<s>
4G	B-Architecture
is	O
the	O
fourth	O
generation	O
of	O
broadband	B-General_Concept
cellular	O
network	O
technology	O
,	O
succeeding	O
3G	B-Architecture
and	O
preceding	O
5G	O
.	O
</s>
<s>
A	O
4G	B-Architecture
system	O
must	O
provide	O
capabilities	O
defined	O
by	O
ITU	O
in	O
IMT	O
Advanced	O
.	O
</s>
<s>
Potential	O
and	O
current	O
applications	O
include	O
amended	O
mobile	B-Application
web	I-Application
access	O
,	O
IP	B-Application
telephony	I-Application
,	O
gaming	O
services	O
,	O
high-definition	B-Device
mobile	B-Application
TV	I-Application
,	O
video	B-Application
conferencing	I-Application
,	O
and	O
3D	B-Algorithm
television	I-Algorithm
.	O
</s>
<s>
However	O
,	O
in	O
December	O
2010	O
,	O
the	O
ITU	O
expanded	O
its	O
definition	O
of	O
4G	B-Architecture
to	O
include	O
Long	O
Term	O
Evolution	O
(	O
LTE	O
)	O
,	O
Worldwide	O
Interoperability	O
for	O
Microwave	O
Access	O
(	O
WiMAX	O
)	O
,	O
and	O
Evolved	O
High	O
Speed	O
Packet	O
Access	O
(	O
HSPA+	O
)	O
.	O
</s>
<s>
However	O
,	O
it	O
has	O
been	O
debated	O
whether	O
the	O
first-release	O
versions	O
should	O
be	O
considered	O
4G	B-Architecture
.	O
</s>
<s>
The	O
4G	B-Architecture
wireless	I-Architecture
cellular	O
standard	O
was	O
defined	O
by	O
the	O
International	O
Telecommunication	O
Union	O
(	O
ITU	O
)	O
and	O
specifies	O
the	O
key	O
characteristics	O
of	O
the	O
standard	O
,	O
including	O
transmission	O
technology	O
and	O
data	O
speeds	O
.	O
</s>
<s>
4G	B-Architecture
has	O
speeds	O
of	O
up	O
to	O
150Mbit/s	O
download	O
and	O
50Mbit/s	O
upload	O
,	O
whereas	O
3G	B-Architecture
had	O
a	O
peak	O
speed	O
of	O
7.2Mbit/s	O
download	O
and	O
2Mbit/s	O
upload	O
.	O
</s>
<s>
4G	B-Architecture
technology	I-Architecture
constitutes	O
58%	O
of	O
the	O
worldwide	O
mobile	O
telecommunication	O
technologies	O
market	O
.	O
</s>
<s>
In	O
November	O
2008	O
,	O
the	O
International	O
Telecommunication	O
Union-Radio	O
communications	O
sector	O
(	O
ITU-R	O
)	O
specified	O
a	O
set	O
of	O
requirements	O
for	O
4G	B-Architecture
standards	O
,	O
named	O
the	O
International	O
Mobile	O
Telecommunications	O
Advanced	O
(	O
IMT-Advanced	O
)	O
specification	O
,	O
setting	O
peak	O
speed	O
requirements	O
for	O
4G	B-Architecture
service	O
at	O
100	O
megabits	O
per	O
second	O
(	O
Mbit/s	O
)	O
(=	O
12.5	O
megabytes	O
per	O
second	O
)	O
for	O
high	O
mobility	O
communication	O
(	O
such	O
as	O
from	O
trains	O
and	O
cars	O
)	O
and	O
1	O
gigabit	O
per	O
second	O
(	O
Gbit/s	O
)	O
for	O
low	O
mobility	O
communication	O
(	O
such	O
as	O
pedestrians	O
and	O
stationary	O
users	O
)	O
.	O
</s>
<s>
Since	O
the	O
first-release	O
versions	O
of	O
Mobile	O
WiMAX	O
and	O
LTE	O
support	O
much	O
less	O
than	O
1	O
Gbit/s	O
peak	O
bit	O
rate	O
,	O
they	O
are	O
not	O
fully	O
IMT-Advanced	O
compliant	O
,	O
but	O
are	O
often	O
branded	O
4G	B-Architecture
by	O
service	O
providers	O
.	O
</s>
<s>
On	O
December	O
6	O
,	O
2010	O
,	O
ITU-R	O
recognized	O
that	O
these	O
two	O
technologies	O
