Wireless Sensor System Design

1. Wireless Sensor System Design A Joint Course of the University of South Florida and Tennessee Technological University Spring 2002 Lecture 7 - Wireless Communication Systems Tennessee Tech UNIVERSITY

2. Weekly Lecture Topics • Course Introduction • Analog and Digital Modulation Methods (1/11) • Fundamentals of Antennas and Propagation (1/18) • Signal Processing Techniques (1/25) • Microwave Systems: Communications Hardware, Noise, Linearity (2/1) • System Test, Evaluation and Documentation / Effective Presentation Styles (2/8) • Preliminary Design Review (student presentations*) (2/15) • Microwave Sensor Technology (2/22) @ TTU • Modern Wireless Communication Systems (3/1) • TBD (3/8) • Critical Design Review (student presentations*) (3/22) • Microelectromechanical Systems (MEMS) Sensors (4/5) • Wireless Sensor System Research (Paul Flikkema from NAU) from USF (4/12) • Review / Course Wrap-up(4/19) * On-site internal reviews/preparation will precede inter-university presentations.

3. Outline • Why wireless communication systems? • Four examples of wireless telecommunications systems • Design criteria as related to class project

4. Wireless Communication Systems: WHY? • Transmission media • Wired - wire/fiber • Wireless - air • Quick installation of infrastructure • e.g., straight to mobile in developing countries • User mobility • Shared access • TDMA • FDMA or combinations of • CDMA

5. Example 1: Satellite Broadcasting Shaped pattern HUB 22,400 miles

6. Example 1: Market for DirecTV • Terrestrial Broadcast TV • An analog system of limited range • Each channel occupies 6 MHz • VHF (CH 2-13): 54-216 MHz • UHF (CH 14-83): 470-890 MHz • Regular Cable: same technology, just over wire • Need for an alternative? • Cable not available everywhere • Cable had a “monopoly” • Analog system had a limited number of channel (82)

7. Example 1: Technology • High-power direct broadcast satellite operating at Ku-band (14/12 GHz) • All signals uplinked from single location • Service (downlink) to any CONUS location • Analog audio and video signals are • Digitized • Compressed (MPEG-2, 8:1) • Encoded • Multiplexed • “Inexpensive” receivers

8. Example 1: Receiver Technology • Ku-band enables small receiving dish • directivity ~1/ • Digital signal provides • CD quality sound • “Better” picture • Additional services • More channels: “500!”

9. Example 1: Summary • Promise of high-quality, nation-wide service obtained • Advantages • Easy to add new customers (database change) • Disadvantages • Large customer and venture investment up-front • No standard among providers • Compression can break down • Cable is catching up (Tom Switched!) • Limited bandwidth, HDTV? • Rainfade (FL - high gain slope and rain rates)

10. Example 1: Gain Slope & Pointing HUB HUB NOT OK OK

11. Example 2: Cell phones • Spatial Isolation w/ channel groups • Time (TDMA) • Freq (FDMA) • Code (CDMA) • Cell size • Capacity • Power • size  0 : wired • Reuse: e.g., N=7 makes a cluster • N  - better isolation • N  - better reuse • more clusters  more reuse  more capacity 3 4 5 3 2 1 6 2 4 7 3 1

12. Example 2: Changing Cells • Handoff • Uses different set of channels • channel groups can be reused when cells are “far” apart • reusing channel increases system capacity 3 4 5 3 2 1 6 2 4 7 3 1

13. Nice Geometry is not Reality! Source: University of Kansas' Information & Telecommunications Technology Center and Kansas Applied Remote Sensing Program

14. Example 3: WLAN: Bluetooth • Cellular idea implemented in extremely small scale • 10 cm - 100 m (10 m nominal) • 2.4 GHz band • Up to 79 channels (@ 220 kHz) separated at 1 MHz intervals • Low power (RF and DC) • FHSS Thanks Asa

15. Example 3: Bluetooth Applications • Internet Bridge • Laptop • Cell Phone • LAN • Peripheral Interface • PC • PDA • Printer • Keyboard • Mouse Aware devices!

