Intelligent antenna system for cdma2000

Third-generation (3G) cellular code division multiple access (CDMA,) systems can provide an increase in capacity for system operators over existing second-generation (CDMA) systems. The gain in capacity for the base station to mobile (forward) link can be attributed to improvements in coding techniques, fast power control, and transmit diversity techniques. Additional gains in the mobile to base station (reverse) link can be attributed to the use of coherent quadrature phase shift keyed (QPSK) modulation and better coding techniques. While these enhancements can improve the performance of the system, system operators expect that with increased demand for data services, even greater capacity enhancements may be desired. There are essentially three methods, which we describe, based on diversity, spatial beamforming, and a combination of diversity and beamforming, to improve the performance of system through the use of additional antennas at the base station transmitter and receiver. The performance improvements are a function of the antenna spacings and the algorithms used to weight the antenna signals. We focus on the possibilities for the cdma2000 3G system that do not require standards changes. We highlight the performance enhancements that can be obtained on both the reverse and forward links through use of an antenna array architecture that supports a combination of beamforming and transmit diversity. We focus on the performance enhancements for the forward link     

Interference analysis and capacity for forward link 3G CDMA network with adaptive antennas

In code division multiple access (CDMA) systems, the capacity of forward link (FL) communication to mobile receivers is limited primarily by co‐channel interference (CCI). Adaptive antenna arrays (AAAs) that use antenna arrays along with advanced signal processing at the base station (BS) have been proposed to mitigate this limitation. For a 3G CDMA cellular network, where each BS equipped with an AAA serves mixture of voice and data users within its coverage, we study FL capacity and investigate the effects of different factors (array topology, multipath angle spread, data rate, and beamforming algorithm) on this capacity under Rayleigh fading channel. By modeling the instantaneous signal‐to‐interference power ratio received at the mobile, we derive the system outage equation that considers blocking of either desired voice or data user. Simulation results show that for the same element spacing and number of antenna elements per cell, the uniform circular array (UCA) topology results in larger capacity than the sectorized uniform linear array (ULA) topology does, and that a larger angle spread or data user rate reduces FL capacity. Copyright © 2007 John Wiley & Sons, Ltd.     

Reverse high-speed packet data physical layer enhancements in cdma2000 1/spl times/EV-DV

The rapid growth of Internet-based applications calls for design of a high-speed wireless packet data communication system. This anticipated increase in future mobile wireless packet data services has challenged the current 3G standardization bodies to respond with evolved 3G system specifications capable of providing increased data throughput. In response to such a need, 3GPP2 recently completed the enhanced reverse link standardization effort of the CDMA technology flagship, cdma2000/spl reg/ by completing the definition of the 1/spl times/EV-DV 1/spl times/ system. 1/spl times/EV-DV achieves higher data throughput while simultaneously providing coexisting and backward-compatible voice services within the same spectrum. This feature of 1/spl times/EV-DV allows wireless operators to manage the voice and data loading in their system more efficiently. This article describes the physical layer reverse link enhancements in cdma2000 revision D that are necessary to support 1/spl times/EV-DV.     

An overview of CDMA evolution toward wideband CDMA

Third-generation mobile radio networks, often dubbed as 3G, have been under intense research and discussion recently and will emerge around the year 2000. In the International Telecommunications Union (ITU), third generation networks are called International Mobile Telecommunications-2000 (IMT-2000), and in Europe, Universal Mobile Telecommunications System (UMTS). IMT-2000 will provide a multitude of services, especially multimedia and high-bit-rate packet data. Wideband code division multiple access (CDMA) has emerged as the mainstream air interface solution for the third-generation networks. In Europe, Japan, Korea, and the United States, wideband CDMA systems are currently being standarized. This article provides a comprehensive introduction to wideband CDMA. It also provides a review of the wideband CDMA air interface proposals including WCDMA in Europe and Japan, cdma2000 in the United States, and wideband CDMA in Korea.     

cdma2000 1X网络混合业务环境下载波配置方法的探讨

介绍了cdma2000 1X语音、数据业务对资源的占用情况,引入了最大平均吞吐量的概念来衡量载波的处理能力,总结了一套关于cdma2000 1X混合业务网络资源配置的方法。     

cdma2000 1xEV-DO系统的QoS保证机制

cdma2000 1xEV-DO最突出的业务特征是能够提供丰富的多媒体业务，可以使用现有频谱并和IS-95或cdma2000 1x混合组网分别传递数据业务和语音业务，本文从系统对多媒体业务的支持和无线资源管理两方面出发，对1xEV-DO系统无线数据业务的QoS保证机制进行了研究和探讨。     

