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1. Module
II
WIRELESS
NETWORKING

2. MODULE II
 Satellite Communications
 Satellite Parameters and Configurations
 Capacity Allocation – Frequency Division
 Capacity allocation time division
 Wireless System Operations and Standards
 Cordless systems 2.2.2
 Wireless Local Loop 2.2.3
 IEEE 802.16 Broadband wireless access standards
 Mobile IP and WAP
 Operation of Mobile-IP
 architectural overview of Wireless Application Protocol

3.  Satellite Communication
 Satellite Parameters and configurations
 Satellite Orbits
 Frequency Bands
 Transmission Impairments
 Satellite Network Configurations
 Capacity Allocation – Frequency Division
 FDM (Frequency Division Multiplexing)
 FDMA (Frequency Division Multiple Access)
 Capacity allocation time division

4. Satellite systems
 Satellite communication introduces another
system supporting mobile communications.
A satellite is a body that moves around another body in
a particular path called orbit.
GEO
MEO LEO

5. Satellite systems
If the communication takes place between any two earth
stations through a satellite, then it is called as satellite
communication.
In this communication, radio waves used for satellite
communications & electromagnetic waves are used as
carrier signals.
These signals carry the information such as voice, audio,
video or any other data between ground and space and vice-
versa.
Satellites offer global coverage without wiring cost for
base stations

7. Applications
Satelite are specifically made for telecommunication
network
 Weather forecasting:
Several satellites deliver pictures of the earth using
infra red or visible light.
 Radio and TV broadcast satellites:
 Hundreds of radio and TV programs are available
via satellite.
 Military satellites:
 For carrying out espionage
 Satellites for navigation: Identify ground
position of an object using GPS


8.  Global telephone backbones
For the establishment of international
telephone backbones.
 Connectionsfor remote or developing
areas
 Global mobile communication
The latest trend for satellites is the support of
global mobile data communication such as ship
,plane ,car etc

10. Advantages
* Point to multipoint communication is possible.
* Area of coverage is more than that of terrestrial systems
* Each and every corner of the earth can be covered
* Transmission cost is independent of coverage area
* More bandwidth and broadcasting possibilites.
*24 hr communication is possible.
Disadvantages
*Initial expenditure is high
*Propagation delay of satellite systems is more than that of conventional terrestrial
systems.
*Difficult to provide repairing activities if any problem occurs in a satellite system.
*Free space loss is more
*There can be congestion of frequencies.

11. Basics of satellite systems
1)Satellites orbit around the earth,it can be circular or elliptical.
 2)Satellites in circular orbits always keep the
same distance to the earth’s surface
3)To keep the satellite in a stable circular orbit by maintaining
attractive force and centrifugal force equal
Factors affecting performance of satellite are
1 Distance
2. Satellite footprint(coverage )
3. Atmospheric attenuation

12. Satellite-Elements
 Relay Station - Two or more stations on or near the
earth communicate via one or
more satellites in space
 Earth Station - Antenna systems on or near earth
 Uplink
 Downlink
- Transmission from an earth station to a
satellite
- Transmission from a satellite to an earth
station
-
 Transponder- Electronics/component in the satellite
that convert uplink signals to downlink
signals

13. Ways to Categorize Communications
Satellites
 Coverage area
 Global, regional, national
 Service type
 Fixed service satellite (FSS)
 Broadcast service satellite (BSS)
 Mobile service satellite (MSS)
 General usage
 Commercial, military, amateur, experimental

14. Differences with Terrestrial Wireless
Communications - Design Parameters
 The area of coverage of a satellite system far exceeds that
of a terrestrial system.
 Conditions between communicating satellites are more
time invariant than those between satellite and earth
station, or between 2 terrestrial wireless antennas.
 Within the satellite’s area of coverage, transmission cost
is independent of distance.

