Receiver
Sender
PFS
Data pending
Neighbor(1)
PFS
Neighbor(2)
PFS
TFS
Data
ACK
Listen
Standby active
PFS
Back-off
···
···
···
m∗TDP
Figure 5: SpeckMAC-D.
Receiver
Sender
Data pending
Beacon
Data pending
Neighbor(1)
Neighbor(2)
PBS
PBS
···
···
TDPT
TBS
TDT
Data
Standby active Back-off
Figure 6: RI-MAC.
And푇reqis equal to푇resp. So the total aggregation time of푛
nodes per request is
푇SPECK-MAC-D(푅)=푇req+푛∗푇resp
=(푛+1)∗푇req=(푛+1)∗(푇퐵+푇DP∗푚).
(20)
4.6. RI-MAC.RI-MAC is a representative receiver-initiated
LPL protocol. Each RI-MAC device basically performs
periodic beacon sending (PBS). A sender first switches to
reception (RX) mode and waits to receive the beacon of a
corresponding receiver. As soon as a corresponding beacon is
received, the sender transmits data and then goes back to PBS.
The receiver of the data acknowledges a beacon, as shown in
Figure 6.
4.6.1. Periodic Report.The report time of an RI-MAC device
is as follows:
푇resp=푇DT+2∗푇BS. (21)
Therefore, the total report time of푛nodes is
푇RI-MAC(푃)=푛∗푇resp=푛∗(푇DT+2∗푇BS). (22)
4.6.2. Request-Oriented.The required time for a concentrator
to transmit its request to devices is
푇req=푇DT+2∗푇BS. (23)