Advanced Topics in Next-Generation Wireless Networks
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Transcript of Advanced Topics in Next-Generation Wireless Networks
Advanced Topics in Next-Generation Wireless Networks
Qian ZhangDepartment of Computer Science
HKUST
Introduction of Wireless Networks
Why Wireless?
• Convenience and flexible
• Mobility
• Coverage
• Easy to deploy
• Low cost
• New applications potential
• Improved quality of life (people with disabilities)
anytime
anywhere
any device
service
4A: Anytime, Anywhere, Any device, and Any service
Fast Growing Devices Create New Connectivity Demands
Wireless Technologies
WWAN (3G,4G?)
WLAN (Wi-Fi)
WPAN
WMAN (Wi-Max)
BluetoothUWBRFID
coverage
Big Picture – WPAN’s
• WPAN technologies – RFID, Bluetooth, UWB• RFID used in tagging applications, restricted
environments (supermarkets, institutions)• 10 billion RFID tags been sold by the end of 2005
(source: Deloitte & Touche)
• Bluetooth – technology has matured • 56% of mainstream devices commercialised will
have Bluetooth support by 2008 (Source: IDC)
• UWB: bandwidth larger than 500MHz• Two main camp: DS-UWB (Motolora) vs. MBOA-
OFDM UWB (Intel+TI)
laptops
MobileCluster
cameraspocketPC
CECluster
HDTV
STBs
VCRs
PVRs
audio
systems
tablets
printers
speakers
MP3
PDA
PCCluster
camcorders
ConsoleGames
CordlessPhones
3GHandsets
storagedevices
Scanners
Projector
Ultra WideBand (UWB)
WLAN (WiFi-802.11x)
802.11n100 Mbps (above MAC)
802.11a
802.11g 802.11b
54 Mbps5 GHz
11 Mbps
2.4 GHz
54 Mbps
2.4 GHz
802.11e
Quality of Service
1999 2001 2003 2005 2007
802.11i
Enhanced Security
802.11k
Radio Resource Measurement
Physical Layer Enhancements
IEEE 802.16dIEEE 802.16dAir I/F Fixed BWAAir I/F Fixed BWA
Approved 07/04Approval 05/05 Corrigenda (TGh)
WiMAX 1st certificate 07/05
Chipset for Indoor-outdoor CPE
• Intel is the main driver for WIMAX: Integration in Centrino is the disruptive goal
IEEE 802.16eIEEE 802.16eAir I/F Fixed Air I/F Fixed & Mobile BWA& Mobile BWA
Approval 07/05
Chipset for PCMCIA No handover
Chipset for Centrino Handset
Approval 05/06 Corrigenda (TGh)
Possible delay
200620062005200520042004 2008 2008 20072007
Big Picture –WMAN’s
WiMax (Worldwide Interoperability for Microwave Access)
•Standard & Chipset Availability
Business, SME, SOHO Access Business, SME, SOHO Access
Residential FixedResidential Fixed WDSL BB AccessWDSL BB Access
Nomadic PCNomadic PC
WiFiWiFi
WiFi-Hotspot WiFi-Hotspot FeedingFeeding
Mobile Mobile PC/PADPC/PAD
NB orBTS
2G/3G 2G/3G FeedingFeeding
Hot ZonesHot ZonesCampu
s Airport
WiMAX
Base Station
IEEE 802.16-2004IEEE 802.16-2004
WiMAX Applications in 2005
Fixed Services
Business, SME, SOHO Access Business, SME, SOHO Access
Residential FixedResidential Fixed WDSL BB AccessWDSL BB Access
WiFiWiFi
WiFi-Hotspot WiFi-Hotspot FeedingFeeding
Mobile Mobile PC/PADPC/PAD
Nomadic PCNomadic PC
NB orBTS
2G/3G 2G/3G FeedingFeeding
Hot ZonesHot ZonesCampu
s Airport
WiMAX
Base Station
IEEE 802.16-2004IEEE 802.16-2004& IEEE 802.16e& IEEE 802.16e
WiMAX Applications in 2006-2007
Nomadicity, Solutions for Laptops (PCMCIA)
Business, SME, SOHO Access Business, SME, SOHO Access
Residential FixedResidential Fixed WDSL BB AccessWDSL BB Access
WiFiWiFi
WiFi-Hotspot WiFi-Hotspot FeedingFeeding
NB orBTS
2G/3G 2G/3G FeedingFeeding
Hot ZonesHot ZonesCampu
s Airport
Portable PCPortable PC
Mobile Mobile PC/PADPC/PADWiMAX
Base Station
IEEE 802.16eIEEE 802.16e
WiMAX Applications in 2007-2008
Fully Mobile, Integrated Solutions in Laptops and PAD
IP Network
WCDMA5MHz2Mbps
HSDPA5MHz
10Mbps
CDMA20001xEV-DV1.25MHz5Mbps
MBWA (802.20)OFDM-5MHz (<3.5GHz)
5Mbps (250kmph)
WLAN (802.11)20MHz
54Mbps
UWB (802.15.3a)7.5GHz (3.1-10.6GHz)
480+Mbps
HarmonizedAll IP CN
WMAN (802.16e)OFDM-5MHz (2-6GHz)
15Mbps (60kmph)
Services/Applications
Services/Applications
TD-SCDMA5MHz2Mbps
WWAN (3G and Beyond)
Overlay Networks- the Global Goal
Integration of heterogeneous fixed andmobile networks with varyingtransmission characteristics
verticalhand-over
horizontalhand-over
campus-based
metropolitan area
regional
in-house
Wireless Networks vs. Fixed Networks
• Restrictive regulations of frequencies– Frequencies have to be coordinated, useful frequencies
are almost all occupied
• Low transmission rates– Local 11~54 Mbit/s, regional currently, e.g., ~40 kbit/s
with GPRS/CDMA
• Higher loss-rates due to interference– Emissions of, e.g., engines, lightning
• Higher delays, higher jitter– Connection setup time with several hundred
milliseconds for some wireless systems
Wireless Networks vs. Fixed Networks (Cont.)
