25-08-2017, 09:32 PM
Wireless Communication Systems
[attachment=27228]
Communication Systems
Provide electronic exchange of multimedia Data, Voice, Video, Music, Email, Web pages, etc.
Communication Systems of today are used for Radio, TV broadcasting, Data and Public Switched Telephone Network (voice, fax, modem)
Cellular Phones
Computer networks (LANs, WANs, and the Internet)
Satellite systems (pagers, voice/data, movie broadcasts)
Bluetooth (Cable replacement)
Wireless Communications
Multimedia wireless Communications at any Time and Anywhere
Brief history
Ancient Systems: Smoke Signals, Carrier Pigeons
Radio invented in the 1880s by Marconi
Many sophisticated military radio systems were developed during and after WW2
Cellular has enjoyed exponential growth since 1988, with more than 2 billion users worldwide today
Ignited the recent wireless revolution, 1980-2003
Current Wireless Systems
Cellular systems
Wireless LANs
Satellite Systems
Paging Systems
Bluetooth
Ultra Wide Band Systems
Zigbee
Cellular Systems: Reuse channels to maximize capacity
Geographic region divided into cells
Frequencies/timeslots/codes reused at spatially-separated
locations.
Co-channel interference between same color cells.
Base stations/MTSOs coordinate handoff and control functions
Shrinking cell size increases capacity, as well as networking burden
Type of Cells
Cell radii can be vary from 10’s of meters in buildings to 100’s of meters in the cities, up to several km’s in the countryside.
Macrocells, provide overall area coverage
Microcells, focus on slow moving subscribers moving between buildings.
Picocells, focus on the halls of a theater, or exhibition centre.
The Wireless Revolution
Cellular is the fastest growing sector of communication
industry (exponential growth since 1982, with over 2 billion users worldwide today)
Three generations of wireless
First Generation (1G): Analog 25 or 30 KHz FM, voice only, mostly vehicular communication
Second Generation (2G): Narrowband TDMA and CDMA, voice and low bit-rate data, portable units.
2.5G increased data transmission capabilities
Third Generation (3G): Wideband TDMA and CDMA, voice and high bit-rate data, portable units
Wireless LAN Standards
802.11b (Current Generation)
Standard for 2.4GHz ISM band (80 MHz)
Frequency hopped spread spectrum
1.6-10 Mbps, 500 ft range
802.11a (Emerging Generation)
Standard for 5GHz NII band (300 MHz)
OFDM with time division
20-70 Mbps, variable range
Similar to HiperLAN in Europe
802.11g (New Standard)
Standard in 2.4 GHz and 5 GHz bands
OFDM
Speeds up to 54 Mbps
Satellite Systems
Cover very large areas
Different orbit heights
GEOs (39000 Km)
LEOs (2000 Km)
Optimized for one-way transmission
Radio (XM, DAB) and movie (SatTV) broadcasting
Most two-way systems struggling or bankrupt
Expensive alternative to terrestrial system
A few ambitious systems on the horizon
Paging Systems
Broad coverage for short messaging
Message broadcast from all base stations
Simple terminals
Optimized for 1-way transmission
Answer-back hard
Overtaken by cellular
Bluetooth
Cable replacement RF technology (low cost)
Short range (10m, extendable to 100m)
2.4 GHz band (crowded)
1 Data (700 Kbps) and 3 voice channels
Widely supported by telecommunications, PC, and consumer electronics companies
Few applications beyond cable replacement
Wireless Comm. Design Challenges
Hardware Design
Precise components
Small, lightweight, low power
Cheap
High frequency operations
System Design
Converting and transferring information
High data rates
Robust to noise and interference
Supports many users
Network Design
Connectivity and high speed
Energy and delay constrains
4G Wireless Communication Systems
Evolution to 4G wireless communication systems
4G: New paradigm shift from technology centric to user centric
4G: Integrated All-IP Architecture
Efficient spectrum sharing concept in 4G wireless networks
Why mobile subscribers are increasing ?
Movement from the Personal Computing Age (one computing device per person) to Ubiquitous Computing Age (several platforms at user’s disposal whenever and wherever needed)
The convergence of media
Numerous demands of multimedia applications arose from huge number of personal wireless devices, which are small, cheap, more convenient and more powerful.
