How Does A Station Join An Existing Cell; Figure 9-17. Access Mechanism - Alvarion BreezeNET PRO.11 Series User Manual

Exponential Back-off means that each time the station chooses a slot and happens
to collide, it will increase the maximum number for the random selection
exponentially.
The 802.11 standard defines an Exponential Back-off Algorithm, that must be
executed in the following cases:
When the station senses the medium before the first transmission of a packet,
and the medium is busy
After each retransmission, and
After a successful transmission
The only case when this mechanism is not used is when the station decides to
transmit a new packet and the medium has been free for more than DIFS.
The following figure shows a schematic of the access mechanism:

9.5.4 How Does a Station Join an Existing Cell

When a station wants to access an existing BSS (either after power-up, sleep mode,
or just entering the BSS area), the station needs to get synchronization information
from the Access Point (or from the other stations when in ad-hoc mode, which will
be discussed later).
The station can get this information by one of two means:
BreezeNET PRO.11

Figure 9-17. Access Mechanism

9-33
Appendix
User's
Guide