A SOFT-DECISION SCALINGMETRIC EMPLOYINGRECEIVER STATISTICS FOR DIRECT-SEQUENCESPREAD-SPECTRUMPACKET RADIO NETWORKS

Packet radios for tactical networks must be able to communicate over highly dynamic links that are susceptible to variations in propagation loss, jamming, and multiple-access interference. We describe and evaluate an adaptive scaling metric for soft-decision decoding in direct-sequence spread-spectrum receivers for tactical radio networks. The metric is derived from post-detection signal quality statistics that are developed in the demodulator, and it is applied to the demodulator's soft­ decision outputs before they are sent to the decoder. To maintain efficient use of assigned channel and spectrum resources, our metric exploits the nature of the spread-spectrum signal to obtain demodulator statistics during the reception of the desired transmission and therefore requires no pilot symbols or channel measurements. We compare the performance of our proposed adaptive scaling metric with a fixed soft-decision metric and with the log-likelihood ratio metric.