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CWNA

Michael Gleeson CWNA - Englisch 152 Karten

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  1. 1What do these stand for, ITU-R, FCC, IEEE, IETF?International Telecommunication Union Radio-communication
    Federal Communications Commission
    Institute of Electrical Electronic Engineers
    Internet Engineering Task Force
  2. 2What is RSN, CWG-RF?Robust Secuirty Network
    Converged Wireless Group-RF
  3. 3What does IR and EIRP stand for?Intentional Radiator
    Equivalent Isotropically Radiated Power
  4. 4What are RFC's and who do they belong to?RFCs are Request for Comments by the IETF
  5. 5What is TDLS?Tunneled Direct Link Setup
  6. 6What does SQ, CCK, BER, CCA, DRS mean?SQ: Signal Quality
    CCK: Complimentary Code Key
    BER: Bit Error Rate
    CCA: Clear Channel Assessment
    DRS: Dynamic Rate Switching
  7. 7What is Fade Margin?It is the buffer size/grace size. You typically allow 25 dBi as a safety net on long distance Point to Point Links due to FSPL and attenuation
  8. 8What is SOM?System Operating Margin: Difference between Received Signal and the necessary Signal required for reliable communication
  9. 9What is an example of a Point Source?Isotropic Radiator
  10. 10How much dBi gain do you need to add to double the distance?6 dBi
  11. 11What are is the rule of 10s & 3s?to add 3dB gain, double
    to add 3dB loss, halve
    to add 10dB multiple by 10
    to add 10dB loss divide by 10
  12. 12What are the absolute and relative measures of power?Absolute: watt (W), milliwatt (mW), dBm
    Relative: dBi, dB, dBd
  13. 13What are the four results of Multipath?Downfade
    Upfade
    Nulling
    Data Corruption
  14. 14What are: Downfade Upfade Nulling Data CorruptionDownfade - decreased signal strength, arrive at same time out of phase with primary wave
    Upfade: increased signal strength, arrive at same time in phase with primary wave
    Nulling. Cancellation. Arrive 180 degrees out at the same time.
    Data Corruption: delay spread time causes bits to overlap causing corruption
  15. 15What is ASK in relation to modulation?Amplitude Shift Keying: Varies the amplitude or height. Current state technique. ASK can be affected by Noise, as alters signal to something incorrect
  16. 16What is FSK in relation to modulation?Frequency Shift Keying: Varies the frequency. Is current state technique. Used in more legacy deployments.
  17. 17What is PSK in relation to modulation?Phase Key Shift Keying: varies the phase. State transition technique. More currently used one in 802.11-2012
  18. 18What is Voice Personal?Offers enhanced support for Voice applications in residential & small business WiFi. One AP, mixed Voice & Data Traffic
  19. 19What is Voice Enterprise?Enterprise grade voice equipment, must provide consistently good voice quality. AP and devices must support WMM (voice traffic prioritised. Supports seamless roaming, WPA2 security, WMM-PS and traffic control through WMM-AC
  20. 20What does adding 2.14 to something relate to?If the antenna is measured in dBd, then you add 2.14 to it to get the dBi value
  21. 21How do you calculate Beamwidth on a chart? Draw it and explainGo to the strongest part of the signal (no.1 arrows). Then move down the pattern (no.2 arrows) until you reach the point where you're 3dB closer to the center of the diagram (no.3 arrows).
  22. 22What is the definition of Beamwidth?Is the measurement of how broad or narrow the focus of an antenna is-and is measured both horizontally & vertically.
  23. 23What is Static Beamforming?Is performed by using directional antennas to provide a fixed radiation pattern. Uses multiple directional antennas, all clustered together but aimed away from a center point or location.
  24. 24What is Dynamic Beamforming?Focuses the RF energy in specific direction and shape. The pattern can change on a frame-by-frame basis. Ruckus are the only provider that can do this at the moment.
  25. 25What is Transmit Beamforming?Transmits multiple phase-shifted signals with the hope and intention that they will arrive in phase at the location where the transmitter believes that the receiver is located.