15. Differences …..
 Broadcast, multicast and point-to-point applications are
readily accommodated.
 Availability of very high bandwidths and data rates.
 The quality of transmission is extremely high in
satellite links, even though they are subject to short-
term outages or degradations.
 For a geostationary satellite, the earth-satellite-earth
propagation delay is about one-fourth of a second
 A transmitting earth station can in many cases receive
its own transmission

16. Classification of Satellite Orbits
 1)By shape
 Circular or elliptical orbit
 Circular with center at earth’s center
 Elliptical with one foci at earth’s center
 2)By inclination
 Orbit around earth in different planes
 Equatorial orbit above earth’s equator
 Polar orbit passes over both poles
 Other orbits referred to as inclined orbits
 3) ByAltitude of satellites
 Geostationary orbit (GEO)
 Medium earth orbit (MEO)
 Low earth orbit (LEO)

17. Geometry in Satellite coverage area
 Orbit Height (h)
 Coverage Angle (β)
Elevation Angle (θ)

18. Geometry terms……
 Elevation angle
The angle between the vertical plane and line pointing
to satellite is known as Elevation angle.
 Minimum (00)elevation angle, obtain maximum
coverage
 Uplink (min 50)
 Downlink (50 – 200)

19. Elevation angle…..
 Three Problems occured when minimum
elevation angle >0 degree .
 Objects Blocking the LOS
 Atmospheric attenuation is greater at low
elevation angles
 Electrical noise generated by earth heat near the
surface affects reception.

20.  Coverage Angle ()
 Measure of the portion of the earth's surface visible to
the satellite
 Defines a circle in the surface of the earth centered on
the point directly below the satellite.
 Area of coverage can be calculated.
 Area of coverage expressed as the diameter of
the area covered = 2 βR, R – radius of the
earth 6370km, β expressed in radians

21. c
 Distance from Satellite to Earth
d 
(R  h)sin()
cos()

22. Types of orbits
Altitude based
Geostationary (or
geosynchronous) earth orbit
(GEO): GEO
Medium earth orbit (MEO)
Low earth orbit (LEO)
Highly elliptical orbit (HEO)

23. Geostationary (or geosynchronous)
Earth Orbit (GEO)
 Most common type of communications satellite.
 The satellite is in a circular orbit of 35,863 km
above the earth's surface
 It rotates in the equatorial plane of the earth
 It will rotate at exactly the same angular speed as the
earth.
 It will remain above the same spot on the equator as
the earth rotates.

24. GE
O
 It appears to be in a fixed position to an earth-
based observer
 It revolves around the earth at a constant
speed once per day over the equator
 Examples:
 almost all TV and radio broadcastsatellites,
 many weather satellites
 satellites operatingas backbones for the
telephone network.

26. Geostationary orbits

28. Advantages
 No problem with frequency changes
 Tracking of the satellite is simplified
 High coverage area
 Three GEO satellites are enough for a complete coverage of
almost any spot on earth and separated by 1200
 Senders and receivers can use fixed antenna positions, no
adjusting is needed.
 GEOs are ideal for TV and radio broadcasting.
 GEOs typically do not need a handover due to the large
footprint.

29. Disadvantage
s
 Weak signal after traveling over 35,000 km
 Polar regions on both hemispheres are poorly
served
 Signal sending delay is substantial (0.24s)
 Northern or southern regions of the earth have more
problems receiving these satellites due to the low
elevationabove a latitude of 60°
 The transmit power needed is relatively high

30. Low earth orbit (LEO) Satellites
 Circular/slightly elliptical orbit under 2000 km
 The diameter of coverage is about 8000 Km.
 Orbit period ranges from 1.5 to 2 hours
 Round-trip signal propagation delay less than 20
ms
 Maximum satellite visible time up to 20 min
 Atmospheric drag results in orbital deterioration

31. LEO
 Satellitesin low earth orbit change their position
relative to the ground position quickly.
 LEO satellites were mainly used for espionage.
 Satellite on this class use altitudes of 500–1,500 km.
 These are less expensive to launch into orbit

33. LEOs – Advantages over GEOs
 Reduced propagation delay
 Received signal is much stronger than that of a
GEO for the same transmissionpower
 Coverage can be better localized, so that
spectrum can be better conserved.
 It provide broad coverage over 24 hours

