基于场景的WLAN网络无线优化策略

作为四网协同的重要组成部分,WLAN网络优化越来越受到重视.本文介绍了一种基于场景的WLAN网络无线优化策略,从8大WLAN热点场景的需求出发,梳理了覆盖、容量、质量等方面的优化思路,给出具有针对性的优化措施及实例.     

WLAN网络规划设计

随着WLAN网络的日益普及,网络规划的重要性越来越突出.本文从调研及勘查、覆盖设计、频率规划、容量规划、网络优化几方面对无线局域网的规划进行介绍和分析,为WLAN网络的部署提供参考.     

全业务运营下宽带无线接入网络建设纵横谈

在全业务运营环境下,移动互联网业务正在成为市场发展的主要抓手。宽带无线接入作为移动互联网的关键环节正面临诸多技术、经济问题。WLAN和Femto是当前重要的宽带无线接入技术,通过对两种技术的比较以及系统、覆盖总体方案的设计,从频率规划和扰码规划、无线接入点选择、网络性能测试等不同角度对WLAN和Femto网络建设中的重要问题进行分析,最后对我国宽带无线接入网建设中需注意的问题给出简要结论。     

CDMA网络中的容量与导频污染优化

容量与导频污染优化是CDMA网络优化中的两个关键问题,通过覆盖优化、功率控制、接入控制可实现网络容量的提升,而结合调整基站配置和无线参数来消除导频污染也能进一步改善CDMA网络性能。     

对WLAN无线网络规划及优化技术的分析

经过理论分析和OPNET仿真比较所提出的针对WLAN无线接入网络的规划从传播预测及覆盖设计方面研究覆盖规划、分析研究基于DCF协议的容量规划以及干扰分析和信道优化配置等方法,能有效的降低数据包的碰撞概率,从而降低了时延,增加了系统吞吐率、和网络容量.提出的基于RTS/CTS机制改进的退避算法是对基于CSMA/CA协议的DCF性能的分析和改进,并得出的饱和条件下系统归一化吞吐率、丢包率、网络延时等性能,以此指标用来指导实际吞吐量的估算和网络容量规划.     

电信级WLAN网络建设方案的讨论

本文从几个方面对WLAN网络建设的建设方案做了详细阐述,先从WLAN网络对各电信运营商的战略定位,接着从AC+Thin AP的建设方式,无线的频点规划,无线容量与覆盖的规划设计以及VLAN在WLAN网络中的应用等多个方面,对电信级WLAN网络各个环节的建设方案进行了详细剖析.为运营商的WLAN建设方案提供参考意见.     

WLAN网络优化设计

与有线局域网相比，WLAN的技术优势是可以在热点地区为用户提供无线宽带业务，在WLAN网络优化设计方面值得探讨和研究的问题很多，这里主要针对WLAN的类型选择，无线组网，覆盖设计，容量设计，频率规划，查勘测试等方面进行论述。     

高校宿舍区网络设计与分析

信息化的不断发展对高校宿舍区网络建设提出了更高的要求,现有网络存在接入带宽低、WLAN覆盖薄、账号管理复杂、无法满足新型应用等诸多问题.本文结合中国电信股份有限公司上海分公司“城市光网”建设,分析了多种有线、无线组网技术,讨论了新一代高校宿舍区网络设计方案.     

WLAN与电信网络结合

无线局域网是计算机网络技术和无线通信技术相结合的产物,具有可移动、便于组网、低成本、扩展能力强等优点,同时也具有其覆盖区域较小的缺点,需与现有网络相结合.由于WLAN解决了移动网络数据传输率低的问题,同时移动网络弥补了WLAN覆盖范围小的缺点,实现了优势互补,因此与移动网络的结合是WLAN发展的重要方向.     

