DS-MMAC:A Delay-Sensitive Multi-Channel MAC Protocol for Ambient Assistant Living Systems

In Ambient Assistant Living(AAL) systems, it is a fundamental problem to ensure prompt delivery of detected events, such as irregular heart rate or fall of elderly, to a central processing device(e.g. gateway node). Most of recently proposed MAC protocols for low-power embedded sensing systems(e.g. wireless sensor networks) are designed with energy efficiency as the first goal, so they are not suitable for AAL systems. Although some multi-channel MAC protocols have been proposed to address the problem, most of those protocols ignore the cost of channel switching, which can have reverse effect on network performance, especially latency of data delivery. In this paper, we propose a Delay-Sensitive Multi-channel MAC protocol(DS-MMAC) for AAL systems, which can provide high packet delivery ratio and bound low latency for data delivered to the gateway node. The novelty of the protocol is that an efficient distributed time slot scheduling and channel assignment algorithm is combined with the process of route establishment, which takes the channel switching cost into account and reduces endto-end delay to meet the required delay bound of each data flow. The performance of the proposed protocol is evaluated through extensive simulations. Results show that DS-MMAC can bound low latency for delivering detected events in AAL system to the gateway, while providing high delivery reliability and low energy consumption.

A new multi-channel MAC protocol based on CDMA for ad hoc networks

This paper proposes a novel multichannel medium access control （MAC） protocol based on CDMA that improves network performance and reduces collision probability in wireless ad hoc networks. In the scheme, the code channel is divided into common channel, broadcast channel and several data channels. Simulation results show that the proposed protocol can achieve significantly better performance than the IEEE 802.11 standard.

一种移动感知的太赫兹无线局域网定向MAC协议

现有太赫兹无线局域网定向MAC(Medium Access Control)协议中,节点移动情况下PNC(PicoNet)发送beacon帧时存在部分控制字段浪费、CTAP(Channel Time Allocation Period)中PNC与DEV(Device)进行波束赋形开销偏大等问题。为此,提出了一种移动感知的太赫兹无线局域网定向MAC(Mobility-aware Directional MAC,MA-MAC)协议。该协议采用基于卡尔曼算法的节点扇区预测机制对移动节点的扇区范围进行迭代预测,采用基于DEV扇区预测的beacon帧内容填充机制对beacon帧中时隙分配字段进行填充,采用基于节点扇区预测的快速波束赋形机制使得PNC与DEV之间波束赋形操作简化。通过仿真验证,与基于IEEE 802.15.3c的太赫兹无线局域网定向MAC协议和现有协议进行对比,MA-MAC协议下网络吞吐量得到了提升,网络平均时延、网络整体控制开销得到了改善。

高效低时延分级多PAN太赫兹无线网络MAC层优化协议

针对现有分级多PAN太赫兹无线网络MAC(Medium Access Control)协议中存在的子网形成方案不合理以及私有CTA(Channel Time Allocation)与子网内实际负载不匹配等问题,提出了一种高效低时延的MAC层优化协议.该协议采用基于泛听的按需形成子网机制避免了子网分布不均匀以及因子网形成后没有节点加入而造成的私有CTA资源浪费的问题.在子网形成后,子微微网协调器(Piconet Coordinator,PNC)根据子网内实际负载情况自适应选择私有CTA时隙资源优化机制,让有数据传输需求的节点及时将数据发出.仿真结果表明,所提出的方案能有效地降低数据帧平均接入时延,提高吞吐量以及数据帧的传输成功率.

无线和电力线混合通信的MAC层接入算法设计和性能分析

电力线和无线混合通信可以优势互补提升电力物联网室内覆盖的综合性能。针对无线接入和电力线中继的混合通信场景,文章提出一种适用于两跳混合中继的通用MAC层算法。综合考虑物理层信道参数和MAC层的载波侦听多路访问(carrier sense multiple access,CSMA)退避流程,建立了该MAC层算法的跨层性能分析模型,推导了两跳传输系统归一化吞吐量以及系统时延等性能;最后仿真验证了算法有效性和模型准确性,分析了物理层和MAC层关键参数影响系统性能的机理。与Basic-RTS/CTS算法相比,所提算法可有效提升系统吞吐量和时延性能。

