面向VANETs的服务质量的一种信道分配的新算法

车辆的高速移动,导致频繁地进行呼叫切换,这就使得信道分配成为车联网VANETs( Vehicular Ad Hoc Network)中最受关注的研究热点。为此,提出一种新的信道分配算法,标记为SBC算法。该算法引用信道再使用技术( Channel Reuse Technique)、信道借用( Channel Borrowing),并依据车辆行驶的速度计算发生切换的时间,从而提高服务质量QoS( Quality of Service)。仿真结果表明,提出的SBC算法在呼叫阻塞概率、丢失率和切换时延方面表现良好的性能。     

蜂窝移动通信系统中基于紧凑模式的信道借用指配策略

本文介绍了蜂窝移动通信系统中一种新的动态信道指配策略——基于紧凑模式的信道借用指配策略(CPCB).这种策略不仅具有基于紧凑模式的动态信道指配的优点,而且具有固定信道指配策略中信道借用的优点.作者将新算法在一种普遍采用的49个蜂窝的蜂窝通信网络上进行了仿真,分别对几种均匀和非均匀模式的业务分布情况进行了比较,结果表明:CPCB的系统平均阻塞率低于FCA、BDCL、基于CP的DCA和CPMCB等,而且随着负载的增加,其系统平均阻塞率的增长速率也明显低于上述各种策略.     

无线Mesh网络集中式信道分配算法设计

以集中式无线Mesh网络(WMN)为基础,分析和研究了传统多信道分配算法,并在此基础上提出了以节点优先级和分组为特点的多接口多信道分配算法(Channel Assignment based on Rank of Node and Link group,CAR-NL),该算法结合节点分级和链路负载预期评估机制,通过节点链路分组按级分配信道。通过仿真实验表明,该算法能有效提高无线Mesh网络多业务流并发执行时系统整体吞吐量,并实现较低的丢包率。     

多射频无线mesh网中的联合协作路由与信道分配算法

现有的协作路由算法没有考虑多射频无线mesh网中的信道分配问题.为了给多并发业务流提供更优质的网络服务,本文结合多射频多信道技术和协作通信技术来降低同信道干扰并获得协作分集增益.基于协作通信模块虚拟化的方法,本文将联合协作路由和信道分配问题简化为联合直接路由和信道分配问题,将其建模为一个混合整数线性规划问题,并证明该问题为NP-hard问题.为了解决该问题,提出了一种宽松的联合协作路由选择和信道分配算法(Loose Joint Cooperative Routing and Channel Assignment algorithm,L-JCRCA).仿真实验结果表明,L-JCRCA可以有效提升网络整体吞吐量.     

蜂房移动电话系统中信道指配方式的比较

本文提出了两种新的信道指配方式,即本地最佳动态指配(LODA)方式和具有定向信道锁定能力的信道借用(BDCL)方式。并将它们的性能与固定指配(FA)方式(目前经常运用于一些系统中)和具有信道排序能力的信道借用(BCO)方式(以前的研究表明这种方式具有最低的信道阻塞率)相比较。在一个共有49个小区组成的网络中。在话务量均匀分布和非均匀分布两种情况下进行计算机模拟的结果表明:BDCL 方式的平均呼叫阻塞率总是最低的,在话务量非均匀分布条件上,LODA 方式的性能可以与 BCO 相比拟,但在话务量均匀分布的条件下,LODA 的性能较差。     

分布式网络中基于一致性的信道分配算法

针对实际分布式网络中节点通信受限的特点,设计了基于一致性的拍卖算法CDACA(Consensus-Based Decentralized Auctions for Channel Assignment),实现多段频谱的最优分配.基于本地信息,次用户在CDACA算法的前向拍卖阶段选择一个信道加价投标,空闲信道未分配的主用户在反向拍卖阶段选择一个次用户降价投标;主用户和次用户利用局部通信基于一致性算法确定竞胜标和解决冲突.理论证明了CDACA算法在实际分布式网络中节点通信受限和局部过时信息的情况下能在有限次迭代后收敛到网络效益最优的分配,同时证明了算法在分布式动态网络中也能收敛.仿真结果验证了不同网络拓扑下CDACA算法在收敛速度和频谱效率上的优越性能.     

