Method of transmitting a packet of digital data over a poly-phase power line affected by impulsive noise
The method transmits a long packet of digital data over a poly-phase power line affected by impulsive noise synchronous with phase voltages. Instead of using very complicated coding schemes, starting from the knowledge of the typical power line scenario, useful information is transmitted where noise synchronous with the main signal is absent. Time-intervals of a known or estimated duration during which the poly-phase power line is affected by impulsive noise are determined, and dummy data during the time-intervals, and useful data during other time-intervals free from impulsive noise, are transmitted.
1. A method of transmitting a packet of data over a poly-phase power line affected by impulsive noise synchronous with at least one phase voltage of the poly-phase power line, to be received by a receiver connected to the power line, the transmission of packet data lasting longer than the interval between two consecutive noise pulses on the power line, the method comprising:
identifying noise time-intervals of a duration during which the poly-phase power line is affected by the impulsive noise; and
transmitting dummy data during the identified noise time-intervals, and useful data during other time-intervals that are not affected by the impulsive noise.
2. The method of claim 1 , wherein the impulsive noise is synchronous with voltage peaks of the phase voltages.
3. The method of claim 2 , wherein identifying the noise time-intervals comprises:
detecting a zero-cross event of one of the phase voltages; and
estimating instants of occurrence of voltage peaks of one or more of the phase voltages with which the impulsive noise is synchronous from the zero-cross event;
the noise time-intervals including the estimated instants of occurrence of the voltage peaks.
4. The method of claim 1 , wherein transmitting includes:
transmitting a first group of data of a preamble portion and of a unique word for synchronizing a receiver;
transmitting a second group of data for identification of a transmission mode; and
transmitting a third group of useful information data and of dummy data.
5. The method of claim 4 , wherein the groups of data are transmitted so that the transmission of the first and second groups of data are in the other time-intervals that are not affected by the impulsive noise.
6. The method of claim 4 , further comprising transmitting, after the second group of data and before the third group of data, an auxiliary group of data for communicating to a receiver a number of useful information data that are transmitted between the second group of data and the dummy data, a number of dummy data that are periodically transmitted, and how the dummy data are interleaved with the useful information data.
7. A method of receiving useful data from a packet of data transmitted over a poly-phase power line affected by impulsive noise synchronous with at least a phase voltage of the poly-phase power line, the transmission of the packet of data lasting longer than the interval between two consecutive noise pulses on the power line, dummy data being transmitted during identified noise time-intervals, and useful data being transmitted during other time-intervals that are not affected by the impulsive noise, the method comprising:
at a receiver, identifying locations of dummy data and of useful data in the packet of data; and
at the receiver, extracting useful data by discarding data at the identified locations of dummy data.
8. The method of claim 7 , wherein the transmitted data include a first group of data of a preamble portion and of a unique word for synchronizing the receiver, a second group of data for identification of a transmission mode, and a third group of useful information data and of dummy data; wherein identifying locations of dummy data and of useful data is based on:
a number of useful information data that are transmitted between the second group of data and the dummy data; and
a number of dummy data that are periodically transmitted and how groups of dummy data are interleaved with groups of useful information data.
9. The method of claim 8 , wherein the transmitted data further comprises after the second group of data and before the third group of data, an auxiliary group of data for communicating to the receiver a number of useful information data that are transmitted between the second group of data and the dummy data, a number of dummy data that are periodically transmitted, and how the dummy data are interleaved with the useful information data; and wherein the auxiliary group of data is used in identifying the number of useful information data that are transmitted between the second group of data and the dummy data and in identifying the number of dummy data and how groups of dummy data are interleaved with groups of useful information data.
10. The method of claim 8 , further comprising:
identifying the transmission mode based upon the second group of data;
identifying locations of dummy data and of useful data, and extracting useful data by discarding data at the identified locations of dummy data when the transmission mode identified in the second group of data indicates the use of dummy data; and
extracting useful information data without discarding data when the transmission mode identified in the second group of data does not indicate the use of dummy data.
11. A communication device for transmitting a packet of data over a poly-phase power line affected by impulsive noise synchronous with at least a phase voltage of the poly-phase power line, to be received by a receiver connected to the power line, the transmission of the packet of data lasting longer than the interval between two consecutive noise pulses on the power line, the device comprising:
a power line interface; and
a data transmitter coupled to the power line interface and configured to identify noise time-intervals of a duration during which the poly-phase power line is affected by the impulsive noise, and to transmit dummy data during the identified noise time-intervals, and useful data during other time-intervals that are not affected by the impulsive noise.
12. The communication device of claim 11 , wherein the impulsive noise is synchronous with voltage peaks of the phase voltages.
13. The communication device of claim 12 , wherein the transmitter is configured to identify the noise time-intervals by detecting a zero-cross event of one of the phase voltages, and estimating instants of occurrence of voltage peaks of one or more of the phase voltages with which the impulsive noise is synchronous from the zero-cross event; wherein the noise time-intervals include the estimated instants of occurrence of the voltage peaks.
14. The communication device of claim 11 , wherein the data transmitter is configured to transmit:
a first group of data of a preamble portion and of a unique word for synchronizing a receiver;
a second group of data for identification of a transmission mode; and
a third group of useful information data and of dummy data.
15. The communication device of claim 14 , wherein the groups of data are transmitted so that the transmission of the first and second groups of data are in the other time-intervals that are not affected by the impulsive noise.
16. The communication device of claim 14 , wherein the transmitter is further configured to transmit, after the second group of data and before the third group of data, an auxiliary group of data for communicating to the receiver a number of useful information data that are transmitted between the second group of data and the dummy data, a number of dummy data that are periodically transmitted, and how the dummy data are interleaved with the useful information data.
17. A communication device for receiving a packet of data over a poly-phase power line affected by impulsive noise synchronous with at least one phase voltage of the poly-phase power line, the transmission of the packet of data lasting longer than the interval between two consecutive noise pulses on the power line, dummy data being transmitted during identified noise time-intervals, and useful data being transmitted during other time-intervals that are not affected by the impulsive noise, the device comprising:
a power line interface; and
a data receiver coupled to the power line interface and configured to identify locations of dummy data and of useful data in the packet of data, and extract useful data by discarding data at the identified locations of dummy data.
18. The communication device of claim 17 , wherein the transmitted data include a first group of data of a preamble portion and of a unique word for synchronizing the receiver, a second group of data for identification of a transmission mode, and a third group of useful information data and of dummy data; wherein the data receiver is configured to identify locations of dummy data and of useful data by using:
a number of useful information data that are transmitted between the second group of data and the dummy data; and
a number of dummy data that are periodically transmitted and how groups of dummy data are interleaved with groups of useful information data.
19. The communication device of claim 18 , wherein the transmitted data further comprises after the second group of data and before the third group of data, an auxiliary group of data for communicating a number of useful information data that are transmitted between the second group of data and the dummy data, a number of dummy data that are periodically transmitted, and how the dummy data are interleaved with the useful information data; and wherein the data receiver is configured to use the auxiliary group of data in identifying the number of useful information data that are transmitted between the second group of data and the dummy data and in identifying the number of dummy data and how groups of dummy data are interleaved with groups of useful information data.
20. The communication device of claim 18 , wherein the data receiver is further configured to:
identify the transmission mode based upon the second group of data;
identify locations of dummy data and of useful data, and extracting useful data by discarding data at the identified locations of dummy data when the transmission mode identified in the second group of data indicates the use of dummy data; and
extract useful information data without discarding data when the transmission mode identified in the second group of data does not indicate the use of dummy data.