asked recently is “what is a small cell?” This is an interesting question since it appears that different operators and vendors have different views on this. As the old adage goes, the answer is, “it depends on what you are selling!”
Before we get into what is and what is not a small cell, a funny story. A few years ago, I was at an analyst conference and asked a vendor (who shall remain nameless to protect the guilty) if their definition of HetNet [heterogeneous network] and, therefore, small cells includes Wi-Fi. The answer was a categorical “No,” since Wi-Fi was not considered part of the mobile operator’s managed network. A year later, at the same event and after the vendor had made a couple of Wi-Fi acquisitions, we asked the same question – this time the answer was “Yes.” The only difference was of course that the vendor now had a carrier Wi-Fi solution to sell.
The same trend seems to be affecting small cells as a whole. For example, some vendors do not consider DAS to be “small.” You will have guessed by now that it is mainly vendors that do not have a DAS solution that take this view. Similarly, femtocells are sometimes counted in small-cell TAM and forecast stats, and sometimes not. There is no consistency.
In order to define what a small cell is, and is not, it is worth going back and examining the problem we are trying to solve. HetNets, and small cells, came about because of the need to provide mobile RF coverage and/or capacity at specific points in a dense urban area, the assumption being that the existing tower-based cell sites were at capacity. So the vision for HetNets was that the cells would get smaller and become more tightly integrated, and managed, to provide the necessary capacity and coverage.
So with this in mind, what is a small cell? Basically, in my view, any RF network component that is not nailed to a tower! Since small cells are really macro cells with the power turned down and without a tower, this means that just about any of the range of RF solutions fit the definition. This would include remote radio head, Wi-Fi, DAS, femtocells and even home signal boosters.
I realize the last one on the list is a little controversial. The goal of the signal booster is to improve the in-building coverage – instead of being a managed part of the network as a cell is, the signal booster takes the available signal and juices it a little as it is retransmitted indoors. To the end user, the result is the same as a femtocell – five bars of coverage in the home. So the end result is the same as deploying a small cell, although of course the booster is not under the control of the operator and the operator does not get the “feel good” benefit from the consumer of the improved signal.
Sizing the entire small cell market is difficult, of course, if no one has the same definition. iGR’s approach is therefore to size each small cell market segment separately and define what is included and what is not. But from a macro perspective (pardon the pun), the small cell market is significant, especially because in reality it includes everything that is not nailed to a tower.
Iain Gillott, the founder and president of iGR and iGR Semiconductor Research, has been involved in the wireless industry, as both a vendor and analyst, for nearly 20 years. iGR was founded in 2000 as iGillottResearch in order to provide in-depth market analysis and data focused exclusively on the wireless and mobile industry. Before founding iGR, Gillott was a Group Vice President in IDC’s Telecommunications practice, managing IDC’s worldwide research on wireless and mobile communications and Internet access, telecom brands, residential and small business telecommunications and telecom billing services. Prior to joining IDC, he was in various technical roles and a proposal manager at EDS (now HP), responsible for preparing new business proposals to wireless and mobile operators. For more information, visit igr-inc.com