电信级WLAN网络面临的问题研究

随着智能终端的不断普及以及运营商的大力推动,WLAN对于分流无线数据流量起到了越来越重要的作用,WLAN成为运营商无线宽带业务中不可或缺的组成部分。作为一种无线接入技术,WLAN以其灵活性、移动性的特点越来越为广大公众接受。然而,在各大运营商加紧推进WLAN建设的同时,WLAN网络在建设以及使用过程中也出现了各种各样的问题。文章结合国内三大运营商,通过分析当前电信级WLAN网络现状,从用户认证不简介、AP之间干扰严重、故障排查定位困难这三个方面进行了详细的分析,是WLAN网络的规划与优化的基础。     

Immune optimization algorithm for solving vertical handoff decision problem in heterogeneous wireless network

In heterogeneous wireless network environment, wireless local area network (WLAN) is usually deployed within the coverage of a cellular network to provide users with the convenience of seamless roaming among heterogeneous wireless access networks. Vertical handoffs between the WLAN and the cellular network maybe occur frequently. As for the vertical handoff performance, there is a critical requirement for developing algorithms for connection management and optimal resource allocation for seamless mobility. In this paper, we develop a mathematical model for vertical handoff decision problem, and propose a multi-objective optimization immune algorithm-based vertical handoff decision scheme. The proposed scheme can enable a wireless access network not only to balance the overall load among all base stations and access points but also maximize the collective battery lifetime of mobile terminals. Results based on a detailed performance evaluation study are also presented here to demonstrate the efficacy of the proposed scheme.     

高校WLAN建设规划探讨

无线局域网(WLAN)是一种高新的网络模式,与目前有线宽带形成一种互补,能够为网络用户提供更为方便快捷的网络接入。结合高校的综合情况,包括教学区、各栋寝室的情况,规划、设计,建立了高校无线局域网。具体实践表明无线局域网解决了高校的无线网络覆盖问题,能为高校提供网络服务,加快高校信息化程度建设。同时,在建设过程中的一些经验交流,也能为高校的WLAN建设提供一定的参考。     

Throughput analysis of a CSMA based WLAN with successive interference cancellation under Rayleigh fading and shadowing

In this paper, we consider a carrier sense multiple access based wireless local area network (WLAN) with a successive interference cancellation (SIC) technique. We develop an analytical model to compute the average throughput of a user in a WLAN with the SIC technique in presence of path loss, Rayleigh fading and log-normal shadowing. We then validate the model via simulation. By means of the developed analytical model, we compute the average throughput of a user in WLAN systems without and with the SIC technique and evaluate the throughput gain provided by the SIC technique. We find that the throughput gain provided by the SIC technique is significant. However, the throughput gain varies significantly depending on the parameters of network and wireless channel. We find that the throughput gain provided by the SIC technique increases with increasing the number of users in WLAN, medium access rate of the users and the variance in shadowing and it decreases with increasing the data transmission rate. We also investigate the effect of the decoding capability of the SIC technique on the throughput performance. We find that throughputs obtained with decoding capability of 2 and 3 packets are very close.     

Heterogeneous uncoordinated deployment of WLANs: an evolving problem for current and future Wi‐Fi access

This article addresses the problem of uncoordinated heterogeneous deployment of 802.11 wireless local area networks (WLANs). It is expected that such deployments by different WLAN owners and WiFi providers will become a challenging problem that limits the network performance and quality of service of wireless users. We present results of a real case study that show a need for coordination among WLAN devices in order to avoid current and future problems. We provide potential solution directions. A special focus is given to channel assignment and coordinated channel access problems. Our results show that a new paradigm for designing WLAN devices seems to be crucial. Copyright © 2012 John Wiley & Sons, Ltd.     