,	O
as	O
well	O
as	O
other	O
beyond-3G	O
technologies	O
that	O
do	O
not	O
fulfill	O
the	O
IMT-Advanced	O
requirements	O
,	O
could	O
nevertheless	O
be	O
considered	O
"	O
4G	B-Architecture
"	O
,	O
provided	O
they	O
represent	O
forerunners	O
to	O
IMT-Advanced	O
compliant	O
versions	O
and	O
"	O
a	O
substantial	O
level	O
of	O
improvement	O
in	O
performance	O
and	O
capabilities	O
with	O
respect	O
to	O
the	O
initial	O
third	O
generation	O
systems	O
now	O
deployed	O
"	O
.	O
</s>
<s>
As	O
opposed	O
to	O
earlier	O
generations	O
,	O
a	O
4G	B-Architecture
system	O
does	O
not	O
support	O
traditional	O
circuit-switched	B-Protocol
telephony	O
service	O
,	O
but	O
instead	O
relies	O
on	O
all-Internet	O
Protocol	O
(	O
IP	O
)	O
based	O
communication	O
such	O
as	O
IP	B-Application
telephony	I-Application
.	O
</s>
<s>
As	O
seen	O
below	O
,	O
the	O
spread	B-Architecture
spectrum	I-Architecture
radio	O
technology	O
used	O
in	O
3G	B-Architecture
systems	O
is	O
abandoned	O
in	O
all	O
4G	B-Architecture
candidate	O
systems	O
and	O
replaced	O
by	O
OFDMA	O
multi-carrier	O
transmission	O
and	O
other	O
frequency-domain	O
equalization	O
(	O
FDE	O
)	O
schemes	O
,	O
making	O
it	O
possible	O
to	O
transfer	O
very	O
high	O
bit	O
rates	O
despite	O
extensive	O
multi-path	O
radio	O
propagation	O
(	O
echoes	O
)	O
.	O
</s>
<s>
In	O
the	O
field	O
of	O
mobile	O
communications	O
,	O
a	O
"	O
generation	O
"	O
generally	O
refers	O
to	O
a	O
change	O
in	O
the	O
fundamental	O
nature	O
of	O
the	O
service	O
,	O
non-backwards-compatible	O
transmission	O
technology	O
,	O
higher	O
peak	O
bit	O
rates	O
,	O
new	O
frequency	O
bands	O
,	O
wider	O
channel	O
frequency	O
bandwidth	O
in	O
Hertz	O
,	O
and	O
higher	O
capacity	O
for	O
many	O
simultaneous	O
data	O
transfers	O
(	O
higher	O
system	O
spectral	B-Protocol
efficiency	I-Protocol
in	O
bit/second/Hertz/site	O
)	O
.	O
</s>
<s>
This	O
was	O
followed	O
,	O
in	O
2001	O
,	O
by	O
3G	B-Architecture
multi-media	O
support	O
,	O
spread	B-Architecture
spectrum	I-Architecture
transmission	O
and	O
a	O
minimum	O
peak	O
bit	O
rate	O
of	O
200	O
kbit/s	O
,	O
in	O
2011/2012	O
to	O
be	O
followed	O
by	O
"	O
real	O
"	O
4G	B-Architecture
,	O
which	O
refers	O
to	O
all-IP	O
packet-switched	B-Protocol
networks	I-Protocol
giving	O
mobile	O
ultra-broadband	O
(	O
gigabit	O
speed	O
)	O
access	O
.	O
</s>
<s>
In	O
the	O
mid-1990s	O
,	O
the	O
ITU-R	O
standardization	O
organization	O
released	O
the	O
IMT-2000	O
requirements	O
as	O
a	O
framework	O
for	O
what	O
standards	O
should	O
be	O
considered	O
3G	B-Architecture
systems	O
,	O
requiring	O
2000	O
kbit/s	O
peak	O
bit	O
rate	O
.	O
</s>
<s>
In	O
2008	O
,	O
ITU-R	O
specified	O
the	O
IMT	O
Advanced	O
(	O
International	O
Mobile	O
Telecommunications	O
Advanced	O
)	O
requirements	O
for	O
4G	B-Architecture
systems	O
.	O
</s>
<s>
The	O
fastest	O
3G-based	O
standard	O
in	O
the	O
UMTS	B-Protocol
family	O
is	O
the	O
HSPA+	O
standard	O
,	O
which	O
has	O
been	O
commercially	O
