Joint radar-communication waveform designs using signals from multiplexed users

Joint radar-communication designs are exploited in applications where radar and communications systems share the same frequency band or when both radar sensing and information communication functions are required in the same system. Finding a waveform that is suitable for both radar and communication is challenging due to the difference between radar and communication operations. In this paper, we propose a new method of designing dual-functional waveforms for both radar and communication using signals from multiplexed communications users. Specifically, signals from different communications users multiplexed in the time, code or frequency domains across different data bits are linearly combined to generate an overall radar waveform. Three typical radar waveforms are considered. The coefficients of the linear combination are optimized to minimize the mean squared error with or without a constraint on the signal-to-noise ratio (SNR) for the communications signals. Numerical results show that the optimization without SNR constraint can almost perfectly approximate the radar waveform in all the cases considered, giving good dual-functional waveforms for both radar and communication. Also, among different multiplexing techniques, time division multiple access is the best option to approximate the radar waveform, followed by code division multiple access and orthogonal frequency division multiple access

Integrated Sensing and Communications: Recent Advances and Ten Open Challenges

It is anticipated that integrated sensing and communications (ISAC) would be one of the key enablers of next-generation wireless networks (such as beyond 5G (B5G) and 6G) for supporting a variety of emerging applications. In this paper, we provide a comprehensive review of the recent advances in ISAC systems, with a particular focus on their foundations, system design, networking aspects and ISAC applications. Furthermore, we discuss the corresponding open questions of the above that emerged in each issue. Hence, we commence with the information theory of sensing and communications (S$\&$C), followed by the information-theoretic limits of ISAC systems by shedding light on the fundamental performance metrics. Next, we discuss their clock synchronization and phase offset problems, the associated Pareto-optimal signaling strategies, as well as the associated super-resolution ISAC system design. Moreover, we envision that ISAC ushers in a paradigm shift for the future cellular networks relying on network sensing, transforming the classic cellular architecture, cross-layer resource management methods, and transmission protocols. In ISAC applications, we further highlight the security and privacy issues of wireless sensing. Finally, we close by studying the recent advances in a representative ISAC use case, namely the multi-object multi-task (MOMT) recognition problem using wireless signals.Comment: 26 pages, 22 figures, resubmitted to IEEE Journal. Appreciation for the outstanding contributions of coauthors in the paper

Co-designed radar-communication using linear frequency modulation waveform

The expansion of consumer and wireless devices has placed increasing demand on signal bandwidth. This increased demand on a finite resource is in turn driving interest in more efficient ways to use available bandwidth. One approach is through mixed modulation of existing waveforms to achieve complementary objectives. Historically, mixed modulated signals have been designed to include some degree of orthogonality between the different waveforms to preclude interference. Such approaches usually involve use of time division multiple access (TDMA) or code division multiple access (CDMA), or the use of orthogonal frequency division multiplexing. With the evolution of digital signal processing, another approach is mixed modulation through intended modulation on pulse (IMOP). In the past, IMOP was challenging due to both the obvious cross interference concerns and the limits of signal processing technology [1]. However, advances in both digital electronics and signal processing have opened the door to re-exploring IMOP approaches

Co-designed radar-communication using linear frequency modulation waveform

As electromagnetic spectrum availability shrinks, there is growing interest in combining multiple functions, such as radar and communications signals, into a single multipurpose waveform. Historically mixed-modulation has used orthogonal separation of different message signals in different dimensions such as time or frequency. This research explores an alternative approach of implementing an in-band, mixed-modulated waveform that combines surveillance radar and communication functions into a single signal. The contribution of this research is the use of reduced phase-angle binary phase shift keying (BPSK) along with overlapped (channelized) spread-spectrum phase discretes based on pseudorandom noise sequences to encode multiple messages in a single pulse. The resulting mixed-modualted signal provides a low data rate communications message while minimizing the effect on radar performance. For the purpose of this research, radar performance will be evaluated in terms of power spectral density, matched filter auto-correlation for target detection, and the ambiguity function

Co-designed radar-communication using linear frequency modulation waveform

The expansion of consumer and wireless devices has placed increasing demand on signal bandwidth. This increased demand on a finite resource is in turn driving interest in more efficient ways to use available bandwidth. One approach is through mixed modulation of existing waveforms to achieve complementary objectives. Historically, mixed modulated signals have been designed to include some degree of orthogonality between the different waveforms to preclude interference. Such approaches usually involve use of time division multiple access (TDMA) or code division multiple access (CDMA), or the use of orthogonal frequency division multiplexing. With the evolution of digital signal processing, another approach is mixed modulation through intended modulation on pulse (IMOP). In the past, IMOP was challenging due to both the obvious cross interference concerns and the limits of signal processing technology [1]. However, advances in both digital electronics and signal processing have opened the door to re-exploring IMOP approaches

Co-designed radar-communication using linear frequency modulation waveform

As electromagnetic spectrum availability shrinks, there is growing interest in combining multiple functions, such as radar and communications signals, into a single multipurpose waveform. Historically mixed-modulation has used orthogonal separation of different message signals in different dimensions such as time or frequency. This research explores an alternative approach of implementing an in-band, mixed-modulated waveform that combines surveillance radar and communication functions into a single signal. The contribution of this research is the use of reduced phase-angle binary phase shift keying (BPSK) along with overlapped (channelized) spread-spectrum phase discretes based on pseudorandom noise sequences to encode multiple messages in a single pulse. The resulting mixed-modualted signal provides a low data rate communications message while minimizing the effect on radar performance. For the purpose of this research, radar performance will be evaluated in terms of power spectral density, matched filter auto-correlation for target detection, and the ambiguity function