Engineers at Penn State have developed techniques for increasing the data rate for broadband over power lines (BPL) close to one Gbps per kilometer, compared with the two to three Mbps rate achieved in recent BPL field tests. Dr. Mohsen Kavehrad, the W. L. Weiss professor of electrical engineering and director of the Center for Information and Communications Technology Research at Penn State University heads the research effort. These techniques, so far, have only been tested in computer simulations. The higher data rate is achieved by conditioning the power lines to reduce the impedance discontinuities at the junctions and branches in the electrical grid. Uncorrected, these discontinuities create a multipath-like effect on the lines, decreasing data transmission capability. Kavehrad said, "The signal can bounce back and forth in the lines if there is no proper impedance matching. The bouncing takes energy away from the signal and the loss is reflected in the ultimate capacity. In service, performance will depend on how close the power company chooses to place the repeaters."
Commenting on the research, Dr. Kavehrad said, "We've run a computer simulation with our new power line model and found that, under ideal conditions, the maximum achievable bit rate was close to a gigabit per second per kilometer on an overhead medium voltage unshielded U.S. electric power line that has been properly conditioned through impedance matching. The gigabit can be shared by a half dozen homes in a neighborhood to provide rates in the hundreds of megabits per second range, much higher than DSL and even cable."
In the Penn State press release Power line data transmission capacity: Bigger than DSL or cable, there was no mention of the spectrum required to achieve these high data rates nor was there any discussion of how these techniques would impact interference to other users of the spectrum from BPL. While better impedance matching should reduce interference somewhat on any given frequency, greater bandwidth demands could make it more difficult to notch out frequencies that cause interference to nearby receivers. It would be interesting to see the radiated RF emission levels predicted using the computer simulation.
Unfortunately, the paper describing the research, "Transmission Channel Model and Capacity of Overhead Multi-conductor Medium-Voltage Power-lines for Broadband Communications," by P. Amirshahi and M. Kavehrad was not found online. It was presented at the IEEE Consumer Communications and Networking Conference taking place with the recent Consumer Electronics Show in Las Vegas.
