Download Introduction - McMaster University > ECE

Appendix 1
Evolution of Telecommunication Technology
1. Telecommunication network physical layer architecture
Customer
Premises
Network
Access
Network
Core Network
Access
Network
User Network Interface
Customer
Premises
Network
User Network Interface
Subscriber Network Interface
Access Network: (Local and Metropolitan Network) Cross-Connection, Multiplexing, Short Haul
Transport
Core Network: (Transport and Packet-Switch Network) Packet-Switch, Multiplexing, Long Haul
Transport
2. Point-to-point lightwave communication system
Electrical
Signal Source
Optical
Transmitter
E-O Conversion
Fiber Link
Optical Signal
Transmission
Optical
Receiver
Electrical
Signal Source
O-E Conversion
1. Fundamental requirements: Accuracy and Efficiency
2. Fundamental elements: Channel and Node
Channel: signal transmission
Node: signal processing
3. As the transmission media, optical fiber has many advantages
4. Serving for optical fiber, opto-electronic devices are used as the E-O/O-E converters
5. Integrated photonic device will be used as the node for signal processing as well, but just
at the beginning stage
1
6. Current status: lightwave transmission or photonic technology is mainly used for point-topoint communication systems in Transport Network, and begins to enter into Access
Network
7. Future: the application of photonic technology will not only be in the signal transmission
part (channel) of the networks, but also be in the signal processing part (node).
3. Telecommunication technology evolution
1. Basic Technology and Services (Legacy Synchronous Communication Networks)
Basic technology:
Plain Old Telephony Service (POTS): Purely analog (acoustical) signal transmission through
twisted pair of copper wires named as Tip and Ring (T&R).
PCM and DS0: Analog (acoustical) signal (high cut-off at 3.4kHz) – PCM through CODEC
(sampling rate 8000/s, 8-bit coding) at 64Kb/s named as Digital Signal level 0 (DS0). A
frame is defined as the time length required for a single sample: 125s, therefore, a DS0
frame contains 8 bits or 1 byte.
TDM: At the User-to-Network Interface (UNI) where the user signal (64Kb/s data stream
organized in DS0 frames: 8-bit bytes) first meets the network, signals from many users
arrive. These signals are synchronized with the system clock: 8kHz or a multiple of it. The
signals are sequentially polled one byte at a time and placed one after the other in a fixed
order, known as byte interleaving.
DS1: Formed by 24 DS0 signals through TDM. A DS1 frame contains 24 bytes (each byte
from 24 different signals) and an additional bit named as F-bit for frame marking. A DS1
frame contains 248+1=193(bits), since the time length of a frame is 125s, DS1 bit rate is
193bits/125s=1.544Mb/s. The function of this time-division multiplexer converts DS0 to
DS1 is known as a M1 multiplexer. The F-bit constitute a subrate channel of 8Kb/s, it has
three functions: framing, data link over which network data are sent between the
transmitting and receiving end, error control.
Basic transmission media:
The copper twisted-pair cable that connects most homes (user or subscriber equipment) with
the telephone service provider equipment, known as the local loop, is the traditional
transmission medium for analog signals up to 3.4kHz. When the transmitted information
over the loop is in digital form, the loop is known as a Digital Subscriber Line (DSL).
DSL is a digital technology that can deliver high bit rates of DS1 and in some case up to
7Mb/s over existing twisted-pair copper cable. A digital signal transmitted over DSL
requires modulation. It can be deployed in many digital transmission services including
Internet.
2
DS1 signal can be transmitted through a pair of copper wires known as T1 line. An amplifier
is required after 3,000 ft from user and every 6,000 ft between amplifiers, however, 50 is the
maximum number of the amplifiers can be placed before signal regeneration.
Basic services:
BR-ISDN: Basic Rate Integrated Service Digital Network uses two 64Kb/s channels
(channel B) and a 16Kb/s channel (channel D) to support a combination of voice and/or data
services over a single pair of wires.
ISDN: Two pairs, downstream bit rate 144Kb/s, upstream 144Kb/s, maximum length of loop
18,000 ft.
xDSL: Single or two pairs bit rate from 768Kb/s to 6Mb/s, maximum length of loop
from12,000 ft to 18,000 ft.
2. Hierarchical Multiplexing
1
2
24
F
DS1:
1.544Mb/s 1
T1 2
M
1
4
C
DS2:
6.312Mb/s 1
T2 2
M1
2
7
C
DS3:
44.736Mb/s
T3
M2
3
DS1: 24DS0 TDM (1 F-bit/24 DS0s)
DS2: 4DS1 Bit Interleaving Multiplexer (1 C-bit after every 48 payload bits)
DS3: 7DS2 Bit Interleaving Multiplexer (1 C-bit after every 84 payload bits)
Stuffing bits are required to compensate DS1/DS2 signals at slightly different bit rates.
