User's Manual

Appendix
BreezeNET PRO.11 Series 8-28 User’s Guide
8.5.4. How Does a Station Join an Existing Cell (BSS)?
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:
1. Passive Scanning: In this case the station just waits to receive a Beacon
Frame from the AP, (the beacon frame is a frame sent out periodically
by the AP containing synchronization information), or
2. Active Scanning: In this case the station tries to locate an Access Point
by transmitting Probe Request Frames, and waits for Probe Response
from the AP.
Both methods are valid. A method is chosen according to the power
consumption/performance trade-off.
8.5.4.1 The Authentication Process
Once the station has located an Access Point, and decides to join its BSS, it
goes through the Authentication Process. This is the interchange of
information between the AP and the station, where each side proves the
knowledge of a given password.
8.5.4.2 The Association Process
Once the station is authenticated, it then starts the Association Process,
which is the exchange of information about the station and BSS capabilities,
and which allows the DSS (the set of APs) to know about the current
position of the station). A station is capable of transmitting and receiving
data frames only after the association process is completed.
8.5.5. Roaming
Roaming is the process of moving from one cell (or BSS) to another without
losing connection. This function is similar to the cellular phones’ handover,
with two main differences:
1. On a packet-based LAN system, the transition from cell to cell may be
performed between packet transmissions, as opposed to telephony where
the transition may occur during a phone conversation, this makes the
LAN roaming a little easier, but