Sparse array of sub-surface aided blockage-free multi-user mmWave communication systems

Recently, Reconfigurable Intelligent Surfaces (RISs) have drawn intensive attention in the realization of the smart radio environment. However, existing works mainly consider the RIS as a whole uniform plane, which may be unrealistic to be installed on the facade of buildings when the RIS is extremely large. In contrast, this paper investigates a practical Sparse Array of Sub-surface (SAoS) deployment of the RIS for uplink multi-user millimeter Wave (mmWave) communication systems, in which the Mobile Stations (MSs) are distributed in the blind coverage area due to the blockage. In order to exploit the benefits of the sparse deployment, the correlation of the effective channel is firstly investigated. Then the approximation and lower bounds of the ergodic spectral efficiency are derived under frequency and spatial multiplexing scenarios, respectively. Based on the autocorrelation of the effective channel, we obtain an optimal reflect coefficient design as well as the deployment guidelines of RIS tiles. Moreover, the RIS tile scheduling algorithms are also proposed. Numerical results show that the ergodic spectral efficiency approximation matches well with the Monte Carlo result under frequency multiplexing scenarios, and the lower bound is tight under spatial multiplexing scenarios only when the effective channel is strongly correlated. On the basis of the RIS tile scheduling algorithm and the reflect coefficient design, the system performance can be significantly improved under frequency multiplexing scenarios. On the other hand, by deploying more sparse RIS tiles, we can increase the multiplexing gain under spatial multiplexing scenarios.     

毫米波MIMO系统中迭代最小均方误差混合波束成形算法

混合波束成形结构能有效解决毫米波MIMO系统中射频链路受限的问题,但要设计性能较优的混合波束成形算法仍然存在困难.为了实现更高的频谱利用率,提出了一种性能较优的迭代最小均方误差(Alt-MMSE)混合波束成形算法.该算法利用数字矩阵的正交特性,首先进行初始数字矩阵设计,然后通过最小化发送信号与接收信号的均方误差不断迭代更新数字矩阵,在每一次迭代过程中,通过更新后的数字矩阵得到模拟矩阵的相位信息.仿真结果表明,与OMP混合波束成形算法和基于矩阵分解的混合处理方案相比,该算法具有更优的性能且更接近于纯数字波束成形.     

60 GHz broadband MAC system design for cable replacement in machine vision applications

In this paper, we present a wireless 60 GHz OFDM transceiver for a high-throughput GigE Vision standard compliant color CCD camera system used in machine vision applications. The OFDM transceiver provides net data rates up to 3.9 Gb/s. The medium access controller (MAC) offers the reliable GigE point-to-point cable replacement functionality with special support of an asymmetrical downlink scenario. The main focus is on the high throughput MAC design for frame based wireless transmissions and the integration onto a hardware platform. The OFDM baseband processor and the MAC were fully implemented in FPGA technology. The performance of the system was theoretically analyzed and measured in an indoor environment. The developed system fulfills the high throughput requirement as well as the low latency requirement of the used industrial HD video camera system.     

Deep frameworks based on residual dense network and reinforcement learning for mmWave massive MIMO systems

In millimeter wave (mmWave) massive multiple-input-multiple-output (MIMO) systems, hybrid precoding plays a pivotal role in reducing complexity and cost while providing a good spectral efficiency. However, implementation of digital precoders with large number of antennas is difficult due to hardware constraints, while analog precoders offer confined performance. This leads to high computational complexity and cannot fully exploit the spatial information. Previous studies on hybrid precoding were based on exhaustive search solutions or greedy schemes, which result in higher complexity system performance. To face these challenges, this paper proposes deep hybrid precoding framework with phase quantization and residual dense network to design the matrix of analog and digital precoders. The proposed deep hybrid precoding technique consists of offline training stage and online deployment stage. In offline training stage, hybrid precoding is obtained assuming the approximate phase quantization. While in the online deployment stage, the matrix of analog precoding is calculated by exchanging approximate phase quantization with ideal phase and grouping the analog precoding vectors. In this paper, we also propose a deep reinforcement learning-based hybrid precoding. It consists of a deep reinforcement learning with employing convolutional neural network and long short-term memory (LSTM) methods. In our proposed frameworks, structures of proposed techniques are trained for maximum spectral efficiency. Our proposed techniques are compared with other precoding techniques. Results illustrate that the proposed techniques outperforms the other precoding techniques in terms of the spectral efficiency.     

Space‐time block coding in millimeter wave large‐scale MIMO‐NOMA transmission scheme

In this paper, we introduce a new wireless system architecture using space‐time block coding schemes (STBC) and non‐orthogonal multiple access (NOMA) in millimeter wave (mmWave) large‐scale MIMO systems. The proposed STBC mmWave large‐scale MIMO‐NOMA system utilizes two MIMO subarrays, transmitting data over two channel vectors to mobile users. To reduce the communication overhead and latency in the system, we utilize random beamforming with optimal coefficients at the base station and random‐near random‐far user pairing in implementing the NOMA scheme. Our results show that the proposed STBC mmWave large‐scale MIMO‐NOMA technique significantly outperforms the previous counterparts.     

