多速率自适应技术在Ir协议中的应用

以TI公司的TLK10002为例,研究了多速率环境下的PRU设备自适应接入问题,给出了RRU设备速率自适应的流程图和方法。采用本方案的RRU设备,能够自动进行通信速率调整,极大地降低了网络建设难度和工作量,具有广阔应用前景。     

无线Ad hoc网络速率自适应MAC协议研究

无线Ad hoc网络多采用IEEE802.11系列标准,在物理层为数据传输提供了多速率能力。为了充分利用多速率能力提高系统的吞吐量,速率自适应MAC协议根据对当前信道质量的估计,选择最佳的数据传输速率。在分析了速率自适应MAC协议的基本工作过程之后,重点综述了目前存在的速率自适应MAC协议,并讨论了进一步研究的方向。     

软计算方法在自适应多速率话音激活检测中的应用研究

本文提出一种新的话音激活检测方法，该方法基于软计算理论，应用于3GPP标准化的自适应多速率语音编码算法，从剪音和噪声误判为语音概率两个方面分析其在不同背景噪声环境中的性能，仿真表明：基于客观评价方法，这种新的话音激活检测算法比ITU G．729B建议算法性能更好．     

一种基于IEEE 802.11的多速率自适应MAC协议

提出了一种新颖的基于连续ACK帧统计信息的IEEE 802.11多速率自适应MAC协议EARF(EnhancedARF),其主要思想是:每一个速率有各自的成功阈值——速率升高的门限值,并且该值根据信道状况(用延时因子量化)动态地变化。协议不需对现有的IEEE 802.11标准做任何修改,因此易于通过编写驱动程序实现。仿真表明在大多数信道条件下,该协议性能较现有的基于ACK帧统计的速率自适应协议如ARF,ARF3-10都有较大的提高。     

自适应多速率技术在GSM中的应用

文章介绍了AMR的原理,阐述了AMR对GSM网络的影响,并针对话务分布和AMR的特点引入了AMR的应用方案。指明了AMR技术的适用场景、应用原则与步骤,以及全速率与半速率的切换原则,为AMR部署提供了参考。     

自适应多速率编码简介

随着手机用户的不断增加，移动网络进行了多次的扩容，扩容方式一般通过增加基站和增加载频来实现。由于同一地区的基站增多．基站的站间距就必然变小；同时由于可用的频率资源有限．导致平均十扰上升、载干比(C／I)下降。明显的后果就是手机通话时声音听不清楚，或者有各种各样的噪声。一般来说，提高通     

宽带自适应多速率声码器

介绍了3GPP组织最新推出的宽带自适应多速率声码器AMR－WB，编解码原理以及速率控制机制等。较窄带语音编解码器，在语音的自然度效果及抗噪声能力等方面有较大改善。     

无线Ad Hoc网络MAC层速率自适应技术研究

目前的IEEE802.11标准虽然在物理层提供了对多速率的支持,但是在MAC（媒体接入控制,Media Access Control）层却没有规定速率自适应的方法。研究了无线Ad Hoc网络（自组织网）中的速率自适应技术,针对RBAR协议存在的不足提出了一种改进的MAC层速率自适应协议,该协议实现简单,与标准的兼容性好,对信道的变化适应能力更强。仿真结果表明,该协议比RBAR协议具有更好的性能。     

多速率CDMA系统自适应接收机

随着移动通信的发展，多速率数据通信业务越来越多。第三代移动通信系统能够支持可变服务质量的不同数据速率业务。因此，多速率接收机的研究也越来越引起重视。多速率系统中，当干扰信号具有不同速率参数时，不同用户的周期平稳性不同，单速率自适应FIR接收机的性能会严重下降。提出了一种适合于多速率多址干扰下的自适应滤波器组接收机，仿真结果表明，自适应滤波器组接收机能够更有效地消除多种模式的多址干扰，比单速率接收机具有更好的性能。     

一种新的多用户多速率自适应MC-DS-CDMA传输方案

从有效利用网络资源的角度出发,结合OFDMA的动态资源分配策略,提出了一种灵活支持多用户多速率业务的改进MC-DS-CDMA传输方案--自适应MC-DS-CDMA系统。仿真结果表明,自适应MC-DS-CDMA系统由于采用了多用户自适应的子载波分配策略,不仅可灵活支持多速率业务,而且能降低系统的发射总功率,进一步改善了系统性能。     

Efficient cross-layer protocol for bandwidth-satisfied multicast in multi-rate MANETs

Since the multi-rate enhancements have been implemented in 802.11 wireless networks, QoS-constrained multicast protocols for multimedia communication should be adapted to exploit them fully. This work proposes a multicast protocol for data rate selection and bandwidth-satisfied multicast tree determination with an efficient cross-layer design based on the integration of PHY and MAC layers into the network layer. To use bandwidth efficiently and increase network capacity (which is the number of multicast flows supported by the network), we aim to select the combination of data rates and a multicast tree whose total amount of bandwidth consumption to the network is minimal in order to maximize the network capacity. The performance of the proposed protocol is compared with two existing protocols. Simulation results indicate that the proposed protocol has the ability to admit more multicast flows.     

