Chapter 7

Question 1

Path Loss

Answer 1

A wireless signal weakens as the distance between the sender and receiver increases.

Question 2

Interference from other sources

Answer 2

Wireless signals can be distributed by other signals.

Question 3

Multi-path Propagation

Answer 3

Wireless signals can reflect off objects, causing multiple copies of the signal to arrive at different times, potentially interfering with each other (ex. Echo)

Question 4

Signal-to-Noise Ratio (SNR)

Answer 4

A high SNR means a clearer conversation, just like a strong signal with minimal interference leads to better wireless communication quality.

Question 5

But Error Rate (BER)

Answer 5

If you often mishear words in a conversation, it’s similar to but error rate, where data is frequently corrupted during transmission.

Question 6

Wireless Link Types

Answer 6

1. Single-Hop, Infrastructure-Based
2. Single-Hop, Infrastructure-Less
3. Multi-Hop, Infrastructure-Based
4. Multi-Hop, Infrastructure-Less

Question 7

Single-Hop, Infrastructure-Based

Answer 7

Devices communicate through a central base station (to extend their range)

Question 8

Single-Hop, Infrastructure-Less

Answer 8

Devices communicate directly without any intermediate infrastructure.

Question 9

Multi-Hop, Infrastructure-Based

Answer 9

Devices communicate through multiple intermediate nodes and a central infrastructure.

Question 10

Multi-Hop, Infrastructure-Less

Answer 10

Devices related to data through multiple nodes without any central infrastructure.

Question 11

Cellular Network Structure

Answer 11

The coverage area is divided into hexagonal cells, each with its own base station (ex. Honeycomb)

Question 12

Handoff

Answer 12

As you move from one cell to the other, your connection is handed off to the next cell’s base station.

Question 13

Latency

Answer 13

Like the time it takes for a car to travel from one point to another Lower latency means quicker data transmission.

Question 14

Jitter

Answer 14

Variation in travel time, similar to unpredictable traffic conditions that cause variable delays.

Question 15

Wireless Access Point (AP)

Answer 15

Helps devices communicate more effectively by amplifying their “voices” (signals) so everyone can hear (ex. Megaphone)

Question 16

Stations (STAs)

Answer 16

Devices that communicate over WiFi networks. Each person in the room represents a station.

Question 17

Wireless Communication Process - Association

Answer 17

When a device wants to join a network, it sends an association request to the AP. The AP responds with an association response, either allowing or not.

Question 18

Data Transmission

Answer 18

Once associated, devices can send and receive data through the AP.

Question 19

Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA)

Answer 19

In a wireless network, it’s important to avoid having two devices transmit at the same time to prevent collisions.

Question 20

Carrier Sense

Answer 20

Before speaking (transmitting data), a device listens to see if anyone else is already “talking”.

Question 21

Collision Avoidance

Answer 21

If room is quiet, device waits a short, random period before speaking, to avoid starting at the same time as someone else.

Question 22

MAC Header

Answer 22

Includes the source and destination addresses.

Question 23

Payload

Answer 23

Actual data being sent.

Question 24

Trailer

Answer 24

Contains error-checking information to ensure the data was received correctly (similar to repeating a sentence to check for mistakes)

Question 25

Wired Equivalent Privacy (WEP)

Answer 25

An older, less secure method to protect data.

Question 26

WiFi Protected Access (WPA)

Answer 26

More secure methods to protect data.

Question 27

Roaming

Answer 27

When a device moves out of range of one AP and into the range of another, it needs to re associate with the new AP.

Question 28

Roaming

Answer 28

When a device moves out of range of one AP and into the range of another, it needs to re associate with the new AP.