协同信号驱动和区域健壮性感知的机会可靠传输机制

针对无线传感器网络中区域通信特性和信号驱动问题,研究了一种能够提供高效可靠数据通信的基于协同信号驱动和区域健壮性感知的机会可靠传输机制.首先基于信号冗余度、并行通信和信号融合,建立了多路径传输协同信号驱动模型;基于区域划分建立子网序列状态矩阵,构建区域健壮性感知模型;提出了一种适用于无线传感器网络的高效可靠的机会可靠传输机制.数学分析与实验结果表明:所提出的传输机制在实时性、稳定性、可靠性、信号识别等方面具有优秀表现.     

基于服务质量机会测量的传感器网络协作控制机制*

为了消除制约无线传感器网络性能的因素和提高网络控制效率,基于实时网络服务质量机会测量,提出了传感器网络协作控制机制。首先,基于发送端节点和接收端节点状态以及中继节点的协作,测定无线传感器网络实时状态。其次,分析能耗品质和负载品质对网络性能的影响规律。接着,讨论不同分频调制方式对网络性能的影响规律。最后,制定了网络状态感知的机会分频调制的传感器网络协作控制机制。数学分析和实验结果表明,所提出的传感器网络协作控制机制对无线传感器网络的实时性、可靠性和吞吐率等方面具有较强的保障能力。     

无线传感器网络基于通信距离的协作ARQ策略

提出了一种适用于无线传感器网络的基于通信距离的多中继协作ARQ策略,从而为无线数据传输提供了可靠性,同时获得了较高的吞吐率和能量效率.首先根据ARQ机制和在链路层将数据包分割为若干个数据帧的规律,建立一种马尔科夫链模型;在此基础上,分析饱和吞吐率、数据包丢弃概率、平均时延和能效的性能随通信距离的变化规律;最后提出了基于通信距离的协作ARQ策略.针对线性无线传感器网络,分析比较了所提协作ARQ与传统ARQ的通信性能.数学分析结果表明,所提协作ARQ能获得比传统ARQ更优的饱和吞吐率、可靠性和能效.     

基于传输误差的网络控制系统调度方法

提出一种基于网络传输误差的控制系统调度方法,分析经典的静态和动态调度策略,给出通信网络的可调度性判据和网络调度下的控制性能稳定性约束。针对不可调度情况,使用网络监测得到网络传输误差,调整传感器的采样周期和在控制器进行数据包补偿的方法,并通过仿真实验验证该方法的有效性。     

无线传感器网络节点定位误差的估算方法

针对无线传感器网络节点定位时非直线传播误差的影响,提出一种基于信号单径到达时间和接收能量比的NLOS(Non-line of sight)估计算法。本算法以单径到达时间为基础,结合接收能量衰减状况,建立了基于信号传播路径损耗模型的NLOS估算式,并结合天线系统方向性的影响对估计结果进行必要的修正。实测数据表明:经NLOS校正后节点定位误差能控制在45 cm以内,可满足各种无线传感器网络的节点定位需要。     

一种改进的室内wsn仿真模型

针对室内无线传播模型具有多径传播效应的特性和无线传感器网络协议栈的特点,提出了一种改进的室内无线传感器网络仿真方法。方法使用阴影模型模拟室内无线传播模型的多径传播效应,结合常用的无线传感器网络节点芯片的性能参数预测出无线信号在室内的实际传输距离,并在NS2中以该无线信道模型为基础,以无线传感器网络协议栈为标准,建立了一个改进的室内无线传感器网络仿真模型。仿真模型的测试结果表明该模型在数据包投递率及网络剩余能量的比率上与实际室内无线传感器网络的性能相似。证明建立的模型能为室内无线传感器网络的实际布网和应用提供可靠的依据。     

无线传感器网络通信性能确定上界研究

无线传感器网络一般具有实时性,其端到端通信性能上界研究具有重要意义.基于确定性网络演算理论,对无线传感器网络为保证实时数据优先的数据转发调度策略进行了性能分析与评价.建立了基于确定性网络演算的端到端通信性能分析模型,经过理论分析得到了无线传感器网络节点的数据队列上界、端到端数据流的延迟上界以及端到端数据流的延迟抖动上界.仿真结果表明基于网络演算理论的无线传感器网络性能上界均在理论计算的上界范围之内.本文的研究使得对无线传感器网络通信性能的研究更符合完备性的要求.     