16. Example 4: Wireless Sensor Systems • Wireless Sensing: • Non-invasive, remote sensing • Wireless Link: • Ease of installation - Low impact • Wide coverage region • Unique characteristic: Low bandwidth requirements • In this class we’ve discussed both wireless sensingandcommunications

17. Example 4: Wireless Sensing Active Radar and Lidar Speed and position PROXIMITY Passive Radiometry and IR Imaging Composition Thermal profile: measure emissivity for different wavelengths

18. Example 4: Wireless Link

19. Example 4 - Bottom Line • Wireless sensors • In situ measurement • Non-invasive • Ease of placement • Mobility • Ubiquitous

20. So what is next: Hype or Buzz? • Three years ago: • Satellite based global cellular systems • Two years ago: • Satellite based broadband systems • Last few years: • 3G

21. So what is next – the Reality • Satellite based global cellular systems • Iridium and Globalstar (bankrupt), ICO (DNS) • Satellite based broadband systems • Teledesic (designed and redesigned: 800 to 30 satellites), Spaceway, etc. still not launched • 3G: Promise of mobile internet and telematics • Is there the bandwidth? Is there a standard?

22. So what is next – the Reality • Satellite based global cellular systems • Iridium and Globalstar (bankrupt), ICO (DNS) • Satellite based broadband systems • Teledesic (designed and redesigned: 800 to 30 satellites), Spaceway, etc. still not launched • 3G: Promise of mobile internet and telematics • Is there the bandwidth? Is there a standard? Is there a demand?

23. So what is happening? • WLAN • 802.11b (11 Mbps) and Bluetooth (720 kbps) • Satellite based systems • XM and Sirius digital radio • OnStar telematics • In building wireless • Your mobile phone becomes part of the company exchange inbuilding • Maintains regular mobile functions off-campus • SEEMS THE FIELD IS MARKET DRIVEN!

24. Comm Systems: Pertinent Design Criteria • The bottom line: What signal quality do you need? Quantified by Signal-to-Noise Ratio (SNR) • Optimize signal power (S) and bandwidth (B) given noise constraints • Drives the design of: • Antennas • Amplifiers • Range • Data Rates • Filters • Processing • Everything

25. Wireless Communications Summary • Wireless advantages: • Mobility and potentially reduced infrastructure costs • Wireless disadvantages: • Limited bandwidth and more expensive user devices • Control Power and Bandwidth to achieve desired • SNR ratio (signal quality) • Range • Data rates

26. Design Criteria as Related to Project • Range • frequency of operation, amplifier gains, antennas, etc. • Beamwidth • Directivity vs. beamwidth • Bandwidth • Baseband limited by soundcard < 20 kHz • RF limited by FCC ISM band constraints • Filters, sampling rates, etc. • Signal levels (RF, baseband and DC)

27. Signal Levels • Sensor to Baseband TX • Baseband TX to IF TX • IF TX to RF TX • Wireless Link: RF TX to RF RX • RF TX to IF TX • IF TX to Baseband RX

28. Signal Levels • Sensor to Baseband TX • Baseband TX to IF TX • IF TX to RF TX • Wireless Link: RF TX to RF RX • RF TX to IF TX • IF TX to Baseband RX • Bottom Line: Sensor to PC • Can link be transparent to system?

29. Signal Levels • Sensor to Baseband TX • Baseband TX to IF TX • IF TX to RF TX • Wireless Link: RF TX to RF RX • RF TX to IF TX • IF TX to Baseband RX • Bottom Line: Sensor to PC • Can link be transparent to system? • DC requirements

30. References • Gagliardi, Introduction to Communications Engineering, 2nd Edition. • Rappaport, Wireless Communication Systems • Ulaby, et. al., Microwave Remote Sensing • Telecommunication systems • www.directv.com • www.bluetooth.com, www.bluetooth.org • Sensor systems • www.atstrack.com

31. Two Month Course Schedule March • Week 8 (25-1) • Second progress report • Week 9 (4-8) • Review peer reports • Spring Break (11-15) • Week 10 (18-22) • Critical Design Review • Week 11 (25-29) • No TTU class (F) February • Week 4 (28-1) • First progress report • Week 5 (4-8) • Review peer reports • Week 6 (11-15) • Preliminary Design Review • Week 7 (18-22) • Weller at TTU 1. All inputs are due on Friday of the specified week - no exceptions 2. Reviews of peer reports must be completed before the lecture on Friday

32. Anything else?