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《Digital Communications & Networks》2022,8(6):1115-1121
Millimeter Wave (mmWave) communication has been widely acknowledged as an attractive solution to address high-speed transmission of massive data in 5G and beyond 5G systems due to the promising spectrum availability. However, mmWave signals are highly susceptible to blockage and may suffer from rapidly changing channels. Thus, directional/beam tracking becomes imperative yet essential for robust mmWave communications. To address this challenge, we propose a robust beam tracking scheme for mmWave Heterogeneous Networks (HetNets) with multi-connectivity. Different from most existing schemes, the proposed beam tracking scheme is effective for outage events. We first discuss the μWave-assisted beam tracking procedure with and without candidate beams, and then analyze the inherent correlation between mmWave link quality and the operating beamwidth and occlusion range to derive the optimal beamwidth. Theoretical and numerical results show that the proposed beam tracking scheme can improve the robustness of mmWave communications while guaranteeing the rate performance. 相似文献
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Janmoni Borah Tasher Ali Sheikh Joyatri Bora 《International Journal of Communication Systems》2023,36(5):e5422
The paper proposes a novel cell sleeping mechanism for enhancing network energy-efficiency and to combat dynamic downlink interferences linked with mobile Small Cells (mSCs) in a 5G Heterogeneous Cellular Network (HetCN). The proposed Dynamic Mobile Cell Sleeping Mechanism (DMCSM) allows deployed vehicle-mounted mSCs to dynamically go into sleep based on the calculated distances of users from its serving mSCs BS. With this mechanism, vehicular mSCs during mobility dynamically calculate their distances with the Macrocell (MC) users. The mSCs go into sleep or get deactivated for a while based on the calculated distance and the cell radius defined for mSCs. The mSCs will get active and starts to provide services to the users that are found within their coverage radius. The setup 5G HetCN is investigated with a MC superimpose with fixed SCs (fSCs) and mobile SCs (mSCs). The proficiency of DMCSM is investigated with the exploitation of existing sub 6 GHz groups at MCs and the millimeter wave (mmWave) spectrums at deployed fSCs and mSCs. The network downlink performance metrics: user throughput, sumrate, energy-efficiency, and outage probability, have been explored. The work also depicts a comparison of the proposed DMCSM mechanism with the author's previously proposed ICI mitigation techniques. 相似文献
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Md. Omor Faruk Joarder Jafor Sadique Kanapathippillai Cumanan Shaikh Enayet Ullah 《ETRI Journal》2023,45(2):213-225
Physical layer security (PLS) can improve the security of both terrestrial and nonterrestrial wireless communication networks. This study proposes a simplified framework for nonterrestrial cyclic prefixed orthogonal variable spreading factor (OVSF)-encoded multiple-input and multiple-output nonorthogonal multiple access (NOMA) systems to ensure complete network security. Various useful methods are implemented, where both improved sine map and multiple parameter-weighted-type fractional Fourier transform encryption schemes are combined to investigate the effects of hybrid PLS. In addition, OVSF coding with power domain NOMA for multi-user interference reduction and peak-to-average power ratio (PAPR) reduction is introduced. The performance of -rated convolutional, turbo, and repeat and accumulate channel coding with regularized zero-forcing signal detection for forward error correction and improved bit error rate (BER) are also investigated. Simulation results ratify the pertinence of the proposed system in terms of PLS and BER performance improvement with reasonable PAPR. 相似文献
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Selam Biru Satyasis Mishra Ram Sewak Singh Shanko Chura Sunita Satapathy 《International Journal of Communication Systems》2024,37(8):e5743
