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1.
Learning
objectives:
a)
Understand the motivation of link estimation protocols and the time
varying nature of a wireless channel;
b)
Understand the metric of ETX;
c)
Understand the four-bit link estimation;
d)
Understand the impact of link estimation on representative TinyOS
network protocols.
2.
Prerequisites:
Module 2,
plus a). Basic concepts of wireless communications; b). Basic concepts of
computer networks.
3.
Module
description:
In this module, we first introduce why wireless
link estimation is necessary by showing details of the time varying nature
of a wireless channel. The data we use come from the experiments with a real
world WSN, which vividly demonstrate the relevant features of a wireless
link.
We then introduce state-of-the-art link estimation techniques. First, we
focus on ETX . Expected Transmission Count, whose purpose is to choose
routes with high end-to-end throughout and find paths with the fewest
expected number of transmissions. Secondly, we focus on four-bit wireless link
estimation. In this estimation, information from the physical layer, the
data link layer, and the network layer are all integrated to estimate the
quality of a link.
4.
Tools
utilized:
Micaz motes and TelosB motes are used as the
example hardware platforms to illustrate the motivation of link estimation
protocols and how to perform wireless link estimations.
5.
Requirements:
Students are required to read related papers and
understand presented ideas. After these steps, students are then encouraged
to go through TinyOS CVS tree to have a deeper understanding of presented
protocols.
6.
Assignments
and Hands-on projects:
There is no programming project for this module.
+ Assignment
7.
Level of
difficulty: This module is
classified as a module of intermediate difficulty.
8.
Grading/evaluation
criteria: Check
for the correctness of the answers in the assignments.
9.
PowerPoint
slides: link_estimation.ppt
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