Midterm Practice problems for Tech 165
iBeacon
a technology that apps can use to determine a user's location
The Unlicensed National Information Infrastructure (U-NII) band operates in the-----frequency band. a.2.4 GHz b.33 GHz c. 5GHz d.16 KHz
c. 5GHz
Between the transmitting antenna and the receiving antenna, a signal will always be subject to _________________.
free space loss
Fresnel zone
is an elliptical area between two directional antennas. When setting up a wireless link in this way, maintaining a reliable connection requires that no more than 40 percent of the Fresnel zone be blocked by obstructions.
The result of using a PN code is that ________.
it spreads the signal over a wider range of frequencies
Each of the following is a type of RF filter except-----
passband
What are the two layers of OSI model
physical and data link
RFID
radio frequency identification, similar to barcodes
Challenges of wireless networking
radio signal interference, security, and health risks.
Antennas are----devices.
reciprocal
IEEE 802.11s
An IEEE 802.11 amendment that enables APs to communicate with each other over the wireless medium. Prior to 802.11s, the standard only allowed APs to communicate with each other over the Ethernet medium and only for the purpose of disassociation of roaming mobile devices.
IEEE 802.11ad
An IEEE 802.11 amendment that expands the standard to work in the 60 GHz portion of the ISM band and can reach speeds of up to 10 Gbps at distances of no more than 2 meters, due to signal attenuation that can be caused by molecules of oxygen in the air.
IEEE 802.11n
An IEEE 802.11 amendment that increases the theoretical data rate up to 600 Mbps. Note than no 802.11n compatible equipment has ever been manufactured that achieves this rate. The maximum data rate achievable with 802.11n today is 450 Mbps
IEEE 802.11n
An IEEE 802.11 amendment that increases the theoretical data rate up to 600 Mbps. Note than no 802.11n compatible equipment has ever been manufactured that achieves this rate. The maximum data rate achievable with 802.11n today is 450 Mbps.
IEEE 802.11ac
An IEEE 802.11 amendment that works exclusively in the 5 GHz band and can achieve data rates of up to 6.9 Gbps by supporting channel bandwidths of 80 and 160 MHz.
Digital Convergence
the use of a single unifying device to handle media, Internet, entertainment, and telephony needs. For example, watching TV and access on-demand movies
What term refers to the combining of voice, video and text-processingand access to multiple network platforms from a single device?
Digital Convergence
Which type of modulation requires less power to transmit?
Digital Modulation
What is the standard that establishes the telecommunications?
IEEE
Which range of the electromagnetic spectrum is less susceptible to interference from sources of visible light?----
Infrared
RF Propagation
The way that radio waves propagate, or move, between the transmitter and the receiver through the atmosphere of our planet depends on the frequency of the signal. RF waves are classified in three groups, as shown in Table 4-3. Ground waves follow the curvature of the Earth. Sky waves bounce between the ionosphere and the surface of the Earth. RF waves transmitted in frequencies between 30 MHz and 300 GHz require a line-of-sight path between the transmitter and the receiver antennas.
Amplifiers increase the amplitude of RF signal True or False
True
Mixers combine two radio frequency inputs to create a single input True or False
True
Radiation patterns is measurement signal radiates from the antenna True or False
True
If the passband first line is 4,500 hz and 3,000 hz what is the output 3,000 hz
3000 hz
Point-to-Multipoint Links
A link in which one central site uses an omnidirectional antenna to transmit to multiple remote sites, which may use omnidirectional antennas or directional antennas to maximize the distance and the quality of the signal.
cellular network
A network that can be used when a wireless network must cover a wide area. The network is made up of cells, each controlled by a base station. Also called a cellular WAN. It has the ability go long distances.
Smart Antenna
A new type of antenna that uses a signal processor and an array of narrow beam elements to track the user and send most of the RF energy in the direction of the mobile receiver in order to prevent interference and avoid wasting RF energy. There are two types of smart antennas, switched-beam and adaptive or phased array antenna.
Active antenna
A passive antenna with an amplifier built-in.
A(n)------ transmission uses spread spectrum technology and unique spreading codes for each user.
CDMA
A(n)------transmission uses spread spectrum technology and unique spreading codes for each user.
CDMA
Disadvantages of standards
Can be a threat to industries in large countries- Although standards are intended to create unity• They can have the opposite effect• Many experts agree that the advantages ofstandards far outweigh the disadvantages- Standards are vital for the telecommunicationsindustry
What are the primary applications for smart antenna?
Cellular Telephony WifiMax
What is the definition of gain?
Gain is the ratio of the output signal. Gain has no unit of measure. Also a increase in the power level
Shape & Size of Antenna
-The direction of the electromagnetic field -The power with which the antenna must transmit or how sensitive it needs to be to receive very weak signals -The frequency that the antenna is designed to transmit and receive
What is the definition of decibels?
A ratio between two signal levels.
Loss
A relative measure of decrease in a signal's power level.
WiGig
A specification for connecting computers, communication, and entertainment devices over short ranges, using the 60 GHz band at multi-gigabit speeds, developed by an alliance of companies.
One-Dimensional Antenna
A straight length of wire or metal connected to a transmitter at one end.
Beamforming
A technique employed by 802.11n devices that uses multiple radios and antennas to virtually direct the transmission to the location of a device, similar to the way that phased array antennas work.
Antenna Diversity
A technique that uses two antennas to improve the range of 802.11 and transmits a signal through the antenna that received the strongest signal during the last transmission.
