Introduction for telecommunication technology basic terms and concepts. Referring the wikipedia, Slideshare and lecture note of Fudan university. I got a reference documents from Google.

1. Telecommunication Basics
Brian (Yoohyun) Kim
Product Marketing manager at CDNetworks
March, 2015

2. Contents • What is Telecommunication?
• Basic terms and concepts of Telecommunication
• Technical overview of the telephone service
• Cellular Telephony
• Residential internet access service

3. What is Telecommunication?
• Telecommunication
 Telecommunication occurs when the exchange of information between two entities
(communication) includes the use of technology. Communication technology uses channels to
transmit information (as electrical signals), either over a physical medium (such as signal cables),
or in the form of electromagnetic waves.
• Basic elements
 A transmitter that takes information (e.g. voice or text) and converts it to a signal.
 A transmission medium, also called the "physical channel" that carries the signal. An example of
this is the "free space channel, copper wire, coaxial cable or Fiber Optic cable, etc.".
 A receiver that takes the signal from the channel and converts it back into usable information.
 Transceiver: a single box of electronics working as both a transmitter and a receiver, or a
transceiver. For example, a cellular phone is a transceiver.
• Communication Channel
 The term "channel" has two different meanings. In one meaning, a channel is the physical
medium that carries a signal between the transmitter and the receiver.
 The other meaning of the term "channel" in telecommunications is seen in the phrase
communications channel, which is a subdivision of a transmission medium so that it can be
used to send multiple streams of information simultaneously.
*Source: Wikipedia – “Telecommunication”, http://en.wikipedia.org/w/index.php?title=Telecommunication&redirect=no

4. Basic Terms and Concepts
• Half duplex vs Full duplex
 A duplex communication system is a point-to-point system, usually in fixed-line telephone
network, composed of two connected parties or devices that can communicate with one
another in both directions.
 In a full duplex system, both parties can communicate to the other simultaneously. An example
of a full-duplex device is a telephone
 In a half-duplex system, there are still two clearly defined paths/channels, and each party can
communicate to the other but not simultaneously; the communication is one direction at a time.
An example of a half-duplex device is a walkie-talkie.
Full-duplex communication system
Half-duplex communication system
*Source: Wikipedia – “Duplex (Telecommunications), http://en.wikipedia.org/wiki/Duplex_(telecommunications) ”

5. Basic Terms and Concepts
• Modulation
 The shaping of a signal to convey information is known as modulation. Modulation can be used
to represent a digital message as an analog waveform. This is commonly called “Keying”.
 Modem: “Modulator – Demodulator”, A to D and D to A because the voice network is analog.
• Analog Signaling vs Digital Signaling
 Analog signaling: Human friendly | AM, FM | Noise cancellation (Signal tuning is the core
technology)
 Digital signaling: Computer friendly | Error correction, Encryption enabled
*Source: Wikipedia – “Telecommunication”, http://en.wikipedia.org/w/index.php?title=Telecommunication&redirect=no

6. Basic Terms and Concepts
• Switching (“The Cloud”)
 Switching makes better use of the “Cloud”
 Circuit switching, Packet switching (Internet), Broadcasting, Cellular
• Voice network vs Data network
 Voice network: PSTN (Public Switched Telephone Network)
 Basically transmitting the voice
 Data network: LAN, WAN (often (usually) use voice network transmission facilities)
 Anything goes (e.g. text, image, voice, video, etc.)
• Where do networks come from?
 Voice network: Telcos, Long distance carriers
 Data network: ISP (Internet Service Provider)

7. Basic Terms and Concepts
• Circuit vs Packet switching
 Circuit switching is old and expensive, and it is what PSTN uses
 Packet switching allows traffic to be routed around failures
*Source: IP Routing Tutorial, Stefan Fouant, Slideshare
• End-to-end circuit
• Sequenced communication
• PSTN
• Traditional telephony
• Not cost efficient
• Less Delay
• Highly reliable, but failures typically mean
the circuit must be rebuilt
• Packets represent piece of data
• Unordered transmission
• Internet
• VoIP
• Shared cost model
• Highly Delay
• Less reliable, but can reroute around
failures
Circuit Switching Packet Switching

8. Basic Terms and Concepts
• Multiplexing
 Multiplexing is the set of technique that allow the simultaneous transmission of multiple signals
across a single data link (transmission medium)
 Multiplexor is a mechanism that implements the concept
*Source: Introduction 1-1 Circuit Switching: FDM and TDM, Sandra4211, Slideshare

