Mobile and Distributed GIS and LBS

1. Mobile and Distributed GIS and LBS Geog 176B Lecture 9

2. The network is the computer Computer Network Software Localizer

3. Wired Networks • “Last Mile to the house” • 300 baud dial-up early ‘80s • 56 kbps dial-up (since mid 1990s) • ISDN 64-128 kbps (digital) • DSL: 1.5Mb down/64Kb up (6Mb/640K in future) • cable modem: 2 Mbps (load dependent) • LANs (local area network) within building or campus • 300 baud RS232 (1970s) • 10MB Ethernet (1980s) • 100MB Ethernet (mid 1990s) • 1GB Ethernet (late 1990s) • WANs (wide area network) connects LANs • shared, public facilities (Internet) • Dedicated Telco leased lines (fixed bandwidth) • T1 (24 x 64 Kbps channels: 1.54MBps) • T3 (28 T1 circuits: 45MBps; requires fiber) • Dedicated fiber (usually SONET protocol) • OC1 (base rate) 50 mbps OC12 = 600 Mbps • OC3 = 150 Mbps OC48 = 2.4Gbps • ‘virtual circuit’ protocols (max. guaranteed bandwidth)

4. Twisted pair wire: (now up to 1Gbps) distance/speed trade-off 150m. max. for highest speed high speed: closet to desktop (using Level 5 cable) low speed: home to Telco office Maximum leased line over copper is T1 (1.4Mbps) Coaxial cable (up to 200Mbps): longer distances (up to 20 miles) was fading but cable TV and Internet brought revival for “last mile” applications Fiber optic (exceeds 100Gbps & doubling every 9 months--twice Moore’s Law) single mode for distances over 1 or 2 miles Multi mode within buildings More “wires”

5. Wireless • infrared (1 mile) • microwave (35 miles line of site) • satellite geostationary (22,000 miles up)--’group’ links • satellite low orbit --individual links • radio--mobile data networks (police) • Wireless LANs (WiFi 802.11b/g) • Cellular data: 3G services • Satellite telephone link

6. Closer to the Wire Types of Protocols • WAN transmission protocols: • T1/T3 (old faithful for copper/fiber dedicated lines) • SONET(Synchronous Optical Network) • Virtual circuits: Frame Relay, SMDS (Switched Mutimegabit Data Service), ATM (Asynchronous Transfer Mode) All are fading! • LAN Transmission Protocols: • Ethernet 10MB/100MB/1GB (the standard) (IEEE 802.3) • Wireless: replaces wires over short distances • 802.11b (WiFi): 11Mbps on 2.4GHz band (crowded spectrum)-300 feet coverage • 802.11g: faster (54 Mbps) version of 802.11a • Bluetooth: small, cheap (eventually) but doesn’t run tcp/ip • Data Communication Protocols • tcp/ip (transmission control program/internet protocol) the standard • Tcp/ip has replaced • WAN: SNA( old IBM proprietary), X.25 (old open) • LAN: XNS (Xerox), IPX (Novell), Ethertalk(Apple), NetBIOS • Internet: interconnected LANs and WANs running tcp/ip • Internet2/NGI: Next Generation Internet univ/vendor coop. research Closer to the User

7. Bluetooth GPS

8. Example: AT&T at UCSB

9. Characteristics of Circuits and Networks • circuit switched v. packet switched • end-to-end connection established (e.g voice call) • or, electronic packet traverses the network (like parcel via UPS) • typology: star, hierarchy, bus, ring • baseband v. broadband • one service/channel/protocol per cable v. Multiple (e.g. cable TV is broadband) • switched v. dedicated lines • compete for circuit when needed • or, have your own all the time • public v. private • share with all others (e.g. Internet) • or, have your own (e.g. Intranet)

10. Networked GIS • Configured within an organization or lab • Collaboration across organizations • Tools relatively undeveloped “Virtual Organization” original vision of web • Web portals offer GIS “services” • Wireless access can be “on-the-spot” • New industry-LBS

11. Ubiquitous Computing • Computing any time, anywhere • Always on, trackers • Monitoring activity • Sensor networks • Localizers, Actuators • The GRID • Sensitive to multiple inputs

