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本文对CDMA蜂窝网络中的无线资源管理研究作综述。内容包括功率控制、接纳控制、越区切换和无线分调度等方面,并考虑了多种业务下的服务质量。 相似文献
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The complementary characteristics of wireless local area networks (WLANs) and wideband code division multiple access (CDMA)
cellular networks make it attractive to integrate these two technologies. How to utilize the overall radio resources optimally
in this heterogeneous integrated environment is a challenging issue. This paper proposes an optimal joint session admission
control scheme for multimedia traffic that maximizes overall network revenue with quality of service (QoS) constraints over
both WLANs and CDMA cellular networks. WLANs operate under IEEE 802.11e medium access control (MAC) protocol, which supports
QoS for multimedia traffic. A cross-layer optimization approach is used in CDMA networks taking into account both physical
layer linear minimum mean square error (LMMSE) receivers and network layer QoS requirements. Numerical examples illustrate
that the network revenue earned in the proposed joint admission control scheme is significantly more than that when the individual
networks are optimized independently. 相似文献
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IMT—2000CDMA宏小区蜂窝无线网络的仿真 总被引:2,自引:0,他引:2
IMT-2000CDMA宏小区蜂窝无线网络的仿真,是为评估当前在第三代移动通信系统中较具实力的W-CDMA和cdma2000技术而开发的。仿真包括链路级和系统仿真两部分,主要分析研究、验证了评估了两种CDMA无线传输技术的性能以及CDMA无线网络的频谱效率/系统容量。 相似文献
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Constant S.B. Le Guennec Y. Maury G. Corrao N. Cabon B. 《Photonics Technology Letters, IEEE》2008,20(2):120-122
The purpose of this letter is to demonstrate the extension of the modulation bandwidth of a single-mode vertical-cavity surface-emitting laser (VCSEL). The aim is to reach the radio-frequency range of wireless access networks such as ultrawide-band systems with low-cost solutions. In this letter, we have studied optical microwave mixing using nonlinear direct modulation of a VCSEL. First, the nonlinear behavior of the VCSEL near the threshold has been analyzed and explained based on frequency-mixing measurements made with continuous-wave signals. Then, we have experimentally demonstrated frequency up-conversion of a quaternary phase-shift-keying signal and a wireless local area network IEEE 802.11a signal. 相似文献
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下一代网络(NGN)将融合多种异构无线接入网络。为了在满足QoS限制下,最大化网络收益,在对WLAN/CDMA等效带宽的研究基础上,提出一种基于SMDP(半马尔可夫决策规划)的最优的联合呼叫接入控制(JCAC)方案,方案考虑了WLAN和CDMA网络间的相互影响,并将网络连接的联合呼叫控制问题等效成一个半马尔可夫决策过程,仿真表明方案相对于离散时间的MDP和在MDP基础上的JCAC算法具有明显的优势。 相似文献
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Optimal Joint Session Admission Control in Integrated WLAN and CDMA Cellular Networks with Vertical Handoff 总被引:3,自引:0,他引:3
This paper considers optimizing the utilization of radio resources in a heterogeneous integrated system consisting of two different networks: a wireless local area network (WLAN) and a wideband code division multiple access (CDMA) network. We propose a joint session admission control scheme for multimedia traffic that maximizes overall network revenue with quality of service (QoS) constraints over both the WLAN and the CDMA cellular networks. The WLAN operates under the IEEE 802.11e medium access control (MAC) protocol, which supports QoS for multimedia traffic. A novel concept of effective bandwidth is used in the CDMA network to derive the unified radio resource usage, taking into account both physical layer linear minimum mean square error (LMMSE) receivers and characteristics of the packet traffic. Numerical examples illustrate that the network revenue earned in the proposed joint admission control scheme is significantly larger than that when the individual networks are optimized independently with no vertical handoff between them. The revenue gain is also significant over the scheme in which vertical handoff is supported, but admission control is not done jointly. Furthermore, we show that the optimal joint admission control policy is a randomized policy, i.e., sessions are admitted to the system with probabilities in some states 相似文献
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Yong Wang Chang-Qing Xu 《Photonics Technology Letters, IEEE》2007,19(7):495-497
Ultrafast all-optical optical time-division multiplexing demultiplexing based on the cascaded second-harmonic generation and difference-frequency generation wavelength conversion in quasi-phase-matched periodically poled lithium niobate waveguides are studied theoretically. For a typical 160- to 10-Gb/s demultiplexing process, conversion efficiency, pulse shape, time delay, phase variation, and crosstalk are investigated in two different arrangements of the 160-Gb/s signals, and both the wavelength conversion and pulse reshaping can be realized 相似文献
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Future wireless networks are expected to consist of different types of wireless networks such as code division multiple access (CDMA) networks and public wireless local area networks (WLANs). The integrated network will require vertical handoffs between different networks. In this letter, we propose vertical hard- and soft-handoff algorithms and evaluate their performance in commercial wireless networks. 相似文献
