OFDM-based distributed estimation for rich scattering environments

A preliminary investigation has been conducted into the use of orthogonal frequency-division multiple-access for distributed estimation. The key difference from previous work in the literature is that the channels between the sensors and the fusion center contain multiple paths with time lags, amplitudes, and phase rotations due to fading. Orthogonal frequency-division multiplexing has been proven to be an effective modulation scheme in the presence of multipath channels, and thus has been utilized in these experiments. This estimation system was designed to operate in a heavily scattered environment where synchronizing the transmitters and developing channel statistics has proven difficult to achieve. Sensors measure a signal in noise, modulate the measured data over an OFDM subcarrier, and transmit this to a fusion center over a Gaussian multiple-access channel. The transmissions are received at the fusion center using an OFDM receiver, and the estimation process is completed. Simulations demonstrate the effectiveness of the technique.