1. GSI 640
Telecommunications
Overview
Raúl Soto
• Joel Maysonet
• Lucette Sánchez
• Fernando González
JULY 2005

2. How Computers connect to the Web servers
Internet through regular phone lines store the
content that
users access
The Internet backbone is made up through the
The modem inside the Internet. Every
computer connects to the of packet switches, routers, peering
sites/NAPs, and extensive fiber web site is
phone line, and dials the stored on a
phone number of the user’s networks that send data from ISPs
to Web servers and back again. Web server.
ISP to connect to the Internet.
The local switch
sends the “call”
through the local
phone lines to the The Internet
ISP.
switch ISP
The ISP’s modems and
servers then connect
the user to the Internet.

3. OSI Layers Model  The Open Systems
Interconnection Reference
Model is a layered abstract
description for communications and
computer network protocol design
 Developed as part of the Open
Systems Interconnect initiative.
 Also called the OSI seven layer
model.
 divides the functions of a protocol
into a series of layers.
 Each layer has the property that it
only uses the functions of the layer
below, and only exports functionality
to the layer above

4. OSI Layers Model

5. X.25
 protocol for packet-switched networks
 used in both private and public data networks
 for a long time, was the predominant international standard
for wide area networks.
 Public X.25 networks - packet switched public data
networks (PSPDN) - have been installed all over the world.

6. X.25
 The general concept of X.25 was to create a universal
and global packet-switched network on what was then the
bit-error prone analog phone system.
 Much of the X.25 system is a description of the rigorous
error correction needed to achieve this, a system
known as LAP-B.
 The X.25 model was based on the concept of establishing
"virtual calls" through the network, with "data terminating
equipment" (DTE's) providing endpoints to users that
looked like point-to-connections.

7. Frame Relay
 packet-switch technology, simpler and more powerful than X.25
 efficient data transmission technique used to send digital information
quickly and cheaply to one or many destinations from one or many
end-points.
 provides a multiplexed channel between a router and a T-1/E-1 nodal
processor.
 increases bandwidth utilization while reducing overall equipment costs
 standard addresses data communications speeds up to 45Mbps.

8. Frame Relay
 Commonly implemented for voice and data as an encapsulation
technique, used between local area networks (LANs) over a wide
area network (WAN).
 Each end-user gets a private line (or leased line) to a frame relay node.
The frame relay network handles the transmission over a frequently-
changing path that is transparent to all end-users
 As of 2005, Frame relay is slowly being displaced by ATM and native IP-
based protocols.
 With the advent of the VPN and other dedicated broadband services
such as cable modem and DSL, the end may be in sight for frame relay
protocol and encapsulation

9. Frame Relay vs X.25
 Up to the early 1990s, X.25 was the only technology that offered
flexible bandwidth
– means that the user only pays for the bandwidth he actually uses
– the technical term is bandwidth on demand
 the introduction of new, sophisticated services demanded higher
network performance, and X.25 was a bottleneck
– limited transmission capacity - usually 64 kbit/s.
 Frame relay was designed to meet these new requirements.
 Today, frame relay is probably the best and most cost-effective
bearer network for interconnecting two LANs.
 Frame relay is commonly known as the X.25 of the 1990s
 Frame relay is the first international standard for data
communication that really works

10. ATM / B-ISDN
 Broadband Integrated Services Digital Network
– In the 1970s the telecommunications industry conceived that digital
services would follow much the same pattern as voice services, and
conceived a grandiose vision of end-to-end circuit switched services,
known as the Broadband Integrated Services Digital Network (B-
ISDN).
– This was conceived as a logical extension of the end-to-end circuit
switched data service, ISDN.
– The technology for B-ISDN was going to be Asynchronous Transfer
Mode (ATM), which was intended to carry both synchronous voice
and asynchronous data services on the same transport.
– The B-ISDN vision has been overtaken by the technology of the
Internet. The ATM technology survives as a low-level layer in most
DSL technologies.
– Over fibre optic lines, the maximum Data bandwidth is 1.5 Megabits
and point-to-point protocol is typically used to carry data over the B
channels.

