-
Frequency Hopping Spread Spectrum (FHSS)
- transmitting radio signals by rapidly switching a carrier among frequency channels using a pseudorandom
- sequence known to both the transmitter and the receiver
data rate of 1 and 2 Mbps
-
Direct Sequence Spread Spectrum (DSSS)
- Data signal at the sending station is combined with a higher data rate bit sequence, or chipping code, that divides the user data according to a spreading ratio.
- data rate of 1 and 2 Mbps
-
Orthogonal Frequency Division Multiplexing (OFDM)
transmits multiple signals simultaneously over a single transmission path, such a cable or wireless system
- signal travels within its own unique frequency range (carrier), which is modulated by the data (text,
- voice, video, etc)
data rate of 6, 9, 12, 18, 24, 36, and 54 Mbps
-
HR DSSS
the 802.11b 5.5 and 11 mbps speeds
-
ERP extended rate physical
- physical layer specification defined for clause 19 radios.
- operates at 2.4 ghz ism band
-
ERP OFDM
data rates of 6 - 54Mbps
-
PHY (DSSS and FHSS require and support data
rates of
1 and 2 Mbps.
-
OFDM and ERP-OFDM support data rates of
1- of 6, 9, 12, 18, 24, 36, 48, and 54 Mbps, but only 6, 12, and 24 Mbps are mandatory)
-
data rates
number of bits/ second the physical layer carries during a single frame transmission
-
throughput
measurement of the amout of user data that successfully transverses the network over a period of time
-
PHY frequency band
. DSSS, FHSS, HR-DSSS, and ERP
-
ODFM frequency bands
5 GHz UNII bands
-
DSSS, FHSS, HR-DSSS, and ERP frequency bands
2.4 ghz ISM band
-
three operational modes of ERP
- b only
- g only
- b/g mixed
- support different spread spectrum technologies and have different aggregae throughput reults
-
Transmit Power Control TPC
802.11h admendment, regulate power levels in .11a erc and fcc mandate radio at 5Ghz,
-
802.11i security
RSN (Robust Security Network). 802.11i makes use of the Advanced Encryption Standard (AES) block cipher, whereas WEP and WPA
-
802.11e
- Defines Quality of Service (QoS) mode of operation
- Defines enhanced medium access methods
- Uses Hybrid Coordination Function (HCF
-
802.11s
- Adaptive configuration support
- Standardization of Mesh Networking
- Uses the MAC and PHY layers of 802.11
- Specifies the DS be Wired
-
-
Uses High Throughput Orthogonal Division
- Multiplexing (HT-OFDM)
- Uses MIMO
- Uses Channel Bonding
- Works in both 2.4 GHz and 5 GHz bands
-
802.11.p
- 802.11 that support Intelligent
- Transportation Systems (ITS)
- Also known as Wireless Access in Vehicular
- Environments (WAVE)
- Can reach speeds up to 124 MPH/200KPH at 3281
- feet/1000 Meters
- Will possibly be licensed in the 5.9 GHz band
- but supports 5 GHz bands
-
802.11w
- Uses Protected Management Frames
- Forces mutual authentication prior to deauthentication and disassociation
- Reduces simple denial of service attacks
-
Industrial, Scientific, and Medical bands (ISM)
-
Narrowband
signals transmitted using higher power, and very little bandwidth
-
Spread Spectrum
- uses more bandwidth for transmission and less
- power
-
how coding and modulation of OFDM
OFDM uses Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) modulation for lower data rates
•QAM (Quadrarture Amplitude Modulation) is a hybrid of phase and amplitude modulation
-
dwell time
amout of time that the FHSS system transmits on a specific frequency befor it switches to the next frequency in the hop set
-
hop time
the amount of time it takes for the transmitter to change from one frequency to another
