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221.
Device technologies for RF front-end circuits in next-generation wireless communications 总被引:1,自引:0,他引:1
Feng M. Shyh-Chiang Shen Caruth D.C. Huang J.-J. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2004,92(2):354-375
Next-generation high data rate wireless communication systems offer completely new ways to access information and services. To provide higher data speed and data bandwidth, RF transceivers in next-generation communications are expected to offer higher RF performance in both transmitting and receiving circuitry to meet quality of service. The semiconductor device technologies chosen will depend greatly on the tradeoffs between manufacturing cost and circuit performance requirements, as well as on variations in system architecture. It is hard to find a single semiconductor device technology that offers a total solution to RF transceiver building blocks in terms of system-on-chip integration. The choices of device technologies for each constituent component are important and complicated issues. We review the general performance requirement of key components for RF transceivers for next-generation wireless communications. State-of-the-art high-speed transistor technologies are presented to assess the capabilities and limitations of each technology in the arena of high data rate wireless communications. The pros and cons of each technology are presented and the feasible semiconductor device technologies for next-generation RF transceivers can be chosen upon the discretion of system integrators. 相似文献
222.
通过企业自备水厂加压泵站恒压供水节能改造实施,介绍了变频调速技术在供水系统节能技术改造中的应用,及其所带来的经济效益和社会效益。 相似文献
223.
Meng Xia Dong Cai Jianbo Feng Peng Zhao Jiakai Li Rongxin Lv Guiqiu Li Lulu Yan Wei Huang Yongpeng Li Zhuyin Sui Meng Li Hui Wu Yijun Shen Juanxiu Xiao Dong Wang Qi Chen 《Advanced functional materials》2023,33(26):2214813
Sorption-based atmospheric water generation (SAWG) is a promising strategy to alleviate the drinkable water scarcity of arid regions. However, the high-water production efficiency remains challenging due to the sluggish sorption/desorption kinetics. Herein, a composite sorbent@biomimetic fibrous membrane (PPy-COF@Trilayer-LiCl) is reported by mimicking nature's Murray networks, which exhibits outstanding water uptake performance of 0.77–2.56 g g−1 at a wide range of relative humidity of 30%–80% within 50 min and fast water release capacity of over 95% adsorbed water that can be released within 10 min under one sun irradiation. The superior sorption–desorption kinetics of PPy-COF@Trilayer-LiCl are enabled by the novel hierarchically porous structure, which is also the critical factor to lead a directional rapid water transport and vapor diffusion. Moreover, as a proof-of-concept demonstration, a wearable SAWG device is established, which can operate 10 sorption–desorption cycles per day in the outdoor condition and produce a high yield of clean water reaching up to 3.91 kg m−2 day−1. This study demonstrates a novel strategy for developing advanced solar-driven SAWG materials with efficient water sorption–desorption properties. 相似文献
224.
225.
电信网的网络管理一直是电信运营商非常关心的问题.软交换作为一种新兴的技术,在网络管理方面体现出了许多新特点.本文针对软交换网络的技术特点和应用模式,提出了对软交换网管系统的新增功能要求,并对软交换网管建设中的要点提出了建议. 相似文献
226.
Lai-Huei Wang Chung-Ching Shen Shenpei Wu Shuvra S. Bhattacharyya 《Journal of Signal Processing Systems》2013,71(3):275-286
In recent work, a graphical modeling construct called “topological patterns” has been shown to enable concise representation and direct analysis of repetitive dataflow graph sub-structures in the context of design methods and tools for digital signal processing systems (Sane et al. 2010). In this paper, we present a formal design method for specifying topological patterns and deriving parameterized schedules from such patterns based on a novel schedule model called the scalable schedule tree. The approach represents an important class of parameterized schedule structures in a form that is intuitive for representation and efficient for code generation. Through application case studies involving image processing and wireless communications, we demonstrate our methods for topological pattern representation, scalable schedule tree derivation, and associated dataflow graph code generation. 相似文献
227.
228.
Erick González-Rodríguez Holger Maune Yuliang Zheng Mohsen Sazegar Lufei Shen Ibrahim Asghar Shah Dirk Dahlhaus Klaus Hofmann Rolf Jakoby 《AEUE-International Journal of Electronics and Communications》2013,67(12):1107-1117
In this paper the bit error rate performance and error vector magnitude of a tunable impedance matching network is analyzed assuming QPSK, 16-QAM and 64-QAM digital modulation schemes. The characterized tunable impedance matching network is based on barium–strontium–titanate ferroelectric thick-film varactors. Inherent dispersive behavior is subsumed into the forward transmission of the passive device. Due to this nonlinear phase response, in general to maximize the overall system performance, an agile tuning of the varactor values is demonstrated, taking into account the phase and group delay of s21 parameter. Detailed signal simulation results based on measured data of a testbed are presented. The influence of varying matched impedances on the tuning behavior with different modulation bandwidths is discussed at a center frequency of 1.9 GHz. 相似文献
229.
To improve the performance of transmission by reducing the number of transmission and network overhead of wireless single-hop networks, this paper presents a high efficient multipacket decoding approach for network coding (EMDNC) in wireless networks according to the idea of encoding packets which cannot be decoded and are stored in buffer by receiving nodes, the lost packets can be recovered from these encoded packets. Compared with the network coding wireless broadcasting retransmission (NCWBR), EMDNC can improve the efficiency of decoding and reduce the number of retransmission and transmission delay. Simulation results reveal that EMDNC can effectively reduce the number of retransmission and network overhead. 相似文献
230.
This article proposes a new angle difference of directions arrival (ADOA) estimation algorithm. It can estimate the values of ADOA of incidence signals even under channel incoherence environments. It performs an eigenvalue decomposition of a covariance matrix to obtain signal and noise subspace eigenvectors, then estimates the values of ADOA of signals based on the orthogonality between the noise subspace eigenvectors and steering vectors. Its main advantage is that the performance is not degenerated by array elements channel incoherence. In addition, the system complexity is also reduced. Finally, the numerical simulations have been conducted to verify the performance improvement of this algorithm. 相似文献