LR-PON中改进的节能动态带宽分配算法

长距离无源光网络(Long-reach Passive Optical Networks,LR-PON)的覆盖范围超过100 km,光网络单元(Optical Network Units,ONU)在一个轮询周期中处于空闲状态的时间较长.如果使处于空闲状态的ONU进入低功耗(休眠或假寐)模式,可以降低ONU的能耗.基于此,文章提出一种改进的节能动态带宽分配算法.该算法通过改变ONU的调度顺序,使得ONU在上下行传输结束后能够立刻进入休眠状态,而无需等待授权帧的到达,从而延长ONU的休眠时间.仿真结果表明:所提出算法能够降低ONU能耗和下行数据包平均时延.     

5G网络中基于覆盖区域优先级的微基站休眠算法

随着5G移动通信技术日渐成熟，移动终端数量快速增长，5G无线通信系统基站密集能耗问题突出，提出一种微基站区域分级休眠算法。考虑微基站负载、站间距离、层间配合对微基站休眠的影响，宏基站与宏基站之间重叠覆盖区域中微基站状态转换次数少，优先休眠操作节能效果好。仿真结果表明，节能率为23%，能适应不同的网络规模，在大规模网络中节能效果更优越。     

基于不同移动模型的移动自组网多播路由协议性能研究

为了研究移动自组网中多播路由协议在不同移动模型下的性能,选取随机路点移动模型、高斯马尔科夫移动模型和参考点组移动模型,将三种移动模型的移动场景加入到NS2中,对基于部分网络编码的实时多播协议PNCRM进行仿真.结果表明,PNCRM协议在随机路点移动模型和高斯马尔科夫移动模型中的数据包投递率明显高于参考点组移动模型,但是参考点组移动模型的总开销和端到端延时是最优的.这样我们就可以根据不同的性能指标要求选择合适的移动模型.     

联合无线网络编码与TCP Vegas的多播协议优化研究

为解决移动自组网中网络编码多播路由协议因业务传输负载增大,而产生的网络拥塞现象,本文提出了一种可靠的基于TCP Vegas窗口拥塞控制的网络编码多播路由协议。该协议的核心思想是发送节点采用发送窗口自调整和反馈消息触发发送窗口调整的机制,综合的调节数据包的发送速率,来改善网络拥塞现象,从而可以降低丢包率。仿真结果表明,当传输负载增大时,基于窗口拥塞控制的网络编码多播路由协议可使得系统的总开销大大降低,分组投递率获得了相对的提升。     

一种基于网络编码的移动自组网实时多播协议

针对移动自组网中的实时多播场景,提出一种基于网络编码的协议—NCRM.该协议可通过减少网络中数据包的转发次数降低节点能耗,并可改善网络吞吐量性能.为适应实时性要求,在NCRM中引入了严格的时延限制机制.仿真结果显示,与PUMA、MAODV等传统协议相比较,NCRM能更好地适应存在多接收节点、高移动性的环境,且在传输可靠性与节省能耗方面具有显著优势.     

基于交叉流网络编码的节能路由

节能路由是无线自组织网络的一个重要研究课题,对延长网络生存时间极为重要。在传统路由下,多对节点之间通信使用的多条数据传递路径会出现交叉存在公共节点,这些公共节点因需要转发来自多条交叉路径的数据包而比其它节点消耗更多的能量,从而过早因能量耗竭而失效。为了克服这一能耗不均衡问题,该文提出基于网络编码的节能路由NCBEER (Network Coding Based Energy Efficient Routing),它可捕捉多条路径交叉的机会,让公共节点对所转发的数据包进行编码,然后把编码数据包多播(Multicast)邻居节点,以减少公共节点转发数据包次数从而降低能耗;推导了编码节点使全部接收节点接收到编码数据包所需要的平均多播次数,定义了无线链路的传输代价,并将之作为信源将流量分配给不同路径的依据。仿真试验表明,NCBEER可降低和均衡节点的能耗,且能够延长网络生存时间。     

一种适用于虚拟机网络的数据包高效传输方法

为了提高数据包在云计算数据中心中基于虚拟机构成网络中的传输性能,提出了一种基于网络编码的高效数据包传输方法.基于网络编码机制,采用对传输过程中丢失数据包高效的编码组合策略,多个虚拟机终端可以在一次多播或广播传输中获取多个从交换机优先传输的数据包,因此,提出的方法可以提高基于虚拟机网络的多播及广播业务的数据包传输延迟,并提高多播及广播业务的网络吞吐量.仿真结果表明提出的方法在典型信道条件下均获得了较好的数据包传输时延及网络吞吐量性能.     

