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We consider a multiple-input multiple-output (MIMO) dual function radar communication (DFRC) system employing frequency hopping (FH) radar waveforms. The DFRC system embeds communication symbols using code-shift keying (CSK) strategy. Each symbol is represented by a phase modulated pulse code sequence which multiplies the radar hops in fast-time before transmitted from the MIMO radar platform. This strategy allows for reduced clutter modulation caused by changed radar waveforms within coherent processing interval (CPI). We analyze the effect of this communication symbol embedding scheme on range sildelobe levels (RSLs) and derive the DFRC probability of target detection. We show that the DFRC waveforms enhances target visibility leading to improved target detection compared with the FH radar without signal embedding.

We consider a code-shift keying (CSK) dual-function radar-communication (DFRC) system where the radar implements frequency hopping wideband signal that is modulated by the communication symbols. Each symbol is represented by a phase coded waveform with derivative phase shift keying (DPSK) modulation. The information sequences are multiplied with the FH waveforms in fast-time and are transmitted through the multiple-input multiple-output (MIMO) radar platforms. We use the genetic algorithm (GA) to design the optimum CSK sequences to reduce the radar range sidelobes modulation (RSM) which is imperative for clutter mitigation. It is shown that the optimal CSK sequences yield a substantial reduction in the range sidelobe level (RSL) fluctuations by simultaneously reducing the DFRC system's RSLs. Additionally, the proposed DFRC system with the optimized waveform design provides good spectrum containment and achieves high communication data rates by enabling the repeated use of hopping code values in the FH code design.

In this paper, we compare the performance of different phase modulated frequency hopping (FH) multiple-input multiple-output (MIMO) radar waveforms. The communication symbols are embedded into the FH waveforms under the auspices of dual-function (DF) radar and communications system. In the proposed scheme, each embedded symbol is represented by a sequence of phases. The phase modulated sequence is embedded through multiplication with the radar hops and is transmitted through a MIMO radar platform. Using this scheme, we consider information embedding in MIMO FH radar implementing different types of phase modulated sequence, including phase shift keying (PSK), differential phase shift keying (DPSK) and continuous phase modulation (CPM). We analyze the corresponding ambiguity functions (AFs) in terms of reducing or increasing range and Doppler sidelobes compared to the FH radar without any signal embedding. The spectral sidelobe levels and the complexity of the demodulator at the communication receiver are also examined. It is shown the proposed embedding scheme for DPSK and CPM minimizes the frequency leakage outside the radar signal bandwidth. To demonstrate the effectiveness of proposed scheme, we compare its performance with existing embedding schemes, all for FH radars. It is shown that our approach, in its significant reductions of range sidelobes, permits high data rate transmission. This is made possible because the FH radar can now afford using duplicate hopping code values without the penalty of incurring high correlations, or range sidelobe levels.

We present a dual-function radar communication (DFRC) system applying signal embedding through a code shift keying (CSK) strategy. The information symbol is phase encoded into a sequence and then modulated by the continuous phase modulation (CPM) before embedding into frequency hopping (FH) radar sub-pulses. The CPM modulated communication symbol phase coded sequence is multiplied with the FH radar waveforms in fast-time and transmitted through multiple-input multiple-output (MIMO) radar platforms. We address the problem of range sidelobe modulation (RSM) and propose the design of the optimum CSK sequences to reduce the degree of change in the range sidelobe levels (RSLs) of the ambiguity function (AF). It is shown that the optimum CSK sequences yield significant reduction in the RSLs of the DFRC system. They also maintain the same degree of correlation between FH sub-pulses regardless of the communication symbol sequences embedded. Additionally, the proposed DFRC system with the optimized waveform design provides good spectrum containment and achieves high communication data rates.

In this paper, we propose a method for information embedding into the emission of frequency hopping (FH) multiple-input multiple-output (MIMO) radar. The differential phase shift keying (DPSK) modulated communication symbols are embedded into each pulse of the FH radar waveforms. We examine the effect of DPSK symbol embedding on the radar operation by analyzing the range sidelobes performance, power spectral density (PSD) and data rate of the system. The proposed system shows significant reduction in range sidelobes, good spectral containment and achieves high communication data rates. The latter is enabled by synthesizing a large number of orthogonal waveforms.

We present a dual-function radar communication (DFRC) system in which phase modulated information symbols are embedded in the multiple-input multiple-output (MIMO) frequency hopping (FH) radar sub-pulses in fast-time. The communications are considered as the secondary function of the proposed dual-function radar communication (DFRC) systems. We use differential phase shift keying (DPSK) and continuous phase modulation (CPM). These modulations preserve the continuous phase between the FH sub-pulses, unlike phase shift keying (PSK) modulated symbols. The performance of FH/DPSK and FH/CPM systems is compared with that of the FH/PSK system in terms of range sidelobe levels (RSL) and power spectral density (PSD). It is shown that the proposed DFRC systems exhibit better spectral containment and lower spectral sidelobe levels. The communication data rates for the proposed system are derived, and to assume relatively high values.

Information embedding into the emission of multiple-input multiple-output (MIMO) frequency hopping (FH) radar is analyzed. It is assumed that the radar is primary under dual function radar communication system platforms. phase shift keying (PSK) communication symbols are embedded in each hop of the FH waveforms. The impact of embedding is a significant reduction in range sidelobe levels. We examine the impact of PSK symbol embedding on the power spectral density (PSD) of the MIMO radar. It is shown that there is spectral leakage due to the disruption of the continuous phase of the FH waveforms by the PSK symbol embedding. The trade-off between low sidelobe levels and low spectral leakage is analyzed. To maintain the phase continuity between the frequency hops, modulation of FH waveforms with frequency shift keying (FSK) symbols is considered and its performance is compared with that of the FH/PSK radar communication waveforms.

There is a presumed adverse effect on radar operation brought about from embedding communication signals in radar waveforms. Contrary to that presumption, we show in this paper that modulation of the radar pulse can indeed benefit both radar and communications in the dual system paradigm. This is shown by analyzing the impact of phase-shift keying (PSK) symbol embedding on the ambiguity function (AF) of a multiple-input multiple-output (MIMO) radar. Our analysis shows that the embedded PSK symbols yield reduction in the AF sidelobe peaks for a single pulse as well as for a series of radar pulses. To prove these results, we analyze the AF with and without the PSK symbol embedding. It is shown that the embedding of PSK symbols enable increasing the number of orthogonal transmit waveforms that can be used without increasing the sidelobe levels (SLL) of the corresponding AF.