Wireless Communications

Which of the following represent a particular stage of development associated with mobile multimedia devices?

-Cameras installed in phones -Music playing capabilities -Video functions and applications

Which of the following is a multiple access technique where everyone uses the same frequency simultaneously and each conversation is encoded and spread over the full spectrum of the channel?

-Code division multiple access (CDMA) -Spread spectrum

Which of the following determines the transmission speed of a WLAN?

-Collision detection -Distance from the wireless access point (WAP) -Frequency band(s) used

Which of the following may affect the performance of wireless communications?

-Environmental obstacles -Range and electrical power -Weather

Which of the following is/are driving the economic value of Wi-Fi?

-Free Wi-Fi in public spaces -Internet service providers -Residential use

Which of the following was the primary purpose of switching to digital, 2G cellular?

-Increased capacity and roaming capability -Increased security -Improved spectrum utilization

Which of the following are IP multimedia subsystem (IMS) applications?

-Instant Messaging -Push-To-Talk -Video Telephony

Which four major techniques are used to allocate the available radio spectrum?

-Space Division Multiplexing -Frequency Division Multiple Access (or FDMA) -Time Division Multiple Access (or TDMA) -Spread Spectrum (implemented as Code Division Multiple Access [or CDMA] in 2G networks and as either W-CDMA or OFDM in 3G cellular networks)

In the past, the use of wireless connectivity was an extra that needed to be justified. Which of the following reasons justified the use of wireless?

-When the time to deploy was an issue -When wire could not be economically justified -When wire could not be physically installed

Cognitive radio starts with SDR's ability to adapt to changing communications protocols and frequency bands and adds _____.

-a smart system in which a radio device and its antenna can adapt their spectrum use in response to their operating environment -the ability to perceive the world around it and learn from experience -the ability to work in any mode, like Wi-Fi or VoIP or cellular, depending on what makes sense given location and/or time

The purpose of IP multimedia subsystem (IMS) is to _____.

-address the critical signaling and session control issues associated with multimedia services -ease the convergence between wireless and wireline networks

Orthogonal frequency division multiplexing (OFDM) offers _____ compared to the older spread spectrum techniques.

-improved bandwidth -improved resistance -varied up-and downstream channel speeds

First generation WLAN products were quite limited, operating at only one megabit per second to 11 megabits per second. The current generation operates up to _____.

10 Gbps

Wi-Fi 4 operates in both the 2.4 Gigahertz and 5 Gigahertz frequency bands with a theoretical speed of 54 megabits per second. The most current standard is 802.11ax, also known as Wi-Fi 6 and 6E. It operates on the 2.4/5/6 Gigahertz bands and has a theoretical speed of _____ with a throughput of about _____.

10 Gbps /2 Gbps

In general, a generation is defined by the technology changes over a _____ period.

10-year

When comparing 4G and 5G, the peak data rates for 4G are about 1Gb/s while 5Gs peak data rates are about _____.

20 Gb/s

The number of 5G subscriptions is expected to grow to 3.5 billion globally, about 40% of all mobile subscriptions at that time, by the end of _____.

2026

There are _____ power classifications for Bluetooth technology. _____ is the most common allowing transmission up to about 30 feet.

3 / Class 2

UWB operates at a very low power level, 0.2 milliwatt. This restricts its range to distances of 300 feet (100 m) or, more typically, as little as _____.

30'

_____ was the first step toward broadband wireless, but has mainly been replaced by 4G.

3G

NFC is a very short-range technology with a typical range of _____.

4" to 8"

As of early 2021, _____ is the dominant wireless cellular technology representing over 62% of mobile subscribers.

4G

By supporting mobility and by being faster and cheaper to deploy, it is expected that _____ will disrupt wired broadband access alternatives, including DSL and cable modems.

4G

In 2021, how many 5G smart phones were expected to be sold?

539 million

_____ was launched in late 2018. It is projected to grow to 3.5 billion subscribers by 2026, representing 40% of mobile subscribers worldwide.

5G

Which of the following does not utilize orthogonal frequency division multiplexing (OFDM)?

802.11b

1G was based on what technology?

Analong

Which of the following have often been the most neglected component in a wireless system, yet they are the most critical part of radio systems?

Antennas

_____ is an industry specification for short-range radio frequency-based connectivity for portable personal devices.

Bluetooth

_____ refers to the ability to send information in both directions over a single channel.

Duplex transmission

4G networks support both traditional circuit-switched and packet-switched infrastructures.

False

Antennas are active devices that create energy.

False

Software-defined radio enabled devices and equipment cannot be dynamically programmed in software to reconfigure the characteristics of equipment.

False

What is the number one, top application type for mobile devices?

Games

Which of the following does the "G" in 2G, 3G, 4G, 5G, and 6G stand for?

Generation

Who is credited with the invention of the radio transmitter?

Guglielmo Marconi

_____ radio frequencies offer greater bandwidth, but are greatly affected by interference limiting their transmission distance.

Higher

The key to push-to-talk over cellular service is _____.

IMS

Which of the following is not true about ZigBee?

It supports multimedia entertainment devices.

Of the four main RFID frequencies, the reading range of _____ tags are only up to about three feet (one meter).

