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Next Generation Wireless Systems and Smart Antennas

Next Generation Wireless Systems and Smart Antennas. Jack H. Winters. April 25, 2003 jack@jackwinters.com. Goal. Wireless communications, anywhere, in any form In any form: high-speed data (Internet) voice audio (music) video Anywhere: home buildings (office) pedestrian vehicles.

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Next Generation Wireless Systems and Smart Antennas

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  1. Next Generation Wireless Systems and Smart Antennas Jack H. Winters April 25, 2003 jack@jackwinters.com

  2. Goal • Wireless communications, anywhere, in any form • In any form: • high-speed data (Internet) • voice • audio (music) • video • Anywhere: • home • buildings (office) • pedestrian • vehicles

  3. OUTLINE • Current Systems • Current Trends • Technical Issues • Smart Antennas • Radio Resource Management • ITRI Study on China • Conclusions

  4. $/Cell $/Sub UWB 3.1-10.6 GHz $ 500,000 $ 1000 $ 100 $ 500 $ 100 $ 10 802.11a 5.5GHz Unlicensed 802.11b 2.4GHz Unlicensed 3G Wireless ~ 2GHz Current Systems Peak Data Rate High performance/price 100 Mbps 10 Mbps 1 Mbps BlueTooth 2.4GHz 100 kbps High ubiquity and mobility Range 10 feet 100 feet 1 mile 10 miles Mobile Speed 60 mph 2 mph 10 mph 30 mph

  5. Cellular Data • CDPD (US) < 10 kbps • GPRS = 30-40 kbps • EDGE/1xRTT = 80 kbps • WCDMA = 100 kbps (starting in Japan, but not for several years in US)

  6. WLANs: 802.11b Barker Barker CCK CCK 1 ms 11 chips 727 ns 8 chips Key 802.11b Physical Layer Parameters: Data rate: • 1, 2, 5.5, 11 Mbps Modulation/Spreading: • Direct Sequence Spread Spectrum (DSSS) • DBPSK, DQPSK with 11-chip Barker code (1, 2 Mbps) (this mode stems from the original 802.11 standard) • 8-chip complementary code keying (CCK) (5.5, 11 Mbps) • optional: packet binary convolutional coding (PBCC), 64 state, rate 1/2 CC (BPSK 5.5 Mbps, QPSK 11 Mbps) Transmission modes:(dynamic rate shifting) Chip rate: 11 MHz Frequency band: Industrial, Scientific and Medical (ISM, unlicensed) 2.4 - 2.4835 GHz Bandwidth: 22 MHz - TDD Channel spacing: 5 MHz Number of channels: Total of 14 (but only the first 11 are used in the US), with only 3 nonoverlapping channels

  7. WLANs: 802.11a (g in 2.4 GHz band) 3.2 ms FFT G 4 ms 52=48+4 tones 64 point FFT Key 802.11a Physical Layer Parameters: Data rate: 6, 9, 12, 18, 24, 36, 48, 54 Mbps Modulation: BPSK, QPSK, 16QAM, 64QAM Coding rate: 1/2, 2/3, 3/4 User data rates (Mbps): Subcarriers: 52 BPSK QPSK QAM16 QAM64 Pilot subcarriers: 4 R=1/2 6 12 24 FFT size: 64 R=2/3 48 4 ms Symbol duration: R=3/4 9 18 36 54 Guard interval: 800 ns Subcarrier spacing: 312.5 kHz Bandwidth: 16.56 MHz - TDD Channel spacing: 20 MHz Frequency band: Unlicensed national infrastructure (U-NII), 5.5 GHz Number of channels: Total of 12 in three blocks between 5 and 6 GHz :

  8. WLAN Evolution • Start with wireless data access (802.11b) (hotspots) • Extend range and migrate to: • Voice • Audio (music) • Video • Mobility • Higher data rates (54 Mbps - 802.11a and higher)

  9. Technical Issues • Voice/Music streaming/Video streaming (802.11e) • Universal coverage (Internet roaming) • Range • Higher data rates • Capacity/Interference • Key constraint: Stay within existing standards/standard evolution (enhance performance within standards and drive standards evolution)

  10. Internet Roaming • Seamless handoffs between WLAN and WAN • high-performance when possible • ubiquity with reduced throughput • Management/brokering of consolidated WLAN and WAN access • Adaptive or performance-aware applications • Nokia GPRS/802.11b PCMCIA card • NTT DoCoMo WLAN/WCDMA trial Cellular Wireless Internet Wireless LAN’s Home Enterprise Public

  11. Technical Issues • Voice/Music streaming/Video streaming (802.11e) • Universal coverage (Internet roaming) • Range • Higher data rates • Capacity/Interference • Key constraint: Stay within existing standards/standard evolution (enhance performance within standards and drive standards evolution)

  12. $/Cell $/Sub UWB 3.1-10.6 GHz $ 500,000 $ 1000 $ 100 $ 500 $ 100 $ 10 802.11a 5.5GHz Unlicensed 802.11b 2.4GHz Unlicensed 3G Wireless ~ 2GHz Wireless System Enhancements Peak Data Rate High performance/price 100 Mbps 10 Mbps Enhanced 1 Mbps BlueTooth 2.4GHz 100 kbps High ubiquity and mobility Range 10 feet 100 feet 1 mile 10 miles 60 mph Mobile Speed 2 mph 10 mph 30 mph

