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108 > 802.11 Standards > Flashcards

802.11 Standards Flashcards

1
Q

At what layer does 802.11 technology specifies?

A

Physical and Mac Sublayer of Data like layer

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2
Q

What was obsolete in 802.11 standard?

A

Infrared Medium

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3
Q

_______ Signal can be defined as narrow band or spread spectrum ?

A

Frequency hoping spread Spectrum (FHSS)

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4
Q

What is a spread spectrum ?

A

When band width is wider than data what is required to carry data

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5
Q

Which spectrum technology used Fixed channel ?

A

Direct sequence spread spectrum

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6
Q

Which amendment was created as single document including 8 amendment? In which year ?

A

802.11-2007 Amendment

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7
Q

What frequency is used in 802.11a

A

5Ghz

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8
Q

What is the RF technology used ?

A

Orthogonal frequency Division Multiplexing (OFDM)

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9
Q

Initially 5Ghz radio transmitted in ?

A

Three different 100MHz channel

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10
Q

What are these three band called ?

A

Unlicensed National Information Infrastructures (U-NII) frequency band

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11
Q

How many bands are available now ?

A

12

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12
Q

What technology does 802.11b use ?

A

High rate Direct Sequence Spread Spectrum (HR-DSSS)

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13
Q

What is the frequency space of 802.11b ?

A

2.4GHz -2.4835 GHz ISM Band

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14
Q

What does ISM mean ?

A

Industrial , Scientific, Medical

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15
Q

What technology does 802.11g use ?

A

Extended Rate Physical (ERP)
ERP- OFDM
ERP-DSSS/CCK (Complementary Code keying)

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16
Q

What frequency band did 802.11g use ?

A

2.4GHz-2.4835 GHz ISM Band

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17
Q

What data rates are possible in 802.11g ?

A

6,9,12,18,24,36,48,54

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18
Q

Why data rates of 6,12,24 are only used ?

A

For backward capabilities

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19
Q

Data rates in 802.11b ?

A

DSSS - 1, 2 Mbps

HR-DSSS - 5.5,11 Mbps

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20
Q

Data rates in 802.11g?

A

ERP DSSS/ CCK - 1,2,5.5 and 11
ERP OFDM- 6,12,24
Also supported 9,18,36,48,54

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21
Q

What are the mandatory data rates in 802.11a ?

A

6,12 and 24

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22
Q

Which year did legacy 802.11 ratified ?

A

1997

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23
Q

Which year did 802.11b ratified ?

A

1999, HR (2003)

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24
Q

Which year did 802.11g ratified ?

A

2003

25
Q

Which year did 802.11a ratified ?

A

1999

26
Q

Key component of Wireless Security ?

A

Data privacy
Data integrity
Authentication

27
Q

What was the encryption system used in 802.11 ?

A

64-bit static encryption called Wired Equivalent Privacy (WEP)

28
Q

What was the new securty amendment?

A

802.11i

29
Q

What does it defined ?

A

A Robust Security Network (RSN)

30
Q

What encryption was used for data privacy and confidentiality in 802.11i ?

A

Counter mode with Cipher Block Chaining messege authentication Code protocol (CCMP)

31
Q

What algorithm does CCMP use ?

A

Advanced Encryption Standard (AES) Algorithm

32
Q

What methods were used for authentication in IEEE 802.1x?

A

Authorisation framework or pre-shared keys (PSK)

33
Q

What did 802.11x solution required ?

A

An Extensible Authentication Protocol (EAP)

34
Q

Did 802.11i specified any EAP method?

A

No

35
Q

What does Robust Security Network defines ?

A

Entire method of establishing Authentication, negotiating security association and dynamically generating encryption keys for client and access points

36
Q

What technology was used in 802.11r ?

A

Fast secure roaming

37
Q

What was 802.11w frames refered as ?

A

Robust Management Frame

38
Q

How robust management frame protected ?

A

By Robust management frame protection service

39
Q

What technology used is 802.11n ?

A

MIMO- OFDM

40
Q

What is 802.11n know as ?

A

High throughput (HT)

41
Q

What rates does 802.11n support ?

A

600Mbps

42
Q

Benefits of MIMO technology?

A

Increased throughput and greater range

43
Q

802.11n exists in which layer using MIMO?

A

Physical

44
Q

MIMO used multiple radios and Antenna known as ?

A

Radio chain

45
Q

Which method is used Transmitting Multiple stream of data in MIMO?

A

Spatial Multiplexing (SM)

46
Q

Use of multiple receiver in MIMO increases ?

A

SNR

47
Q

What diversity technique is used to transmit and receive data?

A

Space time block coding (STBC)

Cyclic shift diversity (CSD)

48
Q

Can MIMO send individual unique data stream ?

A

Yea

49
Q

What are indipendent data stream known as ?

A

Spatial Stream

50
Q

What is MIMO diversity?

A

Method of using multiple antenna to survive the negative effect of multipath

51
Q

What is MIMO diversity?

A

Method of using multiple antenna to survive the negative effect of multipath

52
Q

What is STBC ?

A

Space Time block Coding , A method where same information is transmitted on two or more Antenna.

53
Q

When is STBC used ?

A

When the number of radio chains exceed the number of spatial stream

54
Q

Where is CSD used ?

A

In 802.11g and 802.11a devices

For mixed mode deployment- 802.11n coexist with 802.11g and 802.11a

55
Q

What does transmit Beamforming relies on ?

A

Implicit feedback and Explicit feedback

56
Q

What does transmit Beamforming relies on ?

A

Implicit feedback and Explicit feedback

57
Q

What can be used as Sounding frame ?

A

Any frame

58
Q

What can be used as Sounding frame ?

A

Any frame

108 (7 decks)

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