/

.

:

1.

2.

3. OFDM SISO MIMO

4.

1.

3

(Underwater

Acoustic Communications UAC)

, ,

UAC

,

(Underwater Acoustics)

1.

4

(1/2)

1490 Leonardo da Vinci :

,

.

1687 Isaac Newton

,

1826 ,

Daniel Colladon Charles Sturm.

1435 m/sec 2%

1877

Rayleigh

To 1912

1.

5

(2/2)

echoranger 1914

Reginald Aubrey Fessenden

1919

1920 1930 ,

Sonar

(antisubmarine vessels)

1946

, Sonar

,

.

2.

6

(1/2)

:

(transmission distance)

(multipath propagation)

(surface

and bottom reflections)

(bandwidth)

(attenuation)

(absorption)

(c 1500 m/sec)

2.

7

(2/2)

(path loss) :

(spreading loss)

Thorp

2.

8

(1/2)

:

o

( -1)

path loss

(delay) ( = / )

2.

9

(2/2)

2.

10

2.

11

(1/2)

(Scattering), ,

,

, ,

Rayleigh Rice

Jakes,

:

Bessel

2.

12

(2/2)

MIMO

MIMO

(Distributed MIMO)

2.

13

:

(Site

specific Noise)

(Ambient Noise)

(Site

specific Noise),

:

,

Gaussian

2.

14

(1/3)

(Ambient Noise),

:

(turbulence) / (microseisms)

(distant shipping activity)

(breaking waves wind

speed)

(thermal

noise)

Gaussian ,

2.

15

(2/3)

:

2.

16

(3/3)

3. OFDM SISO MIMO

17

(Orthogonal Frequency Division Multiplexing)

(Modulation)

,

OFDM (InterSymbol

Interference ISI)

OFDM ,

3. OFDM SISO MIMO

18

(1/4)

OFDM :

Fourier

(cyclic prefix)

OFDM :

Fourier

3. OFDM SISO MIMO

19

(2/4)

OFDM :

Fourier :

:

OFDM :

3. OFDM SISO MIMO

20

(3/4)

:

OFDM :

:

3. OFDM SISO MIMO

21

(4/4)

,

EVD (EigenValue Decomposition) :

:

:

3. OFDM SISO MIMO

22

SISO OFDM

: OFDM

:

3. OFDM SISO MIMO

23

MIMO OFDM (1/4)

(Beamforming) :

- (transmit precoding)

(receiver shaping)

(Maximal Ratio Combining Diversity

MRC)

3. OFDM SISO MIMO

24

MIMO OFDM (2/4)

MIMO :

OFDM

3. OFDM SISO MIMO

25

MIMO OFDM (3/4)

(Beamformong) :

(Singular Value Decomposition

SVD) :

:

:

3. OFDM SISO MIMO

26

MIMO OFDM (4/4)

(Maximal Ratio Combining Diversity

MRC) :

:

:

, ,

4.

27

:

4.

28

SISO OFDM

5 km

50

4.

29

MIMO OFDM

20 km

50

!