E-Band微波在TD-LTE业务回传等传输接入层场景下应用分析

E-Band微波能够提供超大带宽,可用总频宽高达10 GHz,具有比常规微波频段更宽的可调制波道间隔,既是目前民用微波通信领域发布的最高传送频段,也是迄今为止ITU-R一次性发放的频谱资源中波道间隔最大的一次,E-Band微波通信系统能够传输吉比特以上容量的业务.本文重点对E-Band微波在TD-LTE基站回传,大客户集团专线接入及PTN接入层补环建设等各场景下应用可行性进行分析,并对E-Band微波商业化程度进行阐述.     

5G微波性能估算及应用研究

微波是常见的无线传输技术,以其部署快捷、经济有效以及便捷灵活等特点被广泛应用于各类通信系统的中继和回传场景.为满足当前5G网络基站回传带宽需求,基于E-Band 5G微波应运而生,其能够在高频段提供更高的带宽.通过介绍E-Band微波特性,给出E-Band链路预算及容量估算方法,结合实际场景提出部署方案,推动5G网络建...     

微波通信中需要澄清的几个概念

微波通信中需要澄清的几个概念陈堂波道、射频波道、高频波道、相邻波道间隔、交叉极化波道间隔、相邻交叉极化波道间隔，这几个概念是微波通信技术和微波无线电频率管理中常碰到的基本概念。有必要准确分析其内涵和使用范围。下面就来分析和讨论一下这个问题，供大家参考...     

微波电路间干扰估算和协调实例

微波电路间干扰估算和协调实例史为元随着我国通信建设的发展，微波通信的应用越来越广泛，微波频段日趋拥挤。为合理有效地利用微波频率资源，防止微波通信线路之间的相互干扰，新建微波电路的用户向无委提出建站时，无委应对已建同频段的微波电路进行干扰计算，需计算干...     

国际电子龙讯

深圳桑达制成高频轻型数字微波设备深圳市桑达通信联合有限公司设计研制成“高频段轻型数字微波通信设备”。数字微波通信,是利用微波进行数字信号的传输,是近年来在通     

功不可没的微波通信

从广义上讲，LMDS(本地微波分配系统)、MMDS(多通道微波分配系统)、移动通信、集群通信和卫星通信等多种无线通信疗式皆属于微波通信范畴。这是因为微波频段为300MHz至300GHz，而上述几种无线通信方式的工作频率均在此频段。而狭义地说，微波通信另有所指，指的是一种特定的地面通信方式。     

K频段FH-TDD微波设备关键技术分析

为了满足我国紧跟国外微波通信发展的要求,采用时分双工工作方式、跳频抗干扰体制的微波通信机的研制非常必要。K频段FH-TDD微波机是典型的微波视距通信系统,主要用于中/短距离的"点对点"无线链接。能满足在野战环境下对中小容量微波系统的需求。采用时分双工工作方式,简化设备方案及成本,提高频谱资源利用率;采用高频段、高速率跳频(高跳速,高增益)技术,系统具有很高的抗干扰,抗截获能力。本文通过K频段微波设备的总体设计,着重论述K频段FH-TDD微波通信的时分双工控制、跳频控制和跳频同步等关键技术。     

我国1～10Ghz微波接力通信频谱的有效利用

微波接力通信是指利用微波频段的无线电渡传播进行接力通信的方式,微波频段通常是指300MHz一300GHz的频率范围,但并不是全部频段都用于通信业务,而是按照无线电频率划分规定仅将其中一些频段作为微波通信使用频段。其中1—10GHz的微渡由于传播性能稳定,最宜用于无线信道传输,因此很多微波干线都使用它。从而造成这一波段的频率的紧张。国际权威机构认为,频谱的有效利用是国家通信基础结构的一个基本要素,对它的探人研究和严格管理将不断促进国家的经济和社会的发展。无线电频     

探析数字微波通信及其优于光纤的特点和发展对策

随着科学技术的不断发展与进步,为我国通信技术提供了良好的发展空间,而数字微波作为无线通信方式,主要是在微波频段中利用地表视距来交换数字信息,以达到通信的目的,其中包括点对点的数字微波通信和点对面的数字微波通信。文章通过研究数字微波通信及其优于光纤的特点和发展对策,以期提高数字微波通信的利用率,推动通信技术的发展。     

