基于分布式动态功率控制的WLAN/WPAN自身干扰解决算法

文中提出的分布式动态功率控制(DDPC)算法能够在高密度WLAN/WPAN环境下大大提高每个用户的吞吐量,解决由于有限的信道所带来的自身干扰问题,尤其在变化不均匀的通信量条件下.仿真表明给定任意的通信负载分布及原始信道分配,算法会快速收敛到平衡状态,整个网络的吞吐量得到了很大的提高.该算法能够根据信道的使用状态自适应的改变算法启动门限,并且只通过AP自身完成动态信道分配算法,真正解决了高密度WLAN/WPAN环境下的自身干扰问题,简单有效并有很高的实用价值.     

TD-LTE与WLAN干扰测试分析案例

根据我国频谱规划,在2.4 GHz频点处将出现TD-LTE室内覆盖系统与WLAN系统共存情况。从理论上分析室内环境中TD-LTE与WLAN系统共存场景下存在的干扰分析及隔离要求;通过对TD-LTE室内覆盖系统与WLAN系统共存场景下的实例测试分析,研究TD-LTE系统与WLAN系统在室内覆盖共存场景的干扰影响,并分析TD-LTE室内覆盖系统与WLAN系统共存场景时的隔离要求;给出在室内覆盖系统中TD-LTE和WLAN共存部署的建议,为今后TDLTE室内覆盖系统与WLAN系统共存建设提供依据和指导。     

一种TD-LTE混合干扰分析及解决系统

TD-LTE网络采用同频段组网,尽管提高频谱利用效率但相邻小区间干扰比较严重,因而良好的覆盖和干扰控制对网络性能意义重大。传统的干扰排查针对单一干扰类型的杂散干扰、阻塞干扰、谐波干扰等展开,对实际场景中由多种干扰源混合构成的混合干扰研究较少。本文围绕TD-LTE网络混合干扰,提出一个集分析排查与解决验证于一身的系统,旨在帮助优化人员快速定位主要干扰源并能有效处理解决问题。     

关于WLAN覆盖的研究

针对目前WLAN建设中普遍存在的覆盖范围小、覆盖信号弱及覆盖不连续等覆盖问题,通过采用衰减因子模型对2.4 GHz频段进行链路预算分析,得出室内独立型AP及室内分布型AP、室外独立型AP等3种不同覆盖方式下的WLAN理论覆盖范围。根据不同覆盖方式的覆盖范围,结合不同的应用场景,提出了AP密集覆盖和室外AP+高增益定向天线等2种加强WLAN覆盖的措施,为WLAN覆盖提供了有效的解决思路。     

基于联合优化的WLAN动态频率选择改进算法

现有的动态频率选择机制有效降低了网络间的干扰,但仅考虑了物理层的干扰最小。无线局域网网络密度越来越高,支持的业务越来越丰富,不同的业务传输所需要的带宽、允许的时延均不相同。为了有效提升业务传输效率和网络容量,提出了一种改进的动态频率选择算法。具体为:接入点将站点的信号接收质量、载干比、占用信道时间系数和业务优先级作为优化问题的特征参数集,综合考虑多个站点上报的信道测量报告,利用凸优化理论以吞吐量最优为目标联合进行优化,选定接入点的工作信道。最后,结合实际的场景图,仿真对比了动态频率选择改进算法和未采用动态频率的性能,结果显示改进算法使干扰区域的吞吐量增加了10倍,能明显降低WLAN网络的干扰,提升WLAN的业务传输效率,可广泛应用于WLAN的产品设计。     

TDD模式下无小区大规模MIMO系统的导频干扰抑制

为了缓解无小区大规模MIMO系统的导频干扰、提高系统性能，提出了一种综合导频复用、AP选择和功率控制的导频干扰抑制策略。首先，提出了基于用户距离排序的导频分配，合理地避免了两个距离较近的用户复用导频，以减少导频干扰的影响。然后，通过分析系统吞吐量表达式中的影响因子确定AP选择的标准，只选择对用户的宏分集增益有主要影响的AP作为用户的服务AP。最后，提出了一种改进的最大最小功率控制算法，提高系统平均吞吐量。仿真结果显示，提出的导频干扰抑制策略有效地减轻了导频干扰带来的性能损失。     

