ReceiverSenderPFSData pendingNeighbor(1)PFSNeighbor(2)PFSTFSDataACKListenStandby activePFSBack-off·········m∗TDPFigure 5: SpeckMAC-D.ReceiverSenderData pendingBeaconData pendingNeighbor(1)Neighbor(2)PBSPBS······TDPTTBSTDTDataStandby active Back-offFigure 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 is푇RI-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 is푇req=푇DT+2∗푇BS. (23)