认知传感网中基于Transformer网络的MAC协议识别方法

媒体接入控制(Media Access Control,MAC)识别有助于优化认知无线电系统的频谱管理并提高通信质量。已有的基于深度学习的MAC协议识别方法仍存在复杂信道环境的适应性不足、长期依赖关系捕捉能力有限的问题。因此,提出基于Transformer网络的MAC协议识别方法,利用自注意力机制有效捕捉长距离依赖,通过多头注意力机制同时关注输入序列中不同部分的相关性,提升对信号特征和行为的理解。针对认知传感网的特定需求,对传统的Transformer模型结构进行了优化,包括调整模型的深度和宽度以适应信号数据的特性。自注意力机制不仅增强了模型对时间序列数据的处理能力,还通过位置编码保留序列中的位置信息,结合前馈神经网络增强模型的非线性表达能力,并通过层归一化和残差连接机制提高模型的稳定性和训练效率。实验结果表明,所提方法在复杂无线通信环境中具有显著的性能优势,在识别4种主要MAC协议时展现出超过95%的高准确率。

以太网MAC控制器GMII和RGMII接口转换IP设计

阐述RGMII接口是简化的GMII接口,解决GMII接口信号线过多造成的布线复杂和功耗大的问题。首先研究IEEE802.3千兆以太网MAC控制器的GMII接口协议和RGMII接口规范,分析在千兆以太网MAC控制器中两种接口转换的实现方案,包括RGMII正常和延迟模式的实现方案。用Verilog HDL完成代码实现,通过NC-SIM仿真和Quartus-II实现后下载到FPGA板验证,表明功能正确。最后将实现的RGMII应用到某以太网交换芯片。在交换芯片的功能板上两PC机通过RGMII接口和Marvell 88E1145等器件实现数据正确传输。通过这些流程,形成标准接口转换IP,可直接应用于其他产品。

基于FPGA的面向高负载业务的柔性信道预约MAC的设计与实现

针对定向自组织网络中高负载业务的通信需求,提出并实现了一种基于柔性信道预约的MAC协议,可以准确且不受干扰地使用或释放信道资源,保证网络吞吐量和时延要求。该协议主要引入了柔性信道预约机制、自适应MCS调整和自适应帧聚合等功能。整个协议在FPGA上进行设计和实现,并在Xilinx ZYNQ7010开发板上对整机节点业务传输功能进行验证。

基于MEC服务器优先服务的路侧单元MAC层调度策略

针对多接入边缘计算(MEC)服务器高可靠、低时延和大数据量的数据传输要求,基于无冲突接入、优先级架构和弹性服务技术,提出一种适用于车辆边缘计算场景下的媒体访问控制(MAC)调度策略。所提策略由车联网(IoV)路侧单元(RSU)集中协调信道接入权,优先确保车载网络中车载通信单元(OBU)与MEC服务器之间的链路传输质量,以及时传输车辆到网络(V2N)业务数据;同时,对本地OBU之间的业务采取弹性服务方式,增强密集车辆接入时应急消息传输的可靠性。首先,构建调度策略的排队分析模型;其次,根据各时刻系统状态变量的无后效性特点建立嵌入式马尔可夫链,并通过概率母函数的分析方法对系统进行理论分析,得到MEC服务器通信单元和OBU的平均排队队长、平均等待时延和RSU查询周期等关键指标的精确解析表达式。计算机仿真实验结果表明,统计分析结果与理论计算结果一致,所提调度策略在高负载情况下能够提高IoV的稳定性和灵活性。

Jamming Assisted Covert Wireless Communication in Multi-Channel Systems

This paper investigates the jammerassisted multi-channel covert wireless communication(CWC)by exploiting the randomness of sub-channel selection to confuse the warden.In particular,we propose two sub-channel selection transmission schemes,named random sub-channel selection(RSS)scheme and maximum sub-channel selection(MSS)scheme,to enhance communication covertness.For each proposed scheme,we first derive closed-form expressions of the transmission outage probability(TOP),the average effective rate,and the minimum average detection error probability(DEP).Then,the average effective covert rate(ECR)is maximized by jointly optimizing the transmit power at the transmitter and the number of sub-channels.Numerical results show that there is an optimal value of the number of sub-channels that maximizes the average ECR.We also find that to achieve the maximum average ECR,a larger number of subchannels are needed facing a stricter covertness constraint.

