<s>
In	O
a	O
hierarchical	O
telecommunications	O
network	O
,	O
the	O
backhaul	B-General_Concept
portion	O
of	O
the	O
network	O
comprises	O
the	O
intermediate	O
links	O
between	O
the	O
core	B-General_Concept
network	I-General_Concept
,	O
or	O
backbone	B-General_Concept
network	I-General_Concept
,	O
and	O
the	O
small	O
subnetworks	O
at	O
the	O
edge	B-Device
of	O
the	O
network	O
.	O
</s>
<s>
The	O
most	O
common	O
network	O
type	O
in	O
which	O
backhaul	B-General_Concept
is	O
implemented	O
is	O
a	O
mobile	O
network	O
.	O
</s>
<s>
A	O
backhaul	B-General_Concept
of	O
a	O
mobile	O
network	O
,	O
also	O
referred	O
to	O
as	O
mobile-backhaul	O
connects	O
a	O
cell	O
site	O
towards	O
the	O
core	B-General_Concept
network	I-General_Concept
.	O
</s>
<s>
The	O
two	O
main	O
methods	O
of	O
mobile	O
backhaul	B-General_Concept
implementations	O
are	O
fiber-based	O
backhaul	B-General_Concept
and	O
wireless	O
point-to-point	B-Architecture
backhaul	B-General_Concept
.	O
</s>
<s>
Other	O
methods	O
,	O
such	O
as	O
copper-based	O
wireline	O
,	O
satellite	O
communications	O
and	O
point-to-multipoint	B-General_Concept
wireless	O
technologies	O
are	O
being	O
phased	O
out	O
as	O
capacity	O
and	O
latency	O
requirements	O
become	O
higher	O
in	O
4G	O
and	O
5G	O
networks	O
.	O
</s>
<s>
In	O
both	O
the	O
technical	O
and	O
commercial	O
definitions	O
,	O
backhaul	B-General_Concept
generally	O
refers	O
to	O
the	O
side	O
of	O
the	O
network	O
that	O
communicates	O
with	O
the	O
global	O
Internet	O
,	O
paid	O
for	O
at	O
wholesale	O
commercial	O
access	O
rates	O
to	O
or	O
at	O
an	O
Internet	B-Protocol
exchange	I-Protocol
point	I-Protocol
or	O
other	O
core	B-General_Concept
network	I-General_Concept
access	O
location	O
.	O
</s>
<s>
Sometimes	O
middle	B-Architecture
mile	I-Architecture
networks	O
exist	O
between	O
the	O
customer	O
's	O
own	O
LAN	B-General_Concept
and	O
those	O
exchanges	O
.	O
</s>
<s>
Cell	O
phones	O
communicating	O
with	O
a	O
single	O
cell	O
tower	O
constitute	O
a	O
local	O
subnetwork	O
;	O
the	O
connection	O
between	O
the	O
cell	O
tower	O
and	O
the	O
rest	O
of	O
the	O
world	O
begins	O
with	O
a	O
backhaul	B-General_Concept
link	O
to	O
the	O
core	O
of	O
the	O
internet	O
service	O
provider	O
's	O
network	O
(	O
via	O
a	O
point	O
of	O
presence	O
)	O
.	O
</s>
<s>
A	O
backhaul	B-General_Concept
may	O
include	O
wired	O
,	O
fiber	B-Architecture
optic	I-Architecture
and	O
wireless	O
components	O
.	O
</s>
<s>
Wireless	O
sections	O
may	O
include	O
using	O
microwave	O
bands	O
and	O
mesh	B-Architecture
and	O
edge	B-Device
network	O
topologies	O
that	O
may	O
use	O
a	O
high-capacity	O
wireless	O
channel	O
to	O
get	O
packets	O
to	O
the	O
microwave	O
or	O
fiber	O
links	O
.	O
</s>
<s>
Visualizing	O
