Burstiness-Aware Congestion Control Protocol for Wireless Sensor Networks

In monitoring Wireless Sensor Networks(WSNs),the traffic usually has bursty characteristics when an event occurs.Transient congestion would increase delay and packet loss rate severely,which greatly reduces network performance.To solve this problem,we propose a Burstiness-aware Congestion Control Protocol(BCCP) for wireless sensor networks.In BCCP,the backoff delay is adopted as a congestion indication.Normally,sensor nodes work on contention-based MAC protocol(such as CSMA/CA).However,when congestion occurs,localized TDMA instead of CSMA/CA is embedded into the nodes around the congestion area.Thus,the congestion nodes only deliver their data during their assigned slots to alleviate the contention-caused congestion.Finally,we implement BCCP in our sensor network testbed.The experiment results show that BCCP could detect area congestion in time,and improve the network performance significantly in terms of delay and packet loss rate.

A Routing Protocol for Wireless Sensor Networks with Congestion Control

This paper proposed a novel RED protocol which takes the node’s energy into account depending on the length of the data packet. It also proposed a routing protocol for wireless sensor networks with congestion control which imitates the ant colony foraging behavior. Sensor nodes choose routings according to the pheromone density. The experiment result shows that the algorithm balances the energy consumption of each node. It mitigated congestion effectively with the proposed routing protocol.

Improved Bat Algorithm Based Energy Efficient Congestion Control Scheme for Wireless Sensor Networks

Energy conservation and congestion control are widely researched topics in Wireless Sensor Networks in recent years. The main objective is to develop a model to find the optimized path on the basis of distance between source and destination and the residual energy of the node. This paper shows an implementation of nature inspired improved Bat Algorithm to control congestion in Wireless Sensor Networks at transport layer. The Algorithm has been applied on the fitness function to obtain an optimum solution. Simulation results have shown improvement in parameters like network lifetime and throughput as compared with CODA (Congestion Detection and Avoidance), PSO (Particle Swarm Optimization) algorithm and ACO (Ant Colony Optimization).

On Approaches to Congestion Control over Wireless Networks

Congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless net-work. With the rapid expansion and implementation of wireless technology it is essential that the congestion control problem be solved. This paper presents a survey of five congestion control schemes which are dif-ferent in slow start threshold calculation, bandwidth estimation, and congestion window manipulation. A comprehensive comparison of these approaches is given in relation to assumptions, bandwidth estimation, congestion window size manipulation, performance evaluation, fairness and friendliness and improved throughput.

COCM: Class Based Optimized Congestion Management Protocol for Healthcare Wireless Sensor Networks

Wireless Sensor Networks (WSNs) consist of numerous sensor nodes which can be used in many new emerging applications like healthcare. One of the major challenges in healthcare environments is to manage congestion, because in applications, such as medical emergencies or patients remote monitoring, transmitted data is important and critical. So it is essential in the first place to avoid congestion as much as possible and in cases when congestion avoidance is not possible, to control the congestion. In this paper, a class based congestion management protocol has been proposed for healthcare applications. We distinguish between sensitive, non-sensitive and control traffics, and service the input traffics based on their priority and quality of service requirements (QoS). The proposed protocol which is called COCM avoids congestion in the first step using multipath routing. The proposed AQM algorithm uses separate virtual queue's condition on a single physical queue to accept or drop the incoming packets. In cases where input traffic rate increases and congestion cannot be avoided, it mitigates congestion by using an optimized congestion control algorithm. This paper deals with parameters like end to end delay, packet loss, energy consumption, lifetime and fairness which are important in healthcare applications. The performance of COCM was evaluated using the OPNET simulator. Simulation results indicated that COCM achieves its goals.

Energy-Efficient and Reliable Transport Protocols for Wireless Sensor Networks: State-of-Art

New wireless sensor network applications (e.g., military surveillance) require higher reliability than a simple best effort service could provide. Classical reliable transport protocols like Transmission Control Protocol (TCP) are not well suited for wireless sensor networks due to both the characteristics of the network nodes (low computing power, strong energy constraints) and those of the main applications running on those nodes (low data rates). Recent researches present new transport protocols for wireless sensor networks providing various type of reliability and using new mechanisms for loss detection and recovery, and congestion control. This paper presents a survey on reliable transport protocol for WSNs.