基于深度强化学习的水声网络公平跨层MAC协议

针对水声通信异构网络中信道分配不公和节点能量受限的问题,基于深度强化学习方法,提出跨层联合优化公平信道接入和功率控制的媒介访问控制(POCL-MAC)协议。根据反馈ACK包获知时延状态下的信道冲突结果和接收机处信噪比,基于深度强化学习的状态、动作和奖励序列自主学习,调整认知用户的接入时隙和发射功率;采用公平函数实现异构网络中认知用户和主用户吞吐量性能的比例公平。设计了一个联合状态序列和独立式奖励函数,在不增加神经网络复杂度的前提下,提高跨层联合优化的子动作决策准确度。仿真结果表明,相比于传统DRL算法,所提算法实现了接近于最优公平性吞吐量性能,同时具有更好的能量利用效率。

基于IR-UWB的高吞吐量、低延时MAC协议硬件设计

针对IEEE 802.15.4高速数据传输的应用场景,提出一种具有高吞吐量和低延时特性的定制化MAC协议。基于HRP UWB PHY对数据传输模型和吞吐量深入分析,并结合MAC协议的冲突避免载波侦听多路访问(Carrier Sense Multiple Access with Collision Avoid,CSMA-CA)和保障时隙(Guaranteed Timeslot,GTS)实时传输的特性,设计了该机制有效的管理流程。最后在Vivado中使用Verilog HDL对MAC控制器进行硬件设计和验证。仿真结果表明,与经典IEEE 802.15.4 MAC协议相比,该MAC控制器的吞吐量提高了26%,同时数据传输时延降低了17%。

A novel multi-channel porous structure facilitating mass transport towards highly efficient alkaline water electrolysis

An advantageous porous architecture of electrodes is pivotal in significantly enhancing alkaline water electrolysis(AWE)efficiency by optimizing the mass transport mechanisms.This effect becomes even more pronounced when aiming to achieve elevated current densities.Herein,we employed a rapid and scalable laser texturing process to craft novel multi-channel porous electrodes.Particularly,the obtained electrodes exhibit the lowest Tafel slope of 79 mV dec^(-1)(HER)and 49 mV dec^(-1)(OER).As anticipated,the alkaline electrolyzer(AEL)cell incorporating multi-channel porous electrodes(NP-LT30)exhibited a remarkable improvement in cell efficiency,with voltage drops(from 2.28 to 1.97 V)exceeding 300 mV under 1 A cm^(-1),compared to conventional perforated Ni plate electrodes.This enhancement mainly stemmed from the employed multi-channel porous structure,facilitating mass transport and bubble dynamics through an innovative convection mode,surpassing the traditional convection mode.Furthermore,the NP-LT30-based AEL cell demonstrated exceptional durability for 300 h under 1.0 A cm^(-2).This study underscores the capability of the novel multi-channel porous electrodes to expedite mass transport in practical AWE applications.

无人机群自组网MAC协议综述

近年来,无人机群自组网(UAV Swarm Ad Hoc Network,UAVSNet)的单个UAV不断自主化与智能化,但UAV之间的协同通信仍存在挑战。媒体接入控制(Media Access Control,MAC)协议是其关键技术之一,并成为了新的研究热点。通过概述MAC协议的分类及设计要点,对竞争类MAC协议、非竞争类MAC协议以及混合类MAC协议接入机制、性能表现及不足进行详细综述并提出展望。为UAVSNet的MAC协议的研究和应用提供了理论支持。

Analysis of the Cicatricial Acceleration Method (MAC®) in Skin Repair in Wistar Rattus norvegicus with Induced Chemical Burns

Introduction: The cicatricial acceleration method (MAC®) promotes photobiological effects of an anti-inflammatory and healing nature. Its therapeutic radiation is emitted, producing photobiostimulant effects that result in rapid tissue repair and better tissue quality. The treatment of burns has always been a challenge, which involves both performing surgery and controlling and guiding scar regeneration, avoiding possible morbidities. Objective: To evaluate the effects of applying the MAC methodology with an AlGa (aluminum, gallium arsenide) laser on the time and quality of tissue repair in the skin of rats after induced chemical burns. Method: 22 adult male rats were subjected to a second-degree chemical burn on the back using 50% trichloroacetic acid. After the burns, the animals were randomly separated into 2 groups: control and experimental. The control group (G1) received placebo laser therapy and the laser group (G2) underwent laser irradiation with an energy density of 100 J/cm2. Histological analysis and macroscopic evaluation were carried out by means of the paper template method. Results: Group G1 showed (53%) of the necrosis area and group G2 showed (11%) necrosis area. Conclusion: The cicatricial acceleration method (MAC®) favored the repair of wounds caused by a 2nd-degree chemical burn, optimizing time and improving quality.

