Maximum Network Throughput Based on Cross-Technology Communication for Sensor Networks

The exponentially increasing number of heterogeneous Internet of Things(Io T)devices(e.g.,Wi Fi and Zig Bee)crowed in the same ISM band(2.4 G)and recent advances in CrossTechnology Communications(CTC)motivate us to explore more efficient data collection and maximize network throughput.CTC enables Wi Fi and Zig Bee devices to communicate directly without any hardware changes or gateway equipment,which sheds light on a more efficient data collection design.In this work,we propose a distributed algorithm,named Max Bee,to compute the maximum network throughput,which is formulated as a linear programming problem.Considering that the problem turns out to be non-convex and hard to solve exactly,we propose a distributed algorithm to solve nonlinear programming by using the dual decomposition method and gradient/subgradient algorithms.Through extensive simulations on different sets of deployed Zig Bee and Wi Fi devices,we observe that the proposed algorithm significantly increases the network throughput based on CTC for Sensor Networks.

Resource-constrained maximum network throughput on space networks

This paper investigates the maximum network through- put for resource-constrained space networks based on the delay and disruption-tolerant networking （DTN） architecture. Specifically, this paper proposes a methodology for calculating the maximum network throughput of multiple transmission tasks under storage and delay constraints over a space network. A mixed-integer linear programming （MILP） is formulated to solve this problem. Simula- tions results show that the proposed methodology can successfully calculate the optimal throughput of a space network under storage and delay constraints, as well as a clear, monotonic relationship between end-to-end delay and the maximum network throughput under storage constraints. At the same time, the optimization re- sults shine light on the routing and transport protocol design in space communication, which can be used to obtain the optimal network throughput.

Stochastic Geometric Analysis of the Uplink Throughput in Cognitive Radio Cellular Networks

This paper investigates the uplink throughput of Cognitive Radio Cellular Networks(CRCNs).As oppose to traditional performance evaluation schemes which mainly adopt complex system level simulations,we use the theoretical framework of stochastic geometry to provide a tractable and accurate analysis of the uplink throughput in the CRCN.By modelling the positions of User Equipments(UEs)and Base Stations(BSs)as Poisson Point Processes(PPPs),we analyse and derive expressions for the link rate and the cell throughput in the Primary(PR)and Secondary(SR)networks.The expressions show that the throughput of the CRCN is mainly affected by the density ratios between the UEs and the BSs in both the PR and SR networks.Besides,a comparative analysis of the link rate between random and regular BS deployments is concluded,and the results confirm the accuracy of our analysis.Furthermore,we define the cognitive throughput gain and derive an expression which is dominated by the traffic load in the PR network.

THROUGHPUT ANALYSIS OF TWO-HOP WIRELESS NETWORKS WITH NETWORK CODING

A Two-hop Wireless Network (TWN) is the basic topology structure that provides network coding opportunity for improving throughput. Network coding on a homogeneous TWN, in which all the data flows have the same packet size and all the links have the same transmission rate, has been extensively investigated. In this paper, network coding on more practical heterogeneous TWNs, featured by various packet sizes and transmission rates, is studied. Based on the Markov model, the throughput of the proposed network coding scheme, together with the throughput gain, is derived, which matches the simulation results very well. Numerical analyses indicate that, encoding the packets with close size and close transmission rate and enlarging buffer size at the relay node help in improving the throughput gain.

Improving Queuing System Throughput Using Distributed Mean Value Analysis to Control Network Congestion

In this paper, we have used the distributed mean value analysis (DMVA) technique with the help of random observe property (ROP) and palm probabilities to improve the network queuing system throughput. In such networks, where finding the complete communication path from source to destination, especially when these nodes are not in the same region while sending data between two nodes. So, an algorithm is developed for single and multi-server centers which give more interesting and successful results. The network is designed by a closed queuing network model and we will use mean value analysis to determine the network throughput (b) for its different values. For certain chosen values of parameters involved in this model, we found that the maximum network throughput for β≥0.7?remains consistent in a single server case, while in multi-server case for β≥ 0.5?throughput surpass the Marko chain queuing system.

