计弱连接条件下网络数据多信道传输节点路径调控方法

针对传统方法在计弱连接条件下调控网络数据传输路径时,无法均匀调整传输节点路径上的信息量,导致数据传输能耗较大且数据传输效率低,提出一种计弱连接条件下网络数据多信道传输节点路径调控方法。构建网络数据多信道传输节点模型,确定最佳的数据传输节点路径队列,使传输节点路径上的信息量均匀传输。利用信道分配的路径调控方法进行数据传输节点路径优化,有效降低数据传输能耗,提高了数据多信道节点传输效率,完成对计弱连接条件下网络数据多信道传输节点路径的调控。实验结果表明,该方法有效提高了数据多信道节点传输的效率,可有效解决传统方法存在的弊端,对该领域发展有着重要意义。     

认知无线电网络基于D-OFDM的中继选择算法

认知无线电技术能有效提高频谱利用率,而协作中继是解决信号在无线媒介中消失问题的关键技术。文章基于认知无线电网络,通过创建协作表,提出了一种利用协作中继提高频谱利用率和数据传输速率的中继选择算法。其中的协作表包括信道增益、信道可用率和认知节点的不同频谱。该算法通过选择合适的中继节点以最大化源节点的传输速率。仿真结果表明了该中继选择算法的有效性。     

一种基于机会中继的多跳协作MAC机制

现有协作MAC机制的实现过度依赖于协作表中的信息,而协作表中的信息并不是瞬时更新的,并且协作表的建立和更新都需要额外的开销。针对这些不足,充分利用协作发送的特性,提出一种基于机会中继的多跳协作MAC机制。在ORMAC机制中,节点通过侦听MCTS估算中继信道的误包率,当数据传输失败后,候选中继节点根据误包率设置退避定时器的初值,以选择出最佳的中继节点参与中继重传,以此在不可靠的无线信道实现数据的可靠传输。在NS2.28上搭建仿真平台,仿真结果证实了ORMAC机制能有效地提高系统中的平均吞吐量和交付率。     

基于无线传感器网络汇聚传输实时性的分布式调度算法

在无线传感器网络多种应用中,各节点需要在短时间内将采集的数据传输至汇聚节点,从而形成多对一的汇聚传输。针对网络汇聚传输的实时性,提出了一种分布式的节点传输调度算法。各节点只需要根据一跳范围内的邻居信息进行传输调度。仿真和分析表明该算法可以有效避免数据碰撞,并使得完成一次全网数据收集所需要的时隙数基本在网络节点总数的1.6到1.8倍左右,比目前其他调度算法在实时性和复杂度方面更具有优势。     

基于稀疏密集阵传输机制的WSN数据传输汇聚算法

为了改善无线传感网(WSN)的数据传输汇聚能力,提出了基于稀疏密集阵传输机制的WSN数据传输汇聚算法。引入核生成函数,设计了一种新的传输矩阵,将簇头节点与sink节点之间连通程度及负载程度进行量化,以提升簇头节点传输效果的评估能力;采用特征向量按列排序并结合卷积算法降低簇头节点传输值,以有效减少簇头节点负载;采用树分解模式搜寻可用哈密尔顿回路,构建了基于路径分解优化机制的汇聚稳定方法;通过使用哈密尔顿寻址来优化叶子节点与根节点之间的数据链路,以增强簇头节点覆盖能力与提高数据传输过程的稳定性能。仿真实验表明,与当前常用的基于阈值筛选模糊分簇的WSN数据稳定汇聚算法和面向医疗应用的无线传感器网络多径数据传输方法相比,所提算法具有更为集中的传输报文集中度,以及更高的传输链路抖动控制能力和网络汇聚带宽。     

