Bikash Sadhukhan. M.Tech(CSE)
Lecturer. Dept of CSE/IT
Techno India College of Technology
Mobile Communication
� Entails transmission of data to and from handheld
devices
� Two or more communicating devices
� At least one is handheld or mobile� At least one is handheld or mobile
� Location of the device can vary either locally or
globally
� Communication takes place through a wireless,
distributed, or diversified network
Brief history of Wireless communication
� 1901 Marconi’s first demonstration of transatlantic wireless
communication using electromagnetic waves
� 1907 onwards commercial transatlantic communication
� 1920 discovery of short waves by Marconi
� 1928 many TV broadcast trials
� 1950s-1970s --- Some commercial installations of fixed wireless � 1950s-1970s --- Some commercial installations of fixed wireless
telephony, e.g., A-Netz and Bnertz systems in Germany
� 1970 ALOHANET: first packet radio network (University of Hawaii)
� 1979 Nordic Mobile Telephony (NMT) system
� 1981 start of Global Spéciale Mobile (GSM) specification
� 1982 start of American Advanced Mobile Phone System (AMPS)
specification
� 1984 CT-1 standard (Europe) for cordless telephones
� 1991 Digital European Cordless Telephony (DECT)
Brief history of Wireless communication� 1992 Start of GSM
� 1996 High Performance Radio Local Area Network (HiperLAN)
� 1997 wireless LAN standard IEEE802.11 released
� 1998 specification of the Universal Mobile Telecommunication System
(UMTS) as European proposal for IMT-2000
� 1999 new wireless LAN standards – 802.11b and 802.11a
� 1999 first specification of Bluetooth
� 2000 GSM with higher data rates and first GPRS trials
� 2001 start of third generation (3G) systems
� 2001 specification of the fixed wireless broadband standard IEEE 802.16
(WiMax) released
� 2003 Improved version IEEE 802.16a released
� 2003 IEEE802.11g released
� 2003 IEEE 802.15.4 standard released (which eventually led to the
development of the ZigBee application stack)
Guided Transmission
� Metal wires and optical fibres guided or wired
transmission of data
� Guided transmission of electrical signals takes
place using four types of cables
� Fibre- and wire- based transmission and their � Fibre- and wire- based transmission and their
ranges:
Four types of cables for Guided
Transmission
1. Optical fibre for pulses of wavelength 1.35–1.5 µm
2. Coaxial cable for electrical signals of frequencies up
to 500 MHz and up to a range of about 40 m
3. Twisted wire pairs ─ for conventional (without
coding) electrical signals of up to 100 kHz and up to a coding) electrical signals of up to 100 kHz and up to a
range of 2 km, or for coded signals of frequencies up to
200 MHz and a range of about 100 m
4. Power lines, a relatively recent advent in
communication technology─ used for long-range
transmission of frequencies between 10 kHz and 525
kHz
Guided Transmission Advantages
� Transmission along a directed path from one point to
another
� Practically no interference in transmission from any
external source or path
� Using multiplexing and coding, a large number of
signal-sources simultaneously transmitted along an
optical fibre, a coaxial cable, or a twisted-pair cable
Guided Transmission Disadvantages
� Signal transmitter and receiver fixed (immobile).
� No mobility of transmission and reception points.
� Number of transmitter and receiver systems limits
the total number of interconnections possiblethe total number of interconnections possible
Unguided─ Wireless Transmission
� Electrical signals transmitted by converting them
into electromagnetic radiation
� Radiation transmitted via antennae that radiate
electromagnetic signalselectromagnetic signals
� Various frequency bands within the
electromagnetic spectrum
� Different transmission requirements
� f = c/λ = (300/ λ)MHz [λ in meter]
Classification of wireless networks
Wireless personal area network (WPAN)
� Network between devices carried by a person
Examples
� Interconnection between a mobile phone and a headset
� Interconnection between a laptop and projector
equipmentequipment
� Wearable computing: everything from helmets,
sunglasses to clothes
Technologies
� InfraRed (IrDA)
� IEEE 802.15 radio standards
Wireless local area network (WLAN)
� Network between devices in home and office
environment; typically gives access to a fixed
infrastructure
� Examples:
� Interconnection of stationary and mobile devices such as
desktops, laptops, telephones, television, etc.desktops, laptops, telephones, television, etc.