Increasing Throughput and Reducing Delay in Wireless Sensor Networks Using Interference Alignment

With the advent of sensor nodes with higher communication and sensing capabilities, the challenge arises in forming a data gathering network to maximize the network capacity. The channel sharing for higher data transmission leads to interfering problems. The effects of interferences become increasingly important when simultaneous transmissions are done in order to increase wireless network capacity. In such cases, achieving a high throughput and low delay is difficult. We propose a new method that uses interference alignment (IA) technique to mitigate interference effects in Wireless Sensor Networks (WSNs). In IA technique, multiple transmitters jointly encode their signals to intended receivers such that interfering signals are separated and eliminated. Simulation results demonstrate that compared to TDMA algorithms, the proposed method significantly increases the performance of the network delay and throughput by reducing the delay and increasing throughput.

Throughput Estimation with Noise Uncertainty for Cyclostationary Feature Detector in Cognitive Radio Network

Cognitive Radio Networks (CRNs) are recognized as the enabling technology for improving the future bandwidth utilization. In CRNs secondary users are allowed to utilize the frequency bands of primary users when these bands are not currently being used. The secondary users are required to sense the radio frequency environment. The lower the probability of false alarm, the more chances the channel can be reused and the higher the achievable throughput for the secondary network. The main contribution of this paper is to formulate the sensing-throughput-noise uncertainty tradeoff for cyclostationary feature detection. Computer simulations have shown that for a 1 MHz channel, when the sensing duration is 2% of total time, the spectrum will get 99% probability of detection regardless of 50% noise uncertainty.

网络拥塞控制方法综述

网络拥塞控制方法是决定网络传输性能的关键因素.近几年,网络不断普及、网络带宽不断增长、用户对网络性能的需求不断提升,为拥塞控制算法的设计带来挑战.为适应不同的网络环境,近期不少新颖的拥塞控制算法被研究者们提出来,极大地提升网络的传输性能,改善用户体验.综述最新拥塞控制算法设计思想,将其分为预约调度式、直接测量式、基于机器学习式以及迭代探测式4大类,分别介绍相应的代表性拥塞控制算法,并进一步对各种拥塞控制思想方法的优缺点进行对比和分析,最后展望拥塞控制的未来发展方向,以启发该领域的研究.

基于SWIPT的能量收集WSN吞吐量性能分析及优化

针对能量收集无线传感器网络(wireless sensor network,WSN)中的两跳多中继传输问题,构建无线射频能量站(power beacon,PB)辅助的能量收集无线携能通信(simultaneous wireless information and power transfer,SWIPT)中继模型.在中继节点具有捕获源节点、环路自干扰和PB信号能量的特性下,推导目的节点采用选择式合并(selection combining,SC)、最大比合并(maximal ratio combining,MRC) 2种不同接收策略下的中断概率和吞吐量,继而在保障通信服务质量(quality of service,QoS)、PB发射功率、能量转化效率等多约束条件下,提出一种以吞吐量最大化为目标的联合优化时隙切换因子与功率分配因子的中继选择算法.仿真和数值结果显示:PB发射功率、时隙切换因子、天线数目、功率分配因子等参数对系统中断概率和吞吐量性能影响显著;当给定PB发射功率为6 dBW,天线数目为3根时,与随机中继选择算法和最大最小中继选择算法相比,本文算法在SC策略下的系统吞吐量增益分别为0.29、0.15 bit/(s·Hz),MRC策略下的吞吐量增益分别为0.32、0.16 bit/(s·Hz).