  26. 26What determines the size of the Fresnel Zone?Distance and Frequency
  27. 27What does VSWR stand for and mean?Voltage Standing Wave Ratio (Ratio of Impedance Mismatch)
    Numerical relationship between the measurement of the minimum voltage along the line (generated by Transmitter) and the minimum voltage along the line (received by the Antenna)
  28. 28What are the 4 types of Antenna?Omnidirectional
    Semidirectional
    Highly Directional
    Sector
  29. 29What the characteristics of a Omnidirectional Antenna? Give example of Antenna typeRadiate RF in a fashion similar to the way a table or floor lamp radiates light. Designed to cover all directions (360 degrees) - Donut shaped
    Indoor AP - Veritcal & Dipole
  30. 30What light analogy can be used for a Semidirectional Antenna? Give example of Antenna typeRadiates RF in a similar fashion to way a wall light does
    Patch/Panel/Yagi Antenna
  31. 31What light analogy can be used for a Highly Directional Antenna? Give example of Antenna typeRadiates RF in a similar fashion to a spotlight. Concentrated for long distance
    Parabolic Dish
    Grid Dish (Satellite TV)
  32. 32explain how 3 dBm gain & loss affects absolute power?gain doubles the absolute power (mW)
    loss halves the absolute power (mW)
  33. 33explain how 10 dBm gain & loss affects absolute power?gain multiples by 10 the absolute power (mW)
    loss divides the absolute power (mW)
  34. 34What does dB, dBi, dBd, dBm actually stand for, i.e i d m etc?dB - Decibel
    dBi - Decibel Isotropic
    dBd - Decibel Dipole
    dBm - Decibel relative to Milliwatt
  35. 35what dB value double and halves the distance no matter what?+6dB
    -6dB
  36. 36after how many miles does the earths curvature start to impeded RF?7 Miles
  37. 37how long is a wavelength in inches?5" roughly
  38. 38How much dB should you allow for for fade margin or buffer as it's also called?10-25 dB
  39. 39What does RSL stand for?Received Signal Level
  40. 40What are do the two Fresnel zones represent? Zone 1 & 2Zone 1 means signal is in-phase
    Zone 2 means the signal is out-of-phase
  41. 41What do you call two sector antennas back to back?Sectorised Array
  42. 42What does VSWR do? what affects can it have?Can cause a decrease in power due to a mismatches in impedance.
    Can cause Transmitters to overheat and break due to high return Voltages
  43. 43What is the standard ohms for impedence in Wireless devices?50 ohms
  44. 44what does ohm measure?Electrical Resistance
  45. 45How much buffer should you allow for a fade margin in dB?10-15 dB
  46. 46What do the following mean? SOMSOM - System Operating System
  47. 47When was UNII 2 Extended added?802.11
  48. 48Tell me the ratificationyears for 802.11, 802.11a, 802.11b, 802.11g802.11 - 1997
    a - 1999
    b - 1999
    g - 2003
  49. 49What is 802.11d?Remember - D for Detail. Displays country codes
  50. 50What is 802.11i?Security - Introduction of WPA2, CCMP & AES also TKIP
  51. 51What is 802.11h?H for Home =Sofa...
    DFS (what is DFS, Dynamic Frequency Selection
    TPC (what is TPC? Transmit Power Control)
  52. 52What is 802.11kK for Kernel, management
    RRM - Radio Resource Management
  53. 53What is WiGig?60 Ghz
    802.11ad
    Limited to LOS
  54. 54What does ISI stand for? What is it?Intersymbol Interference
    Intersymbol interference is a signal distortion in telecommunication. One or more symbols can interfere with other symbols causing noise or a less reliable signal. The main causes of intersymbol interference are multipath propagation or non-linear frequency in channels.
  55. 55What is in 802.11-2012?fill in
  56. 56Whats new in 802.11 ac?- VHT. Below 6Ghz.
    -Wider channels
    -New modulation 256-QAM
    -More spatial streams (up to 8)
    -MU-MIMO, beamforming improvements
  57. 57Whats new in 802.11 af?-White Fi
    -54 MHz to 790 MHz
    -checks the available channels first
    -Unused TV frequencies
  58. 58What standards were post 802.11-2012?ac, af, aa, ae
  59. 59What are aa, ae?aa - enhancements to QoS MAC for robust Video & Audio streaming
    ae - enchancements to QoS. QMF - QoS Manatgement Frame
  60. 60What two things change the data rate from say 6 to 9 ?Modulation & coding technique
  61. 61What has OFDM introduced into it's coding?Error correction known as Convolutional Coding.
