共查询到19条相似文献,搜索用时 62 毫秒
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一种宽带的InGaP/GaAs HBT 再生频率分频器 总被引:1,自引:1,他引:0
A dynamic divide-by-two regenerative GaP/GaAs heterojunction bipolar transistors (HBTs) frequency divider (RFD) is presented in a 60-GHz-fT Intechnology. To achieve high operation bandwidth, active loads instead of resistor loads are incorporated into the RFD. On-wafer measurement shows that the divider is operating from 10 GHz up to at least 40 GHz, limited by the available input frequency. The maximum operation frequency of the divider is found to be much higher than fT/2 of the transistor, and also the divider has excellent input sensitivity. The divider consumes 300.85 mW from 5 V supply and occupies an area of 0.47 × 0.22 mm^2. 相似文献
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主要针对WCDMA网络规划中切换问题进行研究和分析。首先从移动通信系统切换的概念和功能入手.介绍常见的几种切换方式.并对WCDMA系统中的切换进行分类。然后介绍了切换流程以及切换过程所包含的测量控制、切换判决和切换执行等各个步骤。最后对切换带来的切换比例和开销问题进行了仿真分析,并给出了WCDMA规划中合理的切换比例和相关参数的设置。 相似文献
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WCDMA系统中切换的研究 总被引:1,自引:1,他引:0
描述了WCDMA系统切换机制,着眼于切换的各种参数对切换的影响,切换对系统性能的影响.着重分析了同频软切换和异频硬切换这两种切换形式在同频软切换中详细分析了各种不同情况触发的软切换.并结合运营商的实际情况提出了一些建议。 相似文献
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WCDMA的切换可以分为软切换(包括更软切换)、硬切换、前向切换以及系统间切换。一个典型的切换过程包括测量控制、测量报告、切换判决和执行切换。详细介绍了WCDMA的硬切换技术、信令流程,以及在现网中的实现。建议设备厂商尽量支持各种硬切换触发方式,使运营商有更多的选择。希望在正式商用时,硬切换不成为影响网络质量的重要因素。 相似文献
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Safarian A. Anand S. Heydari P. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2006,53(12):1413-1417
A comprehensive analytical study of regenerative frequency dividers (RFD) is presented. The study includes two fundamental modes of operation in RFDs, namely locked (or stable) and quasi-locked modes, and the study also covers the transition from free-running oscillation to quasi-locked, and ultimately to locked operation mode. Differential equations characterizing the RFD behavior for both operation modes as well as the transition between the two are derived. An RFD circuit for Bluetooth applications was designed and fabricated in a 65-nm CMOS process with a supply voltage of 1.2 V. Measurement results of the RFD prototype verify the accuracy of the proposed analytical models 相似文献
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马宁李春明万仁辉武琳栋 《电信工程技术与标准化》2014,(7):67-71
中国移动TD-LTE网络宏站覆盖有D频段和F频段两个频段,对应有同频切换和异频切换两种方式,两种切换过程基本相同。同频切换前SINR会比较差,切换后SINR提升比较明显,异频切换时由于有频率隔离,SINR值一直比较趋于稳定,切换后SINR值也会有所提升,但是会有异频测量GAP时间占用。两种切换方式都会提升速率,但从大量测试数据分析来看,异频切换速率提升幅度高于同频切换。 相似文献
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从现网统计发现同步切换与异步切换的切出数量比大约是1:4,异步切换的切出成功率比同步切换的切出成功率高1.6%,为了提高切出成功率,通过对同步切换的切出成功率低的原因进行细致分析,得出将同步切换调整为异步切换的合理性,并在现网推广实施后,有效改善了切出成功率。 相似文献
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TD-SCDMA系统接力切换技术及仿真 总被引:2,自引:0,他引:2
越区切换是蜂窝移动通信系统中的关键技术之一,第三代移动通信系统TD-SCDMA中采用了一种新型的越区切换技术—接力切换。文章在完整阐述其基本概念、切换过程和切换算法的基础上,对比硬切换方式,建立切换仿真模型并进行了仿真,得到上行传输功率和FTP业务上传响应时间的性能参数曲线。仿真结果证明,接力切换在降低上行干扰、缩短切换时延、降低掉话率方面性能更加优良。 相似文献
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Nurul ‘Ain Amirrudin Sharifah Hafizah Syed Ariffin Nik Noordini Nik Abd. Malik Nurzal Effiyana Ghazali 《Wireless Personal Communications》2017,97(2):1929-1946
Handover management is one of the main factors representing the effectiveness of every wireless network technology. Due to the special characteristics of a femtocell, unnecessary handover occurs more frequently. This issue has attracted interest in developing a new handover algorithm in femtocell network. The standard handover algorithm relies on Reference Signal Received Power or Reference Signal Received Quality (RSRQ) level. However, this technique causes an unnecessary handover and reduces the user throughput. Mobility prediction is one of a popular technique to be implemented in handover algorithm. This paper analyzes the handover performance in femtocell network by using two types of handover algorithm which are standard A2-A4-RSRQ handover algorithm and proposed prediction handover algorithm. The analysis is performed in terms of the number of handover, the number of unnecessary handover, and the user throughput. The root cause of user throughput degradation is also analyzed. The results show that the prediction handover algorithm provides better performance than the A2-A4-RSRQ handover algorithm in terms of the number of handover and user throughput. 相似文献
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Zhao W. Tafazolli R. Evans B.G. 《Selected Areas in Communications, IEEE Journal on》1997,15(8):1657-1671