LF and HF

Intelligent antennas can be used to mitigate the effects of multipath and other environmental interactions. Which of the following smart antennas can be used to increase bandwidth?

Magnetic polarization antenna

_____ networking is an innovative approach to building wireless broadband data networks. This creates a resilient network in which connections are continuous and able to reconfigure around blocked paths. It turns wireless access points into router nodes with peer radio devices.

Mesh

_____ supports standard image formats such as GIF and JPEG, video formats such as MPEG-4, and audio formats such as MP3 and WAV for messaging.

Multimedia messaging system (MMS)

Which smart antenna type has at least two transmit antennas and at least two receive antennas, but likely has more receive antennas than transmit antennas?

Multiple-input multiple-output (MIMO) antenna

_____ is a short-range, contactless communications protocol, that enables easy-to-use, secure connectivity between devices.

Near field communications (NFC)

_____ allows multiple users to transmit simultaneously on different subcarriers resulting in improved spectral efficiency, is immune to interference, and is, therefore, capable of high data throughput.

OFDMA

There are two main types of antennas, omnidirectional and directed. _____ antennas are used for communicating with mobile stations spread out in all directions.

Omnidirectional

_____ is defined as the transmission and reception of electrical impulses or signals through electromagnetic waves without the use of wires.

Radio

_____ provides a mechanism for transmitting short messages to and from wireless devices, acting as a store-and-forward system for short messages up to 160 alphanumeric characters in length.

Short message service (SMS)

Which of the following are the primary areas the regulatory aspect of radio communications covers?

Spectrum management and political issues

3G networks have given way to 4G, with many carriers planning to decommission their 3G networks in 2022.

True

4G is intended to accommodate the high data rates, low latencies, and quality of service required by applications like streaming video, mobile gaming, and HDTV.

True

Antennas may be designed to partially reject interference and unwanted signals and/or focus energy in a particular direction when transmitting.

True

Bluetooth wireless technology is the leading short-range wireless technology on the market today. It continues to develop, building on its inherent strengths—small-form-factor radio, low power, low cost, built-in security, robustness, ease-of-use, and ad hoc networking abilities.

True

Despite the maximum speeds quoted in wireless specifications, the actual data throughput is generally quite a bit lower. This is because 802.11 uses a collision avoidance access technique rather than the collision detection method used in wired Ethernet LANs. The method waits for an acknowledgment from the other end to determine whether the packet was transmitted properly, thus reducing the throughput.

True

Looking ahead to 6G, one can expect extremely high reliability, extremely high data rates and capacity, extremely low latencies, and Gb/s coverage everywhere including, sky, sea, and space.

True

Mobile IP allows a user with a mobile device whose IP address is associated with one network to stay connected when moving to a network that has a different IP address. This allows a user to keep the same IP address, stay connected, and maintain ongoing applications while roaming between IP networks.

True

One of the reasons UWB is called "ultra-wideband " is that it spreads its signal over a very wide band of frequencies.

True

The NFC-enabled phone can replace a wallet full of cards. It can be used as a loyalty card, credit card, or train or bus ticket.

True

Today 's smartphones all feature the ability to switch between Wi-Fi and mobile data automatically to maintain a stable network connection.

True

Today, mobile presence service is an essential component of social network applications because it maintains each mobile user's presence information, such as the current status (online/offline), GPS location, and network address.

True

UWB refers to a technique based on transmitting very-short-duration pulses, where the occupied bandwidth is very large, allowing for very high data rates.

True

Wireless local area networks (WLANs) were originally meant to be an augmentation, not a replacement, of wired LANs and premises telephone systems.

True

ZigBee supports three network topologies: star, mesh, and cluster tree.

True

_____ is the current state-of-the-art in standards-based WLAN security.

Wi-Fi protected access 3 (WPA3)

Since the beginning of radio communications, there have been two main goals of the industry; they are _____.

expanding capacity and maintaining quality

A WPAN is characterized by limited distance, limited throughput, and _____.

low volume

In the realm of the public domain today, the primary application for WLANs is simply _____.

mobility

The larger the cell size in the cellular architecture, the _____.

more power required

A _____ system uses its multiple antennas to simultaneously transmit data to the receivers in small pieces, and the receivers then process the data flows and put them back together.

multiple-input multiple-output (MIMO) antenna

Key concerns about voice over WLAN include _____ and _____.

quality of service / capacity

Push-to-talk is best suited for _____.

quick communication among end users

Narrowband, also called baseband, implies _____channel(s). Wideband, also referred to as broadband, implies the use of _____ channel(s).

single / multiple

RFID is a method of remotely _____ and _____ data using devices called RFID tags.

storing / retrieving

Which of the following is not an application of an early WLAN?

support for QoS

Applications and support for 3G do not include _____.

support for virtual reality

Frequency is used to classify radio waves, describing _____.

the number of times a signal cycles per second

An RFID reader _____ energy to RFID tags by emitting electromagnetic waves through the air. RFID tag antennas collect the RF energy from the reader antenna and use it to power up the microchip. Tags listen for a radio signal sent by an RFID reader. When an RFID tag receives a query, it responds by transmitting its unique ID code and other data back to the reader.

transfers

A network serving a single person or small workgroup is called a _____.

wireless personal area network (WPAN)