The Application of NPs in WCDMA Systems

Recent efforts to add new services to the wide-band code division multiple accesses （WCDMA） system have increased interest in network processor （NP）-based routers that are easy to extend and evolve. In this paper, an application of NPs in routing engine module （REM） of radio network controller （RNC） in WCDMA system is proposed. The measuring results show that NPs have good performance and efficiency in routing traffic of the communication network and the simulation verifies the fast forwarding function of NPs.     

The Application of NTs in WCDMA Systems

Recent efforts to add new services to the wide-band code division multiple accesses (WCDMA) system have increased interest in network processor (NP)-based routers that are easy to extend and evolve. In this paper, an application of NPs in routing engine module (REM) of radio network controller (RNC) in WCDMA system is proposed. The measuring results show that NPs have good performance and efficiency in routing traffic of the communication network and the simulation verifies the fast forwarding function of NPs.     

基于时空混沌码分多址系统性能分析

将时空混沌序列应用于DS—CDMA系统，给出了系统同步模型，并对系统性能进行了分析。结果表明：用混沌序列作为地址码的CDMA系统，可以有效地抑制干扰的影响，并能提高系统的传输效率，对CDMA系统性能的改善起到重要作用。     

应用于WCDMA的双频单片SiGe BiCMOS功率放大器

采用0.18μm SiGe BiCMOS工艺设计实现了一款用于3GPP WCDMA 850/2100(band-I/band-V)的双频单芯片功率放大器(PA)。PA采用单端共射级3级级联的结构,具有带模拟开关的片上偏置电路,通过控制偏置电流对两个PA工作状态进行切换。制造的芯片面积为1.82 mm×2.83 mm,片上集成了开关电路、偏置电路和输入匹配、级间匹配电路。在3.3 V电源电压下测试结果表明,对于band-V(CLR)频段,PA的线性输出功率P1 dB为28.6 dBm,5 dBm输入时,功率附加效率PAE,为34%。对于band-I(IMT)频段,PA的P1 dB为26.3 dBm,PAE为31%。     

Highly Linear and Efficient Microwave GaN HEMT Doherty Amplifier for WCDMA

A highly linear and efficient GaN HEMT Doherty amplifier for wideband code division multiple access (WCDMA) repeaters is presented. For better performance, the adaptive gate bias control of the peaking amplifier using the power tracking circuit and the shunt capacitors is employed. The measured one‐carrier WCDMA results show an adjacent channel leakage ratio of ?43.2 dBc at ±2.5‐MHz offset with a power added efficiency of 40.1% at an average output power of 37 dBm, which is a 7.5 dB back‐off power from the saturated output power.     

一种新的光码分多址网络地址码分配策略及其性能分析

本文提出了一种新的适用于OCDMA网络的地址码分配策略,并采用新的数学模型——处理器共享系统,对OCDMA网络的稳态吞吐率和平均时延进行了仿真计算,结果表明,本文提出的分配策略的性能优于目前文献中已报道的策略;采用处理机共享系统模型的仿真结果与实际情况非常吻合,它比传统的马尔可夫链模型简单,适合用于对OCDMA接入网进行建模.     

Adjacent channel interference in a macrocell/microcell WCDMA system

This paper studies the impacts of adjacent channel interference (ACI) on uplink capacity in a multi‐macrocell/multi‐microcell wideband code‐division multiple access (WCDMA) system. A method is presented for computing ACI and deriving capacity limitation. This method is based on an interference analysis that accounts for shadow fading, and random distribution of mobile users. The results indicate that both the base station (BS) separation and adjacent channel interference power ratio (ACIR) strongly affect system capacity reduction. The proposed method in this paper is useful for measuring the impacts of ACI on uplink capacity. Copyright © 2008 John Wiley & Sons, Ltd.     

线性Doherty功放的优化设计

设计了一个高效率、高线性度的射频Doherty GSM基站功放。利用Doherty功放的载波放大器与峰值放大器之间的互调对消技术使Doherty功放的三阶互调干扰(IMD3)改善了11dBc;并通过相位补偿延迟线的前置处理进一步提高了功放的效率,使其效率比常用的平衡补偿线方案提高了4%左右。文中利用两个MRF9060功放管制作了一个GSM频段Doherty功放,其实测1dB压缩点功率(P1dB)达到了130W;双音测试表明:经过4.5dB的回退后三阶互调失真(IMD3)优于-35dBc,此时功率附加效率(PAE)高达47.3%;WCDMA 3GPP的测试结果表明:经过6dB回退后,其5MHz偏移量的邻道功率比(ACPR)优于-40.5dBc,PAE为43.5%,比AB类平衡功放的效率提高了17.8%。结果表明:该设计方案较好地解决了射频功放功率与效率之间的矛盾,适用于射频功放的设计。     

An adaptive digital predistortion for compensating nonlinear distortions in RF power amplifier with memory effects

In this paper, an adaptive digital predistortion based on a memory polynomial model is proposed in order to linearize the power amplifier with memory effect. The coefficients of the power amplifier model have been extracted using a least square method and those of predistortion have been identified by applying an indirect learning structure. Finally, the performance of digital predistortion has been demonstrated using the simulation of the power amplifier and the digital predistortion excited by a modulated 16 QAM signal in Matlab software. According to the simulation results, the criterion of adjacent channel power ratio (ACPR) declined by around 15 dB and the input/output power spectrum density of the power amplifier has quite similar curves. The linearized power amplifier output spectrum demonstrates the superiority of the proposed predistorter in eliminating the spectral regrowth which is caused by the memory effect in comparison to the other linearization methods.     

