To meet the future demand for huge traffic volume of wireless data service, the research on the fifth generation (5G) mobile communication systems has been undertaken in recent years. It is expected that the spectral and energy efficiencies in 5G mobile communication systems should be ten-fold higher than the ones in the fourth generation (4G) mobile communication systems. Therefore, it is important to further exploit the potential of spatial multiplexing of multiple antennas. In the last twenty years, multiple-input multiple-output (MIMO) antenna techniques have been considered as the key techniques to increase the capacity of wireless communication systems. When a large-scale antenna array (which is also called massive MIMO) is equipped in a base-station, or a large number of distributed antennas (which is also called large-scale distributed MIMO) are deployed, the spectral and energy efficiencies can be further improved by using spatial domain multiple access. This paper provides an overview of massive MIMO and large-scale distributed MIMO systems, including spectral efficiency analysis, channel state information (CSI) acquisition, wireless transmission technology, and resource allocation.
標簽： Large-scale Antenna Systems
上傳時間： 2020-05-27
上傳用戶：shancjb
Due to the asymmetry between the amount of data traffic in the downlink and uplink direction of nowadays and future wireless networks, a proper design of the transceivers in the broadcast channel is inevitable in order to satisfy the users’ demands on data rate and transmission quality. This book deals with the optimi- zation-based joint design of the transmit and receive filters in a MIMO broadcast channel in which the user terminals may be equipped with several antenna ele- ments.
上傳時間： 2020-05-28
上傳用戶：shancjb
Digital mobile wireless communication and the Internet have undergone a fantastic growth in the last few years and, despite originating from two different worlds, they are converging. This convergence corresponds to the evolution of mobile systems towards the highest broadband data transmissions (GSM, EDGE/GPRS, UMTS then HSDPA), while the computing world gets equipped with wireless technologies such as Wi-Fi or Wi-Max.
標簽： Reconfigurable Systems Mobile Radio
上傳時間： 2020-06-01
上傳用戶：shancjb
A mobile ad-hoc network (MANET) is formed by multiple moving nodes equipped with wireless transceivers. The mobile nodes communicate with each other through multi-hop wireless links, where every node can transmit and receive information. Mobile ad-hoc networks have become increasingly important in areas where deployment of communications infrastructure is difficult.
標簽： Telecommunications Modeling
上傳時間： 2020-06-01
上傳用戶：shancjb
Thanks to the advances in micromachining fabrication technologies and significant cost reduction due to mass production, miniature sensors of angular rate, or gyroscopes, found their way into the everyday life of every user of modern gadgets, such as smart phones, tablets or even wristwatches. Often without realising, many of us are carrying in our pockets fully equipped with all necessary sensors complete inertial navigation systems that not so long ago were available only for advanced vehicles in sea, land, air or space. Accelerometers and gyroscopes are found in specifications of any gadget supposed to react to user movements. And one of the most commonly used type of gyroscopes used to developed these systems is Coriolis vibratory gyroscope (CVG).
標簽： Gyroscopes Vibratory Coriolis
上傳時間： 2020-06-06
上傳用戶：shancjb
The term “ smart grid ” defi nes a self - healing network equipped with dynamic optimiza- tion techniques that use real - time measurements to minimize network losses, maintain voltage levels, increase reliability, and improve asset management. The operational data collected by the smart grid and its sub - systems will allow system operators to rapidly identify the best strategy to secure against attacks, vulnerability, and so on, caused by various contingencies. However, the smart grid fi rst depends upon identifying and researching key performance measures, designing and testing appropriate tools, and developing the proper education curriculum to equip current and future personnel with the knowledge and skills for deployment of this highly advanced system.
上傳時間： 2020-06-07
上傳用戶：shancjb
鋰電池BMS管理技術(shù)是移動機器人的關(guān)鍵技術(shù),本文設(shè)計了基于bq76PL455、STM32F103的鋰電池管理系統(tǒng),實現(xiàn)了電池組電壓、電流、過壓、過流等狀態(tài)監(jiān)測;系統(tǒng)配置均衡電路,電池充電過程中若出現(xiàn)電池單體電壓不平衡現(xiàn)象,會觸發(fā)均衡電路,進而提高電池的安全性,延長使用壽命。Lithium battery BMS management technology is the key technology of mobile robot.The lithium battery management system based on bq76PL455 and STM32F103 is proposed to realize the monitoring of battery pack voltage,current,overvoltage and overcurrent.The system is equipped with equalization circuit.When the battery cell voltage imbalance occurs,the equalization circuit is triggered to improve the safety and service life of the battery.
標簽： 移動機器人 鋰電池 bms管理系統(tǒng)
上傳時間： 2022-04-02
上傳用戶：
本文首次設(shè)計并驗證了基于macom三合一芯片設(shè)計的光模塊電路,該電路旨在提供一種滿足SFF-8472中規(guī)定的數(shù)字診斷功能的低成本SFP+模塊。電路采用激光器驅(qū)動、限幅放大器、控制器以及時鐘恢復單元集成的單芯片,在保證高精度數(shù)字診斷功能基礎(chǔ)上,實現(xiàn)了低成本高可靠的特點。該電路在光接收接口組件與激光器驅(qū)動和限幅放大器單元的限幅放大器部分之間接入濾波器來提高模塊的靈敏度及信號質(zhì)量。在控制器單元的數(shù)字電位器的引腳上采用外加電阻的方式避免出現(xiàn)上電不發(fā)光的故障問題。該研究結(jié)果為下一代SFP-DD光模塊設(shè)計與開發(fā)工作,奠定了一定的理論與實踐基礎(chǔ)。This paper designs and validates the optical module circuit based on the MACOM Trinity chip for the first time.This circuit aims to provide a low-cost SFP module which meets the digital diagnosis function specified in SFF-8472.The circuit uses a single chip integrated with laser driver,limiting amplifier,controller and clock recovery unit.On the basis of ensuring high precision digital diagnosis function,it achieves the characteristics of low cost and high reliability.The circuit connects a filter between the optical receiving interface module and the limiting amplifier part of the laser driver and limiting amplifier unit to improve the sensitivity and signal quality of the module.The pin of the digital potentiometer in the controller unit is equipped with an external resistance to avoid the problem of power failure.The research results lay a theoretical and practical foundation for optical module design in high-speed data center.
上傳時間： 2022-04-03
上傳用戶：
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