IEEE
KW
Section
Vehicular
Technology
Chapter
Distinguished
Lecture
Cognitive
Radio
for
Wireless
Communications:
Concepts
and
Applications
Abstract:
To
meet
rapidly
growing
traffic
demands
and
accommodate
a
large
number
of
devices,
more
radio
spectrum
is
needed
for
future
wireless
communications.
Considering
the
scarcity
of
radio
spectrum,
it
is
needed
to
enhance
the
utilization
of
radio
spectrum
licensed
exclusively
to
specific
users.
In
cognitive
radio,
an
unlicensed
user,
called
a
secondary
user,
is
permitted
to
access
the
spectrum
allocated
to
a
licensed
user,
called
a
primary
user.
When
the
primary
and
secondary
users
transmit
their
signals
simultaneously,
interference
occurs
at
both
users
which
degrades
their
performance.
Interference
at
the
primary
user
can
be
avoided
by
spectrum
sensing
technique
which
prohibits
a
secondary
user
from
transmitting
its
signal
when
it
detects
a
primary
user’s
signal.
Also,
interference
level
at
the
primary
user
can
be
limited
below
a
certain
threshold
by
spectrum
sharing
technique
in
which
the
secondary
user
adjusts
its
transmit
power
accordingly.
Some
recent
results
on
cognitive
radio
are
introduced,
and
its
applications
and
future
research
subjects
are
shown.
Jae
Hong
Lee
received
BS
and
MS
degrees
from
Seoul
National
University,
Korea,
and
Ph.D.
from
the
University
of
Michigan
at
Ann
Arbor
in
1986.
He
was
with
AT&T
Bell
Laboratories
and
joined
Seoul
National
University
for
which
he
is
currently
a
professor
and
served
as
Director
of
Institute
of
New
Media
and
Communications,
and
Chairman
of
EECS
Department.
His
research
activities
are
in
physical
layer
wireless
communications
such
as
MIMO,
cooperative
diversity,
cognitive
radio,
energy
harvesting
and
HetNet,
and
their
applications
to
5G
wireless
systems.
He
served
as
chairman
of
the
committee
for
coordination
of
3G
wireless
communication
technology
development
in
Korea
and
was
principal
investigator
in
communications
for
ITS
Grand
Design
Project
of
the
Korean
government.
His
laboratory
was
designated
as
a
National
Leading
Research
Laboratory
by
Ministry
of
Science
and
Technology
of
Korea.
He
was
President
of
the
Korean
Society
of
Broadcast
Engineers,
President
of
the
Institute
of
Electronics
Engineers
of
Korea,
and
President
of
the
IEEE
Vehicular
Technology
Society.
He
is
an
IEEE
Fellow
and
IEEE
VT
Society
Distinguished
Speaker.
He
is
a
member
of
the
National
Academy
of
Engineering
of
Korea
and
a
member
of
the
Korean
Academy
of
Science
and
Technology.
