Chapter 9 WLAN Troubleshooting Objectives: Multipath and Hidden Node

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What is the term used to describe when multipath causes an RF signal to gain strength?

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How can the occurrence of multipath be detected using link budget calculation?

Look for an output power level that should work but does not

What is one way to determine that multipath is occurring during RF signal transmission?

Detection of RF coverage holes in a site survey

What is the purpose of antenna diversity in the context of multipath issues?

Compensating for multipath by using multiple antennas, inputs, and receivers Signup and view all the answers

What condition occurs when reflected waves arrive at the receiver out-of-phase with the main wave, cancelling out the main signal?

Nulling Signup and view all the answers

What types of obstacles more easily reflect RF waves, contributing to multipath issues?

Metal blinds, metal roofs, etc. Signup and view all the answers

What is multipath in the context of RF wave propagation?

Multipath is defined as the composition of a primary signal plus duplicate or echoed wave fronts caused by reflections of waves off objects between the transmitter and receiver. Signup and view all the answers

What is delay spread in the context of multipath?

Delay spread is the delay between the instant that the main signal arrives and the instant that the last reflected signal arrives. Signup and view all the answers

How can multipath propagation affect the signal amplitude at the receiver?

Reflected waves, out-of-phase with the main wave, can cause decreased signal amplitude at the receiver. Signup and view all the answers

What term is used to describe corrupted signals due to multipath?

Corrupted signals due to multipath are a result of the same phenomena that cause decreased amplitude, but to a greater degree. Signup and view all the answers

Explain the concept of hidden node in wireless communication.

A hidden node refers to a node that is out of range of one or more nodes, causing interference in wireless communication. Signup and view all the answers

What is the importance of identifying proper troubleshooting methods in WLAN?

Identifying proper troubleshooting methods is crucial for resolving issues related to multipath, hidden nodes, and other WLAN problems effectively. Signup and view all the answers

What action should be taken to implement RTS/CTS?

Decrease the RTS/CTS threshold on a client Signup and view all the answers

When should you suspect a hidden node is the problem?

If throughput improves when RTS/CTS is enabled. Signup and view all the answers

What is the expected change in throughput in a network with no hidden nodes when RTS/CTS is enabled?

Decrease in throughput Signup and view all the answers

How can hidden nodes be located?

Manual search usually involving trial-and-error Signup and view all the answers

What are some remedies for hidden node issues?

Use RTS/CTS, Increase power to the nodes, Move the node, Remove obstacles Signup and view all the answers

What logic does transmit diversity require?

Different logic than receive sensitivity Signup and view all the answers

How does an Access Point (AP) determine which antenna has the highest signal strength?

By listening to one antenna, then the other Signup and view all the answers

What is the Hidden Node problem in a WLAN?

A situation where at least one node cannot hear one or more other nodes connected to the WLAN Signup and view all the answers

How can the Hidden Node problem cause degraded throughput in a WLAN?

By causing collisions Signup and view all the answers

What are the 3 main ways in which the Hidden Node problem can occur?

Obstacle between stations, stations on opposite sides of AP, one node in 'null' relative to another due to multipath interference Signup and view all the answers

How can you diagnose the Hidden Node problem using a protocol analyzer?

High levels of corrupted frames near the AP, lots of retransmissions near an end station affected by the hidden node Signup and view all the answers