室外场景WLAN无线参数优化方案研究

以室外CBD商圈热点为优化对象,介绍了一种室外场景的WLAN无线参数优化解决方案。该方案采用避轻就重的思路,通过AP信道隔离、功率调整以及优化AP空口资源,达到解决室外场景下同频干扰及容量受限问题的目的。     

SSA-UWB对IEEE 802.11A WLAN系统的干扰研究

认知技术在无线通信系统频谱利用和解决系统干扰中的作用越来越受到关注.就软频谱适应超宽带(SSA-UWB)对于802.11a WLAN的干扰进行了研究,并基于TG1/8研究组报告中UWB与WLAN干扰研究的场景进行了全面的仿真.从仿真结果可以看到,干扰与距离、超宽带终端分布、环境等因素有关.所提出的SSA-UWB频谱,在满足FCC的要求下能够有效的规避对802.11a WLAN系统的干扰.     

基于MR数据TD-LTE上行干扰分析方法研究

TD-LTE上行干扰直接影响系统的上行吞吐量以及接通率.通过对上行干扰特征以及MR数据内指标进行分析研究,提出基于测量报告的上行干扰分析方法,实现上行干扰及干扰源的精确定位,进而缩小上行干扰排查范围,对干扰源针对性地进行排查.     

考虑业务优先级的多信道CRANET合作动态功率控制

针对多信道认知自组织网络(CRANET)中不同业务接人类型的优先级对次用户(SU)发射功率的影响,设计了次用户间业务传输的优先级感知因子,考虑到对主用户系统产生的累积干扰量约束,采用微分博弈建立了合作动态功率控制模型(CoDPCM),获得在总联盟下的合作动态功率控制最优解,同时,考虑到自私次用户的非合作性,建立了非合作动态功率控制模型(NoCoDPCM),获得了反馈Nash(纳什)均衡解,并从理论上进行了性能比较.仿真结果表明,与非合作动态功率控制模型相比,合作动态功率控制模型在发射功率、支付量和系统总体吞吐量等方面表现出较好性能.     

Power-Efficient Spatial Reusable Channel Assignment Scheme in WLAN Mesh Networks

Interference has strong effect on the available bandwidth of wireless local area network (WLAN) based mesh networks. The channel assignment problem for multi-radio multi-channel multihop WLAN mesh networks is complex NP-hard, and channel assignment, routing and power control are tightly coupled. To mitigate the co-channel interference and improve capacity in multi-channel and multi-interface WLAN mesh networks, a power-efficient spatial reusable channel assignment scheme is proposed, which considers both channel diversity and spatial reusability to reduce co-channel interference by joint adjusting channel, transmission power and routing. In order to assign channel appropriately, an efficient power control scheme and a simple heuristic algorithm is introduced to achieve this objective, which adjust the channel and power level of each radio according to the current channel conditions so as to increase the opportunity of channel spatial reusability. The proposed channel assignment scheme also takes load, capacity and interference of links into consideration. Simulation results show the effectiveness of our approach and demonstrate that the proposed scheme can get better performance than other approaches in terms of throughput, blocking ratio, energy consumption and end-to-end delay.     

Vertical handoff algorithm in heterogeneous networks for reducing interference

A vertical handoff decision algorithm in heterogeneous networks composed of CDMA Cell Networks (CN) and Wireless Local Area Network (WLAN) is proposed to minimize the total interference in CDMA. The scope of WLAN is determined by minimizing interference and each communicating node shall handoff to WLAN as soon as it enters the scope. We first propose a model for heterogeneous networks, and based on it we obtain the close-form expression of interference. In order to minimize interference, we use simulation annealing method to get the WLAN radius, which is called basic algorithm. In order to reduce the interference further, we improve the basic and get the enhanced algorithm. Through numerical computing, we analyze the interference in condition of different call arrive rates, and results show that the enhanced can reduce interference more greatly than the basic.     