Relay-volunteered multi-rate cooperative MAC protocol for IEEE 802.11 WLANs

In IEEE 802.11, the rate of a station (STA) is dynamically determined by link adaptation. Low-rate STAs tend to hog more channel time than high-rate STAs due to fair characteristics of carrier sense multiple access/collision avoidance, leading to overall throughput degradation. It can be improved by limiting the transmission opportunities of low-rate STAs by backoff parameters. This, however, may cause unfair transmission opportunities to low-rate STAs. In an attempt to increase overall throughput by volunteer high-rate relay STAs while maintaining fairness, we propose a new cooperative medium access control (MAC) protocol, relay-volunteered multi-rate cooperative MAC (RM-CMAC) based on ready to send/clear to send in multi-rate IEEE 802.11. In the RM-CMAC protocol, we show that the effect of hogging channel time by low-rate STAs can be remedied by controlling the initial backoff window size of low-rate STAs and the reduced transmission opportunity of low-rate STAs can be compensated by the help of volunteer high-rate relay STAs. We analyze the performance of RM-CMAC, i.e., throughput and MAC delay, by a multi-rate embedded Markov chain model. We demonstrate that our analysis is accurate and the RM-CMAC protocol enhances the network throughput and MAC delay while maintaining the fairness of low-rate STAs.     

自适应混合光交换的研究

针对已有混合光交换的不足之处,提出了自适应混合光交换.这种光交换方式能根据网络业务的状态,自适应调整光交换方式,从而提高了链路利用率,降低了网络丢包率.同时讨论了自适应混合光交换的边缘节点、核心节点的结构及其各部分功能.     

居民区TD-SCDMA无线网络覆盖策略研究

本文主要研究居民区TD-SCDMA覆盖策略,首先通过对6种居民区覆盖策略进行理论分析和对比,找到一种适合大型居民区的TD-SCDMA覆盖策略--BBU和RRU组成的室外分布式基站覆盖策略,然后通过仿真和实际测试,分析各种网络性能指标,对该种覆盖策略进行验证,并得出相应结果.     

A Cooperative Channel Assignment protocol for multi-channel multi-rate wireless mesh networks

Wireless mesh networks (WMNs) are considered as one of the outstanding technologies that provide cost-effective broadband Internet accesses to users. The off-the-shelf IEEE 802.11 PHY and MAC specifications support both multi-channel and multi-rate capabilities. However, designing an efficient channel assignment protocol that exploits both available channels and data rates is a critical issue to overcome the network performance degradation. In multi-rate wireless networks, high-rate links may severely suffer from throughput degradation due to the presence of low-rate links. This problem is often referred to as performance anomaly. In this paper, we design a Cooperative Channel Assignment (CoCA) protocol to consider the performance anomaly problem in multi-channel multi-rate WMNs. Based on the proposed family architecture, CoCA exploits the Estimated Delivery Time (EDT) metric and an efficient balancing algorithm. Using the EDT metric, CoCA performs channel assignments to form Multi-channel Multi-hop Paths (MMPs) so that CoCA separates high-rate links from low-rate links over different channels and increases the channel diversity. In addition, CoCA considers the performance anomaly problem and throughput fairness during channel assignments by utilizing the balancing algorithm. We evaluated the performance of CoCA through extensive simulations and found that CoCA outperforms existing well-known channel assignment protocols for WMNs.     

RRU基本原理及应用分析

文章首先介绍了RRU的组成及其基本工作原理,分析了采用数字光纤传输技术和数字中频技术的优缺点,结合工程实际测量结果对宏蜂窝与RRU在覆盖范围,性能等方面进行了分析比较.得出RRU在3G网络的建设中具有广阔的市场应用前景.     

TD-SCDMA分布系统"RRU+干线放大器"创新应用及测试

本文提出并从技术上论证了TD-SCDMA室内覆盖工程中分布系统"RRU 干线放大器"的创新使用方式,为TD-SCDMA室内覆盖工程提供了一种新的覆盖方式,主要适用于两类场景,可提高工程的可实施性,降低物业协调的难度,提高室内覆盖点的通信服务质量.     

GSM“载频池”技术应用分析

本文首先介绍了GSM“载频池”的概念和引入背景;随后对其具体实现方式及应用场景进行了深入分析,并与传统建网方式进行了对比;最后对“载频池”技术进行了总结,并给出了该技术的定位和应用建议。     

利用RRU实现动力环境监控的研究与实现

为解决原有室外电源柜监控方式投资大、效果差、不稳定等问题,通过深入研究华为、中兴、动力源和珠江等室外电源柜监控特性,提出了利用RRU干接点实现对室外电源柜交流停电、门禁和欠压等主要数据的采集的解决方案,并对利用RRU干接点实现对室外电源柜动力环境监控的思路、方案优势等方面进行了分析。