On the Analytical Communication Performance of LPD QS-CDMA with Reduced Cyclostationary Characteristics

Low Probability of Detection (LPD) Communication is becoming increasingly important both in military tactical and civilian communication networks. The goal of LPD communication is to hide the overall existence of transmission in the presence of an adversary. Following recent work on LPD approaches that aim to safeguard against sophisticated adversaries that exploit the transmitted signals' periodic structure for improved detection, we study the implications of a non-strictly cooperating friendly receiver in the system's communication performance. In particular, we investigate the Bit-Error Rate (BER) performance of a Code Division Multiple Access (CDMA) based LPD communication system employing dithering and random sequence selection, when the friendly receiver holds no knowledge of the randomization patterns. This is particularly important for large scalable networks where key sharing presents large overhead and in particular when there may be a significant dynamic changes in the network composition and topology because of either mobility or devices joining/leaving. Further, it helps in situations when attackers may monitor network control channels for the randomization pattern (e.g. random number generator seed) distribution. We provide an analytical expression for the probability of error during symbol detection and compare with system simulations showing that they match perfectly!