Network Dimensioning in WDM-Based All-Optical Networks

The problem of network dimensioning, which involves optimal network designs using minimal resources for a given well-predicted traffic between individual nodes but without a pre-determined network topology, is analyzed in details in this paper. Such optimal designs are critical as the network resources are directly related to the cost of implementation. The problem complexity increases as the traffic between every node pair varies in a periodic manner. Furthermore, the presence of wavelength conflicts makes the network-dimensioning problem distinct and more complicated than that for traditional circuit-switching networks. Here, we adopt the approach based on a multi-commodity flow problem. A general cost function covering the resources of all system components is formulated, and two solution approaches are presented; one based on integer programming and one on heuristics.     

Modeling a Mobile Cellular Network Using a Discrete-Event Simulator

In this paper we introduce a discrete-event-based simulation technology suitable to model cellular mobile radio systems with respect to their dynamic behavior. The latter results in the need for simulation tools which support mutable system configurations. The problems encountered when modeling mutable system configurations using conventional discrete-event simulators are discussed. In order to show a possible solution to this problem we introduce configuration events and configuration objects into the theory of discrete-event simulations. We demonstrate how configuration objects can be implemented in a discrete-event simulator using a dynamic map-function, hereby extending a definition of higher order functions. We apply the configuration objects in a Multiple Layer Model for modeling an entire mobile cellular radio network in a discrete-event simulator as an application for the extended theory. In this model we use the configuration objects to change the network's configuration during runtime. We show that this solution—combined with an object-oriented software design and, possibly, a visual programming language—is a powerful tool for the simulation of the dynamic aspects of mobile cellular radio networks. The software technology presented will be applied by the German cellular network operator Mannesmann Mobilfunk to model dynamic features applicable to the radio resource management of mobile radio networks and to access their performance by simulation.     

中继蜂窝网络下行协作网络编码中继方法

In this paper, we first overview some traditional relaying technologies, and then pre-sent a Network Coding-Aware Cooperative Relaying (NC2R) scheme to improve the performance of downlink transmission for relay- aided cellular networks. Moreover, sys-tematic performance analysis and extensive simulations are performed for the proposed NC2R and traditional relaying and non-relaying schemes. The results show that NC2R outperforms conventional relaying and non-relaying schemes in terms of blocking probability and spectral efficiency, especially for cell-edge users. Additionally, the location selections for relays with NC2R are also dis-cussed. These results will provide some insights for incorporating network coding into next-generation broadband cellular relay mo-bile systems.     

LEO-Mesh卫星光网络容量规划

利用低轨卫星网格状结构光网络的空间对称性,推导了网络流量平衡特性,进而以最小丢包率为目标,采用Lagrange乘数法对各端口容量进行优化配置.在由m条轨道、每个轨道n颗卫星构成的Mesh型卫星光网络中,轨道内端口容量与m成反比,与对地接入端口速率比约为n/8;轨道间端口容量与n成反比,与对地接入速率比约为m/8.在初始配置下,丢包率在m=n时取得极小值;经优化配置之后,各端口利用率趋于平均,丢包率较优化前有明显下降,且随着卫星数量增加呈持续下降趋势.     

Software-Defined Cellular Mobile Network Solutions

The emergency relating to software-defined networking(SDN),especially in terms of the prototype associated with OpenFlow,pro-vides new possibilities for innovating on network design.Researchers have started to extend SDN to cellular networks.Such newprogrammable architecture is beneficial to the evolution of mobile networks and allows operators to provide better services.Thetypical cellular network comprises radio access network(RAN)and core network(CN);hence,the technique roadmap diverges intwo ways.In this paper,we investigate SoftRAN,the latest SDN solution for RAN,and SoftCell and MobileFlow,the latest solu-tions for CN.We also define a series of control functions for CROWD.Unlike in the other literature,we emphasize only software-defined cellular network solutions and specifications in order to provide possible research directions.     

蜂窝网络和Ad Hoc网络综述

文章首先分别介绍了无线通信网络中的蜂窝网络及Ad Hoc网络的概念、发展及特点,分析了两者的不同及联系.之后又讨论了这两种网络中的信道分配问题:对于蜂窝网络介绍了基本的信道分配策略;对于Adhoc网络介绍了单频、双频和多频各自的频率分配特点.最后展望无线通信网络的发展方向和未来.     