基于GOP取帧和跳数的自适应协作ARQ

为给多媒体数据传输提供有效QoS保障,提出一种适用于无线多媒体传感器网络数据传输的自适应协作ARQ机制。采用跨层设计的方法,分析ARQ机制协作传输跳数与能效的规律,根据节点间通信距离自适应选取最优协作传输跳数,结合数据帧跳数,自适应调整最大重传次数,根据快进快退码率基于帧间依赖关系进行GOP取帧。分析结果表明,该机制在丢包率和端到端平均时延方面与传统ARQ相比具有较优的性能,能有效提高无线多媒体传感器网络通信的可靠性和实时性。     

一种改进的瑞利小波算法无线传感器网络流媒体传输研究

针对无线传感器网络中带宽和能量受限、误码率高、信道不稳定等因素严重影响了实时流媒体传输的问题,采用瑞利小波模型模拟无线传感器网络流媒体通信,并给出概率分布和突发特性的分析模型,基于Kal-man滤波器实时预测网络带宽,自适应地在SCTP与PRSCTP之间进行切换。仿真实验表明,瑞利小波模型能够准确地描述实时流媒体通信流,Kalman滤波器可以准确地预测实时网络带宽,而且基于带宽预测的流媒体传输技术与原有的技术相比在分组成功投递率、端到端时延和吞吐率上均具有良好的性能。     

无线网络链路质量感知的机会网络编码机制

现有的无线网络编码机制大多没有考虑无线链路质量对于通信性能的影响,导致网络吞吐量降低。针对这一问题,提出一种链路质量感知的机会网络编码机制(LONC)。该机制充分利用无线媒介的共享特性,将网络编码和机会转发技术相结合,通过期望传输次数来计算数据包传输效用值,用于衡量数据包传输效率。在此基础上,根据效用值动态分配数据包调度优先级,使得高优先级的数据包有更高的概率获得转发机会,从而有利于提高网络吞吐量。仿真结果表明,LONC机制能够显著提高网络的吞吐量,在一定程度上保证了数据的可靠传输。     

无线传感器网络跳数和通信距离自适应差错控制策略

无线传感器网络(WSNS)的动态信道特性、网络带宽和节点能量受限等特点,使得在无线环境下为数据传输提供可靠性保证面临更大的挑战.本文提出一种适用于WSNS的自适应链路层差错控制策略(AEC-Hops/RSSI),以便改善WSNS的通信性能.首先建立数学模型,分析数据帧被转发所经历的跳数与能效的变化规律,然后分析前向纠错...     

A new efficient error control algorithm for wireless sensor networks in smart grid

Error detection and correction is an important issue in the design and maintenance of a smart grid communication network to provide reliable communication between sender and receiver. Various error-control coding techniques are employed to reduce bit error rates (BER) in wireless sensor networks (WSNs). The performance of these techniques is also compared and evaluated to find the most suitable technique for WSNs. This is the first study to compare the most efficient coding techniques in the smart grid environment, and it suggests a new error correction algorithm based on this comparison result. Therefore, this article first examines and compares two forward error control (FEC) coding techniques such as Bose-Chaudhuri-Hochquenghem code (BCH) and Reed Solomon code (RS) with various modulation methods including frequency shift keying (FSK), offset quadrature phase-shift keying (OQPSK), and differential phase shift keying (DPSK) in a 500 kV line-of-sight (LoS) substation smart grid environment. Second, as a result of this comparison, a new adaptive error control (AEC) algorithm is proposed. Adaptive error control adaptively changes error correction code (ECC) based on the channel behavior that is observed through the packet error rate (PER) in the recent previous transmissions. The link-quality-aware capacitated minimum hop spanning tree (LQ-CMST) algorithm and the multi-channel scheduling algorithm are used for data transmission over the log-normal channel. Therefore, the performance of compared coding techniques and AEC are also evaluated when multiple channels are used during transmission. Further, AEC is compared with static RS and without-FEC methods based on performance metrics such as the throughput, BER, and delay in different smart grid environments, e.g., 500 kV Substation (LoS), underground network transformer vaults (UTV) (LoS), and main power control room (MPR) (LoS). Our simulation results indicate that the proposed AEC algorithm achieves better performances than all those techniques.     

