Wireless

What is the primary reason that OFDM (802.11a) radios cannot communicate with ERP (802.11g) radios?

802.11a operates at 5GHz, and 802.11g operates at 2.4 GHz.

Which 802.11 draft amendments may provide the throughput of 1 Mbps or higher?

802.11ac 802.11ad

Which 802.11 amendment defines wireless mesh networking mechanisms?

802.11s

Which of the following are valid ISM bands?

902-928 MHz 2.4-2.5 GHz 5.725-5.875 GHz

The 802.11-2007 standard defines which two technologies for quality of service (QoS) in a WLAN?

EDCA Hybrid Coordination Function Controlled Channel Access

As defined by the 802.11-2007 standard, which equipment is compatible?

ERP and HR-DSS 802.11a and 802.11h DSS and HR-DSS

An ERP (802.11g) network mandates support for which two spread spectrum technologies?

ERP-OFDM ERP-DSSS/CCK

The highest RF signal strength that is transmitted from an antenna is known as what?

Equivalent isotropically radiated power

What are some of the possible negative effects of an impedence mismatch?

Erratic signal strength Decreased signal amplitude Amplifier/transmitter failure

When implementing an 802.1X/EAP RSN network with a VoWiFi solution, what is needed to avoid latency issues during roaming?

Fast BSS transition

Which of the following are valid calculations when using the rule of 10s and 3s?

For every 3dB gain (relative), double the absolute power of (mW) For every 10 dB of loss (relative) divide the absolute power (mW) by a factor of 10

In a normal wireless bridged network, the greatest loss of signal is caused by what component?

Free space path loss

When determining the mounting height of a long-distance point-to-point antenna, which of the following needs to be considered?

Frequency Distance Earth bulge RF line of sight

Which three properties are interrelated?

Frequency, wavelength, and the speed of light

To establish a 4-mile point-to-point bridge link in the 2.4GHz ISM band, what factors should be taken into consideration?

Fresnal zone with 40 percentage or less blockage Proper choice of semidirectional antennas

A standard measurement of frequency is called what?

Herz

The 802.11-2007 standard was created by which organization?

IEEE

What is the definition of the horizontal beamwidth of an antenna?

The distance between the two -3dB power points on the horizontal axis, measure in degrees.

When a long-distance point-to-point link is installed, earth bulge should be considered beyond what distance?

7 miles

Which 802.11 radio technologies are most impacted by destructive effects of multipath?

802.11a,b,g

802.11 wireless bridge links are typically associated with which network architecture layer?

Distribution

What RF component is responsible for generating the AC signal?

Transmitter

The original 802.11 standard quires which data rates?

1 and 2 Mbps

The 802.11-2007 standard using an ERP-DSSS/CCK radio supports which data rates?

1,2,5,5 and 11 Mbps

When multiple RF signals arrive at a receiver at the same time and are _____ with the primary wave, the result can be ______ of primary signal.

180 degrees out of phase, cancellation

802.11n can transmit in which frequency bands?

2.4 - 2.4835 GHz 5.47-5.725 GHz 5.15-5.25 GHz

What is the frequency of an RF signal that cycles 2.4 million times per second?

2.4 MHz

A wireless bridge is configured to transmit at 100 mW. The antenna cable is and connectors produce a 3dB loss and are connected to a 16 dBi antenna. What is the EIRP?

2000 mW

23 dBm is equal to how many mW

200mW

A WLAN transmitter that emits a 100mW signal is connected to a cable with a 3 dB loss. If the cable is connected an antenna with 7 dBi of gain, what is the EIRP at the antenna element?

250mW

A wave is divided into degrees. How many degrees make up a complete wave?

360

2 dBd is equal to how many dBi

4.14

The fresnal zone should not be blocked by more than what percentage to maintain a reliable communications link?

40 percent

A WLAN transmitter that emits a 400mW signal is connected to a cable with 9 dB loss. If the cable is connected to an antenna with 19 dBi of gain, what is the EIRP

4W

Which of the following are valid UNII bands?

5.150-5.250 GHz 5.47-5.725 GHz 5.725-5.825 GHz

In the UNII-1 band, what is the center frequency of channel 40?

5.2 GHz

Maximum data rates of _____ are permitted using OFDM radios.

54Mbps

An 802.11a radio card can transmit on _____ frequency and uses _____ spread spectrum technology

5GHz, OFDM

To double the distance of a signal, the EIRP must be increased by how many dBs?

6 dB

Which are the required data rates of an OFDM station?

6,12, and 24 Mbps

What two technologies are used to prevent 802.11 radios from interfering with radar transmissions at 5GHz?

Dynamic frequency selection Transmit power control

Which keying method is most susceptible to interference from noise?

ASK

802.11 technology is typically deployed at which fundamental layer of network architecture

Access

The signal between the transceiver and the antenna will be reduced by which of the following methods?

Adding an attenuator Increasing the length of the cable Using a cheaper-quality cable

Which of the following wireless communications parameters and usage are typically governed by local regulatory authority?

All

Amplifiers can be purchased with which of the following features?

All of them

Which are technologies are used in the 2.4 GHz ISM band?

All of them

Which of these propagation behaviors can result in multipath?

All of them

The height or power of a wave is known as what?

Amplitude

Which wave properties can be modulated to encode data?

Amplitude Frequency Phase

Using knowledge of RF characteristics and behaviors, which two options should a WLAN engineer be most concerned about during an indoor site survey?