available	O
since	O
2009	O
and	O
offers	O
21Mbit/s	O
downstream	O
(	O
11Mbit/s	O
upstream	O
)	O
without	O
MIMO	O
,	O
i.e.	O
</s>
<s>
The	O
fastest	O
3G-based	O
standard	O
in	O
the	O
CDMA2000	O
family	O
is	O
the	O
EV-DO	O
Rev	O
.	O
</s>
<s>
This	O
article	O
refers	O
to	O
4G	B-Architecture
using	O
IMT-Advanced	O
(	O
International	O
Mobile	O
Telecommunications	O
Advanced	O
)	O
,	O
as	O
defined	O
by	O
ITU-R	O
.	O
An	O
IMT-Advanced	O
cellular	O
system	O
must	O
fulfill	O
the	O
following	O
requirements	O
:	O
</s>
<s>
Be	O
based	O
on	O
an	O
all-IP	O
packet	B-Protocol
switched	I-Protocol
network	I-Protocol
.	O
</s>
<s>
Have	O
peak	O
link	B-Protocol
spectral	I-Protocol
efficiency	I-Protocol
of	O
15bit/s	O
·Hz	O
in	O
the	O
downlink	O
,	O
and	O
6.75bit/s	O
·Hz	O
in	O
the	O
up	O
link	O
(	O
meaning	O
that	O
1Gbit/s	O
in	O
the	O
downlink	O
should	O
be	O
possible	O
over	O
less	O
than	O
67MHz	O
bandwidth	O
)	O
.	O
</s>
<s>
System	O
spectral	B-Protocol
efficiency	I-Protocol
is	O
,	O
in	O
indoor	O
cases	O
,	O
3bit/s	O
·Hz·cell	O
for	O
downlink	O
and	O
2.25bit/s	O
·Hz·cell	O
for	O
up	O
link	O
.	O
</s>
<s>
In	O
September	O
2009	O
,	O
the	O
technology	O
proposals	O
were	O
submitted	O
to	O
the	O
International	O
Telecommunication	O
Union	O
(	O
ITU	O
)	O
as	O
4G	B-Architecture
candidates	O
.	O
</s>
<s>
Some	O
sources	O
consider	O
first-release	O
LTE	O
and	O
Mobile	O
WiMAX	O
implementations	O
as	O
pre-4G	O
or	O
near-4G	O
,	O
as	O
they	O
do	O
not	O
fully	O
comply	O
with	O
the	O
planned	O
requirements	O
of	O
1Gbit/s	O
for	O
stationary	O
reception	O
and	O
100Mbit/s	O
for	O
mobile	O
.	O
</s>
<s>
Confusion	O
has	O
been	O
caused	O
by	O
some	O
mobile	O
carriers	O
who	O
have	O
launched	O
products	O
advertised	O
as	O
4G	B-Architecture
but	O
which	O
according	O
to	O
some	O
sources	O
are	O
pre-4G	O
versions	O
,	O
commonly	O
referred	O
to	O
as	O
3.9G	O
,	O
which	O
do	O
not	O
follow	O
the	O
ITU-R	O
defined	O
principles	O
for	O
4G	B-Architecture
standards	O
,	O
but	O
today	O
can	O
be	O
called	O
4G	B-Architecture
according	O
to	O
ITU-R	O
.	O
Vodafone	O
Netherlands	O
for	O
example	O
,	O
advertised	O
LTE	O
as	O
4G	B-Architecture
,	O
while	O
advertising	O
LTE	O
Advanced	O
as	O
their	O
'	O
4G+	O
 '	O
service	O
.	O
</s>
<s>
A	O
common	O
argument	O
for	O
branding	O
3.9G	O
systems	O
as	O
new-generation	O
is	O
that	O
they	O
use	O
different	O
frequency	O
bands	O
from	O
3G	B-Architecture
technologies	O
;	O
that	O
they	O
are	O
based	O
on	O
a	O
new	O
radio-interface	O
paradigm	O
;	O
and	O
that	O
the	O
standards	O
are	O
not	O
backwards	O
compatible	O
with	O
3G	B-Architecture
,	O
whilst	O
some	O
of	O
the	O
standards	O
are	O
forwards	O
compatible	O
with	O
IMT-2000	O
compliant	O
versions	O
of	O
the	O
same	O
standards	O
.	O
</s>
<s>
The	O
pre-4G	O
3GPP	O
Long	O
Term	O
Evolution	O
(	O
LTE	O
)	O
technology	O
is	O
often	O
branded	O
"	O
4G	B-Architecture
–	O
LTE	O
"	O
,	O
but	O
the	O
first	O
LTE	O
release	O
does	O
not	O
fully	O
comply	O
with	O
