Lecture 2

Classify the Cricket location system according to the taxonomy of the “Positioning” reading (from Location-Based Services, Chapter 6) shown in Figure 6.2 on page 127. Is it terminal-based or network-based? Is it integrated or stand-alone? Explain each answer in one short sentence each.

Lecture 3

Provide a short answer for each of the following questions:

(1) How does a GPS receiver distinguish between the signals received from different satellites?

(2) In 1-2 sentences, describe how carrier phase tracking can be used to improve the localization error of GPS.

Lecture 4

Provide a short answer for each of the following questions:

(1) In WiTrack, how does FMCW compute the time of flight?

(2) In WiTrack, what is the difference between static and dynamic multipath?

(3) List 2 advantages and 2 disadvantages for WiTrack over RADAR.

Lecture 5

In your own words (don’t copy from the paper), in one or two sentences, explain what the “gateway problem” is, as illustrated by the paper “The Internet of Things Has a Gateway Problem”.

Lecture 6

Suppose we want to send data from node S to node T in a multi-hop wireless network. The probability of successfully receiving an ACK for a packet sent from S to T directly is q. The other choice is to use an intermediate node, N; the probability of successfully receiving an ACK for a packet from S to N is p, the same as the probability of successfully receiving an ACK for a packet sent from N to T. Using ETX, under what conditions would the direct link from S to T be preferred to the path S — N — T?

Lecture 7

Describe two settings in which inertial sensing can be superior to/preferred over GPS for navigation applications.

Lecture 8

A simple method to detect potholes would be to look at time windows during which the absolute magnitude of the acceleration vector is above some threshold. This will lead to a number of false positives, as described in the paper. After reading the paper, list two sources of such false positives, and how the paper proposes to address them.

Lecture 9

Please read the vital radio paper and answer the following questions:

(1) We learned that WiTrack's accuracy is about 10cm. Further, we learned that the resolution of FMCW is C/2B, where C is the speed of light and B is the bandwidth. VitalRadio uses the same FMCW radio that WiTrack uses. So how is it possible for VitalRadio to measure movements as small as the chest inhale-exhale motion?

(2) VitalRadio can measure sub-centimeter motion. Can one use that technique to improve trajectory resolution in WiTrack to localize a person to within sub-centimeter accuracy? Explain your answer.

Lecture 10

Summarize in 1-2 sentences how the type of aggregation function used in the query affects the communication efficiency of TAG.

Lecture 11

Please read the RFind paper and answer the following questions:

(1) Since RFIDs are battery-free, where do they obtain the energy to power up and communicate?

(2) Give two reasons why RFind needs the two-excitation technique to achieve large bandwidth (i.e., why can’t it simply perform frequency hopping within the ISM band).

Lecture 12

Explain the problem that CTrack solves: i.e., what are the inputs to CTrack, and what are the outputs?

Lecture 13

In the paper by Biagioni and Eriksson, to find road centerlines, the authors develop a new gray-scale skeletonization method. This method iterates through binary skeletonization starting from the highest density level and proceeding downwards in density levels. Why does it produce a better result than using binary skeletonization once at a low density level?

Lecture 14

1) How does Farmbeats combine aerial imagery with sparse sensor data to generate a fine-grained sensor map?

2) What are the two constraints that Farmbeats needs to satisfy for duty cycling its IoT operation?

Lecture 15

(1) Alice and Ben have invited a few colleagues to an important private meeting. They are however worried that one of their colleagues may use his cell phone to record the conversation at the meeting. Alice claims that she and Ben can use the technique in the paper to prevent such recording. Is Alice right? Explain your answer.

(2) List two advantages for the technique in the paper in comparison with past work on near-ultrasound.