3
Legacy Telecommunication System
T&R (TP at Analog 3.4kHz)
Center
Office
Analog Line
Interface Unit
Analog Subscriber
Interface Unit
(LP Filter)
Customer Premises
Equipment
DS0/1B (TP at Digital 64Kb/s)
Center
Office
Digital Line
Interface Unit
Digital Subscriber
Interface Unit
(CODEC)
Customer Premises
Equipment
BR-ISDN/(2B+D) (TP at Digital 144Kb/s)
Center
Office
Digital Line
Interface Unit
Digital Subscriber
Interface Unit
(TCM/ECH)
Customer Premises
Equipment
DS1/T1 (TP at Digital 1.5Mb/s)
Center
Office
Digital Line
Interface Unit
Digital Subscriber
Interface Unit
(M1)
Customer Premises
Equipment
HDSL (TP at Digital 768Kb/s)
ADSL (STP at Digital D-6Mb/s U-640Kb/s)
Center
Office
Digital Line
Interface Unit
Digital Subscriber
Interface Unit
(2B1Q/DMT/CAP)
Customer Premises
Equipment
Digital Subscriber
Interface Unit
(M12)
Customer Premises
Equipment
DS2/T2 (STP at Digital 6Mb/s)
Center
Office
Digital Line
Interface Unit
DS3/T3 (Coax/RF at Digital 45Mb/s)
Center
Office
Coax/RF
Line Interface
Unit
Coax/RF
Subscriber
Interface Unit
Customer Premises
Equipment
(M12)
4
4. Synchronous digital hierarchy (SDH)/Synchronous optical networking (SONET)
SDH/SONET
OC3,12,48,192 (Fiber at Digital 155Mb/s, 622Mb/s, 2.5Gb/s, 10Gb/s)
Centre
Office
Fiber Line
Interface Unit
(O-E)
Fiber Subscriber
Interface Unit
(E-O)
Customer Premises
Equipment
SONET Multiplexing Structure
DS1
1.544Mb/s
E1
2.048Mb/s
DS1C
3.152Mb/s
DS2
6.312Mb/s
VT1.5 SPE
VT1.5
VT2 SPE
VT2
VT3 SPE
VT3
Legend
4
3
Pointer Processing
VT Group
2
Multiplexing
1
VT6 SPE
VT6
Mapping
7
DS3 44.736Mb/s
ATM 48.384Mb/s
STS1 SPE
E4 139.264Mb/s
STS3c SPE
1
1
STS-1
N
STS-3c
N/3
STS-N
ATM 149.760Mb/s
Reference:
ANSI T1.105, “Draft Proposed American National Standard for Telecommunications-Digital
Hierarchy-Synchronous Optical Networks (SONET)”
5
SDH Multiplexing Structure
DS4NA
139.264Mb/s
ATM
149.760Mb/s
E3
34.368Mb/s
DS3
44.736Mb/s
ATM
48.384Mb/s
C4
C3
VC4
VC3
TU3
1
TU
G3
3
DS1
1.544Mb/s
DS1A
2.048Mb/s
C2
C12
VC2
VC12
TU2
TU12
1
TU
G2
3
4
1
3
7
VC3
DS2
6.312Mb/s
AU4
AU
G

N
STM-N
AU3
7
Legend
Pointer Processing
Multiplexing
DS1
1.544Mb/s
C11
VC11
TU11
Mapping
Aligning
Reference:
ITU-T/R G. 707, “Synchronous Digital Hierarchy Bit Rates”
ITU-T/R G. 708, “Network Interface for the Synchronous Digital Hierarchy”
ITU-T/R G. 709, “Synchronous Multiplexing Structure”
ITU-T/R G. 803, “Architectures of Transport Networks Based on the Synchronous Digital
Hierarchy”
5. Legacy data networks
Legacy synchronous communication networks do not address the requirements for voice and
data applications in an equitable manner.
Primary concerns in voice communication networks: short delay of the signal through the
network; in data applications: high bit rate and low cost per unit time.
The contrasting needs of these applications brought to bear a data network able to transport
chunks of data, known as packets (about 9,000 bytes). Such systems are the Local Area
Network (LAN), the Metropolitan Area Network (MAN), the Wide Area Network (WAN)
and the Switched Multi-megabit Data Services (SMDS).
6
LAN networks are of two major types: Ethernet and Ring.
Ethernet LANs are hierarchical and the transmission rate is at 10 or 100Mb/s.
FDDI (Fiber Distributed Data Interface) is a counter-rotating fiber ring LAN specified at
100Mb/s effective data rate.
Technology Hierarchy:
Transmission media – Components – Point-to-point system - Network topology –
Transmission protocol
7