9. Basic Terms and Concepts
• Internet – computer networks that communicate with each other using Internet
Protocol
 Any computer on the Internet can send a message to any other computer using its IP address.
 For the Internet, the physical medium and data link protocol can vary several times as packets
traverse the globe. This is because the Internet places no constraints on what physical medium
or data link protocol is used.
 At the network layer, things become standardized with the Internet Protocol (IP) being adopted
for logical addressing.
 At the transport layer, most communication adopts either the Transmission Control Protocol
(TCP) or the User Datagram Protocol (UDP).
 Above the transport layer, there are certain protocols that are sometimes used and loosely fit in
the session and presentation layers, most notably the Secure Sockets Layer (SSL) and Transport
Layer Security (TLS) protocols.
 Finally, at the application layer, are many of the protocols Internet users would be familiar with
such as HTTP (web browsing), POP3 (e-mail), FTP (file transfer), IRC (Internet chat), BitTorrent
(file sharing) and XMPP (instant messaging).
*Source: Wikipedia – “Telecommunication”, http://en.wikipedia.org/w/index.php?title=Telecommunication&redirect=no

10. Technical elements of Voice network (PSTN)
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
• The Access System consists of the access line to the customer (called the Local Loop)
and termination equipment at the end office (the nearest telephone office switch).

11. PSTN: Mostly Digital with Analog Local Loops
• Today, everything is digital except for the Local Loop access line and residential
telephones.
• The actual Local Loop line can carry either analog or digital signals, but the equipment
at both ends is analog.
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
Sound
Wave
Analog
(Analogous)
Electrical Signal
Residential Telephone
(Analog)
Local Loop
(Analog)
PBX
(Digital)
Local Loop
(Digital)
Switch
(Digital)
Switch
(Digital)
Switch
(Digital)
Trunk Line
(Digital)
Example of today’s Telephone network

12. Codec at the End Office Switch
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
• A Codec at the end office translates between residential analog and PSTN digital
signaling
 ADC = Analog to Digital conversion
 DAC = Digital to Analog conversion
• Analog-to-Digital Conversion (ADC): Bandpass Filtering and Pulse Code Modulation
(PCM)
 Human voice bandwidth: 300Hz to 3,400Hz (3.1KHz bandwidth) – about 4KHz
 Nyquist sampling theory: Signals must be samples at twice their high frequency (1 / 8,000
second sampling, 8-bit sampling, 8,000 bytes/sec, 64Kbps)
Switch
(Digital)
Telephone
(Analog)
Codec
DAC
ADC
Local
Loop
Home End Office
Analog
Signal
Digital
Signal

13. Voice over IP (VoIP)
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
• Voice over Internet Protocol
 Voice over Internet Protocol (VoIP) allows data packets to be used for synchronous voice
communications. The data packets are marked as voice type packets and can be prioritized by
the network administrators so that the real-time, synchronous conversation is less subject to
contention with other types of data traffic which can be delayed (i.e. file transfer or email) or
buffered in advance (i.e. audio and video) without detriment.
 With IP, there is no wasted capacity as there is with circuit switching and this reduces cost.
 Stations can be special IP telephones with IP functionality or a PC with multimedia hardware and
VoIP software. IP phones need a Codec to convert voice analog signals form the microphone into
digital IP signals.
PC with
Multimedia Hardw are
and VoIPSoftware
IPTelephone
w ith
Codec and
TCP/IPFunctionality
Media
Gatew ay
PSTN
Internet

14. Cellular Telephony
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
• Microwave uses radio transmission for PSTN trunk lines
 Each circuit is sent in a separate channel and if each channel bandwidth is large, there will be
fewer channels.
 Frequency Division Multiplexing (FDM) used in AMPS (Advanced Mobile Phone System.)
 Voice uses 4 KHz-wide channels.

15. Cellular Telephony
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
• In Cellular technology, the region is divided into smaller cells.
 In each cell, a Cellsite (Base Station) serves cellphones in the cell.
 When a subscriber moves from one cell to another in a cellular system, this is called a handoff.
 When a subscriber moves from one city to another, this is roaming.
 The Mobile Telephone Switching Office (AKA Mobile Switching Center) coordinates the Cellsites
and implements signaling and handoffs.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Channel
47
Mobile Telephone Sw itching Office
Cellsite
PSTN
Handoff

16. GSM (Global Service for Mobile communication)
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
• GSM is the worldwide standard for cellular voice – especially Europe.
 Uses Time Division Multiplexing (TDM)
 Uses 200 kHz channels
 Divides each second into many frame periods
 Divides each frame into 8 slots
 Gives same slot in each frame to a conversation
Slot 1
Conversation
A
Slot 2
Conversation
B
Slot 8
Conversation
H
……
Slot 1
Conversation
A
Time Frame 1 Frame 2

17. CDMA (Code Division Multiple Access)
*Source: Business Data networks and Telecommunications, Panko, University of Hawaii
• Code Division Multiple Access (CDMA)
 Used in the United States and Korea | A form of spread spectrum transmission
 Unlike traditional spread spectrum technology, multiple users can transmit simultaneously
 1.25 MHz channels | Can support many users per channel
• Can use the same channel in adjacent cells
 So can only reuse a channel in every cell

