GPON系统带宽利用率的研究

文章在深入分析吉比特无源光网络(GPON)上下行帧结构的基础上,找出了影响其上下行带宽利用率的各个因素,并逐一进行了量化分析,给出了计算上下行带宽利用率的表达式,并且计算出了GPON上下行带宽利用率的变化范围.最后,对比了GPON和以太网无源光网络(EPON)的带宽利用率和成本,结果表明GPON具有更高的效能成本比.     

xPON技术应用探讨

在电信网、计算机网和有线电视网三大网络融合的背景下,xPON技术由于其投资少建效快,适应全业务接入的要求,目前已经广泛应用于通信传输领域。文章介绍了xPON技术产生的背景、技术原理,分析了几类主要的应用场景,并结合xPON技术的发展情况,提出了网络演进的策略与建议。     

EPON系统中ONU端口环路检测方案及实现

在以太网无源光网络(EPON)系统中,光网络单元(ONU)用户端口成环将会造成同一个无源光网络口下所有的业务中断。首先分析了EPON系统中ONU侧用户端口可能造成环路的主要原因及危害;然后提出了分别在OLT侧和ONU侧构造特殊报文进行环路检测的方案,并简要比较了它们的优缺点;最后对OLT侧环路检测方案的设计实现进行了重点描述。实践证明,采用OLT侧特殊报文检测方案能够有效地发现和防止ONU侧用户端口环路。     

GPON技术在世博园区的应用探讨

介绍了吉比特无源光网络（GPOH的体系结构和标准化情况,在此基础上结合世博移动项目情况,从世博园区的需求、园区内应用场景、OLT和ONU的部署、ODN线路设计等多个角度,对上海移动世博项目的GPON综合接入FTTx解决方案进行了有益探讨。通过此次世博园区GPON的部署,可以树立样板工程,创造新的业务收入来源,并为后续规模部署积累从建设到运维等方面经验。     

FTTH--下一代宽带接入技术

回顾了近期FTTH在国际国内发展的状况,讨论了实现FTTH的各种解决方案,归纳了FTTH实施过程中的一些经验教训,指出了FTTH是接入网发展的必然进程.     

三网融合及其相关宽带接入技术的研究

详细介绍了“三网融合”的概念及其所具有的特征，并指出其是未来网络发展的趋势所在，并对目前三种实际解决方案进行了全面的对比论述。本文首先提出了一种基于CableModem技术在HFC网络中实现关于电信、计算机和有线网三网合一的方案，然后从技术以及带宽的角度阐述了另外一种更为理想的基于FTTH的最终实现方案，最后基于现实条件提出了一种利用FTTC＋HFC实现全业务接入的解决方案，以达到促使HFC向FTTH转化的目的。     

GPON系统OLT接收侧FEC解码电路的设计

前向纠错(FEC)在通信系统中有着广泛的应用.在吉比特无源光网络(GPON)系统中,上行带宽是以动态方式进行分配的,光线路终端(OLT)接收侧要求能够支持RS(255,239)及其缩短码的解码.文章采用一种"变换时钟域+RS全码解码"的方法,通过基于双端口随机存储器(DPRAM)的时钟域变换后,再进行RS全码解码.采用这种方式能够以较低的硬件复杂度完成FEC解码.     

光纤接入及FTTH技术与应用分析

宽带光纤接入及FTTH具有传输容量大、传输距离远、传输质量高、可扩展性好、运维成本低、抗干扰和保密性强等优点,是宽带接入的最终发展方向,正成为国内外电信运营商关注的重点。本文从分析国内“十一五”期间宽带业务及带宽需求出发,详细介绍了与FTTH相关技术的特点及最新进展,分析了基于PON技术的FTTx的应用场景,最后给出了综合的FTTx应用建议。     

FTTx无源光网络路在何方

这里分析了主流的光纤到户（FTTH）和光纤到楼（FTTB）两种光纤接入模式的网络结构及模型的基础上,详细论述比较了以太网无源光网络（EPON）和吉比特的无源光网络（GPON）接入技术性能,对10G以太网无源光网络（10G EPON）、波分复用无源光网络（WDM-PON）、长距离无源光网络（LR-PON）等无源光网络（xPON）新技术进行了分析研究,提出了FTTB接入模式的网络改造以及吉比特的无源光网络（EPON）向10G以太网无源光网络（10G EPON）平滑演进的发展方向和具体的解决方案。     

PON在商业用户业务接入中的应用

在业务、组网成本、技术、竞争等多方面驱动下,光纤直接接入商业用户并提供综合业务接入成为接入网发展的方向.PON作为一种新兴技术,具有高带宽、节省远端有源机房、便于维护、业务部署迅速等特点,将在商业用户的接入方案中得到广泛应用.     

