Polar-Cap Codebook Design for MISO Rician Fading Channels with Limited Feedback

Reconfigurable Intelligent Surface-Aided MISO Systems with Statistical CSI: Channel Estimation, Analysis and Optimization

This paper investigates the reconfigurable reflecting surface (RIS)-aided multiple-input-single-output (MISO) systems with imperfect channel state information (CSI), where RIS-related channels are modeled by Rician fading. Considering the overhead and complexity in practical systems, we employ the low-complexity maximum ratio combining (MRC) beamforming at the base station (BS), and configure the phase shifts of the RIS based on long-term statistical CSI. Specifically, we first estimate the overall channel matrix based on the linear minimum mean square error (LMMSE) estimator, and evaluate the…

RIS辅助MU-MISO通信的环境感知码本设计：实现与性能分析

Environment-Aware Codebook Design for RIS-Assisted MU-MISO Communications: Implementation and Performance Analysis

本文针对RIS辅助MU-MISO通信，提出环境感知码本协议，通过分块信道训练和基于统计CSI的离线码本生成，显著降低导频开销与计算复杂度，并验证其优于环境无关码本。

存在EMI和信道老化的RIS辅助MISO系统性能分析

Performance Analysis of RIS-aided MISO Systems with EMI and Channel Aging

该研究针对存在EMI和信道老化的RIS辅助MISO系统，推导MRT预编码下下行SE闭式表达式，经仿真验证了莱斯视距分量、EMI、RIS单元数量与尺寸等因素对系统性能的影响，明确RIS可补偿信道老化带来的SE损失。

A Design of Low-Projection SCMA Codebooks for Ultra-Low Decoding Complexity in Downlink IoT Networks

This paper conceives a novel sparse code multiple access (SCMA) codebook design which is motivated by the strong need for providing ultra-low decoding complexity and good error performance in downlink Internet-of-things (IoT) networks, in which a massive number of low-end and low-cost IoT communication devices are served. By focusing on the typical Rician fading channels, we analyze the pair-wise probability of superimposed SCMA codewords and then deduce the design metrics for multi-dimensional constellation construction and sparse codebook optimization. For significant reduction of the decodi…

Beamforming in MISO Systems: Empirical Results and EVM-based Analysis

We present an analytical, simulation, and experimental-based study of beamforming Multiple Input Single Output (MISO) systems. We analyze the performance of beamforming MISO systems taking into account implementation complexity and effects of imperfect channel estimate, delayed feedback, real Radio Frequency (RF) hardware, and imperfect timing synchronization. Our results show that efficient implementation of codebook-based beamforming MISO systems with good performance is feasible in the presence of channel and implementation-induced imperfections. As part of our study we develop a framework …

Limited Feedback Massive MISO Systems with Trellis Coded Quantization for Correlated Channels

In this paper, we propose trellis coded quantization (TCQ) based limited feedback techniques for massive multiple-input single-output (MISO) frequency division duplexing (FDD) systems in temporally and spatially correlated channels. We exploit the correlation present in the channel to effectively quantize channel direction information (CDI). For multiuser (MU) systems with matched-filter (MF) precoding, we show that the number of feedback bits required by the random vector quantization (RVQ) codebook to match even a small fraction of the perfect CDI signal-to-interference-plus-noise ratio (SIN…

Coordinated Regularized Zero-Forcing Precoding for Multicell MISO Systems with Limited Feedback

We investigate coordinated regularized zero-forcing precoding for limited feedback multicell multiuser multiple-input single-output systems. We begin by deriving an approximation to the expected signal-to-interference-plus-noise ratio for the proposed scheme with perfect channel direction information (CDI) at the base station (BS). We also derive an expected SINR approximation for limited feedback systems with random vector quantization (RVQ) based codebook CDI at the BS. Using the expected interference result for the RVQ based limited feedback CDI, we propose an adaptive feedback bit allocati…

A Rate-Splitting Approach To Robust Multiuser MISO Transmission

For multiuser MISO systems with bounded uncertainties in the Channel State Information (CSI), we consider two classical robust design problems: maximizing the minimum rate subject to a transmit power constraint, and power minimization under a rate constraint. Contrary to conventional strategies, we propose a Rate-Splitting (RS) strategy where each message is divided into two parts, a common part and a private part. All common parts are packed into one super common message encoded using a shared codebook and decoded by all users, while private parts are independently encoded and retrieved by th…

RIS辅助的MISO系统的统计最优波束成形与遍历容量

Statistically Optimal Beamforming and Ergodic Capacity for RIS-aided MISO Systems

本文研究相关莱斯衰落下RIS辅助MISO系统的波束成形优化问题，提出基于半定松弛的迭代算法获取统计最优解，并推导了特殊情况下中断概率与遍历容量的闭式表达式，揭示了i.i.d.衰落及LoS分量对系统性能增益的影响规律。

可重构智能表面的控制信令：需要多少比特？

Control Signaling for Reconfigurable Intelligent Surfaces: How Many Bits are Needed?

本文研究RIS辅助系统中控制信令反馈比特数对性能的影响，提出一种面向视距场景的量化码本，以对数级反馈比特保证最小SNR损失，并通过仿真与理论分析验证其在莱斯信道下的有效性。

Joint Transceiver Design Algorithms for Multiuser MISO Relay Systems with Energy Harvesting

In this paper, we investigate a multiuser relay system with simultaneous wireless information and power transfer. Assuming that both base station (BS) and relay station (RS) are equipped with multiple antennas, this work studies the joint transceiver design problem for the BS beamforming vectors, the RS amplify-and-forward transformation matrix and the power splitting (PS) ratios at the single-antenna receivers. Firstly, an iterative algorithm based on alternating optimization (AO) and with guaranteed convergence is proposed to successively optimize the transceiver coefficients. Secondly, a no…

Robust Transmission in Downlink Multiuser MISO Systems: A Rate-Splitting Approach

We consider a downlink multiuser MISO system with bounded errors in the Channel State Information at the Transmitter (CSIT). We first look at the robust design problem of achieving max-min fairness amongst users (in the worst-case sense). Contrary to the conventional approach adopted in literature, we propose a rather unorthodox design based on a Rate-Splitting (RS) strategy. Each user's message is split into two parts, a common part and a private part. All common parts are packed into one super common message encoded using a public codebook, while private parts are independently encoded. The …

Optimization of Training and Feedback Overhead for Beamforming over Block Fading Channels

We examine the capacity of beamforming over a single-user, multi-antenna link taking into account the overhead due to channel estimation and limited feedback of channel state information. Multi-input single-output (MISO) and multi-input multi-output (MIMO) channels are considered subject to block Rayleigh fading. Each coherence block contains $L$ symbols, and is spanned by $T$ training symbols, $B$ feedback bits, and the data symbols. The training symbols are used to obtain a Minimum Mean Squared Error estimate of the channel matrix. Given this estimate, the receiver selects a transmit beamfor…

分布式可重构智能表面辅助无线通信：不完美CSI下的渐近分析

Distributed Reconfigurable Intelligent Surfaces Assisted Wireless Communication: Asymptotic Analysis under Imperfect CSI

本文研究了不完美CSI下分布式RISs辅助MISO系统的净和速率性能，推导了SINR与遍历净和速率的确定性等价物，并提出基于DE-S-CSI的低复杂度设计，在低开销与低功耗下实现高净和速率。