多跳蜂窝网络中的代理选取问题研究

自组织网和蜂窝网是移动通信系统的重要组成部分,融合两者的多跳蜂窝网络将可能成为未来移动通信系统的重要组成形式之一.文中介绍了多跳蜂窝网络的研究现状,分析了各网络模型的特性,并对现有网络架构进行了类型划分.在此基础上,对多跳蜂窝网络的代理选取问题展开研究,提出了一种代理选取问题的分析模型,并基于该模型的节点通信半径、节点密度和小区半径等参数对代理选取概率的影响进行了仿真分析.     

The Impact of Mobility on Cellular Network Configuration

This paper proposes a model for configuring cellular networks to study the dynamics of mobility between a single cell and its adjacent cells. It differs from most models considered in the literature by explicitly incorporating the dependency between the handoff rate and the system state. Besides, the handoff rate is also a function of cell size and subscriber mobility. Extensive computational experiments were done to study the impact of various input parameters on specific performance measures. Several observations are made regarding the system performance and as to how they are affected by the complex interaction between subscriber mobility, cell size, number of channels and the mean call initiation rate. The results of these experiments show that the proposed model, where handoff rates are state-dependent, captures additional traffic due to mobility when compared to the traditional method of modeling handoffs using information about the average behavior. Finally, the economic impact of mobility on system configuration decisions is analyzed. Though an approximation, the above work provides interesting insights about the impact of mobility in configuring cellular networks.     

无线局域网和蜂窝移动网络融合技术研究

通过3GPP在WLAN和移动网络融合的标准情况介绍,给出了WLAN与3G网络两种融合架构,详细分析了IP地址分配、移动性管理的相关流程。     

二维量子细胞神经网络及其图像处理应用

以量子细胞自动机为神经元,以量子细胞自动机的极化率和量子相位为状态变量,提出了一种二维多层的量子细胞神经网络结构;以量子细胞自动机的极化率为像素值,通过选择不同的模板,使得量子细胞神经网络实现水平线和垂直线检测以及图像去噪等功能,仿真结果显示其在图像处理上的有效性。与传统的CNN相比,量子细胞神经网络易于超大规模实现且具有超低功耗、超高集成度等优点。     

Asymmetric FCA for Downlink and Uplink Transmission in Clustered Multihop Cellular Network

A clustered multihop cellular network (CMCN) with virtual cells has been proposed to achieve the characteristics of macrocell/microcell hierarchically overlaid architecture by applying clustering techniques. As a complement to the traditional cellular networks, CMCN is able to incorporate the flexibility of ad hoc networks by allowing multihop transmission. In this paper, we first propose to use dedicated information ports (DIPs) as clusterheads for CMCN; then we analyze the performance of fixed channel assignment (FCA) for downlink transmission in CMCN. Two multi-dimensional Markov chain models are developed to study the call blocking probability. Due to the nature of multihop transmission in CMCN, channel assignment for uplink and downlink transmission is different and unbalanced. We then propose an asymmetric FCA (AFCA) for uplink and downlink transmission in CMCN. By making use of the proposed AFCA for uplink and downlink transmission, we can reduce the call blocking probability significantly as compared with the FCA for traditional single-hop cellular networks. The salient contribution is that the proposed CMCN with AFCA scheme can increase the spectrum efficiency and the system capacity by introducing the structure of CMCN with DIPs for virtual microcells.     

蜂窝网无线定位新技术

首先说明移动电话用户紧急情况下需要无线定位业务。接着简述无线定位的几种常用技术,并分别说明时分多址和码分多址两类蜂窝网所用无线定位技术的情况。最后提到无线定位的误差来源。     

Design and Dimensioning of a WDM Mesh Network to Groom Dynamically Varying Traffic

In this paper, we address the traffic grooming problem in WDM mesh networks when the offered traffic is characterized by a set of traffic matrices—a variant of dynamically changing traffic. We justify the need to address this problem in mesh networks and also argue for the validity of our approach to solve this problem. Our primary objective is to design the network in terms of the number of wavelengths and transceivers required to support any offered traffic matrix. We provide a simple and generic framework to minimize the number of transceivers needed in the network. Simulation results have been presented in contrast with a possible approach, to enable comparison with our solution strategy. An ILP formulation of our approach is also presented.     

