Space-time coded collision-free frequency hopping in hostile jamming

This paper considers spectrally efficient and robust wireless system design under malicious jamming as well as unintentional interference. Due to limited spectrum and lack of a protected physical boundary, wireless systems are facing much more serious challenges in capacity and security than wired networks. When transmitted through the airlink, wireless signals are vulnerable to hostile jamming and interception. Frequency hopping (FH) system, which is robust under hostile jamming, was originally developed for secure communications in military applications. However, the efficiency of the conventional FH scheme is very low due to inappropriate use of the total available bandwidth and transmission collisions. To improve the system capacity, we develop a space-time coded collision-free frequency hopping (STC-CFFH) system based on the OFDM framework. Performance analysis of the proposed scheme is presented under frequency selective fading and partial band jamming through both theoretical analysis and simulation examples. Our analysis indicates that the STC-CFFH scheme improves the spectral efficiency and inherent anti-jamming features of conventional FH systems. Potentially, the proposed spectrally efficient anti-jamming scheme can be applied directly to military communications under hostile environments.