the	O
entire	O
hierarchical	O
network	O
as	O
a	O
human	O
skeleton	O
,	O
the	O
core	B-General_Concept
network	I-General_Concept
would	O
represent	O
the	O
spine	O
,	O
the	O
backhaul	B-General_Concept
links	O
would	O
be	O
the	O
limbs	O
,	O
the	O
edge	B-Device
networks	O
would	O
be	O
the	O
hands	O
and	O
feet	O
,	O
and	O
the	O
individual	O
links	O
within	O
those	O
edge	B-Device
networks	O
would	O
be	O
the	O
fingers	O
and	O
toes	O
.	O
</s>
<s>
Connecting	O
DSLAMs	B-Protocol
to	O
the	O
nearest	O
ATM	O
or	O
Ethernet	O
aggregation	O
node	O
.	O
</s>
<s>
Connecting	O
a	O
large	O
company	O
's	O
site	O
to	O
a	O
metro	B-Protocol
Ethernet	I-Protocol
network	O
.	O
</s>
<s>
A	O
telephone	O
company	O
is	O
very	O
often	O
the	O
internet	O
service	O
provider	O
providing	O
backhaul	B-General_Concept
,	O
although	O
for	O
academic	O
research	O
and	O
education	O
networks	O
,	O
large	O
commercial	O
networks	O
or	O
municipal	O
networks	O
,	O
it	O
is	O
increasingly	O
common	O
to	O
connect	O
to	O
public	O
broadband	O
backhaul	B-General_Concept
.	O
</s>
<s>
The	O
US	O
plan	O
for	O
instance	O
,	O
specifies	O
that	O
all	O
community	O
anchor	O
institutions	O
should	O
be	O
connected	O
by	O
gigabit	O
fiber	B-Architecture
optics	I-Architecture
before	O
the	O
end	O
of	O
2020	O
.	O
</s>
<s>
The	O
choice	O
of	O
backhaul	B-General_Concept
technology	O
must	O
take	O
account	O
of	O
such	O
parameters	O
as	O
capacity	O
,	O
cost	O
,	O
reach	O
,	O
and	O
the	O
need	O
for	O
such	O
resources	O
as	O
frequency	O
spectrum	O
,	O
optical	B-Architecture
fiber	I-Architecture
,	O
wiring	O
,	O
or	O
rights	O
of	O
way	O
.	O
</s>
<s>
Generally	O
,	O
backhaul	B-General_Concept
solutions	O
can	O
largely	O
be	O
categorized	O
into	O
wired	O
(	O
leased	B-Architecture
lines	I-Architecture
or	O
copper/fiber	O
)	O
or	O
wireless	O
(	O
point-to-point	B-Architecture
,	O
point-to-multipoint	B-General_Concept
over	O
high-capacity	O
radio	O
links	O
)	O
.	O
</s>
<s>
Multi-hop	B-General_Concept
wireless	O
architecture	O
can	O
overcome	O
the	O
hurdles	O
of	O
wired	O
solutions	O
to	O
create	O
efficient	O
large	O
coverage	O
areas	O
and	O
with	O
growing	O
demand	O
in	O
emerging	O
markets	O
where	O
often	O
cost	O
is	O
a	O
major	O
factor	O
in	O
deciding	O
technologies	O
,	O
a	O
wireless	O
backhaul	B-General_Concept
solution	O
is	O
able	O
to	O
offer	O
'	O
carrier-grade	O
'	O
services	O
,	O
whereas	O
this	O
is	O
not	O
easily	O
feasible	O
with	O
wired	O
backhaul	B-General_Concept
connectivity	O
.	O
</s>
<s>
Backhaul	B-General_Concept
technologies	O
include	O
:	O
</s>
<s>
PDH	B-Protocol
and	O
SDH/SONET	B-Protocol
interfaces	O
,	O
such	O
as	O
(	O
fractional	O
)	O
E1/T1	O
,	O
E3	O
,	O
T3	O
,	O
STM-1/OC	O
-3	O
,	O
etc	O
.	O
</s>
<s>
