Fine grained load balancing in multi-hop wireless networks

In this paper we address the problem of local balancing in multi-hop wireless networks. We introduce the notion of proactive routing: after a short pre-processing phase in which nodes build their routing tables by exchanging messages with neighbors, we require that nodes decide the relay of each message without any further interaction with other nodes. Besides delivering very low communication overhead, proactive routing protocols are robust against some well known active attacks to network routing. In this framework, we develop a proactive routing protocol that is able to balance the local load. Experiments show that our protocol improves network lifetime up to 98% and that it delivers a network that is more robust against attacks that have the goal of getting control over a large part of the network traffic.     

一种用于无线传感器网络的新联合优化算法

提出了一种跨MAC层和网络层的联合设计算法（IMR）,用于解决无线传感器网络中节约能量的问题。它能够迅速地对于频发性事件做出感知和报告,同时把能量消耗控制在一个较低的水平。IMR算法把一个监控区域划分为有一个汇聚节点的层次结构,以汇聚节点为中心进行数据传输。处于远端的节点通过不同层的中继节点将信息传输到汇聚节点。仿真结果表明,和S-MAC协议相比,提出的方法在节约能量方面明显优于前者。     

无线传感器网络媒质接入控制协议的研究进展

媒质接入控制（Medium Access Control）是无线传感器网络设计的关键问题之一。由于无线通信模块是传感器节点能量消耗的主要来源,而媒质接入控制协议则直接控制着节点无线通信模块的活动,因此MAC协议节能效率的好坏将严重影响网络的性能。本文首先介绍了MAC层能量消耗的主要来源,阐述了无线传感器网络中MAC协议的研究内容和设计目标,并讨论了影响MAC协议性能的若干参数指标,随后介绍了几类典型的MAC协议,最后对MAC协议的发展方向进行了总结和展望。     

基于最短路径树的分布式功率控制路由算法

当节点不能获知与邻居节点的距离时,为解决节点能量消耗过快而过早失效,从而减少网络生存时间的问题,提出基于最短路径树的分布式功率控制路由算法(DPCRA_SPT)。该算法综合考虑网络中节点间传输数据的能耗和邻居节点的剩余能量,引入新的权值函数和功率线性衰减模型。运用分布式非同步Bellman-Ford算法构建最短路径树,所有节点沿着最短路径树将数据汇集到Sink节点。仿真结果表明:在密集分布的无线传感网中,通过调整参数,DPCRA_SPT算法可以延长网络生存时间,将能耗保持在较低的水平。在一定的条件下,DPCRA_SPT算法比Ratio_w_FTP、BFFTP、BFSAM、BFPAM算法更优。     

基于工作周期优化的能量采集节点的功率控制

在无线传感网络WSNs(Wireless Sensor Networks)中,节点受到能量限制,因此,需通过功率管理技术有效地使用电池.而能量采集是补给电池能量的有效方式.为此,针对能量采集节点,提出功率控制算法,记为CLPM-PTPC(Close-Loop Power Manager-Predictive Transmission Power Controller).CLPM-PTPC算法是通过联合工作周期的优化和传输功率控制,实现节点功率的管理.CLPM-PTPC算法先利用闭环功率管理CLPM(Close-Loop Power Manager)调整传输任务的工作时期,再依据功率控制器PTPC(Predictive Transmission Power Controller)调整发射功率,使得传输功率能够实时地依据无线信道环境调整.实验数据表明,与基于固定传输功率算法相比,CLPM-PTPC算法的能量效率提高了约15％.     

Modelling and performance analysis of multi-hop ad hoc networks

Mobile ad hoc networks are becoming very attractive and useful in many kinds of communication and networking applications. Due to the advantage of numerical analysis, analytical modelling formalisms, such as stochastic Petri nets, queuing networks and stochastic process algebra have been widely used for performance analysis of communication systems. To the best of our knowledge, there is no previous analytical study that analyses the performance of multi-hop ad hoc networks, where mobile nodes move according to a random mobility model in terms of the end-to-end delay and throughput. This work presents a novel analytical framework developed using stochastic reward nets for modelling and analysis of multi-hop ad hoc networks, based on the IEEE 802.11 DCF MAC protocol, where mobile nodes move according to the random waypoint mobility model. The proposed framework is used to analyse the performance of multi-hop ad hoc networks as a function of network parameters such as the transmission range, carrier sensing range, interference range, number of nodes, network area size, packet size, and packet generation rate. The proposed framework is organized into several models to break up the complexity of modelling the complete network, and make it easier to analyse each model as required. The framework is based on the idea of decomposition and fixed point iteration of stochastic reward nets. The proposed models are validated using extensive simulations.     