Evolution of wireless data services: IS-95 to cdma2000

Existing IS-95-based CDMA systems support circuit-mode and packet-mode data services at a data rate limited to 9.6-14.4 kb/s. Fueled by the explosive growth of the Internet, applications and market opportunities are demanding that higher capacity, higher data rates, and advanced multimedia services be supported in the near future. The evolution of the IS-95 CDMA standard to higher data rates and more advanced services occurs in two steps. The first step, IS-95-B, is an enhancement to the IS-95-A standard and offers the highest possible performance without breaking current IS-95-A air interface design characteristics, thereby maintaining strict compatibility with existing base station hardware. The proposed standard will support a high data rate (64 kb/s) in both directions, to and from the mobile device. A new burst mode packet data service is defined to allow better interference management and capacity utilization. The second evolution step, cdma2000, provides next-generation capacity, data rates, and services. The cdma2000 system includes a greatly enhanced air interface supporting CDMA over wider bandwidths for improved capacity and higher data rates while also maintaining backward compatibility with existing IS-95 CDMA end-user devices. The cdma2000 system also includes a sophisticated MAC feature to effectively support very-high-data-rate services (up to 2 Mb/s) and multiple concurrent data and voice services. This article describes the design and performance of the high-data-rate service provided by second- and third-generation CDMA systems     

An analytical model for reverse data channel scheduling techniques in cdma2000 1xEV‐DO

Efficient utilization of bandwidth and high data rates have a great impact on the performance of wireless networks. The cdma2000 1xEV‐DO standard provides high‐speed wireless data services to mobile subscribers based on CDMA technology. In this paper, we study the bandwidth utilization for the 1xEV‐DO packet mode standard. In particular, we develop an analytical model for lowest‐rate‐first, highest‐rate‐first priority scheduling techniques, and two round‐robin fair scheduling techniques over the reverse data channel in cdma2000 1xEV‐DO. For these four scheduling techniques, the distribution of the mobile stations (MSs) among the possible data rates is modeled as a Markov process. An analytical expression for the steady state system throughput is derived from the steady state distribution of the above Markov process. The developed model is validated through simulations. Copyright © 2008 John Wiley & Sons, Ltd.     

Performance of Broadcast and Multicast Service with Interference Cancellation Based on Macro Diversity

The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services(BCMCS) to meet an increasing demand for multimedia data services.Single frequency network(SFN) is recognized as an effective way to improve the spectral efficiency of the BCMCS system.To improve the coverage and the data rate of the BCMCS users,an interference cancellation algorithm based on macro diversity is introduced in this paper.The performance of BCMCS in CDMA2000 EV-DO networks under the condition of SFN is evaluated.The simulation results show a significant improvement in bit error ratio(BER) while quantitatively validating the efficiency of our approach.     

IS-95与CDMA2000技术的发展

目前,CDMA在成为第三代通信系统最主要的无线接入技术后,技术上出现了突习猛进,本文对现有的CDMA技术IS－95与CDMA2000技术作出比较,简要地介绍了CDMA2000的技术特点和其向3G平滑过度的演进过程,进一步探讨IS－95和CDMA2000在今后的发展趋势。     

3G标准选择研究

3G的主导业务应该是移动因特网业务,它的下行容量应该数倍于上行容量.但早期的3G标准都是上下行信道容量基本对称的系统,存在严重技术缺陷.cdma2000标准已做出重大改进,抛弃了cdma2000 3x标准和CDMA方式,转向时分多址的EV-DO方式.然而WCDMA和TD-SCDMA标准并未做出相应改动.TD-SCDMA标准的多项参数说明它适用于步行移动通信系统,依靠智能天线技术很难改变该标准的基本特征.     

Successive beamforming,multiuser detection and diversity reception for multicarrier DS-CDMA system with antenna array

Code-Division Multiple-Access (CDMA) systems are interference limited,and therefore efficient interference management is necessary to enhance the performance of a CDMA system.In this paper,a successive beamforming (spatial filtering),linear decorrelating MultiUser Detection (MUD, temporal filtering) and diversity reception structure for uplink multicarrier Direct Sequence CDMA (DS-CDMA) system with antenna array are proposed.By beamforming,the antenna array suppresses interference according to the distinct array signature.Subsequently,linear decorrelating MUD is ap- plied to separate the signals of different users and eliminate Multiple Access Interference (MAI).Finally, the decorrelated signals at different subcarriers that belong to the same user are combined to achieve frequency diversity.Simulation results show that the proposed structure offers significant Bit Error Rate (BER) performance improvement by successively exploiting the space-time-frequency processing.     

A novel adaptive beamforming algorithm for antenna array CDMA systems with strong interferers

Blind beamforming based on the maximum signal-to-noise ratio (MSNR) can improve the performance of an array system only when the processing gain of the given code-division multiple-access (CDMA) system is high enough such that the desired signal can become dominant after despreading (see Choi, S. and Shim, D., IEEE Trans. Veh. Technol., vol.49, p.1793-1806, 2000; Choi, S. and Yun, D., IEEE Trans. Antennas Propagat., vol.45, p.1393-1404, 1997). We consider a maximum signal-to-interference-plus-noise ratio (MSINR) beamforming. The MSINR performance criterion is chosen to deal with strong interferers effectively. It is shown that blind MSINR beamforming is possible by directly utilizing the input and output signals of correlators of the CDMA systems. In addition, we propose an adaptive beamforming algorithm at a lower computational complexity - about O(7.5N) - where N is the number of antenna elements of the array system. Simulation results are presented in various signal environments to show the performance of the proposed adaptive algorithm.     

