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.