Patent ID: 7146176

Claim:
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 the 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 at regular intervals.