11. ATM / B-ISDN
 Asynchronous Transfer Mode (ATM)
– cell relay network protocol which encodes data traffic into small
fixed sized (53 byte; 48 bytes of data and 5 bytes of header
information) cells instead of variable sized packets as in packet-
switched networks (such as the Internet Protocol or Ethernet).

12. DSL : Digital Subscriber Line
 DSL technology increases bandwidth for
copper wires, such as those used by
phone companies between their switching
stations and the end-user
(last mile technology).
 DSL works by sending out digital pulses through the high-frequency
region of copper wires, which is not used by the voice channel
 This allows an ordinary phone line to provide digital communication
without blocking access to voice services
 ADSL (Asymmetrical DSL) is the most widely used. Allows up to 8
Mbps downstream and 1 Mbps upstream communications.
 Requires a special type of modem

13. DSL : Digital Subscriber Line
Most DSL users must A user’s DSL provider may also be
be within 18,000 feet his/her ISP, and the connection to
of the DSL-equipped the Internet usually begins here.
central office.
The Internet
DSL switch
modem
ISP
DSLAM
Equipment installed at the switch that
increases the speed and capacity of
regular copper lines and allows them to
send digital signals.

14. DSL Technologies
 Symmetrical Digital Subscriber Line (SDSL) - used typically for
business applications such as video conferencing. The traffic from the
user to the network is upstream traffic, and from the network to the
user is downstream traffic. When the data rate in both directions is
equal, it is called a symmetric service.
 Asymmetrical Digital Subscriber Line (ADSL) - used primarily
by residential users who receive a lot of data but do not send much,
such as Internet surfers. ADSL provides faster speed in a downstream
direction (from the telephone central office to the customer's
premises) than upstream (from customer's premise to the telephone
central office). When the upstream data rate is lower than the
downstream rate, it is called an asymmetric service.

15. DSL Technologies
• ISDN Digital Subscriber Line (IDSL) - provides symmetrical
connection with Integrated Services Digital Network (ISDN), and
is designed to extend DSL to locations with a long distance to a
telephone central office.
• High-data-rate Digital Subscriber Line (HDSL) - provides
fixed symmetrical high speed access at T1 rate (1.5 Mbps), and is
designed for business purposes.
• Very high-data-rate Digital Subscriber Line (VDSL) -
provides both symmetrical and asymmetrical access with very
high bit rate over the copper line. Deployment is very limited at
this time.

16. DSL vs Cable
 Cable modems Internet service offers shared bandwidth or
speed among neighbors on the same cable system.
 Speed is asymmetric and will vary depending on the number of
people on the network.
 DSL Internet service offers a dedicated connection to your
home.
 In most cases, however, the performance of DSL-based service
depends on the distance between end user and phone
company central office.
 High-speed Internet access using cable modems is targeted
towards residential use while DSL-based service is targeted
towards residential and business uses.

17. Mobile Telecommunications
Public Switched
Mobile Switching Telephone Network
Air Interface Office
PSTN
Cell Tower

18. Pre-Cellular Technology
 One Transmitter
 High Power
 Limited Channels
Source: International Engineering Consortium

19. Cellular Architecture
 Many Transmitters
 Low Power
 Frequency Reuse
Source: International Engineering Consortium

20. Cellular Architecture
 Each tower serves one cell
 Each cell uses different
frequencies
 As phone moves from one
cell to another, towers
“handoff” calls

21. Seven Way Frequency Re-use
Cellular networks are
designed so adjacent cells
use different frequencies
Source: International Engineering Consortium

22. Cellular vs PCS
 All mobile telephony providers use “cellular” architecture
 Primarily two different types of FCC licenses are used to
provide mobile telephony: Cellular and PCS (Personal
Communications System)
Cellular PCS
Spectrum 850 MHz 1.9 GHz
Bandwith 2x25 MHz licenses 3x30 MHz licenses
3x10 MHz licenses
Introduced 1980s 1990s
Format Originally analog Originally digital

23. Mobile Telephony Generations
 First Generation – Analog
• AMPS (Advanced Mobile Phone System)
• First cellular standard, used by all cellular licensees
• Represented pioneer analog cellular systems that permitted two-
way voice communications, circuit-switched data transmission