Backhaul	B-General_Concept
capacity	O
can	O
also	O
be	O
leased	O
from	O
another	O
network	O
operator	O
,	O
in	O
which	O
case	O
that	O
other	O
network	O
operator	O
generally	O
selects	O
the	O
technology	O
being	O
used	O
,	O
though	O
this	O
can	O
be	O
limited	O
to	O
fewer	O
technologies	O
if	O
the	O
requirement	O
is	O
very	O
specific	O
such	O
as	O
short-term	O
links	O
for	O
emergency/disaster	O
relief	O
or	O
for	O
public	O
events	O
,	O
where	O
cost	O
and	O
time	O
would	O
be	O
major	O
factors	O
and	O
would	O
immediately	O
rule	O
out	O
wired	O
solutions	O
,	O
unless	O
pre-existing	O
infrastructure	O
was	O
readily	O
accessible	O
or	O
available	O
.	O
</s>
<s>
Wireless	O
backhaul	B-General_Concept
is	O
easy	O
to	O
deploy	O
,	O
cost	O
efficient	O
and	O
can	O
provide	O
high	O
capacity	O
connectivity	O
,	O
e.g.	O
,	O
multiple	O
gigabits	O
per	O
second	O
,	O
and	O
even	O
tens	O
of	O
Gbps	O
.	O
</s>
<s>
Wireline	O
fiber	O
backhaul	B-General_Concept
,	O
on	O
the	O
other	O
hand	O
,	O
can	O
provide	O
practically	O
endless	O
capacity	O
,	O
but	O
requires	O
investment	O
in	O
deploying	O
fiber	O
as	O
well	O
as	O
in	O
optical	O
equipment	O
.	O
</s>
<s>
The	O
type	O
of	O
backhaul	B-General_Concept
for	O
each	O
site	O
is	O
determined	O
taking	O
into	O
consideration	O
the	O
capacity	O
requirement	O
(	O
current	O
and	O
future	O
)	O
,	O
deployment	O
timeline	O
,	O
fiber	O
availability	O
and	O
feasibility	O
and	O
budget	O
constraints	O
.	O
</s>
<s>
Mesh	B-Architecture
networks	I-Architecture
are	O
unique	O
enablers	O
that	O
can	O
reduce	O
this	O
cost	O
due	O
to	O
their	O
flexible	O
architecture	O
.	O
</s>
<s>
With	O
mesh	B-Architecture
networking	I-Architecture
,	O
access	O
points	O
are	O
connected	O
wirelessly	O
and	O
exchange	O
data	O
frames	O
with	O
each	O
other	O
to	O
forward	O
to/from	O
a	O
gateway	O
point	O
.	O
</s>
<s>
Since	O
a	O
mesh	B-Architecture
requires	O
no	O
costly	O
cable	O
constructions	O
for	O
its	O
backhaul	B-General_Concept
network	I-General_Concept
,	O
it	O
reduces	O
total	O
investment	O
cost	O
.	O
</s>
<s>
Mesh	B-Architecture
technology	O
’s	O
capabilities	O
can	O
boost	O
extending	O
coverage	O
of	O
service	O
areas	O
easily	O
and	O
flexibly	O
.	O
</s>
<s>
For	O
further	O
cost	O
reduction	O
,	O
a	O
large-scale	O
high-capacity	O
mesh	B-Architecture
is	O
desirable	O
.	O
</s>
<s>
For	O
instance	O
,	O
Kyushu	O
University	O
's	O
Mimo-Mesh	O
Project	O
,	O
based	O
in	O
Fukuoka	O
City	O
,	O
Fukuoka	O
Prefecture	O
,	O
Japan	O
,	O
has	O
developed	O
and	O
put	O
into	O
use	O
new	O
technology	O
for	O
building	O
high	O
capacity	O
mesh	B-Architecture
infrastructure	O
.	O
</s>
<s>
A	O
key	O
component	O
is	O
called	O
IPT	O
,	O
intermittent	O
periodic	O
transmit	O
,	O
