On Wednesday, the world’s largest cellular network vendor introduced a radio that can fit in the palm of your hand and hook up to a full-size base station via conventional LAN cables. The so-called 'Radio Dot System', due to ship late next year, will let carriers fill large and medium-sized buildings with strong voice and data signals while keeping their equipment and management costs low, Ericsson said.
While traditional cellular networks are built around large outdoor “macro” cells, most mobile use happens indoors. To accommodate all that voice and data demand, mobile operators have long installed DAS (distributed antenna systems) throughout buildings and more recently have used small indoor cells, which are miniature versions of the macro cells on towers outside.
However, buying and installing the specialized DAS equipment is expensive, and managing and coordinating a collection of small individual cells around a building is complicated, Ericsson CTO Ulf Ewaldsson said. Among other things, small cells sharing the same spectrum with macro base stations have to turn down their power if they are in danger of interfering with the bigger cell, he said.
Ericsson plans to solve those problems by putting the core components of a macro cell into a building and spreading the radio parts of the cell throughout the rooms as Radio Dots. The Dots are disk-shaped units that weigh just 300 grams. The core unit, called the baseband, will be able to manage as many as 96 Radio Dots as one large cell. Another radio platform, called an IRU (indoor radio unit) will sit in between the dots and the baseband and house some other radio components. The system can be used for both 3G WCDMA and 4G LTE.
“We’re splitting the radios in a new way,” Ewaldsson said. “We put as little as possible in a radio dot that can do the radio transmission and the antenna piece on a wall.”
As demand for coverage or capacity in the building grows, carriers will have many options for scaling up the system because all the dots are logically managed as one base station, Ewaldsson said. Also, the full-size macro baseband that the dots share will have a complete set of features, instead of the subset that’s included in small cells, and can be more easily updated, he said.
Ericsson claims a Radio Dot System could cut installation time by 70 percent and capital cost by 60 percent compared with a DAS. For one thing, the links between elements will use the same type of Category 5, 6, and 7 copper cables used for conventional LANs, which are less expensive than the fiber-optic wiring typically used with a DAS, Ewaldsson said.
Enterprises may look to the Radio Dots when it comes time to replace a DAS, Ovum analyst Daryl Schoolar said. The system may also be an attractive DAS alternative because it could economically be deployed in just part of a building, rather than requiring the scale that a DAS needs, he said. But there are also other ripe opportunities for boosting indoor coverage, he said.
“It really could cover a lot of areas out there today,” Schoolar said. “The prime real estate for the small cell is really going to be indoors ... because so much stuff goes on indoors.”
However, the very BYOD trend that is bringing employees’ own mobile devices into the workplace could make Radio Dots less attractive in some cases.
“What Ericsson is showing is a very operator specific solution, but if you have a deployment area where workers are spread out among four different mobile operators, the value of that solution is diminished,” Schoolar said. “Also it locks a business into a specific operator, and that business may want more flexibility.”
With a DAS, by contrast, it’s typically easier to bring multiple carriers into the system, said Peter Jarich of Current Analysis. A Radio Dot System would be easier to install as an overlay, but in new construction, including a DAS is not as big a burden, Jarich said.
At least two major carriers are interested in Radio Dots. AT&T is participating with Ericsson in Wednesday’s announcement, and Verizon Wireless also plans to test the system. “We have seen it, we like it and we look forward to testing and trialing it,” Verizon spokesman Tom Pica said via email.
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