On generalized optimal scheduling of high data-rate bursts in CDMA systems

In a code-division multiple access (CDMA)-based wireless communication system, forward link is power limited and reverse link is interference limited. With power control and statistical multiplexing, voice services can be supported reasonably well. However, for high data-rate services, a more comprehensive scheduling mechanism is needed in order to achieve a high capacity while satisfying the forward and reverse link constraints. We formulate the high data-burst scheduling as a integer programming problem using a generic CDMA system model. We also suggest an optimal algorithm for generating scheduling solutions. With cdma2000 system details plugged in the proposed algorithm, it is found that our algorithm considerably outperforms several fast heuristics, including equal sharing, first-come-first-served, longest delay first, and shortest burst first.     

从CDMA到LTE的移动网络技术演进

本文讨论了CDMA向LTE演进过程中各项技术的主要特性,重点分析了cdma2000 1x EV-DOA、cdma2000 1x EV-DO增强型、calma2000 1x EV-DOB以及LTE等技术.在此基础上,提出了网络演进中各项技术所需要关注的主要问题.为CDMA技术的发展和网络演进提供了参考意见.     

3G wireless and cdma2000 1/spl times/ evolution in Korea

The cdma2000/spl reg/ I/spl times/EV-DV system is designed to meet the ever-increasing demand for high-speed packet data transmission while providing the same level of revenue generated by conventional voice communications on existing cdma2000 1/spl times/ systems. It supports concurrent voice and high-speed data on a single cdma 1.25 MHz carrier, and offers improved flexibility for operators to manage data and voice services cost efficiently. However, the Korean market has proved that providing higher bandwidth to the user does not guarantee the success of mobile data service. Users tend not to use expensive mobile wireless data services such as video streaming, video on demand, and MP3 music download service that they feel do not provide enough justification for their costs. The problem LG Telecom faces now as a mobile operator is not only to evolve technologies that enable various services, but also to find a way to provide attractive services at reasonable prices. This article describes experiences in the wireless data market in Korea as well as the market needs and driving forces for cdma2000 1/spl times/EV-DV developments.     

柳州电信cdma2000网络室分小区PN优化研究

近年来,中国电信在原中国联通CDMA网络基础上进行了大规模的网络升级和扩容,将CDMA 1x网络升级至cdma2000。在覆盖建设已基本完成的情况下,用户集中区域的室分网络建设和优化逐渐成为CDMA网络发展重点。其中,PN规划对cdma2000网络质量影响重大,是cdma2000网络优化中必不可少的一部分。本文基于以上背景,结合柳州cdma2000网络现状,分析和研究了现有cdma2000网络室分小区PN方案中PN资源紧张、同PN-Offset和邻PN-Offset干扰等问题,提出了一种PN规划优化方案,以减弱网络信号干扰、提高通信质量、打造高品质3G网络。     

基于自适应拟牛顿法的CDMA天线阵列波束形成

针对于CDMA系统自适应天线阵列,提出了一种新的盲自适应MSINR(Maximum Signal-to-Interference plus noise ratio)波束形成算法.首先,将MSINR准则转化为一种新的无约束损失函数,并且从理论上分析该损失函数的性质.然后,应用自适应拟牛顿方法得到在线迭代波束形成算法.该算法无需训练序,而是利用CDMA信号自身的结构特点,结合空间处理提高了系统性能.最后,给出了仿真结果,表明算法具有较快的收敛速度和良好的动态跟踪能力.     

软切换对cdma2000 1x数据业务的影响及优化策略

降低软切换比例在目前CDMA网络中具有重要的意义和紧迫性,本文通过分析CDMA软切换对系统资源占用及对cdma2000 1x数据业务性能的影响,提出降低软切换的几种方法。实际案例说明,降低软切换比例在CDMA网络中取得了容量和质量的明显提高。     

CMA自适应阵列在CDMA通信系统的应用

由于CDMA(Code Division Multiple Access)通信系统实施了功率控制，在基带不能直接用CMA进行自适应阵列的波束形成．通过分析CDMA系统的特点，我们提出在接收信号解扩后再应用CMA进行波束形成．这种新的波束形成方法不仅为CMA自适应阵列在CDMA系统中的应用提供了一种途径，而且还能防止CMA收敛到错误信号上，从而提高系统的可靠性．仿真结果表明，与全向天线系统相比，采用CMA自适应阵列的系统性能有了很大的改善，系统的容量得到成倍的增加．在强干扰情况下，虽然CMA的干扰方向信号抑制效应变弱，但其性能改善仍然十分明显．