## 4 Implementation of Joint Plans
### Joint Signal Processing Flow  
The waveform design and processing method for radar jamming and communication integration based on UFMC chirp is depicted in Figure 5.  
At the transmitter, the communication data are first converted from serial to parallel and then undergo multicarrier mapping to generate transmitted data. These data, after QAM modulation, produce frequency-domain communication signals. Simultaneously, the baseband waveforms of jamming signals are generated based on intercepted radar signals. The communication signals and jamming signals are superimposed and transformed into time-domain digital signals through sub-band IDFT. Sub-band filters are employed to reduce the out-of-band leakage of each sub-band. The time-domain signals of each sub-band are then superimposed, and before entering the radio frequency domain, their average value is removed, and the power is normalized to ensure uniform power across all transmitted signals. Following wireless transmission, in the jamming scenario, these signals reach the receiving end. At the communication receiver, the received signal undergoes pulse synchronization first to determine the arrival time of the signal, ensuring accurate sampling. After amplification, it passes through a sub-band filter group to match the received signal and identify each sub-band. The signal undergoes zero-padding fast Fourier transform (FFT), followed by down-sampling to obtain the transmitted symbol information. Due to the impact of multiple paths in the channel, delays in the time domain are converted into phase differences in the frequency domain, affecting the demodulation results. Therefore, channel equalization is applied to the frequency signal to mitigate the influence of multipath channels. The jamming signal and communication signal are orthogonally demodulated and separated. Since the jamming signal is an LFM signal that does not carry communication data, it can be utilized for channel estimation, aiding in data recovery and assisting the communication system in restoring the original communication information. When considering the impact of multipath channels in communication processing, assuming the number of multipath channels is \(L\), the integrated signal received at the communication end is given by:  
\[\mathbf{y}(t)=\mathbf{h}\mathbf{s}(t)+\mathbf{z}(t) \tag{18}\]  
where \(\mathbf{z}(t)\) is the additive Gaussian white noise, \(\mathbf{h}\) is the Toeplitz channel matrix with its first column as \([h_{0}(t),h_{1}(t),\cdots,h_{L-1}(t),0,\cdots,0]^{T}\), and \(h_{l}(t)\) is the channel impulse response on the \(lth\) path, expressed as:  
\[h_{l}(t)=a_{l}\delta(t-\tau_{l}) \tag{19}\]  
Figure 5: Joint radar jamming and communication system flow based on UFMC chirp signal. where \(a_{l}\) is the attenuation coefficient of the \(lth\) path and \(\tau_{l}\) is the delay of the \(lth\) path. The frequency-domain signal obtained by the communication target after receiving the time-domain signal, going through a matched filter, and undergoing FFT operation, can be expressed as:  
\[\mathbf{Y}=\mathbf{HQ}\mathbf{X}+\mathbf{Z} \tag{20}\]  
where:  
\[\mathbf{Y}=\Big{[}\mathbf{Y}_{1}^{T},\mathbf{Y}_{2}^{T},\cdots,\mathbf{Y}_{N_ {R_{p}}}^{T}\Big{]}^{T}, \tag{21}\]  
\[\mathbf{Y}_{p}=\big{[}Y_{p}[0],Y_{p}[1],\cdots,Y_{p}[2c-1]\big{]}^{T}, \tag{22}\]  
\[\mathbf{H}=diag\big{\{}\mathbf{H}_{1},\mathbf{H}_{2},\cdots,\mathbf{H}_{N_{R_ {p}}}\big{\}}, \tag{23}\]  
\[\mathbf{H}_{p}=diag\big{\{}H_{p}[0],H_{p}[1],\cdots,H_{p}[2c-1]\big{\}}, \tag{24}\]  
\[\mathbf{X}=\Big{[}\mathbf{X}_{1}^{T},\mathbf{X}_{2}^{T},\cdots,\mathbf{X}_{N _{R_{p}}}^{T}\Big{]}^{T}, \tag{25}\]  
\[\mathbf{y}(t)=\mathbf{h}\mathbf{s}(t)+\mathbf{z}(t) \tag{18}\]0  
where \(\mathbf{Y}_{p}\) is the frequency-domain signal on the \(pth\) sub-band at the receiver and \(Y_{p}(k)\) is the information carried on the \(kth\) subcarrier in the \(pth\) sub-band.