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Wireless Test 2 > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

Frequency Range for ISM

A

902-928 Mhz

  1. 4-2.4835 GHz
  2. 725-5.85 Ghz
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2
Q

Bandwidth of ISM?

A

234.5Mhz

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3
Q

Common use for ISM?

A

Cordless Telephone
WLANs,
Wireless Public Branch Exchanges

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4
Q

Frequency Range for Unlicensed Personal Communication Systems

A

1910-1930 MHz

2390-2400 MHz

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5
Q

Bandwidth of UPCS?

A

30Mhz

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6
Q

Common use for UPCS?

A

WLANs,

Wireless Public Branch Exchanges

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7
Q

U-NII Frequency Range?

A
  1. 15-5.25 GHz
  2. 25 - 5.35 GHz
  3. 725-5.825 GHz
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8
Q

Bandwidth of U-NII

A

300 Mhz

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9
Q

Frequency Range of Milimeter Wave

A

59-64 Ghz

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10
Q

Bandwidth of Milimeter Wave

A

5 Ghz

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11
Q

Uses for Milimeter Wave

A

Home Networking Applications

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12
Q

What is ISM Band?

A

Industrial, Scientific, Medical Band
Defined by ITU-T
License-Free Bands

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13
Q

900Mhz ISM band?

A

902-928 Mhz
Could interfere with GSM phones
Used by many consumer products, such as baby monitors and cordless home telephones

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14
Q

2.4 Ghz ISM Band

A

2.4 - 2.5 GHz

Most common Wi-Fi band

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15
Q

5.8 GHz ISM Band

A

5.725 - 5.875 GHz

150 MHz wide

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16
Q

UNII Bands

A

Contains 3 5Ghz Bands
Defined as Lower, Middle, and Upper UNII bands
Each band is 100MHz wide with 4 channels

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17
Q

What does UNII stand for?

A

Unlicensed National Information Infrastructure

18
Q

UNII 1?

A

Includes 5.15GHz to 5.25 GHz
IEEE defined max IR is 40mW
Typically used indoors

19
Q

UNII 2

A
  1. 25 GHz to 5.35 GHz
    - 100 MHz
    - 4 Channels

IEE Maximum 200 mW IR
FCC Maximum 250 mW IR

20
Q

UNII 2 Extended

A
  1. 47 GHz to 5.725 GHz
    - 255 Mhz wide
    - 11 Channels

IEE Maximum IR is 200 mW
Requires DFs and TPC
Indoor or Outdoor use

21
Q

UNII 3

A

5.725 GHz to 5.825 GHz
- 100 MHz
- 4 channels
IEEE Max Pow 800mW
Shares starting frequency with 5.8 Ghz ISM band

Typically outdoor point-to-point use

22
Q

60Ghz Frequency?

A

Potential speeds up to 7Gbps

Ultrahigh frequencies will have difficult penetrating walls

23
Q

WiGiG frequency?

A

WiGig certification to test interoperability of products that operate in the 60Ghz band

24
Q

What is a Narrowband?

A

Narrowband uses very little bandwidth
Intentional jamming or unintentional interference will likely cause disruption in the signal
Typically transmitted using higher power
Typically requires a license to limit the risk of interference between transmitters

25
Q

What is Spread Spectrum?

A

Uses more bandwidth than it is necessary
Less susceptible to intentional jamming or unintentional interference
Typically transmitted using lower power
Does not require a license

26
Q

Main types of Spread Spectrum?

A

Frequency Hopping Spread Spectrum (FHSS)

Direct Sequence Spread Spectrum (DSSS)

27
Q

What does Multipath cause?

A

Inter-Symbol Interference

Fading in Signal

28
Q

Delay between the main and reflected signals is known as?

A

Delay Spread

29
Q

Multipath can be used as benefit for?

A

CDMA

MIMO

30
Q

What is FHSS?

A

Frequency Hopping Spread Spectrum
Transmits bursts of narrowband signal over a wide band
Transmitted signal effectively occupies a wide band
Used by bluetooth

31
Q

FHSS process?

A

Transmits data on a narrow frequency
Hops to another narrow frequency and transmits more data
Continue process using a defined hopping sequence

32
Q

3 FHSS Definitions?

A

Hopping Sequence
- Predefined hopping pattern or a set
Dwell Time
- Period of time that the transmitter stays on a channel and transmits data
Hop Time
- The time it takes for the transmitter to change from one frequency to another

33
Q

What is DSSS?

A

Direct Sequence Spread Spectrum
Transmits signal across a frequency wide range
Uses chipping/spreading to convert data bits into a sequence
Defined in the original 802.11 standard

34
Q

Difference between DSS and HR-DSSS?

A

DSSS provided 1 and 2Mbps

HR-DSSS added 5.5 and 11 Mbps

35
Q

Simple Spread Spectrum: Transmitter?

A

Narrowband data signal spread by wideband chipping sequence

36
Q

Simple Spread Spectrum: Receiver?

A

Wideband received signal despread with wideband chipping sequence

37
Q

What is Processing gain?

A

Processing gain is the factor of spreading in frequency and

The factor of decrease in power

38
Q

What is OFDM?

A

Orthogonal Frequency Division Multiplexing
NOT a spread spectrum technology
Divides the whole bandwidth into subcarriers
- Transmits across 52 Subcarriers
- Each subcarrier is 312.5 KHZ wide
- 48 Subcarriers are used to transmit data
- Remaining 4 are known as pilot carriers

39
Q

2.4 Ghz channels?

A

Divided into 14 channels by 802.11 - 2007 standard
Each channel is 22 Mhz
Distance between neighbor channels is 5MHz
Channels will not overlap if they are separated by 5 or more channels

40
Q

Which channels do not overlap?

A

1, 6, 11

They need atleast 25Mhz separation between center frequencies

41
Q

Throughput vs Bandwidth?

A

Data rates are also known as data bandwidth
Due to half-duplex nature of 802.11, actual throughput it typically 50% or less of the data rate.
54Mbps link will have about 20Mbps aggregate throughput.
Throughput is always lesser than bandwidth

42
Q

Throughput?

A

Depends on:

  • Frequency bandwidth
  • Data encoding
  • Modulation
  • Medium contention
  • Encryption
  • Number of current users
  • Many other factors

Wireless Test 2 (5 decks)

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