Method and apparatus for impulse noise mitigation for power line networking

Abstract

A method and apparatus for impulse noise mitigation. In one embodiment, the method comprises identifying one or more impulse noise affected samples of a communication signal transmitted via power line communications; creating, based on the identified one or more impulse-noise affected samples, one or more erasures; and adaptively controlling a correlation threshold for packet preamble detection, wherein the correlation threshold is adaptively controlled based on the one or more erasure.

The invention claimed is: 
     
       1. A method for impulse noise mitigation, comprising:
 identifying one or more impulse noise affected samples of a communication signal transmitted via power line communications; 
 creating, based on the identified one or more impulse noise affected samples, one or more erasures; and 
 adaptively controlling a correlation threshold for packet preamble detection, wherein the correlation threshold is adaptively controlled based on the one or more erasures. 
 
     
     
       2. The method of  claim 1 , wherein creating the one or more erasures comprises marking each impulse noise affected sample of the one or more impulse noise affected samples. 
     
     
       3. The method of  claim 2 , wherein identifying the one or more impulse noise affected samples comprises:
 receiving a plurality of samples of the communication signal; 
 determining when a number of consecutive samples of the plurality of samples are each less than a gain sample threshold; 
 computing a first moving average based on the consecutive samples; 
 computing a second moving average based on samples of the plurality of samples that are less than the gain sample threshold; 
 comparing the first moving average to an erasure threshold that is based on the second moving average; and 
 identifying, when the first moving average is greater than the erasure threshold, the one or more impulse noise affected samples. 
 
     
     
       4. The method of  claim 3 , wherein adaptively controlling the correlation threshold comprises computing the correlation threshold based on a number of erasures in a preamble-length window. 
     
     
       5. The method of  claim 4 , further comprising performing a cross-correlation between the plurality of samples and a known sequence, wherein each erasure of the one or more erasures is treated as a zero during the cross-correlation. 
     
     
       6. The method of  claim 5 , further comprising:
 comparing a result of the cross-correlation to the correlation threshold; and 
 identifying a packet preamble when the result of the cross-correlation is greater than the correlation threshold. 
 
     
     
       7. The method of  claim 6 , wherein performing the cross-correlation comprises performing a hard decision cross-correlation. 
     
     
       8. The method of  claim 3 , further comprising:
 comparing the first moving average to a length threshold; and 
 when the first moving average is equal to the length threshold, replacing previous samples in a first moving average ramp-up window by the first moving average. 
 
     
     
       9. The method of  claim 3 , wherein the erasure threshold is equal to the second moving average plus a margin value. 
     
     
       10. An apparatus for impulse noise mitigation, comprising:
 an erasure detection for packet detector (EDPD) module for (i) identifying one or more impulse noise affected samples of a communication signal transmitted via power line communications; (ii) creating, based on the identified one or more impulse noise affected samples, one or more erasures; and (iii) adaptively controlling a correlation threshold for packet preamble detection, wherein the correlation threshold is adaptively controlled based on the one or more erasures. 
 
     
     
       11. The apparatus of  claim 10 , wherein the EDPD module comprises an impulse noise erasure detector module for marking each impulse noise affected sample of the one or more impulse noise affected samples to create the one or more erasures. 
     
     
       12. The apparatus of  claim 11 , wherein the EDPD module receives a plurality of samples of the communication signal and the impulse noise erasure detector module identifies the one or more impulse noise affected samples by:
 determining when a number of consecutive samples of the plurality of samples are each less than a gain sample threshold; 
 computing a first moving average based on the consecutive samples; 
 computing a second moving average based on samples of the plurality of samples that are less than the gain sample threshold; 
 comparing the first moving average to an erasure threshold that is based on the second moving average; and 
 identifying, when the first moving average is greater than the erasure threshold, the one or more impulse noise affected samples. 
 
     
     
       13. The apparatus of  claim 12 , wherein the EDPD module comprises a packet detector module that adaptively controls the correlation threshold by computing the correlation threshold based on a number of erasures in a preamble-length window. 
     
     
       14. The apparatus of  claim 13 , wherein the packet detector module further performs a cross-correlation between the plurality of samples and a known sequence, wherein each erasure of the one or more erasures is treated as a zero during the cross-correlation. 
     
     
       15. The apparatus of  claim 14 , wherein the packet detector module further compares a result of the cross-correlation to the correlation threshold; and identifies a packet preamble when the result of the cross-correlation is greater than the correlation threshold. 
     
     
       16. The apparatus of  claim 15 , wherein performing the cross-correlation comprises performing a hard decision cross-correlation. 
     
     
       17. The apparatus of  claim 12 , wherein the impulse noise erasure detector module further compares the first moving average to a length threshold and, when the first moving average is equal to the length threshold, replaces previous samples in a first moving average ramp-up window by the first moving average. 
     
     
       18. The apparatus of  claim 12 , wherein the erasure threshold is equal to the second moving average plus a margin value. 
     
     
       19. A system for mitigating power line communication impulse noise, comprising:
 a plurality of renewable energy sources; 
 a plurality of inverters coupled to the plurality of renewable energy sources in a one-to-one correspondence, wherein the plurality of inverters is coupled to a power line; and 
 a plurality of power line communication transceivers (PLCT) coupled to the plurality of inverters in a one-to-one correspondence, wherein the plurality of PLCTs is coupled to the power line and wherein each PLCT of the plurality of PLCTs comprises an erasure detection for packet detector (EDPD) module for (i) identifying one or more impulse noise affected samples of a communication signal transmitted via power line communications; (ii) creating, based on the identified one or more impulse noise affected samples, one or more erasures; and (iii) adaptively controlling a correlation threshold for packet preamble detection, wherein the correlation threshold is adaptively controlled based on the one or more erasures. 
 
     
     
       20. The system of  claim 19 , wherein the plurality of renewable energy sources is a plurality of photovoltaic (PV) modules.