• Lower security, simpler active attacking– Radio interface accessible for everyone, base
station can be simulated, thus attracting calls from mobile phones
• Always shared medium– Secure access mechanisms important
• Close and complex inter-layer interaction
Influence of Wireless Communication to the Layered Model
– service location– new applications, multimedia– adaptive applications– congestion and flow control– quality of service– addressing, routing,
device location– hand-over– authentication– media access– multiplexing– media access control– encryption– frequency– modulation– interference– attenuation
• Application layer
• Transport layer
• Network layer
• Data link layer
• Physical layer
OSI or TCP /IP stack MAY NOT be the way to go!
Current Trend : Eliminate layers or introduce hooks such that layers can interact with each other
Classification of Wireless Networks
• Cellular Networks– Organized, base stations that are regularly placed.
Mobiles communicate only with base stations
• Wireless LANs– Less organized; access points with which mobile nodes
communicate
• Ad hoc/Multi-hop networks– No infrastructure; nodes potentially move and network
dynamically changes
• Sensor Networks– application specific; mobility is limited (perhaps to
selected subset of nodes); tiny nodes that are resource and energy constrained
Ad Hoc Network Characteristics
• Peer-to-peer• Multihop• Dynamic• Low power
• Zero-administration• Auto-configured • Autonomous• Really “anytime, anywhere”
Wireless Mesh Networks
Key Players:
MotorolaNortelMicrosoftIntel (802.11s)MeshdynamicsFiretideStrixBellair….
Most the relay nodes are assumed to be static
Possible Applications for Multi-Hop Networks
• Emergency response
• Military communications
• Broadband Internet access sharing
• WLAN coverage extension
• Home and conference networks
• Community networks
The Spectrum Problem
Spectrum Dilemma: We are not running out of spectrum; we simply aren’t using it properly!
All Spectrum May Be Assigned, But … Most Spectrum is Unused
Overview of Open Spectrum
• Primary devices – Utilize assigned spectrum when
desired– Movement and channel utilization
varies over time
• Secondary devices– Seek to utilize remaining “available
channels” without interfering primary users
• Find optimal balance between maximizing spectrum utilization and minimizing harmful interference
Open spectrum enables opportunistic spectrum access to provide 10x Improvement by reusing wasted spectrum
channelsRequirement: cognitive radios
What is a Cognitive Radio?
• Wireless communication radios e.g., 802.11 a/b/g/n, can be described as fixed and adaptive – A fixed radio has its technical characteristics set at the time of
manufacturing– An adaptive radio can respond to channel conditions that
represent one of a finite set of anticipated events
• Cognitive radios– It can dynamically take advantage of spectrum– It provides spectral awareness in support of FCC initiatives in
spectral reuse– Can respond intelligently to an unanticipated event, i.e., a
channel that it has never encountered before – It can take decisions based on many trained observations
Trends – Industry
• Two distinct markets evolve with different technologies and paradigms
Wide area wireless Local access wireless
•Seamless mobility•High speeds•Any-time anywhere•Moderate data rates
•”Cordless” access•Stationary use•High data rates
Trends – Technology
• Increasingly complex and heterogeneous network environment– Many different types of networks, from simple to
complex, operated by different types of operators– Many different access technologies - but several of
those developed today will not survive– More “niche” wireless standards – no single “4G”
radio standard
• Gradually shift towards multi-standard “Ambient Networks”
Wide Area Ambient Networks
Public UMTSNetworks
Public GPRS
Networks
Home
Office
WLAN
WLAN & UWB
WMAN (WiMAX)
WPAN (BT)
End-to-end Reconfigurability for Seamless Experience
Fixed
WLAN
WiMAX
2.5/3G
4G
UWBDVB
DAB
Other Access
Networks
Ubiquitous Access
Pervasive Service
DynamicResource Management
Different administrative domains
All-IP infrastructure
Heterogeneous Systems
Heterogeneous Environments and Contexts
Heterogeneous Devices
Move Forward: Cognitive Networking and System
Automatic Environment
Understanding and Dynamic
Spectrum Utilization
Sense/Aware
Adapt
LearningMistake Correcting
Autonomy