Brick walls, User density

A robust security network (RSN) requires the use of which security mechanism?

CCMP/AES 802.1x

A modulated signal capable of carrying data is known as what?

Carrier Signal

What type of signal is required to carry data?

Carrier signal

Which types of devices were defined in a legacy 802.11 WLAN network?

Clause 15 DSS Caluse 16 IR Clause 14 FHSS

Which layers of the OSI model are referenced in the 802.11 standard?

Data-link Physical

Which term is used to describe a time differential between a primary signal and a reflected signal arriving at a receiver?

Delay spread

When a RF signal bends around an object, this propagation is known as what?

Diffaction

The size of a fresnal zone is controlled by what factors?

Distance Frequency

When calculating the link budget and system operating margin of a point-to-point outdoor WLAN bridge link, what factors should be taken into account?

Distance Receive sensitivity Transmit amplitude Cable loss Frequency

The sum of all the components from the transmitter to the antenna including the antenna, is known as what?

IR Intentional radiator

A point source that radiates RF signal equally in all direction is known as what?

Isotropic radiator

Which sublayer of the OSI model's Data-Link layer is used for communication between 802.11 radios?

MAC

What are some objects or materials that are common causes of reflection?

Metal Asphalt road Lake

Which organization is responsible for enforcing maximum transmit power rules in an unlimited frequency band?

None of the above

What are the security options available as defined in the original IEEE Std. 802.11-1999

Open System authentication Shared Key authentication WEP

What is the best example of a time domain tool that could be used by an RF engineer?

Oscilloscope

The radius of the second Fresnel zone is

Out of phase with the point source Larger than the first fresnal zone

Which antennas are highly directional?

Parabolic dish Grid

The IEEE 802.11-2007 standard defines communcation mechanisms at which layers of the OSI model?

Physical Data-link

During a site survey in a manufacturing plant, the WLAN engineer determines that the noise floor is extremely high because of all the machinery that is operating in the plant. The engineer is worried about a low SNR and poor performance due to the high noise floor. What is a suggested best practice to deal with this scenario?

Plan for coverage cells with a 5dB fade margin

Semidirectional antennas are often used for which of the following purposes?

Providing short-distance point-to-point communications Providing unidirectional coverage from an access point to clients in an indoor environment Reducing reflections and the negative effects of multipath

Which of the following statements is true about amplification?

RF amplifiers require an outside power source Antennas are passive gain amplifiers that focus the energy of a signal in one direction. Signal strength may passively increase because of multipath upfade

Which of the following devices produce active gain?

RF transceiver RF amplifier

Which value should not be used to compare wireless network cards manufactured by different WLAN vendors?

RSSI

Which R.F behavior best describes a signal striking a medium and bending in a different direction?

Refraction

WLAN vendors use RSSI threshold to trigger which radio card behaviors?

Roaming Dynamic rate switching

Which behavior can be described as an RF signal encountering a chain link fence, causing the signal to bounce in multiple directions?

Scatter

Which of the following can cause refraction of an RF signal traveling through it?

Shift in air temperature Change in air pressure Humidity Smog

While aligning a directional antenna, you notice the signal drops as you turn the antenna away from the other antenna, but then increases a little. This increase in signal is caused by what?

Side lobe.

Received signal strength indicator(RSSI) metrics are used by 802.11 radios to define which RF characteristics?

Signal strength

What is an example of a frequency domain tool that could be used by an RF engineer?

Spectrum analyzer

A network administrator replaced some coaxial cabling used in an outdoor bridge deployment after water damaged the cabling. After replacing the cabling, the network administrator noticed that the EIRP increased drastically and is possibly violating the maximum EIRP power regulation mandate. What are the possible causes of the increased amplitude?

The administrator installed a shorter cable. The administrator installed a high-grade cable.

dBi is a measure of what?

The signal increased caused by the antenna

Which of the following is true about antenna density?

The transceiver samples both antennas and chooses the best received signal from one antenna. Transceivers can transmit from only one of the antennas at a time

What are the disadvantages of using unlicensed frequency bands for RF transmissions?

There is no additional financial cost Anyone can use a frequency band

Which of the following is true about cables?

They cause impedance of the signal They add loss to the signal

The azimuth chart represents a view of an antenna's radiation pattern from which direction?

Top

Lightning arrestors will defend against which of the following?

Transient currents

What is the channel and band of a Wi-Fi transmission whose center frequency is 5300 GHz

UNII-2 channel 60

What are some results of multipath interference?

Upfade Excessive retransmission

The ratio between the maximum peak voltage and minimum voltage on a line is known as what?

VSWR

The Wi-Fi alliance is responsible for which of the following programs?

Voice Personal WMM-PS

The 802.11u-2011 amendment is also known as

WIEN

The Wi-Fi Alliance is responsible for which of the following certification programs?

WMM

Select the absolute units of power

Watt Milliwatt dBm

What term best defines the linear distance traveled in one positive-to-negative-topositive oscillation of an electromagnetic signal?

Wavelength

Which of the following statements are true?

When downfade occurs, the final signal will never be stronger than the original transmitted signal. When upfade occurs, the final received signal will never be stronger than the original transmitted signal.

What organization ensures interoperability of WLAN products?

Wi-Fi Alliance

Select units of comparison(relative)

dBi Decibel dBd Bel