Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
4.3.8 Access Frame
S
O
T
CSMA Token
CSMA PPDU
IPPDUS1
P0min
P0max P1min
Backoff
slot time
Backoff time
CONTENTION WINDOW
P1max P2min
P2max P3min
Submission page 102 UPA-OPERA
S
O
T
PPDU
Contention winner Node
P3max
Token
Figure 33: Use of CSMA Token to assign channel time to the contention winner node
A master shall periodically transmit Access tokens inviting Unregistered slaves or Registered slaves that want
to change masters to subscribe to the network. An Access Token does not have a specific destination, and thus it
is possible that no slave will answer to this request. Upon receiving an access frame, an Unregistered slave or a
Registered slave that decides to reply must send an access reply frame as described in 4.3.6.
4.3.9 Access Reply Frame
The access reply frame is sent by an Unregistered slave that wishes to enter the network, or a Registered slave
that wishes to change its current master. The transmission of an Access Reply Frame is triggered by the
reception of an Access Frame.