<s>
Non-orthogonal	B-Architecture
frequency-division	I-Architecture
multiplexing	I-Architecture
(	O
N-OFDM	B-Architecture
)	O
is	O
a	O
method	O
of	O
encoding	O
digital	O
data	O
on	O
multiple	O
carrier	O
frequencies	O
with	O
non-orthogonal	O
intervals	O
between	O
frequency	O
of	O
sub-carriers	O
.	O
</s>
<s>
N-OFDM	B-Architecture
signals	O
can	O
be	O
used	O
in	O
communication	O
and	O
radar	B-Application
systems	I-Application
.	O
</s>
<s>
The	O
low-pass	B-Algorithm
equivalent	I-Algorithm
N-OFDM	B-Architecture
signal	O
is	O
expressed	O
as	O
:	O
</s>
<s>
where	O
are	O
the	O
data	O
symbols	O
,	O
is	O
the	O
number	O
of	O
sub-carriers	O
,	O
and	O
is	O
the	O
N-OFDM	B-Architecture
symbol	O
time	O
.	O
</s>
<s>
The	O
history	O
of	O
N-OFDM	B-Architecture
signals	O
theory	O
was	O
started	O
in	O
1992	O
from	O
the	O
Patent	O
of	O
Russian	O
Federation	O
No	O
.	O
</s>
<s>
In	O
this	O
patent	O
,	O
Vadym	O
Slyusar	O
proposed	O
the	O
1st	O
method	O
of	O
optimal	O
processing	O
for	O
N-OFDM	B-Architecture
signals	O
after	O
Fast	O
Fourier	O
transform	O
(	O
FFT	O
)	O
.	O
</s>
<s>
In	O
this	O
regard	O
need	O
to	O
say	O
that	O
W	O
.	O
Kozek	O
and	O
A	O
.	O
F	O
.	O
Molisch	O
wrote	O
in	O
1998	O
about	O
N-OFDM	B-Architecture
signals	O
with	O
that	O
"	O
it	O
is	O
not	O
possible	O
to	O
recover	O
the	O
information	O
from	O
the	O
received	O
signal	O
,	O
even	O
in	O
the	O
case	O
of	O
an	O
ideal	O
channel.	O
"	O
</s>
<s>
In	O
2001	O
,	O
V	O
.	O
Slyusar	O
proposed	O
non-orthogonal	O
frequency	O
digital	O
modulation	O
(	O
N-OFDM	B-Architecture
)	O
as	O
an	O
alternative	O
of	O
OFDM	B-Protocol
for	O
communications	O
systems	O
.	O
</s>
<s>
Despite	O
the	O
increased	O
complexity	O
of	O
demodulating	O
N-OFDM	B-Architecture
signals	O
compared	O
to	O
OFDM	B-Protocol
,	O
the	O
transition	O
to	O
non-orthogonal	O
subcarrier	O
frequency	O
arrangement	O
provides	O
several	O
advantages	O
:	O
</s>
<s>
This	O
section	O
describes	O
a	O
simple	O
idealized	O
N-OFDM	B-Architecture
system	O
model	O
suitable	O
for	O
a	O
time-invariant	O
AWGN	O
channel	O
.	O
</s>
<s>
An	O
N-OFDM	B-Architecture
carrier	O
signal	O
is	O
the	O
sum	O
of	O
a	O
number	O
of	O
not-orthogonal	O
subcarriers	O
,	O
with	O
baseband	B-Algorithm
data	O
on	O
each	O
subcarrier	O
being	O
independently	O
modulated	O
commonly	O
using	O
some	O
type	O
of	O
quadrature	B-Device
amplitude	I-Device
modulation	I-Device
(	O
QAM	B-Device
)	O
or	O
phase-shift	B-General_Concept
keying	I-General_Concept
(	O
PSK	B-General_Concept
)	O
.	O
</s>
<s>
This	O
composite	O
baseband	B-Algorithm
signal	I-Algorithm
is	O
typically	O
used	O
to	O
modulate	O
a	O
main	O
RF	O
carrier	O
.	O
</s>
<s>
By	O
inverse	B-Protocol
multiplexing	I-Protocol
,	O
these	O
are	O
first	O
demultiplexed	O
into	O
parallel	O
streams	O
,	O
and	O
each	O
one	O
mapped	O
to	O
a	O
(	O
possibly	O
complex	O
)	O
symbol	O
stream	O
using	O
some	O
modulation	O
constellation	O
(	O
QAM	B-Device
,	O
PSK	B-General_Concept
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
A	O
Digital	B-Architecture
Signal	I-Architecture
Processor	I-Architecture
(	O
DSP	O
)	O
is	O
computed	O
on	O
each	O
set	O
of	O
symbols	O
,	O
giving	O
a	O
set	O
of	O
complex	O
time-domain	O
samples	O
.	O
</s>
<s>
The	O
receiver	O
picks	O
up	O
the	O
signal	O
,	O
which	O
is	O
then	O
quadrature-mixed	O
down	O
to	O
baseband	B-Algorithm
using	O
cosine	O
and	O
sine	O
waves	O
at	O
the	O
carrier	O
frequency	O
.	O
</s>
<s>
The	O
baseband	B-Algorithm
signals	I-Algorithm
are	O
then	O
sampled	O
and	O
digitised	O
using	O
analog-to-digital	O
converters	O
(	O
ADCs	O
)	O
,	O
and	O
a	O
forward	O
FFT	O
is	O
used	O
to	O
convert	O
back	O
to	O
the	O
frequency	O
domain	O
.	O
</s>
<s>
This	O
returns	O
parallel	O
streams	O
,	O
which	O
use	O
in	O
appropriate	O
symbol	O
detector	B-Algorithm
.	O
</s>
<s>
The	O
1st	O
method	O
of	O
optimal	O
processing	O
for	O
N-OFDM	B-Architecture
signals	O
after	O
FFT	O
was	O
proposed	O
in	O
1992	O
.	O
</s>
<s>
The	O
method	O
of	O
optimal	O
processing	O
for	O
N-OFDM	B-Architecture
signals	O
without	O
FFT	O
was	O
proposed	O
in	O
October	O
2003	O
.	O
</s>
<s>
The	O
combination	O
N-OFDM	B-Architecture
and	O
MIMO	O
technology	O
is	O
similar	O
to	O
OFDM	B-Protocol
.	O
</s>
<s>
To	O
the	O
building	O
of	O
MIMO	O
system	O
can	O
be	O
used	O
digital	B-Algorithm
antenna	I-Algorithm
array	I-Algorithm
as	O
transmitter	O
and	O
receiver	O
of	O
N-OFDM	B-Architecture
signals	O
.	O
</s>
<s>
Fast-OFDM	O
method	O
was	O
proposed	O
in	O
2002	O
.	O
</s>
<s>
As	O
example	O
of	O
FBMC	O
can	O
consider	O
Wavelet	O
N-OFDM	B-Architecture
.	O
</s>
<s>
N-OFDM	B-Architecture
has	O
become	O
a	O
technique	O
for	O
power-line	B-Device
communications	I-Device
(	O
PLC	O
)	O
.	O
</s>
<s>
On	O
the	O
receiver	O
side	O
,	O
an	O
analysis	O
bank	O
is	O
used	O
to	O
demodulate	B-Device
the	O
signal	O
again	O
.	O
</s>
<s>
N-OFDM	B-Architecture
is	O
a	O
spectrally	O
efficient	O
method	O
.	O
</s>
<s>
All	O
SEFDM	O
methods	O
are	O
similar	O
to	O
N-OFDM	B-Architecture
.	O
</s>
