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INTERNATIONAL AGENTs
SECTION
Unlicensed Spectrum
Open the Door
to Resellers
By
Tara
Seals
F
aced with the scarcity, cost
and difficult propagation
characteristics of the re-
maining greenfield licensed
spectrum, one of the first
steps in achieving a next-
gen wireless network vision that can
stand up to the growing thirst for rich
content will likely be the use of unli-
censed LTE approaches.
LTE-U, as it’s known, will allow opera-
tors to extend and enhance their LTE
coverage and network performance –
but it also paves the way for higher-mar-
gin MVNO services that could reinvigo-
rate the global wireless resale market.
Unlicensed LTE approaches typically
aggregate Wi-Fi and unlicensed spec-
trum in order to get the maximum ben-
efit out of Wi-Fi’s heightened bandwidth
throughput – while leveraging LTE links
for signal control and management.
One approach is now under develop-
ment by 3GPP for standardization in
Release 13 – to be known as License-
Assisted Access (LAA). That standard
is expected to be finalized this summer.
Heavy hitters such as Verizon and Qual-
comm are embracing the approach.
It works like this: The LTE control
channels, and primary uplink/downlink
channels, are handled in the licensed
bands, using LTE-A Carrier Aggregation
(CA) to do channel bonding between
the licensed and unlicensed downlinks,
and possibly the uplinks in follow-on
iterations. The purpose of the unli-
censed bands is to provide additional
data plane performance – a data plane
boost, in effect.
To minimize interference, it has a
“listen before talk” (LBT) mechanism,
which is the same approach that Wi-Fi
uses to share the unlicensed spectrum
with other Wi-Fi systems.
“LTE in unlicensed spectrum will be
an important part of the network densi-
fication initiatives to increase network
capacity, using small cells that sup-
port LTE in 5GHz,” said Adam Koeppe,
vice president of network technology
planning at Verizon. “LTE in unlicensed
spectrum also offers an evolutionary
path based on specifications being
developed in global standards groups
(3GPP), to continuously enhance
the capabilities of LTE in unlicensed
spectrum. For example, a future 3GPP
release (3GPP Release 14) will allow
uplink operation using 5GHz.”
While LAA does have LBT involved,
there are still concerns from other stake-
holders when it comes to interference.
With LAA, LTE is operating in both the li-
censed bands and within the same spec-
trum that Wi-Fi uses – so there are two
signals in the same band, and therefore
the potential for coexistence problems.
To address this, Verizon and all other
LTE-U Forum members are collaborat-
ing with the Wi-Fi Alliance (WFA) in the
development of a very comprehensive
coexistence test plan geared toward the
lab validation of coexistence with Wi-Fi.
But, there is also another technology
approach that could save the day.
24
Channel
Vision
|
May - June 2016