虚拟网络映射高效节能运输模型及算法

网络虚拟化使得智能能量感知网络部署成为可能,已有研究忽略了节点映射能耗最优化。本文把节点映射能耗优化问题转化为生产地与销售地之间物资运输代价最优化问题,建立高效节能节点映射运输模型。根据最大元素法,提出了混合一阶段与两阶段映射算法,在链路映射的约束下找到节点分配最小能耗代价最优解;利用主动休眠策略,提出了基于运输模型的主动休眠虚拟网络映射节能算法;利用节点可重复映射技术,提出了基于运输模型的节点可重复映射算法,进一步提高了底层网络资源休眠数量。仿真结果验证了本文所提算法能够显著降低系统能耗,适合大规模高效节能虚拟网络映射。     

单兵电台网路MAC层节能方案设计

单兵电台作为战术互联网的末端通信设备,对续航能力有很高的要求。主要从减少通信模块的空闲侦听时间着手,设计了一种MAC层按需休眠与唤醒方案,并对方案进行了仿真。仿真结果表明,在全连通网络和三跳网络环境下,随着业务发送时间间隔的增大,网络在有休眠策略下所需的平均能耗比无休眠策略下的平均能耗明显降低,验证了方案的可行性。     

基于部分网络编码的移动自组网实时多播协议研究

传统网络编码可以减少数据包的转发次数,但会造成数据包较大的延时,且容易造成网络的拥塞.本文提出一种基于部分网络编码的实时多播协议——PNCRM.该协议将部分网络编码与mesh的建立结合在一起,有效地减小了端到端的延时,并且改善了网络吞吐量性能.仿真结果表明,与PUMA或基于传统网络编码的实时多播协议相比,PNCRM更好地适应接收节点较多、动态性较大的环境,且在数据包投递率及端到端的延时方面有着显著的优势.     

Performance evaluation of CSMA/ID MAC protocol for IP over WDM ring networks

In this paper, a packet pre‐classification media access control protocol based on a carrier sense multiple access with idle detection (CSMA/ID) scheme is investigated for supporting IP packets over all‐optical WDM ring networks. The purpose of the protocol is to increase throughput and to decrease the packet transmission delay of IP packets over optical networks in a metropolitan area network. This protocol avoids both packet collision and packet fragmentation. In order to improve the utilization of the network, the packets transmitted from a local area network are first pre‐classified into various class queues of an access point (AP) according to their length. After checking the available space based on the wavelength received by the receivers of the AP, the packets in the queues are transmitted. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency. The proposed network has short‐term variations that introduce unfairness conditions. This problem could be overcome by assigning a quota on individual queues to allow all queues fair access. Copyright © 2008 John Wiley & Sons, Ltd.     

C-PRMA: a centralized packet reservation multiple access for localwireless communications

Packet-switched technology has been demonstrated as effective in cellular radio systems with short propagation delay, not only for data, but also for voice transmission. In fact, packet voice can efficiently exploit speech on-off activity to improve bandwidth utilization over time division multiple access (TDMA). Such an approach has been first suggested in the packet reservation multiple-access (PRMA) technique, an adaptation of the reservation ALOHA protocol to the cellular environment. However, being PRMA-based on a fixed frame scheme, it cannot thoroughly take advantage of the very short propagation delays encountered in microcellular systems that allow, for instance, the immediate retransmission of packets lost because of the interference noise from adjacent cells. We present the centralized PRMA, a natural enhancement of PRMA, in which the base station (BS) plays a central role in scheduling the transmissions of mobile stations (MSs). As a consequence, the transmission scheduling is very flexible and can account for the different traffic rate and delay constraints that emerge from voice and data integration. A packet retransmission policy to recover corrupted packets can be implemented and operated efficiently to provide an acceptable grade of service, even in a very noisy environment. The simulation results presented show the quantitative improvements of the centralized packet reservation multiple-access (C-PRMA) performance with respect to PRMA     

Dynamic traffic-aware routing algorithm for multi-sink wireless sensor networks

In this paper, a distributed traffic-balancing routing algorithm is proposed for multi-sink wireless sensor networks that effectively distributes traffic from sources to sinks. Each node has a gradient field that is used to decide on a neighbor node to reach a sink. The node’s gradient index contains (1) the distance cost from a source to a respective sink, and (2) traffic information from neighboring nodes. The proposed algorithm considers the traffic being faced by surrounding neighbors before forwarding packets to any sink using gradient search for routing and providing a balance between optimal paths and possible congestion on routes toward those sinks. The key objective of this work is to achieve traffic-balancing by detecting congested areas along the route and distributing packets along paths that have idle and underloaded nodes. Extensive simulations conducted to evaluate the performance of the proposed scheme indicate that it effectively reduces the overall packet delay, energy consumption and improves the packet delivery ratio under heavy traffic.     

