41 research outputs found
Coexistence of MIMO Radar and FD MIMO Cellular Systems with QoS Considerations
In this work, the feasibility of spectrum sharing between a multiple-input
multiple-output (MIMO) radar system (RS) and a MIMO cellular system (CS),
comprising of a full duplex (FD) base station (BS) serving multiple downlink
and uplink users at the same time and frequency is investigated. While a joint
transceiver design technique at the CS's BS and users is proposed to maximise
the probability of detection (PoD) of the MIMO RS, subject to constraints of
quality of service (QoS) of users and transmit power at the CS, null-space
based waveform projection is used to mitigate the interference from RS towards
CS. In particular, the proposed technique optimises the performance of PoD of
RS by maximising its lower bound, which is obtained by exploiting the
monotonically increasing relationship of PoD and its non-centrality parameter.
Numerical results show the utility of the proposed spectrum sharing framework,
but with certain trade-offs in performance corresponding to RS's transmit
power, RS's PoD, CS's residual self interference power at the FD BS and QoS of
users
Joint Transceiver Design for Dual-Functional Full-Duplex Relay Aided Radar-Communication Systems
Driven by the demand for massive and accurate sensing data to achieve wireless network intelligence under a limited available spectrum, the coexistence between radar and communication systems has attracted public attention. In this paper, we investigate a novel dual-functional full-duplex relay aided radar-communication system where the phased-array radar is employed at the amplify-and-forward (AF) relay. A joint transceiver design is proposed to maximize the minimum signal-to-interference-plus-noise ratio (SINR) among all detection directions at the radar receiver under communication quality-of-service and total energy constraints. The formulated optimization problem is particularly challenging due to the highly nonconvex objective function and constraints. Based on the problem structure, we equivalently decompose it into the radar-energy and relay-energy minimization problems under SINR requirements. To solve the radar-energy minimization problem, we propose a low-complexity algorithm based on the alternating direction method of multipliers to optimize the radar transmit power and receiver. The relay-energy minimization problem can be simplified into an equivalent quadratic programming problem by introducing an insightful unitary matrix. Then, the closed-form expression for the AF relay beamforming matrix can be derived, which is jointly determined by the channel condition of relay communication and the detection direction of the radar. After that, we introduce the overall transceiver design algorithm to the original problem and discuss its optimality and computational complexity. Simulation results verify that the proposed algorithm significantly outperforms other benchmark algorithms
Co-Designing Statistical MIMO Radar and In-band Full-Duplex Multi-User MIMO Communications
We consider a spectral sharing problem in which a statistical (or widely
distributed) multiple-input-multiple-output (MIMO) radar and an in-band
full-duplex (IBFD) multi-user MIMO (MU-MIMO) communications system concurrently
operate within the same frequency band. Prior works on joint
MIMO-radar-MIMO-communications (MRMC) systems largely focus on either colocated
MIMO radars, half-duplex MIMO communications, single-user scenarios, omit
practical constraints, or MRMC co-existence that employs separate
transmit/receive units. In this paper, we present a co-design framework that
addresses all of these issues. In particular, we jointly design the statistical
MIMO radar codes, uplink (UL)/downlink (DL) precoders of in-band full-duplex
multi-user MIMO communications, and corresponding receive filters using our
proposed metric of compounded-and-weighted sum mutual information. This
formulation includes practical constraints of UL/DL transmit powers, UL/DL
quality-of-service, and peak-to-average-power ratio. We solve the resulting
highly non-convex problem through a combination of block coordinate descent and
alternating projection methods. Extensive numerical experiments show that our
methods achieve monotonic convergence in a few iterations, improve radar target
detection over conventional codes, and yield a higher achievable data rate than
standard precoders.Comment: 20 pages, 8 figures, 1 tabl
Rate-splitting multiple access for non-terrestrial communication and sensing networks
Rate-splitting multiple access (RSMA) has emerged as a powerful and flexible
non-orthogonal transmission, multiple access (MA) and interference management
scheme for future wireless networks. This thesis is concerned with the application of
RSMA to non-terrestrial communication and sensing networks. Various scenarios
and algorithms are presented and evaluated.
