CDMA蜂窝网中的无线资源管理

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。     

面向CDMA蜂窝网的无线定位技术

蜂窝通信系统中移动台定位问题作为研究的热点之一,受到了广泛的关注.实现蜂窝通信系统中移动台定位,需要解决定位算法与定位参数估计问题.本文以定位算法与定位参数估计为主线,综述了蜂窝通信系统中移动台定位的发展过程、现状、取得的进展以及面临的挑战,特别是对减轻非视距传播影响的定位算法进行了详细讨论.     

Efficient Radio Resource Management in Integrated WLAN/CDMA Mobile Networks

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.     

IMT—2000CDMA宏小区蜂窝无线网络的仿真

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。     

天线阵CDMA蜂窝无线通信系统的空时处理

本文围绕天线阵ＣＤＭＡ蜂容无线通信系统,简介了无线信道、单时间与单空间处理的特点,综述了空时自理即矢量均衡技术,包括系统模型与空时过取样信号的结构特性以基于某些优化准则和结构特性的空时处理方法,论证了将空时处理嵌入ＩＭＴ－２０００的可行性。     

Low-Cost All-Optical Up-Conversion of Digital Radio Signals Using a Directly Modulated 1550-nm Emitting VCSEL

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.     

基于半马尔可夫链的WLAN/CDMA联合呼叫接入控制

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。     

Optimal Joint Session Admission Control in Integrated WLAN and CDMA Cellular Networks with Vertical Handoff

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     

认知无线电与WLAN的融合技术

随着无线局域网(WLAN)的迅速普及,有限的可用频谱资源日益紧张。认知无线电(CR)技术具有动态重用空闲频谱资源的能力,可以有效提高频谱利用率,得到了无线通信行业的关注。通过将CR技术与无线局域网相融合,可以为无线局域网提供更为灵活的通信,扩展无线局域网的工作频段。IEEE 802.11y无线局域网标准的制定进一步推动了CR技术的应用。CR技术与无线局域网融合的过程中,还需要完善包括频谱感知、频谱资源共享和分配、动态频率选择和传输功率控制等技术。     

Analysis of Ultrafast All-Optical OTDM Demultiplexing Based on Cascaded Wavelength Conversion in PPLN Waveguides

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     

Vertical handoff in integrated CDMA and WLAN systems

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.     

Proposal for All-Optical Generation of Ultra-Wideband Impulse Radio Signals in Mach–Zehnder Interferometer With Quantum-Dot Optical Amplifier

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.     

Demonstration of a Self-Synchronized Polyphase Sampling and Demultiplexing Scheme for Radio-Frequency Analog Signals

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.     

WLAN与CDMA1X网络融合方案

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。     

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.     

Flexible and Reconfigurable Time-Domain Demultiplexing of Optical Signals at 160 Gb/s

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.     

浅谈CDMA+WLAN网络的结构和发展

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.     

无线局域网和蜂窝移动网络融合技术研究

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。     

CDMA系统中的无线资源管理

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。     

Optical CDMA for All-Optical Sub-Wavelength Switching in Core GMPLS Networks

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