基于象限分割的迟滞软切换VLC-WiFi接入选择算法

针对解决无线网络频谱匮乏、用户频繁切换问题,本文提出一种基于象限分割的VLC-WiFi异构接入与迟滞软切换算法。依照三维坐标系将室内分割为4部分建立用户速率模型,获取用户速率,建立遮挡模型模拟VLC链路被遮挡情景。用户依据所在位置、象限、遮挡及速率等参数执行接入操作;切换依据迟滞思想将向内切换与向外切换阈值差异化,使切换存在弹性空间从而抑制乒乓效应。在5 m×5 m×5 m室内空间内经过多次实验表明,提出的室内VLC-WiFi异构组网方案水平切换次数降低43.8%,遮挡及垂直切换数降低45.3%,乒乓次数降低52.27%,吞吐量比传统算法提升约5.84%。该算法可以显著降低切换与乒乓次数。因此本文为室内异构网络通信研究提供理论依据。

安全路由协议综合交互信任评价及性能分析

随着工业控制系统不断引入网络化技术,给网络安全带来了很大的压力。为了进一步提高安全路由抵御网络攻击的能力,将信任评估模型与两跳实时可靠路由协议THTP相结合,设计出一种建立在工业无线传感器网络节点上的安全路由协议NCS。利用推荐节点提供的推荐信任可靠度可以去除不可靠推荐节点,促进网络安全性的显著提升。研究结果表明:设计的方法具有更低的时延,更小计算复杂度,尤其是只适用于当恶意节点数量增加的情况。该研究可以有效提高网络受攻击情况下的信任平台建设,有助于提高网络安全。

An Improved Interconnection Network Based on NIN

The Novel Interconnection Network (NIN) based on inverted-graph topology and crossbar switch is a kind of lower latency and higher throughput interconnection network. But it has a vital disadvantage, high hardware complexity. In order to reduce system hardware cost, an improved NIN (ININ) structure is proposed. As same as NIN, ININ has constant network diameter. Besides of keeping advantages of NIN, hardware cost of ININ is lower than NIN. Furthermore, we design a new deadlock-free routing algorithm for the improved NIN. Key words NIN - ININ - inverted-graph interconnection network - hardware complexity - network band-width - network throughput CLC number TP 302 Foundation item: Supported by the National Natural Science Foundation of China (69873016)Biography: Li Fei (1974-), male, Ph. D candidate, research direction: architecture of interconnection network.

STUDY ON STRATEGY OF DYNAMIC JOINT ROUTING AND RESOURCE ALLOCATION IN LAYERED OPTICAL TRANSPORT NETWORKS

A layered network model for optical transport networks is proposed in this paper,which involves Internet Protocol(IP) ,Synchronous Digital Hierarchy(SDH) and Wavelength Division Mul-tiplexing(WDM) layers. The strategy of Dynamic Joint Routing and Resource Allocation(DJRRA) and its algorithm description are also presented for the proposed layered network model. DJRRA op-timizes the bandwidth usage of interface links between different layers and the logic links inside all layers. The simulation results show that DJRRA can reduce the blocking probability and increase network throughput effectively,which is in contrast to the classical separate sequential routing and resource allocation solutions.

室内VLC-WiFi异构网络中多色载波资源分配

可见光通信接入点(VLC AP)在室内密集部署的方式在扩大VLC-WiFi系统容量的同时,增加了覆盖的小区间干扰。为了降低小区间干扰,提高系统的吞吐量和平均用户满意度,本文设计了多色载波分配与功率控制(MCAPC)的资源分配方法。该方法依据VLC AP的部署位置和信道特性,采用软频率复用方法确定各VLC AP的无干扰的主载波和多色副载波,并设计基于匹配博弈的载波和子频带分配算法为用户分配异构网络的频带资源;最后,设计基于功率控制效用值的干扰抑制的载波功率控制算法进一步抑制小区间干扰。研究结果表明,所提MCAPC方法能够提高室内多色VLC-WiFi异构网的系统吞吐量和用户的平均满意度。