This paper evaluates the internetwork handover performance in a GSM and satellite integrated mobile communication system. The performance evaluation is based on an analytical model developed for internetwork handover. The handover performance parameters considered are the handover position, unnecessary handover probability, and call-dropping probability. Handover initiation is based on the signal level and distance measurement. The results are compared with those of the GSM handover performance. The analysis shows that the performance achieved in internetwork handover can be similar to those of the GSM handover with the considered handover initiation scheme 相似文献
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Mohammed A. Ben-Mubarak Borhanuddin Mohd. Ali Nor Kamariah Noordin Alyani Ismail Chee Kyun Ng 《Wireless Personal Communications》2013,71(2):1421-1442
It is well known that WiMAX is a broadband technology that is capable of delivering triple play (voice, data, and video) services. However, mobility in WiMAX system is still a main issue when the mobile station (MS) moves across the base station (BS) coverage and be handed over between BSs. Among the challenging issues in mobile WiMAX handover are unnecessary handover, handover failure and handover delay, which may affect real-time applications. The conventional handover decision algorithm in mobile WiMAX is based on a single criterion, which usually uses the received signal strength indicator (RSSI) as an indicator, with the other fixed handover parameters such as handover threshold and handover margin. In this paper, a fuzzy logic based self-adaptive handover (FuzSAHO) algorithm is introduced. The proposed algorithm is derived from the self-adaptive handover parameters to overcome the mobile WiMAX ping-pong handover and handover delay issues. Hence, the proposed FuzSAHO is initiated to check whether a handover is necessary or not which depends on its fuzzy logic stage. The proposed FuzSAHO algorithm will first self-adapt the handover parameters based on a set of multiple criteria, which includes the RSSI and MS velocity. Then the handover decision will be executed according to the handover parameter values. Simulation results show that the proposed FuzSAHO algorithm reduces the number of ping-pong handover and its delay. When compared with RSSI based handover algorithm and mobility improved handover (MIHO) algorithm, respectively, FuzSAHO reduces the number of handovers by 12.5 and 7.5 %, respectively, when the MS velocity is <17 m/s. In term of handover delay, the proposed FuzSAHO algorithm shows an improvement of 27.8 and 8 % as compared to both conventional and MIHO algorithms, respectively. Thus, the proposed multi-criteria with fuzzy logic based self-adaptive handover algorithm called FuzSAHO, outperforms both conventional and MIHO handover algorithms. 相似文献
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Bin Liu Nadia Boukhatem Philippe Martins Philippe Bertin 《Wireless Communications and Mobile Computing》2014,14(5):565-582
Next generation mobile networks will provide seamless mobility between existing cellular systems and other wireless access technologies. To realize a seamless vertical handover (inter‐radio access technology handover) among these different access technologies, a multi‐interfaced mobile station (i.e., multihomed) is a good approach to provide better handover performance in terms of packet loss rate and handover latency. In this article, we propose a novel layer 2 multihoming approach for inter‐radio access technology handover between Universal Mobile Telecommunications System (UMTS) and Worldwide Interoperability for Microwave Access (WiMAX) in both integrated and tight coupling architectures. This layer 2 multihoming approach has the ability of enabling either soft handover or make‐before‐break handover to adapt to mobility scenarios for the sake of a lossless and short latency handover procedure. Our simulation results show that, in case of handover from UMTS to WiMAX for transmission control protocol (TCP) traffics, the layer 2 multihoming approach can achieve a lossless and zero latency handover procedure by enabling soft handover. In case of handover from WiMAX to UMTS, because of the fact that the performance gain of soft handover is more affected by the differences of bandwidth and transmission delay between these wireless links, the make‐before‐break handover is preferred to achieve lossless and short latency handover procedure. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献