Transcript Unit 1 (2) - WordPress.com

Spectral Allocation
Cellular
Phones
Cordless
Phones
Wireless
LANs
Others
Europe
USA
Japan
GSM 450-457, 479486/460-467,489496, 890-915/935960,
1710-1785/18051880
UMTS (FDD) 19201980, 2110-2190
UMTS (TDD) 19001920, 2020-2025
CT1+ 885-887, 930932
CT2
864-868
DECT
1880-1900
IEEE 802.11
2400-2483
HIPERLAN 2
5150-5350, 54705725
RF-Control
27, 128, 418, 433,
868
AMPS, TDMA, CDMA
824-849,
869-894
TDMA, CDMA, GSM
1850-1910,
1930-1990
PDC
810-826,
940-956,
1429-1465,
1477-1513
PACS 1850-1910, 19301990
PACS-UB 1910-1930
PHS
1895-1918
JCT
254-380
902-928
IEEE 802.11
2400-2483
5150-5350, 5725-5825
IEEE 802.11
2471-2497
5150-5250
RF-Control
315, 915
RF-Control
426, 868
Evolution of Current Systems
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Wireless systems today
 2G + 2.5G Cellular: ~30-70 Kb/s.
 WLANs: ~10 Mb/s.
Next Generation
 2.75G + 3G Cellular: ~300 Kb/s.
 WLANs: ~70 Mb/s.
Technology Enhancements
 Hardware: Better batteries. Better circuits/processors. Cooptimization with transmission schemes.
 Link: Antennas, modulation, coding, adaptivity, DSP, BW.
 Network: Dynamic resource allocation, Mobility support.
2.5G – Upgrade options
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GSM
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High Speed Circuit Switched Data (HSCSD)
General Packet Radio Service (GPRS)
Enhanced Data rate for GSM Evolution
(EDGE)
IS-95
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IS-95A provides data rates up to 14.4 kbps
IS-95B provides rates up to 64 kbps (2.5G)
3G Vision
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Universal global roaming
Multimedia (voice, data & video)
Increased data rates
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384 kbps while moving
2 Mbps when stationary at specific locations
Increased capacity (more spectrally efficient)
IP architecture
Problems
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No killer application for wireless data as yet
Vendor-driven
Migration To 3G
3G
2.75G
Intermediate
Multimedia
2.5G
Multimedia
Packet Data
2G
Digital Voice
1G
Analog Voice
GPRS
GSM
EDGE
W-CDMA
(UMTS)
384 Kbps
Up to 2 Mbps
115 Kbps
NMT
9.6 Kbps
GSM/
GPRS
TD-SCDMA
(Overlay)
115 Kbps
2 Mbps?
TDMA
TACS
9.6 Kbps
iDEN
9.6 Kbps
iDEN
PDC
(Overlay)
9.6 Kbps
AMPS
CDMA 1xRTT
CDMA
14.4 Kbps
/ 64 Kbps
PHS
1984 - 1996+
1992 - 2000+
cdma2000
1X-EV-DV
PHS
(IP-Based)
144 Kbps
64 Kbps
2001+
2003+
Over 2.4 Mbps
2003 - 2004+
Source: U.S. Bancorp Piper Jaffray
CDMA2000 Pros and Cons
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Evolution from original Qualcomm CDMA
 Now known as cdmaOne or IS-95
Better migration story from 2G to 3G
 cdmaOne operators don’t need additional spectrum
 1xEVD0 promises higher data rates than UMTS, i.e. W-CDMA
Better spectral efficiency than W-CDMA(?)
 Arguable (and argued!)
CDMA2000 core network less mature
 cdmaOne interfaces were vendor-specific
 Hopefully CDMA2000 vendors will comply w/ 3GPP2
W-CDMA (UMTS) Pros and Cons
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Wideband CDMA
 Standard for Universal Mobile Telephone Service (UMTS)
Committed standard for Europe and likely migration path for
other GSM operators
 Leverages GSM’s dominant position
Requires substantial new spectrum
 5 MHz each way (symmetric)
Legally mandated in Europe and elsewhere
Sales of new spectrum completed in Europe
 At prices that now seem exorbitant
TD-SCDMA
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Time division duplex (TDD)
Chinese development
 Will be deployed in China
Good match for asymmetrical traffic!
