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Many Questions About DAS, Small Cells & Spectrum At 4G World

By Mike Collado
November 3rd, 2012

4G World 2012

Team SOLiD enjoyed a busy and productive week during 4G World in the Windy City in spite of Hurricane Sandy which affected travel for many exhibitors, presenters and attendees from the East Coast, making for a much cozier event than organizers had envisioned.

(BTW, please considering joining SOLiD and our employees by making a contribution to a charity of your choice that is working to support the hurricane relief and recovery efforts to help our neighbors, brothers, sisters and four-legged friends. Here’s a list of highly-rated charities that are responding. Thank you!)

Nonetheless, we connected with Michael Howard at Infonetics and Joan  Engebretson from TMCnet who has since published a column about our vision to converge DAS and Optical Transport to form the foundation for next-generation DAS networks.

We braved the chilly night air to catch up with partners and peers at a rooftop party hosted by our partner and friends at iBwave. Plus we got our Chicago-style deep dish pizza fix at Lou Malnati’s.

SOLiD had the privilege to present on the the “In-building 4G Wireless Solutions for Venues” panel along with Jim Parker from AT&T’s Antenna Solutions Group, Mario Bouchard from iBwave and Emil Olbrich from NIST (agency of the U.S. Department of Commerce). Based upon the panel’s interaction with attendees, it’s clear that there are many fundamental industry questions about DAS, Small Cells and Spectrum.

DAS and WiFi and Small Cells (oh my…)

The key problem for wireless operators is satisfying customer needs given a “data tsunami” that Jim Parker quantifies as having 20,000 percent growth. With customers now uploading more content than they’re downloading and the bulk of cellular traffic occurring indoors (80% cites Mario Bouchard), the macro network can not efficiently service users in high-density areas. Given the tremendous uptick in use, it is necessary to build the network from the “inside-out” to compliment macro network approach of “outside-in.”

For large public venues (think: hospitals, college and corporate campuses, sports venues, convention centers and the like), DAS, WiFi and Small Cells are identified as the go-to solutions capable of scaling to bring more capacity indoors.

Which One To Use?

During a case study earlier this year at the ACUTA Annual Conference, a panelist pondered whether WiFi could be used to support smartphone users across the campus at Indiana University. While it’s tempting to look to unlicensed spectrum and existing investment in deploying and supporting WiFi Access Points, the issue is that the cellular band is very large compared with WiFi. On the other hand, wireless operators do look to WiFi as a complimentary strategy to offload data to conserve RAN.

Wireless Spectrum

Meanwhile, having been fed a steady diet of Small Cells at 2012 industry events, attendees at 4G World questioned whether Small Cells – and most folks are referring to a femtocell or picocell – will replace DAS as a more cost-effective technology. (To inject a little levity, Bouchard quipped that “small cell” is a buzzword that attracts a lot people to conferences)

Today, a femto can’t compete with DAS because it does not provide a neutral host solution. And even if you cobbled together multiple femtos required for each carrier, you’d need a bunch of them and they’d not scale as bandwidth requirements increase. Besides, all these boxes would be aesthetically unappealing.

But the key reason, as we alluded to above with WiFi, has to do with spectrum. Remember, the cellular band is very large: dropping a PICO or eFEMTO for this entire band is not possible since the typical pico chip only handles 20Mhz up and 20Mhz down.

SOLiD CTO, Saeed Anwar, cautions that supporting 4 major wireless operators (AT&T, Sprint, Verizon and T-Mobile) does not mean you need just 4 picos. Rather, each wireless operator has a spectrum across the entire band. For instance, Verizon Wireless has 4 bands (700, 850, 1900 and 2100 MHz). However, 1900 is a very large band (65Mhz up and 65 Mhz down) and is split in many sub-bands. These sub-bands may also vary by region on operators owning specific sub-bands. So, Verizon alone could have 700 upper c as one pico, 850 as a second pico, variations in 1900 picos because of the large spread and a 2100 AWS pico. (There are also variations in 700 and AWS but not to such a big scale as 1900)

What Is A Small Cell, Really?

The answer, it seems, depends…

Bouchard referred to Small Cells as a big bucket of solutions. Meanwhile, Parker cited DAS as being the original Small Cell.

The Small Cell Forum was originally focused on femtocells. However, our discussion with AT&T’s Gordon Mansfield, who was recently named the new chairman of the Small Cell Forum, reveals a  migration in thinking. Specifically, Mansfield shared that the Small Cell Forum will distinguish between residential (femto & wifi) and enterprise cells going forward.

Michael Howard at Infonetics was similarly adamant at 4G World that small cells and residential (femto & wifi) should not be in the same bucket.

So it seems reasonable to categorize it like this: small cells are the technology deployments used to fill-in where enterprise needs are not being met by DAS and WiFi.

What do you say? Let us know if the comments section!


Entrance to the Exhibit Floor at 4G World 2012

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