Indoor Communications Rex Chen rexics uci edu Ubiquitous
Indoor Communications Rex Chen rex@ics. uci. edu Ubiquitous Computing - Winter 2007
Outline n n n Overview Technologies Challenges Paper Discussion Research Progress Conclusion
Overview of Indoor Communication n Lots of electronic gadgets Need for connectivity Usually in proximity q n e. g. 1 to 30 meters Characteristics q q q Residential Homes Corporate Offices Public Facilities
Wired vs. Wireless Indoor Communications?
Indoor Wireless Communication Technologies n n n IEEE 802. 11 a/b/g Bluetooth Ir. DA Zig. Bee Powerline
Electronic Gadgets
A Closer look at 802. 11 WLAN n Actual vs. theoretical bandwidth a major gap q n CSMA/CA overhead (contention-based access) Spectrum Regulations q q 2. 4 to 2. 5 GHz unlicensed spectrum for open usage Interferences with microwave and cordless telephony
802. 11 Logistics n Standardization q IEEE 802. 11 Specification n q Involve multiple parties n n Many revisions Companies, governments Wi-Fi Alliance q 260+ member companies
802. 11 Technicalities n Signal Strength q q n Depend on signal-to-noise ratio Receive power ~ to 1/d 2 (distance square) Handoff Decision q RSSI indicator
Bluetooth n Characteristics q q n Short-range, 2. 4 GHz RF Peak rates up to 1 Mbit/sec Line-of-sight not required Low power, cost, size Applications q Personal Computers n q Keyboard, mouse, printer Communication Devices n Cell phone and wireless headset
Bluetooth Topology n Piconet Formation n n Comprise of master, slave (active), parked (ready), and stand-by nodes Synchronization of hopping pattern required
Bluetooth Transmission q Scatternet – joining of multiple piconets q Frequency Selection
Ir. DA n Characteristics q q Short-range communications with infrared light Requires line-of-sight Low power, cost, size Getting replaced by Bluetooth
Zig. Bee n Characteristics q q q Low data rate, very low power consumption Cheaper than Bluetooth ($1 transceiver) Device Types: n n n q Zig. Bee coordinator(ZC) Zig. Bee Router (ZR) Zig. Bee End Device (ZED) Organized nodes in ad-hoc networks
Zig. Bee in Home Automation
Power line communications n Characteristics q q q n Use electrical power wiring as transmission medium Power plugs are ubiquitous Several competing standards Not widely adopted Interference with outside signals Applications q Home lighting and appliances
The Challenge for Indoor Wireless Communications n Lack of standard or regulation q q n No protection against signal interferences Interoperability issue in power line communications Network planning problems in 802. 11 WLAN q q q Dynamic building configurations Physical object obstruction (e. g. walls, windows) Dead spots
The Challenge for Indoor Wireless Communications (2) n Security Problems q q q Encryption turn off in many access points WEP failure, can be cracked within a few days Detecting unintended signals Unauthorized network access n n n e. g. Using neighbor wireless access point while surfing for child porn Intensive data traffic download of “pirated” data using P 2 P applications (e. g. music, software) Usability q Setting up the wireless links can be difficult
Seidel – On Path Loss Prediction Models for Indoor Communication n Goal n n Understand implications of indoor wireless communication with respect to physical surroundings Measurement Sample q n Grocery store, retail store, two office buildings Model n n Mean path loss increases exponentially with distance Path Loss (d) ~ (d/d 0)n (solve for n)
Seidel – Mean path loss exponent and standard deviation
Seidel - Analysis
Indoor Communication Tools – specifically for IEEE 802. 11 n Access Point Detection q n Wireless Packet Data Capture q n Net. Stumbler, Kismet Omni. Peek (aka, Ethereal) Network Topology Management q Ekahau
Indoor Comm Tools - Net. Stumbler n Demo
Indoor Comm Tools – Ekahau
Indoor Comm Tools – Ekahau (2)
Indoor Comm Tools – Ekahau (3)
Relevant Projects with Indoor Communications n Ambient Networks q Integration of device communications n n e. g. PDA-> (Ir. DA) -> Laptop-> (Bluetooth) -> Mobile -> (GPS) -> Mobile phone network Place. Lab q Indoor location positioning n 802. 11 access point using beacon frames
The Future of Indoor Communications n Everything Wi-Fi enabled?
The Future of Indoor Communications (2) n Extending coverage reach q q n Wi-Fi interface with Wi. MAX Mesh routing Higher throughput q q 802. 11 n, 10 x more bandwidth than 802. 11 a/g Market Demand? n n Multi-networked gaming Wireless IPTV streaming
Concluding Remarks n Many interested parties on indoor communications q Telephony and Cellular carriers n q Wireless Internet Service Providers (WISP) n q Dual-mode Wi-Fi and 3 G handset Inter-network from outdoor to indoor communication Cable Operators n Set-top boxes streaming video contents to multiple indoor clients
The FONERA Movement n http: //www. fon. com
n Open Discussion
- Slides: 32