1. Indoor Communications Rex Chen rex@ics.uci.edu Ubiquitous Computing - Winter 2007

2. Outline Overview Technologies Challenges Paper Discussion Research Progress Conclusion

3. Overview of Indoor Communication Lots of electronic gadgets Need for connectivity Usually in proximity  e.g. 1 to 30 meters Characteristics  Residential Homes  Corporate Offices  Public Facilities

4. Wired vs. Wireless Indoor Communications?

5. Indoor Wireless Communication Technologies IEEE 802.11a/b/g Bluetooth IrDA ZigBee Powerline

6. Electronic Gadgets

7. A Closer look at 802.11 WLAN Actual vs. theoretical bandwidth a major gap  CSMA/CA overhead (contention-based access) Spectrum Regulations  2.4 to 2.5 GHz unlicensed spectrum for open usage  Interferences with microwave and cordless telephony

8. 802.11 Logistics Standardization  IEEE 802.11 Specification Many revisions  Involve multiple parties Companies, governments Wi-Fi Alliance  260+ member companies

9. 802.11 Technicalities Signal Strength  Depend on signal-to-noise ratio  Receive power ~ to 1/d 2 (distance square) Handoff Decision  RSSI indicator

10. Bluetooth Characteristics  Short-range, 2.4 GHz RF  Peak rates up to 1 Mbit/sec  Line-of-sight not required  Low power, cost, size Applications  Personal Computers Keyboard, mouse, printer  Communication Devices Cell phone and wireless headset

11. Bluetooth Topology Piconet Formation Comprise of master, slave (active), parked (ready), and stand-by nodes Synchronization of hopping pattern required

12. Bluetooth Transmission  Scatternet – joining of multiple piconets  Frequency Selection

13. IrDA Characteristics  Short-range communications with infrared light  Requires line-of-sight  Low power, cost, size  Getting replaced by Bluetooth

14. ZigBee Characteristics  Low data rate, very low power consumption  Cheaper than Bluetooth ($1 transceiver)  Device Types: ZigBee coordinator(ZC) ZigBee Router (ZR) ZigBee End Device (ZED)  Organized nodes in ad-hoc networks

15. ZigBee in Home Automation

16. Power line communications Characteristics  Use electrical power wiring as transmission medium  Power plugs are ubiquitous  Several competing standards  Not widely adopted  Interference with outside signals Applications  Home lighting and appliances

17. The Challenge for Indoor Wireless Communications Lack of standard or regulation  No protection against signal interferences  Interoperability issue in power line communications Network planning problems in 802.11 WLAN  Dynamic building configurations  Physical object obstruction (e.g. walls, windows)  Dead spots

18. The Challenge for Indoor Wireless Communications (2) Security Problems  Encryption turn off in many access points WEP failure, can be cracked within a few days  Detecting unintended signals  Unauthorized network access e.g. Using neighbor wireless access point while surfing for child porn Intensive data traffic download of “pirated” data using P2P applications (e.g. music, software) Usability  Setting up the wireless links can be difficult

19. Seidel – On Path Loss Prediction Models for Indoor Communication Goal Understand implications of indoor wireless communication with respect to physical surroundings Measurement Sample  Grocery store, retail store, two office buildings Model Mean path loss increases exponentially with distance Path Loss (d) ~ (d/d 0 ) n (solve for n)

20. Seidel – Mean path loss exponent and standard deviation

21. Seidel - Analysis

22. Indoor Communication Tools – specifically for IEEE 802.11 Access Point Detection  NetStumbler, Kismet Wireless Packet Data Capture  OmniPeek (aka, Ethereal) Network Topology Management  Ekahau

23. Indoor Comm Tools - NetStumbler Demo

24. Indoor Comm Tools – Ekahau

25. Indoor Comm Tools – Ekahau (2)

26. Indoor Comm Tools – Ekahau (3)

27. Relevant Projects with Indoor Communications Ambient Networks  Integration of device communications e.g. PDA-> (IrDA) -> Laptop-> (Bluetooth) -> Mobile -> (GPS) -> Mobile phone network PlaceLab  Indoor location positioning 802.11 access point using beacon frames

28. The Future of Indoor Communications Everything Wi-Fi enabled?

29. The Future of Indoor Communications (2) Extending coverage reach  Wi-Fi interface with WiMAX  Mesh routing Higher throughput  802.11n, 10x more bandwidth than 802.11a/g  Market Demand? Multi-networked gaming Wireless IPTV streaming

30. Concluding Remarks Many interested parties on indoor communications  Telephony and Cellular carriers Dual-mode Wi-Fi and 3G handset  Wireless Internet Service Providers (WISP) Inter-network from outdoor to indoor communication  Cable Operators Set-top boxes streaming video contents to multiple indoor clients

31. The FONERA Movement http://www.fon.com

32. Open Discussion