NFC
A technology similar and sometimes compatible with RFID that can store data that can be used to configure and activate a connection between two devices over Bluetooth or Wi-Fi. NFC tags are similar to RFID tags and can also store web addresses and may contain commands to be executed by a smartphone or tablet, such as opening a web browser and automatically entering an address.
MIMO (multiple input-multiple output)
A technology that uses multiple antennas (usually three or four) and reflected signals (multipath reflections) to extend the range of the WLAN by attempting to correctly decode a frame from multiple copies of it received at different times.
Spatial Multiplexing
A transmission technique that uses multiple radios and multiple antennas to send different parts of the same message simultaneously, thus increasing the data rate.
What are the advantages of standards?
Advantages- Guarantee device interoperability- Create competition• Competition results in lower costs for consumers and improvements in products• Competition also results in lower costs for manufacturers- Help consumers protect their investment in equipment.
IEEE 802.11r
An IEEE 802.11 amendment aimed primarily at reducing the reassociation time in an ESS to less than 50 ms, to prevent breaks that reduce the quality of voice calls. It also enables mobile devices to communicate with APs within range, on different channels, ahead of reassociating with one of them, to determine whether they have enough processing resources to handle an ongoing voice call over the WLAN.
IEEE 802.11a
An IEEE 802.11 amendment developed in 1999, a standard for WLAN transmissions at speeds of up to 54 Mbps.
IEEE 802.11e
An IEEE 802.11 amendment for WLAN applications that implements QoS for WLANs and provides for improvements in their capabilities and efficiency.
IEEE 802.11g
An IEEE 802.11 amendment that allows for WLAN transmissions at speeds of up to 54 Mbps using the ISM band.
two-dimensional antenna
An antenna, such as a dish or patch, that has both height and width. In omnidirectional antennas, the thickness of the pole or wire is not considered a second dimension.
Antenna Polarization
An indication of the horizontal or vertical orientation of the sine waves leaving an antenna.
Which type of transmission is used when human voice is modulateddirectly onto a carrier wave?
Analog
Zigbee
Low-power wireless communications open source protocol used primarily for home automation. ZigBee uses radio frequencies in the 2.4 GHz band and a mesh topology and it is based 802.15.4 for IEEE
What are the advantages of wireless networking?
Mobility,Easier less expensive installation, increase reliability, and Disaster Recovery.
--------divides the bandwidth of the frequency into several narrower frequencies. Each user then transmits using its own narrower frequency channel.
OFDM
What are the OSI layers?
Physical, Data Link, Network, Transport, Session, Presentation, Application
In the context of WPAN security, Banking and Electronic FundsTransactions use a unique security code, or key, provided by acertificate authority to verify the authenticity of a user. What is thissecurity protocol called? a.Access Control List (ACL) b.Virtual Private Network (VPN) c.Message Authentication Code(MAC) d.Public Key Infrastructure (PKI)
Public Key Infrastructure (PKI)
What are the main components of a wireless Access Point device?
Radio transmitter/receiverModule Antenna RJ-45 wired network interface port
passive antenna
The most common type of antenna. Passive antennas can only radiate a signal with the same amount of energy that appears at the antenna connector.
Point-to-Point Links
The most reliable link between two antenna sites using directional antennas to maximize the distance and the signal quality.
Which of the following divides the bandwidth of the frequency channel into several time slots?
TDMA
Satellite networks
Used to transmit data over very long distance and Companies that have offices and stores in locations where a wired connection to the Internet is not easily available can use satellite communications to connect to the Internet. Isolated communities, away from the major cities in many countries, frequently make use of satellite communications for Internet access. International airlines offer Wi-Fi con- nections in flight and use a satellite connection to enable travelers to access the Internet.
Radiotelephony or radio travels in waves known as-----waves a. electromagnetic b. analog c. magnetic d. electrical
a. electromagnetic
Most Bluetooth devices can transmit data at a maximum rates of 1-3Mbps at distance of up to 33 feet (10 meters) a.True b.False
a.True
An 802.11 wireless NIC, when configured to communicate with a wired network, sends its signals through invisible radio waves to----
access point
3.IEEE 802.11n equipped devices can be as far as 375 feet (114 meters) apart and can send and receive data at rates over standard. a. 75 b. 600 c. 100 d. 54
b. 600
-----is a wireless technology that can be used for data communications and transmit as far as 35 miles.
b.Microwave
The automatic connection between various Bluetooth devices creates a network called a(n) . a. micronet b.small net c. piconet d. Intranet
c. piconet
The maximum mandatory rate of an IEEE 802.11a WLAN, according to the standard, is------- a. 11 Mbps b. 24 Mbps c. 54 Mbps d. 108 Mbps
c.54 Mbps
One of the reasons that 802.11n achieves a higher throughput is that it bonds two ISM or U-NII channels. Another important reason is that it----- a.eliminates multipath interference b.uses antenna diversity c.can transmit using multiple spatial streams d.can transmit in any two frequency channels simultaneously
c.can transmit using multiple spatial streams
A(n)------ antenna transmits a signal in all directions with relatively equal intensity.
d. omnidirectional
ZigBee devices transmit data at rates of up to _________. a.2.5 Gbps b.625 Kbps c.250 Kbps d.250 Mbps
d.250 Mbps
Which of the following is not an example of a Bluetooth communication? a.Laptop connection to cellphone b.Smartwatch to mobile phone. c.Cellphones calls to headset. d.Hard drive to memory.
d.Hard drive to memory.
When signals are sent at frequencies that are closely grouped together, an errant signal may encroach on a close frequency, causing-----
time conflict
The distance between one positive peak and the next positive peak of a wave is called----
wavelength
Orthogonal Frequency Division Multiplexing (OFDM)
works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver.