Energy-aware routing in the Cognitive Packet Network

An energy aware routing protocol (EARP) is proposed to minimise a performance metric that combines the total consumed power in the network and the QoS that is specified for the flows. The algorithm uses source routing based on the functionalities provided by the Cognitive Packet Network (CPN), running autonomously at each input node to the network based on smart packets which gather relevant information throughout the network using reinforcement learning at each of the intermediate nodes. Measurements on an experimental test-bed that uses EARP are presented and they indicate that it offers a reduction in power consumption, as compared to a purely QoS driven approach, and also respects the requested QoS level.     

无线Ad Hoc网络中的功率控制问题

分析了Adhoe网络中节点的能量消费模式,详细论述了几种MAC层的功率控制技术和网络层具有能量意识的路由的主要度量准则,并提出了一些有前景的研究方法。     

A power efficiency routing and maintenance protocol in wireless multi-hop networks

In wireless multi-hop networks, selecting a path that has a high transmission bandwidth or a high delivery rate of packets can reduce power consumption and shorten transmission delay during data transmission. There are two factors that influence the transmission bandwidth: the signal strength of the received packets and contentions in the contention-based MAC layer. These two factors may cause more power to be consumed during data transmission. We analyze these two factors and propose a power-aware routing protocol called MTPCR. MTPCR discovers the desired routing path that has reduced power consumption during data transmission. In addition to finding a desired path to reduce power consumption, MTPCR also takes into account the situations in which the transmission bandwidth of the routing path may decrease, resulting in much power consumption during data transmission because of the mobility of nodes in a network. MTPCR is thus useful in a network: it analyzes power consumption during data transmission with the help of neighboring nodes, and it uses a path maintenance mechanism to maintain good path bandwidth. The density of nodes in a network is used to determine when to activate the path maintenance mechanism in order to reduce the overhead of this mechanism. With the proposed path maintenance mechanism, power consumption during data transmission can be efficiently reduced, as well as the number of path breakages. In our simulation, we compared our proposed routing protocol, MTPCR, with the following protocols: two classical routing protocols, AODV and DSR; two power-aware routing protocols, MMBCR and xMBCR; and one multiple path routing protocol, PAMP. The comparisons are made in terms of throughput of the routing path, power consumption in path discovery, power consumption in data transmission, and network lifetime.     

认知无线电网络分布式多信道MAC协议*

在认知无线电网络中,MAC协议用于信道感知、选择和接入控制。以单网卡多信道MAC（MMAC）协议为基础,依据IEEE 802.22标准定义的静默期管理的两阶段感知策略,提出一种认知无线电网络分布式多信道MAC（CR-MMAC）协议。将两阶段感知机制和分布式协商融入MMAC协议,利用空闲频谱进行数据传输,并在MMAC协议ATIM窗的数据信道协商阶段引入预约机制,以避免选择同一信道的认知节点对在后续数据传输阶段再利用CSMA/CA造成的竞争碰撞。仿真对比分析表明,CR-MMAC协议能提高网络吞吐量、降低通信时     

基于有效传输的能量敏感的路由协议

能量敏感是传感器网络设计中的一个基本要求,现有的基于位置的路由协议都没有考虑下一跳节点与源节点的距离,使得传输效率不高。本文通过引入有效传输（ET）概念保证每个前向节点比其前驱节点不仅更加靠近目标节点,而且更加远离源节点,提出一种基于ET的能量敏感的路由协议。仿真结果表明这种路由协议与其它一些协议比较起来,可以提供较低的能量消耗。     

异质网络传输控制技术研究

分析了无线链路的特点及其对TCP性能的影响,讨论和评价了现存的各种异质网络数据传输控制机制,最后指出该领域的研究动向及进一步的工作。     

On supporting high-throughput routing metrics in on-demand routing protocols for multi-hop wireless networks

Researchers have proposed routing metrics other than hop count, such as ETX (expected transmission count) and ETT (expected transmission time), to find routes with high throughput. These metrics are inherently suitable to be used in source routing protocols such as DSR, because link state information needs to be collected for the calculation of the shortest path. In this paper, we propose an efficient and generalized approach called accumulated path metric (APM) for supporting high-throughput metrics (HTMs) in on-demand routing protocols. One advantage of APM is that it is able to find the shortest path, in terms of a particular metric, without collecting topology information and without running a shortest-path algorithm. This will significantly simplify the existing design of supporting HTMs in DSR. We present a proof of the correctness of APM. Moreover, we address the problem of duplicate RREQ (route request) transmissions with existing HTM schemes and present a broadcast ordering (BO) technique to suppress unnecessary RREQ transmissions. We study the performance of APM and BO in both AODV and DSR, and the results verify the effectiveness of the proposed approaches.     

