Rotatable antenna (RA) provides additional spatial degrees of freedom (DoFs) for communication systems by enabling per-antenna dynamic boresight adjustment, which is attractive for fairness-oriented multicast transmission. This letter investigates an RA-enhanced downlink multi-group multicast system. Specifically, we aim to maximize the minimum signal-to-interference-plus-noise ratio (SINR) among all users by jointly optimizing the multicast beamforming vectors and the RA boresight directions under transmit power and rotation constraints. To solve this non-convex problem, we first reformulate the max-min SINR objective via quadratic transform. Then, we develop an alternating optimization (AO) algorithm that iteratively updates the multicast beamforming and RA boresight directions. The beamforming vectors are obtained from a convex subproblem, while the boresight directions are refined using a successive convex approximation (SCA) procedure. Simulation results verify that the proposed RA-based scheme substantially enhances the fairness performance compared with fixed antenna-based and random-orientation benchmarks.
Rotatable Antenna-Enhanced Cell-Free Communication
South China University of Technology（华南理工大学）；KTH Royal Institute of Technology（皇家理工学院）；Friedrich Alexander-University Erlangen-Nürnberg（埃尔朗根-纽伦堡弗里德里希·亚历山大大学）
Antenna Orientation Optimization for Rotatable Antenna-Enabled ISAC Systems
School of Microelectronics, South China University of Technology（华南理工大学微电子学院）；School of Information Engineering, Guangdong University of Technology（广东工业大学信息工程学院）
Central China Normal University（华中师范大学）；Hubei University of Arts and Science（湖北文理学院）；Henan Polytechnic University（河南理工大学）；Laval University（拉瓦尔大学）；Memorial University（纪念大学）
Rotatable Antenna-Enabled Satellite Communication: Joint Design of Boresight Alignment and Beam Tracking
School of Microelectronics, South China University of Technology（华南理工大学微电子学院）；Department of Electronic and Electrical Engineering, Southern University of Science and Technology（南方科技大学电子电气工程系）；Shenzhen Key Laboratory of Optoelectronics and Intelligent Sensing（深圳光电子与智能传感重点实验室）；Wireless and Computing Research Institute, ZTE Corporation（中兴通讯无线与计算研究院）
Joint Transceiver Orientation Optimization for Rotatable-Antenna MIMO Capacity Maximization
School of Information Science and Electronic Engineering, Shanghai Jiao Tong University（上海交通大学信息科学与电子工程学院）；State Key Laboratory of Internet of Things for Smart City and the Department of Electrical and Computer Engineering, University of Macau（澳门大学物联网智能城市国家重点实验室及电气与计算机工程系）
South China University of Technology（华南理工大学）；University of Electronic Science and Technology of China（电子科技大学）；Southern University of Science and Technology（南方科技大学）；Shanghai Jiao Tong University（上海交通大学）
Joint Antenna Geometry and Transmit Covariance Design for Near-Field Multicast ISAC with Pinching Antenna Arrays
Hunan Institute of Science and Technology（湖南理工学院）；Hunan Institute of Engineering（湖南工程学院）；Donghua University（东华大学）；Laval University（拉瓦尔大学）；University of Saskatchewan（萨斯喀彻温大学）；Henan Polytechnic University（河南理工大学）
In a superimposed unicast and multicast transmission system, one layer of Successive Interference Cancellation (SIC) is required at each receiver to remove the multicast stream before decoding the unicast stream. In this paper, we show that a linearly-precoded Rate-Splitting (RS) strategy at the transmitter can efficiently exploit this existing SIC receiver architecture. By splitting the unicast message into common and private parts and encoding the common parts along with the multicast message into a super-common stream decoded by all users, the SIC is used for the dual purpose of separating …
In a Non-Orthogonal Unicast and Multicast (NOUM) transmission system, a multicast stream intended to all the receivers is superimposed in the power domain on the unicast streams. One layer of Successive Interference Cancellation (SIC) is required at each receiver to remove the multicast stream before decoding its intended unicast stream. In this paper, we first show that a linearly-precoded 1-layer Rate-Splitting (RS) strategy at the transmitter can efficiently exploit this existing SIC receiver architecture. We further propose multi-layer transmission strategies based on the generalized RS an…
The reconfigurable intelligent surface (RIS), which consists of a large number of passive and low-cost reflecting elements, has been recognized as a revolutionary technology to enhance the performance of future wireless networks. This paper considers an RIS assisted multicast transmission, where a base station (BS) with multiple-antenna multicasts common message to multiple single-antenna mobile users (MUs) under the assistance of an RIS. An equivalent channel model for the considered multicast transmission is analyzed, and then an optimization problem for the corresponding channel capacity is…