Single spectral band (1.6 MHz) possible
Costs relatively low
 Handset smaller and may cost less
 Power consumption lower
 TDD has the highest spectrum efficiency
Power amplifiers must be very linear
 Relatively hard to meet specifications
Current Wireless Systems
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Cellular Systems
Wireless LANs (802.11a/b/g, Wi-Fi)
Satellite Systems
Paging Systems
Bluetooth
Ultrawideband radios (UWB)
Zigbee/802.15.4 radios
WiMAX (802.16)
Wireless Local Area
Networks (WLANs)
01011011
0101
1011
Internet
Access
Point
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WLANs connect “local” computers (~100 m range)
Breaks data into packets
Channel access is shared (random access)
Backbone Internet provides best-effort service
 Poor performance in some app’s (e.g. video)
Wireless LAN Standards (Wi-Fi)
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802.11b (Current Generation)
 Standard for 2.4GHz ISM band (bw 80 MHz)
 Frequency hopped spread spectrum
 1.6-10 Mbps, 500 ft range
802.11a (Emerging Generation)
 Standard for 5GHz NII band (bw 300 MHz)
 OFDM with time division
 20-70 Mbps, variable range
 Similar to HiperLAN in Europe
802.11g (New Standard)
 Standard in both 2.4 GHz and 5 GHz bands
 OFDM (multicarrier modulation)
 Speeds up to 54 Mbps
In future
all WLAN
cards will
have all 3
standards...
HIPERLAN
• Types 1-4 for different user types
- Frequency bands: 5.15-5.3 GHz, 17.1- 17.3 GHz
• Type 1
- 5.15-5.3 GHz band
- 23 Mbps, 20 MHz Channels
- 150 foot range (local access only)
- Protocol support similar to 802.11
- Peer to peer architecture
- ALOHA channel access
• Types 2-3
- Wireless ATM
- Local access and wide area services
- Standard under development
- Two components: access and
mobility support
8C32810.63a-Cimini-7/98
Satellite Systems
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Cover very large areas
Different orbit heights
 GEOs (39000 Km) via MEOs to LEOs (2000 Km)
 Trade-off between coverage, rate, and power budget!
Optimized for one-way transmission:
 Radio (e.g. DAB) and movie (SatTV) broadcasting
Most two-way systems struggling or bankrupt...
 (Too) expensive alternative to terrestrial systems
 (But: a few ambitious systems on the horizon)
Satellite networks: GEO
Japan
Gateway
Public
networks
Control
station
GEO
Singapore
Gateway
Control
station
Public
networks
Satellite networks: LEO
Japan
LEO
Gateway
Public
networks
Control
station
Singapore
LEO
Inter-satellite link
Gateway
Control
station
Public
networks
Paging Systems
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Simplex
Limited to worldwide coverage possible
Broadcast / simulcast
Reliable  large Txd. Power, Low data rate
Paging
towers
PSTN
Paging
Control
center
Paging
towers
Other Wireless Systems
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Cordless telephone systems
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Dedicated Base Station
Limited coverage
No handoff support
PSTN
Fixed
Base
Station
A general WLL setup
Bluetooth
A new global standard for data and voice
Cable replacement RF technology
• Short range (10 meters)
• 2.4 GHz band
• 1 Data (700 Kbps) and 3 Voice channels
• Supported by over 200 telecommunications and
computer companies
Goodbye Cables !
Ultimate Headset
Cordless Computer
Automatic Synchronization
In the Office
At Home
Bluetooth Specifications
Connection Type
Spread Spectrum (Frequency
Hopping)
MAC Scheme
FH-CDMA
Spectrum
2.4 GHz ISM
Modulation
Gaussian Frequency Shift Keying
Transmission Power
1 mw – 100 mw
Aggregate Data Rate
1 Mbps
Range
30 ft
Supported Stations
8 devices
Voice Channels
3
Data Security- Authentication Key
128 bit key
Data Security-Encryption Key
8-128 bits (configurable)
UltraWideband Radio (UWB)
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Impulse radio: sends pulses of tens of picoseconds (10-12) to
nanoseconds (10-9) - duty cycle of only a fraction of a percent
Uses a lot of bandwidth (order of GHz)
Low probability of detection by others + beneficial interference
properties: low transmit power (density) spread over wide bandwidth
This also results in short range.
But : Excellent positioning (ranging) capability + potential of high data
rates
Multipath highly resolvable: both good and bad
 Can use e.g. OFDM or equalization to get around multipath
problem.