A WIRELESS MULTIMEDIA TRANSMISSION CONTROL AlGORITHM OVER HETEROGENEOUS IP NETWORKS

In this paper,an algorithm Wireless Multimedia Transmission Control(WMTC) is proposed for multimedia transmission control over wired-wireless networks.The relationship between packet length and packet loss rate in the Gilbert wireless error model is investigated.Furthermore,the algorithm can detect the nature of packet losses by sending large and small packets alternately,and control the sending rate of nodes.In addition,by means of updating factor K,this algorithm can adapt to the changes of network states quickly.Compared with previous algorithms,simulation results show that WMTC can both improve the networks throughput of multimedia transmissions and reduce the congestion loss rate in various situations.

Wireless Hybrid QoS Architecture with an Enhancement of Fair Intelligent Congestion Control

More subtle and explicit QoS control mechanisms are required at the radio access level, even though the simple and scalable Differentiated Services (DiffServ) QoS control model is acceptable for the core of the network. At the radio access level, available resources are severely limited and the degree of traffic aggregation is not significant, thus rendering the DiffServ principles less effective. In this paper we present a suitable hybrid QoS architecture framework to address the problem. At the wireless access end, the local QoS mechanism is designed in the context of IEEE 802.11 WLAN with 802.11e QoS extensions;so streams of those session-based applications are admitted, established according to the traffic profile they require, and guaranteed. As the core in the Admission Control of the hybrid QoS architecture, the Fair Intelligent Congestion Control (FICC) algorithm is applied to provide fairness among traffic aggregates and control congestion at the bottleneck interface between the wireless link and the network core via mechanisms of packet scheduling, buffer management, feedback and adjustments. It manages effectively the overloading scenario by preventing traffic violation from uncontrolled traffic, and providing guarantee to the priority traffic in terms of guaranteed bandwidth allocation and specified delay.

Novel congestion control approach in wireless multimedia sensor networks

Data generated in wireless multimedia sensor networks （WMSNs） may have different importance and it has been claimed that the network exert more efforts in servicing applications carrying more important information. Nevertheless, importance of packets cannot generally be accurately represented by a static priority value. This article presents a dynamic priority based congestion control （DPCC） approach that makes two major innovations in WMSNs. First, DPCC employs dynamic priority to represent packet importance. Second, it prioritizes the local traffic of motes near the base station when WMSN is highly congested. Simulation results confirm the superior performance of the proposed approach with respect to energy efficiency, loss probability and latency as well.

Congestion avoidance, detection and alleviation in wireless sensor networks

Congestion in wireless sensor networks (WSNs) not only causes severe information loss but also leads to excessive energy consumption. To address this problem, a novel scheme for congestion avoidance, detection and alleviation (CADA) in WSNs is proposed in this paper. By exploiting data characteristics, a small number of representative nodes are chosen from those in the event area as data sources, so that the source traffic can be suppressed proactively to avoid potential congestion. Once congestion occurs inevitably due to traffic mergence, it will be detected in a timely way by the hotspot node based on a combination of buffer occupancy and channel utilization. Congestion is then alleviated reactively by either dynamic traffic multiplexing or source rate regulation in accordance with the specific hotspot scenarios. Extensive simulation results under typical congestion scenarios are presented to illuminate the distinguished performance of the proposed scheme.

