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Exploring Wireless Communication in Mobile Computing

This paper discusses signal propagation through the air, reasons for signal influence, multi-path challenges, wireless techniques like multiplexing, implications on network capabilities, Mobile IP basics, RFID operating principles, network services, middleware roles, location sensing techniques, and privacy concerns in ubiquitous computing.

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Exploring Wireless Communication in Mobile Computing

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  1. Mobile and Ubiquitous ComputingRevision George Roussos g.roussos@dcs.bbk.ac.uk

  2. Wireless Communication • Signal propagation through the air • Reasons that the signal is influenced • fading (frequency dependent) • shadowing • reflection at large obstacles • refraction depending on the density of a medium • scattering at small obstacles • diffraction at edges • Especially difficult case: multi-path

  3. Wireless comms, part 2 • Especially difficult case: multi-path • Hidden and exposed terminal • Far and near terminal

  4. Wireless Techniques • Sharing the air • Ways of multiplexing communication • space (si) • time (t) • frequency (f) • code (c) • Cellular networks as an example • Communications algorithms (aloha etc)

  5. Example: Wireless Characteristics • Implication: signal interacts with the environment • noise, echoes (multi-path, timing), blocking • objects, walls, other sources, weather • Implication: network topology very dynamic • hosts come and go, loss of connectivity, variable density • Result: degradation/variability of capability to communicate, errors • Networks and applications must deal with this

  6. Mobile IP • Actors and roles • Basics of operation • What does it give us over standard IP

  7. RFID Operating Principle • Tag and reader components • Energy transmission techniques • RFID types • Magnetic (near) field (LF or HF) • Electric (UHF) • Choice influences paramteters of operation • e.g. range, bandwidth, size • Standard types

  8. RFID flavours • Classification (e.g. HF, UHF etc) • Advantages and disadvantages • Appropriate uses

  9. Network Services • Resolution • Information • Authentication • Role of each • Operation and examples

  10. Middleware • Role in the RFID infrastructure • Operating principle • Filtering and aggregation • With examples

  11. Location sensing • Location sensing techniques • Triangulation • Proximity • Scene analysis • Location sensing systems • Properties • Examples • Challenges • Advantages and disadvantages of each

  12. Location sensing, cont. • Properties of location systems • Choosing the right one for a specific application • Limitations of specific systems • Implications of location data for privacy

  13. Privacy • Initial entitlement: • Allocation of property rights • Who should get the initial right to control the information generated by location sensing? • Coercion and choice: • If you want discount you will get the technology. • Societal overrides: • When does society, regardless of your preference, get access to the data anyway?

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