Chapter 6

Question 1

Frequency Range for ISM

Answer 1

902-928 Mhz

2. 4-2.4835 GHz
3. 725-5.85 Ghz

Question 2

Bandwidth of ISM?

Answer 2

234.5Mhz

Question 3

Common use for ISM?

Answer 3

Cordless Telephone
WLANs,
Wireless Public Branch Exchanges

Question 4

Frequency Range for Unlicensed Personal Communication Systems

Answer 4

1910-1930 MHz

2390-2400 MHz

Question 5

Bandwidth of UPCS?

Answer 5

30Mhz

Question 6

Common use for UPCS?

Answer 6

WLANs,

Wireless Public Branch Exchanges

Question 7

U-NII Frequency Range?

Answer 7

5. 15-5.25 GHz
6. 25 - 5.35 GHz
7. 725-5.825 GHz

Question 8

Bandwidth of U-NII

Answer 8

300 Mhz

Question 9

Frequency Range of Milimeter Wave

Answer 9

59-64 Ghz

Question 10

Bandwidth of Milimeter Wave

Answer 10

5 Ghz

Question 11

Uses for Milimeter Wave

Answer 11

Home Networking Applications

Question 12

What is ISM Band?

Answer 12

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

Question 13

900Mhz ISM band?

Answer 13

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

Question 14

2.4 Ghz ISM Band

Answer 14

2.4 - 2.5 GHz

Most common Wi-Fi band

Question 15

5.8 GHz ISM Band

Answer 15

5.725 - 5.875 GHz

150 MHz wide

Question 16

UNII Bands

Answer 16

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

Question 17

What does UNII stand for?

Answer 17

Unlicensed National Information Infrastructure

Question 18

UNII 1?

Answer 18

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

Question 19

UNII 2

Answer 19

5. 25 GHz to 5.35 GHz
   - 100 MHz
   - 4 Channels

IEE Maximum 200 mW IR
FCC Maximum 250 mW IR

Question 20

UNII 2 Extended

Answer 20

5. 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

Question 21

UNII 3

Answer 21

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

Question 22

60Ghz Frequency?

Answer 22

Potential speeds up to 7Gbps

Ultrahigh frequencies will have difficult penetrating walls

Question 23

WiGiG frequency?

Answer 23

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

Question 24

What is a Narrowband?

Answer 24

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

Question 25

What is Spread Spectrum?

Answer 25

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

Question 26

Main types of Spread Spectrum?

Answer 26

Frequency Hopping Spread Spectrum (FHSS) | Direct Sequence Spread Spectrum (DSSS)

Question 27

What does Multipath cause?

Answer 27

Inter-Symbol Interference | Fading in Signal

Question 28

Delay between the main and reflected signals is known as?

Answer 28

Delay Spread

Question 29

Multipath can be used as benefit for?

Answer 29

CDMA | MIMO

Question 30

What is FHSS?

Answer 30

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

Question 31

FHSS process?

Answer 31

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

Question 32

3 FHSS Definitions?

Answer 32

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

Question 33

What is DSSS?

Answer 33

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

Question 34

Difference between DSS and HR-DSSS?

Answer 34

DSSS provided 1 and 2Mbps | HR-DSSS added 5.5 and 11 Mbps

Question 35

Simple Spread Spectrum: Transmitter?

Answer 35

Narrowband data signal spread by wideband chipping sequence

Question 36

Simple Spread Spectrum: Receiver?

Answer 36

Wideband received signal despread with wideband chipping sequence

Question 37

What is Processing gain?

Answer 37

Processing gain is the factor of spreading in frequency and | The factor of decrease in power

Question 38

What is OFDM?

Answer 38

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

Question 39

2.4 Ghz channels?

Answer 39

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

Question 40

Which channels do not overlap?

Answer 40

1, 6, 11 | They need atleast 25Mhz separation between center frequencies

Question 41

Throughput vs Bandwidth?

Answer 41

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

Question 42

Throughput?

Answer 42

Depends on: - Frequency bandwidth - Data encoding - Modulation - Medium contention - Encryption - Number of current users - Many other factors