基于优先级信道预留的快速动态信道分配算法

针对TD-SCDMA系统现有快速动态信道分配算法的不足,提出了一种基于优先级信道预留的快速动态信道分配算法.该算法根据接力切换用户的移动台属性设定不同的优先级,为接力切换呼叫预留信道,结合小分组借用算法,增加了可移动边界动态信道分配(MB DCA)策略的灵活性.仿真结果表明,此算法相对于混合数据速率、小分组借用(MRG,mixed-data rate grouping borrowed)MB DCA算法,实现了VIP和快速移动切换用户的优先接入,有效地降低了切换呼叫的阻塞率,提高了数据业务性能和系统的信道利用率.     

一种基于SIR的DCA方法在无线数据网络中的应用

研究了无线数据网络中的信道分配策略，提出了基于信干比（Signal to Interference Ratio，SIR）的动态信道分配（Dynamic Channel Assignment，DCA），通过判断用户的SIR情况来分配空闲信道，并且建立了无线数据网络的排队论模型。仿真分析了网络的呼叫延迟概率和呼叫延迟超时概率这两个重要的性能指标，结果显示在系统高负载情况下，本文提出的基于SIR的DCA相对于传统的信道分配方法能够获得更好的效果，从而实现了对高负载网络的优化。     

一种超宽带信道估计算法及其特性

在传承经典谱估计和结构化线性系统思想的基础上,介绍了一种基于子空间的超宽带(Ultra-Wide Band,UWB)信道估计(Channel Estimation,CE)快速算法。该算法在低于Nyquist采样率的情况下可获得较高分辨率的信道估计,从而可降低系统的复杂度,减小系统的功耗。     

一种半速率蜂窝移动通信信道指配策略

本文提出了一种新的蜂窝移动通信系统信道指配策略——基于紧凑模式的半速率信道借用指配策略(SRCPCB).这种策略将半速率信道的思想引入到新近提出的CPCB策略中,以短时间降低部分呼叫的话音质量为代价,来降低系统的呼叫阻塞.通过各种业务模型的仿真,获得了系统的初始呼叫阻塞率、强制中断率和话音质量下降率等性能指标.结果表明:SRCPCB的系统综合性能优于FCA、DCA、BCO、BDCL、CPDCA和CPCB等策略.这对于缓解系统频谱资源紧缺、改善系统性能等具有十分重要的意义.     

Dynamic Flow Model for Borrowing Channel Assignment Scheme in Cellular Mobile System

A mathematical model that predicts the dynamic flows in cellular mobile networks that allocate channels using the Borrowing Channel Assignment (BCA) scheme is described in this paper. Two types of handoff procedures – the prioritized and non-prioritized schemes – will be considered in the model. Discrete event simulations were performed and the results were found to be comparable to the results obtained using the mathematical model. Application to comparative study of the dynamic behaviours of the BCA and the Fixed Channel Assignment (FCA) schemes is also presented.     

VCB: An Efficient Resource Sharing Scheme for Cellular Mobile Systems

A new algorithm called Virtual Channel Borrowing (VCB) used to improve the resource sharing performance of a Fixed Channel Assignment (FCA) scheme is proposed and analyzed. The underlying idea is to exploit regions of cell overlap to achieve a balanced distribution of traffic load in non uniform traffic conditions while reducing call blocks and handoff failures. Simulation results show a performance improvement at the expense of additional signaling. Another advantage of VCB is that it can be integrated easily with small additional cost.     

Compact pattern based dynamic channel assignment for cellularmobile systems

A new compact pattern based dynamic channel assignment strategy called CP-based DCA is proposed. The strategy aims at dynamically keeping the cochannel cells of any channel to a compact pattern. A compact pattern of a channel is defined as the pattern with minimum average distance between cochannel cells. CP-based DCA consists of two phases: channel allocation and channel packing. Channel allocation is used to assign an optimal idle channel to a new call. Channel packing is responsible for the restoration of the compact patterns and is performed only when a compact channel is released. Simulation results indicate that the CP-based DCA always performs better than the borrowing with directional channel locking (BDCL) strategy. In the designed example, CP-based DCA is shown to have 2% more traffic-carrying capacity than that of the BDCL in case of uniform traffic, and 8% more traffic-carrying capacity in case of nonuniform traffic, both at a blocking rate of 0.02. Besides, the number of channels reassigned per released call in CP-based DCA is at most one and is, therefore, another advantage over BDCL     