� Internet access at public venues such as airports,
restaurants, conferences, etc.
� Technologies
� IEEE 802.11 radio standards (WiFi)
� Digital Enhanced Cordless Telephony (DECT)
Wireless metropolitan area network
(WMAN)
Wireless Wide area networks (WWAN)
Range vs. data rate
Wireless transmission fundamentals
Frequency spectrum
Radio propagation
� Signals and antennasSignals and antennas
� Modulation
� Channel conditions
� Effects of mobility
Multiple access
Medium access control
Frequencies for communication
Frequencies for communication
Orderly use of frequency spectra reduces interference
� International Telecommunications Union (ITU) for worldwide
coordination
� Federal Communications Commission (FCC) in the US
� European Conference for Posts and Telecommunications (CEPT) and
European Telecommunication Standards Institute (ETSI) in EuropeEuropean Telecommunication Standards Institute (ETSI) in Europe
� License spectrum is allocated for proprietary use, e.g., cellular
communication
� Unlicensed spectrum is available for general use (with restrictions),
e.g., 2.4 GHz ISM band
Mobile devices
Effects of device portability
Wireless networks in comparison to
fixed networks
Simple reference model used here
Influence of mobile communication
to the layer model
Development of mobile communication
systems
First and Second Generations (1G & 2G)
� First generation wireless devices only voice signals
� Second generation (2G) devices communicate voice as
well as data signals have data rates of up to 14.4 kbps
� The 2.5G and 2.5G+ are enhancements of the second � The 2.5G and 2.5G+ are enhancements of the second
generation and support data rates up to 100 kbps
Third generation (3G) mobile devices
communication
� Higher data rates than 2G and support voice, data,
and multimedia streams
� Facilitates data rates of 2 Mbps� Facilitates data rates of 2 Mbps
� Data rates are higher for short distances and 384 kbps
for long distance transmissions
� Enable transfer of video clips and faster multimedia
communication
AMPS
� AMPS is an analog cellular phone system using
FDMA.
� Invented by Bell Labs and first installed in the United
States in 1982. It was also used in EnglandStates in 1982. It was also used in England
D-AMPS
� The second generation of the AMPS systems is D-
AMPS and is fully digital.
� D-AMPS was carefully designed to co-exist with � D-AMPS was carefully designed to co-exist with
AMPS so that both first- and second-generation
mobile phones could operate simultaneously in the
same cell.
GSM - Global System for Mobile
CommunicationGSM offers
� several types of connections� voice connections, data connections, short message service
� multi-service options (combination of basic services)
Three service domains:
� Bearer Services: � Bearer Services: � Telecommunication services to transfer data between access points
� data service (circuit switched)� synchronous: 2.4, 4.8 or 9.6 kbit/s
� asynchronous: 300 -1200 bit/s
� data service (packet switched)� synchronous: 2.4, 4.8 or 9.6 kbit/s
� asynchronous: 300 -9600 bit/s
GSM service domains
� Telematic Service
� Telecommunication services that enable voice communication via mobile phones
� Offered services
� Mobile telephony: Primary goal of GSM was to enable mobile telephony offering the traditional bandwidth of 3.1 kHz telephony offering the traditional bandwidth of 3.1 kHz
� Emergency number: Common number throughout Europe (112); mandatory for all service providers; free of charge; connection with the highest priority (preemption of other connections possible)
� Voice mailbox (implemented in the fixed network supporting the mobile terminals)
� Electronic mail (MHS - Message Handling System, implemented in the fixed network)
� Short Message Service (SMS)
GSM service domains
� Supplementary Services
� Services in addition to the basic services, cannot be
offered stand-alone
� Similar to ISDN services besides lower bandwidth due to
the radio link
May differ between different service providers, countries � May differ between different service providers, countries
and protocol versions
� Important services
� identification: forwarding of caller number
� suppression of number forwarding
� automatic call-back
� conferencing with up to 7 participants
� locking of the mobile terminal (incoming or outgoing calls)
Performance characteristics of GSM� Communication
- mobile, wireless communication; support for voice and data services
� Total mobility
- international access, chip-card enables use of access points of different
providers
� Worldwide connectivity