12. Emergence of LBS • Convergent technologies • Cell phone • GPS • GIS • Wireless networking • Impact has been on the “where” of computing

13. For highly mobile GISGPS is critical

14. Wearable computing http://www.itmedia.co.jp/broadband/0309/18

15. Vehicle navigation and tracking

16. Time-space Geography Source: Jonathan Raper, City University, London

17. A new role for GIS: highly integrated spatial problem solving • Need a theory of human mobility and access • Need real time multi-source data fusion • GIS continues to play the major role • Tools for 4D GIS only now getting started • Major constraint remains the human computer interface

18. What is GPS? • GPS is a Satellite-based Navigation System • Generic term: Location Determination Technology • Funded by and controlled by the U. S. Department of Defense (DOD). Originally NAVSTAR • Designed for military tasks: Dual Use • Civil uses now far exceed military

19. One of three such systems • GLONASS • Galileo • GPS Blocks I and II • Block III and beyond • Many new LDTs, some using GPS • Pseudolites

20. The GPS System has the following components • Space Segment • Ground/Control Segment • User segment

21. What the Satellite Does Radio signal transmission Onboard atomic clock Metadata in ephemeris Carrier signal

22. The constellation 24 satellites 6 orbital tracks 4 satellites/track 12 hour orbits

23. Control Segment • The Control Segment consists of a system of tracking stations located around the world. • GPS Master Control and Monitor Network located at Schriever Air Force Base in Colorado • These monitor stations measure signals from theSVs which are incorporated into orbital models for each satellite • The models compute precise orbital data (ephemeris) and SV clock corrections for each satellite • The Master Control station uploads ephemeris and clock data to the SVs as they pass over • The SVs then send subsets of the orbital ephemeris data to GPS receivers over radio signals

24. The User Segment: The Signal • Signals Specified In The Federal Radionavigation Plan • PPS: Precise Positioning Service • Military/encrypted • 22 m hor. 27.7 m vert. 200 ns accuracy • SPS: Standard Positioning Service • Civil users • Subject to SA, but turned off May 1st, 2000 • 100m hor. 156m vert. 340 ns accuracy

25. GPS Satellite Signals • The SVs transmit two microwave carrier signals. • The L1 frequency (1575.42 MHz) carries the navigation message and the SPS code signals. • The L2 frequency (1227.60 MHz) is used to measure the ionospheric delay by PPS equipped receivers. • Can process carrier phase delay for extra accuracy

26. Digital signal processing • Three binary clock-tied codes shift the L1 and/or L2 carrier phase. • The C/A code • The P-code • The Y-code • Plus the navigation message

27. Received Signal distance (m) = time (s) * c (m s-1) 4+ distance, three unknowns In GPS

28. Dilution of Precision Ionospheric Effect GDOP-PDOP

29. Pts w/ No Diff Correction

30. Pts w/ Diff Correction

31. Adeline Dougherty’s 176A project

32. Lots of multipath error!

33. Multi-path Error

34. WAAS network • ~25 precisely measured WRS (Wide Area Reference Stations) • Receive signal from GPS satellites, check for error, then broadcast the correction

35. Accuracy Usually about, 4-8m With correction (WAAS), 1-3m $150-300 gets you a new GPS Garmin eTrex Vista $60-150 Garmin Quest $599 WAAS Magellan Meridian Gold GPS$250 WAAS Garmin Forerunner 201 $100-150 Casio Protrek GPS Watch

36. Precision Agriculture GPS enabled innovation

39. Smart dust

40. MEMS and WINS • Microelectromechanical systems • Using semiconductor manufacturing techniques to make analog devices • Also called localizers • Wireless Integrated Network Sensors (WINS) provide distributed network and Internet access to sensors, controls, and processors that are deeply embedded in equipment, facilities, and the environment.

41. Smart Dust Applications: Sensor webs • Personal location • Object location (geosensors) • Autonomous bots (geoprobes) • Inventory control • Localized intelligence for IVHS • Machine control • Infrastructure inspection • Smart homes • Biosensors • Agrisensors!