Flashcards
Chapter 11
Cards in this deck (23)
- 1What are some of the benefits of MIMO?Reduce coverage holes
2 Spatial streams
Frame aggregation
Mixed client environments - 2What do these stand for? TxBF MRC SM STBC CSDTxBF - Transmit Beamforming
MRC - Maximal Ratio Combining
SM - Spatial Multiplexing
STBC - Space Time Blocking Coding
CSD (Cylic Shift Diversity) - 3What are the physical enhancements that HT brings in MIMO?40 MHz Channels
More Subcarriers
Channel Bonding
Non-HT Duplicate Format
Short GIs
Modulation Rates
Antenna Selection - 4What are the MAC enhancements that HT brings in MIMO?Frame aggregation
Block Acknowledges
RIFS
SMPS
PSMP - 5Enhancements with VHT?TxBF
MU-MIMO
Max 8 spatial streams - 6Enhancements with PHY for VHT?256-QAM
5GHz only
80/160 MHz channels - 7What does ADC and DAC mean?ADC - Analogue Digital Convertor (Rx)
DAC - Digital Analogue Convertor (Tx) - 8What does MRC stand for & do?Maximal Ratio Combining (Key word combine for Rx)
Takes multiple received signals (Multipath) + combines them in a way that significantly boosts strength - 9What is SM?Spatial Multiplexing
Instead of single stream for communications the info is split and transmitted over multi streams (requires MIMO client to do this) - 10How many subcarriers in: 802.11 a/g 802.11 n w/ 20 MHz channel 802.11 n w/ 40 MHz channel802.11 a/g - 52
802.11 n w/ 20 MHz channel - 56
802.11 n w/ 40 MHz channel - 114 - 11What is the standard Guard Interval?800 nanoseconds
- 12What is the optional shorter GI (SGI) ? what are the benefits and negatives of it?400 nanoseconds
Benefit: High Transmission Rate
Negative: Can cause Intersymbol Interference - 13What does Frame Aggregation do? What is an analogy of this?Combines multiple data units into one frame. Saves on the HT & MAC overhead.
Analogy: Putting more people in a car, more efficient than single people in individual cars - 14What does A-MSDU stand for?Aggregate-MAC Service Data Unit
- 15What is an analogy of A-MSDU? What layer does it happen?3 letters going to the same person can be put into one bigger envelope and not individual small ones. More efficient. Data Link Layer.
- 16What does A-MPDU stand for?Aggregate-MAC Protocol Data Unit
- 17What is an analogy of A-MPDU?Letters going to the same address but for different people so they all need their own names shown (MAC header). They get put into a big envelope like a postmans sack (PLCP Header)
- 18Analogy of a Block Ack?You respond to say you received all the letters and you didn't respond to the individual letters everytime.
- 19Write out all the Interframe Spaces....S ome - SIFS
P eople - PIFS
D ance - DIFS
A ll - AIFS
E vening - EIFS
R eally - RIFS - 20What do these mean? SIFS PIFS DIFS AIFS EIFS RIFSShort Interframe Space
PCF (Point Coordinated Function IFS)
DCF (Distributed Coordinated Function IFS)
Arbitrary Interframe Space
Extended Interframe Space
Reduced Interframe Space - 21What are the PPDU frame formats?STF (Short Training Field)
LTF (Long Training Field)
SIG (Signal) - 22What are the four protection modes?0 - No protection
1- HT non-member protection
2 - HT 20 MHz
3 - Non-HT Mixed Mode (most common) - 23What are the 802.11ac enhancements?only 5 GHz
256 QAM Modulation
MU-MIMO
TxBF
VHT
80/160 MHz available
8 Spatial Stream
RTS/CTS used across multi channels
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- CWNA CWNA Online Flashcards on Chapter 11, created by Michael Gleeson on 27/02/2017.
- Created by
- Michael Gleeson · Feb 2017
- Updated
- Feb 28, 2017
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