基于D2D通信系统中的一种跨层中继选择算法

在D2D通信系统与蜂窝网络共存的场景下,引入中继节点可有效提高D2D链路的吞吐量和D2D用户对蜂窝用户的干扰。文中基于译码转发模式,结合跨层协作通信的思想,提出了一种基于物理层和数据链路层的跨层中继选择算法。该算法结合物理层的信道状态信息和数据链路层的队列状态信息,两个参数进行最优中继节点的选择。并最终通过仿真验证表明,基于跨层中继选择算法可提高通信系统的吞吐量,同时降低了通信系统的平均时延和数据包错误率。     

多接口多信道无线网状网的信道动态切换研究

首先介绍了目前常见的信道动态切换方法,并分别分析了他们的优缺点.然后针对他们的通信节点之间需要同步而难以实现或各个节点需要一个公共控制信道来解决数据信道的争用而影响网络吞吐率等缺点,提出了一种基于信道队列的信道动态切换方法.该方法不需同步机制和公共控制信道,每个接口通过信道队列的队头元素产生下次新的切换信道,较好的确保了各信道传输的公平性;QDSAC能使网络中各节点的信道切换序列独立生成,计算代价也小,较好的保证了信道切换序列生成的实时性,从而提高网络吞吐率.     

协作OFDM系统中的子载波选择算法

研究了协作正交频分复用系统的中继方案,提出了OFDM协作分集系统中的子载波选择算法,根据子信道信息,在容量准则下,选择可以提高系统容量的子载波,以放大前传的方式转发源节点信息。仿真结果表明,在中继节点功率与源节点功率较低或中继节点靠近源或目的节点时,所有子载波都采用中继传输可降低系统容量;子载波选择算法可以改善系统容量,并且选择合适的中继节点发射功率和中继位置,可以显著提高系统容量,当中继节点位于源与目的节点中点时,系统容量最大。     

非对称双向中继系统中的协作多址广播传输方案设计与数据率性能分析

在双向中继系统中,2个节点通过一个半双工中继交换信息,2个方向的数据率都会受到较差链路的制约。当节点位置变化或信道衰落造成,中继两端的信道质量不对称时,这将导致系统的和数据率下降。为了弥补较差链路带来的数据率损失,提出了一种新的三时隙协作多址广播传输方案,使得信道质量较好的源节点与中继节点进行协作传输,并且各节点充分利用各链路所支持的最大数据率进行传输,从而有效提高系统容量及加权和数据率。推导出新方案的容量上界以及解码转发模式下的可达数据率域,并对时隙及功率等资源进行优化分配。仿真结果表明,在加性白高斯和瑞利衰落信道下,新方案在非对称信道下的性能都大大优于已有方案。     

利用智能天线实现多点中继功能的Ad Hoc网络MAC协议

在Ad Hoc网络中,采用多跳传输来提高数据传输的质量以及速率。传统的单中继节点已经不能适应迅速增大的数据量以及节点的移动造成的信道衰落情况,所以本文提出了基于智能天线实现多点中继的MAC协议,该协议采用了智能天线实现了菱形握手机制,使数据实现同步传输。其次采用空时编码的协作机制,通过估计源信号来防止中继节点与目的节点信道衰落的情况。最后利用Busy Tones解决了隐藏终端和暴露终端的问题。通过仿真与比较证明MRDMAC协议在数据延时和通过率等各个方面都有很大的优越性。     

Distributed congestion control strategy using network utility maximization theory in VANET

Cooperative vehicle safety system (CVSS) rely on periodical beacons to track neighboring vehicles.High traffic density often causes channel congestion,seriously damaging the performance of CVSS.Existing congestion control strategies aim to ensure the performance in network layer,without considering the service requirements of vehicles in different driving contexts.To solve the problem,a distributed congestion control strategy using network utility maximization (NUM) theory was proposed.First of all,the NUM model for channel resource allocation was introduced.A utility function reflecting vehicle’s safety requirements was proposed in the model.Then under the condition of fixed transmit powers,a optimization problem of channel resource allocation was proposed.Lastly,to solve the optimization problem,a distributed congestion control algorithm named utility-based rate congestion control (UBRCC) algorithm was designed,the algorithm worked out the optimal beaconing rate by updating vehicle’s congestion price,realizing the resource allocation according to vehicle’s safety requirements.Simulation results validate that UBRCC algorithm can efficiently control channel congestion,reduce transmission delay,ensure reliable data transmission and satisfies the requirements of safety applications.     

