Tema 4.1 - WiFi basics

The 802.11 standard was designed for:

• WWANs

• WMANs

• WLANs

• WPANs

The maximum transmission rate for the 802.11a and 802.11g standard extensions is:

• 2 Mbit/s.

• 11 Mbit/s.

• 54 Mbit/s.

• 300 Mbit/s.

In most countries, 802.11 devices use the 2.4GHz ISM band by selecting among:

• 13 channels, each with a bandwidth of 22MHz.

• 11 channels, each with a bandwidth of 22MHz.

• 13 channels, each with a bandwidth of 44MHz.

• 11 channels, each with a bandwidth of 44MHz.

Which of the following effects in used by a parabolic antenna to improve the reception quality of a signal:

• Absorption.

• Reflection.

• Diffraction.

• None of the former.

This radiation pattern corresponds to:

• An omnidireccional antenna.

• A parabolic antenna.

• A Yagi antenna.

• None of the former.

A power of 1W can be represented as:

• 1 dBm

• 10 dBm

• 30 dBm

• 1000 dBm

In an infrastructure-based 802.11 network, the BSSID is:

• The MAC address of the access point creating the BSS.

• The MAC address of the terminal connected to the BSS.

• The name defined for the network.

• The key used to secure the network.

Concerning the differences between CSMA/CD and CSMA/CA, choose the correct option:

• CSMA/CA introduces backoff, ACK, RTS/CTS and PCF.

• CSMA/CA introduces backoff, ACK and PCF.

• CSMA/CA introduces ACK, RTS/CTS and polling.

• CSMA/CA introduces ACK and RTS/CTS.

In 802.11, the time interval (Inter Frame Spacing) reserved solely for access points is:

• SIFS

• PIFS

• DIFS

• EIFS

Regarding the RTS/CTS mechanism:

• It is activated for frames considered “large”, and it is useful to solve the hidden terminal problem.

• It is activated for frames considered “large”, and it is useful to solve the exposed terminal problem.

• It is activated for all the frames in the presence of hidden nodes.

• It is activated for all the frames in the presence of hidden and exposed nodes.