the	O
IMT-Advanced	O
requirements	O
.	O
</s>
<s>
The	O
physical	O
radio	O
interface	O
was	O
at	O
an	O
early	O
stage	O
named	O
High	O
Speed	O
OFDM	B-Protocol
Packet	O
Access	O
(	O
HSOPA	O
)	O
,	O
now	O
named	O
Evolved	O
UMTS	B-Protocol
Terrestrial	O
Radio	O
Access	O
(	O
E-UTRA	O
)	O
.	O
</s>
<s>
The	O
world	O
's	O
first	O
publicly	O
available	O
LTE	O
service	O
was	O
opened	O
in	O
the	O
two	O
Scandinavian	O
capitals	O
,	O
Stockholm	O
(	O
Ericsson	O
and	O
Nokia	O
Siemens	O
Networks	O
systems	O
)	O
and	O
Oslo	O
(	O
a	O
Huawei	O
system	O
)	O
on	O
December	O
14	O
,	O
2009	O
,	O
and	O
branded	O
4G	B-Architecture
.	O
</s>
<s>
The	O
user	O
terminals	O
were	O
manufactured	O
by	O
Samsung	B-Application
.	O
</s>
<s>
As	O
of	O
November	O
2012	O
,	O
the	O
five	O
publicly	O
available	O
LTE	O
services	O
in	O
the	O
United	O
States	O
are	O
provided	O
by	O
MetroPCS	O
,	O
Verizon	B-Application
Wireless	I-Application
,	O
AT&T	O
Mobility	O
,	O
U.S.	O
Cellular	O
,	O
Sprint	O
,	O
and	O
T-Mobile	O
US	O
.	O
</s>
<s>
T-Mobile	O
Hungary	O
launched	O
a	O
public	O
beta	O
test	O
(	O
called	O
friendly	O
user	O
test	O
)	O
on	O
7	O
October	O
2011	O
,	O
and	O
has	O
offered	O
commercial	O
4G	B-Architecture
LTE	O
services	O
since	O
1	O
January	O
2012	O
.	O
</s>
<s>
The	O
Mobile	O
WiMAX	O
(	O
IEEE	O
802.16e-2005	O
)	O
mobile	O
wireless	O
broadband	B-General_Concept
access	O
(	O
MWBA	O
)	O
standard	O
(	O
also	O
known	O
as	O
WiBro	O
in	O
South	O
Korea	O
)	O
is	O
sometimes	O
branded	O
4G	B-Architecture
,	O
and	O
offers	O
peak	O
data	O
rates	O
of	O
128Mbit/s	O
downlink	O
and	O
56Mbit/s	O
uplink	O
over	O
20MHz	O
wide	O
channels	O
.	O
</s>
<s>
Sprint	O
has	O
begun	O
using	O
Mobile	O
WiMAX	O
,	O
as	O
of	O
29	O
September	O
2008	O
,	O
branding	O
it	O
as	O
a	O
"	O
4G	B-Architecture
"	O
network	O
even	O
though	O
the	O
current	O
version	O
does	O
not	O
fulfill	O
the	O
IMT	O
Advanced	O
requirements	O
on	O
4G	B-Architecture
systems	O
.	O
</s>
<s>
In	O
Russia	O
,	O
Belarus	O
and	O
Nicaragua	O
WiMax	O
broadband	B-General_Concept
internet	O
access	O
were	O
offered	O
by	O
a	O
Russian	O
company	O
Scartel	O
,	O
and	O
was	O
also	O
branded	O
4G	B-Architecture
,	O
Yota	O
.	O
</s>
<s>
Just	O
as	O
Long-Term	O
Evolution	O
(	O
LTE	O
)	O
and	O
WiMAX	O
are	O
being	O
vigorously	O
promoted	O
in	O
the	O
global	O
telecommunications	O
industry	O
,	O
the	O
former	O
(	O
LTE	O
)	O
is	O
also	O
the	O
most	O
powerful	O
4G	B-Architecture
mobile	I-Architecture
communications	O
leading	O
technology	O
and	O
has	O
quickly	O
occupied	O
the	O
Chinese	O
market	O
.	O
</s>
<s>
TD-LTE	O
is	O
not	O
the	O
first	O
4G	B-Architecture
wireless	I-Architecture
mobile	O
broadband	B-General_Concept
network	O
data	O
standard	O
,	O
but	O
it	O
is	O
China	O
's	O
4G	B-Architecture
standard	O
that	O
was	O
amended	O
and	O
published	O
by	O
China	O
's	O
largest	O
telecom	O
operator	O
–	O
China	O
Mobile	O
.	O
</s>
<s>
UMB	O
(	O
Ultra	O
Mobile	O
Broadband	B-General_Concept
)	O
was	O
the	O
