We are interested in a communication system that operates in the presence of an intelligent jammer, under stringent power constraints, but with flexible bandwidth constraints. We optimize some of the key elements in the transceiver design for low power consumption, and thus high complexity components of the system, such as matched filters (MF), forward error correction (FEC) that employs iterative decoders, coherent demodulators, and bandwidth-efficient modulation formats, are not feasible for this research. Rather, our system is designed using M -ary frequency shift keying (MFSK) with non-coherent detection and fast frequency hopping (FFH), optimized two-pole bandpass filters (BPF), and Reed-Solomon (RS) codes with hard-decision decoding. Among other things, we show that by properly optimizing the key parameters of the BPFs and RS codes, we can design the system to be significantly less complex than the MF system with a performance loss of less than 1.4 dB for most scenarios that we considered. Further, the 2-pole BPF system can actually outperform the corresponding MF system by up to 2.4 dB in the presence of multi-tone jamming.INDEX TERMS M -ary FSK, multipath fading, ultra-low power-consumption, non-coherent detection, low-complexity filtering, fast frequency-hopping, partial-band noise jamming, multi-tone jamming, Reed-Solomon codes.
In one of our previous papers, we designed an ultra-low power non-coherent MFSK system using 2-pole bandpass filters to replace matched filters for detection and showed the performance loss between our proposed system and the optimal MFSK system using matched filters for detection was no greater than 1.2 dB in all alphabet size, phase continuity and channel conditions we analyzed. In this paper, we improve our previous design by considering the power-bandwidth tradeoff, and we show that we can save a large percentage of system bandwidth by sacrificing a small amount of power, when the demodulator and coding parameters are optimized. For example, we can save 50% of system bandwidth at the cost of 1 dB loss in performance compared to our previous system design. We further extend the results to include Gaussian filtering, we quantify the performance loss as a function of both the system bandwidth saved and the time-bandwidth product of the Gaussian filter, and we compare the performance of the M -ary GFSK system with the corresponding MFSK system.INDEX TERMS M -ary FSK, M -ary GFSK, multipath fading, ultra-low power-consumption, non-coherent detection, low-complexity filtering, Reed-Solomon codes.
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