-
delay spread
dely between the reception of the main signal and the reflected signal
-
ISM Industrial, Scientific,
and Medical bands (ISM)
- Not being used by 802.11 devices
- Legacy wireless networking
-
Differential Binary Phase
Shift Keying (DBPSK) modulation cna coding
- 1 Mbps
- modulation for lower data rates
-
Differential Quadrature
Phase Shift Keying (DQPSK) modulation and coding
- at 2, 5.5 and 11 Mbps
- modulation for lower data rates
-
Complementary Code Keying
- 4 bits of data with 8 chips (5.5 Mbps) and
- can encode 8 bits of data with 8 chips (11 Mbps)
-
Barker Codes
- Let the code to be transmitted is 10
- •11111111111 00000000000 XOR
- 10110111000 10110111000
- 01001000111 10110111000
-
QAM (Quadrarture
Amplitude Modulation)
is a hybrid of phase and amplitude modulation
16-QAM and 64-QAM is used for higher data rates
-
900 MHz ISM Band
26 MHz wide
•Includes 902 MHz to 928 MHz
•Legacy wireless networking
- •Partially allocated for Global System Mobile
- Communications (GSM Cellular) in parts of the world
•Used by cell phones
•Not being used by 802.11 devices
-
2.4 GHz ISM Band
- 83.5 MHz Wide
- Covers 2.4 GHz to 2.4835 GHz
- USA has 11 channels, each of 22MHz wide
- Channels 1,6 and 11 are most widely used because they don’t overlap
- Used by 802.11, 802.11b, g and n IEEE standards
- 2.4 GHz ranges uses DSSS modulation
- Also widely used by non-networking devices (microwaves, baby monitors, etc.)
- Devices transmitting on Adjacent Overlapping Channels cause Interference for each other.
- Channels 1, 6 and 11 are
- Adjacent Non-Overlapping Channels.
- That is why they are used so often in
- co-location of 802.11 devices
-
5.8 GHz ISM Band
- 150 MHz Wide
- Includes 5.725 GHz to 5.875 GHz
- Divided into channels, each 20 MHz wide
- Total of 23 non-overlapping channels
- Used by many non-networking devices
- Should not be confused with UNII-3 Bands
- 5.81 ISM band is 50 MHz larger than UNII-3
- Used by 802.11a standard and the new 802.11n draft Uses OFDM
- Data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbps are defined
-
Unlicensed National
Information Infrastructure (UNII) Bands
Contains Three 5 GHz Bands
- Defined as Lower, Middle, and Upper UNII
- Bands (aka UNII 1, UNII 2, and UNII 3)
- In the United States, The FCC opened more
- channels for UNII 2. Now UNII 2 Extended
- offers 11 more channels for use, with some restrictions.
-
UNII 1
(The Lower UNII Band)
- Has 4 Channels
- Includes 5.15 GHz to 5.25 GHz
- Typically Used Indoors
- Allowed a Maximum IR of 50 mW by
- the FCC
- Most Vendors Limit the IR to 40 mW
- Prior to 2004 UNII 1 Devices Were Required to
- use Fixed Antennae
- After 2004, Detachable Antennae may be used
- Within Regulatory Body Guidelines
-
UNII 2
(The Middle UNII Band
- Has 4 Channels
- Includes 5.25 GHz to 5.35 GHz
- IEEE Maximum 200 mW IR
- FCC Maximum 250 mW IR
- Power limits may vary by country
-
UNII 2 Extended
- Has 11 Channels
- FCC added 255 MHz of Spectrum to within 5.47
- GHz to 5.725 GHz
- Maximum Allowed IR Strength 250 mW
- IEEE Maximum IR Strength 200 mW
- Requires Dynamic Frequency Selection (DFS)
- Requires Transmit Power Control (TPC)
-
UNII 3
(The Upper UNII Band)
- Has 4 Channels
- Includes 5.725 GHz to 5.825 GHz
- FCC maximum power 1000 mW
- IEEE maximum power 800 mW
- Shares starting frequency with the 5.8 GHz
- ISM Band
- UNII 3 is 100 MHz wide while the 5.8 GHz ISM
- Band is 150 mW wide
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