Analysis of pseudo-random timing for lowobservable communication signals

It is often desirable to transmit a communication signal in such a way that information cannot be extracted from it by a non-cooperative receiver. Typically, this is accomplished via encryption, which codes the bits such that information cannot be extracted from them. In this paper, we consider an added layer of protection to make it difficult for a non- cooperative receiver to reliably extract bits from the received signal. This will be termed "low observable (LO) communications." Specifically, we investigate the use of a pseudorandom (PR) timing phase as a means of disrupting blind cyclostationarity-based equalization algorithms. We model the PR timing pattern as a doubly (time and frequency) selective channel. We show that if the PR timing pattern is known, channel identification can be performed, and otherwise it cannot be reliably performed. As opposed to spread-spectrum techniques, PR timing provides LO communications without consuming additional bandwidth.