Telecom Trends1

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telecoms

: , , , , , , , , , UTP, , , TCP/IP, routers, switches, hubs, WiFi, WiMax, Ethernet, , , , , , , , ADSL, FTTH, OFDM,PAM, OOK, WDM, PCM, ,

:

. . , , 6 (2003).

Andrew S. Tanenbaum, Computer Networks, Prentice Hall (2003)

: http://galaxy.hua.gr/~thkam

Youtube channel: http://www.youtube.com/user/thomaskamalakis

video : http://galaxy.hua.gr/~thkam/telecomintrocourses_GR.html

: . , , .

( ).

: . 480Km .

( ) 150 .. .

, .

.

- 1792

1792 Claude Chappe .

Chappe 32 .

- 1837

To 1837 Wheatstone Cooke Morse ... .

1866

Charles Wheatstone William Fothergill CookeSamuel Morse

- 1876

To 1876 Bell Grey .

1878 1879 New Haven

Alexander Bell Elisha Grey

- 1906

H 1906 .

Lee De Forest

(grid) / Vg / Va

1915

- 1897

1897, Almond Strowger .

AM - 1920

AM 1920 ... Pittsburg KDKA

To 1918 o dwin Armstrong . FM 1933.

Edwin Armstong

To - 1929

o 1929 o V.K. Zworykin ...

1936 BBC . .

V.K. ZworykinC broadcasting house

To - 1947

1947 Brattain, Bardeen Shockley

.

- 1958

1958 Jack Kilby Robert Noyce .

LASER - 1962

1962 Robert Hall LASER.

LASER

- 1962

To 1962 Telstar I TV .

1965 Early Bird, .

Telstar I Early Bird

( 75-100 ).

( )

: 2

5

Internet - 1969

Internet Protocol (IP) DARPA 70.

1969 ARPANET

1975, TCP/IP Stanford University College London (UCL).

DSL - 1988

To DSL Bellcore ( Telecordia Technologies) 1988

24Mb/s.

WiFi - 1991

O WiFi, WaveLan 1991 &.

WiFi ( 802.11) 1996.

54Mb/s.

1809 VanSoemmerring 1820 . Oersted 1831 Faraday 1837 Morse 1876 Bell 1897 Strowger 1901 Marconi 1905 Fessenden 1907 1921 1928 Farnsworth 1931 1933 FM Armstrong 1934 RADAR 1937 PCM Reeves 1937 1939 1945 Clarke 1948 Shannon 1962 1970 1971 ISDN 1973 Ethernet 1974 1978 1978 Global Positioning System (GPS) 1986 SONET I SDH 1991 GSM 1996 DSL 1998 1999 LMDS 2000 GPRS 2001 UMTS -data

.

. , V=V(t), I=I(t) P=P(t)

x(t) [xmin,xmax].

y(t) xi [xmin,xmax].

0 2 4 6 8 10-1.5

-1

-0.5

0

0.5

1

1.5

t (msec)

V (

t)

Analog Signal

0 2 4 6 8 10-0.5

0

0.5

1

1.5

t (msec)

V (

t)

Digital Signal

x(t)

2( ) ( )P t x t

x(t)/ 2

2

/ 2

1lim ( )

T

avT

T

P x t dtT

x(t)

2 ( )E x t dt

-10 -5 0 5 100

5

10

15

20

x

t (msec)

: ti t.

x(ti) . 20 ( 0 19).

T .

Rs , Rs=1/T symbols/s

0 1 bits

Rs bit/s

.

(.. video) (.. PC).

(0 1).

(.. ).

: .. .

.

.

(.. ) (.. ASK) ?

. (.. ) PCM (Pulse Code Modulation).

:

)

)

kTt(k+1)T z(t)=mi xix(kT) xi+1 mi=(xi+xi+1)/2

x14

x15m14

(!)

Shannon/yquist: x(t) B x(kT) fs=1/T 2

.

Harry Nyquist Claude Shannon

: Fourier

x(t) , >0 x(t+T)=x(t)

2( ) m

j f t

m

m

x t X e

fm=m/T, j=(-1)1/2 m :

/ 2

2

/ 2

1( )e m

T

j f t

m

T

X x tT

Fourier ( ) exp(j2fmt)

Fourier . t fm.

-10 -5 0 5 100

0.5

1

1.5

x (

t)

t (msec)

:

1

1 1

1

/ 2/ 2

2 2

/ 2 / 2

11 11

1

1 1 1( )e e

2

sinsinc

m m m m

TT

j f t j f t j f T j f T

m

mT T

m

m

m

X x t dt dt e eT T j f T

f TT Tf T

T f T T

1

sinc(x) 1 x=0 sin(x)/(x) x0

To 1/ Rs

H sinc

-10 -5 0 5 10-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

x

sin

c( x

)

Sinc Function

sinc(x)=sin(x)/(x) x=m m0

x, sinc(x)

sinc !

