[grc] LTE-U; Impact on Community Radio & WI-FI ?

[juice at whidbey.com]

With the cell industry gobbling up spectrum for data faster then the
FCC can make more available, now Cell wants to off load traffic on to
local unlicensed WI-FI.  I am aware of several 5Ghz STLs already
experiencing congestion with interment-ant interference issues. With
Vo-LTE and other data hungry apps on the way, What can be organized to
keep community WI-FI and Community Radio from getting run over by the
big guys?
Tom Voorhees

 http://www.rcrwireless.com/20150422/test-and-measurement/lte-unlicensed-3-things-to-know-tag6
[1]

LTE-UNLICENSED: 3 THINGS TO KNOW

	The use of LTE over unlicensed spectrum has gained significant
interest within the industry, with multiple wireless operators
interested in boosting their network capacity and speed by aggregating
their licensed LTE spectrum with unlicensed spectrum at 5 GHz. 

	Verizon Communications brought together a number of major wireless
vendors last year to explore the technical aspects of LTE-U. The LTE-U
Forum was formed by Verizon along with Alcatel-Lucent, Ericsson,
Qualcomm and Samsung put together a series of technical documents on
the technology and its workability with Wi-Fi. The documents
available on the site [2] include a coexistence study as well as
minimum requirements for both user equipment and base stations for
LTE-U. 

	Here are three things to keep in mind in discussions as discussions
of LTE-U progress: 

	– GLOBAL REQUIREMENTS FOR LTE IN UNLICENSED SPECTRUM AREN’T
UNIFORM. In most of the world, the framework for making LTE-U work is
generally left up to the standards bodies and the industry. However,
in Japan and Europe, there are regulatory requirements to adopt a
“listen before talk” or “listen then talk” (LBT or LTT) scheme
to minimize interference with Wi-Fi. 

	According to Qualcomm [3], “the deployments in countries such as
U.S., Korea, China and India will use [LTE Release] 10/11/12 with
coexistence features such as [carrier sensing adaptive transmission],
and regions such as Europe and Japan that have LBT requirements will
use [LTE Release 13] LAA – Licensed Assisted Access.” 

	Sanjeev Athalye, product manager for Qualcomm Research’s WWAN
projects, said that the differences in the regulation of LTE-U are
likely to impact deployment timelines. 

	- THERE ARE MAJOR CONCERNS AROUND CO-EXISTENCE AND THE POTENTIAL
IMPACT OF LTE-U ON WI-FI AT 5 GHZ. CableLabs [4], among others, has
tested the coexistence of Wi-Fi and LTE at 5 GHz and found reasons to
be concerned about how well LTE-U will play with Wi-Fi even with
fairness mechanisms in place. (For CableLabs’ take on LBT [5] and
duty cycling [6], check out these blog posts [7].) 

	Nokia, which is developing pre-standards LTE-U small cells [8] for
deployment by T-Mobile US, has also done testing that showed
significant impact. In simulation, Nokia research [9] found
that “LTE system performance is slightly affected by coexistence
whereas Wi-Fi is significantly impacted by LTE transmissions. In
coexistence, the Wi-Fi channel is most often blocked by LTE
interference, making the Wi-Fi nodes to stay on the listen mode more
than 85% of the time. This reflects directly on the Wi-Fi user
throughput, that decreases from 50% to ~100% depending on the
scenario.” 

	The LTE Forum’s testing, however, concluded that with coexistence
mechanisms in place, LTE-U’s impact on Wi-Fi can be minimized. The
group also found that “in general, the observed gain of LTE-U was
smaller in indoor environments relative to outdoor.” 

	“When LTE is simply deployed in unlicensed spectrum without any
coexistence mechanism, it was observed that LTE can cause significant
performance degradation on coexisting Wi-Fi,” the group
acknowledged. “However, when LTE-U is deployed with reasonable
coexistence mechanisms … it was shown that LTE-U behaves as a
comparable or better neighbor to Wi-Fi compared to Wi-Fi as a neighbor
while LTE-U significantly outperforms the replacing Wi-Fi
deployment.” 

	Operators, Athalye said, “have told us, and we understand, they
have no interest in being a sore thumb” for the Federal
Communications Commission and the Wi-Fi community and that if Wi-Fi
interference results in complaints from the Wi-Fi community, then the
FCC is likely to clamp down on LTE-U. 

	Qualcomm is already responding to those concerns with implementing
coexistence measures. As Athalye explained it, the multiple channels
and large amount of spectrum available at 5 GHz means that “the base
stations can scan the frequencies and look for bands or channels that
are unused, or if they cannot find that, it will camp on a channel
that has the lowest utilization.” 

	- PRODUCTS ARE ALREADY IN DEVELOPMENT THAT MAY APPEAR THIS YEAR, WITH
DEPLOYMENTS EXPECTED OVER THE NEXT TWO YEARS.  

	Athalye noted that T-Mobile US and Verizon Wireless have both made
statements about trials, and Ericsson has made statements about
product offerings, with a timeline toward the end of 2015 in mind and
enabling commercial launches in the first half of next year. (Qualcomm
and Ericsson have already been demonstrating LTE-U [10] for operators
including Verizon Wireless, T-Mobile US and SK Telecom.) For
listen-then-talk implementations with LAA, he added, the standard is
expected to be completed in the first half of 2016 with reasonable
expectation for products in the first half of 2017. Athalye expects
that the “first incarnation will support 2x to 3x carrier
aggregation,” reflected by speeds of 450 megabits per second up to
600 Mbps. 

	Athalye will be speaking on the topic of LTE-U at the LTE Innovation
Summit [11] in Del Mar, Calif. this week.

 

Links:
------
[1]
http://www.rcrwireless.com/20150422/test-and-measurement/lte-unlicensed-3-things-to-know-tag6
[2] http://www.lteuforum.org/documents.html
[3] https://www.qualcomm.com/invention/technologies/lte/unlicensed
[4] http://www.cablelabs.com/will-wi-fi-have-to-share-the-waves/
[5]
http://www.cablelabs.com/wi-fi-vs-eu-lbt-houston-we-have-a-problem/
[6] http://www.cablelabs.com/wi-fi-vs-duty-cycled-lte/
[7] http://www.cablelabs.com/news-events/blog/page/3/
[8]
http://www.rcrwireless.com/20150223/mobile-minute/t-mobile-us-nokia-plan-lte-u-small-cells-tag4
[9] http://research.nokia.com/publication/12644
[10] http://www.ericsson.com/news/1893104
[11] http://www.lte-summit.com/index.php