24. Mobile Telephony Generations
 Second Generation - Digital
• TDMA (Time Division Multiple Access) - AT&T
• CDMA (Code Division Multiple Access) - Sprint, Verizon
• GSM (Global System for Mobile Communications)
• Voicestream, Most European Operators
• iDEN (Integrated Digital Enhanced Network) - Nextel
• Uses SMR licenses rather than cellular or PCS
• 2G networks are the first digital mobile telephone networks and
offer voice services such as voice mail and caller ID as well as
Short Messaging Service (SMS)
• Data speeds of 9.6 to 19.2 kbps

25. Mobile Telephony Generations
 Third Generation – Digital
• WCDMA: Wideband Code Division Multiple Access
• CDMA2000 : Code Division Multiple Access
• UMTS : Universal Mobile Telecommunications System
• EDGE : Enhanced Data for Global Evolution
• DECT: Digital Enhanced Cordless Telecommunications
• Called UMTS in Europe
• Currently in development
• 3G technology promises Internet access with speeds up to 2 Mbps
• Combines high-speed mobile access with Internet Protocol (IP) based services.
• Planned 3G services include video and audio streaming and location-based
services
• This doesn't just mean fast mobile connection to the World Wide Web - by
liberating us from slow connections, cumbersome equipment and immovable
access points, 3G will enable new ways to communicate, access information,
conduct business and learn.

26. 1G: First Generation Mobile Telephony
 AMPS : Advanced Mobile Phone System
• Original Standard for analog mobile telephony systems
• Still used in some areas of North America, Latin America, Eastern
Europe, Australia, and parts of Russia and Asia.
• Competes with GSM and CDMA
• To optimize the use of transmission frequencies, AMPS divides
geographic areas into cells
• Each connection uses its own dedicated frequency - of which there
are about 1,000 per cell.
• Two cells can use the same frequency for different connections so
long as the cells are not adjacent to each other.
• The digital IS-136 TDMA standard (often known as D-AMPS) offers
the evolutionary path from analog AMPS.

27. 2G: Second Generation Mobile Telephony
 CDMA : Code Division Multiple Access
• IS-95 based digital technology for delivering mobile telephone
services.
• CDMA systems have been in commercial operation since 1995
• These systems now support over 95 million subscribers worldwide.
• CDMA networks operate in the 800 and 1900 MHz frequency
bands with primary markets in the Americas and Asia.
• Provides for voice and data services up to speeds of 64 kbits/sec, as
well as integrated voice mail and SMS services.
• Marketed using the name cdmaOne.
• The next evolutionary step for 3G services is CDMA2000, or
IS-2000.

28. 2G: Second Generation Mobile Telephony
 TDMA : Time Division Multiple Access
• Also known as D-AMPS
• Technology for digital transmission of radio signals between a
mobile telephone and a radio base station.
• In TDMA, the frequency band is split into a number of channels.
• Each channel is split into three time units, so that three calls can
share a single frequency channel without interfering with one
another.
• Based on the IS-136 standard.
• It is one of the world's most widely deployed digital wireless
systems. PR providers are now switching from CDMA to TDMA
• It provides a natural evolutionary path for analog AMPS networks
• Offers efficient coverage and is well suited to emerging
applications, such as wireless virtual private networks (VPNs)
• Ideal platform for PCS (Personal Communication Services).

29. 2G: Second Generation Mobile Telephony
 GSM : Global System for Mobile Communications
• First introduced in 1991
• One of the leading digital cellular systems.
• Eight simultaneous calls can occupy the same radio frequency.
• GSM simplifies data transmission to allow laptop and palmtop
computers to be connected to GSM phones.
• It provides integrated voice mail, high-speed data, fax, paging and
short message services capabilities, as well as secure
communications.
• It offers the best voice quality of any current digital wireless
standard.
• Originally a European standard for digital mobile telephony, GSM
has become the world's most widely used mobile system in
use in over 100 countries.
• GSM networks operate on the 900 MHz and 1800 MHz waveband
in Europe, Asia and Australia, and on the 1900 MHz waveband in
North America and in parts of Latin America and Africa.

30. 2G: Second Generation Mobile Telephony
 GPRS : General Packet Radio Service
• Packet-linked technology
• Enables high-speed wireless Internet and other data
communications.
• GPRS provides more than four times greater speed than
conventional GSM systems.
• Using a packet data service, subscribers are always connected and
always on line so services will be easy and quick to access.

