6 research outputs found
Radar and Communication Coexistence Enabled by Interference Exploitation
In this paper, we propose a novel approach for the spectrum sharing between Multi-Input-Multi-Output (MIMO) radar and downlink multi-user Multi-Input- Single-Output (MU-MISO) communication system. To obtain a power-efficient beamforming at the base station (BS), we utilize the constructive multi- user interference (MUI) as a source of green signal power. The proposed beamforming design mainly focuses on two optimization problems, i.e., transmit power minimization for BS and interference minimization for radar, subject to given performance requirements of the two systems. We further consider the impact of the proposed methods on radar, where the detection probability for MIMO radar in the presence of the interference from BS is analytically derived, and important trade-offs are revealed. Numerical results show that the proposed approach outperforms the conventional beamforming designs by achieving a significant performance gain under the discussed coexistence scenario
Towards Dual-functional Radar-Communication Systems: Optimal Waveform Design
We focus on a dual-functional multi-input-multi-output (MIMO)
radar-communication (RadCom) system, where a single transmitter communicates
with downlink cellular users and detects radar targets simultaneously. Several
design criteria are considered for minimizing the downlink multi-user
interference. First, we consider both the omnidirectional and directional
beampattern design problems, where the closed-form globally optimal solutions
are obtained. Based on these waveforms, we further consider a weighted
optimization to enable a flexible trade-off between radar and communications
performance and introduce a low-complexity algorithm. The computational costs
of the above three designs are shown to be similar to the conventional
zero-forcing (ZF) precoding. Moreover, to address the more practical constant
modulus waveform design problem, we propose a branch-and-bound algorithm that
obtains a globally optimal solution and derive its worst-case complexity as a
function of the maximum iteration number. Finally, we assess the effectiveness
of the proposed waveform design approaches by numerical results.Comment: 13 pages, 10 figures. This work has been submitted to the IEEE for
possible publication. Copyright may be transferred without notice, after
which this version may no longer be accessibl
Joint Beamforming for RIS-Assisted Integrated Sensing and Communication Systems
Integrated sensing and communications (ISAC) is an emerging critical
technique for the next generation of communication systems. However, due to
multiple performance metrics used for communication and sensing, the limited
degrees-of-freedom (DoF) in optimizing ISAC systems poses a challenge.
Reconfigurable intelligent surfaces (RIS) can introduce new DoF for beamforming
in ISAC systems, thereby enhancing the performance of communication and sensing
simultaneously. In this paper, we propose two optimization techniques for
beamforming in RIS-assisted ISAC systems. The first technique is an alternating
optimization (AO) algorithm based on the semidefinite relaxation (SDR) method
and a one-dimension iterative (ODI) algorithm, which can maximize the radar
mutual information (MI) while imposing constraints on the communication rates.
The second technique is an AO algorithm based on the Riemannian gradient (RG)
method, which can maximize the weighted ISAC performance metrics. Simulation
results verify the effectiveness of the proposed schemes. The AO-SDR-ODI method
is shown to achieve better communication and sensing performance, than the
AO-RG method, at a higher complexity. It is also shown that the
mean-squared-error (MSE) of the estimates of the sensing parameters decreases
as the radar MI increases.Comment: 30 pages, 8 figures. This paper has been submitted to IEEE
Transactions on Communication