- one number, the network handles localization- one number, the network handles localization
� High capacity
- better frequency efficiency, smaller cells, more customers per cell
� High transmission quality
- high audio quality and reliability for wireless, uninterrupted phone calls
at higher speeds (e.g., from cars, trains)
� Security functions
- access control, authentication via chip-card and PIN
GPRS -General Packet Radio Service
� A packet-oriented service for mobile stations’ data transmission and their access to the Internet
� A speed enhanced data transmission service designed for GSM systems
� Speed enhanced data transmission─ by packetizing data and simultaneous transmission of packets over different channelsdata and simultaneous transmission of packets over different channels
� Uses the unused slots and channels in TDMA mode of a GSM network for packetized transmission from a mobile station
� Data-packets of a single mobile station transmit through a number of time slots
� Advantage: one step towards UMTS, more flexible
� Disadvantage:more investment needed (new hardware)
EDGE (Enhanced Data rates for GSM
Evolution)
� EDGE is a more advanced upgrade tod the GSM
standard and requires the addition of new
hardware and software at existing base stations.
� 8 PSK communication to achieve higher rates of � 8 PSK communication to achieve higher rates of
up to 48 kbps per 200 kHz channel
� High date rates compares to up to 14.4 kbps in
GSM.
� Using coding techniques the rate can be enhanced
to 384 kbps for the same 200 kHz channel
CDMA (Code Division Multiple Access) � CDMA supports high data rates
� Initial evolution of CDMA was 2.5 G. But Nowadays CDMA supports high data
rates and considered as 3G.
� Voice as well as data and multimedia streams.
� CDMA more robust for multi-path delays and provides higher immunity towards
frequency selective fading
� Each mobile station’s or base transceiver’s signals are coded with two or three
codes
� Signals of higher voice and data quality and small bit-error rates
� Soft handover- Soft handover means that an MS at the boundary of two adjacent
cells does not have to drop calls due to signal break during handover at the
boundary region
� CDMA systems provide seamless connectivity to the MS
� CDMA systems perform power control by open loop or close loop methods to solve
the problem of drowning of signals from far mobile terminals by those from the
near terminals
� CDMA systems employ spread spectrum techniques (DSSS and FHSS) for medium
access control thus problems in narrow band transmission not present
UMTS (Universal mobile
telecommunication system)
� Communicates at data rates of 100 kbps to 2 Mbps
� It combines CDMA for bandwidth efficiency and
GSM for compatibility.
� It support several technologies for transmission � It support several technologies for transmission
and gives a framework for security and
management functions.
Comparison of GSM and CDMA
Mobile computing─ A Definition
� The process of computation on a mobile device
� In mobile computing, a set of distributed
computing systems or service provider servers
participate, connect, and synchronize through participate, connect, and synchronize through
mobile communication protocols
� Mobile computing as a generic term describing
ability to use the technology to wirelessly connect
to and use centrally located information and/or
application software through the application of
small, portable, and wireless computing and
communication devices
Mobile computing
� Provides decentralized (distributed) computations
on diversified devices, systems, and networks,
which are mobile, synchronized, and
interconnected via mobile communication interconnected via mobile communication
standards and protocols.
� Mobile device does not restrict itself to just one
application, such as, voice communication
� Offers mobility with computing power
� Facilitates a large number of applications on a
single device
Limitations to mobile computing� Resource constraints: Battery
� Interference: the quality of service (QoS)
� Bandwidth: connection latency
� Dynamic changes in communication environment: � Dynamic changes in communication environment:
variations in signal power within a region, thus link
delays and connection losses
� Network Issues: discovery of the connection-service to
destination and connection stability
� Interoperability issues: the varying protocol standards
� Security constraints: Protocols conserving privacy of
communication
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