A general jamming model of spread-spectrum systems

The author considers a general model of spread-spectrum systems with real random spreading codes in a jamming environment, and its asymptotic behavior in the case of arbitrary jamming waveforms. In addition to the general model of traditional coherent spread-spectrum systems, an ideal modified version is introduced and this model is analyzed from an information-theoretic viewpoint. The model adopted is that of a simple point-to-point communication system with fully synchronized transmitter and receiver in a simple channel with white Gaussian noise and arbitrary jamming signal. The model based on the vector signal space description is valid for all spread-spectrum techniques with real random spreading codes and coherent detection. The asymptotic behavior of these systems is examined with emphasis on the effect of the jammer. It is shown that in traditional systems the channel converges to a Gaussian noisy channel in the limit in the case of almost any jamming signal, while in the new ideal modified system the channel converges to a white Gaussian noisy channel in the limit in the case of any jamming signal when the processing gain goes to infinity. For this latter model the asymptotic capacity region is determined