Lagrangean Based Methods for Solving Large-Scale Cellular Network Design Problems

The cellular network design (CND) problem is formulated as a comprehensive linear mixed integer programming model integrating the base station location (BSL) problem, the frequency channel assignment (FCA) problem and the topological network design (TND) problem. A solution algorithm based on Lagrangean relaxation is proposed for solving this complex cellular network design problem. Pursuing the optimum solution through exact algorithms to this problem appears to be unrealistic considering the large scale nature and NP-hardness of the problem. Therefore, the solution algorithm strategy consists in computing effective lower and upper bounds for the problem. Lower bounds are evaluated through a Lagrangean relaxation technique and subgradient method. A Lagrangean heuristic is developed to compute upper bounds based on the Lagrangean solution. The bounds are improved through a customized branch and bound algorithm which takes in account specific knowledge of the problem to improve its efficiency. Thirty two random test instances are solved using the proposed algorithm and the CPLEX optimization package. The results show that the duality gap is excessive, so it cannot guarantee the quality of the solution. However, the proposed algorithm provides optimal or near optimal solutions for the problem instances for which CPLEX also provides the optimal solution. It further suggests that the proposed algorithm provides optimal or near optimal solutions for the other instances too. Finally, the results demonstrate that the proposed algorithm is superior to CPLEX as a solution approach for the CND problem.     

一种快速蜂窝多跳网路由算法

本文提出了一种适用于蜂窝多跳网的路由算法.该算法充分考虑了蜂窝多跳小区以基站为中心的特点.将传统的分布式路由方式改为基站统一为各节点提供路由的集中处理方式,并定义了一套与之适应的信令.由于采用了集中的处理方式,在新方法中,基站能够通过处理和维护路由过程中所得到的信息,逐步获取小区的拓扑结构,提高路由的效率.仿真结果表明,相比于现有方法,本文提出的算法在寻路的时间上大大缩短,寻路的质量也有一定提高.     

基于NS2的移动自组混合网络模拟平台研究

提出了一种统一的移动自组混合网络模型,并在NS2中实现了该网络模型.首先对NS2中的核心模块进行了扩展,使其支持移动节点的多模通信和多信道;其次,在NS2中添加了新的移动网关选取模块.在扩展后的NS2平台上,通过模拟和比较成组位置更新和传统位置更新,验证了仿真平台的正确性和合理性.研究成果为基于蜂窝Ad hoc混合网络结构的协议研究提供了一个较通用的仿真平台.     

蜂房式无线数据网及其应用

本文对无线数据网的体系和蜂房式无线数据网络系统的构成作了简要的分析，指出了蜂房式无线数据网络的主要关键性技术、特点及应用领域。     

Performance of Channel Carrying for Handoff in a DCA Cellular Network

Channel carrying allows a mobile station to continue the use of its currently occupied channel when it hands off to a new cell. Since in a dynamic channel assignment (DCA) system, generally, any channel can be usedby any cell, channel carrying can be more easily implemented than in a fixed channel assignment (FCA) system which supports channel carrying through borrowing channels or extending channel reuse distance. Therefore, this paperinvestigates different channel carrying strategies maybe used in the distributed timid DCA scheme with the seamless handoff policy (DCA-DT/SLH), namely, channel carrying first (CCF) and channel carrying last (CCL). This study shows that (1) CCL generally outperforms CCF; (2) in DCA-DT/SLH without channel carrying,handoff calls may suffer higher dropping probabilities than new calls if no priority is given to handoff calls while channel carrying can easily avoidsuch undesirable situation; and (3) channel carrying in DCA-DT/SLH is comparableand even better than the guard channel (GC) in FCA and can also slightly improvethe performance of GC in DCA-DT/SLH.     

WCDMA网络规模预测方法分析

WCDMA网络规划包括无线网络、核心网络、传输网络、支撑系统等多方面的规划，是一个比较复杂的工程体系。现提出了一种新的WCDMA无线网络规划方案，并与当前其它的WCDMA无线网络规划方案进行了比较。     

一种蜂窝网中的跟踪算法

移动台定位技术是未来移动通信的方向。为了实现动态连续定位跟踪服务和提高定位精度,提出了一种在蜂窝网络中非视距（NLOS,Non-line of Sight）环境下对移动台（MS,Mobile Station）的定位跟踪算法。在用经典定位算法获得定位初始估计值后,利用卡尔曼滤波器对移动台的初始位置估计值进行修正,并配合检测门限对移动台进行跟踪。仿真结果表明,该跟踪算法能够实现对移动台动态定位跟踪,并且取得了良好的效果。