粤北喀斯特地区不同年龄油茶林土壤细菌群落动态变化特征

[目的]明确油茶种植年限对喀斯特地区土壤微生物群落的影响。[方法]以乐昌市富树山油茶种植基地分别种植了2、3和7年的油茶林土壤为研究对象,利用高通量测序技术和分子生态网络的分析方法对土壤细菌群落进行研究。[结果]油茶种植年限的增加会导致土壤中铵态氮和总氮的积累,虽然不会显著改变土壤中细菌群落的生物多样性,但会导致土壤细菌群落结构的改变。同时发现土壤水分是影响2、3年龄油茶林土壤细菌群落的关键环境因子,而种植7年油茶林的土壤细菌群落主要受pH的影响。此外,相比种植2~3年的油茶林,种植7年的油茶林土壤细菌类群之间的联系更为紧密,但同时出现了细菌网络模块化的缺失和关键物种的演变的现象。[结论]本研究揭示了粤北石漠化地区不同种植年限油茶纯林的土壤细菌群落动态变化特征,为维持油茶林土壤生态系统功能的实践管理提供了理论依据。

基于光纤的传感物联网吞吐量最大化中继节点选择

中继节点是传感物联网通信的中转中心,其选择的合理性对保证物联网通信稳定和信息吞吐量具有重要意义。提出基于光纤的传感物联网吞吐量最大化中继节点选择方法。构建传感物联网模型,在平面中任意布局节点,利用所在点数据整合全部节点,在目标光纤传感器基站中找出主瓣,识别光源节点传输的信号。计算节点能量平均数,在自适应状态中将能量的分母最小化。在候选节点选取可将已知的光信道状态完整传输给其他节点的中继节点,基于统计独立分布获得系统平均接收信噪比,选择光纤传感器天线完成吞吐量最大化中继节点选择。仿真结果表明,所提方法在节点数量为22时的中断概率趋近于0;在光源节点功率30 dBm时,网络吞吐率达到98%。

面向中压直流配电网的模块化多电平电池储能系统电荷吞吐量抑制策略

模块化多电平电池储能系统(modular multilevel converter-battery energy storage system,MMC-BESS)中各子模块功率周期性波动,与其相连的电池组充放电状态频繁切换,产生额外的电荷吞吐量,危害电池储能系统寿命。当MMC-BESS用于中压直流配电网时,其交直流侧功率传输情况复杂多变,增大电荷吞吐量的抑制难度。因此,文中针对中压直流配电网中的MMC-BESS,提出一种基于二倍频环流注入的电荷吞吐量抑制策略。首先,构建中压直流配电网中MMC-BESS的数学模型;其次,剖析MMC-BESS电荷吞吐量的产生机理,分析不同运行方式下电荷吞吐量的影响因素;再次,提出基于二倍频环流注入的电荷吞吐量抑制策略,以系统总电荷吞吐量最小为目标,选取不同工况下需注入的最优二倍频环流分量;最后,多种工况下的仿真及实验结果表明,所提方法可有效抑制中压直流配电网中MMC-BESS的电荷吞吐量。

利用network coding的多速率多播最大吞吐量问题研究

本文研究了利用network coding的多速率多播最大吞吐量问题。与以往研究重点集中在单速率多播中的network coding研究工作不同,本文考虑了链路的异构性问题并采用多速率多播来解决该问题。首先文中形式化地描述了多速率多播最大可得吞吐量问题,并证明了在分层独立和层速率固定条件下,利用network coding的多速率多播最大吞吐量问题是NP-hard类问题,同时给出了最大吞吐量的上界。此外本文同时也研究了分层相关和层速率可变情况下的最大吞吐量问题。

基于隐马尔可夫模型的高速公路路由算法

在VANET高速公路场景中,由于车辆高速运动导致车辆和车辆、车辆和RSU之间所构成的网络拓扑频繁改变,使得绝大多数路由协议需要及时更新自己的邻居表来指定路由。针对邻居选择错误会导致数据不断重发、传输时延高且不可靠等现象,文章提出SDN-NDHM算法解决邻居选择错误的问题。算法利用典型的GPSR算法思想,运用HMM来预测高速运动节点的下一时刻位置信息,并且利用SDN来修正预测值、集中管理和调度网络资源。通过MATLAB的仿真实验表明,该算法与经典的GPSR改进算法相比能更好判断车辆节点的加入和离开,并且拥有更好的平均邻居正确率和更高的吞吐量。