Why is UWB interesting?
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Unique Location and Positioning properties
 1 cm accuracy possible
Low Power CMOS transmitters
 100 times lower than Bluetooth for same range/data rate
Very high data rates possible (although low spectral efficiency) - 500
Mbps at ~10 feet range under current regulations
7.5 Ghz of “free spectrum” in the U.S.
 FCC (Federal Communications Commission) recently legalized UWB
for commercial use in the US
 Spectrum allocation overlays existing users, but allowed power level
is very low, to minimize interference
“Moore’s Law Radio”
 Data rate scales with the shorter pulse widths made possible with
ever faster CMOS circuits
IEEE 802.15.4/ZigBee radios
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Low-Rate WPAN (Wireless Personal Area Network) - for
communications < 30 meters.
Data rates of 20, 40, 250 kbps
Star topology or peer-to-peer operation, up to 255 devices/nodes
per network
Support for low-latency devices
CSMA-CA (carrier sense multiple access with collision avoidance)
channel access
Very low power consumption: targets sensor networks (batterydriven nodes, lifetime maximization)
Frequency of operation in ISM bands
WiMAX: Worldwide Interoperability
for Microwave Access
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Standards-based (PHY layer: IEEE 802.16 Wireless MAN family/ETSI
HiperMAN) technology, enabling delivery of ”last mile” (outdoor) wireless
broadband access, as an alternative to cable and DSL (MAN = Metropolitan
Area Network). Several bands possible.
OFDM-based adaptive modulation, 256 subchannels. TDM(A)-based.
Antenna diversity/MIMO capability. Advanced coding + HARQ.
Fixed, nomadic, portable, and mobile wireless broadband connectivity
without the need for direct line-of-sight (LOS) to base station.
In a typical cell radius deployment of 3 to 10 kms, expected to deliver
capacities of up to 40 Mbps per channel, for fixed and portable access.
Mobile network deployments are expected to provide up to 15 Mbps of
capacity within a typical cell radius deployment of up to 3 kms.
WiMAX technology already has been incorporated in some notebook
computers and PDAs. Potentially important part of 4G?
Data rate
100 Mbit/sec
UWB
802.11g
10 Mbit/sec
1 Mbit/sec
100 kbits/sec
802.11a
802.11b
3G
Bluetooth
ZigBee
ZigBee
UWB
10 kbits/sec
0 GHz 1GHz 2 GHz 3 GHz 4 GHz 5 GHz 6 GHz
Frequencies occupied
Range
10 km
1 km
100 m
10 m
3G
802.11a
802.11b,g
ZigBee
Bluetooth
ZigBee
UWB
UWB
1m
0 GHz 1GHz 2 GHz 3 GHz 4 GHz 5 GHz 6 GHz
Power Dissipation
10 W
802.11bg
3G
1W
802.11a
100 mW
Bluetooth
UWB
ZigBee
10 mW
ZigBee
UWB
1 mW
0 GHz
1GHz
2 GHz
3 GHz
4 GHz
5 GHz
6 GHz
Emerging Systems
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Ad hoc wireless networks
Sensor networks
Distributed control networks
Ad-Hoc Networks
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Peer-to-peer communications.
No backbone infrastructure (no base stations).
i.e. “Truly wireless”!
Routing can be multihop.
Topology is dynamic in time; networks self-organize.
No centralized cooordination.
Fully connected, even with different link SINRs (signal-tointerference plus noise ratios)
Sensor Networks
Energy is the driving constraint
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Nodes typically powered by nonrechargeable batteries.
Data (sensor measurements) flow to one centralized location (sink
node, data fusion center).
Low per-node rates - but up to 100,000 nodes.
Sensor data highly correlated in time and space.
Nodes can cooperate in transmission, reception, compression, and
signal processing.
Energy-Constrained Nodes
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Each node can only send a finite number of bits.
 Transmit energy minimized by maximizing bit time
 Circuit energy consumption increases with bit time
 Introduces a delay versus energy tradeoff for each bit!
Short-range networks must consider transmit, circuit, and
processing energy - jointly.
 Most sophisticated transmission techniques not necessarily
most energy-efficient!
 Sleep modes save energy - but complicate networking.
Changes everything about the network design:
 Bit allocation must be optimized across all protocols.
 Delay vs. throughput vs. node/network lifetime tradeoffs.
 Optimization of node cooperation.