TRUYỀN SỐ LIỆU VÀ MẠNG Ch01 transmission media and phy layer

Data Communication and
Networking
Dr. –Ing. Vo Que Son
Email:

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

1


Content
Chapter 1: Transmission Media and PHY Layer
Wired and Wireless Media
Physical layer standards: RS232, RS422, RS485
Line Coding
Digital modulation/demodulation
Channel parameters
Gaussian noise and BER

Chapter 2: Data Communication
Asynchronous data transmission
Synchronous data transmission
Channel Coding
Data Compression
Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

2


Wired Media
 Guided Media
 How can signal be transmitted in wired media
(cables)?
 Voltage is sometimes referred to as electromotive
force (EMF).
 EMF is related to an electrical force, or pressure,
that occurs when electrons and protons are
separated

Force within a atom

Static Electricity

neutron
proton

Electrostatic discharge
Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

3


Waves

Sine Wave

Square Wave

• Repeat the same pattern at
regular intervals

• Repeat the same pattern at regular
intervals.

• Continuous voltage

•do not continuously voltage.

• occur naturally and change
regularly over time

• Repeat the flat pattern on both the
top and bottom of the wave

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

4


Two-wire open lines
Used in short distance communication with low data
rates
Simple structure
Data rate < 19Kbps, max distance L<50m
Sensitive with Crosstalk
Sensitive with EMI

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

5


Twisted-Pair Cable
Used in LAN and
Telephone networks
Data or voice transmission
UTP, STP, ScTP
Reduce more EMI than
two-wire open lines?
Reduce Crosstalk?
Introduce Skew: delay in

video transmission

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

6


Noise cancellation

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

7


UTP - Unshield Twisted Pair
 Intrinsic Impedance: 100 Ohm
 BW: depending on CAT
 Speed: 10,100, 1000 Mbps depending on cable
quality/category
 Average $ per node: less expensive
 Maximum cable length: 100m
 Media and connector size: small

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

8


STP - Shield Twisted Pair
Intrinsic Impedance: usually 150 Ohm
Speed: 10,100 Mbps depending on cable
quality/category
Average $ per node: moderately expensive
Maximum cable length: 100m
Media and connector size: medium to large

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

9


ScTP - Screen Twisted Pair
Intrinsic Impedance: usually 100 Ohm
Speed: 10,100, 1000 Mbps depending on cable

quality/category
Average $ per node: less expensive
Maximum cable length: 100m
Media and connector size: small

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

10


Most of common cables
Name
Level 1
Level 2
Cat3
Cat4
Cat5
Cat5e
Cat6
Cat6a

Type

Class F

S/FTP 600 MHz

UTP
UTP
UTP
UTP
UTP

Class Fa
Telecomm. Dept.
Faculty of EEE

Bandwidth
0.4 MHz
4 MHz
16 MHz
20 MHz
100 MHz
100 MHz
250 MHz
500 MHz

1000 MHz

Applications
Telephone and modem lines
Older terminal systems, e.g. IBM 3270
10BASE-T and 100BASE-T4 Ethernet
16 Mbit/s Token Ring
100BASE-TX & 1000BASE-T Ethernet
100BASE-TX & 1000BASE-T Ethernet

10GBASE-T Ethernet
10GBASE-T Ethernet
Telephone, CCTV, 1000BASE-TX in the
same cable. 10GBASE-T Ethernet.
Telephone, CATV, 1000BASE-TX in the same
cable. 10GBASE-T Ethernet.
DCN
HCMUT

11


Cable and connectors

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

12


Cabling Types
 Switch to router
 Switch to PC or server
 Hub to PC or server








Telecomm. Dept.
Faculty of EEE

Switch to switch
Switch to hub
Hub to hub
Router to router
PC to PC
Router to PC
DCN
HCMUT

13


Co-axial Cable
Speed: 10-100 Mbps
Average $ per node:
inexpensive
Media and connector size:
medium
Max cable length: 500m

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

14


Co-axial Cable (1)
 Applications: Computer Networks, Data Systems,
CATV, Private Video Networks
 RG-6/RG-59: 75 Ohm, CATV
 RG-8/ RG-58: 50 Ohm, Thick and Think Ethernet
LANs
 RG-62: 93 Ohm, used in IBM Mainframe
EMI prevention
Many kinds of intrinsic impedances: co-axial cables
can be used in specific systems

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

15


Optical fiber
The light used in optical fiber networks is one type of
electromagnetic energy.
The wavelength of an electromagnetic wave is

determined by how frequently the electric charge
that generates the wave moves back and forth

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

16


Reflection and Refraction
 Electromagnetic waves
pointing out from the source
are called rays
 When a ray of light (the
incident ray) strikes the
shiny surface of a flat piece
of glass, some of the light
energy in the ray is reflected

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

17

Total internal reflection

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

18


Multi-mode fiber

Subscriber Connector (SC) is used in
multimode
Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

19


Single-mode fiber

Straight Tip (ST) connector is used single
mode

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

20


Attenuation

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

21


Optical components
 A LED producing infrared light with wavelengths of either
850nm or 1310nm. LEDs are used in multimode
 LASER producing a thin beam of intense infrared light usually
with wavelengths of 1310nm or 1550 nm. Lasers are used
with single-mode

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

22


Fiber: characteristics
 Fiber-optic cable is not affected by the sources of external
noise
 Fiber in a cable does not generate interference that disturbs
transmission on any other fiber
 The scattering of light, Absorption, Dispersion, manufacturing
irregularities
 Expensive and complicated installation

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

23


Cabling Evolution
Telephone
Informatics
Unstructured
Structured
Universal Cabling System

Pre-engineered Cabling System

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

24


Cabling Evolution (1)
 Telephony

PABX

Telecomm. Dept.
Faculty of EEE

DCN
HCMUT

25