Intelligent Antijamming Communication Systems: Design of Pulses and Machine Learning Receiver

Abstract

The fth generation (5G) wireless technology is becoming more available and expected to play a key role in the fourth industrial revolution. For both commercial and covert communications, 5G is not just a simple advancement of 4G in capacity, but aims to support new services and roles with new business models and use cases, such as internet-of-things, critical mission control, unmanned military systems, and satellites. Since many unidentied systems are coping with others in common medium, antijamming (AJ) is of paramount importance for both commercial and covert communications to protect our signals form adversary. The AJ is an area of spectrum management to reduce or eliminate the eect of undesired jamming or interference signals. Against complex and fancy threats such as hybrid and intelligent jamming scenarios, intelligent AJ communication systems with autonomous, adaptive, and cognitive capabilities are highly desired. The intelligent AJ communication systems have been widely researched and developed over the perspective from the transmitter side to the receiver side and the entire system. The spread spectrum (SS) techniques, spreading the bandwidth of a signal beyond that actually required, have been developed not only for commercial communication but also for covert communication. Systems adopting SS techniques have been eectively utilized for the multiple access capability, suppression of interference, alleviation of multipath fading eects, and resilience against jamming signals [1]. In particular, among the three classes direct sequence (DS), frequency-hopping (FH), and time-hopping (TH) of SS systems, the TH SS systems, modulating the transmis- sion signal by shifting it arbitrarily in time, have been widely used due to their better (compared to the DS and FH SS systems) capability of resolving multipath, easiness in implementation with low complexity, and low probability of interception. On the other hand, code division multiple access (CDMA) provides multiple access capability and helps increasing system throughput by applying the SS notion. The DS-CDMA has been mostly studied in the literature and widely applicable in reality due to its low complexity and implementation cost. The performance of DS-CDMA is limited by jamming signals and interferences since they often exceed the anti-jamming capability of SS techniques.