WLAN

Question 1

What are the 802.11 Mac requirements

Answer 1

Support multiply PHYs
Should allow overlap of multiple networks in the same area.
Robust for interferience
Mechanism to deal with Hidden nodes
Privacy and access control

Question 2

Basics of IEEE 802.11 Protocols

Answer 2

-Use distributed coordination function for efficient medium sharing (CSMA/CA)
-Robust for interferience:
CSMA/CA with ACK for unicast frames.
-Parameterized use of RTS and CTS to provide a virtual Carrier Sense function protect against hidden nodes.

Question 3

Key technical

Answer 3

Co-existence with other devices sharing the 2.4 and 5GHz bands
Maximaze spectral efficiency and performance
Specifications for the PHY and MAC layer.
Backward compatibility with legacy 802.11 standard.

Question 4

802.11a

Answer 4

5GHz 
TP: 23Mbps  
Raw Data Rate: 54Mbps
Range 35 to 120m
OFDM (64 subcarriers)
20MHz channel spacing

Question 5

802.11b

Answer 5

2.4GHz
TP: 4.3Mbps
Raw Data Rate: 11Mbps
Range 38 to 140m

Question 6

802.11g

Answer 6

2.4GHz
TP: 19Mbps
Raw Data Rate: 54Mbps
Range 38 to 140m

Question 7

802.11n

Answer 7

2.4 , 5GHz 
TP: 74Mbps  
Raw Data Rate: 248Mbps
Range 70 to 250m
Key features: MIMO
40MHz carriers (number of carriers slightly doubled)
LDPC

Question 8

802.11s (Mesh)

Answer 8

Mesh Point (MP) establishes peer links with MP neighbors
Mesh AP functionality of a MP, collocated with AP which provides BSS services
Mesh Portal: Point at which MSDUs enter and leave a WLAN Mesh.
-MUltihop