传输PTN承载对无线接入网质量影响问题的分析

在传输PTN承栽无线网BBU的情况下,为提前发现传输接入网络隐患,采用分段界定法,发现端口弱光、环路弱光、超大环路、CRC校验等问题对无线接入质量有较大影响。针对性开展预防性维护工作,提升无线网络接入质量,有效改善用户感知。

无线接入宽带网中的安全通信

1 引言移动通信在过去二十年中获得了飞速发展,已成为现代通信中一个极为重要的领域。国际互连网的发展以及随之而来的网络信息时代要求移动通信系统能够提供多媒体业务。因此,从九十年代中期开始,人们致力于第三代移动通信系统的开发和研究,以提供移动多媒体通信能力并获得与固定通信网相当的业务质量。

无线接入宽带网的设计与实现

无线局域网的快速发展,已经成为近年来最惹人关注的通信产品,本文主要介绍了无线局域网的网络结构、技术特点和工作原理,并针对采用SIM卡的上网方式进行了全面较深入的讨论。

校园无线接入方案之我见

互联网带来的科技革命影响不仅仅是在工业发展中,也带来了教育信息化的革命,随着笔记本技术的发展,笔记本电脑不再是奢侈品,现在已经成为校园里的常见的学习工具之一,无线网络在校园中的应用在校园信息化建设中起到了巨大的促进作用,对大学而言,传统的无线网接入方式不能满足电化授课需要,也不能满足师生在图书馆、寝室都需要无线网使用的必要,因此,建立高效无线网接入是教育信息化建设的必需品。

FTTR场景下空间复用与速率联合优化

随着网络技术的飞速发展,用户对家庭场景内网络体验的要求日益增加。FTTR能够在一定程度上解决无线网络连接不稳定的问题。在FTTR架构基础上,介绍了集中式光无线网接入架构,探讨了下一代Wi-Fi协同空间复用技术与速率控制的主要原理,并对当前面临的挑战以及未来的研究方向进行了分析和展望。

MAC isolation to realize effective management in public wireless LAN

This paper describes how to use medium access control (MAC) isolation to enhance management performance in public wireless LAN (PWLAN). To comply with the IEEE 802.11 standards, a scheme to implement MAC isolation in WLAN access points by re-designing the Distribution_Service component of the MAC state machine is proposed. A variable named dotl 1 Isolation is defined to determine whether the MAC level communication between wireless stations in the same BSS is permitted or not. Finally, a design solution based on MPC860 hardware and embedded Linux software for PWLAN access point is specified. The simulation results of MAC isolation for PWLAN show that the proposed scheme is feasible and effective.

深圳地铁9号线公用移动电话引入方案分析

基于地铁通信的特点,为促进公众移动电话系统与地铁专用通信系统更好的结合及合理布置。本文采用现场调研勘察,结合相关通信标准要求,对深圳地铁9号线公用移动电话引入设计方案进行研究。

Qo E-based resource allocation protocols in cognitive OFDMA network with hybrid model

A resource allocation protocol is presented in an orthogonal frequency division multiple access （OFDMA） cognitive radio （CR） network with a hybrid model which combines overlay and underlay models. Without disrupting the primary user （PU） transmissions, the overlay model allows the secondary user （SU） to utilize opportunistically the idle sub-channels; the underlay model allows the SU to occupy the same sub-channels with PU. The proposed protocols are designed for maximizing the quality of experience （QoE） of CR users and switching dynamically between the overlay and underlay models. QoE is measured by the mean opinion score （MOS） rather than simply fulfilling the physical and medium access control （MAC） layer requirements. The simulations considering the file transfer and video stream services show that the proposed resource allocation strategy is spectrum efficient.

Performance enhancement of IEEE 802.11 distributed coordination function for MANET

The medium access control (MAC) issue was discussed in mobile Ad Hoc networks (MANETs). Based on the IEEE 802.11 MAC protocol, this paper proposed two schemes, the forward-packet-first (FPF) scheme based on the adaptive backoff contention window and multihop forward chain transmission by invitation (MFCTI) scheme. In the FPF scheme, the contention window was adjusted adaptively according to the traffic priority. Route information and the broadcast characteristic of radio were utilized in MFCTI scheme. The performance of these schemes was studied in multihop environments by simulations. The results showed that the proposed schemes could improve the network throughput, reduce the end-to-end average delay, and mitigate local congestion effectively. Another attractive feature was that the schemes could be implemented with minor modifications to the IEEE 802.11 MAC.