a	O
proprietary	O
packet-forwarding	O
scheme	O
that	O
is	O
designed	O
to	O
reduce	O
radio	O
interference	O
in	O
the	O
forwarding	O
path	O
of	O
mesh	B-Architecture
networks	I-Architecture
.	O
</s>
<s>
In	O
2010	O
,	O
hundreds	O
of	O
wireless	B-Architecture
LAN	I-Architecture
access	O
points	O
incorporating	O
the	O
technology	O
were	O
installed	O
in	O
the	O
commercial	O
shopping	O
and	O
entertainment	O
complex	O
,	O
Canal	O
City	O
Hakata	O
,	O
resulting	O
in	O
the	O
successful	O
operation	O
of	O
one	O
of	O
the	O
world	O
's	O
largest	O
indoor	O
wireless	O
multi-hop	B-General_Concept
backhauls	B-General_Concept
.	O
</s>
<s>
That	O
network	O
uses	O
a	O
wireless	O
multi-hop	B-General_Concept
relay	O
of	O
up	O
to	O
11	O
access	O
points	O
while	O
delivering	O
high	O
bandwidth	O
to	O
end	O
users	O
.	O
</s>
<s>
Actual	O
throughput	O
is	O
double	O
that	O
of	O
standard	O
mesh	B-Architecture
network	I-Architecture
systems	O
using	O
conventional	O
packet	O
forwarding	O
.	O
</s>
<s>
Latency	O
,	O
as	O
in	O
all	O
multi-hop	B-General_Concept
relays	O
,	O
suffers	O
,	O
but	O
not	O
to	O
the	O
degree	O
that	O
it	O
compromises	O
voice	B-Application
over	I-Application
IP	I-Application
communications	O
.	O
</s>
<s>
Many	O
common	O
wireless	O
mesh	B-Architecture
network	I-Architecture
hotspot	B-Application
solutions	O
are	O
supported	O
in	O
open	B-License
source	I-License
router	O
firmware	O
including	O
DD-WRT	B-Protocol
,	O
OpenWRT	B-Application
and	O
derivatives	O
.	O
</s>
<s>
The	O
IEEE	O
802.21	O
standard	O
specifies	O
basic	O
capabilities	O
for	O
such	O
systems	O
including	O
802.11u	O
unknown	O
user	O
authentication	O
and	O
802.11s	O
ad	O
hoc	O
wireless	O
mesh	B-Architecture
networking	I-Architecture
support	O
.	O
</s>
<s>
Effectively	O
these	O
allow	O
arbitrary	O
wired	O
net	O
connections	O
to	O
be	O
teamed	O
or	O
ganged	O
into	O
what	O
appears	O
to	O
be	O
a	O
single	O
backhaul	B-General_Concept
–	O
a	O
"	O
virtual	B-General_Concept
private	I-General_Concept
cloud	I-General_Concept
"	O
.	O
</s>
<s>
The	O
use	O
of	O
the	O
term	O
backhaul	B-General_Concept
to	O
describe	O
this	O
type	O
of	O
connectivity	O
may	O
be	O
controversial	O
technically	O
.	O
</s>
<s>
Several	O
companies	O
,	O
including	O
Prysmian	O
,	O
run	O
both	O
HVDC	O
power	O
cables	O
and	O
telecommunications	O
cables	O
as	O
far	O
as	O
FTTx	B-Architecture
.	O
</s>
<s>
This	O
reflects	O
the	O
fact	O
that	O
telecommunications	O
backhaul	B-General_Concept
and	O
long	O
range	O
high	O
voltage	O
electricity	O
transmission	O
have	O
many	O
technologies	O
in	O
common	O
,	O
and	O
are	O
almost	O
identical	O
in	O
terms	O
of	O
route	O
clearing	O
,	O
liability	O
in	O
outages	O
,	O
and	O
other	O
legal	O
aspects	O
.	O
</s>