几种国外微波中继通信设备简介

无线电微波通信,是现代化的新型通信方式之一,它采用分米波和厘米波波段(常用的足5-20公厘波段,也就是占500-6000兆赫频段),容量很大,在一个波道内可以同时传送几十路或几百路电话并传送电视节目。在一公共天线上,加装波道分隔滤波器,可以同时发送或接收几个波道。远距离微波通信是靠增设中继站来实现的,中继站问的距离一般是50-60公里,微波发射机的功率一般只有0.5-5瓦。目前微波通信有按频率和按时间划分电话电路两种制式,频率划分制都是采用调频,目前已经用的有24、60、240、600和1860路;     

OFDMA系统中基于伪贝叶斯算法的动态分配随机接入信道策略

Random Access Channel (RACH) is an uplink contention-based transport channel usually used for initial channel access, bandwidth request, etc. How to use RACH resources effectively is very important in wireless communication system. In this paper, a dynamical RACH allocation scheme is proposed for Orthogonal Frequency-Division Multiple Access (OFDMA) systems. Based on the Pseudo-Bayesian algorithm, this mechanism predicts the number of RACHs for the next frame according to the current load. A new dynamic RACH assignment algorithm and an adaptive access probability method are adopted by the proposed scheme to improve the utilization ratio of RACH resources and increase the successful access rate. Numerical simulation shows that the proposed strategy achieves both improvement in the utilization ratio of RACHs and reduction in the access delay compared with other RACH allocation schemes.     

An Adaptive Generalized Transmission Protocol for Ad Hoc Networks

Wireless networking and group communication in combination allows groups of dispersed mobile users to collaborate. This paper presents AGENT, a medium access control (MAC) protocol that unifies point-to-point and multi-point transmission services to facilitate group communication in ad hoc networks. Analysis and experiments performed in a simulated ad hoc network demonstrate that AGENT exhibits reliable and stable performance with high spatial bandwidth reuse. Moreover, variation in the proportion of point-to-point and multi-point traffic is shown to have little impact on the overall performance of AGENT. Comparison with the other tested MAC protocols reveals that the performance of AGENT is superior, achieving higher channel utilization and lower access delay.     

Investigations on heuristic bandwidth request mechanism with signaling analysis for BWA networks

Best effort services in next generation broadband wireless access (BWA) networks would be more interactive and bandwidth demanding. This attracted a substantial amount of researches to focus on contention bandwidth request mechanisms for best effort services. The contention resolution with code division multiple access (CDMA) based mobile assisted truncated binary exponential backoff (C-MAB) suffers low contention efficiency and high access delay due to the nature of accessing mechanism in worldwide interoperability for microwave access (WiMAX) network that confines the mobile station in estimating the optimum contention window. Further, these performances decrease when transmission failure is modeled with unavailability of bandwidth, collision due to contention, transmission code failure, and channel error. To improve the performances, in this paper, we suggest a contention resolution with CDMA based base station assisted backoff (C-BAB) for orthogonal frequency division multiple access (OFDMA) based WiMAX networks. With C-BAB, the base station computes an optimum contention window by accounting average contention window and probability of failure. With a 2.69% additional overhead at the BS, the proposed C-BAB shows a 32.82% increase in contention efficiency and 24.21% decrease in access delay (25% error rate, q = 0.60 and ranging slot = 64) compared to C-MAB.     