基于5G的毫米波Massive MIMO基本构架综述

随着社会的发展,科技不断进步。过去几十年中,无线蜂窝网络一直迅速发展,现阶段人们主要研究5G技术。5G的发展前景与需求是为了应对未来移动数据流量爆炸性增长、海量设备连接、不断涌现的各类新业务和应用场景,同时,与行业深度融合,满足垂直行业终端互联的多样化需求,实现真正的"万物互联",为社会经济数字化转型奠定基石。     

77‐GHz mmWave antenna array on liquid crystal polymer for automotive radar and RF front‐end module

This paper introduces a low‐cost, high‐performance mmWave antenna array module at 77 GHz. Conventional waveguide transitions have been replaced by 3D CPW‐microstrip transitions which are much simpler to realize. They are compatible with low‐cost substrate fabrication processes, allowing easy integration of ICs in 3D multi‐chip modules. An antenna array is designed and implemented using multilayer coupled‐fed patch antenna technology. The proposed 16 × 16 array antenna has a fractional bandwidth of 8.4% (6.5 GHz) and a 23.6‐dBi realized gain at 77 GHz.     

基于改进粒子群算法的毫米波大规模MIMO混合预编码方案

针对毫米波大规模多输入多输出（MIMO）系统中基于传统粒子群优化（PSO）算法的混合预编码方案,在迭代后期收敛速度较慢以及容易陷入局部最优值的问题,提出了一种基于改进PSO算法的混合预编码方案。首先,随机初始化粒子的位置矢量和速度矢量,并以最大化系统和速率为目标求解初始群体最优位置矢量;其次,更新位置矢量和速度矢量,并随机地选择更新后的两个粒子的个体历史最优位置矢量进行加权求和作为新的个体历史最优位置矢量,从中挑选出若干个使系统和速率最大的粒子,将其个体历史最优位置矢量的加权平均值作为新的群体最优位置矢量,并与之前的群体最优位置矢量比较,经过多次迭代形成最终的群体最优位置矢量即为所求的最佳混合预编码矢量,并对其进行归一化;最后,根据归一化后的混合预编码矢量设计最终的模拟预编码矩阵和数字预编码矩阵。仿真结果表明,与基于传统PSO算法的混合预编码方案相比,所提改进方案在收敛速度与和速率上都得到优化;其收敛速度提高约100%,且性能可以达到全数字预编码方案的90%,因此,该改进方案能够有效提升系统性能且加快收敛。     

Propagation Characterization and Analysis for 5G mmWave Through Field Experiments

The 5G network has been intensively investigated to realize the ongoing early deployment stage as an effort to match the exponential growth of the number of connected users and their increasing demands for high throughput, bandwidth with Quality of Service (QoS), and low latency. Given that most of the spectrums below 6 GHz are nearly used up, it is not feasible to employ the traditional spectrum, which is currently in use. Therefore, a promising and highly feasible effort to satisfy this insufficient frequency spectrum is to acquire new frequency bands for next-generation mobile communications. Toward this end, the primary effort has been focused on utilizing the millimeter-wave (mmWave) as the most promising candidate for the frequency spectrum. However, though the mmWave frequency band can fulfill the desired bandwidth requirements, it has been demonstrated to endure several issues like scattering, atmospheric absorption, fading, and especially penetration losses compared to the existing sub-6 GHz frequency band. Then, it is fundamental to optimize the mmWave band propagation channel to facilitate the practical 5G implementation for the network operators. Therefore, this study intends to investigate the outdoor channel characteristics of 26, 28, 36, and 38 GHz frequency bands for the communication infrastructure at the building to the ground floor in both Line of Sight (LOS) and Non-Line of Sight (NLOS) environments. The experimental campaign has studied the propagation path loss models such as Floating-Intercept (FI) and Close-In (CI) for the building to ground floor environment in LOS and NLOS scenarios. The findings obtained from the field experiments clearly show that the CI propagation model delivers much better performance in comparison with the FI model, thanks to its simple setup, accuracy, and precise function.     

一种基于SIC-CDM的低复杂度混合波束赋形方案

为了平衡毫米波大规模多输入多输出系统的性能和硬件开销,降低系统功耗,以频谱效率为优化目标,在部分连接结构下提出了一种收发端联合设计的低复杂度混合波束赋形方案。首先,基于连续干扰消除将原始优化问题转化为多个子阵的速率优化问题;然后,利用坐标下降法完成模拟波束赋形矩阵设计;最后,引入等效信道矩阵大幅降低矩阵维度,再对其进行奇异值分解获得数字波束赋形矩阵。仿真结果表明,与其他算法相比,所提算法在系统功耗降低的同时保持了较优的性能,且性能逼近部分连接结构的最优方案。