brand	O
name	O
for	O
a	O
discontinued	O
4G	B-Architecture
project	O
within	O
the	O
3GPP2	O
standardization	O
group	O
to	O
improve	O
the	O
CDMA2000	O
mobile	O
phone	O
standard	O
for	O
next	O
generation	O
applications	O
and	O
requirements	O
.	O
</s>
<s>
At	O
an	O
early	O
stage	O
the	O
Flash-OFDM	O
system	O
was	O
expected	O
to	O
be	O
further	O
developed	O
into	O
a	O
4G	B-Architecture
standard	O
.	O
</s>
<s>
The	O
iBurst	O
system	O
(	O
or	O
HC-SDMA	O
,	O
High	O
Capacity	O
Spatial	O
Division	O
Multiple	O
Access	O
)	O
was	O
at	O
an	O
early	O
stage	O
considered	O
to	O
be	O
a	O
4G	B-Architecture
predecessor	O
.	O
</s>
<s>
It	O
was	O
later	O
further	O
developed	O
into	O
the	O
Mobile	O
Broadband	B-General_Concept
Wireless	O
Access	O
(	O
MBWA	O
)	O
system	O
,	O
also	O
known	O
as	O
IEEE	O
802.20	O
.	O
</s>
<s>
The	O
following	O
key	O
features	O
can	O
be	O
observed	O
in	O
all	O
suggested	O
4G	B-Architecture
technologies	O
:	O
</s>
<s>
As	O
opposed	O
to	O
earlier	O
generations	O
,	O
4G	B-Architecture
systems	O
do	O
not	O
support	O
circuit	B-Protocol
switched	I-Protocol
telephony	O
.	O
</s>
<s>
IEEE	O
802.20	O
,	O
UMB	O
and	O
OFDM	B-Protocol
standards	O
lack	O
soft-handover	O
support	O
,	O
also	O
known	O
as	O
cooperative	O
relaying	O
.	O
</s>
<s>
In	O
addition	O
to	O
improvements	O
in	O
these	O
multiplexing	O
systems	O
,	O
improved	O
modulation	B-Application
techniques	O
are	O
being	O
used	O
.	O
</s>
<s>
Whereas	O
earlier	O
standards	O
largely	O
used	O
Phase-shift	B-General_Concept
keying	I-General_Concept
,	O
more	O
efficient	O
systems	O
such	O
as	O
64QAM	B-Device
are	O
being	O
proposed	O
for	O
use	O
with	O
the	O
3GPP	O
Long	O
Term	O
Evolution	O
standards	O
.	O
</s>
<s>
Unlike	O
3G	B-Architecture
,	O
which	O
is	O
based	O
on	O
two	O
parallel	O
infrastructures	O
consisting	O
of	O
circuit	B-Protocol
switched	I-Protocol
and	O
packet	B-Protocol
switched	I-Protocol
network	I-Protocol
nodes	O
,	O
4G	B-Architecture
is	O
based	O
on	O
packet	B-Protocol
switching	I-Protocol
only	O
.	O
</s>
<s>
As	O
IPv4	O
addresses	O
are	O
(	O
nearly	O
)	O
exhausted	B-Protocol
,	O
IPv6	B-Protocol
is	O
essential	O
to	O
support	O
the	O
large	O
number	O
of	O
wireless-enabled	O
devices	O
that	O
communicate	O
using	O
IP	O
.	O
</s>
<s>
By	O
increasing	O
the	O
number	O
of	O
IP	B-Protocol
addresses	I-Protocol
available	O
,	O
IPv6	B-Protocol
removes	O
the	O
need	O
for	O
network	B-Protocol
address	I-Protocol
translation	I-Protocol
(	O
NAT	O
)	O
,	O
a	O
method	O
of	O
sharing	O
a	O
limited	O
number	O
of	O
addresses	O
among	O
a	O
larger	O
group	O
of	O
devices	O
,	O
which	O
has	O
a	O
number	O
of	O
problems	O
and	O
limitations	O
.	O
</s>
<s>
When	O
using	O
IPv6	B-Protocol
,	O
some	O
kind	O
of	O
NAT	O
is	O
still	O
required	O
for	O
communication	O
with	O
legacy	O
IPv4	O
devices	O
that	O
are	O
not	O
also	O
IPv6-connected	O
.	O
</s>
<s>
,	O
Verizon	B-Application
has	O
posted	O
Specifications	O
that	O
require	O
any	O
4G	B-Architecture