Try-once-discard scheduling for stochastic networked control systems

In practical networked control systems (NCS), such as smart grids, cooperative robotics, and sensor networks, often multiple control applications share a communication infrastructure, requiring a smart and efficient scheduling mechanism to coordinate the access to the capacity-limited communication medium. In this article we consider the problem of event-based scheduling design for NCSs consisting of multiple control loops over a shared communication medium. We extend the notion of Try-Once-Discard (TOD), which is one of the basic deterministic event-based scheduling protocols for resource constrained NCSs, to the case of multiple stochastic control systems coupled via a shared communication medium subject to capacity limitation and stochastic packet delivery failure. Showing that the overall network-induced error is a homogeneous Markov chain in our stochastic set-up, we first study stability properties of such networked systems under the TOD scheduling scheme employing the concepts of stochastic stability. Then, we derive sufficient stability conditions under the TOD rule assuming that the communication channel is not ideal, i.e. a scheduled data packet for transmission might be lost in the communication channel with a non-zero probability. Furthermore, we derive analytic performance bounds by finding uniform upper-bounds for an average quadratic cost function. The numerical simulations are performed for variety of system parameters and NCS set-ups to strengthen our stability claim as well as illustrating performance bounds. Additionally, we show that the TOD scheduling rule outperforms the conventional time-triggered, and uniform and non-uniform random channel access arbitration mechanisms, in terms of efficient coordination of channel access in stochastic NCSs.     

Packet loss resilience using unequal forward error correction assignment for video transmission over communication networks

Forward error correction (FEC) methods have been developed for packet loss resilience in application layer for real-time video transmission over communication networks. In this paper, an efficient packet loss resilience method is proposed using closed form solution for unequal FEC assignment based on a new packet distortion model. We first derive the packet distortion model by investigating the error concealment property and error propagation effect in H.264. To select the source and channel rate minimizing the overall distortion, we present a model-based rate allocation algorithm using the packet distortion model and rate-distortion function. Then we propose the closed form solution for unequal FEC assignment, which uses the packet distortion model and considers channel status information. Simulation results show that the proposed method gives substantial improvement for the received video quality in packet-lossy Internet and wireless network environments, while it requires much less computational complexity compared to the previous scheme.     

基于LT喷泉码的WSNs抗WLAN干扰的实验研究

针对无线传感器网络(WSNs)通信能力有限,易受到与其共享信道的无线局域网(WiFi)干扰的问题,提出一种采用纠删码——LT喷泉码编码来保证可靠传输的方法。该方法可以充分利用喷泉码的无码率特性,即发送端源源不断地发送经过LT码编码的编码包,接收端只要接收到足够数量的编码包,就能够成功恢复原始数据包。在CC2430为核心的平台上设计并实现了基于LT喷泉码的可靠传输协议,并在WLAN干扰情况下对其进行了性能测试。实验结果表明:基于LT喷泉码的可靠传输协议对WLAN的抗干扰效果显著。     

