A low SNR approach to Substation Communication using Powerline for EMI reduction

Use of space time code concatenated with BCH (Bose Choudhari Hocquenghem) code is analyzed for performance in powerline channel with impulse noise. Performance of BCH-Space time code is worked in this paper for application of narrowband power line communication. BCH code (63, 36) with t=5 is designed and implemented in TMS320C6713 Digital Signal Processor, which is interfaced with Matlab version 7.4, where power line channel and impulse noise are simulated. These results are compared with Turbo coded OFDM scheme for powerline channel. From the results, reduction in carrier power requirement is found for BCH Space time code. Space time code has now become popular in wireless communication, as application in multipath channel. Since power line can provide different uncorrelated paths to realize multipaths effect, it is possible to apply space time code for powerline channel. In this paper, powerline is modelled as a multipath channel and impulse noise as Middleton class-A noise, on Matlab 7.4 platform. The BCH code of n=63, k=36, t=5, is designed and tested in a Digital Signal Processor (DSP) TMS320C6713. Interfacing is done using JTAG from processor to Matlab where power line, impulse noise and space time code are simulated. The performance of the system as communication system for narrowband PLC is tested for different channel and noise conditions. The results are used to find SNR requirement at a Pe (Probability of error) of the order of 10-5 and for carrier signal strength to be within EMI (Electro Magnetic Interference) and EMC(Electro Magnetic compatibility) limits. Use of a BCH code with more better error correcting capacity, will further reduce the SNR requirement, hence will reduce carrier power.