无线工业控制网络中的时间同步研究

针对无线工业控制网络WICN的特点,分析RBS和TPSN时间同步算法的不足。利用基于令牌的MAC协议,提出一种适用于无线工业控制网的时间同步算法WICNTS,该算法采用MAC层记录时戳的方式进行成对同步。然后给出了模型的建立过程,并用离散事件仿真平台OMNeT++对该协议进行仿真实验,仿真结果表明该算法能满足WICN网络的时间同步要求。     

NOMA系统异构网络中联合用户关联和功率控制协同优化

针对非正交多址接入(Non-Orthogonal Multiple Access,NOMA)系统的两层异构网络,提出了基于效用函数最大化模型的用户关联与功率控制协同优化问题.在该问题中将系统总能效作为效用函数,在一定的用户服务质量要求(QoS)和最大功率限制约束下,提出一种联合用户关联和功率控制的算法.该算法首先将原问...     

Performance analysis of ad-hoc routing in heterogeneous clustered multi-hop wireless networks

This paper analyzes the performance of clustered decode-and-forward multi-hop relaying (CDFMR) wireless Rayleigh fading networks, and sheds light on their design principles for energy and spectral efficiency. The focus is on a general performance analysis (over all SNR range) of heterogeneous wireless networks with possibly different numbers of relays in clusters of various separations. For clustered multi-hop relaying systems, hop-by-hop routing is known as an efficient decentralized routing algorithm which selects the best relay node in each hop using local channel state information. In this article, we combine hop-by-hop routing and cooperative diversity in CDFMR systems, and we derive (i) a closed-form expression for the probability distribution of the end-to-end SNR at the destination node; (ii) the system symbol error rate (SER) performance for a wide class of modulation schemes; and (iii) exact analytical expressions for the system ergodic capacity, the outage probability and the achievable probability of the SNR (power) gain. We also provide simple analytical asymptotic expressions for SER and the outage probability in high SNR regime. Numerical results are provided to validate the correctness of the presented analyses.     

Extending network lifetime for ALLIANCES

ALLIANCES is a newly proposed wireless MAC protocol that exploits the cooperation of source nodes and relay nodes to resolve collisions and further improve throughput. Until now, ALLIANCES did not consider energy, which is the most precious commodity of mobile communications. In this paper, we propose an energy-conserving version of ALLIANCES that introduces a sleep state. Our analytical results show that the energy-conserving model can save at least 54% of energy consumption when compared to the original energy model (referred to as the basic energy model in this paper). Because a relay selection scheme is a significant piece of ALLIANCES, directly affecting the throughput and the energy distribution, we also propose an energy-aware relay selection scheme (ERS). ERS maintains the performance benefits of the previously proposed location relay selection scheme (LRS), but more evenly distributes the amount of energy remaining throughout the network. We implement our energy-conserving model and ERS in the popular network simulator (NS-2) to evaluate and compare the energy remaining at each node and the network’s throughput when using LRS and ERS. Simulation results show that the energy-conserving model can save up to 80% of energy without nodes taking longer to communicate. In addition, using the energy-conserving model, ERS provides 23.3% longer lifetime of the network than LRS, without noticeable throughput degradation.     

电力线数据传输系统设计

利用原有的低压电力网进行数据传输与控制，可广泛应用于家庭和办公室的智能化，经济方便。本文设计一种适应我国电网特性的通用型电力线数据传输系统，该系统为半双工、异步模式，采用双音多频调制，数据传输率40bps。实际应用表明该系统性能良好。     

智能电源控制系统的研制

文章介绍了用计算机及网络远程控制各种设备的电源，其中给出控制软件、接口及控制电路、网络的设计制作。控制系统简单可靠，实现了分散设备的智能集中管理。系统易于扩展功能，能满足日益发展的自动化管理的需要。     

多速率无线Mesh网络环境下功率控制与调度机制——PSMR

传输功率控制（TPC）技术是提高无线网络性能的关键技术之一。针对无线Mesh网络（WMN）的特点,提出了一种在多速率WMN环境下功率控制与调度机制（PSMR）,该机制以系统的吞吐率和公平性为目标,利用冲突图思想对网络进行分析,建立了多目标规划的数学模型,并采用微分进化算法对其进行求解。模拟测试表明,PSMR能有效提高系统吞吐率,改善系统的公平性。