Lecture 23: Wireless Networks
The mobility provided by wireless networks has made a huge difference in the lives of most citizens of the internet. However, several challenges have to be overcome by a wireless link layer to make that promise into a reality. Primary among them is the lack of collision detection due to receiver shutdown during transmission. The hidden terminal problem also means that collisions are not apparent to all hosts on a link. This lecture will examine the collision avoidance mechanisms that are key to 802.11 wireless protocols.
Lesson Objectives
By the end of this lesson, the student will be able to:
- explain the challenges of a wireless subnet, including those caused by range limits, mobility, receiver shutdown, noise, multi-path, hidden terminal, and exposed terminal problems.
- describe the CSMA/CA algorithm and how it helps overcomes some of the wireless challenges.
- describe the use of channel reservations to avoid collisions.
- explain some features of the 802.11 standard (do not memorize features of the variants). Such features include operating modes, security, frame format, power management and rate adaptation.
Reading
- KR 7.1 - 7.3