34. LEO Categories
Little LEOs
 Frequency below 1 GHz
 5MHz of bandwidth
 Data rates of up to 10 kbps
 Aimed at paging, tracking and low rate
messaging
 Example : Orbcomm - first little LEO in
operation

35. LEO Categories
Big LEOs
 Frequencies Above 1 GHz
 Support data rates up to a few megabits per
sec
 Offer same services as little LEOs in
addition to voice and positioning services
 Example : Globalstar

36. Medium earth orbit (MEO)Satellites
 Circular orbit at an altitude in the range 5000 to 12000
Km.
 The orbit period is about 6 hours
 The diameter of coverage is from 10000 to 15000 Km.
 Round trip signal propagation delay is less than 50 ms.
 The maximum time that the satellite is visible from a fixed
point on earth (above the radio horizon) is a few hours
 MEOs can be positioned somewhere between LEOs
and
GEOs
 Applications are digital voice, data, facsimile, high-
penetration notification, and messaging services

40. FrequencyBand
 Two frequencies are necessary for satellite
communication– uplink(transmitting signal to
satellite) and downlink frequency(receiving
signals from satellite)
 Reserved for satellite communication
 Divided in several bands such as L, S, Ku, etc in
gigahertz (microwave) frequency range
 Higher the frequency, higher is the bandwidth.

41. Frequency Bands Available for Satellite
Communications
Band Frequency
Range
Total
Bandwidt
h
General Application
L 1 to 2 GHz 1 GHz Mobile satellite service (MSS)
S 2 to 4 GHz 2 GHz MSS, NASA, deep space research
C 4 to 8 GHz 4 GHz Fixed satellite service (FSS)
X 8 to 12.5 GHz 4.5 GHz FSS military, terrestrial earth
exploration, meteorological
satellites
Ku 12.5 to 18
GHz
5.5 GHz FSS, broadcast satellite service
(BSS)
K 18 to 26.5 GHz 8.5 GHz BSS, FSS
Ka 26.5 to 40
GHz
13.5 GHz FSS

42. Transmission Impairments
 The performance of a satellite link depends on :
 Distance between earth and satellite
 Atmospheric Attenuation
 Affected by oxygen, water, angle of elevation, and higher
frequencies
 Terrestrial Distance between the receiving antenna and
the aim point of the satellite (Satellite Footprint)
 Footprint is defined as the area on the earth where the
signal of the satellite can be received

43. Satellite Network Configurations
 Point to Point
 Broadcast

44. Subscribers use low cost VSAT (very small aperture terminal
) antenna.
Stations share a satellite transmission capacity for
transmission to a hub station
• Hub can exchange messages with the subscribers and relay
messages between the subscribers

45. Capacity Allocation Strategies



 Frequency division multiple access (FDMA)

 Time division multiple access (TDMA)

 Code division multiple access (CDMA)

46. Capacity Allocation –
Frequency Division
 A GEO satellite will handle large bandwidth (500 MHz)
 Divide the bandwidth into a number of channels of
smaller (e.g., 40 MHz).
 Within each channels, capacity allocation task is to be
performed.
 In some cases, the entire channel is dedicated to a
single user or application.
 The use of the satellite requires that each channel be
shared by many users.
 Hence, the task is fundamentally one of multiplexing.

47. Frequency-Division Multiplexing
 the overall capacity of a communications satellite is
divided into a number of channels. This is a top level
of FDM
 Further capacity allocation is carried out within each
channel.

48. FDM
 FDM scheme for GEO communications satellites is
used in the Galaxy satellites from PanAmSat.
 Uses C band frequencies and provides 500-MHz
bandwidth, which is broken up into 24 40-MHz
channels.
 Each frequency assignment is carried by two
carriers with orthogonal polarization.
 Each 40-MHz channel includes a 4-MHz
guardband, so each channel is actually 36 Mhz
wide

49. FDMA
 A single frequency channel is to be divided
into a number of smaller channels using FDM.
 Each uses FM.
 Each of the smaller channels carries a number
of voice frequency (VF) signals using FDM.
 The ability of multiple earth stations to access
the same channel is referred to as FDMA.