基于MAC准入控制与网络流量监控的哑终端入网管控系统设计

企业网络中大量哑终端设备的使用,给企业管理带来便利的同时,也带来较大安全隐患。通过分析主流准入控制方式的实现特点及不足,提出一种针对哑终端设备的MAC准入控制方式+网络流量监控相结合的准入控制方法,该方法能够利用2种认证方式的优点,弥补各认证方式自身的不足,使得针对哑终端设备的网络准入控制能够依托于接入交换机的MAC认证机制实现端口级别的管控。同时,根据哑终端设备网络业务流量相对固定的特点,采用网络流量监控的方式,为MAC准入控制方式提供持续性的、更细粒度的准入判决控制。

LSDR-ALOHA-Q:基于强化学习适用于大范围远距离的水下无线传感器网络MAC协议

随着对海洋开发需求的日益增长,水下无线传感器网络成为研究的热点。但由于水下环境信道可用带宽有限,传输速度和传播速度都慢,多普勒效应和多径效应严重等众多不利因素,导致水下网络性能低下。这主要是因为缺少在大范围远距离的水下网络中表现良好的媒体访问控制协议(MAC协议)。提出的LSDR-ALOHA-Q协议以ALOHA-Q协议为基础,该协议采用加入强化学习的方法,以提高信道利用率,同时结合强化学习使得该协议能够适应多变和复杂的水下环境。提出的LSDR-ALOHA-Q协议包括对时隙和帧结构的改造,使其更适合于大范围网络,通过优化时隙数,主动寻找空间复用的机会来增加信道利用率,同时通过提出一个新的退避算法来避免因为优化时隙数量而带来的Q-learning可能无法收敛的问题,即可能存在节点一直无法找到无冲突发送时间的问题。仿真表明当LSDR-ALOHA-Q协议被应用到大规模远距离的网络时可以显著提升信道利用率,同时降低冲突率和平均端到端时延。

基于空中平台通信系统的MAC层调度算法优化研究

随着应用场景的日益增多和复杂化,传统的MAC层调度算法面临多种挑战,如资源利用率低、时延大、不公平的资源分配等,这些问题迫切需要通过算法优化得到解决。围绕空中平台通信系统的MAC层调度算法优化,文章首先分析了系统的工作原理和架构,指出了现有MAC层调度算法面临的主要挑战和优化需求,接着提出了一种新的调度优化算法。该算法结合时间片轮转和多级队列调度的策略,旨在提高资源利用率并减少通信延迟,从而实现更公平的资源分配。最终,文章通过一系列技术测试和性能评估验证了所提算法在不同场景下的有效性和优越性,为空中平台通信系统的MAC层调度提供了一种新的优化方案。

Priority Based Energy Efficient MAC Protocol by Varying Data Ratefor Wireless Body Area Network

Wireless Body Area Network(WBAN)is a cutting-edge technology that is being used in healthcare applications to monitor critical events in the human body.WBAN is a collection of in-body and on-body sensors that monitor human physical parameters such as temperature,blood pressure,pulse rate,oxygen level,body motion,and so on.They sense the data and communicate it to the Body Area Network(BAN)Coordinator.The main challenge for the WBAN is energy consumption.These issues can be addressed by implementing an effective Medium Access Control(MAC)protocol that reduces energy consumption and increases network lifetime.The purpose of the study is to minimize the energy consumption and minimize the delay using IEEE 802.15.4 standard.In our proposed work,if any critical events have occurred the proposed work is to classify and prioritize the data.We gave priority to the highly critical data to get the Guarantee Tine Slots(GTS)in IEEE 802.15.4 standard superframe to achieve greater energy efficiency.The proposed MAC provides higher data rates for critical data based on the history and current condition and also provides the best reliable service to high critical data and critical data by predicting node similarity.As an outcome,we proposed a MAC protocol for Variable Data Rates(MVDR).When compared to existing MAC protocols,the MVDR performed very well with low energy intake,less interruption,and an enhanced packet-sharing ratio.

基于MAC算法的移动通信基站调度系统优化研究

移动通信基站的调度系统对于优化网络性能至关重要,文中深入研究与优化了基于MAC算法的移动通信基站调度系统。首先,介绍了MAC协议的基本原理及其在移动通信中的应用,分析了目前常见的MAC算法及特点。其次,探讨了移动通信基站调度系统的优化需求,如需要提升系统资源利用率、用户体验和能源效率。在此基础上,提出了基于QoS的资源分配、基于机器学习的动态调度算法以及基于协作通信的优化方案。最后,通过实验设计与结果分析,验证了优化策略的有效性与可行性。