System and method for reuse of communication spectrum for fixed and mobile applications with efficient method to mitigate interference

摘要

A communications system network that enables secondary use of spectrum on a non-interference basis is disclosed. Each secondary transceiver measures the background spectrum. The system uses a modulation method to measure the background signals that eliminates self-generated interference and also identifies the secondary signal to all primary users via on/off amplitude modulation, allowing easy resolution of interference claims. The system uses high-processing gain probe waveforms that enable propagation measurements to be made with minimal interference to the primary users. The system measures background signals and identifies the types of nearby receivers and modifies the local frequency assignments to minimize interference caused by a secondary system due to non-linear mixing interference and interference caused by out-of-band transmitted signals (phase noise, harmonics, and spurs). The system infers a secondary node's elevation and mobility (thus, its probability to cause interference) by analysis of the amplitude of background signals. Elevated or mobile nodes are given more conservative frequency assignments that stationary nodes.

主权项

id="REI-00009" date="20141223" 1. A method for a network of secondary communication devices consisting of transceivers, base stations and a central controller sharing a radio frequency channel with existing primary users with minimal interference to the primary users comprising the steps of:
each secondary transceiver and secondary base station measuring the primary signal level in the channel, each secondary transceiver communicating the signal level to the central controller, and the central controller determining which channels each node may potentially use by comparing primary signal level to a threshold value, wherein a portion of the secondary transceivers and secondary base stations in a region distant from where the channel is being used sequentially transmit a short duration probe signal with a certain power level (P_probe), the secondary transceivers and secondary base stations within a primary region where the channel is being used measure the probe signal amplitude value (P_received) and send these values to the central controller, and the central controller determines the maximum power level for each secondary transceivers and secondary base stations in the distant region by the formula: P_transmission (dBm)=P_probe (dBm)−P_received (dBm)+constant, with the value of the constant depending on the maximum interference level allowed in the primary region plus a safety margin, and the above steps are repeated in regular intervals.