Key Concept of 4G
Global wireless communication system
All-IP based seamless connectivity
4G is foreseen as an integrator of all existing and future wireless and wired networks, both terrestrial and satellite.
4G is not a new system design from scratch but 4G is a concept of integration and convergence
4G systems will deliver
All digital all-IP communication
End-to-end QoS guarantees
Efficient spectrum sharing and dynamic spectrum allocation
Diversified radio access (e.g. cellular, WLAN, ad hoc networks)
Adaptive multimode user terminals (cognitive approach)
Seamless and transparent user roaming with fully support of various handovers.
Support for huge multimedia traffic
Integration of navigation and communication system in order to offer a variety of location/situation/context aware service
Increased level of security
Increased personalization
Quickly deployable user services (anytime, anywhere, and from any device) in cost effective manner
A Definition of Cognitive Radio (CR)
A cognitive radio is an unlicensed communication system
that is aware of its environment
learns from its environment
adapts to the statistical variations of its environment
and uses these to
achieve reliable communication and spectral efficiency by employing spectral holes or opportunities and does not generate harmful interference to the incumbents.
Some Examples
Two examples of star networks with cognitive features:
IEEE 802.16h (WiMAX) provides extensions to support unlicensed co-existence
IEEE 802.22 is an explicit cognitive WRAN that will exploit vacant TV broadcast bands
A little more about IEEE 802.22
IEEE 802.22 has the following interesting characteristics:
Has a complex architecture to detect primary users.
Follows the spectrum overlay approach (avoids interfering with primary users altogether)
Is OFDM based
4G Summary
The 4G paradigm is already on the road.
4G wireless system provide high speed, high capacity, low cost per bits.
4G is IP-based services for broadband multimedia.
Concept of 4G is all about an integrated, global network based on open system approach.
4G wireless systems utilize spectrum efficiently via cognitive approach, and optimize the choice of radio access technology.
Cognitive radio and networking will become the key in reconfigurable wireless system.
[attachment=27228]
Communication Systems
Provide electronic exchange of multimedia Data, Voice, Video, Music, Email, Web pages, etc.
Communication Systems of today are used for Radio, TV broadcasting, Data and Public Switched Telephone Network (voice, fax, modem)
Cellular Phones
Computer networks (LANs, WANs, and the Internet)
Satellite systems (pagers, voice/data, movie broadcasts)
Bluetooth (Cable replacement)
Wireless Communications
Multimedia wireless Communications at any Time and Anywhere
Brief history
Ancient Systems: Smoke Signals, Carrier Pigeons
Radio invented in the 1880s by Marconi
Many sophisticated military radio systems were developed during and after WW2
Cellular has enjoyed exponential growth since 1988, with more than 2 billion users worldwide today
Ignited the recent wireless revolution, 1980-2003
Current Wireless Systems
Cellular systems
Wireless LANs
Satellite Systems
Paging Systems
Bluetooth
Ultra Wide Band Systems
Zigbee
Cellular Systems: Reuse channels to maximize capacity
Geographic region divided into cells
Frequencies/timeslots/codes reused at spatially-separated
locations.
Co-channel interference between same color cells.
Base stations/MTSOs coordinate handoff and control functions
Shrinking cell size increases capacity, as well as networking burden
Type of Cells
Cell radii can be vary from 10’s of meters in buildings to 100’s of meters in the cities, up to several km’s in the countryside.
Macrocells, provide overall area coverage
Microcells, focus on slow moving subscribers moving between buildings.
Picocells, focus on the halls of a theater, or exhibition centre.
The Wireless Revolution
Cellular is the fastest growing sector of communication
industry (exponential growth since 1982, with over 2 billion users worldwide today)
Three generations of wireless
First Generation (1G): Analog 25 or 30 KHz FM, voice only, mostly vehicular communication
Second Generation (2G): Narrowband TDMA and CDMA, voice and low bit-rate data, portable units.