Dynamic Target Wireless Network Selection Technique Using Fuzzy Linguistic Variables

Even though various wireless Net- work Access Technologies （NATs） with dif- ferent specifications and applications have been developed in the recent years, no single wireless technology alone can satisfy the any- time, anywhere, and any service wire- less-access needs of mobile users. A real seamless wireless mobile environment is only realized by considering vertical and horizontal handoffs together. One of the major design issues in heterogeneous wireless networks is the support of Vertical Handoff （VHO）. VHO occurs when a multi-interface enabled mobile terminal changes its Point of Attachment （PoA） from one type of wireless access technology to another, while maintaining an active session. In this paper we present a novel multi-criteria VHO algorithm, which chooses the target NAT based on several factors such as user preferences, system parameters, and traf- tic-types with varying Quality of Service （QoS） requirements. Two modules i.e., VHO Neces- sity Estimation （VHONE） module and target NAT selection module, are designed. Both modules utilize several ＂weighted＂ users＇ and system＇s parameters. To improve the robust- ness of the proposed algorithm, the weighting system is designed based on the concept of fuzzy linguistic variables.

第四代移动通信技术(4G)在地铁中的应用

随着4G牌照对各运营商的发放,运营商移动网络的不断建设,网络覆盖的日益完善,移动用户对通信质量的要求越来越高,目前将4G引入地铁已经势在必行。介绍了地铁内移动通信信号的覆盖方式、链路预算及系统间干扰分析。结合地铁的特点,4G系统可在2G、3G的基础上共用一套天馈系统,既节约投资又减少了工程难度;在场强设计时,应结合信号的覆盖方式及特点采取抗干扰措施。

Design and development of WLAN access point based on Bluetooth and uClinux

This paper describes the design and development of a wireless LAN (WLAN) access point based on Bluetooth and uClinux. To make the best use of high-speed serial communication capability, several methods such as modifying baud-rate of serial port driver, utilizing buffer area and adding flow-control were adopted. After analysis of scheduling and interruption handling, modifying the timer's parameters was put forward as a method to control the timer interrupt. In this way, data throughput and system stability were enhanced. Meanwhile, migration of the Bluetooth protocol stack was detailed and some successful applications of LAN access point were presented.

Tree-Based Proactive Routing Protocol for Wireless Mesh Network

Wireless Mesh Network （WMN） is seen as an effective Intemet access solution for dynamic wireless applications. For the low mobility of mesh routers in WMN, the backbone topography can be effectively maintained by proactive routing protocol. Pre-proposals like Tree Based Routing （TBR） protocol and Root Driven Routing （RDR） protocol are so centralized that they make the gateway becorre a bottleneck which severely restricts the network performance. We proposed an Optimized Tree-based Routing （OTR） protocol that logically separated the proactive tree into pieces. Route is partly computed by the branches instead of root. We also discussed the operation of multipie Intemet gateways which is a main issue in WMN. The new proposal lightens the load in root, reduces the overhead and improves the throughput. Numerical analysis and simulation results confirm that the perforrmnce of WMN is improved and OTR is more suitable for large scale WMN.

Invited Paper: The Audacity of Fiber-Wireless(FiWi) Networks: Revisited for Clouds and Cloudlets

There is a growing awareness among industry players of reaping the benefits of mobile-cloud convergence by extending today's unmodified cloud to a decentralized two-level cloud-cloudlet architecture based on emerging mobile-edge computing(MEC) capabilities. In light of future 5G mobile networks moving toward decentralization based on cloudlets, intelligent base stations, and MEC, the inherent distributed processing and storage capabilities of radio-and-fiber(R&F) networks may be exploited for new applications, e.g., cognitive assistance, augmented reality, or cloud robotics. In this paper, we first revisit fiber-wireless(Fi Wi) networks in the context of conventional clouds and emerging cloudlets, thereby highlighting the limitations of conventional radio-overfiber(Ro F) networks such as China Mobile's centralized cloud radio access network(C-RAN) to meet the aforementioned trends. Furthermore, we pay close attention to the specific design challenges of data center networks and revisit our switchless arrayedwaveguide grating(AWG) based network with efficient support of east-west flows and enhanced scalability.

