A Nodal Electricity Market Design Based on Regulated Access to Transmission Network

Accomodation of power system constraints with the market mechanism is encountered as a major challenge along the way toward implementation of different electricity market designs. Allocation of fixe or flow-dependent inter-zone trading capacities by the PX （power exchange） can not be accepted unreservedly. The paper is meant to show that a nodal electricity market design that is based on bids for local energy and a regulated transmission access including allocation of ＂entry-exit＂ transmission capacity would be the desired solution. The market players could easily optimize their portfolio while the TSOs （transmission system operators） are requested to mobilize the network＇s in-built flexibility to increase the cross zonal capacity. In the proposed market design, the PX＇s allocation of trading capacity is clearly separate from the TSO＇s management of the power system operational constraint5. Clear operator roles would enlarge access to electricity market as well as market integration of variable RESs （renewable energy sources） that are critically dependent on short notice access to regionat markets,

Challenges for beyond 5G:ultra-densification of radio access network

Ultra-densification of radio access network(RAN)is a key to efficiently support the exponentially growing mobile data traffic in 5 G era.Furthermore,extremely high frequency band like mm Wave band was utilized to solve the bandwidth shortage problem.However,untra-dense reusing the same radio resource produced severe interference.And the mm Wave link was very harsh due to frequent blockage by obstacles.Therefore a new RAN architecture needed to be introduced to realize ultra-reliable communications in such a severe radio propagation environment.An architecture of distributed MIMO based RAN was presented.Then,enhanced interference coordination(e IC)was described.Finally,the effectiveness of distributed MIMO based RAN with e IC by computer simulation was showed.

HetNets Under Decoupled Uplink and Downlink Access with UE Random Discontinuous Transmission: Local Delay and Energy Efficiency

Due to the limited uplink capability in heterogeneousnetworks (HetNets), the decoupled uplinkand downlink access (DUDA) mode has recently beenproposed to improve the uplink performance. In thispaper, the random discontinuous transmission (DTX)at user equipment (UE) is adopted to reduce the interferencecorrelation across different time slots. By utilizingstochastic geometry, we analytically derive themean local delay and energy efficiency (EE) of an uplinkHetNet with UE random DTX scheme under theDUDA mode. These expressions are further approximatedas closed forms under reasonable assumptions.Our results reveal that under the DUDA mode, there isan optimal EE with respect to mute probability underthe finite local delay constraint. In addition, with thesame finite mean local delay as under the coupled uplinkand downlink access (CUDA) mode, the HetNetsunder the DUDA mode can achieve a higher EE witha lower mute probability.

Minimizing the Impact of Long Propagation Delay on Multiple Access for Wireless Networks

A multiple access protocol is proposed to greatly improve multiple access performance of wireless networks with long propagation delay. All the nodes with packets to send can make rapid successful reservation in access reservation mini-slots, which is adaptively adjusted according to current traffic load and idle channel resources. A Central Control Node (CCN) coordinates channel reservation and allocates on-demand channel resources to the successfully accessed nodes on two channels. Each node can employ only one handshake to accomplish each communication session, and transmit one or multiple data packets piggybacked with acknowledgment (ACK) information to one or multiple destination nodes in each frame until the end of their communication sessions, which greatly minimizes the impact of long propagation delay caused by handshakes and improves channel efficiency. Simulation results show that the proposed protocol obviously outperforms the Centralized Scheduling-based Medium Access Control (CSMAC) protocol, especially in the presence of long propagation delay.

Deep Unfolding for Cooperative Rate Splitting Multiple Access in Hybrid Satellite Terrestrial Networks

Rate splitting multiple access(RSMA)has shown great potentials for the next generation communication systems.In this work,we consider a two-user system in hybrid satellite terrestrial network(HSTN)where one of them is heavily shadowed and the other uses cooperative RSMA to improve the transmission quality.The non-convex weighted sum rate(WSR)problem formulated based on this model is usually optimized by computational burdened weighted minimum mean square error(WMMSE)algorithm.We propose to apply deep unfolding to solve the optimization problem,which maps WMMSE iterations into a layer-wise network and could achieve better performance within limited iterations.We also incorporate momentum accelerated projection gradient descent(PGD)algorithm to circumvent the complicated operations in WMMSE that are not amenable for unfolding and mapping.The momentum and step size in deep unfolding network are selected as trainable parameters for training.As shown in the simulation results,deep unfolding scheme has WSR and convergence speed advantages over original WMMSE algorithm.

