MB-OFDM transmitter and receiver and signal processing method thereof
View Patent ↗A method of improving frequency diversity of a signal that includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols comprises receiving an input data sequence, mapping the input data sequence to a transmission data sequence, wherein the mapping includes performing a mapping operation and generating an OFDM symbol using the transmission data sequence. An orthogonal frequency division multiplexing (OFDM) transmitter comprises an interface configured to receive an input data sequence, and a processor configured to perform a mapping operation, to map the input data sequence to a transmission data sequence wherein the mapping includes performing the mapping operation, and to generate an OFDM symbol using the transmission data sequence.
1. An OFDM (Orthogonal Frequency Division Multiplexing) transmitting apparatus, comprising:
an interface which receives an input data sequence; and
a processor connected with the interface, and maps the input data sequence into a transmission data sequence, and generates an OFDM symbol by using the transmission data sequence, wherein:
the mapping comprises at least one of repetition, shift, reversal, shift-plus-reversal, and reversal-plus-shift;
the shift comprises a circulative shift; and
the circulative shift is performed with respect to the input data sequence a T [i] according to the equation:
b[i]=a T [m ( i ) SN CBPS +mod( i+m ( i ) SN cyc ,N CBPS )], where m ( i )=* i/N CBPS +, i= 0 , . . . , N CBP6S −1,
N CBPS is a number of coded bits per OFDM symbol, N cyc is a number of circulative shifts, and N CBP6S is a number of coded bits per 6 OFDM symbols.
2. An OFDM (Orthogonal Frequency Division Multiplexing) transmitting apparatus, comprising:
an interface which receives an input data sequence; and
a processor connected with the interface, interleaves the input data sequence, shifts the input data sequence and generates the shifted input data sequence, generates an OFDM symbol by applying an IFFT(Inverse Fast Fourier Transform) with respect to the shifted input data sequence, exchanges an I and a Q components of a part of the OFDM symbol, generates an RF signal by modulating the exchanged OFDM symbol, and transmits the RF signal, wherein the processor exchanges the I and Q components according to the following equations with respect to the OFDM symbol with d frame [k], k=0,1,2, . . . :
C
D
,
2
n
[
l
]
=
d
frame
[
N
D
2
s
(
2
n
-
N
sync
-
N
hdr
)
+
l
]
C
D
,
2
n
+
1
=
Pspread
[
n
]
s
{
imag
(
d
frame
[
N
D
2
s
(
2
n
-
N
sync
-
N
hdr
)
+
(
N
D
-
1
-
l
]
}
+
j
real
(
d
frame
[
N
D
2
s
(
2
n
-
N
sync
-
N
hdr
)
+
(
N
D
-
1
-
l
]
)
Where, C D,2n [I] denotes the first OFDM symbol, C D,2n+1 [I] denotes the second OFDM symbol, N D denotes a constant value for grouping the OFDM symbols, N D is a number of data subcarriers, N sync is a number of symbols of a PLCP preamble, and N hdr is a number of symbols of a PLCP header.
3. The OFDM transmitting apparatus of claim 2 , wherein the Pspread is calculated by the following equation:
Pspread
[
n
]
=
p
[
mod
(
n
-
N
sync
2
+
6
,
N
FFT
-
1
)
]
where N FFT is a number of points in a Fast Fourier Transform (FFT) and p[.] denotes a pseudo random sequence of a predetermined length.