基于事件驱动的动态分簇网络的协作传输方法

针对事件驱动的无线传感器网络的传输可靠性问题,该文利用节点间的互助,提出一种基于事件驱动的动态分簇网络的协作传输方法。无事件发生时,各节点按预先形成的静态簇低频传输数据。而一旦有事件发生,能感知事件发生的节点快速组成事件簇,向簇头发送采集的数据,簇头融合数据后发往汇聚节点。为提升传输可靠性,当簇头传输失败时,由最佳中继协作转发数据给汇聚节点。在最佳中继的选择上,考虑到事件的连续移动,以及处于事件前向通道上的节点具有较大的感应值和较好的协作能力等条件,该文提出了基于前向通道的最佳中继选择策略。仿真和实验结果表明,所提协作传输方法能够有效提高传输可靠性。     

非对称速率的双向中继信道物理层网络编码

本文提出了基于非对称速率的双向中继信道的物理层网络编码方案。本文所提方案联系实际无线通信信道的差异性,不但考虑了较差链路的最大传输性能以保证其传输的可靠性,而且在较优链路采取较高速率进行传输,从而充分利用较优链路来传输更多信息,增加通信系统的信道容量。为实现不对称速率传输,其基本思想是在较差链路中加入已知信息,通过已知信息可减小中继节点接收到的叠加信号的星座图,使得通信系统的译码性能得到提升。在中继节点,根据叠加信号的星座图对叠加信号进行联合解调,在节省了系统工作时隙的同时也减小了系统的复杂度。仿真结果表明了采用非对称速率传输不但可保证信息传输的可靠性,还可提高通信系统的信道容量,充分利用系统资源。      

A scalable joint routing and scheduling scheme for large-scale wireless sensor networks

The multihop configuration of a large-scale wireless sensor network enables multiple simultaneous transmissions without interference within the network. Existing time division multiple access (TDMA) scheduling schemes exploit gain based on the assumption that the path is optimally determined by a routing protocol. In contrast, our scheme jointly considers routing and scheduling and introduces several new concepts. We model a large-scale wireless sensor network as a tiered graph relative to its distance from the sink, and introduce the notion of relay graph and relay factor to direct the next-hop candidates toward the sink fairly and efficiently. The sink develops a transmission and reception schedule for the sensor nodes based on the tiered graph search for a set of nodes that can simultaneously transmit and receive. The resulting schedule eventually allows data from each sensor node to be delivered to the sink. We analyze our scheduling algorithm both numerically and by simulation, and we discuss the impact of protocol parameters. Further, we prove that our scheme is scalable to the number of nodes, from the perspectives of mean channel capacity and maximum number of concurrent transmission nodes. Compared with the existing TDMA scheduling schemes, our scheme shows better performance in network throughput, path length, end-to-end delay, and fairness index.     

Energy‐Aware Hybrid Cooperative Relaying with Asymmetric Traffic

In this paper, we study an asymmetric two‐way relaying network where two source nodes intend to exchange information with the help of multiple relay nodes. A hybrid time‐division broadcast relaying scheme with joint relay selection (RS) and power allocation (PA) is proposed to realize energy‐efficient transmission. Our scheme is based on the asymmetric level of the two source nodes’ target signal‐to‐noise ratio indexes to minimize the total power consumed by the relay nodes. An optimization model with joint RS and PA is studied here to guarantee hybrid relaying transmissions. Next, with the aid of our proposed intelligent optimization algorithm, which combines a genetic algorithm and a simulated annealing algorithm, the formulated optimization model can be effectively solved. Theoretical analyses and numerical results verify that our proposed hybrid relaying scheme can substantially reduce the total power consumption of relays under a traffic asymmetric scenario; meanwhile, the proposed intelligent optimization algorithm can eventually converge to a better solution.     