一种基于SDPA算法的绿色Wi-Fi系统设计与实现

目前主流的无线局域网接入点的工作模式以独立接入控制为主,这种工作模式的频率信道固定,发射功率恒定,容易造成功耗和频谱资源的浪费和信道阻塞。本文通过无线控制器(AC)对AP接入用户的智能感知和动态数据分析,设计基于SDPA算法的绿色Wi-Fi系统,实现了AP的功率动态调整及信道的智能选择,有效减少了电磁辐射污染,并提升了频谱使用效率。     

An efficient resource optimization scheme for D2D communication

With the rapid development of wireless technologies, wireless access networks have entered their Fifth-Generation (5G) system phase. The heterogeneous and complex nature of a 5G system, with its numerous technological scenarios, poses significant challenges to wireless resource management, making radio resource optimization an important aspect of Device-to-Device (D2D) communication in such systems. Cellular D2D communication can improve spectrum efficiency, increase system capacity, and reduce base station communication burdens by sharing authorized cell resources; however, can also cause serious interference. Therefore, research focusing on reducing this interference by optimizing the configuration of shared cellular resources has also grown in importance. This paper proposes a novel algorithm to address the problems of co-channel interference and energy efficiency optimization in a long-term evolution network. The proposed algorithm uses the fuzzy clustering method, which employs minimum outage probability to divide D2D users into several groups in order to improve system throughput and reduce interference between users. An efficient power control algorithm based on game theory is also proposed to optimize user transmission power within each group and thereby improve user energy efficiency. Simulation results show that these proposed algorithms can effectively improve system throughput, reduce co-channel interference, and enhance energy efficiency.     

使用对偶分解的MU-CoMP-JT联合资源分配

在MU-Co MP-JT(Multi-User Coordinated Multiple-Points Joint Transmission)联合资源分配问题中,传统的迫零预编码矩阵会使得每根天线发送功率互不相同,当Co MP节点发射功率仅满足总功率约束时性能损失不明显,而当Co MP节点分布在不同的地理位置时将受到单节点功率约束,这势必会降低系统功率利用率。为了进一步提升系统吞吐量,基于对偶分解理论提出了一种联合预编码优化的资源分配算法。该算法以最大化用户权重速率为目标,将原优化问题分解成若干个优化的子问题,不同子问题对应不同接收天线数的联合优化问题。当子信道的发送天线数大于接收天线数时,通过多次迭代计算得到预编码矩阵,并且预编码矩阵会随着拉格朗日因子的变化而变化。仿真结果表明所提联合预编码优化的联合资源分配算法能够明显提升系统吞吐量,且提高天线功率利用效率。     

AC虚拟化技术在WLAN网络中的应用前景分析

本文通过分析WLAN网络建设中核心控制层遇到的问题,探讨AC虚拟化技术的应用.为提高网络资源利用率,提高网络可靠性,减轻运维压力,降低网络大规模建设对机房空间及电源带来的压力寻找解决方案.     

基于跨AC切换实现WLAN快速拨测和拥塞控制策略研究

文章介绍了当前WLAN保障中使用的拨测方法和拥塞控制手段,然后提出了一种基于跨AC切换实现WLAN 拨测和拥塞控制的方法.通过提出一种跨WLAN AC的切换设备,可实现集中控制一个AP快速切换至各个AC进行拨测.利用AP拨测结果和AC日志的双重对比分析方法,对vSwitch下挂AP设备快速批量地割接至容灾AC,最大限度...     

高密度WLAN环境下传输功率控制算法的研究

提出了一种新的传输功率控制算法（TPC），该算法能够根据信道的自身干扰情况．自适应的优化算法参数，动态控制AP发射功率，在现有的信道资源下提升系统容量。给出了算法处理过程的描述．并以IEEE802．11b系统为例进行仿真。仿真结果表明：该算法能够实现在高密度、负载不均衡的WLAN环境下大大提高整个系统的吞吐量。     

A Network Coding Scheme to Improve Throughput for IEEE 802.11 WLAN

In IEEE 802.11 infrastructure wireless local area network (WLAN), the communication between any two nodes is relayed by an access point (AP), which becomes the bottleneck of WLAN and severely restricts the overall throughput. It is well known that network coding technique is able to greatly improve the throughput of wireless networks. But, the available coding schemes do not make full advantage of channel capacity due to the fact that they pick at most one packet from each data flow for coding and the picked packets may have a great difference in packet size, wasting some channel capacity. To remedy the problem, in this paper, we propose the coding scheme that combines multiple buffered packets in one flow into a larger packet for coding so that the packets participating in coding have close sizes. We formulate an integer programming problem to find the optimal packet coding, which is solved by an optimal algorithm with relative high time complexity together with a heuristic algorithm with relative low time complexity. Simulation results show that the proposed coding scheme is able to greatly improve the throughput of WLAN and the throughput gain increases with the growth of the number of coding flows.