This paper studies the energy efficiency and sum rate trade-off for coordinated beamforming in multi-cell multi-user multigroup multicast multiple-input single-output systems. We first consider a conventional network energy efficiency maximization (EEmax) problem by jointly optimizing the transmit beamformers and antennas selected to be used in transmission. We also account for per-antenna maximum power constraints to avoid non-linear distortion in power amplifiers and user-specific minimum rate constraints to guarantee certain service levels and fairness. To be energy-efficient, transmit ante…
This paper considers the (NP-)hard problem of joint multicast beamforming and antenna selection. Prior work has focused on using Semi-Definite relaxation (SDR) techniques in an attempt to obtain a high quality sub-optimal solution. However, SDR suffers from the drawback of having high computational complexity, as SDR lifts the problem to higher dimensional space, effectively squaring the number of variables. This paper proposes a high performance, low complexity Successive Convex Approximation (SCA) algorithm for max-min SNR "fair" joint multicast beamforming and antenna selection under a sum …
Rotatable Antenna-Empowered Wireless Networks: A Tutorial
School of Microelectronics, South China University of Technology（华南理工大学微电子学院）；Department of Electronic and Electrical Engineering, Southern University of Science and Technology (SUSTech)（南方科技大学电子与电气工程系）；Department of Electrical and Computer Engineering, University of Waterloo（滑铁卢大学电气与计算机工程系）；State Key Laboratory of CNS/ATM and the School of Interdisciplinary Science, Beijing Institute of Technology（北京理工大学神经系统/原子交通控制国家重点实验室及交叉科学研究院）；National Key Laboratory of Wireless Communications, University of Electronic Science and Technology of China（电子科技大学无线通信国家重点实验室）；Department of Electronic Engineering, Shanghai Jiao Tong University（上海交通大学电子工程系）；School of Electronic and Information Engineering, South China University of Technology（华南理工大学电子与信息工程学院）
This paper considers the multi-group multicast beamforming optimization problem, for which the optimal solution has been unknown due to the non-convex and NP-hard nature of the problem. By utilizing the successive convex approximation numerical method and Lagrangian duality, we obtain the optimal multicast beamforming solution structure for both the quality-of-service (QoS) problem and the max-min fair (MMF) problem. The optimal structure brings valuable insights into multicast beamforming: We show that the notion of uplink-downlink duality can be generalized to the multicast beamforming probl…
This paper studies the multi-antenna multicast channel with integrated sensing and communication (ISAC), in which a multi-antenna base station (BS) sends common messages to a set of single-antenna communication users (CUs) and simultaneously estimates the parameters of an extended target via radar sensing. We investigate the fundamental performance limits of this ISAC system, in terms of the achievable rate for communication and the estimation Cramér-Rao bound (CRB) for sensing. First, we derive the optimal transmit covariance in semi-closed form to balance the CRB-rate (C-R) tradeoff, and acc…
A multi-antenna broadcast channel scenario is considered where a base station delivers contents to cache-enabled user terminals. A joint design of coded caching (CC) and multigroup multicast beamforming is proposed to benefit from spatial multiplexing gain, improved interference management and the global CC gain, simultaneously. The developed general content delivery strategies utilize the multiantenna multicasting opportunities provided by the CC technique while optimally balancing the detrimental impact of both noise and inter-stream interference from coded messages transmitted in parallel. …
Intelligent reflecting surfaces (IRSs) have received much attention recently and are envisioned to promote 6G communication networks. In this paper, for wireless communications aided by IRS units, we formulate optimization problems for power control under quality of service (QoS) and max-min fair QoS under three kinds of traffic patterns from a base station (BS) to mobile users (MUs): unicast, broadcast, and multicast. The optimizations are achieved by jointly designing the transmit beamforming of the BS and the phase shift matrix of the IRS. For power control under QoS, existing IRS studies i…