31. IMT-2000
 International Mobile Telecommunications 2000
• Term used by the International Telecommunication Union (ITU),
a United Nations agency, to describe third generation mobile
telephony standards that meet a number of requirements in
terms of transmission speed and other factors.
• Basic standards in IMT-2000 include:
• IMT-DS (direct spread). WCDMA
• IMT-MC (multi-carrier). CDMA2000
• IMT-TC (time-code) UTRA TDD & TD-SCDMA
• IMT-FT (frequency-time). DECT
• IMT-SC (single carrier). TDMA

32. 3G: Third Generation Mobile Telephony
 WCDMA: Wideband Code Division Multiple Access
• Technology for wideband digital radio communications of
Internet, multimedia, video and other capacity-demanding
applications.
• WCDMA is the dominating 3G technology, providing higher
capacity for voice and data and higher data rates.
• Uses a new spectrum with a 5 MHz carrier, providing 50 times
higher data rate than in present GSM networks, and 10 times
higher data rate than in GPRS networks
• Handles up to 2 Mbps for local area access or 384 Kbps for wide
area access. A coming release will include enhancements up to
more than 10 Mbps.

33. 3G: Third Generation Mobile Telephony
 WCDMA: Wideband Code Division Multiple Access
• WCDMA is also known as UMTS
• Has been adopted as a standard by the ITU under the name
IMT-2000 direct spread.
• The gradual evolution from today's systems is driven by demand
for capacity, which is required by new and faster data based
mobile services.
• WCDMA enables better use of available spectrum and more
cost-efficient network solutions.
• The operator can gradually evolve from GSM to WCDMA,
protecting investments by re-using the GSM core network and
2G/2.5G services.

34. 3G: Third Generation Mobile Telephony
 CDMA 2000: Code Division Multiple Access 2000
• Also known as IS-2000
• 3G technology that can be deployed in several phases.
• The first phase, CDMA2000 1X, supports an average of 144 kbps
packet data in a mobile environment.
• The second release of 1X, called 1xEV-DO can support data rates
up to 2 Mbps on a dedicated data carrier
• The final phase, 1xEV-DV, supports even higher peak rates,
simultaneous voice and high-speed data, as well as improved
Quality of Service mechanisms.
• A key component of CDMA2000 is its ability to support the full
demands of advanced 3G services such as multimedia and other
IP-based services.

35. 3G: Third Generation Mobile Telephony
 EDGE : Enhanced Data for Global Evolution
• A technology that gives GSM the capacity to handle services for
the third generation of mobile telephony.
• EDGE provides three times the data capacity of GPRS.
• Using EDGE, operators can handle three times more subscribers
than GPRS; triple their data rate per subscriber, or add extra
capacity to their voice communications.
• EDGE uses the same TDMA (Time Division Multiple Access)
frame structure, logic channel and 200kHz carrier bandwidth as
today's GSM networks, which allows existing cell plans to remain
intact.

36. 3G: Third Generation Mobile Telephony
 DECT : Digital Enhanced Cordless Telecommunications
• A common standard for cordless personal telephony
• Originally established by ETSI, a European standardization body.
• DECT is a system for cordless business communications.

37. Other Technologies
 Wi-Fi
 Wi-Max
 Voice Over IP
 Bluetooth
 SMS / EMS

38. Wi-Fi
 Wi-Fi (or Wi-fi, WiFi, Wifi, wifi)
• Short for "Wireless Fidelity“
• Set of product compatibility standards for wireless local area
networks (WLAN) based on the IEEE 802.11 specifications.
• New standards beyond the 802.11 specifications, such as
802.16(WiMAX), are currently in the works and offer many
enhancements, anywhere from longer range to greater transfer
speeds.
• Intended to be used for mobile devices and LANs, but is now often
used for Internet access.
• It enables a person with a wireless-enabled computer or personal
digital assistant (PDA) to connect to the Internet when in proximity
of an access point.
• The geographical region covered by one or several access points is
called a hotspot.