devices	O
on	O
its	O
network	O
to	O
support	O
IPv6	B-Protocol
.	O
</s>
<s>
Recently	O
,	O
multiple	O
antenna	O
technologies	O
are	O
emerging	O
to	O
achieve	O
the	O
goal	O
of	O
4G	B-Architecture
systems	O
such	O
as	O
high	O
rate	O
,	O
high	O
reliability	O
,	O
and	O
long	O
range	O
communications	O
.	O
</s>
<s>
One	O
of	O
the	O
key	O
technologies	O
for	O
4G	B-Architecture
and	O
beyond	O
is	O
called	O
Open	O
Wireless	O
Architecture	O
(	O
OWA	O
)	O
,	O
supporting	O
multiple	O
wireless	O
air	O
interfaces	O
in	O
an	O
open	B-Architecture
architecture	I-Architecture
platform	O
.	O
</s>
<s>
SDR	B-Architecture
is	O
one	O
form	O
of	O
open	O
wireless	O
architecture	O
(	O
OWA	O
)	O
.	O
</s>
<s>
Since	O
4G	B-Architecture
is	O
a	O
collection	O
of	O
wireless	O
standards	O
,	O
the	O
final	O
form	O
of	O
a	O
4G	B-Architecture
device	O
will	O
constitute	O
various	O
standards	O
.	O
</s>
<s>
This	O
can	O
be	O
efficiently	O
realized	O
using	O
SDR	B-Architecture
technology	O
,	O
which	O
is	O
categorized	O
to	O
the	O
area	O
of	O
the	O
radio	O
convergence	O
.	O
</s>
<s>
The	O
4G	B-Architecture
system	O
was	O
originally	O
envisioned	O
by	O
the	O
DARPA	O
,	O
the	O
US	O
Defense	O
Advanced	O
Research	O
Projects	O
Agency	O
.	O
</s>
<s>
DARPA	O
selected	O
the	O
distributed	O
architecture	O
and	O
end-to-end	O
Internet	B-Protocol
protocol	I-Protocol
(	O
IP	O
)	O
,	O
and	O
believed	O
at	O
an	O
early	O
stage	O
in	O
peer-to-peer	O
networking	O
in	O
which	O
every	O
mobile	O
device	O
would	O
be	O
both	O
a	O
transceiver	O
and	O
a	O
router	O
for	O
other	O
devices	O
in	O
the	O
network	O
,	O
eliminating	O
the	O
spoke-and-hub	O
weakness	O
of	O
2G	O
and	O
3G	B-Architecture
cellular	I-Architecture
systems	O
.	O
</s>
<s>
Since	O
the	O
2.5G	O
GPRS	O
system	O
,	O
cellular	O
systems	O
have	O
provided	O
dual	O
infrastructures	O
:	O
packet	B-Protocol
switched	I-Protocol
nodes	O
for	O
data	O
services	O
,	O
and	O
circuit	B-Protocol
switched	I-Protocol
nodes	O
for	O
voice	O
calls	O
.	O
</s>
<s>
In	O
4G	B-Architecture
systems	O
,	O
the	O
circuit-switched	B-Protocol
infrastructure	O
is	O
abandoned	O
and	O
only	O
a	O
packet-switched	B-Protocol
network	I-Protocol
is	O
provided	O
,	O
while	O
2.5G	O
and	O
3G	B-Architecture
systems	O
require	O
both	O
packet-switched	B-Protocol
and	O
circuit-switched	B-Protocol
network	I-Protocol
nodes	O
,	O
i.e.	O
</s>
<s>
This	O
means	O
that	O
in	O
4G	B-Architecture
traditional	O
voice	O
calls	O
are	O
replaced	O
by	O
IP	B-Application
telephony	I-Application
.	O
</s>
<s>
In	O
2002	O
,	O
the	O
strategic	O
vision	O
for	O
4G	B-Architecture
—	O
which	O
ITU	O
designated	O
as	O
IMT	O
Advanced	O
—	O
was	O
laid	O
out	O
.	O
</s>
<s>
On	O
7	O
May	O
2008	O
,	O
Sprint	O
,	O
Imagine	O
,	O
Google	B-Application
,	O
Intel	O
,	O
Comcast	O
,	O
Bright	O
House	O
,	O
and	O
Time	O
Warner	O
announced	O
a	O
pooling	O
of	O
an	O
average	O
of	O
120MHz	O
of	O
spectrum	O
;	O
Sprint	O
merged	O
its	O
Xohm	O
WiMAX	O
division	O
with	O
Clearwire	O
