Because it is a beginner, many terms have kept in English, and they don't dare to mislead.
Some professional terms on the picture
BSS: Basic Service Set
AP: Access Point (also known as Base Station)
Ess: Extended Service Set
Distributed System: Typical Ethernet
A complete interconnected WLAN will include different BSSs and their respective APs, Distribution System. Portal concept: A device connecting two 802.11 lan. THIS IS An Abstract Description of Part of The FunctionAry OF A "Translated Bridge".
Hierarchical description of 802.11
FH: frequency hopping
DS: DIRECT SEQUENCE
IR: Infrared
The MAC layer handles conventional MAC transactions, and also deal with the functions of some upper protocols, such as Fragmentation, Packet Retransmissions, Acknowledge ...
The MAC layer defines two ways:
Distributed Coordination Function
Point Coordination Function
Basic access: CSMA / CA
CSMA / CA: Carrier Sense Multiple Access with Collision Avoandence carrier monitor multi-point access / avoid collision
In Ethernet, most commonly used CSMA / CD (CD = Carrier Detection conflicts detection)
CSMA protocol work mode
Why use CSMA / CA instead of CSMA / CD?
CSMA / CD
It is necessary to send reception, which requires the sending and reception, which will increase investment; in the wireless environment, all sites cannot be ensured (this is
CD
Basic hypothesis of the mechanism thus causing the site to be sent to detect the route, it means that the line is idle within the received range.
80
2
.
11
used
CA
One
Positive Acknowledge Scheme:
IF line busy THEN latency
IF idle THEN send, acceptor CRC check, send ACK feedback
If there is no ACK, THEN retransmits until the maximum number of retransmits
Else receives ACK, successful transmission, no conflict
Virtual Carrier Sense
Reference:
CSMA / CA protocol