50. FDMA
 Factors that limit the number of
subchannels in satellite communication
usingFDMA is
 Thermal noise
 Noise is generated by thermal agitation of electrons
 Intermodulation noise
 In transmission path noise generated by modulation
and demodulation
 Crosstalk
 A disturbance, caused by electromagnetic
interference.

51. Types of FDMA
 Fixed-assignment multiple access (FAMA)
 capacity is distributed in a fixed manner among
multiple stations
 Underuse of capacity due to fluctuations in demand
 Demand-assignment multiple access (DAMA)
 Capacity assignment is changed as needed to demand
changes among the multiple stations

52. Capacity Allocation - TDMA
 TDMA (Time Division Multiple Access)
 Breaks a transmission into multiple time slots,
each one dedicated to a different transmitter.
 TDMA is increasingly becoming more widespread
in satellite communication.
 TDMA uses the same techniques (FAMA and
DAMA)

53. TDMA (cont.)
 Advantages of TDMA over FDMA.
 Digital equipment used in time division
multiplexing is increasingly becoming
cheaper.
Advantages of digital components:
 Ex: error correction.
 Lack of intermodulation noise

54. FAMA-TDMA Operation
 Transmission in the form of repetitive sequence of
Frames
 Each frame is divided into a number of time slots„
 Each slot is dedicated to a particular transmitter
 Earth stations take turns using uplink channel
 Sends data in assigned time slot
 Satellite repeats incoming transmissions
 „ Broadcast to all stations
„Stations must know which slot to use for
transmission and which to use for reception

55. Cordless Systems and
Wireless Local Loop
Technologies to bring wireless access into
Residence and office

56. CORDLESS SYSTEMS
 It evolved from cordless telephone technology.
 It provide users with mobility within an area with
an analog wireless link.
 Later digital cordless telephones were
developed
 Cordless systems can support multiple users from
the same base station.
 It operate in a number of environments.

57. Cordless System Operating Environments
Residential:
 Within a residence a single base station can
provide voice and data support
 Office:
 A single base station can support a small office.
 Multiple base stations in a cellular configuration support a
large office
 Telepoint:
 A base station set up in a public place.
 Eg: airport, shopping mall etc

58. Design Considerations
for Cordless Standards
 Modest range of base station (about 200m),
 so low-power designs are used.
 Inexpensive handset and base stations
 By simple technical approaches in
 speech coding
 channel equalization.
 Frequency flexibility is limited, because the system
needs to be able to seek a low-interference
channel.

59. Standards for Cordless Systems
 1)DECT- Digital Enhanced Cordless
Telecommunications
 Developed in Europe
 2)PWT (Personal Wireless
Telecommunication)
 Developed in U S
 Both works on the basis of TDD (Time
Division Duplex)

60. Time Division Duplex
 Also known as time-compression multiplexing (TCM)
 Data are transmitted in one direction at a time,
with transmission alternating between the two
directions.
 Two types
 Simple TDD
 TDMA/TDD

61. Simple TDD
 Bit stream is divided into equal segments
 Compressed in time to ahigher transmission rate
and transmitted in bursts.
 The data segments are expanded at the other
end to the original rate.
 The actual data rate on the channel must be
greater than twice the data rate required by the
two end systems

63. TDMA TDD
 Wireless TDD is used with TDMA
 Number of users receive forward (base to handset)
channel signals and then transmit reverse (handset
to base) channel signals in turn.
 All on the same carrier frequency.
 Advantages:
 Improved ability to cope with fast fading
 Improved capacity allocation.

64. Wireless Local Loop
 The circuit between the subscriber’s equipment and the
local exchange is called the local loop
 Wired technologies responding to the need for reliable,
high-speed access by residential, business, and
government subscribers like ISDN, xDSL, cable modems „
 Increasing interest shown in competing wireless
technologies for subscriber access
The function of a WLL is to make primary access to local
telephone station using wireless link.It is based on
cellullar statllite. The standard for WLL is known as
IEEE802.16.

