# Chaos Based Frequency Modulation for Joint Monostatic and Bistatic Radar-Communication Systems
## 7 Conclusions  
In this work, we presented a waveform design for joint monostatic radar-communication and bistatic radar-communication systems. The generation of such a waveform is possible using a chaotic oscillator modeled as nonlinear differential equations. The digital information is embedded onto the chaotic oscillator using chaos shift keying. The resultant output of the oscillator is used as an instantaneous frequency to generate a chaos-based frequency-modulated waveform. This CBFM waveform is used for the dual application of radar detection and communications. We presented a nonlinear detection scheme to decode the digital information. Here, we used two synchronized chaotic oscillators to compare the error difference to determine the encoded bit. Through simulations, we showed that the bit error rate of the CBFM waveform closely matches the bipolar shift keying. The same nonlinear detection scheme is used at the bistatic radar receiver to synchronize it with the transmitter. We use the synchronized local response oscillator to reconstruct the transmitted FM waveform, which acts as the response for the matched filter. The cross-ambiguity functions revealed a sharp mainlobe peak with minimum sidelobes on the range-velocity planes desirable for high-resolution radar imaging. Signature analysis of the complex target revealed the high-resolution capability of the proposed waveform. However, due to the noise sensitivity of the nonlinear detector, our proposed approach is susceptible to a significant amount of noise levels. The self-ambiguity surface of CBFM waveforms for monostatic radars is of high quality. The sidelobes on the range-velocity planes are extremely low. The signature analysis illustrates that all the point reflectors could be distinguished accurately. In contrast to the bistatic configuration, the monostatic radar performed excellently for SNRs as low as \(-30\) dB. Our proposed work can have potential in airplanes, emergency response vehicles, and defense sectors where faster communication rates and accurate target detection are necessary. With the proposed work, both of these are achievable in addition to secure communications and high-resolution imagery. Conceptualization, C.S.P. ; methodology, C.S.P., A.N.B. and B.C. * (5) [PERSON]; [PERSON]; [PERSON] Optimum co-design for spectrum sharing between matrix completion based MIMO radars and a MIMO communication system. _IEEE Trans. Signal Process._**2016**, _64_, 4562-4575. [CrossRef]
* (6) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Joint system design for coexistence of MIMO radar and MIMO communication. _IEEE Trans. Signal Process._**2018**, _66_, 3504-3519. [CrossRef]
* (7) [PERSON]; [PERSON] Joint transmit designs for coexistence of MIMO wireless communications and sparse sensing radars in clutter. _IEEE Trans. Aerosp. Electron. Syst._**2017**, _53_, 2846-2864. [CrossRef]
* (8) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Joint radar and communication design: Applications, state-of-the-art, and the road ahead. _IEEE Trans. Commun._**2020**, _68_, 3834-3862. [CrossRef]
* (9) [PERSON]; [PERSON] Interference Mitigation Processing for Spectrum-Sharing Between Radar and Wireless Communications Systems. _IEEE Trans. Aerosp. Electron. Syst._**2013**, _49_, 1911-1919. [CrossRef]
* (10) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Interference Mitigation Methods for Coexistence of Radar and Communication. In Proceedings of the 15 th European Conference on Antennas and Propagation (EuCAP), Dusseldorf, Germany, 22-26 March 2021; pp. 1-4. * (11) [PERSON]; [PERSON] Joint wireless communication and radar sensing systems-state of the art and future prospects. _IET Microwaves, Antennas Propag._**2013**, \(7\), 876-885. [CrossRef]
* (12) [PERSON]; [PERSON]; [PERSON] Intrupulse Radar-Embedded Communications. _IEEE Trans. Aerosp. Electron. Syst._**2010**, _46_, 1185-1200. [CrossRef]
* (13) [PERSON]; [PERSON]; [PERSON]; [PERSON] Radar waveform design in spectrum sharing environment: Coexistence and cognition.