Jointly optimized congestion control, forwarding strategy,and link scheduling in a named-data multihop wireless network

As a promising future network architecture, named data networking(NDN) has been widely considered as a very appropriate network protocol for the multihop wireless network(MWN). In named-data MWNs, congestion control is a critical issue. Independent optimization for congestion control may cause severe performance degradation if it can not cooperate well with protocols in other layers. Cross-layer congestion control is a potential method to enhance performance. There have been many cross-layer congestion control mechanisms for MWN with Internet Protocol(IP). However, these cross-layer mechanisms for MWNs with IP are not applicable to named-data MWNs because the communication characteristics of NDN are different from those of IP. In this paper, we study the joint congestion control, forwarding strategy, and link scheduling problem for named-data MWNs. The problem is modeled as a network utility maximization(NUM) problem. Based on the approximate subgradient algorithm, we propose an algorithm called ‘jointly optimized congestion control, forwarding strategy, and link scheduling(JOCFS)'to solve the NUM problem distributively and iteratively. To the best of our knowledge, our proposal is the first cross-layer congestion control mechanism for named-data MWNs. By comparison with the existing congestion control mechanism, JOCFS can achieve a better performance in terms of network throughput, fairness, and the pending interest table(PIT) size.

Integral sliding-mode robust observer-based congestion control for wireless access networks

Designing a robust active queue management(RAQM)is mandatory to avoid congestion in networks with wireless access links,because transmission control protocol(TCP)can detect con-gestion after its occurrence in a communication network and wireless links suffer from bottleneck capacity variations caused by fading and packet error rate(PER)in the acknowledgement pack-ets.Furthermore,the average window size cannot be measured explicitly from the output signal and input and state delay are imposed to a network,which complicate theRAQMdesign problem in nonlinear models.So,the main contribution of this study is to design a robust observer based control procedure based on integral sliding mode protocol to estimate the average window size,to control congestion in a TCP/RAQM network and to compensate input and state delay.Sim-ulation results via professional simulator NS-2 and SIMULINK confirm that the procedure can effectively estimate the window size and can robustly avoid congestion.

无线传感网络拥塞控制中节点选择强制博弈方法

无线传感网络中节点数据流量较大,分布范围较广,节点选择寻优计算复杂,导致浪费大量算力在节点选择上,拥塞控制效果不佳。提出一种无线传感网络拥塞控制中节点选择强制博弈方法,计算单条网络链路传输成本,依据传输数据耗费能量,计算传输节点可用能量比值,在传输变量权重值基础上,求得传输节点实际拥堵指数,完成节点选择。计算网络连接层的数据包丢弃概率,确定网络拥塞程度,汇聚节点数据流建立节点选择强制博弈模型,明确传感网络稳态传输条件,利用流量正态分布算法,在节点选择博弈中做出强制选择。经仿真分析证明:所提方法分组递交率保持在83%以上,丢包数量保持在100 pkt/s之内,网络传输节点端到端的延迟在0.3 s以内。

无线局域网应用多重USG防火墙的安全策略研究

无线网络是一种方便灵活的网络接入方式,同时也存在一系列的安全威胁。通过对无线网络中可能产生的攻击和入侵方式进行详细的研究,确定基于华为USG5500防火墙的多重综合防御措施,包括身份验证、访问控制、数据加密、监测防御等多个方面,重点放在无线网络的身份验证和访问控制上。基于eNSP平台部署仿真拓扑,规划IP地址和防火墙区域,在无线网络中采用WPA2-PSK加密技术和VLAN技术,在多重防火墙中设置访问控制策略和流量过滤规则。仿真结果表明,在正确设置策略规则的情况下,多重USG5500防火墙能够及时监控和识别网络中的异常行为,有效检测和阻止网络攻击,提升无线网络的安全性和可靠性。

嵌入式技术下无线传感通信网络拥塞控制系统

无线传感通信网络在数据传输过程中容易出现网络拥塞,存在全局吞吐量小、端到端延时大、节点丢包率高的问题,导致网络拥塞控制效果不佳。为了解决这个问题,设计一种嵌入式技术下无线传感通信网络拥塞控制系统。设计嵌入式以太网拥塞数据交换接口电路,采用嵌入缓冲器开环控制模块结构,根据排队长度变化控制数据包丢弃率。计算接收方通告窗口大小,检测高、低优先级传输网络拥塞情况。通过计算拥塞节点发送速率来控制高、低优先级传输网络局部拥塞。将全局拥塞竞争窗口变为当前窗口,使用检测缓存队列占空率方式控制全局拥塞。测试结果表明,所设计系统最大吞吐量为2600 b/s,最大端到端延时为18 s,最大节点丢包率为2.0%,使用该系统能够提升网络拥塞控制效果。

