Abstract: The residue number system is a carry-free system and allows a high degree of concurrency. Due to this property, the RNS has received considerable attention in digital signal processing systems with intensive additions and multiplications. And these DSP modules are important for software definition radio systems. In this paper, we first introduce the fundamental concept of RNS and the recent research about it. Then we point out the key units of RNS-based DSP systems and present a DSP architecture based on RNS. Furthermore, combined with the properties of fault-tolerance and parallelism of RNS, we introduce a RNS-based parallel orthogonal signaling system. Finally, we indicate the applications of RNS in the array-based SDR and aeronautic signal processing platforms.