Dynamic Flow Model for Borrowing Channel Ordering Assignment Scheme in Cellular Mobile Systems

A mathematical model that predicts the dynamic flows in cellularmobile networks that allocate channels using the Borrowing ChannelOrdering Assignment (BCO) scheme is described in this paper. Two types ofhandoff procedures – the prioritized and non-prioritized schemes –will be considered in the model. Discrete event simulations wereperformed and the results were found to be comparable to the resultsobtained using the mathematical model. Application to comparative studyof the dynamic behaviours of the BCO, the simple borrowing channel assignment(BCA) and the Fixed Channel Assignment (FCA) schemes is also presented.     

蜂窝移动通信系统中基于紧凑模式的通信借助用指配策略

本文介绍了蜂窝移动通信系统中一种新的动态信道指配策略──基于紧凑模式的信道借用指配策略（ＣＰＣＢ）．这种策略不仅具有基于紧凑模式的动态信道指配的优点,而且具有固定信道指配策略中信道借用的优点．作者将新算法在一种普遍采用的４９个蜂窝的蜂窝通信网络上进行了仿真,分别对几种均匀和非均匀模式的业务分布情况进行了比较,结果表明：ＣＰＣＢ的系统平均阻塞率低于ＦＣＡ、ＢＤＣＬ、基于ＣＰ的ＤＣＡ和ＣＰＭＣＢ等,而且随着负载的增加,其系统平均阻塞率的增长速率也明显低于上述各种策略．     

基于LTE的低空空地信道建模与仿真

低空空地情况下的信道建模是系统分析和设计的基础。在借鉴已有陆地和航空信道建模技术的基础上,分析低空空地信道的特殊性和不同场景下的小尺度衰落参数。针对现有小尺度衰落信道仿真模型的不足,提出了适应低空空地不同场景的小尺度衰落模型。仿真结果表明改进模型更符合理论分析结果。仿真在LTE系统中不同场景下的信道特性,说明区分场景建立低空空地信道模型是必要的。     

一种基于GY／T220．1-2006标准的OFDM信道估计算法

在卫星移动多媒体广播系统中,由于多普勒频移及多径影响,信道是时变的,需要估计出信道的时域或频域响应来消除时变信道对传输信号的影响。针对GY/T 220.1-2006标准的导频插入图案,提出了一种基于LS估计准则、在时间轴方向二维线性内插、频域轴方向变换域内插的信道估计算法。仿真结果表明,在不同多径信道的情况下,随着信噪比的增加,该算法的性能均优于最近插值、线性插值和低通滤波插值算法。该算法计算复杂度较spline插值和cubic插值低,适于硬件实现。     

Distributed spectrum assignment for cognitive networks with heterogeneous spectrum opportunities

This paper presents a distributed and localized interference‐aware channel assignment framework for multi‐radio wireless mesh networks in a cognitive network environment. The availability of multiple interfaces and channels in wireless devices is expected to enhance network throughput in wireless mesh networks. A notable design issue in such networks is how to dynamically assign available channels to multiple radio interfaces for maximizing effective network throughput by minimizing interference. The proposed framework uses a novel interference estimation method by utilizing distributed conflict graphs on a per‐interface basis. Presented results obtained via simulation studies in 802.11 based multi‐radio mesh networks indicate that for both homogeneous and heterogeneous primary networks, the proposed protocol can facilitate a large increase in network throughput in comparison with a Common Channel Assignment mechanism that is used as a benchmark in the literature. Copyright © 2010 John Wiley & Sons, Ltd.     

A Channel Sharing Scheme for Cellular Mobile Communications

This paper presents a channel sharing scheme, Neighbor Cell Channel Sharing (NCCS) , based on region partitioning of cell coverage for wireless cellular networks. Each cell is divided into an inner-cell region and an outer-cell region. Cochannel interference is suppressed by limiting the usage of sharing channels in the inner-cell region. The channel sharing scheme achieves a traffic-adaptive channel assignment and does not require any channel locking. Performance analysis shows that using the NCCS scheme leads to a lower call blocking probability and a better channel utilization as compared with other previously proposed channel assignment schemes.