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We developed a theoretical analysis of a novel method of ultra-wideband impulse radio signals all-optical generation based on cross-phase modulation and cross-gain modulation in a nonsymmetric integrated Mach-Zehnder interferometer (MZI) containing quantum-dot semiconductor optical amplifier. The proposed method is promising due to the advantages of compact, easily controlled, and low energy integrated MZI structures as compared to optical fiber systems. 相似文献
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Demonstration of a Self-Synchronized Polyphase Sampling and Demultiplexing Scheme for Radio-Frequency Analog Signals 总被引:1,自引:0,他引:1
A novel self-synchronizing optoelectronics polyphase scheme for sampling and demultiplexing radio-frequency (RF) signals is demonstrated. One unique feature of this approach is that the optically sampled RF signal always remains in the electrical domain and thus eliminates the need for electrical-to-optical and back to electrical conversions. Furthermore, the simplicity and ease of construction of the scheme readily allows it to be scaled to obtain high sampling rates. As a proof of concept, a 100-MHz RF electrical signal sampled at the rate of 1.28 GS/s and then demultiplexed into four 320-MHz signals was experimentally demonstrated. 相似文献
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无线局域网(WLAN)是计算机网络和无线通信技术结合的产物,近几年来发展相当迅速,完全可以认为是当前产业界最为热门的技术之一。无线局域网(WLAN)已经从企业应用逐渐发展成为无线宽带接入手段。因为作为宽带接入手段的WLAN具备高带宽、扩展性好、可移动性等优点,现在运营商也将其作为一种极具潜力的业务经营;可以这样认为,较之于前几年,WLAN在安全、认证和管理性等方面有了较大的发展,可以基本满足运营商在公共场所经营的需要,也即WLAN主要用以进行局部场所的无线覆盖。但是,在WLAN用户在广域范围内漫游也较为困难,这些方面在一定程度上制约了无线局域网的发展。在WLAN发展的同时,另一种技术即CDMA1X的发展和应用也出现了很大的进展,它具备广覆盖、漫游灵活、鉴权和计费机制完善的特点,这正好可以弥补WLAN的不足,所以在应用中,可以考虑WLAN与CDMA1X的结合,并通过这种结合来发展一种灵活、方便的宽带接入方式,并通过这种宽带无线接入方式来发展各种业务,为网络增值。 相似文献
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An Uplink Short-Term Fading Prediction-Based Power Control Method for DS/CDMA Cellular Radio Systems
In previous research, a new multi-step SIR-based powercontrol, referred to as short-term fadingprediction-based (SFP-based) method, has been proposedfor DS/CDMA downlink power control. Simulation resultsshowed that the SFP method outperforms the originalmulti-step SIR-based power control. In this paper, wefurther investigate the behavior of the SFP methodapplied to uplink. Simulation results show that theSFP method still performs better than the originalmulti-step SIR-based method. Although the uplinkperformance is still poorer than the downlink usingSFP power control method instead of the originalmulti-step SIR-based method, the improvement amount ofSFP-based method compared to the multi-step SIR-basedmethod in uplink is larger than that in downlink. 相似文献
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Roelens M.A.F. Bolger J.A. Williams D. Frisken S.J. Baxter G.W. Clarke A.M. Eggleton B.J. 《Photonics Technology Letters, IEEE》2009,21(10):618-620
We present experimental results showing reconfigurable switching of four 40-Gb/s tributary channels in a 160-Gb/s data signal using Fourier-domain temporal pulse shaping and all-optical processing. Arbitrary combinations of multiple tributary channels are switched out of a high-speed data-modulated signal. The performance is characterized using a fast optical sampling oscilloscope and bit-error-rate measurements. 相似文献
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通信技术的不断发展,网络不断升级,对人类的影响也越来越大.用户能随时随地上网,不仅可以在网络上看新闻,还可以及时地处理自己的所有事务.介绍了CDMA网、WLAN以及CDMA+WLAN网的网络结构和网络的发展. 相似文献
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通过3GPP在WLAN和移动网络融合的标准情况介绍,给出了WLAN与3G网络两种融合架构,详细分析了IP地址分配、移动性管理的相关流程。 相似文献
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描述了无线资源管理中的接纳控制和功率控制。分析了接纳控制的判决依据和需要考虑的问题,介绍了功率控制的分类,并分析了开环、闭环的原理。 相似文献
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Generalized multi-protocol label switching (GMPLS) is a multipurpose control-plane paradigm that extends the MPLS scheme allowing switching without recognizing packet boundaries. In this paper, we present a novel extension that exploits a new physical layer for switching in optical GMPLS. The proposed extension is achieved through adding an optical code switching layer, or code switch capable (CSC) layer, to the existing label mapping layers. Our proposal enables finer granularity at sub-wavelength level in all-optical GMPLS core switches, resulting in significant enhancements to traffic isolation capabilities for all-optical GMPLS core switches. We employ mathematical analysis to derive performance bounds for the proposed scheme, from both the labeling capacity and network throughput points of view. We use our analytical model to derive several optimum operating points for the network, and show that our techniques significantly improve the overall performance of all-optical core networks 相似文献