to	O
form	O
a	O
company	O
which	O
will	O
take	O
the	O
name	O
"	O
Clear	O
"	O
.	O
</s>
<s>
In	O
February	O
2007	O
,	O
the	O
Japanese	O
company	O
NTT	O
DoCoMo	O
tested	O
a	O
4G	B-Architecture
communication	O
system	O
prototype	O
with	O
4×4	O
MIMO	O
called	O
VSF-OFCDM	O
at	O
100	O
Mbit/s	O
while	O
moving	O
,	O
and	O
1	O
Gbit/s	O
while	O
stationary	O
.	O
</s>
<s>
In	O
January	O
2008	O
,	O
a	O
U.S.	O
Federal	O
Communications	O
Commission	O
(	O
FCC	O
)	O
spectrum	B-Algorithm
auction	I-Algorithm
for	O
the	O
700MHz	O
former	O
analog	O
TV	O
frequencies	O
began	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
biggest	O
share	O
of	O
the	O
spectrum	O
went	O
to	O
Verizon	B-Application
Wireless	I-Application
and	O
the	O
next	O
biggest	O
to	O
AT&T	O
.	O
</s>
<s>
On	O
15	O
December	O
2008	O
,	O
San	O
Miguel	O
Corporation	O
,	O
the	O
largest	O
food	O
and	O
beverage	O
conglomerate	O
in	O
southeast	O
Asia	O
,	O
has	O
signed	O
a	O
memorandum	O
of	O
understanding	O
with	O
Qatar	O
Telecom	O
QSC	O
(	O
Qtel	O
)	O
to	O
build	O
wireless	O
broadband	B-General_Concept
and	O
mobile	O
communications	O
projects	O
in	O
the	O
Philippines	O
.	O
</s>
<s>
The	O
joint-venture	O
formed	O
wi-tribe	O
Philippines	O
,	O
which	O
offers	O
4G	B-Architecture
in	O
the	O
country	O
.	O
</s>
<s>
On	O
3	O
March	O
2009	O
,	O
Lithuania	O
's	O
LRTC	O
announcing	O
the	O
first	O
operational	O
"	O
4G	B-Architecture
"	O
mobile	O
WiMAX	O
network	O
in	O
Baltic	O
states	O
.	O
</s>
<s>
In	O
December	O
2009	O
,	O
Sprint	O
began	O
advertising	O
"	O
4G	B-Architecture
"	O
service	O
in	O
selected	O
cities	O
in	O
the	O
United	O
States	O
,	O
despite	O
average	O
download	O
speeds	O
of	O
only	O
3	O
–	O
6Mbit/s	O
with	O
peak	O
speeds	O
of	O
10Mbit/s	O
(	O
not	O
available	O
in	O
all	O
markets	O
)	O
.	O
</s>
<s>
TeliaSonera	O
branded	O
the	O
network	O
"	O
4G	B-Architecture
"	O
.	O
</s>
<s>
The	O
modem	O
devices	O
on	O
offer	O
were	O
manufactured	O
by	O
Samsung	B-Application
(	O
dongle	O
GT-B3710	O
)	O
,	O
and	O
the	O
network	O
infrastructure	O
created	O
by	O
Huawei	O
(	O
in	O
Oslo	O
)	O
and	O
Ericsson	O
(	O
in	O
Stockholm	O
)	O
.	O
</s>
<s>
Introductory	O
tests	O
showed	O
a	O
TCP	B-Protocol
throughput	O
of	O
42.8Mbit/s	O
downlink	O
and	O
5.3Mbit/s	O
uplink	O
in	O
Stockholm	O
.	O
</s>
<s>
On	O
4	O
June	O
2010	O
,	O
Sprint	O
released	O
the	O
first	O
WiMAX	O
smartphone	O
in	O
the	O
US	O
,	O
the	O
HTC	B-Application
Evo	I-Application
4G	I-Application
.	O
</s>
<s>
On	O
6	O
December	O
2010	O
,	O
at	O
the	O
ITU	O
World	O
Radiocommunication	O
Seminar	O
2010	O
,	O
the	O
ITU	O
stated	O
that	O
LTE	O
,	O
WiMAX	O
and	O
similar	O
"	O
evolved	O
3G	B-Architecture
technologies	O
"	O
could	O
be	O
considered	O
"	O
4G	B-Architecture
"	O
.	O
</s>
<s>
In	O
2011	O
,	O
Argentina	O
's	O
Claro	O
launched	O
a	O
pre-4G	O
HSPA+	O
network	O
in	O
the	O
country	O
.	O
</s>
<s>
In	O
2011	O
,	O
Thailand	O
's	O
Truemove-H	O
launched	O
a	O
pre-4G	O
HSPA+	O
network	O
with	O
nationwide	O