  13. Enhancements • Smart Antennas (keeping within standards): • Range increase • Interference suppression • Capacity increase • Data rate increase using multiple transmit/receive antennas (MIMO) • Radio resource management techniques (using cellular techniques in WLANs): • Dynamic packet assignment • Power control • Adaptive coding/modulation/smart antennas

  14. SIGNAL INTERFERENCE BEAMFORMER WEIGHTS INTERFERENCE Smart Antennas SIGNAL OUTPUT • Smart Antennas significantly improve performance: • Higher antenna gain with multipath mitigation (gain of M with M-fold diversity)  Range extension • Interference suppression (suppress M-1 interferers)  Quality and capacity improvement • With smart antennas at Tx/Rx  MIMO capacity increase(M-fold)

  15. BEAM SELECT SIGNAL SIGNAL OUTPUT BEAMFORMER INTERFERENCE Smart Antennas for Cellular • Key enhancement technique to increase system capacity, extend coverage, and improve user experience in cellular (IS-136) Uplink Adaptive Antenna SIGNAL SIGNAL OUTPUT INTERFERENCE BEAMFORMER WEIGHTS Downlink Switched Beam Antenna In 1999, combining at base stations changed from MRC to MMSE for capacity increase

  16. Multiple-Input Multiple-Output (MIMO) Radio • With M transmit and M receive antennas, can provide M independent channels, to increase data rate M-fold 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 • AT&T measurements 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

  17. 11.3 ft Prototype Dual Antenna Handset Rooftop Base Station Antennas MIMO Channel Testing MobileTransmitters Test Bed Receivers with RooftopAntennas W1 Tx Rx • Perform timing recovery and symbol synchronization • Record 4x4 complex channel matrix • Evaluate capacity and channel correlation W2 Rx Tx Rx Tx W3 Terminal Antennas on a Laptop Rx Tx W4 Synchronous test sequences LO LO Mobile Transmitters

  18. DIVERSITY TYPES • Spatial: Separation – only ¼ wavelength needed at terminal • Polarization: Dual polarization (doubles number of antennas in one location • Pattern: Allows even closer than ¼ wavelength • 4 or more antennas on a PCMCIA card • 16 on a handset • Even more on a laptop

  19. MIMO Antennas Base Station Antennas • Antennas mounted on 60 foot tower on 5 story office building • Dual-polarized slant 45 1900 MHz sector antennas and fixed multibeam antenna with 4 - 30 beams Laptop Prototype • 4 patch antennas at 1900 MHz separated by 3 inches (/2 wavelengths) • Laptop prototype made of brass with adjustable PCB lid

  20. MIMO Field Test Results • Measured capacity distribution is close to the ideal for 4 transmit and 4 receive antennas

  21. Smart Antenna Smart Antenna AP AP Smart Antennas for WLANs Interference Smart Antennas can significantly improve the performance of WLANs • TDD operation (only need smart antenna at access point or terminal for performance improvement in both directions) • Interference suppression  Improve system capacity and throughput • Supports aggressive frequency re-use for higher spectrum efficiency, robustness in the ISM band (microwave ovens, outdoor lights) • Higher antenna gain  Extend range (outdoor coverage) • Multipath diversity gain  Improve reliability • MIMO (multiple antennas at AP and laptop)  Increase data rates

  22. Smart Antennas • Adaptive MIMO • Adapt among: • antenna gain for range extension • interference suppression for capacity (with frequency reuse) • MIMO for data rate increase • With 4 antennas at access point and terminal, in 802.11a have the potential to provide up to 216 Mbps in 20 MHz bandwidth within the standard • In EDGE/GPRS, 4 antennas provide 4-fold data rate increase (to 1.5 Mbps in EDGE) • In WCDMA, BLAST techniques proposed by Lucent, with 19 Mbps demonstrated • In UWB, smart antennas at receiver provide range increase at data rates of 100’s Mbps

  23. Radio Resource Management • Use cellular radio resource management techniques in WLANs: Adaptive coding/modulation, dynamic packet assignment, power control • Use software on controller PC for multiple access points to analyze data and control system • Power control to permit cell ‘breathing’ (for traffic spikes) • Dynamic AP channel assignment • Combination of radio resource management and smart antennas yields greater gains than sum of gains

  24. International Technology Research Institute • Study on Wireless Communication Technology and Systems • ITRI Wireless Comm. Technology (EU, Japan, 2000) • ITRI Asian Telecomm. Update (HK, Taiwan, 2001) • ITRI Asian Telecomm. Update (PRC, March-April, 2003) • http://itri2.org

  25. Asia Telecommunications Study • Comparing the observed R&D trends in Asia with those from the previous wireless study in Europe and Japan we may conclude: • Magnitude of R&D activities in Europe and Japan is much larger • System-based R&D is limited in Asia • Growing activities to support development of Asia’s expertise in 3G systems are questionable

  26. Conclusions • We are evolving toward our goal of universal high-speed wireless access, but technical challenges remain • These challenges can be overcome by the use of: • Smart antennas to reduce interference, extend range, increasedata rate, and improve quality, without standards changes • Radio resource management techniques, in combination with smart antennas, and multiband/multimode devices

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