基于MSC Pool技术的多池组网规划优化分析

本文针对MSC Pool技术在移动通信网络质量提升方面的应用效果进行实施前后以及应用后不同本地网间的横向、纵向比对分析,针对中,大型本地网内多池区组网规划方案进行了深入的研究和优化,梳理出MSCPool组池规划的关键点以及实施原则,为今年在全网大规模部署的MSC Pool组池规划优化以及如何最大化发挥MSC Pool技术在网络质量提升方面的优势提供相应的参考意义.     

基于LTE的话音回落技术应用

本文基于CS Fallback技术的移动性管理流程和话音呼叫流程,分析了在一般场景下及MSC Pool场景下,CSFallback应用所面临的问题以及可能的解决方案.最后给出了在LTE网络部署CS Fallback的建议.     

MSC Pool组网与传统组网的位置更新比较

简要介绍了传统组网和MSC Pool的技术原理及组网方式;对比分析了这2种组网方式下的3种位置更新,即移动台的位置更新、用户跨MSC Pool的位置更新及周期性位置更新;说明了MSC Pool组网方式较传统组网方式因消除了池内跨局位置更新,从而更好地释放了HLR和MSC的处理能力,提高了通信网络的可靠性和可用性。     

基于Iu_flex的MSC Pool技术分析

MSC池(MSC in Pool)是由3GPP规范定义的,能优化整个移动网络的组网.本文简要介绍了MSC Pool技术的基本原理及其组网特点,分析了MSC Pool所用到的关键技术(NRI路由机制和负荷分担),重点讨论了核心网D接口信令的流量,根据MSC Pool的技术特点,提出了组网规划的前提条件和规划时需要注意的问题,最后总结了MSC Pool技术的特点,在结论部分给出了MSC Pool可能存在的安全隐患.     

2G/3G共核心网的MSC Pool组网策略

MSC Pool技术在网络容灾和合理分配网络资源方面有其明显的优势.在2G/3G网络并存并逐步融合的网络发展大趋势下,如何在网络中合理运用这种技术是一个有研究价值的课题.本文从MSC Pool的基本组网方式出发,结合网络发展的趋势,讨论了在2G/3G共核心网的情况下CS域中MSC Pool组网的策略.     

基于lu_flex的MSC Pool技术分析

MSC池（MSCin Pool）是由3GPP规范定义的,能优化整个移动网络的组网。本文简要介绍了MSC Pool技术的基本原理及其组网特点,分析了MSC Pool所用到的关键技术（NRI路由机制和负荷分担）,重点讨论了核心网D接口信令的流量,根据MSC Pool的技术特点,提出了组网规划的前提条件和规划时需要注意的问题,最后总结了MSC Pool技术的特点,在结论部分给出了MSC Pool可能存在的安全隐患。     

基于Iu_flex的MSC Pool技术分析

MSC池（MSCin Pool）是由3GPP规范定义的,能优化整个移动网络的组网。本文简要介绍了MSC Pool技术的基本原理及其组网特点,分析了MSC Pool所用到的关键技术（NRI路由机制和负荷分担）,重点讨论了核心网D接口信令的流量,根据MSC Pool的技术特点,提出了组网规划的前提条件和规划时需要注意的问题,最后总结了MSC Pool技术的特点,在结论部分给出了MSC Pool可能存在的安全隐患。     

基于MSC Pool集中备份方案N+1方式的研究

本文对浙江移动网络中的MSC Pool的被叫恢复方案进行了探索、测试、研究.从网络结构、维护便利性、以及投资经济性、网络安全性各个角度出发,对MSC Pool的备份方案进行了探究、优化和创新,实现现网中集中备份设备进行N+1方式的独特应用.     