Multiple-access capacity in mobile user satellite systems

The channel capacity of a satellite direct sequence CDMA system is analyzed including the effects of faded user interference, overlapping antenna beams, imperfect equalization of the antenna pattern across an antenna cell, and diversity reception. Simplified models are used to describe the impact of these effects on the channel capacity of single and multiple cofrequency CDMA systems. In a comparison of the uplink and downlink paths, the uplink of the CDMA system is shown to limit the channel capacity because the downlink can utilize code-orthogonality and coherent demodulation. In a multiple system comparison between band-shared CDMA and band-segmented FDMA/TDMA technologies, FDMA/TDMA is shown to provide about the same capacity for uniformly distributed traffic conditions over many cells and dramatically better capacity when traffic is concentrated in one cell. Due to the peak nature of telephony, this result supports the use of band-segmented systems in mobile user satellite systems     

xPON系统长发光ONU检测定位解决方案

基于光功率检测和功率叠加原理,以及当前的xPON部署应用情况,提出了一种实用性、可靠性强的长发光ONU快速检测、定位和隔离的解决方案.经过规模应用的验证,该方案可行有效.     

Efficient E-coupon systems with strong user privacy

We propose two novel e-coupon systems that can achieve the following new properties: (1) The coupon issuer (or service provider) can trace the identity of a dishonest user while the identity privacy (or anonymity) of a honest user is still well protected. (2) A honest user’s redemption privacy (i.e., the items chosen when redeeming an e-coupon) is well protected from the service provider. (3) If a dishonest user redeems an e-coupon for more than the pre-determined number of times, then the user will lose the redemption privacy (i.e., all the choices the user has made in the previous redemptions can be revealed). We first propose a novel blind signature scheme that we employ together with oblivious transfer to construct our first e-coupon system, which achieves the first two properties without the involvement of any trusted third party. Then we propose a novel oblivious transfer scheme and use it to construct the second e-coupon system that can achieve all the properties given above. We also define the formal security models for these new security requirements, and show that our new e-coupon systems are proven secure in the proposed models.     

便携系统的用户接口设计

有许多方法从一个计算机平台输入或输出信息。在大多数情况下是由应用来决定什么是最适合的用户接口方式。选择的范围可以是标准键盘或小型键盘、光笔、触摸屏,甚至是语音输入。还包括和机器集成在一起的点击式输入设备,如触摸垫（touch pad）、小型鼠标、点击棒（pointing stick）等。将来,也许会有其他更有趣的设备。决定选择这些方法的主要因素是成本和接口的方式。如果成本不是一个主要考虑的因素,那么,几乎所有的接口方式都可以被选用。语音识别应该是最难实现的一种输入方式,但如果不考虑成本,则可以极大地提高处理器的处理能…     

Advanced on-board processing for user oriented communication systems

The continuing improvement of RF components, particularly in the field of spot-beam antennas, combined with the steady progress in digital technology, leads us to consider the advantages of a satellite system able to provide full connectivity to ground stations operating at different data rates. For low data rates, two different access methods: continuous TDM and Multi-carrier TDMA, are compared for earth-stations operating at 2Mb/s. The two methods are compared from the point of view of efficiency and adaptability in a non-uniform load environment. Some control criteria are proposed for the Multi-carrier system. Both methods are particularly suited for small users.     

下一代分布式HLR演进用户数据管理解决方案

介绍了HLR方案对移动网络应用完善与深化的意义和其对整合移动网络带来的变化,从网元层和数据层两个方面分析用户数据给运营商带来的新挑战,重点阐述了用户数据管理(SDM)方案的主要功能和应用.     

3D-MIMO codebook aided multiple user pairing scheme in LTE-Advanced systems简

Two-dimensional（2D） multiple-input multiple-output（MIMO） is currently concentrated on propagation in horizontal plane, but the impact of elevation angle is not considered. However, due to the three-dimensional（3D） character of the real MIMO channel, 2D MIMO cannot achieve the optimal system throughput. A multiple-user MIMO（MU-MIMO） user pairing scheme was proposed, in which the vertical dimension was taken into consideration. In the proposed scheme, a 3D codebook based on full dimension MIMO channel was designed; then two 3D MU-MIMO user＇s pairing schemes are proposed combining the proposed joint and separate 3D codebook. Simulation evaluates the proposed 3D codebook aided user pairing scheme and compares with the previous 2D MU-MIMO user pairing technology. Owing to the additional spatial degree of freedom in vertical dimension, the proposed 3D MU-MIMO user pairing schemes can effectively improve the overall system performance.     

A profile-based strategy for managing user mobility in third-generation mobile systems

Several strategies have been proposed recently to improve the performance of the location management scheme in mobile systems, the influence of mobility on network performance must be reduced, mainly due to the huge number of mobile hosts in conjunction with the small cell size. In this article we present a profile-based strategy (PBS) to reduce location update signaling cost by increasing the intelligence of the location procedure. This strategy associates with each user a list of cells where she is likely to be at a given probability in each time interval. The implementation of this strategy has been subject to extensive evaluation. The results obtained confirm the effectiveness of PBS in significantly reducing the costs of both location updates and call delivery procedures when compared to IS-41 and other well-known strategies in the literature.     

Spatial compatible user grouping algorithm for multiuser MIMO systems

A spatial compatible user grouping algorithm is proposed to reduce CoChannel Interference （CCI） in Space Division Multiple Access （SDMA） multiuser Multiple Input Multiple Output （MIMO） systems. We evaluate the interferences among Users by use of distances between row spaces spanned by users＇ channel matrixes, then control frequency sharing according to the compatible user grouping algorithm. Results show that the row space distance algorithm outperforms others because it can fully utilize the information from users＇ channel matrixes, especially the matrix structure information. The results also prove that the algorithm based on channel matrix structure analysis is a better candidate for spatial compatibility approximation.