39. Wi-Fi : Advantages
• Unlike packet radio systems, Wi-Fi uses unlicensed radio spectrum and
does not require regulatory approval for individual deployers.
• Allows LANs to be deployed without cabling, potentially reducing the
costs of network deployment and expansion. Spaces where cables cannot
be run, such as outdoor areas and historical buildings, can host wireless
LANs.
• Wi-Fi products are widely available in the market. Different brands of
access points and client network interfaces are interoperable at a basic
level of service.

40. Wi-Fi : Advantages
• Competition amongst vendors has lowered prices considerably since their
inception.
• Many Wi-Fi networks support roaming, in which a mobile client station
such as a laptop computer can move from one access point to another as
the user moves around a building or area.
• Many access points and network interfaces support various degrees of
encryption to protect traffic from interception.
• Wi-Fi is a global set of standards. Unlike cellular carriers, the same Wi-Fi
client works in different countries around the world.

41. Wi-Fi : Disadvantages
• Interference
• The 802.11b and 802.11g flavors of Wi-Fi use the 2.4 GHz spectrum
• Possible interference at the 2.4 GHz Wi-Fi band, may cause devices to no
longer function.
• Other possible sources of interference:
• Bluetooth devices
• Microwave ovens
• Cordless phones (900 MHz or 5.8 GHz can be alternative frequencies)
• Video sender devices
• Amateur Radio operators
• Cell phones which use microwave frequencies

42. Wi-Fi : Disadvantages
• Legislation is not consistent worldwide :
• most of Europe allows for an additional 2 channels
• Japan has one more on top of that
• Spain and other countries prohibit use of the lower-numbered
channels.
• Italy and other countries used to require a 'general authorization' for
any WiFi used outside the owned premises
• Power consumption is high compared to other standards, making
battery life and heat a concern.
• Wi-Fi networks have limited range.
• A typical Wi-Fi home router using 802.11b or 802.11g might have a
range of 45 m (150 ft) indoors and 90 m (300 ft) outdoors.

43. Wi-Fi : Disadvantages
• Security:
• The most common wireless encryption standard, Wired Equivalent
Privacy or WEP, is easily breakable even when correctly configured.
• Newer wireless products are slowly providing support for the Wi-Fi
Protected Access (WPA) protocol, many older access points will have
to be replaced to support it.
• The adoption of the 802.11i (aka WPA2) standard in June 2004 makes
available a rather better security scheme for future use — when
properly configured.
• In the meantime, many enterprises have had to deploy additional layers
of encryption (such as VPNs) to protect against interception.

44. Wi-Fi : Disadvantages
• Security:
• Interference of a closed or encrypted access point with other open
access points on the same or a neighboring channel can prevent
access to the open access points by others in the area. This can pose
a problem in high-density areas such as large apartment buildings
where many residents are operating Wi-Fi access points.
• Access points could be used to steal personal information
transmitted from Wi-Fi users.
• Free access points (or improperly configured access points) may be
used by a hacker to anonymously initiate an attack that would be
impossible to track beyond the owner of the access point.

45. Wi-Max
• Short for “Worldwide Interoperability for Microwave Access”
• WiMAX is a wireless metropolitan area network (MAN) technology
that can connect IEEE 802.11(Wi-Fi) hotspots to the Internet and
provide a wireless extension to cable and DSL for last mile broadband
access.
• WiMAX is both faster and has a longer range than Wi-Fi.
• However, WiMAX does not necessarily conflict with Wi-Fi, but is
designed to interoperate with it and may indeed complement it.
• This complementarity to Wi-Fi also extends to all flavors of wired
ethernet (IEEE 802.3), token ring (IEEE 802.5) and non-IEEE standards
that use the same LLC including FDDI and cable modem (DOCSIS).

46. Wi-Max
 WiMAX standard relies mainly on spectrum in the 2 to 11 GHz
range.
 Improves upon many of the limitations of the Wi-Fi standard
– increased bandwidth
– stronger encryption.
 Provides connectivity to network endpoints without direct line of
sight in some circumstances.
 IEEE 802.16 provides up to 50 km (31 miles) of linear service area
range and allows users connectivity without a direct line of sight to a
base station. Note that this should not be taken to mean that users
50 km (31 miles) away without line of sight will have connectivity.
The technology also provides shared data rates up to 70 Mbit/s,
which, according to WiMAX proponents, is enough bandwidth to
simultaneously support more than 60 businesses with T1-type
connectivity and well over a thousand homes at 1Mbit/s DSL-level
connectivity.

