Transcript Smart Antennas for Wireless Systems

EMERGING TECHNOLOGIES IN
WIRELESS
Jack H. Winters
Chief Scientist, Motia
[email protected]
12/05/03
Slide 1
Thursday, June 30, 2005
Outline
• Technologies
• Service Limitations
• Multiplatform Systems
• Conclusions
Slide 2
Thursday, June 30, 2005
SUMMARY
New wireless technologies:
• Physical Layer:
• WiFi (IEEE802.11a/b/g, n)
• WiMax
• UWB
• Bluetooth
• EvDO
• RFID
•Zigbee
• Applications: VoIP
• Interconnection: Mesh networks, WLAN-WWAN convergence
Slide 3
Thursday, June 30, 2005
Wireless System Enhancements
Peak Data Rate
UWB
100 Mbps
3.1-10.6 GHz
High performance/price
WiMAX
802.11a/g
2.4, 5.5GHz Unlicensed
10 Mbps
802.11b
2.4GHz Unlicensed
1 Mbps
$/Cell
$/Sub
$ 500,000
$ 500
$ 1000
$ 100
$ 100
$ 10
Enhanced
BlueTooth
100 kbps
2.4GHz
High ubiquity and mobility
2G/3G Wireless
0.9, 2GHz
10 feet
2 mph
100 feet
1 mile
10 mph
30 mph
Slide 4
10 miles
60 mph
Range
Mobile Speed
Thursday, June 30, 2005
Service Limitations of Wireless
•
Quality of service for each user is not
consistent:
– Too far away from the access point/base
station/etc.
– Behind a wall
– In a “dead” spot
– Working off a battery, as with a laptop
– Suffering from low bandwidth due to
range/interference
– VoIP applications cannot tolerate fading or
brief outages
Slide 5
Thursday, June 30, 2005
Solutions
•
•
Change among platforms to maximize performance
Further enhance performance of each system
through:
– Smart Antennas
• Being implemented today (e.g., MIMO)
– Ad Hoc Networks
• Interconnections of multiple clients
– Combination of Smart Antennas with Ad Hoc Networks (can
give greater gains than the sum of the two)
Slide 6
Thursday, June 30, 2005
Multiplatform Devices
•
Multimode devices adapt to maximize performance,
minimize cost and/or power:
– Laptops with WiFi, WiMax, and Cellular (GSM, EDGE,
WCDMA, EvDO)
– Handsets with WiFi and Cellular:
•
•
VoIP
Single spatial stream 802.11n under discussion
Slide 7
Thursday, June 30, 2005
Smart Antennas
A smart antenna is a multi-element antenna where the signals
received at each antenna element are intelligently combined to
improve the performance of the wireless system. The reverse is
performed on transmit.
Smart antennas can:
•
•
•
•
Increase signal range
Suppress interfering signals
Combat signal fading
Increase the capacity of wireless systems
Slide 8
Thursday, June 30, 2005
Smart Antennas
SIGNAL
BEAMFORMER
SIGNAL
BEAM
SELECT
SIGNAL
OUTPUT
SIGNAL
OUTPUT
INTERFERENCE
BEAMFORMER
WEIGHTS
INTERFERENCE
Switched Multibeam
Adaptive Antenna Array
Simple beam tracking
Antenna gain of M
limited interference suppression
Suppression of M-1 interferers
limited diversity gain
M-fold multipath diversity gain (with multipath)
With M Tx antennas (MIMO), M-fold data rate
increase in same channel with same total
transmit power (with multipath)
Slide 9
Thursday, June 30, 2005
Multiple-Input Multiple-Output (MIMO) Radio
•
•
With M transmit and M receive antennas, can provide M independent channels, to increase data rate Mfold with no increase in total transmit power (with sufficient multipath) – only an increase in DSP
–
Indoors – up to 150-fold increase in theory
–
Outdoors – 8-12-fold increase typical
Measurements (e.g., AT&T) show 4x data rate & capacity increase in all mobile & indoor/outdoor
environments (4 TX and 4 RX antennas)
–
216 Mbps 802.11a (4X 54 Mbps)
–
1.5 Mbps EDGE
–
19 Mbps WCDMA
Slide 10
Thursday, June 30, 2005
Gains for with Smart Antennas
• WiFi/WiMax (4 antennas)
– 13 dB (one side), 18 dB (both sides) – > 2-4 times range,
throughput
• Cellular (4 antennas):
– >6 dB gain on receive – 2X range, throughput
Slide 11
Thursday, June 30, 2005
Multiplatform Smart Antenna
Systems
• WiFi, WiMax, Cellular:
– Use one array (4 antennas) for all platforms
– Digital interface from array (RFIC) to BB/MAC’s
•
Cable from laptop display back or handset case
– Standard in development:
•
JC-61 (initially for 802.11n) – single merged proposal at next
meeting in July
Slide 12
Thursday, June 30, 2005
JEDEC Standard JC-61
Block Diagram
Baseband
I/Q
802.11n,
WiMax,
Cellular
RFIC
RX_CLK
JESD96
Interface:
A/D, D/A,
Control
Logic
RX_DATA
802.11n , WiMax,
Cellular
TX_DATA
Baseband/MAC
TX_CLK
Processor
Host Interface
Control
Signals
Slide 13
Thursday, June 30, 2005
Mobile Ad Hoc/Mesh Networks
•
•
•
•
Network of wireless hosts which may be mobile
No pre-existing infrastructure
Multiple hops for routing
Neighbors and routing changes with time (mobility, environment)
Slide 14
Thursday, June 30, 2005
Impact of Smart Antennas in Ad
Hoc Networks
•
•
Since smart antennas are a physical layer technique, existing
approaches for MAC/routing in ad hoc networks will work with smart
antennas, but these MAC/routing techniques need to be modified to
achieve the full benefit
Need to use hooks:
– Hooks for frequency assignment techniques to include reusing a
frequency (up to M-1 times).
– Hooks for the inclusion of multiple radio capability to include multiple
radios in the same channel.
– This can be done in such a way to actually reduce the complexity of the
MAC/routing algorithms.
Slide 15
Thursday, June 30, 2005
Conclusions
•
Wide variety of wireless technologies, each with different
capabilities
– Multiplatform devices will allow for adaptation among platforms
to maximize performance
– Smart antennas and ad hoc network techniques with these
various platforms will further enhance and overcome most of
current wireless limitations
•
Adaptation of platforms, signal processing, and
interconnection techniques may look confusing, but if done
correctly will lead to high performance, ubiquitous wireless
systems, without requiring user sophistication
Slide 16
Thursday, June 30, 2005