System and methods for synchronizing edge devices on channels without carrier sense
A system and method are disclosed for synchronizing edge devices on a network, wherein the network has limited bandwidth and does not support a practical carrier sense mechanism. The edge devices transmit, using a slotted protocol, to a server located at a central data aggregation point. The server also controls a Central Transmitter, which sends messages to the edge devices to assign transmission slots and provide timing information to the edge devices to ensure that transmissions sent by devices sharing the same communication channel do not collide.
1. A system for synchronizing an intelligent communicating device (ICD) on an electrical distribution grid, comprising:
a Central Transmitter (CT) configured to be coupled to the electrical distribution grid on a high voltage side of a transformer; and
an ICD comprising a clock and configured to be coupled to the electrical distribution grid on a low voltage side of the transformer;
wherein:
the CT is configured to transmit a plurality of master frame announcements (MFAs) at arbitrary times through the transformer to the ICD, each MFA identifying a time of transmission of the respective MFA and a future time of a corresponding master frame, the corresponding master frame comprising a plurality of time slots, each time slot associated with a particular ICD of a plurality of ICDs; and
the ICD is configured to:
receive one MFA of the plurality of MFAs;
based on the time of transmission of the one MFA and the future time of the corresponding master frame, synchronize the clock;
await the future time of the corresponding master frame; and
transmit data on the electrical distribution grid to the high voltage side of the transformer in a time slot of the corresponding master frame that is associated with the ICD.
2. The system of Claim 1 , where the CT is an on-grid transmitter.
3. The system of claim 1 , where the CT is a private radio transmitter.
4. The system of claim 1 , where the CT is simulated by a wireless two-way network.
5. The system of claim 1 , wherein the ICD comprises a receiver configured to communicate with a type of the CT.
6. The system of claim 1 , wherein the CT is controlled by a software system comprising a Broadcast Queue Server, a Broadcast Transmission Queue and a Broadcast Server.
7. The system of claim 1 , wherein the electrical distribution grid lacks a carrier sense.
8. The system of claim 1 , wherein the plurality of MFAs are transmitted on a broadcast channel, and the ICD transmits the data upstream through the transformer on an edge-to-aggregation-point channel that is a different channel than the broadcast channel.
9. A system for synchronizing an intelligent communicating device (ICD) on an electrical distribution grid, comprising:
a server comprising a processor, the server configured to:
maintain, on a high voltage side of a transformer, a queue of messages, at least one of the messages comprising a master frame announcement (MFA) that identifies a future time of a corresponding master frame, the corresponding master frame comprising a plurality of time slots, each time slot associated with a particular ICD of a plurality of ICDs located on a low voltage side of the transformer; and
an ICD configured to:
request, via a communication medium other than the electrical distribution grid, the messages from the queue of messages;
receive the MFA:
receive synchronization information to synchronize a clock of the ICD;
await the future time of the corresponding master frame; and
transmit data on the electrical distribution grid to the high voltage side of the transformer in a time slot of the corresponding master frame that is associated with the ICD.
10. The system of claim 9 wherein to receive the synchronization information to synchronize the clock of the ICD, the ICD is further configured to request, from a synchronous central system time, a current time.
11. The system of claim 9 wherein to receive the synchronization information to synchronize the clock of the ICD, the ICD is further configured to:
receive in the MFA a time identifier that identifies a future time of a timing pulse;
receive the timing pulse; and
set the clock of the ICD to the future time in response to receiving the timing pulse.
12. A method for synchronizing an intelligent communicating device (ICD) on an electrical distribution grid, comprising:
transmitting, by a Central Transmitter (CT) coupled to the electrical distribution grid on a high voltage side of a transformer, a plurality of master frame announcements (MFAs) at arbitrary times through the transformer to a plurality of ICDs that receive power from the transformer, each respective MFA identifying a time of transmission of the respective MFA and a future time of a corresponding master frame, the corresponding master frame comprising a plurality of time slots, each time slot associated with a particular ICD of the plurality of ICDS;
receiving, by a first ICD of the plurality of ICDs, one MFA of the plurality of MFAs, the first ICD comprising a clock and coupled to the electrical distribution grid on a low voltage side of the transformer;
based on the time of transmission of the one MFA and the future time of the corresponding master frame, synchronizing the clock;
awaiting the future time of the corresponding master frame; and
transmitting, by the first ICD, data on the electrical distribution grid to the high voltage side of the transformer in a time slot of the corresponding master frame that is associated with the first ICD.