47. Wi-Max
 Provides:
• The high speed of broadband service
• Wireless rather than wired access, so it would be a lot less expensive
than cable or DSL and much easier to extend to suburban and rural areas
• Broad coverage like the cell phone network instead of the tiny little
hotspots of WiFi
 WiMAX has the potential to do to broadband Internet access what cell
phones have done to phone access.
 WiMAX could replace cable and DSL services, providing universal Internet
access just about anywhere you go.
 WiMAX will also be as painless as WiFi -- turning your computer on will
automatically connect you to the closest available WiMAX antenna.
 WiMAX would operate similar to WiFi but at higher speeds, over greater
distances and for a greater number of users.

48. Wi-Max  A WiMAX system consists of
two parts:
 A WiMAX tower, similar in
concept to a cell-phone tower
- A single WiMAX tower can
provide coverage to a very
large area -- as big as 3,000
square miles (~8,000 square
km).
 A WiMAX receiver - The
receiver and antenna could be
a small box or PCMCIA card,
or they could be built into a
laptop the way WiFi access is
today.
 Line-of-sight not needed
between user and base station

49. Voice over IP (VoIP)
 method for taking analog audio signals,
like the kind you hear when you talk on
the phone, and turning them into digital data
that can be transmitted over the Internet
or an Ethernet network
 VoIP technology uses the Internet's packet-switching capabilities to
provide phone service
 VoIP can turn a standard Internet connection into a way to place free
phone calls. The practical upshot of this is that by using some of the
free VoIP software that is available to make Internet phone calls, you
are bypassing the phone company (and its charges) entirely.
 has the potential to completely rework the world's phone systems.

50. VoIP – Advantages  VoIP has several advantages over
circuit switching.
 Packet switching allows several
telephone calls to occupy the amount
of space occupied by only one in a
circuit-switched network.
 Using PSTN, that 10-minute phone
call we talked about earlier consumed
10 full minutes of transmission time at
a cost of 128 Kbps.
 With VoIP, that same call may have
occupied only 3.5 minutes of
transmission time at a cost of 64
Kbps, leaving another 64 Kbps free
for that 3.5 minutes, plus an additional
128 Kbps for the remaining 6.5
minutes

51. VoIP – Advantages
 Wider range of features and facilities
 Can provide more information and control about each call
 Can send and receive messages or data files in parallel with the voice
conversation
 audio conferencing
 managing address books and passing presence information about whether
friends/colleagues are available online to interested parties.
 Freer innovation
 Innovation progresses at market rates rather than the slow pace of the
multilateral International Telecommunications Union (ITU) committee
process, resulting in more new advanced features.
 Lower per-call costs
 Once the capital costs of terminals and/or computers and the operating
costs of a data network connection are in place, there are no additional
charges for usage unless the destination is outside the IP network.
 However, this must be offset by the higher costs of telephony equipment.
Services from VoIP providers are not always cheaper than from
conventional telephone service providers.

52. VoIP – Advantages
 Higher quality voice
 higher bandwidth voice encoding can be selected to improve end-to-end
quality.
 However, often high compression techniques are used to save bandwidth
and potentially result in slightly poorer quality than traditional telephony
circuits.
 Lower infrastructure costs
 VoIP reduces the traditional scheme—two separate wiring systems, one
for voice and one for network—to a single connection.
 "Future proof" hardware
Functionality is software (protocol) based, allowing for changes in
software coding without requiring a "forklift" or component upgrade.

53. VoIP – Disadvantages
 Reliability
• Traditional telephones lines carry their own power, service
available during power outages. VoIP depends on regular electric
power service.
• If IP packets are lost or delayed at any point in the network
between VoIP users, there will be a momentary drop-out of
voice.
• More noticeable in highly congested networks and/or where there is
long distances and/or interworking between end points.
• Avoidance of this problem will require introduction of priority
schemes for voice traffic, using Quality of Service mechanisms.
Emergency Calls
The nature of IP makes it difficult to geographically locate
network users
Emergency calls, therefore, can not easily be routed to a nearby
call center, and are impossible on some VoIP systems.