MSC Pool组网相关问题分析

引入MSC Pool技术的一大优势是使网络能够依据MSC的处理能力按比例分配话务,实现话务在MSC pool内所有MSC中的合理分配,并能把某个区域突发的高峰话务分配给多个MSC分担处理,避免对整个网络造成冲击。对单个MSC来说没有负荷高峰,充分利用MSC Pool内交换设备的已有网络资源,降低单个MSC拥塞的风险,提高网络利用率。     

引入MSC Pool技术后网络管理面临的问题分析及解决方案

本文介绍了MSC Pool的引入背景和技术特点,对MSC Pool引入后带来的网络管理方式变化进行了分析,并针对MSC Pool不同于现有网络管理方式的特点提出了解决方案。     

Pros and cons of fine granular scalability-based MPEG-2 compressed-domain processing

The pros and cons of FGS-based MPEG-2 video transcoding are examined. An existing solution for elastic storage of media (Barrau, 2002) is reviewed. Its shortfalls in terms of picture drift are identified and addressed by means of proposing a modified transcoding architecture, which is then compared to SNR-based MPEG-2 multilayer transcoding. It is shown that the FGS-based MPEG-2 video transcoder has the advantage of simplified transcoding and decoding architectures. However, the SNR-based MPEG-2 transcoder is shown to produce higher quality reconstructed images with superior rate-distortion performance.     

一种基于DSP的H.264到H.263实时转码器

设计了一种基于DSP的H.264到H.263实时转码器,充分利用视频编解码过程的冗余信息,对传统结构的转码器进行改进,降低了转码运算复杂度.结合TMS320DM642的特点在DSP平台上完成了这两种转码器的优化实现.最终实验数据表明,传统结构转码器优化后转码速度能达到20f/s(帧/秒),而所设计的转码器则能实现CIF格式25f/s从H.264到H.263的实时转码,并且没有显著的视频质量损失.     

Advances in network-supported media delivery in next-generation mobile systems

This article presents new concepts for network-supported media delivery in mobile networks. Automatic composition and merging of networks are central parts of these concepts. Media delivery is no longer an end-to-end service that only uses the network as an IP transport. Instead, these concepts create a service-aware network and provide customized delivery support through per-service overlay networks. They also integrate specialized processing nodes as part of the delivery topology, which include transcoders but also more complex processors, such as localized program insertions or personalized spam control. This article describes the underlying concepts and how these new network capabilities for media delivery services are requested, invoked, and managed.     

Fast computation of MC-DCT for video transcoding

A fast method to reduce the computational complexity of a frequency domain transcoder for bit-rate reduction of compressed video bit streams is proposed. The proposed method reduces the computational complexity of a pixel domain transcoder by 81.25% while the introduced distortion in the transcoded pictures is 0.2 dB     

Error-resilient transcoding for video over wireless channels

We describe a method to maintain quality for video transported over wireless channels. The method is built on three fundamental blocks. First, we use a transcoder that injects spatial and temporal resilience into an encoded bitstream. The amount of resilience is tailored to the content of the video and the prevailing error conditions, as characterized by bit error rate. Second, we derive analytical models that characterize how corruption propagates in a video that is compressed using motion-compensated encoding and subjected to bit errors. Third, we use rate distortion theory to compute the optimal allocation of bit rate among spatial resilience, temporal resilience, and source rate. Furthermore, we use the analytical models to generate the resilience rate distortion functions that are used to compute the optimal resilience. The transcoder then injects this optimal resilience into the bitstream. Simulation results show that using a transcoder to optimally adjust the resilience improves video quality in the presence of errors while maintaining the same input bit rate     

Video Transcoding with H.263 Bit-Streams

Video transcoding is one of the key technologies in implementing dynamic adaptation of the bit-rate of a coded video bit-stream to the available bandwidth over various networks. Many fast transcoder architectures have been proposed to achieve fast processing. However, they suffer from quality degradation caused by the drift error. In this paper, we investigate the drift caused by the fast transcoder architectures for transcoding H.263 bit-streams. We discuss the limitations of the fast transcoder architectures and the flexibility that can be offered by a cascaded pixel-domain transcoder. Since the cascaded pixel-domain transcoder can achieve drift-free performance, we also propose methods to reduce the computational complexity of the drift-free cascaded pixel-domain transcoder.     