面向智算中心的新型以太网需求与关键技术

AI大模型正引领下一个十年的信息与通信技术(information and communications technology,ICT)产业发展热点。智算中心网络是支撑AI大模型分布式训练的通信底座,是决定AI集群效能的关键要素之一。AI大模型的数据量和参数量不断扩张,给智算中心网络带来了严峻的挑战,同时给关键网络技术进行代际性创新带来了机遇。在AI大模型训练和推理过程中,提供数据的高性能和高安全传输是AI业务对智算中心网络的两大核心需求。高效的负载均衡、拥塞控制技术和网络安全协议是其中的关键网络技术。为应对大规模AI业务带来的严峻挑战,提出全调度以太网(global scheduled Ethernet,GSE)作为对应的解决方案,并搭建真实的测试环境对GSE和RoCE(remote direct memory access over converged Ethernet)网络进行性能对比测试。测试结果证明,GSE相较RoCE网络显著改善了任务完成时间(job completion time,JCT)。

随机丢包的无迹卡尔曼滤波估计以及性能分析

在工程应用中,无线网络控制系统多为非线性系统。由于长距离传输和通信网络不可靠等原因,系统传感器的测量值可能在传输过程中丢失,影响精度估计以及系统性能。文中研究一类受相关噪声和传感器测量值丢失影响的非线性离散随机系统的无迹卡尔曼滤波问题。通过引入一个服从伯努利分布且条件概率已知的随机变量来描述随机发生的传感器测量值丢失现象。文中提出了一种对数据进行补偿的算法,并使用标准数值软件对所得结果进行验证。结果表明,经过算法补偿后的滤波能够较好地估计系统,可以减少传感器测量值丢失对滤波器性能的影响,增加估计的准确性。

无线接入网络的时延优化算法

针对无线接入网络,提出一种轻量级时延优化算法——跨层反压拥塞控制算法。该算法是一种不依赖流量源端和用户终端设备,可独立部署在无线网络设备中的算法。该算法依据队列长度,空口发送速率等信息,动态调整TCP确认报文(TCP ACK)中的接收窗口字段,在降低业务端到端时延的同时,降低无线网络设备总缓存,保障无线接入设备(AP)的总吞吐能力(吞吐损耗<5%)。对比传统的Cubic拥塞控制算法,在AP为拥塞点的场景下,可降低无线接入网络时延30%—40%;同时降低AP设备40%的缓存,降低丢包风险。

基于流量延时调度的无线传感网数据传输拥塞控制方法

无线传感网络在数据传输时出现流量控制困难和节点拥塞的情况,为此提出一种新的基于流量延时调度的传输拥塞控制方法。引入流量延时调度,确定数据流量,滤波处理数据流量,设置延时阈值,通过流量与延时阈值的对比,判断是否需要重新传输数据,完成数据传输控制机制设计。利用数据生成树获取网络有效数据包,以此计算信道可以传输数据包的概率临界值,构建数据传输拥堵控制模型,实现无线传感网数据传输拥塞控制。通过仿真分析得知,所提方法拥堵控制的能量消耗仅为149 J,数据传输速率提升到80 Mbit/s以上,数据完整度在99.0%以上,所提方法有效提高了数据传输速率和完整度,降低了能耗消耗,可以有效控制数据传输拥塞,具备了可行性。

无线通信网络随机接入信道拥塞联合控制研究

为解决信道拥塞期间频繁发生的数据丢包问题,针对无线通信网络随机接入信道拥塞联合控制方法展开研究。根据拥塞现象的产生原因,制定拥塞分类标准,并针对随机接入信道的拥塞特征展开分析。根据无线通信网络拓扑结构的连接方式,判断信道组织当前的拥塞状态,利用联合控制参数实现拥塞控制。对比实验结果表明,该方法可将丢包率控制在15%以下,对于解决信道拥塞期间频繁发生的数据丢包问题具有积极作用。