A Frameless Network Architecture for the Way Forward of C-RAN

The key technologies involved in the evolution of the Cloud-based Radio Access Network(C-RAN) are discussed in this paper. Taking the Frameless Network Architecture(FNA) as a starting point, a cell-lessbased network topology for a multi-tier Heterogeneous Network(Het Net) and ultra-dense network is proposed. The FNA network topology modeling is researched with centralized processing and distributed antenna deployments. The Antenna Element(AE) is released as a new dimensional radio resource that is included in the centralized Radio Resource Management(RRM) processes. This contributes to the on-demand user-centric serving-set associations with cell-edge effect elimination. The Control Plane(CP) and User Plane(UP) separation and adaptation are introduced for energy efficiency improvements. The centralized RRM and different optimization goals are discussed for fully exploring the merits from the centralized computing of C-RAN. Considering the complexity, near-optimal approaches for specific users' Quality-of-Service(Qo S) requirements are addressed. Finally, based on the research highlighted above, the way forward of C-RAN evolution is discussed.

Cross-Layer Framework for Fine-Grained Channel Access in Next Generation High-Density Wi Fi Networks

Densely deployed Wi Fi networks will play a crucial role in providing the capacity for next generation mobile internet. However, due to increasing interference, overlapped channels in Wi Fi networks and throughput efficiency degradation, densely deployed Wi Fi networks is not a guarantee to obtain higher throughput. An emergent challenge is how to effi ciently utilize scarce spectrum resources, by matching physical layer resources to traffi c demand. In this aspect, access control allocation strategies play a pivotal role but remain too coarse-grained. As a solution, this research proposes a flexible framework for fine-grained channel width adaptation and multi-channel access in Wi Fi networks. This approach, named SFCA(Subcarrier Fine-grained Channel Access), adopts DOFDM(Discontinuous Orthogonal Frequency Division Multiplexing) at the PHY layer. It allocates the frequency resource with a subcarrier granularity, which facilitates the channel width adaptation for multi-channel access and thus brings more fl exibility and higher frequency efficiency. The MAC layer uses a frequencytime domain backoff scheme, which combines the popular time-domain BEB scheme with a frequency-domain backoff to decrease access collision, resulting in higher access probability for the contending nodes. SFCA is compared with FICA(an established access scheme)showing significant outperformance. Finally we present results for next generation 802.11 ac Wi Fi networks.

Dynamic Resource Allocation in TDD-Based Heterogeneous Cloud Radio Access Networks

To fulfill the explosive growth of network capacity, fifth generation(5G) standard has captured the attention and imagination of researchers and engineers around the world. In particular, heterogeneous cloud radio access network(H-CRAN), as a promising network paradigm in 5G system, is a hot research topic in recent years. However, the densely deployment of RRHs in H-CRAN leads to downlink/uplink traffic asymmetry and severe inter-cell interference which could seriously impair the network throughput and resource utilization. To simultaneously solve these two problems, we proposed a dynamic resource allocation(DRA) scheme for H-CRAN in TDD mode. Firstly, we design a clustering algorithm to group the RRHs into different sets. Secondly, we adopt coordinated multipoint technology to eliminate the interference in each set. Finally, we formulate the joint frame structure, power and subcarrier selection problem as a mixed strategy noncooperative game. The simulation results are presented to validate the effectiveness of our proposed algorithm by compared with the existing work.

A SDN-Based Energy Saving Strategy in Wireless Access Networks

This paper investigates on the base stations(BSs) sleeping control and energy saving in wireless network. The objective is to find the sleeping control and energy saving configuration between total power consumption and average video's quality. On the Software Defined Network(SDN) access network architecture, a type of sleeping control and active BSs' optimal transmitting time strategy is considered, the BS sleeps when there is no active users, and wakes up after a period of vacation time. In this paper, we study the active users grouping strategy, In order to spare more BSs into sleeping mode. Then this paper proposes an active BS transmitting time optimal strategy according to the users' Qo S. In the proposed strategy, the active BSs' transmitting time is minimized in order to save energy. This paper employs the mixed integer-programming model to present this optimization problem. Then we utilized a novel algorithm to save the energy in access networks and also meet the Qo S requirements. Both the analytical and simulation results show that the algorithm can effectively save energy in the access network BSs.

A 5G Virtualized RAN Based on NO Stack

The virtualized radio access network(v RAN) could implement virtualized baseband functions on general-purpose platforms and expand the processing capacity of the radio access network(RAN) significantly.In this paper,a Not Only Stack(NO Stack) based vR AN is proposed to be employed in the fifth generation(5G) mobile communication system.It adopts advanced virtualization technologies to maintain flexible and sustainable.The baseband processing and storage resources should be sliced and orchestrated agilely to support multi radio access technology(multiRAT) .Also it is analyzed and demonstrated by different use cases to validate the benefits.The proposed v RAN reduces signaling overheads and service response time in the bearer establishment procedure.Concluded from the analyses and demonstrations,the NO Stack based v RAN could support multi-RAT convergence and flexible networking effectively.