65. Wireless Local Loop (WLL)

A WLL provider services one or more cells. Each cell includes a
base station antenna, mounted on top of a tall building or
tower. Individual subscribers have a fixed antenna mounted on
a building or pole that has an unobstructed line of sight to the
base station antenna.
From the base station, there is a link, which may either be wired or
wireless, to a switching center..The switching center is typically
a telephone company local office, which provides connections
to the local and long-distance telephone networks.An Internet
service provider (ISP) may be connected to the switch by a
high-speed link..

66. Concepts of WLL
 Narrowband WLL – offers a replacement for
existing telephony services.
 Broadband WLL – provides high-speed two-
way voice and data service.
 Thus, WLL is the best system to handle high
data traffic in the local loop system.

67. WLL Configuration/Role of WLL

68. Advantages of WLL over Wired
Approach
 Cost – Wireless systems are less expensive
 Installation time – WLL systems can be installed in
a small fraction of the time required for a new
wired system
 Selective installation – radio units installed for
subscribers who want service at a given time
 With a wired system, cable is laid out in
anticipation of serving every subscriber in a given
area

69. IEEE 802.16 Broadband wireless Access
Standards
 In 1999, the IEEE 802 committee set up the 802.16
working group to develop broadband wireless
standards.
 An industry group, the WiMAX (Worldwide
Interoperability for Microwave Access) Forum,
has been formed to promote the 802.16 standards
 A standards-based technology enabling the
delivery of wireless broadband access
 It is one of the hottest broadband wireless
technology around today.

70. IEEE 802.16
 This systems are expected to deliver wireless broadband
access services to residential and enterprise customers in
an economical way.
 Use wireless links with microwave or millimeter wave
radios(10GHz-300GHz)
 Use licensed spectrum
 Provide public network service to fee-paying customers.
 Use point-to-multipoint architecture with stationary
rooftop or tower-mounted antennas
 Provide efficient transport of heterogeneous traffic
supporting quality of service (QoS)
Are capable of broadband transmissions (>2 Mbps)

71. Features
 Higher connection speed than Wi-Fi(LAN))
 Wider area coverage( called as MAN)
 High data rates with orthogonal frequency Division Multiplexing(OFDM)ie
,it is a method of data transmission where a single information stream is split among several
closely spaced narrowband subchannel frequencies instead of single wideband channel frequency
 Less time to install
 Supports wider range in low cost
Quality of Service

72. Bearer Services/data services
1.Digital audio/video multicast : Transport one-way
digital audio/video streams to subscribers.
2. Digital telephony
3.ATM network
4. Internet Protocol :Support transfer of IP
datagrams,Efficinet timely service
5.Bridged LAN: Transfer of data between two LAN’s
6.Back-haul:Provide wireless trunks for wireless telephony
base stations.
7. Frame relay: Similar to ATM Frame relay,support
variable length frame relays

73. Protocol Architecture
physical layer
 Encoding/decoding of signals
 • Preamble generation/removal (for
synchronization)
 • Bit transmission/reception

74. Transmission layer
 On transmission, assemble data into a frame with
address and error detection fields.
 On reception, disassemble frame, and perform
address recognition and error detection.
 Govern access to the wireless transmission
medium.

75. Medium Access Control Layer
 It is responsible for sharing access to the radio channel
between the base station and the subscriber station.
 MAC protocol defines how and when a base station or
subscriber station may initiate transmission on the
channel.
 MAC protocol must be able to allocate radio channel
capacity to satisfy service demands.
 MAC protocol is relatively simple in downstream and
more complex in upstream

76. Convergence layer
 Encapsulate PDU (protocol data unit) framing of
upper layers into the native 802.16 MAC/PHY
frames.
 Map an upper layer's addresses into 802.16
addresses.
 Translate upper layer QoS parameters into native
802.16 MAC format.
 It also provide multimedia,atm and telphone
services.

77. Applications of WiMAX
 Residential or Home and Broadband Internet
Access
 Medium and small size business
 Backhaul networks for cellular base stations:
 WiFi Hotspots.