54. VoIP – Disadvantages
 Integration into global telephone number system
– Standard POTS and mobile phone networks share a common global
standard (E.164) which allocates and identifies any specific telephone line
– There is no widely adopted similar standard for VoIP networks.
– There are often different, incompatible schemes when calling between
VoIP providers which use short codes that are provider specific.
• Single point of calling
• In a home PC – based VoIP, it is not possible to share a single line with
three or four telephones.
• New schemes with VoIP compatible cordless phones and routers with
VoIP capability have been introduced.
• Today with commercial services such as Vonage and AT&T CallVantage,
it is possible to connect the VOIP router into the existing central phone
box in the house and have VoIP at every phone already connected.

55. Bluetooth
 Short-range radio frequency technology for wireless personal area networks (PAN)
 Makes it possible to transmit signals over short distances between devices and
thereby simplify communication and synchronization between devices.
 Allows non-line of sight communication
 It is a global standard that:
– eliminates wires and cables between both stationary and mobile devices
– facilitates both data and voice communication
– offers the possibility of ad hoc networks and delivers the ultimate synchronicity
between all your personal devices
 The Bluetooth wireless technology comprises hardware, software and interoperability
requirements.
 Bluetooth radio uses a fast acknowledgement and frequency-hopping scheme to make
the link robust, even in noisy radio environments.

57. Bluetooth
 Bluetooth has been implemented in these devices :
– personal digital assistants (PDAs)
– mobile phones
– Laptops
– PCs, mice, keyboards, printers
– Medical devices
– digital cameras
– Automobiles
– GPS receivers
 Products are available in one of three power classes:
 Class 3 (1 mW) is most common and allows a quoted transmission
distance of 10 m (32 ft)
 Class 2 (2.5 mW) is the rarest and allows transmission of 20 m (64 ft)
 Class 1 (100 mW) has the longest range at up to 100 m (320 ft). This
class of product is readily available.

58. Bluetooth Versions
 Bluetooth 1.0 and 1.0B
– numerous problems with interoperability between vendors
– anonymity almost impossible
 Bluetooth 1.1
– Fixed many bugs from v1.0B
– Added support for non-encrypted channels
 Bluetooth 1.2 : backwards compatible with 1.1
 Adaptive Frequency Hopping (AFH), improves resistance to radio
interference
 Higher transmission speeds in practice
 Extended Synchronous Connections (eSCO), improves voice quality
of audio links
 Received Signal Strength Indicator (RSSI)
 Host Controller Interface (HCI) support for 3-wire UART
 HCI access to timing information for Bluetooth applications.

59. Bluetooth Versions
 Bluetooth 2.0
• Backwards compatible with 1.x.
• The main enhancement is the
introduction of Enhanced Data Rate
(EDR) of 2.1 Mbit/s.
• 3 times faster transmission speed (up
to 10 times in certain cases).
• Lower power consumption through
reduced duty cycle.
• Simplification of multi-link scenarios
due to more available bandwidth.
• Further improved BER (Bit Error
Rate) performance.

60. SMS : Short Message Service
 Wireless service available on digital
mobile networks.
 Enables the transmission of text
messages between mobile phones and
other systems such as electronic mail,
paging and voice mail.
 Up to 160 characters can be sent and
received through the network
operator's message system to the
mobile phone.
 Alternative to paging services
 Can be used to provide reminder
services, stock and currency quotes,
airline schedules, and account
information.
 originally designed as part of the GSM
digital mobile phone standard, but is
now available on a wide range of
networks, including 3G networks

61. EMS : Enhanced Message Service
 Based on SMS (Short Message Service)
 Wireless service available on GSM networks.
 An EMS-enabled mobile phone can receive and send messages that include pixel
pictures and animations, sound effects, ring signals and formatted text.
 Besides the EMS items that are stored in the phone, new items can be received in a
message or downloaded from a WAP site.
 EMS is a widely accepted standard developed by 3GPP.
 EMS items can be exchanged between phones
irrespective of model or make as long as they support
the EMS standard.
 Non-EMS supportive mobile phones treats a message
with EMS items as an SMS text message and only the
text is displayed.
 Cross-industry collaboration between Ericsson,
Motorola, Siemens and Alcatel, among others.

62. x
 x
• x