availability	O
.	O
</s>
<s>
On	O
March	O
17	O
,	O
2011	O
,	O
the	O
HTC	B-Application
Thunderbolt	I-Application
offered	O
by	O
Verizon	B-Application
in	O
the	O
U.S.	O
was	O
the	O
second	O
LTE	O
smartphone	O
to	O
be	O
sold	O
commercially	O
.	O
</s>
<s>
4G	B-Architecture
introduces	O
a	O
potential	O
inconvenience	O
for	O
those	O
who	O
travel	O
internationally	O
or	O
wish	O
to	O
switch	O
carriers	O
.	O
</s>
<s>
In	O
order	O
to	O
make	O
and	O
receive	O
4G	B-Architecture
voice	O
calls	O
(	O
VoLTE	O
)	O
,	O
the	O
subscriber	O
handset	O
must	O
not	O
only	O
have	O
a	O
matching	O
frequency	B-Algorithm
band	I-Algorithm
(	O
and	O
in	O
some	O
cases	O
require	O
unlocking	O
)	O
,	O
it	O
must	O
also	O
have	O
the	O
matching	O
enablement	O
settings	O
for	O
the	O
local	O
carrier	O
and/or	O
country	O
.	O
</s>
<s>
While	O
a	O
phone	O
purchased	O
from	O
a	O
given	O
carrier	O
can	O
be	O
expected	O
to	O
work	O
with	O
that	O
carrier	O
,	O
making	O
4G	B-Architecture
voice	O
calls	O
on	O
another	O
carrier	O
's	O
network	O
(	O
including	O
international	O
roaming	O
)	O
may	O
be	O
impossible	O
without	O
a	O
software	O
update	O
specific	O
to	O
the	O
local	O
carrier	O
and	O
the	O
phone	O
model	O
in	O
question	O
,	O
which	O
may	O
or	O
may	O
not	O
be	O
available	O
(	O
although	O
fallback	O
to	O
2G/3G	O
for	O
voice	O
calling	O
may	O
still	O
be	O
possible	O
if	O
a	O
2G/3G	O
network	O
is	O
available	O
with	O
a	O
matching	O
frequency	B-Algorithm
band	I-Algorithm
)	O
.	O
</s>
<s>
A	O
major	O
issue	O
in	O
4G	B-Architecture
systems	O
is	O
to	O
make	O
the	O
high	O
bit	O
rates	O
available	O
in	O
a	O
larger	O
portion	O
of	O
the	O
cell	O
,	O
especially	O
to	O
users	O
in	O
an	O
exposed	O
position	O
in	O
between	O
several	O
base	O
stations	O
.	O
</s>
<s>
In	O
current	O
research	O
,	O
this	O
issue	O
is	O
addressed	O
by	O
macro-diversity	B-Protocol
techniques	O
,	O
also	O
known	O
as	O
group	B-Protocol
cooperative	I-Protocol
relay	I-Protocol
,	O
and	O
also	O
by	O
Beam-Division	O
Multiple	O
Access	O
(	O
BDMA	O
)	O
.	O
</s>
<s>
Pervasive	B-Architecture
networks	I-Architecture
are	O
an	O
amorphous	O
and	O
at	O
present	O
entirely	O
hypothetical	O
concept	O
where	O
the	O
user	O
can	O
be	O
simultaneously	O
connected	O
to	O
several	O
wireless	O
access	O
technologies	O
and	O
can	O
seamlessly	O
move	O
between	O
them	O
(	O
See	O
vertical	B-General_Concept
handoff	I-General_Concept
,	O
IEEE	O
802.21	O
)	O
.	O
</s>
<s>
These	O
access	O
technologies	O
can	O
be	O
Wi-Fi	O
,	O
UMTS	B-Protocol
,	O
EDGE	O
,	O
or	O
any	O
other	O
future	O
access	O
technology	O
.	O
</s>
<s>
Included	O
in	O
this	O
concept	O
is	O
also	O
smart-radio	O
(	O
also	O
known	O
as	O
cognitive	B-Protocol
radio	I-Protocol
)	O
technology	O
to	O
efficiently	O
manage	O
spectrum	O
use	O
and	O
transmission	O
power	O
as	O
well	O
as	O
the	O
use	O
of	O
mesh	B-Architecture
routing	I-Architecture
protocols	O
to	O
create	O
a	O
pervasive	B-Architecture
network	I-Architecture
.	O
</s>