A channel reuse strategy with adaptive channel allocation for all-optical WDM networks

The fundamental problems of WDM networks are: (1) high rate of control packet loss and (2) high propagation delay for each (re)transmission. In this paper, we minimize the station randomness to access the control architecture introducing a collisions-free access scheme. We propose a synchronous protocol according which at the end of the propagation delay each station applies a distributed algorithm for packet transmission following the data channel collisions and the receiver collisions avoidance algorithms. We introduce two data transmission stages. The time difference between them is one packet transmission time. At the end of the first stage all data channels are free and can be reused by the remaining data packets during the second stage. The proposed protocol ensures a totally collisions-free performance. The main advantage is that the data channels reuse strategy applied during the second stage provides enhanced transmission probability to the rejected packets during the first stage. This allows the data packets to try retransmission in the same cycle without requiring control packets re-coordination that increases propagation delay. Thus, we achieve large number of data packets transmission, even more than the data channels number, providing throughput improvement and delay reduction, comparing with other studies.     

NER-DRP: Dissemination-based Routing Protocol with Network-layer Error Control for Intermittently Connected Mobile Networks

Reliable transmission in Intermittently Connected Mobile Networks (ICMNs) is a challenging work because the effective and reliable connection between the source and the destination can not be sustained. To reliably hand over data packets to the destination, many dissemination-based routing protocols are proposed. Dissemination-based routing protocols assure nodes including intermediate nodes and destinations have more chances to receive packets, which will increase the probability that the packets can be correctly received by the destination. However, the existing error recovery mechanisms in network layer use the simple CRC to check the data packets independently, and discard the error packets even if one correct packet can be obtained from more than one partly error packets. In this paper, first we propose a novel Network layer Error Recovery method (abbreviated as NER) based on Forward Error Correction (FEC). NER divides a data packet into Reed Solomon (RS) blocks and insert redundancy to each block. So the intermediate nodes and destinations can recover a correct data packet from multiple partially error copies of the same packet. Then we propose a novel routing protocol named NER-DRP based on the Epidemic routing and NER, which can improve the performance of ICMNs in terms of delivery ratio, end-to-end delay and count of hops.     

Optimized Congestion Management Protocol for Healthcare Wireless Sensor Networks

The application of Wireless Sensor Networks (WSNs) in healthcare is dominant and fast growing. In healthcare WSN applications (HWSNs) such as medical emergencies, the network may encounter an unpredictable load which leads to congestion. Congestion problem which is common in any data network including WSN, leads to packet loss, increasing end-to-end delay and excessive energy consumption due to retransmission. In modern wireless biomedical sensor networks, increasing these two parameters for the packets that carry EKG signals may even result in the death of the patient. Furthermore, when congestion occurs, because of the packet loss, packet retransmission increases accordingly. The retransmission directly affects the lifetime of the nodes. In this paper, an Optimized Congestion management protocol is proposed for HWSNs when the patients are stationary. This protocol consists of two stages. In the first stage, a novel Active Queue Management (AQM) scheme is proposed to avoid congestion and provide quality of service (QoS). This scheme uses separate virtual queues on a single physical queue to store the input packets from each child node based on importance and priority of the source’s traffic. If the incoming packet is accepted, in the second stage, three mechanisms are used to control congestion. The proposed protocol detects congestion by a three-state machine and virtual queue status; it adjusts the child’s sending rate by an optimization function. We compare our proposed protocol with CCF, PCCP and backpressure algorithms using the OPNET simulator. Simulation results show that the proposed protocol is more efficient than CCF, PCCP and backpressure algorithms in terms of packet loss, energy efficiency, end-to-end delay and fairness.     