Fourier fm

:

-3 -2 -1 0 1 2 3

x 104

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Xm

fm

(Hz) -3 -2 -1 0 1 2 3

x 105

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Xm

fm

(Hz)

Rs=103Hz Rs=10

4Hz

fm Xm .

, o W W=2fk fk |Xk|

2/maxm{|Xm|2}=L L

Fourier

; x(t) T=+.

Fourier X(f) :

2( ) ( ) j ftx t X f e df

2( ) ( ) j ftX f x t e dt

Fourier X(f) :

Fourier .

:

-2 -1 0 1 20

0.5

1

1.5

x (

t)

t (msec)

1

X(f).

O f=1/T1. , W=2/T1

1

1 1

1

/ 2

2 2

1 1

/ 2

1( ) ( ) sinc

2

T

j fT j fTj ft j ft

T

X f x t e dt e dt e e T fTj f

-1 -0.5 0 0.5 1

x 104

-4

-2

0

2

4

6

8

10x 10

-4

X (

f)

f (Hz)

x(t)

To (f) x(t)

0 0.5 1 1.5 2 2.5 3 3.5 4-0.5

0

0.5

1

1.5

t (msec)

x (

t)

t1 t2

T

2

1

2 1

1

2 2

22

( ) ( )

1

2

sinc

t

j ft j ft

t

j ft j ft

Tj f t

X f x t e dt e dt

e ej f

Te fT

x(t) , X(f) !

,

*

2 2 *( ) ( ) ( ) ( )j ft j ftX f x t e dt x t e dt X f

X(f) H(f)

H(f)

( ) ( ) ( )R R inV f H f V f ( ) ( ) ( )C C inV f H f V f

1

1

2 1( )

2 12C

j CfH f

j fRCj Cf R

1

2( )

2 12R

R j fRCH f

j fRCj Cf R

-4 -2 0 2 4

0

0.2

0.4

0.6

0.8

1

f (KHz)

| HR (

f)|

2

-4 -2 0 2 4

0

0.2

0.4

0.6

0.8

1

f (KHz)

| HC

( f

)|2

, !

, .

.

Maxwell (t) (t)

!

!

!

!

DSL !

!

!

!

!

!

!

,

c=3108m/sec.

f, o =c/f. cos(2ft) T=1/f.

. , , .

.

, .

- .

(.. ) .

, , .

(RF)

Extremely Low Frequency (ELF): (3Hz 30Hz)

Super Low Frequency (SLF): (30-300Hz).

Ultra Low Frequency (ULF): (300-3000Hz)

Very Low Frequency (VLF): (3KHz-30KHz).

Low Frequency (LF): , , (30Hz 300KHz).

Medium Frequency(MF): , (300-3000KHz)

High Frequency (HF): , (3-30MHz).

Very High Frequency (VHF): FM, (30MHz 300MHz).

Ultra High Frequency (UHF): , , , (300MHz-3000MHz)

Super High Frequency (SHF): , , (3GHz-30GHz).

Extremely High Frequency (ELF): .

(0.3GHz-300GHz)

RF

WiFi (802.11) Bluetooth 2.4GHz. internet .

WiMAX (802.16) 2.3GHz, 2.5GHz, 3.5GHz 5.8GHz. DSL.

Cable TV internet .

.

H(f) .

Y(f)=X(f)H(f) (f) .

, . H(f) .

-5 0 5

0

2

4

6

8

10

x 10-4

f (KHz)

X(f

)

-5 0 5

0

0.2

0.4

0.6

0.8

1

f (KHz)

H(f

)

-5 0 5

0

2

4

6

8

10

x 10-4

f (KHz)

Y(f

)

-3 -2 -1 0 1 2 3

0

0.2

0.4

0.6

0.8

1

t (msec)

y(t)

-3 -2 -1 0 1 2 3

0

0.2

0.4

0.6

0.8

1

t (msec)

x(t)

x(t) X(f) H(f) Y(f)=H(f)X(f) y(t)

-5 0 5

0

0.2

0.4

0.6

0.8

1

f (KHz)

H(f

)

-5 0 5

0

2

4

6

8

10

x 10-4

f (KHz)

Y(f

)

-3 -2 -1 0 1 2 3

0

0.2

0.4

0.6

0.8

1

t (msec)

y(t)

.

f H(f). L=max{H(f)} .

H(f) f, Y(f)=X(f)H(f)=LX(f) y(t)=Lx(t) L=y(t)/x(t)

L .

(dB).

!

1010logL dB L

2

2

( )

( )

out

in

P y tL

P x t

dB

dBm

10(mW)

10log1mW

PP dBm

L1x(t) L2 L3 L4 y(t) 4 3 2 1out

in

PL L L L

P

4 3 2 1(dBm) (dBm) (dB) (dB) (dB) (dB)out inP P L L L L

,

0dB 1

3dB 2

10dB10

20dB 102

30dB 103

.

0dBm 1mW

10dBm 10mW

20dBm 100mW

.

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