交通路灯监控系统的无线传感网链状路由算法

在交通路灯监控系统中为节省网络节点能耗和降低数据传输时延,提出一种无线传感网链状路由算法（CRASMS）。该算法根据节点和监控区域的信息将监控区域分成若干个簇区域,在每一个簇区域中依次循环选择某个节点为簇头节点,通过簇头节点和传感节点的通信建立簇内星型网络,最终簇头节点接收传感节点数据,采用数据融合算法降低数据冗余,通过簇头节点间的多跳路由将数据传输到Sink节点并将用户端的指令传输到被控节点。仿真结果表明：CRASMS算法保持了PEGASIS算法在节点能耗方面和LEACH算法在传输时延方面的优点,克服了PEGASIS 算法在传输时延方面和LEACH算法在节点能耗方面的不足,将网络平均节点能耗和平均数据传输时延保持在较低水平。在一定的条件下,CRASMS算法比LEACH和PEGASIS算法更优。     

Resource allocations in relay‐assisted cellular networks

In a relay‐assisted cellular network, the transmission mode (either direct transmission or relaying) and the transmit power of the source and relay nodes affect not only transmission rates of individual links but also the rates of other links sharing the same channel. In this paper, we propose a cross‐layer design that jointly considers the transmission mode/relay node selection (MRS) with power allocation (PA) to optimize the system rate. We first formulate an optimization problem for a cellular system, where the same frequency channel can be reused in different cells. A low complexity heuristic MRS scheme is proposed on the basis of the link and interference conditions of the source and potential relay nodes. Given the transmission mode and relay node (if the relaying mode is chosen) of each link, the transmit power of the source and relay nodes can be solved by geometric programming. This method for MRS and PA can achieve a close‐to‐optimum performance, but implementing the PA requires heavy signalling exchanged among cells. To reduce the signalling overheads, we finally proposed a heuristic and distributed method for MRS and PA inspired by some asymptotic analysis. Numerical results are conducted to demonstrate the rate performance of the proposed methods.Copyright © 2013 John Wiley & Sons, Ltd.     

Residual energy based multi-relay selection and power allocation scheme in two-way relay network

In this paper, we have proposed a multi-relay selection and power allocation scheme for two-way relay network which aims to maximize the sum-rate of two-way relay system. First, to prolong network lifetime, a multi-relay selection strategy is proposed in which both channel state information （CSI） and remaining energy （RE） are considered. Next, a multi-relay power allocation algorithm based on convex optimization （MRPA-CO） is presented. To reduce the computational complexity, it can be divided into two steps： terminal nodes power allocation （TNPA） and relay nodes power allocation （RNPA）. Simulation results indicate that the proposed relay selection strategy can significantly prolong network lifetime compared to other relay selection strategies which consider CSI only, and the MRPA-CO algorithm has great advantage over equal power allocation （EPA） on sum-rate in two-way relay network.     

一种快速低开销的移动节点分布式寻路RPL路由协议

针对低功耗有损网络(Low Power and Lossy Network, LLN)中移动节点作为中继节点时,存在无线链路易断开、数据传输成功率较低和控制开销较高的问题,提出了一种快速低开销的移动节点分布式寻路RPL路由协议(Mobile Node Distributed Pathfinding RPL Routing Protocol, MNA-RPL)。首先,提出一种邻居表自适应更新机制,依据邻居表快速切换父节点;其次,提出一种父子节点双断开机制,能够有效减少数据包丢失;最后,提出一种基于速度动态管理的Trickle计时器,根据自身速度动态调整DIO广播周期。理论分析和仿真结果表明,与主流路由协议相比,该协议在数据传输和控制开销等方面的性能均有一定的提升。