  62. 62What is FEC and what standard does it relate to ?Forward Error Correction - OFDM
  63. 63What does the Q in QAM and QPSK?Quadrature
    Quadrature Amp Modulation
    Quadrature Phase Shift Keying
  64. 64QAM relates to higher or lower data rates?Higher
  65. 65To not overlap channels on DSSS, HR-DSSS and OFDM, how much width do you need?DSSS - 30 MHz
    HR-DSSS - 25 MHz
    OFDM - 20 MHz
  66. 66What is the calculation for centre frequency in 5Ghz?36 x 5 = 180 + 5000 = 5180
  67. 67What is 802.11p?VISUAL: P for Police. Comms for high speed vehicles
  68. 68What is 802.11z ?VISUAL: Draw a Zed. Point to Point a Direct Link Setup - DLS.
    Allows frames to bypass their Access Point & communicate directly
  69. 69What is 802.11y ?Avoids interference between unlicensed and licensed frequencies
  70. 70What is 802.11w ?VISUAL: W for Warden
    Dos Attacks. Denial of Service.
    This is where Management Frame Protection comes in
  71. 71What is 802.11n ?HT - High Throughput. PHY & MAC enhancements
  72. 72What is 802.11v ?VISUAL: V for improVe
    Wireless Network Management (WNM)
    Exchange of information to IMPROVE overall performance
  73. 73What is 802.11s ?S. DS. Distribution System. From 802.11 to 802.3 Mesh Networking.
    VISUAL: meSh
  74. 74What does WDS stand for?Wireless Distribution System
  75. 75What is 802.11u ?WIEN - Wireless Internetworking with External Networks
    Network Discovery. Provision of emergency services.
    VISUAL: Draw a U, one side is int and one ext
  76. 76Write out 2.4GHz frequency spectrum with channel numbers2.412 go up in 5 MHz up to 2.472
    Channel 1-13
  77. 77Write out 5GHz frequency spectrum with channel numbers for UNII-1 LowerUp in 20 MHz
    36 - 5180
    40 - 5200
    44 - 5220
    48 - 5240
  78. 78Write out 5GHz frequency spectrum with channel numbers for UNII-2 MiddleUp in 20 MHz
    52 - 5260
    56 - 5280
    60 - 5300
    64 - 5320
  79. 79Write out 5GHz frequency spectrum with channel numbers for UNII-2 Extended5500, 5520, 5540, 5560, 5580, 5600, 5620, 5640, 5660, 5680, 5700
    Channels 100-140 up in 4
  80. 80What does UNII-2 onwards need to use?DFS, Dynamic Frequency Selection. Avoidance of Radar
  81. 81Write out 5GHz frequency spectrum with channel numbers for UNII-3 UpperChannels 149, 153, 157, 161
    5745
    5765
    5785
    5805
  82. 82What is a symbol?It is the state of the carrier.
    It’s defined as having a specific phase, magnitude, and frequency. The rate at which the carrier changes state from one symbol to the next is called the symbol rate.
  83. 83Ampify: What are fixed-gain and fixed-output?Fixed-gain - output of transceiver is increased by the amount of the amplification
    Fixed-output - does not add to the output of transceiver . It generates a signal which = the output of the amp regardless of power generated by transceiver. It matches it.
  84. 84How long is a BSSID address?48 Bit. It's the MAC of the radio
  85. 85What is an SSID? not what does it stand forLogical Network Name
  86. 86What is a BSA?Basic Service Area (Physical Coverage)
  87. 87What is nomadic roaming?Leave one BSA with no overlap and join another one
  88. 88How do you create a IBSS?Stations have to been on the same channel and use the same SSID
  89. 89What is a MP?Mesh Point
  90. 90What is WDS and how many MAC addresses does it use and what are they?Wireless Distribution System. It uses 4 MAC address frame formats, they are:
    1. Source
    2. Destination
    3. Transmitter
    4. Reciever
  91. 91What is an example of WDS?Bridging, Repeaters, Mesh (wireless backhaul)
  92. 92Draw a mesh...Draw it.
