移动通信基站动环监控IP组网方案

随着网络技术的不断普及,IP技术的不断成熟,现在正普遍采用的移动通信基站动力监控抽时隙方式已不能适应对基站动环监控系统的稳定性要求,本文通过对基站动力环境监控系统结构和传输网络的特点进行研究分析,提出了基站动力环境监控系统传输的改进方案,从根本上提高基站动环监控系统的稳定性及监控系统应用功能的拓展性.     

基于DSP的DMR终端时隙同步设计与实现

时隙同步是TDMA无线集群通信系统能够正常工作的至关重要的一个环节。关于时隙同步的研究大部分集中在同步位置搜索算法上,却鲜有如何在具体平台上系统实现的介绍。根据DMR协议独特的彼此正交或负相关同步序列,通过搜索这些位于突发中间的同步序列可以计算出当前解调数据中同步序列所处的位置,然后再产生DMA中断及定时器中断时,计算出定时器所需定时的长度,重新设置定时器寄存器值,调整定时器定时长度使得定时器中断与时隙边沿同步。实际测试证明该方法的同步误差在10μs以内,满足DMR协议系统要求。     

无线传感器网络中一种动态节能的MAC协议

媒体访问控制(MAC)协议是无线传感器网络的关键协议之一,它对无线传感网络的运行和性能具有重要的影响.针对基于簇的TDMA机制存在问题,文中提出了一个动态节能的DE-MAC协议,该协议能够根据簇成员节点数目和通信负载动态地分配成员节点的时隙,减少节点的空闲侦听时间.仿真结果表明,DE-MAC协议能够有效地提高信道的利用率和网络能量有效性.     

Physical Frame Time-Slot Technique Switching- A New Switching over DWDM

A novel technique called physical frame time-slot switching （PFTS） is discussed and its technical and application aspects are analyzed. The format of the ethernet media access control （MAC） frame is borrowed in defining the physical frame for PFTS and the transmission time for the maximum size of the MAC frame is defined as a physical frame time-slot （PFT）. Consequently, user data can be fed into PFTS and switched in a single layer sub-network in an asynchronous mode.     

基于簇的无线传感网络流量负载的时隙调度协议*

针对大规模的无线传感器网络MAC协议在能量有效、低延时等方面的不足,提出一种基于簇的自适应时隙调度协议（ATSP）。整个网络由一些较小单位的簇组成,在每个簇内构造一棵数据聚集树,根据数据聚集树对节点每轮需要发送的数据流量进行加权,决定该节点的时隙大小;然后由簇头动态调节簇内节点时隙更新频率和顺序,可以降低时隙划分的能量和时间代价,减少节点的空闲侦听时间,避免串音。仿真表明,该协议有效地提高了网络能量有效性,延长了网络生存周期,降低数据包的延时。     

Performance Models for Multi-rate Circuits in Switched Multi-Channel Optical Networks

We consider optical networks with nodes interconnected by links comprising multiple channels. The blocking performance of such networks depends on the channel-switching capabilities of the nodes. In this paper, we focus on developing analytical models for evaluating the blocking performance in circuit-switched optical networks. Several architectures for channel-switching are presented. Multi-rate circuits may be established if different circuits are allocated different number of channels. Depending on how the network can assign the channels to circuits that request more than one channel, it is classified as a Data Splitting Network (DSN) or a non-DSN. We consider multi-rate circuits which require either a single channel or a given number of channels k (>1). Analytical models for computing blocking probabilities are developed for various channel-switching architectures at the nodes. The validity of the models is shown by comparing the analytical results with simulations. Numerical results in a single-fiber TDM wavelength-routing network suggest that limited channel-switching may be sufficient even for circuits that require more than one channel or slot. A comparison of DSN and non-DSN shows that data splitting can accommodate more multi-slot circuits at the expense of blocking more single-slot circuits.This work was supported in part by NSF Grants ANI-9973098 and ANI-9973111     

BSC光口化传输网络规划与实践

移动BSC业务传输网络接口逐渐由2Mbit/s接口向155Mbit/s光口演化,为了应对这一主流变化,本文结合某移动公司网络现状和业务网电路流量和流向等特点,重点论述了新的网络规划模式和建设方案,并对移动传输网如何有效地进行电路调度、应用,进行了详细分析.     

DMR标准物理层接收算法设计

DMR物理层标准采用的是4FSK调制技术,其具有TDMA双时隙结构、频谱效率高、通信距离远、抗干扰能力强以及语音数据业务功能丰富等特点。DMR标准提高了频谱使用率,扩大了通信容量,提高了沟通效率,节约了使用成本,使用户获得高效的无线通信服务。在此介绍了一种基于差分解调结构的接收算法,该算法易于实现,并且接收灵敏度满足DMR测试指标。     

同步无线Mesh网络带宽申请与分配策略的改进

数据通信具有突发性与带宽计算的不确定性,现有同步无线Mesh网络带宽申请与分配策略未对此问题进行充分考虑,在设计上存在带宽申请速度慢、带宽分配没有最大化、将数据时隙区分了上下行等不足,导致了QoS保障能力低与网络性能的下降。提出了带宽申请与分配策略的改进方案,包括结合各类数据业务类型的带宽申请条件的描述、检查数据发送队列的时间间隔描述、带宽分配最大化的描述、数据时隙不再区分上、下行的描述。理论分析表明,改进后的方案能够提供精确的QoS保障并提高网络性能。     

A distributed media access protocol for packet radio networks and performance analysis. Part 1: Network capacity

A distributed time-slot assignment protocol is developed for a mobile multi-hop broadcast packet radio network, using time division multiple access channel access and virtual circuit switching. The protocol eliminates the single point failure mode of centralized network management and the delays of centralized processing. It is applicable to the user-to-user communications functions of such systems as the U. S. Army's enhanced position location and reporting system (EPLRS). The important functions of the distributed protocol, including time-slot assignment, virtual circuit set-up, and network synthesis, are identified, and implementing algorithms are presented and verified. The performance analysis of the protocol is divided into two parts. In this paper, Part 1 of the performance analysis, the capacity of a network using this protocol is studied and a tool is developed to design the network capacity by trading off among the network area, the transmission range, and the number of packet radio units. Since these results are not in closed form, numerical results provide insight into these parameters. In Part 2 the network set-up time and network data rate are analysed and a hierarchical architecture for the distributed protocol is proposed and analysed.