Expressnet: A High-Performance Integrated-Services Local Area Network

Expressnet is a local area communication network comprising an inbound channel and an outbound channel to which the stations are connected. Stations transmit on the outbound channel and receive on the inbound channel. The inbound channel is connected to the outbound channel so that all signals transmitted on the outbound channel are duplicated on the inbound channel, thus achieving broadcast communication among the stations. In order to transmit on the bus, the stations utilize a distributed access protocol which achieves a conflict-free round-robin scheduling. This protocol is more efficient than existing round-robin Schemes as the time required to switch control from one active user to the next in a round is minimized (on the order of a carrier detection time), and is independent of the end-to-end network propagation delay. This improvement is particularly significant when the channel data rate is so high, or the end-to-end propagation delay is so large, Or the packet size is so small as to render the end-to-end propagation delay a significant fraction of, or larger than, the transmission time of a packet. Moreover, some features of Expressnet make it particularly suitable for voice applications. In view of integrating voice and data, a simple access protocol is described which meets the bandwidth requirement and maximum packet delay constraint for voice communication at all times, while guaranteeing a minimum bandwidth requirement for data traffic. Finally, it is noted that the voice/data access protocol constitutes a highly adaptive allocation scheme of channel bandwidth, which allows data users to recover the bandwidth unused by the voice application. It can be easily extended to accommodate any number of applications, each with its specific requirements.     

卫星通信系统两步随机接入技术研究

为了实现卫星通信系统低延迟高可靠接入,研究了两步随机接入技术中的信道设计及接收端检测算法.针对卫星场景提出了一种两步随机接入信道设计方案,对两步随机接入信道中数据部分的信道结构以及前导和数据之间的映射方式进行了设计.针对传统最小均方串行干扰消除(Minimum Mean Squared Error-Successive Interference Cancellation,MMSE-SIC)算法中存在误差传播问题导致解码性能降低的问题,提出了一种多判决排序串行干扰消除(Multi-decision Ordered Successive Interference Cancellation,MD-OSIC)算法,以提升多用户发起接入时数据部分检测的可靠性.仿真结果验证了所设计信道及检测算法在典型卫星通信场景下应用的可行性.     

多信道车载网中基于时分多址的MAC改进算法

车载网(VANETs)需提供时延敏感的安全应用和非安全应用的通信服务.这就使得媒体接入控制(MAC)协议既要满足安全消息的时延和可靠率,又要保证非安全消息的服务信道利用率,给MAC的设计提出了挑战.为此,提出基于时分多址的MAC改进算法(I-TDMA-MAC).I-TDMA-MAC算法在每个同步帧内给每辆车分配两个子时隙,旨在提高无碰撞信道接入率和安全消息的传递率.同时,对空闲时隙采取重分配策略,并基于最短作业优先准则(SJF)给空闲时隙设置优先级,旨在提高服务信道利用率.仿真结果表明,提出的I-TDMA-MAC算法的安全消息传递率高达99%,当车流密度到达100 vehicle/km时,服务信道利用率接近于90%.     

一种多接口接入系统的网管功能的设计与实现

本多接口接入系统基于光纤环路传输设备，采用同步复接技术，提供多种64Kb／s速率的终端接口。提出了该接入系统网管功能的一种实现方案，利用了现有系统提供的串行通道和E1链路同步时隙提供的20Kb／s通道，设计了多套接入系统与网管PC间的多机通信方式、通信协议、以及接入系统中的控制软件和网管PC中的管理软件，实现了一套灵活有效的网管系统，提高了接入系统的可监管性和易用性。     

一种数字式微波延迟线设计

通过混频将微波信号下变频到中频,在中频进行数字化,并采用循环存取法完成数字信号延迟处理,最后再将数字信号还原成模拟信号并上变频回与输入信号频率相同的微波频段,最终设计出频率4 300MHz、带宽70MHz、最大延迟时间50μs、延迟步进5ns的微波频段延迟线,该产品有很好的直通及三次信号抑制性能。     

宽带综合业务接入网——数字化生活的基石

文章从通信网络的发展趋势出发,阐明了宽带接入网的发展方向和接入网目前常用的接入技术,论述了国内通信网尤其是接入网的宽带化和IP化的必然趋势及解决方案。     

面向应用的短距离无线通信系统信道接入机制

自组方式短距离无线通信具有设备简单、使用方便及成本低等特点,因此成为研究和应用的热点,其信道接入是关键技术之一。针对短距离无线通信系统在现实应用中的信道接入问题,论述了两种信道接入机制———轮询方式和竞争方式。从工作原理、性能、优缺点等方面对这两种机制进行了比较,以系统成本、复杂度、性能指标等为参数分析了各自的应用。分析表明,两种信道接入机制各有特点,适合不同的条件,是实用的自组方式的无线接入方式。