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

4-June-07 P1901_PRO_016_r0
MASTER
DISTRIBUTOR
TOKEN
Slave 1
Slave 4
Slave 3
Slave 2
Check Slave 1 starts
transmitting
Check Slave 1 releases
token before Validity1
DATA TOKEN
to Slave 4
Slave 4 does not start
transmitting after Slave 1
transmission. Transmit
new Distributor Token
Token lost
Check Slave 4 releases
token before Validity2
timeout
Check Slave 4 starts
transmitting
DISTRIBUTOR
TOKEN
DATA
TOKEN to Slave 3
Check Slave 3 releases
token before Validity3
timeout
Check Slave 3 starts
transmitting
Check Slave 2 starts
transmitting
DATA
TOKEN to Slave 2
Figure 52: Recovery Token Lost by Master node
Check Slave 2 returns
token before Validity4
timeout
DATA TOKEN
to MASTER
DISTRIBUTOR
TOKEN
2. Each node on the distribution list transmits in its assigned slot time if it does not receive the token from the
previous node on the distribution list.
In this mode, nodes on the distribution list needs to receive the Distributor Token to know when they have
to transmit. Upon the reception of a Distributor token, each node starts transmitting in their slot time if the
previous node on the list does not assign to it the channel. If previous node on the list ends transmitting, it
assigns the channel to the subsequent node on the list. If this token is lost, next node shall start transmitting
in its slot time.
This mode can be very dangerous because if all the nodes on the distribution list lose the Distritubor token,
Master node does not transmit till the end of the total channel time assigned in that token.
From the other hand, this mode can be very interesting in a scenario with no visibility between slave nodes.
In that case, slave nodes cannot assign the channel to the next node on the list because they have no direct
visibility. This functionality reduces the overhead due to the Master does not transmit to assign the channel
to the next node.
Submission page 130 UPA-OPERA