Introduction:Within a smart grid, we seek to enable higher data rate monitoring and control applications for making homes and small businesses more efficient in their use of energy. We focus on the “last mile” of power delivery from a concentrator to its local area subscribers along low-voltage lines, for enabling applications such as automatic meter reading, device-specific billing and smart energy management.

Among communication standards for low-voltage power networks, G3 and PRIME transmit data using multiple carrier frequencies, a.k.a. orthogonal frequency division multiplexing (OFDM). PRIME uses a transmission band of 40-90 kHz and delivers up to ~128 kbps from subscriber to concentrator.The availability of three phases on low-voltage lines and three copper wires (i.e. phase, neutral and ground) in the inhome single-phase power systems allows potentially higher achievable data rates. However, the presence of cross-talk induced by energy coupling across the phases or wires may cause significant degradation in achievable data rate. In this project, we develop adaptive digital signal processing methods and real-time prototypes to increase bit rates in power networks. We will quantify the communication performance vs. computational complexity tradeoffs in a real-time multi-channel (MIMO) powerline communication testbed.

Past Work:We have implemented a real-time 2x2 MIMO OFDM testbed for a wired communication system. The testbed contains multiple algorithms for common multicarrier transceiver structures such as peak-to-average power ratio (PAPR) reduction, channel equalization, bit allocation, crosstalk cancellation and channel tracking. We have doubled the bit rates over the single-cable (1x1) system. We will extend the testbed to prototype a MIMO powerline communication system in order to study the design tradeoffs of various beamforming, spatial multiplexing and receiver diversity strategies, and of receiver algorithms to combat powerline channel impairments.


Ongoing Research:We are developing a 1x1 powerline communication (PLC) prototype by tailoring our existing OFDM wired testbed.The transceiver solution is coded as a C++ dynamically linked library (DLL) and run by National Instruments (NI) embedded hardware. The input/output management and graphical user interface (GUI) is in NI LabVIEW.The testbed can execute in real time over physical cables, or simulate on the PC using cable models.

Powerline channel is a hostile environment for data transmission. By transmitting independently over multiple subcarriers, OFDM is ableto cope with the frequency-selective channel. The OFDM demodulation by discrete Fourier transform spreads out the impulsive noise. To enable more robust and efficient communication, adaptive signal processing methods will be developed:

  1. Peak-to-average power ratio reduction;
  2. Channel shortening equalization to compensate for extra-long delay spread;
  3. Bit allocation;
  4. Statistical estimation and mitigation of impulsive noise and narrow-band interference.