Initial power adjustment and link adaptation from direct-sequence spread-spectrum demodulator statistics

Abstract

Statistics obtained during demodulation are used in a direct-sequence spread-spectrum packet radio network to govern the adjustment of transmitter power within the first few packets of a session. The statistics are also employed by an adaptive transmission protocol to select the modulation parameters and the rate of the error-control code for each packet. The power-adjustment protocol uses the statistics to ensure that the transmitter power level is high enough to satisfy the signal strength requirements at the receiver and low enough to prevent unnecessary interference to nearby radios. We describe a protocol for which modulation and coding parameters are adapted to achieve the most efficient combination for the given channel conditions. We evaluate the performance of each protocol for several channels. The protocols are not given any information about the type of channel or the channel parameters, yet they are able to use the demodulator statistics to efficiently set the initial power level and adapt transmissions throughout the session.