The advanced wireless communication system requires abridged energy consumption, enhanced data rate, and good signal coverage. The massive MIMO technology for 5G systems has been developed to accommodate several users simultaneously with superior throughput. The claim for high data rate wireless communication services is expanding quickly as time goes. Thus, the key difficulty is that as the number of users grows, the number of phase shifters grows as well, causing the system to consume more power; as a result, the system's energy efficiency decreases. Hybrid beamforming has recently emerged as an attractive technique for millimeter-wave (mmWave) communication systems. The analog beamformer in the RF domain and digital beamformer in the baseband are coupled through a minimal number of RF chains in hybrid beamforming architecture. Hybrid beamforming utilizes fewer RF (radio frequency) chains than the total number of antennas to have a lower energy consumption design. The hybrid beamforming for a mmWave-based massive MIMO system through different phase shifter selection mechanisms is proposed to achieve the highest energy efficiency for mmWave communications systems. The fully connected with phase shifter selection, sub-connected with phase shifter selection (SPSS), and fully connected and sub-connected with phase shifter selection with halved and doubled switches are considered for this research. The simulation results show the SPSS with halved switch outperforms on energy efficiency. 相似文献
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非正交多址接入(non-orthogonal multiple access,NOMA)和毫米波大规模多输入多输出(multiple-input multiple-output,MIMO)的结合能够支持未来无线通信网络的巨流量大连接需求。研究了上行链路毫米波大规模MIMO-NOMA系统中的功率最小化问题,提出了基于群体串行干扰消除(group-levelsuccessiveinterference cancellation,GSIC)的混合波束成形毫米波MIMO-NOMA上行传输系统新架构。具体来说,根据信道增益对用户进行群体划分,不同群体用户由NOMA服务,群体内用户采用空分多址区分。通过给不同群体设计模拟波束成形矩阵,对数字波束成形和功率控制进行联合优化,提出了一种并行迭代算法来解决优化问题。仿真结果表明,所提出的新架构在总功率方面优于传统的基于分簇和用户级串行干扰消除的毫米波大规模MIMO-NOMA。 相似文献
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波束管理是毫米波通信的重要研究内容,5G NR（New Radio）协议中已完整设计了用户在初始接入和连接状态下与基站确定最佳通信波束的流程,然而B5G(Beyond Fifth Generation)场景将使用52.6 GHz以上甚至更高的通信频率,需要更大规模的天线单元对抗路损,导致波束管理在初始接入过程中的信令开销和时延急剧增加。为此,在5G NR协议现有框架的基础上,针对52.6 GHz以上的高频段重新设计了一种专用于波束扫描的信号块（Beam Sweeping Block,BSB）,并提出一种两阶段增强型波束管理机制,用于在初始接入过程中快速确定用户和基站的最佳通信波束,进而完成同步和小区搜索。仿真结果表明,相对于NR中现有的波束管理机制,所提出的增强型波束管理方案可在保证接入性能的前提下,大幅降低初始接入时延。 相似文献
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In this paper, a dynamic and location‐based power allocation mechanism is proposed which could be adopted at both macrocell (MC) and overlaid fixed/mobile small cells (SCs) to mitigate inter‐cell interference (ICI) effects in heterogeneous cellular networks (HetCNs). The proposed Dynamic Power Allocation based on User Location (DPAUL) mechanism allows both MCs and deployed fixed/mobile SCs to dynamically allocate transmit power to its serving base stations (BSs) based on the location of a user in the cell. The paper illustrates the mitigation of dynamic downlink interferences occurring due to the mobility of SCs and users. The mobility of cell and its users is analyzed by introducing the Cell‐User mobility (CUM) model in the network. The proposed DPAUL mechanism is compared with the authors' other ICI mitigation techniques: Dynamic Fixed Region Cooperation (DFRC) and Dynamic Power Allocation Mechanism (DPAM). The network metrics Sumrate, User throughput, Energy‐efficiency, and Outage probability are investigated with allocation of sub 6 GHz and mmWave spectrums at MCs and fSCs/mSCs, respectively. 相似文献
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Numerous wearable technology companies have recently developed several head‐mounted display (HMD) products for virtual reality (VR) services. 5G wireless networks aim at providing high‐quality 3D multimedia services such as VR, augmented reality, and mixed reality. In this study, we examine the application of millimeter‐wave (mmWave) technology to realize low‐latency wireless communication between an HMD and its content server. However, the propagation characteristics of mmWave present several challenges such as the deafness, blockage, and beam alignment problems, and interference among content servers. In this study, we focus on an environment that provides VR services in the mmWave band and introduce existing techniques for addressing such challenges. In addition, we employ a commercialized IEEE 802.11ad VR dongle to measure the actual data rate of an mmWave VR application and identify the degree to which the performance deteriorates when the above problems occur. Finally, we verify the feasibility of the proposed solutions through a simulation of several VR scenarios in the mmWave band. 相似文献
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