Relaxed bandwidth sharing with space division multiplexing/spl trade/

The phases of adjacent frequencies in a wavepacket evolve along its electromagnetic path at rates proportional to their wavelengths, so that the spectral phase gradient is proportional to the distance /spl tau/ from the source. Scanning of this phase gradient at a controlled rate /spl beta/ at a receiver converts it to a frequency shift /spl delta//spl omega/ proportional to /spl omega//spl beta/r, enabling r to be determined without use of time or phase reference. This enables us to introduce source distance as the basic dimension, instead of carrier frequency and spread spectrum encoding, for separation of signals from multiple sources. The entire bandwidth above a minimum wavelength that depends on the spacing between transmitters can be used by each transmitter for dedicated communication with the given receiver. Preliminary results using DSP implementation, and limits of the technique are discussed.