First, we investigate a novel multigroup/multibeam multicast beamforming strategy
based on RSMA in both terrestrial multigroup multicast and multibeam satellite
systems with imperfect channel state information at the transmitter (CSIT). The
max-min fairness (MMF)-degree of freedom (DoF) of RSMA is derived and shown
to provide gains compared with the conventional strategy. The MMF beamforming
optimization problem is formulated and solved using the weighted minimum mean
square error (WMMSE) algorithm. Physical layer design and link-level simulations
are also investigated. RSMA is demonstrated to be very promising for multigroup
multicast and multibeam satellite systems taking into account CSIT uncertainty
and practical challenges in multibeam satellite systems.
Next, we extend the scope of research from multibeam satellite systems to satellite-
terrestrial integrated networks (STINs). Two RSMA-based STIN schemes are
investigated, namely the coordinated scheme relying on CSI sharing and the co-
operative scheme relying on CSI and data sharing. Joint beamforming algorithms
are proposed based on the successive convex approximation (SCA) approach to
optimize the beamforming to achieve MMF amongst all users. The effectiveness and
robustness of the proposed RSMA schemes for STINs are demonstrated.
Finally, we consider RSMA for a multi-antenna integrated sensing and communications (ISAC) system, which simultaneously serves multiple communication users
and estimates the parameters of a moving target. Simulation results demonstrate
that RSMA is beneficial to both terrestrial and multibeam satellite ISAC systems by
evaluating the trade-off between communication MMF rate and sensing Cramer-Rao
bound (CRB).Open Acces
A Tutorial on Interference Exploitation via Symbol-Level Precoding: Overview, State-of-the-Art and Future Directions
IEEE Interference is traditionally viewed as a performance limiting factor in wireless communication systems, which is to be minimized or mitigated. Nevertheless, a recent line of work has shown that by manipulating the interfering signals such that they add up constructively at the receiver side, known interference can be made beneficial and further improve the system performance in a variety of wireless scenarios, achieved by symbol-level precoding (SLP). This paper aims to provide a tutorial on interference exploitation techniques from the perspective of precoding design in a multi-antenna wireless communication system, by beginning with the classification of constructive interference (CI) and destructive interference (DI). The definition for CI is presented and the corresponding mathematical characterization is formulated for popular modulation types, based on which optimization-based precoding techniques are discussed. In addition, the extension of CI precoding to other application scenarios as well as for hardware efficiency is also described. Proof-of-concept testbeds are demonstrated for the potential practical implementation of CI precoding, and finally a list of open problems and practical challenges are presented to inspire and motivate further research directions in this area
Information Theoretic Approach for Waveform Design in Coexisting MIMO Radar and MIMO Communications
We investigate waveform design for coexistence between a multipleinput
multiple-output (MIMO) radar and MIMO communications
(MRMC), with a radar-centric criterion that leads to a minimal
interference in the communications system. The communications
use the traditional mode of operation in Long Term Evolution
(LTE)/Advanced (FDD), where we formulate the design problem
based on information-theoretic criterion with the discrete phase
constraint at the design stage. The optimization problem, is nonconvex,
multi-objective and multi-variable, where we propose an
efficient algorithm based on the coordinate descent (CD) framework
to simultaneously improve radar target detection performance and
the communications rate. The numerical results indicate the effectiveness
of the proposed algorithm in designing discrete phase set of
sequences, potentially binary
Interference Exploitation via Symbol-Level Precoding: Overview, State-of-the-Art and Future Directions
Interference is traditionally viewed as a performance limiting factor in wireless communication systems, which is to be minimized or mitigated. Nevertheless, a recent line of work has shown that by manipulating the interfering signals such that they add up constructively at the receiver side, known interference can be made beneficial and further improve the system performance in a variety of wireless scenarios, achieved by symbol-level precoding (SLP). This paper aims to provide a tutorial on interference exploitation techniques from the perspective of precoding design in a multi-antenna wireless communication system, by beginning with the classification of constructive interference (CI) and destructive interference (DI). The definition for CI is presented and the corresponding mathematical characterization is formulated for popular modulation types, based on which optimization-based precoding techniques are discussed. In addition, the extension of CI precoding to other application scenarios as well as for hardware efficiency is also described. Proof-of-concept testbeds are demonstrated for the potential practical implementation of CI precoding, and finally a list of open problems and practical challenges are presented to inspire and motivate further research directions in this area