一种WCDMA系统下行信道频偏估计算法及其性能分析

文章在深入研究WCDMA下行链路的信道结构及接收信号处理流程基础上,提出了一种在Rake接收机中,通过对P-CPICH（主公共导频信道）序列两次相关检测实现频偏估计的算法;同时,对该算法主要性能指标进行了分析及仿真,验证了算法的可行性。     

基于TD-SCDMA无线定位MUSIC算法及其性能的研究

为了实现基于TD-SCDMA智能天线圆-角定位,针对我国TD-SCDMA采用的是非Vandermonde结构的8阵元均匀圆阵智能天线,不能直接采用MUSIC算法对移动台的来波方向(DOA)进行估计的特点,对基于TD-SCDMA智能天线进行了预处理,使MUSIC算法能够用于基于TD-SCDMA智能天线的DOA估计,同时考虑到实际应用分别对理想智能天线和非理想智能天线的MUSIC算法的性能进行了分析。     

基于离散正弦变换的单载波频分多址系统及其性能分析

为分析离散傅里叶变换(DFT)与离散正弦变换(DST)对单载波频分多址(SC-FDMA)系统某些性能的影响,提出了一种基于离散正弦变换的单载波频分多址系统。给出了基于DST的SC-FD-MA系统的结构框图,接着重点推导和分析了DST IFDMA和DSTLFDMA信号的时域表达式,最后讨论了系统的峰值平均功率比(PAPR)和不同脉冲成形滤波器的冲激响应。仿真结果表明,基于DST的SC-FDMA系统比传统的基于DFT的SC-FDMA系统和正交频分多址接入(OFDMA)系统有更好的比特误码率。此外,DST SC-FDMA信号的PAPR性能接近于DFT SC-FDMA且优于OFDMA。     

基于复小波包的MC-CDMA系统及上行链路性能分析

文章在分析多载波扩频码分多址的基础上，利用优化生成的复小波包及变换，研究了一种基于复小波包的多载波CDMA系统在多径瑞利衰落环境下的上行链路性能。仿真结果表明该系统要优于通常的MC-CDMA系统和基于实小波包变换的MC-CDMA系统，具有良好的抗衰落能力。并采用多天线分集接收技术进一步完善系统性能，从而增强了系统抗多径干扰和多址干扰的能力，且得到了更低的误码率。     

基于OOC的WDM+OCDMA系统性能研究

基于光正交码,研究了WDM+OCDMA系统的性能。采用4个波长信道和3个码字的光正交码OOC(37,4,1),对12个用户的WDMA+OCDMA进行了系统仿真,用户数据速率为1Gbit/s,单模光纤长为50km,色散补偿光纤长为5km。如需增加WDMA+OCDMA的用户数,可以通过增加波长信道数或码字容量来实现。分析了色散效应对WDMA+OCDMA系统性能的影响,研究了用户之间相对延时对多址干扰和系统性能的影响。     

基于C-RAN与LTE-Hi的BR-OFDMA导频图案设计

在集中式/协作式/云计算无线接入网(C-RAN)环境下,结合热点及室内覆盖的长期演进(LTE-Hi)特点,研究导频图案的设计。LTE-Hi要求插入的导频数量比传统的长期演进(LTE)少,又由于其覆盖特点导致小区边界更容易受相邻小区干扰,由此提出一种应用块重复的正交频分多址(BR-OFDMA)和压缩感知信道估计技术的导频图案设计方案。该方案能够探测各相邻小区间的干扰情况,然后根据干扰情况设置BR-OFDMA参数,最后得到导频图案。该方案能明显减少导频数量,在C-RAN的云结构下更适合LTE-Hi相邻小区间的协作配置,能根据干扰情况,在资源消耗与性能之间进行平衡。仿真表明该方案在低信干比环境下仍能表现较好性能,适合在C-RAN与LTE-Hi中应用。     

Analysis of Sub-Carrier Multiplexed Radio Over Fiber Link for the Simultaneous Support of WLAN and WCDMA Systems