18. 3G Services
• 3G – Third generation of mobile telecommunication technology
 This is based on a set of standards used for mobile devices and mobile telecommunications use
services and networks that comply with the International Mobile Telecommunications-2000
(IMT-2000) specifications.
 3G finds application in wireless voice telephony, mobile Internet access, fixed wireless Internet
access, video calls (e.g. show) and mobile TV.
 The original and most widespread radio interface is called WCDMA (Wideband CDMA).
• HSPA (High Speed Packet Access)
 HSPA is that extends and improves the performance of existing 3rd generation mobile
telecommunication networks utilizing the WCDMA protocols.
 HSDPA: The first step required to upgrade WCDMA to HSPA is to improve the downlink by
introducing HSDPA. The improved downlink provides up to 14 Mbit/s with significantly reduced
latency.
 HSPA+ (evolved High Speed Packet Access): Evolved HSPA provides data rates up to 84 Mbit/s in
the downlink and 10.8 Mbit/s in the uplink (per 5 MHz carrier) with multiple input, multiple
output (2x2 MIMO) technologies and higher order modulation (64 QAM). With Dual Cell
technology, these can be doubled.
*Source: Wikipedia – “High Speed Packet Access”, http://en.wikipedia.org/wiki/High_Speed_Packet_Access

19. LTE – Long Term Evolution
• LTE – Long Term Evolution
 LTE, commonly marketed as 4G LTE, is a standard for wireless communication of high-speed data
for mobile phones and data terminals. It is based on the GSM/EDGE and UMTS/HSPA network
technologies, increasing the capacity and speed using a different radio interface together with
core network improvements.
 Peak download rates up to 299.6 Mbit/s and upload rates up to 75.4 Mbit/s depending on the
user equipment category (with 4×4 antennas using 20 MHz of spectrum). Five different terminal
classes have been defined from a voice centric class up to a high end terminal that supports the
peak data rates. All terminals will be able to process 20 MHz bandwidth.
• Voice Calls
 Voice over LTE (VoLTE) vs VoIP
 Circuit-switched fallback (CSFB): TE just provides data services, and when a voice call is to be
initiated or received, it will fall back to the circuit-switched domain.
 Simultaneous voice and LTE (SVLTE): the handset works simultaneously in the LTE and circuit
switched modes, with the LTE mode providing data services and the circuit switched mode
providing the voice service.
*Source: Wikipedia – “LTE (Telecommunications)”, http://en.wikipedia.org/wiki/LTE_(telecommunication)

20. Residential Internet Access Services
*Source: Business Data networks and Telecommunications, Panko University of Hawaii
• Telephone modems: 56Kbps (not 64Kbps since voice also should be delivered)
• ISDN: 64Kbps-128Kbps
1st Gen
Late90’s-
Early 2000
2nd Gen
Early -
Mid 2000
3rd Gen
Late 2000 -
Current
4th Gen
2013 -
Beyond
• ADSL: 8Mbps (DL), 1Mbps (UL)
• VDSL: 52Mbps (DL), 6.4Mbps (UL)
• FTTH: 100Mbps
• Mobile Broadband
• 4G / 5G (1Gbps)
*Akamai acquires Netli in 2007

21. Telephone Modem Connection to an ISP
*Source: Business Data networks and Telecommunications, Panko University of Hawaii
& Wikipedia, “Modem”
Client A
Telephone
Modem
Telephone
PSTN (Digital)
33.6 kbps
Digital
Analog
Access
Line
Analog
56 kbps
• Telephone modem
 Telephone modems convert digital computer signals to analog telephone signals.
 Very low transmission speeds. Long delays in downloading webpages. Subscriber cannot
simultaneously use the telephone line for voice calls.
 Modems are generally classified by the amount of data they can send in a given unit of time,
usually expressed in bits per second (symbol bit/s, sometimes abbreviated "bps"), or bytes per
second (symbol B/s). Modems can also be classified by their symbol rate, measured in baud.

22. ADSL: Asymmetrical Digital Subscriber Line
• Asymmetric digital subscriber line
 Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a
data communications technology that enables faster data transmission over copper telephone
lines than a conventional voice band modem can provide. It does this by utilizing frequencies
that are not used by a voice telephone call.
 A splitter, or DSL filter, allows a single telephone connection to be used for both ADSL service
and voice calls at the same time.
PC
ADSL
Modem
Ordinary Telephone
Service
Single Pair of
Voice-Grade
UTPWires
Dow nstreamData
Up to 1.5 Mbps
UpstreamData
Up to 512 kbps
Splitter DSLAM
Telephone
Telephone Company
End Office Sw itch
Subscriber
Premises
Data
WAN
PSTN
*Source: Business Data networks and Telecommunications, Panko University of Hawaii
& Wikipedia, “Asymmetrical digital subscriber line”

23. Thank you
Brian (Yoohyun) Kim
Product Marketing Manager| CDNetworks
brian.Yoohyun.kim@gmail.com
http://yoohyunkim.blogspot.com