2.5G increased data transmission capabilities
Third Generation (3G): Wideband TDMA and CDMA, voice and high bit-rate data, portable units
Wireless LAN Standards
802.11b (Current Generation)
Standard for 2.4GHz ISM band (80 MHz)
Frequency hopped spread spectrum
1.6-10 Mbps, 500 ft range
802.11a (Emerging Generation)
Standard for 5GHz NII band (300 MHz)
OFDM with time division
20-70 Mbps, variable range
Similar to HiperLAN in Europe
802.11g (New Standard)
Standard in 2.4 GHz and 5 GHz bands
OFDM
Speeds up to 54 Mbps
Satellite Systems
Cover very large areas
Different orbit heights
GEOs (39000 Km)
LEOs (2000 Km)
Optimized for one-way transmission
Radio (XM, DAB) and movie (SatTV) broadcasting
Most two-way systems struggling or bankrupt
Expensive alternative to terrestrial system
A few ambitious systems on the horizon
Paging Systems
Broad coverage for short messaging
Message broadcast from all base stations
Simple terminals
Optimized for 1-way transmission
Answer-back hard
Overtaken by cellular
Bluetooth
Cable replacement RF technology (low cost)
Short range (10m, extendable to 100m)
2.4 GHz band (crowded)
1 Data (700 Kbps) and 3 voice channels
Widely supported by telecommunications, PC, and consumer electronics companies
Few applications beyond cable replacement
Wireless Comm. Design Challenges
Hardware Design
Precise components
Small, lightweight, low power
Cheap
High frequency operations
System Design
Converting and transferring information
High data rates
Robust to noise and interference
Supports many users
Network Design
Connectivity and high speed
Energy and delay constrains
4G Wireless Communication Systems
Evolution to 4G wireless communication systems
4G: New paradigm shift from technology centric to user centric
4G: Integrated All-IP Architecture
Efficient spectrum sharing concept in 4G wireless networks
Why mobile subscribers are increasing ?
Movement from the Personal Computing Age (one computing device per person) to Ubiquitous Computing Age (several platforms at user’s disposal whenever and wherever needed)
The convergence of media
Numerous demands of multimedia applications arose from huge number of personal wireless devices, which are small, cheap, more convenient and more powerful.
Key Concept of 4G
Global wireless communication system
All-IP based seamless connectivity
4G is foreseen as an integrator of all existing and future wireless and wired networks, both terrestrial and satellite.
4G is not a new system design from scratch but 4G is a concept of integration and convergence
4G systems will deliver
All digital all-IP communication
End-to-end QoS guarantees
Efficient spectrum sharing and dynamic spectrum allocation
Diversified radio access (e.g. cellular, WLAN, ad hoc networks)
Adaptive multimode user terminals (cognitive approach)
Seamless and transparent user roaming with fully support of various handovers.
Support for huge multimedia traffic
Integration of navigation and communication system in order to offer a variety of location/situation/context aware service
Increased level of security
Increased personalization
Quickly deployable user services (anytime, anywhere, and from any device) in cost effective manner
A Definition of Cognitive Radio (CR)
A cognitive radio is an unlicensed communication system
that is aware of its environment
learns from its environment
adapts to the statistical variations of its environment
and uses these to
achieve reliable communication and spectral efficiency by employing spectral holes or opportunities and does not generate harmful interference to the incumbents.
Some Examples
Two examples of star networks with cognitive features:
IEEE 802.16h (WiMAX) provides extensions to support unlicensed co-existence
IEEE 802.22 is an explicit cognitive WRAN that will exploit vacant TV broadcast bands
A little more about IEEE 802.22
IEEE 802.22 has the following interesting characteristics:
Has a complex architecture to detect primary users.
Follows the spectrum overlay approach (avoids interfering with primary users altogether)
Is OFDM based
4G Summary
The 4G paradigm is already on the road.
4G wireless system provide high speed, high capacity, low cost per bits.
4G is IP-based services for broadband multimedia.
Concept of 4G is all about an integrated, global network based on open system approach.
4G wireless systems utilize spectrum efficiently via cognitive approach, and optimize the choice of radio access technology.
Cognitive radio and networking will become the key in reconfigurable wireless system.