  93. 93How many components does a DS have?1. DSM (Distribution System Medium)
    Logical physical medium i.e 802.3
    2. DSS (Distribution System Services.
    Switch like intelligence in AP. Manages associations, dissassociations. Forwards to Layer 3-7
  94. 94What are and give examples of each: BSS ESS IBSS MBSSBSS - Basic Service Set (1 AP)
    ESS - Extended Service Set (2 or more APs)
    IBSS - Independant Basic Service Set (Airdrop)
    MBSS - Mesh Basic Service Set (AP to AP)
  95. 95What is WWAN, WMAN, WPAN, WLAN?Wireless Wide Area Network
    Wireless Metropolitan Area Network
    Wireless Personal Area Network
    Wireless Local Area Network
  96. 96What is 802.16?WiMax - WMAN
  97. 97What and where is MSDU & IS?MAC Service Data Unit: Upper layer info. Layers 3-7
    Integration Service - enables delivery of MSDUs between the DS and non 802.11 LAN via a portal. 802.11>802.3
  98. 98What is an ACK?Acknowledge. Delivery verification of a unicast frame
  99. 99What does 802.11n & 802.11ac use for ACK?Frame Aggregation. It groups multiple unicast frames. Delivery is verified by Block ACK.
  100. 100What do the acronyms CSMA/CA and CSMA/CD mean & do?CSMA/CA - Carrier Sense Multple Access/Collision Avoidance - used in 802.11
    CSMA/CD - Carrier Sense Multiple Access/Collision Detection
  101. 101Do Broadcast and Multicast frames need ACK?NO
  102. 102What are they? what do they do? DCF PCF HCFDynamic Coordinated Function - Hold off times before sending
    Point Coordinated Function - Polls clients about to transmit. P FOR POLL!!!!
    Hybrid Coordinated Function - Advanced QoS
  103. 103What is IFS? How many interframe spaces does IFS have?Interframe Space - Time that exists between transmission of Wireless frames
    Has 6 interframe spaces
  104. 104What do these stand for? RIFS SIFS PIFS DIFS AIFS EIFSReduced Interframe Space
    Short
    Point Coordinated Function
    Dynamic Coordinated Function
    Arbitration
    Extended
  105. 105What does a radio not receiving a ACK mean?Means that the Unicast is corrupt. The CRC will fail and wont send the ACK back. If the radio doesn't receive the ACK it will re-transmit.
  106. 106DCF has what four components?Interframe Space
    Duration/ID
    Carrier Sense
    Random Backoff Timer
  107. 107Acronym for RSPDAER idiculous
    S ome
    P eople
    D ont
    A lways
    E at
  108. 108What is duration in terms of IFS?How long the medium will be busy before another station can contend for the medium
  109. 109Carrier Sense is performed by which two technologies?Virtual Carrier Sense
    Physical Carrier Sense
  110. 110What is Virtual Carrier Sense and what layer does it operate at?Layer 2. It uses a timer mechanism known as the Network Allocation Vector (NAV)
    The NAV timer maintains a prediction of future traffic on the medium based on Duration value info seen in previous frame transmission
  111. 111How do NAV timers work, what does it mean to listening clients?Listening clients cant contend for the medium until the transmitting radios duration time has gone down to 0. They read the header of the frame (Duration field) and set their NAV timer to the period stated. Then they can contend.
  112. 112What is Physical Carrier Sense?It physically listens to the channel to see if other transmitters are taking up the channel.
    If the medium is busy, the radio will attempt to synchornise with the transmission.
    It determines is the medium is busy before transmitting. Known as CCA. CCA listens at Physical later, it must be clear before transmit
  113. 113When would Physical Carrier Sense be used?If a station did not hear another radio transmitting and was unable to read the duration field and set its NAV timer, PCS would come into play.
  114. 114What is a random back off timer for?Contending for the medium. It uses an algorithm to randomly choose a number from a range called Contention Window (CW). Number is chosen and x by the slot time.
    This is the final timer used by a station before it transmits
  115. 115What is Contention-Free Period (CFP) ?When an AP is functioning in PCF mode it is known as this as its polling the clients.
  116. 116What is special about HCF? and what amendement is it ?Allows radios to send multiple frames when transmitting on the medium. Multiple frames are referred to as Frame Bursts.
    HCF compliant radio gets a block of time for sending frames called Transmit Opportunity (TXOP).
    Amendment 802.11 e
  117. 117What is EDCA and what is it an extension of?Enhanced Distrubted Channel Access, it's an ext of DCF.
    Directs traffic to 4 QoS queus using priotiy tags at the MAC level.
  118. 118Who does the tagging work?From 802.3 it has it's 802.1Q header. Once received it reads the header and goes into its QoS queue.