78.  802.16.1 (10-66 GHz, line-of-sight, up to 134Mbit/s)
 802.16.2 (minimizing interference between coexisting
WMANs)
 802.16a (2-11 Ghz, Mesh, non-line-of-sight)
 802.16b (5-6 Ghz)
 802.16c (detailed system profiles)
 P802.16e (Mobile Wireless MAN)
IEEE 802.16 standards

79. Mobile IP
 Mobile IP was developed to enable computers to maintain
Internet connectivity while moving from one Internet
attachment point to another without changing their actual ip
 Mobile IP can work with wired connections also.
 In wired connection computer is unplugged from one physical
attachment point and plugged into another.
 The user's point of attachment changes dynamically, and all
connections are automatically maintained
 This temporary IP address is used by the user's correspondent
for each application-level connection (e.g., FTP, Web
connection).

80. Operation of Mobile IP
 A mobile node is assigned to a particular network, known
as its home network
 Its IP address on home network known as its home
address, and is static
 When the mobile node moves its attachment point to
another network, that network is considered as a foreign
network(any network other than home network)
 Once the mobile node is reattached, it makes its presence
by registering with a network node, typically a router, on
the foreign network known as foreign agent.

81.  The mobile node communicates with a similar agent on the
user's home network is Home Agent
 The foreign host then contacts the user's home agent and
gives it a care-of address, normally the foreign agent's own
IP address
 The care-of address identifies the foreign agent's location.

82. Mobile

83. Capabilities of Mobile IP
 Discovery – A mobile node uses a discovery procedure to
identify prospective home agents and foreign agent
 Registration – A mobile node uses an authenticated
registration procedure to inform its home agent of its care
of address
 Tunneling – Is used to forward IP datagrams from a home
address to a care-of address

84. Wireless Application Protocol (WAP)
 Wireless Application Protocol (WAP) is a technical
standard for accessing information over a mobile
wireless network.
 A WAP browser is a web browser for mobile
devices such as mobile phones that uses the
protocol.

86. WAP is
 An application communication protocol
 It is used to access services and information
 It is for hand held devices
 It enables creating of web applications for mobile
devices
 WAP uses mark-up language(WML)

87.  WAP is the set of rules governing the transmission
and reception of data by computer applications on
a wireless devices like mobile phones.
 WAP allows wireless devices to view specifically
designed pages from the Internet, using only plain
text and very simple black-and-white pictures.
 WAP is a standardized technology for cross
platform, distributed computing.

88. It is optimized for:
 Low-display capability
 Low-memory
 Low-bandwidth devices, such as personal digital
assistants (PDAs), wireless phones, and pagers.

89. WAP Advantages
 Implementation near to the Internet model
 Most modern mobile telephone devices support WAP
 Real-time send/receive data
 Easy, and fast access to Internet.
 WML and WMLScript (new language, which is based on HTML).
 Large choice in mobile phones
 Can be used to download abstract data types ( Eg:videos)
 Supports most wireless networks (like: CDMA, GSM,
PDC(personnal digital cellular), PHS(personal handyphone
system), TDMA etc.).
 Can be built on any operating system.
 Open standard and vendor independent.

90. Disadvantages
 Low speed, security, and very small user interface
 Not very familiar to the users
 Business model is expensive
 Forms are hard to design

91. WAP Architecture

92. Application Layer
This layer contains the Wireless Application Environment (WAE). It contains
mobile device specifications and content development programming languages
like WML.
Session Layer: This layer contains Wireless Session Protocol (WSP). It
provides fast connection suspension and reconnection.
Transaction Layer: This layer contains Wireless Transaction Protocol (WTP). It
runs on top of UDP (User Datagram Protocol) and is a part of TCP/IP and offers
transaction support.
Security Layer:
This layer contains Wireless Transaction Layer Security (WTLS). It offers data
integrity, privacy and authentication.
Transport Layer:
This layer contains Wireless Datagram Protocol. It presents consistent data
format to higher layers of WAP protocol stack.