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Wireless Fundamentals > Chapter 1. > Flashcards

Chapter 1. Flashcards

1
Q

What year did 802.11b come out and how fast was it able to move data?

A

1999 and 5.5Mbps / 11 Mbps.

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2
Q

Which of the following wireless communication parameters and usage are typically governed by a local reg authority?

A

Frequency, bandwidth, max transmit power, max EIRP, indoor/outdoor usage.

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3
Q

What is WMM and what amendment created it? What is it used for? What is need for it to be supported? Which wireless PHY is it mandatory for? Optional for?

A

WiFi Multimedia (WMM), is based on QoS mechanisms that were originally defined in IEEE 802.11e amendment.

Enabled wireless networks to give priority to traffic generated by different applications.

WMM is supported by both the access point and the client device, traffic generated by time sensitive applications such as voice and video can be prioritized for transmission on the half duplex RF medium.

Mandatory for 802.11n. Optional for all others below N.

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4
Q

What is Current State Keying?

A

With current state techniques, the current value (the current state) of the
signal is used to distinguish between 0s and 1s.

If the state stays the same, it could be a 1.
If the state changes, then it could be a 0.

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5
Q

What is wavelength and how is it usually measured?

A

The distance between similar points on two back to back waves.

Measured usually between the tips of peaks.

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6
Q

What is State Transition Keying technique?

A

This means that if the current state of a signal is detected to be moving, then it could be a 1.

If the current state has not changed, it could be a 0.

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7
Q

WMM-Admission Control (Explain in detail)

A

Allows wifi networks to manage network traffic based upon
1. Channel conditions
2. Network traffic load
3, Type of traffic (Voice, video, best effort data, or background data)

The access point allows only the traffic that it can support to connect to the network, based on available network resources. This allows users to confidently know that, when the connection is established, the resources will be there to maintain it.

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8
Q

What is the max data rate of g?

A

54 Mbps

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9
Q

What is frequency shift keying? What state is it? How is the data interpreted? Why is the not practical today?

A

Varies the frequency of the signal to represent the binary data.

This is a CURRENT state technique. Where one frequency can represent a 0 bit and another frequency can represent a 1 bit. The shifting of data can determine the data being transmitted.

The faster frequency wave is interpreted as a binary 1, and the slower frequency wave is interpreted as a binary 0.

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10
Q

What year was the original 802.11 amendment ratified and by whom?

A

In 1997, the IEEE ratified the original 802.11 standard

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11
Q

What is the International Organization for Standardization?

A

This is an organization that identifies business, government, and society needs and develops standards in partnership with the sectors that will put them to use.

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12
Q

Which sublayer of the OSI model’s data link layer is used for communication between 802.11 radios?

A

The MAC layer.

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13
Q

What is WMM Power Save? Why is it important?

A

Helps conserve battery power for devices using WiFi radios by managing the time the client spends in sleep mode.

Devices like VoIP, handhelds scanners. Both device and access point must support WMM power save.

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14
Q

What properties can be modified to encode signals?

A

State, frequency, amplitude, phase

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15
Q

What is multiple phase-shift keying?

A

When more than two phases are used.

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16
Q

What does the WiFi Alliance due?

A

Tests wireless devices against 802.11 standards to ensure interoperability.

17
Q

What is a symbol period? What does the receiving station do with this?

A

When a signal being received is divided into periods of time.

The receiving station then samples or examines the wave during this symbol period to determine the amplitude of the wave. Depending on the value of the wave’s amplitude, the receiving station can determine the binary value.

18
Q

What is signal modulation ?

A

When a carrier signal is modified; which a receiving radio can interpret as either a 0 or a 1. The result is data transmission.

19
Q

What does the Institute of Electrical and Electronics Engineers (IEEE) do?

A

Creates standards for compatibility and coexistence between networking equipment.

20
Q

What is phase? Divided into what? What does it mean to be out of phase?

A

A relative term. It is a relationship between two waves with the same frequency.

Divided into degrees.

Out of phase means they are not together.

21
Q

What are Robust Security Network capabilities? What are the requirements? What amendment did this come from?

A

Robust Security Network capabilities are security mechanisms that were originally defined in the IEEE 802.11i amendment. Devices must support Wi-Fi protected access (WPA) and WPA2 security mechanisms for personal and enterprise environments. Must also support Extensible Authentication Protocol (EAP), which is used to validate the identity of the wireless device or user.

22
Q

What is the max data rate of 802.11a?

A

54 Mbps

23
Q

What does the IETF (Internet Engineering Task Force) do?

A

Responsible for creating Internet standards. Many of these standards are integrated into the wireless networking and security protocols and standards.

24
Q

What is the max data rate of b?

A

11 Mbps

25
Q

Which layer of the OSI is 802.11 wireless networking often implemented?

A

At the access layer.

26
Q

What is Voice Enterprise? What must it do at all times? What are the many criteria that need to be met for this to work?

A

Voice enterprise offers enhanced support for voice applications in enterprise wifi networks.

Enterprise grade equipment must provide consistently good voice quality under all network load conditions and coexist with data traffic.

  1. Voice traffic must be placed in the highest-priority queue. (Access category voice, AC_VO)
  2. Voice Enterprise equipment must also support seamless roaming
  3. WPA2-Enterprise Security.
  4. Optimization of power through the WMM-Power Save mechanism.
  5. Traffic management through WMM admission control.
27
Q

What is the max data rate of ac?

A

1.3 Gbps

28
Q

What is a keying method?

A

The method of manipulating a signal so that it can can represent multiple pieces of data.

29
Q

What is the Extensible Authentication Protocol (EAP)?

A

Used to validate the identity of the wireless device or user.

30
Q

What is phase-shift keying? What state does it use? Is this used today? What does the more advanced versions do?

A

PSK varies the phase of the signal to represent the binary data.

This is a state transition tecnique where the change of the phase can represent a 0 bit and the lack of a phase change can represent a 1 bit.

The more advanced versions can understand more than 1 phase shift, and usually many during a cycle. Each of the four phases is capable of representation two binary vales like 00 or 01….instead of 0 or 1, shortening transmission time.

31
Q

What is the max data rate of n?

A

450 Mbps

32
Q

Which organization is responsible for RFC’s ?

A

The IETF (International Engineering Task Force)

33
Q

What year and where was the first wireless network created and what was it called?

A

1970, University of Hawaii, called ALOHAnet.

Wireless Fundamentals (19 decks)

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