ARMS-EGR—Adaptive ranking and mobile sink-enabled energy-efficient geographic routing protocol in flying ad hoc networks

Unmanned aerial vehicles (UAVs) have become widespread because of their involvement in a variety of applications. The task of designing the energy-efficient routing between UAVs has been considered a matter of great interest due to the inherent challenges of controlling the dynamics exhibited by UAVs. Energy limitations are considered the main limitations of UAVs. This research paper proposes a novel routing protocol, adaptive ranking and mobile sink (MS)-enabled energy-efficient geographic routing (ARMS-EGR) for flying ad hoc networks. In ARMS-EGR, the whole network is partitioned into cells. The cell contains cell members (CM) and cell heads (CHs). The CH works as a cluster head. Additionally, two MSs have been used to collect data captured by CM. Multihop communication on the network leads to an increase in traffic and consumes the energy of the UAVs located near the base station (BS). MSs are used for power distribution and load balancing across the network. Adaptive ranking of forwarder UAVs and CHs is performed during intracell and intercell multihop communication, respectively, using adaptive ranking. A cell with one-hop communication can directly send packets to the MS, but the ARMS-EGR routing protocol has been proposed for multihop communication. The proposed approach is simulated in NS-2.35 software. The results show that end-to-end latency and power consumption during packet transmission are greatly minimized. ARMS-EGR also demonstrates improvements in message success rates, number of alive nodes, and packet delivery ratio, making ARMS-EGR particularly suitable for flying ad hoc networks (FANETs).     

EMA-PRBDS: efficient multi-attribute packet rank based data scheduling in wireless sensor networks for real-time monitoring systems

ABSTRACT

In recent years, Wireless Sensor Networks (WSNs) are widely placed in real-time monitoring systems like environmental, structural, patient monitoring, etc. The major criterion for WSN includes energy efficiency and network lifetime. Scheduling is used as a large number of data packets focus on the same queue at the same time. Only limited data scheduling schemes have been implemented in WSN to enhance the performance. The existing First Come First Serve (FCFS) and Dynamic Multilevel Priority (DMP) have some technical challenges like delay, packet drop and high energy consumption due to starvation and deadlock. In this paper, we proposed a new algorithm to optimise and rank the incoming data packets based on multi-attributes decision-making methodology named as Packet Rank Based Data Scheduling (PRBDS), the algorithm selects packet priority, deadline, and size as the metrics to rank the incoming data packets. A simulation result shows when compared with existing scheduling, PRBDS not only provides less energy consumption, also significantly reduces the packet drop and increases the lifetime. Thus, the proposed algorithm is most suitable for real-time monitoring system since it combines data ranking method with scheduling algorithm to create accurate and reliable results to evaluate the incoming data packets.     

Optimal energy-delay tradeoff for opportunistic spectrum access in cognitive radio networks

Cognitive radio (CR) has been considered as a promising technology to enhance spectrum efficiency via opportunistic transmission at link level. Basic CR features allow secondary users (SUs) to transmit only when the licensed channel is not occupied by primary users (PUs). However, waiting for an idle time slot may lead to large packet delays and high energy consumption. We further consider that the SU may decide, at any moment, to use another dedicated way of communication (4G) in order to transmit his packets. Thus, we consider an Opportunistic Spectrum Access (OSA) mechanism that takes into account packet delay and energy consumption. We formulate the OSA problem as a Partially Observable Markov Decision Process (POMDP) by explicitly considering the energy consumption as well as packets’ delay, which are often ignored in existing OSA solutions. Specifically, we consider a POMDP with an average reward criterion. We derive structural properties of the value function and we show the existence of optimal strategies in the class of the threshold strategies. For implementation purposes, we propose online learning mechanisms that estimate the PU activity and determine the appropriate threshold strategy on the fly. In particular, numerical illustrations validate our theoretical findings.     

Energy efficient transmission scheduling for delay constrained wireless networks

In this paper, we address the problem of energy efficient packet scheduling in a wireless environment. We consider a wireless transmitter which is limited by its finite battery resource. Our objective is to design a transmission schedule that maximizes battery lifetime subject to some delay constraints. To achieve this, we exploit two previously unconnected ideas: (i) channel coding can be used to conserve energy by transmitting at reduced power levels over longer durations; (ii) electro-chemical mechanisms in batteries allow them to recover energy during idle periods. While the first idea favors extending transmission durations, the second idea requires the transmitter to be idle to allow for recovery. In other words, bursty packet transmissions interspersed with idle periods extend battery life. Therefore, a strategy which is based entirely on either one or the other idea is not optimal. We provide a framework to merge the two ideas. We consider two kinds of delay constraints, one a deadline constraint and the other an average delay constraint and show that energy aware scheduling strategies for both these scenarios can result in significant energy savings.