Optimal replicator factor control in wireless sensor networks

For TDMA MAC protocols in wireless sensor networks (WSNs), redundancy and retransmission are two important methods to provide high end-to-end transmission reliability. Since reliable transmissions will lead to more energy consumption, there exists an intrinsic tradeoff between transmission reliability and energy efficiency. For each link, we name the number of its reserved time slots in each MAC superframe as a replicator factor. In the following paper, we propose a reliability-lifetime tradeoff framework (RLTF) for WSNs to study replicator factor control problem. First, for the redundancy TDMA MAC, we formulate replicator factor control problem as convex programming. By the gradient projection method, we develop a fully distributed algorithm to solve the convex programming. Second, for the retransmission TDMA MAC, we set the retransmission upper bound for each link according to the optimal replicator factors under the redundancy MAC and compute the total communication overhead for the retransmission MAC. Finally, we compare the communication overhead of these two MAC protocols under different channel conditions.     

基于混合纠错技术的北斗长报文可靠传输机制设计

北斗卫星导航系统的短报文通信功能在传输容量上具有一定的限制,并且无回执信息,属于不可靠的通信方式。为了提高长数据报文的传输可靠性,通过对传输协议的改进,提出了一套基于混合纠错技术的长报文可靠传输机制。通过前向纠错技术和自动重传请求技术的结合,能够对一定范围内的出错情况进行自纠正,并对超出自纠能力的传输出错进行反馈重传,从而提高传输的可靠性。     

一种优化时延的机会协同组播调度策略

无线组播面临的最大问题是各个用户信道状态的不均匀性和波动性,无法同时满足所有用户的服务质量需求。无线蜂窝通信系统中,为实现可靠组播,数据包不可避免地需要被重传多次,组播的时延也因此增加。本文我们首先分析了协同组播调度CMS策略的时延,并且推导了基于信道信息全知条件下的最小时延。另外,我们在部分信道信息未知条件下提出了一种机会协同组播策略来优化组播时延。仿真数据显示,我们提出的机会协同组播调度OCMS策略在时延性能上几乎达到了我们所分析的CMS策略的最小值而且明显优于其他调度策略。     

A Class of Cross‐Layer Optimization Design for Congestion and Energy Efficiency with Compressed Sensing in Wireless Sensing Networks

In wireless sensor networks (WSNs), the congestion problem not only causes packet loss, but also leads to an increase in delays and energy consumption. The actual performance of wireless sensor networks (WSNs) can be severely influenced by the quality of the communication channel and the bit in transmission. In this paper, the distributed protocols, which attain global optimum control for signals by the compressed sensing technique and achieve fair channel allocation by the scheduling algorithm, are proposed for WSNs. We take into account the congestion problem by robust optimization with congestion ratio for two classic aspects in energy limited WSNs: minimum transmission rate and maximum transmitted information. To achieve the goal, three protocols are developed. In the first protocol, the desired control input is designed based on the compressed sensing technique. A minimal bit of signal is provided to reduce the transmission flow for the congestion model. The second protocol is resource allocation. The resources can be allocated increasingly to the channel in order to avoid more severe congestion. This can also avoid conservative reduction of resource allocation for eliminating congestion. Channel selection abides by the fair resource allocation principle. The above protocols separately are implemented through a congestion ratio at network layer, transport layer, and MAC layer. Simulation results demonstrate that the proposed algorithm effectively relieves congestion, and achieves higher throughput and lower energy consumption.     

基于探测的多信道无线网状网机会路由算法

多信道无线网状网的性能在很大程度上依赖于信道分配和路由选择.现有的多信道无线网状网路由大多没有考虑信道之间的干扰问题,从而导致通信性能下降.针对这一问题,提出一种基于探测的多信道无线网状网机会路由(POR)算法.首先,根据干扰能量,选出最佳通信信道集来降低信道间的传榆干扰.在此基础上,采用探测方式计算路径期望传输时延,确定候选链路集并运用机会路由机制进行数据传输以最小化端到端的传输时延.实验结果表明,POR可以显著地降低平均端到端时延,提高数据包投递率,为数据传输提供实时性和可靠性保证.