Compressed-Domain Techniques for Error-Resilient Video Transcoding Using RPS

In video applications where video sequences are compressed and stored in a storage device for future delivery, the encoding process is typically carried out without enough prior knowledge about the channel characteristics of a network. Error-resilient transcoding plays an important role to provide an addition of resilience to the video data, where or whenever it is needed. Recently, a reference picture selection (RPS) scheme has been adopted in an error-resilient transcoder in order to reduce error effects for the already encoded video bitstream. In this approach, the transcoder learns through a feedback channel about the damaged parts of a previously coded frame and then decides to code the next P-frame not relative to the most recent, but to an older, reference picture, which is known to be error-free in the decoder. One straightforward approach of adopting RPS in error-resilient transcoding is to decode all the P-frames from the previously nearest I-frame to the current transmitted frame which is then re-encoded with a new reference frame; this can create undesirable complexity in the transcoder as well as introduce re-encoding errors. In this paper, some novel techniques are suggested for an effective implementation of RPS in the error-resilient transcoder with the minimum requirement on its complexity. All the proposed techniques will manipulate video data in the compressed domain such that the computational loading of the transcoder is greatly reduced. By utilizing these new compressed-domain techniques, we develop a new structure to handle various types of macroblocks in the transcoder which re-uses motion vectors and prediction errors from the encoded bitstream. Experimental results demonstrate that significant improvements in terms of transcoder complexity and quality of reconstructed video can be achieved by employing our compressed-domain techniques.     

基于模式对应与机器学习的HEVC降分辨率转码算法

HEVC是ITU-T VCEG 继H.264之后所制定的新的视频编码标准,它提高了视频的编码效率,在相同视频质量的前提下,压缩比与H.264相比提高了一倍。另外,随着4G网络的兴起和智能手机的普及,移动终端成为人们观看网上视频的一大主流平台。但是,网络中存储的视频分辨率普遍要大于移动终端屏幕分辨率,为解决这个问题,本文开展了针对HEVC的降分辨率转码研究工作,利用高分辨率视频的编码信息,通过模式对应来简化低分辨率视频的编码模式的计算过程,并采用机器学习的方法来确定降分辨率时的组块阈值,以提高模式对应的准确性。实验结果表明,提出的算法与Trivial transcoder相比,在保持PSNR和比特率几乎不变的同时,编码时间平均节省了60%左右。     

从AVS到MPEG-2的转码算法研究

介绍了视频转码的几种基本技术，分析了MPEG-2与AVS的不同，提出了一种从AVS到MPEG-2的转码系统．针对关键的转码算法设计了一种综合优化方案，实验显示图像质量和压缩率都有明显提高。     

On re-composition of motion compensated macroblocks for DCT-based video transcoding

To achieve portability between different kinds of encoding formats and network environments, heterogeneous video transcoding becomes a key technique for reducing the bitrate of a previously compressed video signal. A frame-skipping transcoder is often used to avoid an unacceptable picture quality when high transcoding ratio is required. Due to high computational complexity and quality degradation introduced by conventional frame-skipping transcoders, a DCT-based video frame-skipping transcoder has been proposed recently. However, the transcoding process of the motion compensated macroblocks in the DCT domain becomes the bottleneck since IDCT and DCT processes are required. In this paper, we propose a new architecture of the frame-skipping transcoder to reduce the computational complexity of motion compensated macroblocks in the frame-skipping process. The new architecture transcodes the dominant region of a motion compensated macroblock in the DCT domain by making use of the DCT coefficients of the incoming bistream and some pre-computed shift operators. By using a shifted version of the dominant vector, the re-encoding error introduced in the dominant region can be avoided. On the other hand, an adaptive transcoding architecture to transcode the boundary regions of MC marcoblocks and a way to perform error compensation are proposed. This architecture can further speed up the transcoding process of the motion compensated macroblocks. Half pixel accuracy related to our proposed frame skipping transcoder is also addressed. Experimental results show that, as compared to the conventional or DCT-based transocders, the new architecture is more robust to noise, gives rise to fewer requantization errors, and requires simple computational complexity.