13. The method of claim 12 , further comprising receiving, at a server coupled to the CT, a plurality of messages from a plurality of different applications, wherein some of the plurality of messages comprise respective MFAs of the plurality of MFAs.
14. The method of claim 13 , further comprising reprioritizing the plurality of messages to prioritize the plurality of MFAs based on a Contractual Maximum Wait Time.
15. The method of claim 13 , further comprising notifying an application of the plurality of different applications that a message of the plurality of messages cannot be broadcast before a Contractual Maximum Wait Time has elapsed.
16. The method of claim 12 , wherein the first ICD will cease to transmit if, at the end of a Master Frame, the first ICD has not received a Master Frame Announcement announcing a time of a next Master Frame.
17. A method for synchronizing an intelligent communicating device (ICD) on an electrical distribution grid, comprising:
maintaining, on a server on a high voltage side of a transformer, a queue of messages, at least one of the messages comprising a Master Frame Announcement (MFA) that identifies a future time of a corresponding master frame, the corresponding master frame comprising a plurality of time slots, each time slot associated with a particular ICD of a plurality of ICDs located on a low voltage side of the transformer;
requesting, by an ICD of the plurality of ICDs via a communication medium other than the electrical distribution grid, the messages from the queue of messages;
receiving, by the ICD, the MFA;
receiving, by the ICD, synchronization information to synchronize a clock of the ICD;
awaiting the future time of the corresponding master frame; and
transmitting, by the ICD, data on the electrical distribution grid to the high voltage side of the transformer in a time slot of the corresponding master frame that is associated with the ICD.
18. The method of claim 17 , further comprising assigning each message of the plurality of messages a monotonically increasing message sequence number unique to the queue.
19. The method of claim 18 , further comprising maintaining an inventory of the plurality of ICDs.
20. The method of claim 19 , further comprising associating with an inventory record of each ICD a highest message sequence number which each ICD has already received.
21. The method of claim 20 , wherein requesting, by the ICD of the plurality of ICDs via the communication medium other than the electrical distribution grid, the messages from the queue of messages further comprises periodically requesting, by the ICD of the plurality of ICDs via the communication medium other than the electrical distribution grid, the messages from the queue of messages.
22. The method of claim 21 , further comprising providing, in response to a request from the ICD, messages in the queue which have a higher message sequence number than a highest message sequence number associated with the ICD.
23. The method of claim 22 , further comprising updating, the inventory record of said ICD with the highest message sequence number transmitted to said ICD.
24. The method of claim 23 , further comprising removing from the queue each message which has a lower message sequence number than a highest message sequence number of each ICD of the plurality of ICDs.
25. The method of claim 17 , further comprising removing from the queue messages which have resided in the queue for longer than a predefined number of polling cycles, where a polling cycle is an interval of time in which all ICDs of the plurality of ICDs are expected to have polled once.
26. The method of claim 17 , wherein receiving, by the ICD, the synchronization information to synchronize the clock of the ICD comprises requesting, from a synchronous central system time, a current time.
27. The method of claim 17 , wherein an alternative protocol is used to synchronize a plurality of clocks of the plurality of ICDs.
28. The method of claim 17 , wherein receiving, by the ICD, synchronization information to synchronize the clock of the ICD comprises:
receiving in the MFA a time identifier that identifies a future time of a timing pulse;
receiving the timing pulse; and
setting the clock of the ICD to the future time in response to receiving the timing pulse.
29. The method of claim 17 , wherein each ICD initiates a polling cycle of the each ICD with a different offset from the master frame than any other ICD of the plurality of ICDs.