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

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 Current Systems 10 feet100 feet1 mile10 miles 100 kbps 1 Mbps 10 Mbps 100 Mbps 3G Wireless ~ 2GHz BlueTooth 2.4GHz a 5.5GHz Unlicensed b 2.4GHz Unlicensed Peak Data Rate Range 2 mph10 mph30 mph 60 mph $ 500,000 $ 1000 $ 100 $ 500 $ 100 $ 10 $/Cell $/Sub High performance/price High ubiquity and mobility Mobile Speed UWB GHz

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

6 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 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) Barker Key b Physical Layer Parameters: Chip rate:11 MHz Frequency band:Industrial, Scientific and Medical (ISM, unlicensed) GHz Bandwidth:22 MHz - TDD Channel spacing:5 MHz Total of 14 (but only the first 11 are used in the US), with only 3 nonoverlapping channels Number of channels: Transmission modes: (dynamic rate shifting) CCK 1  s 11 chips Barker 727 ns 8 chips CCK WLANs: b

7 Unlicensed national infrastructure (U-NII), 5.5 GHz Total of 12 in three blocks between 5 and 6 GHz Data rate:6, 9, 12, 18, 24, 36, 48, 54 Mbps Modulation:BPSK, QPSK, 16QAM, 64QAM Coding rate:1/2, 2/3, 3/4 Subcarriers:52 Pilot subcarriers:4 G 3.2  s 4  s FFT 52=48+4 tones 64 point FFT Key a Physical Layer Parameters: Symbol duration: 4  s Guard interval:800 ns Subcarrier spacing:312.5 kHz Bandwidth:16.56 MHz - TDD Channel spacing:20 MHz FFT size:64 : BPSKQPSKQAM16QAM R=1/2 48 R=2/ R=3/4 User data rates (Mbps): Frequency band: Number of channels: WLANs: a (g in 2.4 GHz band)

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 a 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 Enterprise Home Public Internet Wireless LAN’s

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 Wireless System Enhancements 10 feet100 feet1 mile10 miles 100 kbps 1 Mbps 10 Mbps 100 Mbps 3G Wireless ~ 2GHz BlueTooth 2.4GHz a 5.5GHz Unlicensed b 2.4GHz Unlicensed Peak Data Rate Range 2 mph10 mph30 mph 60 mph $ 500,000 $ 1000 $ 100 $ 500 $ 100 $ 10 $/Cell $/Sub High performance/price High ubiquity and mobility Mobile Speed Enhanced UWB GHz

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 Smart Antennas 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) SIGNAL INTERFERENCE BEAMFORMER WEIGHTS SIGNAL OUTPUT

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

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 a (4X 54 Mbps) –1.5 Mbps EDGE –19 Mbps WCDMA

17 Rx MIMO Channel Testing W1W1 W2W2 W3W3 W4W4 LO Synchronous test sequences Rx Perform timing recovery and symbol synchronization Record 4x4 complex channel matrix Evaluate capacity and channel correlation LO Mobile Transmitters Test Bed Receivers with Rooftop Antennas Terminal Antennas on a Laptop Tx Rooftop Base Station Antennas 11.3 ft Prototype Dual Antenna Handset 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 Laptop Prototype Antennas mounted on 60 foot tower on 5 story office building Dual-polarized slant 45  1900 MHz sector antennas and fixed multibeam antenna with  beams 4 patch antennas at 1900 MHz separated by 3 inches ( /2 wavelengths) Laptop prototype made of brass with adjustable PCB lid

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

21 Smart Antennas for 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 AP Smart Antenna Interference Smart Antennas can significantly improve the performance of WLANs AP Smart Antenna

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 a 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

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)

25 Asia Telecommunications Study Growing activities to support development of Asia’s expertise in 3G systems are questionable 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

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, increase data rate, and improve quality, without standards changes –Radio resource management techniques, in combination with smart antennas, and multiband/multimode devices