Interoperability criteria, mechanisms, and evaluation of system performance for transparently interoperating WLAN and UMTS-HSDPA networks

The main challenge in the development of future wireless communication systems is to provide users with a wide range of services across different radio access technologies through a single mobile terminal, while maintaining the minimum QoS requirements, and ideally with no limits on the coverage area, mobility or radio conditions. Thus, the need for seamless interworking between heterogeneous wireless communication systems consisting of multiple radio access technologies and overlapping networks emerges. In this article we address the main issues that arise while implementing the interoperability mechanisms between two different radio access networks, with emphasis on UMTS-HSDPA and WLAN (HIPERLAN/2). Two interoperability mechanisms are introduced and described in detail: initial user assignment (optimal network selection) and intersystem handover. Both mechanisms are activated via the optimization of a suitably defined cost function which takes into account all the appropriate system level parameters that trigger the interoperability process. Finally, we investigate the overall performance of the proposed mechanisms by means of a software simulation platform. A number of simulations have been carried out in order to demonstrate the performance enhancements achieved by the proposed mechanisms in terms of unsatisfied users, dropped handovers, and system throughput.     

Context Aware Inter-BSS Handoff in IEEE 802.11 Networks: Efficient Resource Utilization and Performance Improvement

IEEE 802.11 has become very popular wireless technology to offer high speed Internet access at public places called the ‘Hot-Spots’. This has enabled users to access multimedia and other real time applications using wireless local area networks (WLAN). In IEEE 802.11 WLAN technology, associations between a mobile station and an access point (AP) is controlled by the mobile station, allowing the station to select an AP with the strongest signal in terms of either ‘Received Signal Strength Identifier’ or ‘Signal to Interference and Noise Ratio’. In real time scenarios, the traffic patterns of mobile users are dynamic in nature. This leads to a situation where the traffic loads on the APs are unevenly distributed in the WLAN. Such imbalance in traffic load causes severe degradation in performance of the applications running on the mobile stations associated with the overloaded APs. In this paper, we propose a scheme which dynamically improves the performance of the overloaded APs by handing off some of its associated stations to nearby APs. This handoff decision is taken by an AP in assistance with the mobile stations. The effectiveness of the load distribution through dynamic hand-over in a WLAN is analyzed through theoretical analysis. Simulation results show the overall improvements in terms of delay, throughput and number of stations that an AP can support. The performance improvement in the proposed scheme is also justified through the results obtained from a IEEE 802.11 WLAN testbed.     

Saturation throughput analysis of a carrier sensing based MU-MIMO MAC protocol in a WLAN under fading and shadowing

In wireless local area networks (WLANs), the traditional carrier sense multiple access with collision avoidance (CSMA/CA) medium access control (MAC) protocol cannot use the full benefits from multiuser multiple-input multiple-output (MU-MIMO) technique due to random medium access of the users. In this paper, we propose a carrier sensing based MAC protocol for a MU-MIMO based WLAN with full utilization of MU-MIMO technique. By modeling the WLAN system under the proposed MAC protocol as a discrete time Markov chain, we develop an analytical model for computing the saturation throughput in presence of path loss, Rayleigh fading and log-normal shadowing. The analytical model is then validated via simulation. By means of numerical and simulation results, we demonstrate that the proposed MAC protocol significantly improves throughput performance than the traditional CSMA/CA MAC protocol. Further, we compare the performance of the proposed MAC protocol with a MU-MIMO MAC protocol called Uni-MUMAC protocol and find that the proposed MAC protocol performs better than the Uni-MUMAC protocol. We also explore the effect of some of the network and wireless channel parameters on the performance of the proposed MAC protocol.

     

An Overview of WLAN Performance,Some Important Case-Scenarios and Their Associated Models

The study of the 802.11 standard has been very intense for more than a decade now. Several works have striven at understanding its performance, even in the simplest topology of a wireless local area network (WLAN) with a single access point. The present survey is an effort to classify and present the enormous literature on the subject into several important case-scenarios, and summarizes the current understanding of WLAN performance. The resulting performance and associated models are discussed (and sometimes extended) and simulation results are used to illustrate them. We also highlight interesting open research problems that we believe the community should address.     

提升EDGE网络性能的无线网络优化方法探讨

通过对影响EDGE性能的关键因素分析,从无线网络优化角度出发,在网络资源、无线环境优化、初始接入编码设置和新功能应用等方面提出了提升EDGE性能的优化方法,提高用户感知度。