The present third generation (3G) wireless technology can provide data oriented applications. However, the bit rate is limited to around 2 Mbps with limited mobility. Today, more applications demand high data rate and reasonable mobility. Therefore, by integrating 3G cellular system and wireless local area network (WLAN), there is a potential to push the data rate higher. This integration means 3G cellular users can enjoy high data rate at a location that is within WLAN coverage area. Similarly, WLAN users also can have data services as long as they are under the coverage of the 3G cellular system. The 3G cellular system has a much larger coverage than the WLAN. In this paper, we present the first step toward an integration of the two systems. This paper presents a fiber-wireless architecture that simultaneously supports the wideband code division multiple access (WCDMA) system and the IEEE 802.11b WLAN. Our approach uses sub-carrier multiplexed (SCM) architecture to combine and transmit 2.4 GHz WLAN and 1.9 GHz WCDMA signals through an optical fiber from a central base station (CBS) to a radio access point (RAP, single antenna unit). After the fiber, the signals continue to propagate through the air interface to respective mobile stations. The WLAN access point is also located at the CBS. For the SCM architecture, we investigate three areas: i) the signal to noise ratio of the uplink and the downlink, ii) the cell coverage area for the WCDMA and WLAN systems, and iii) the throughput of the IEEE 802.11b WLAN. Our results show that with up to 2.5 km cell radius, better than 18 dB SNR is possible with 5 km fiber link for WLAN system. Simultaneously, the WCDMA system has at least 18 dB SNR for a cell coverage radius of 8 km. These numbers depend on the relative RF power of each system in the fiber.Roland M.C. Yuen received a Bachelor of Electrical Engineering degree in 2003 from Ryerson University, Toronto, Canada. He is pursuing a Master of Applied Science degree at Ryerson University. He has a conference paper. His research interests are in the area of optical and wireless communications.Currently, he works on unique fiber based architecture to extend the capability of cellular networks and support wireless LANs simultaneously.Xavier N. Fernando () obtained B.Sc. Eng. (First Class Honors) degree from Sri Lanka, where he was first out of 250 students. He got Master’s degree from the Asian Institute of Technology (Bangkok) Ph.D. from the University of Calgary, Canada in affiliation with TRLabs. He has worked for AT&T for three years as an R&D Engineer. Currently he is an Assistant Professor at Ryerson University, Toronto, Canada.Dr. Fernando one US patent and about 38 peer reviewed publications in journals and conference proceedings. His research focuses on signal processing for cost-effective broadband multimedia delivery via optical wireless networks. Dr. Fernando′s work won the best research paper award in the Canadian Conference of Electrical and Computer Engineering for the year 2001. His student projects won both the first and second prize at Opto Canada – the SPIE regional conference in Ottawa in 2002. He is a senior member of IEEE, member of SPIE, Chair of the IEEE Communications Society Toronto Chapter and licensed Professional Engineer in Ontario, Canada. He has many research grants including Canadian Foundation of Innovations (CFI), Ontario Innovations Trust (OIT) and Natural Sciences and Engineering Research Council (NSERC) of Canada.     

相关衰落信道上WCDMA系统的安全性能分析

对多输入多输出（MIMO）相关衰落信道上宽带码分多址接入（WCDMA）的安全性能进行评估,一种省时高效的解决方案是理论分析法。推导了相关 Nakagami 衰落信道上采用空时分组码和二维瑞克接收机（2D-Rake）的 WCDMA 系统的非零安全容量概率和安全中断概率的精确解析表达式。利用上述表达式,可以快速地评估收发天线数、天线相关系数、Nakagami衰落系数、平均路径衰减系数等参数对WCDMA系统安全性能造成的影响。数值计算和仿真结果相吻合,证明了以上理论分析的正确性。推导了WCDMA系统渐近安全中断概率的解析表达式。结果表明,WCDMA 系统的安全分集增益为主信道各个可分离路径上的分集增益之和,与窃听信道无关;对于恒定多径强度轮廓的同分布Nakagami衰落信道,WCDMA系统的安全分集增益为主信道的收/发天线数、多径个数以及Nakagami衰落系数四者之积。     

无线接入网中两种关键技术:OFDM与CDMA的比较分析

介绍了无线接入网中的两种关键技术，OFDM（正交频分复用）和CDMA（码分多址），从调制技术，抗干扰能力，功率控制、网络规划，峰均功率比和均衡技术等方面全面系统地比较分析了OFDM和CDMA各自的优缺点，结果证明了OFDM技术的先进性及其令人瞩目的应用前景。     

OCDMA系统中新型正交码的设计及性能研究

为了得到性能较为良好的正交码,采用没有重复数字的全间隔集,进行了地址码的设计和系统仿真验证,设计出的正交码具有理想的相关性和灵活的码字容量。分析整个系统,在考虑各种噪声和多址干扰的影响下,推导出正交码的误比特率公式。自行设计并搭建了采用光纤延时线作为编解码器的异步光码多分址系统。结果表明,该正交码能够适应更多用户的需求,通过误比特率公式计算和系统仿真得到的结果都较为理想,此研究对需要大容量的光码多分址系统的进一步发展具有一定的帮助。     

星间无线OCDMA系统单用户检测容量研究

提出了一种新颖的异步光码分多址(OCDMA)系统,结果表明,在理论信息容量限为1bit·chip条件下,单用户检测下OCDMA系统的容量随着用户数的增加有所下降,但在用户数较多时基本保持在0.75bit/chip的水平;单用户检测下系统的最大容量限不在信号输入概率为0.50时出现;在用户数较少时,信号输入概率偏离0.50越大,系统最大容量限越低。由此推证了异步OCDMA系统在单用户检测下的理论信息容量限。