Learning Objectives

After successfully completing this section, you should be able to

  1. explain in technical terms what wireless networks are and how they work.
  2. explain the IEEE standards that are the basis for today’s wireless networks.
  3. describe the important characteristics of Wi-Fi networks.
  4. explain the essential elements of wireless networks and the roles they play.

Learning Tasks

Required:

  1. Watch the slideshow for this section.
  2. Study the following sections of the textbook:

7.1 Introduction
7.2 Wireless Links and Network Characteristics
7.3 Wi-Fi: 802.11 Wireless LANs

Terms and Topics

Section 1 – Wireless Networking

Wireless networks
Wireless hosts
Wireless communication links
Base station
Cell towers
Access points
Infrastructure mode (of wireless networks)
Ad hoc wireless networks
Handoff
Wireless network infrastructure
Wireless mesh networks
Mobile ad hoc network (MANETs)
Vehicular ad hoc networks (VANETs)
Characteristics of wireless networks
Differences between wired and wireless networks
Multipath propagation
Signal-to-noise ratio (SNR)
Hidden terminal problem in wireless networks
Code division multiple access (CDMA)
Chipping rate (of CDMA scheme)
Wi-Fi
IEEE 802.11 wireless LAN
The IEEE 802.11 architecture
Base station
Access point
Infrastructure wireless LANs
Channels and association
Service set identifier (SSID)

Clear to send (CTS)
Using 802.11 as a point-to-point link
IEEE 802.11 frame structure
Mobility in the same IP subnet
Advanced features of 802.11
Rate adaptation
Power management
Bluetooth and Zigbee as personal area networks
IEEE 802.15.1 for Bluetooth networks
Frequency-hopping spread spectrum (FHSS)
Wi-Fi jungle
Beacon frames Passive (channel) scanning
Active (channel) scanning
CSMA with collision avoidance (CSMA/CA)
CSMA/CA – the 802.11 MAC protocol
Link-layer acknowledgement
Short inter-frame spacing (SIFS)
Distributed inter-frame space (DIFS)
Dealing with a hidden terminal with RTS and CTS
Request to send (RTS)Piconet
Master device in a Bluetooth network
Slave device in a Bluetooth network
Parked device in a Bluetooth network
WiMAX – another 4G wireless technology

Leading Questions

  1. What electronic devices can be wireless hosts in wireless networks?
  2. What is a wireless communication link?
  3. What are the relationships between base stations and access points?
  4. What are the differences between infrastructure mode wireless networks and ad hoc wireless networks?
  5. What are the parts of a wireless network infrastructure?
  6. Compare and contrast wired networks and wireless networks, emphasizing their differences.
  7. How does multipath propagation occur?
  8. What is the so-called hidden terminal problem?
  9. What is the “chipping rate”?
  10. How does CDMA work in wireless networks?
  11. How does CDMA encode and decode data in wireless networks?
  12. What IEEE standard is used for wireless networking?
  13. What is a basic service set (BSS)?
  14. What do SSID and Wi-Fi stand for?
  15. What is a distribution system in wireless networking?
  16. What is CSMA/CA?
  17. What are DIFS and SIFS?
  18. Why doesn’t the IEEE 802.11 MAC protocol implement collision detection?
  19. In an IEEE 802.11 wireless network, why can hidden terminals be problematic? How does the standard deal with the problem? What format does an IEEE 802.11 standard use for its frame?
  20. In order to accommodate mobile users, what considerations should be taken when designing the network layer?
  21. From the standpoint of network layers, how mobile is a user?
  22. How important is the mobile node’s address?
  23. What supporting wired infrastructure is available for supporting wireless connections?
  24. What is ad hoc networking?
  25. What issues are involved in allowing a mobile user to maintain ongoing connections while moving between networks?
  26. What do the terms home network, home agent, foreign (or visited) network, foreign agent, and correspondent mean?
  27. Why should all traffic addressed to a mobile node’s permanent address be routed to the foreign network when the node is a resident of a foreign network? How can this be done?
  28. What roles does a foreign agent play?
  29. What is a care-of-address?
  30. What is a home address? What is a foreign address?
  31. How does indirect routing work?
  32. How does the mobile node to foreign agent protocol work?
  33. What problem does the indirect routing approach suffer from?
  34. How does the direct routing approach work?
  35. What is a correspondent agent in the direct routing approach?
  36. What is mobile IP? Which standard defines mobile IP?
  37. What are the three main pieces of the mobile IP standard?
  38. What is done in the process of agent discovery?
  39. What is done in the process of agent advertisement?
  40. What does agent solicitation do?
  41. What is the format of an ICMP router discovery message with mobility agent advertisement?
  42. According to the mobile IP standard, how does a mobile node register its care-of address (COA) with its home agent?
  43. How do wireless stations move seamlessly from one BBS to another while maintaining ongoing TCP sessions?
  44. What are the main features of 802.15 wireless networks?
  45. How is a Bluetooth network related to 802.15 wireless networks?
  46. What do FHSS and PSTN stand for?