  119. 119What are the four QoS queues?Voice (AC_VO), Video (AC_VI), Best Effort (AC_BE), Background (AC_BK)
  120. 120What are the two types of Block ACK?Immediate - Low latency traffic
    Delayed - Latency tolerant traffic
  121. 121What does a block of QoS frames also send with it?BlockAckReq - one response to say all frames were ACK and recieved
  122. 122WMM numbers the four QoS priority queues in what order?Voice 7,6
    Video 5,4
    Best Effort 0,3
    Background 2,1
  123. 123What is a analogy of airtime fariness?Allowing 5 young people down a slide, then 5 old, then 5 young etc instead of letting all 20 old people down when they come along.
  124. 124Virtual Carrier Sense is... Physical Carrier Sense is...VCS - NAV
    PCS - CCA
    PCS first as its physical
  125. 125What are the sub functions of HCF?EDCA HCCA
  126. 126What layer and sublayer can you find MSDU and what is it?Layer 2. MAC Sublayer. Payload that contains the IP packet and plus some LLC information.
  127. 127What do MSDU, MPDU stand for how does these work in the sub layers?MAC Service Data Unit. The LLC sends MSDU to the MAC Sublayer where it will add MAC header information to then become encapsulated to be a MPDU, basically a frame!
    MAC Protocol Data Unit
  128. 128Whats inside a MAC header?Frame control. MAC address information. Duration info.
  129. 129What is in the body of a frame?Data payload from the MSDU upper layer.
  130. 130What three sections are found in a MPDU?MAC Header
    Frame Body
    FCS (Frame Check Sequence)
  131. 131Draw a Frame! including the sublayers and headers added.MSDU adds LLC info in the LLC and then moves to MAC Sublayer where it gets a MAC header and FCS.
  132. 132FCS is also known as what? generic networking term....CRC - Cycle Redundancy Check
  133. 133What two sublayers is the Physical layer broken up into?PLCP & PMD
  134. 134What do PLCP & PMD mean?Physical Layer Convergence Procedure
    Physical Medium Dependent
    think: procedure dependent!
  135. 135Explain the relationship between PLCP, PMD and PPDU?Physical Layer Convergence Procedure takes the frame from MAC sublayer and prepare it for transmission by creating the Physical Layer Convergence Procedure Protocol Data Unit (PLCPDU or PPDU) and send it to Physical Medium Dependant for modulation
  136. 136What are the four sublayers of Layer 1 and 2?LLC
    MAC Sublayer
    PLCP
    PMD
  137. 137What are the three main major frame types?Management
    Control
    Data
  138. 138What are control frames for?Clear the channel.
    Acquire the channel.
    Provide unicast frame ACK
  139. 139What does RTS & CTS stand for?Request To Send
    Clear To Send
  140. 140What is Active and Passive scanning?Passive is where the client listens for beacon frames.
    Active is where the client sends a probe request (in management frame). They can or cannot contain SSID information
  141. 141What is the management frame called for Active Scanning?Probe Request.
    What is it called when it has the SSID information in it?
    Directed Probe Request
  142. 142Which is first Authentication or Authorisation?Authorisation
  143. 143How many 'ways' are Open Authentication and Shared Key Authentication?Open - two way
    Shared - four way
  144. 144what is an AID?Associtaion Identifier, found in the body of a association response frame. Numeric number of how many connected to BSS
  145. 145What is TIM?Traffic Indication Map
  146. 146Why would an AP buffer data on behalf of a station?For when it's in Power Save mode
  147. 147What does DTIM stand for? what does it do?Delivery Traffic Indication Map
    It sends out via a Beacon to wake all stations up at a certain time to receive Broadcast or Multicast addresses
  148. 148What is ATIM? Is it used with an AP, what kind of network?Announcement Traffic Indication Map
    NO its not Ad-hoc networks
  149. 149What is APSD? S-APSD & U-APSD. What are they? the broad termAutomatic Power Save Delivery
    Scheduled APSD
    Unscheduled APSD
    Enhanced Power Management Methods
  150. 150What is the goal of WMM-PSto have client devices spend more time in a dozed state consume less power. Also to minimise latency for time-sensitive such as Voice
  151. 151When would an AP send a TIM?When it has buffered unicast data for the client device. So it would send it out in a beacon. The client must send a PS-Poll frame to receive the frames.
  152. 152What are examples of the three telecommunication logical planes?Management - Network Monitoring
    Control - BGP or OSPF routing
    Data Plane - Physical Routers/Switches

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- CWNA Karteikarten am CWNA, erstellt von Michael Gleeson am 23/05/2016.
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