Performance Analysis in Cloud Radio Access Networks:User-Centralized Coordination Approach

The cloud radio access network(C-RAN) has recently been proposed as an important component of the next generation wireless networks providing opportunities for improving both spectral and energy effi ciencies. The performance of this network structure is however constrained by severe inter-cell interference due to the limited capacity of fronthaul between the radio remote heads(RRH) and the base band unit(BBU) pool. To achieve performance improvement taking full advantage of centralized processing capabilities of C-RANs,a set of RRHs can jointly transmit data to the same UE for improved spectral effi ciency. In this paper,a user centralized joint coordinated transmission(UC-JCT) scheme is put forth to investigate the downlink performance of C-RANs. The most important benefit the proposed strategy is the ability to translate what would have been the most dominant interfering sources to usable signal leading to a signifi cantly improved performance. Stochastic geometry is utilized to model the randomness of RRH location and provides a reliable performance analysis. We derive an analytical expression for the closed integral form of the coverage probability of a typical UE. Simulation results confirm the accuracy of our analysis and demonstrate that significant performance gain can be achieved from the proposed coordination schemes.

Effective and Extensive Virtual Private Network

A Virtual Private Network (VPN) allows the provisioning of private network services for an organization over a public network such as the Internet. In other words a VPN can transform the characteristics of a public which may be non-secure network into those of a private secure network through using encrypted tunnels. This work customized a standard VPN to a newly one called EEVPN (Effective Extensive VPN). It transmits a small data size in through a web based system in a reasonable time without affecting the security level. The proposed EEVPN is more effective where it takes small data transmission time with achieving high level of security. Also, the proposed EEVPN is more extensive because it is not built for a specific environment.

Access VPN浅析及其PPTP实现

介绍了AccessVPN的工作原理、功能及实现的基本要求,对VPN常用的协议进行了分析、对比,并以应用比较广泛的PPTP协议为例,给出了软件实现虚拟专用网的具体配置方法。

An application-layer based centralized information access control for VPN

With the rapid development of Virtual Private Network (VPN), many companies and organizations use VPN to implement their private communication. Traditionally, VPN uses security protocols to protect the confidentiality of data, the message integrity and the endpoint authentication. One core technique of VPN is tunneling, by which clients can access the in- ternal servers traversing VPN. However, the tunneling technique also introduces a concealed security hole. It is possible that if one vicious user can establish tunneling by the VPN server, he can compromise the internal servers behind the VPN server. So this paper presents a novel Application-layer based Centralized Information Access Control (ACIAC) for VPN to solve this problem. To implement an efficient, flexible and multi-decision access control model, we present two key techniques to ACIAC—the centralized management mechanism and the stream-based access control. Firstly, we implement the information center and the constraints/events center for ACIAC. By the two centers, we can provide an abstract access control mechanism, and the material access control can be decided dynamically by the ACIAC’s constraint/event mechanism. Then we logically classify the VPN communication traffic into the access stream and the data stream so that we can tightly couple the features of VPN communication with the access control model. We also provide the design of our ACIAC prototype in this paper.

Remote Access Communications Security: Analysis of User Authentication Roles in Organizations

Remote access is a means of accessing resources outside one’s immediate physical location. This has made employee mobility more effective and productive for most organizations. Remote access can be achieved via various channels of remote communication, the most common being Virtual Private Networks (VPNs). The demand for remote access is on the rise, especially during the Covid-19 pandemic, and will continue to increase as most organizations are re-structuring to make telecommuting a permanent part of their mode of operation. Employee mobility, while presenting organizations with some advantages, comes with the associated risk of exposing corporate cyber assets to attackers. The remote user and the remote connectivity technology present some vulnerabilities which can be exploited by any threat agent to violate the confidentiality, integrity and availability (CIA) dimensions of these cyber assets. So, how are users and remote devices authenticated? To what extent is the established connection secured? With employee mobility on the rise, it is necessary to analyze the user authentication role since the mobile employee is not under the monitoring radar of the organization, and the environment from which the mobile employee connects may be vulnerable. In this study, an experiment was setup to ascertain the user authentication roles. The experiment showed the process of 2FA in user authentication and it proved to be an effective means of improving user authentication during remote access. This was depicted via the use of what the user has (mobile phone/soft-token) as a second factor in addition to what the user knows, i.e. password. This authentication method overcomes the security weaknesses inherent in single-factor user authentication via the use of password only. However, the results also showed that though 2FA user authentication ensures security, the remote devices could exhibit further vulnerabilities and pose serious risks to the organization. Thus, a varied implementation was recommended to further enhance the security of remote access communication with regards to the remote user authentication.

Routing Protocol in Underwater Wireless Acoustic Communication Using Non Orthogonal Multiple Access

The underwater wireless communication with the complexity of attenuation and low propagation speed makes resource constraints in networking sensor nodes and sink.Underwater Sensor Transmission with Attenuation Calculation using Non Orthogonal Multiple Access(UWSTAC-NOMA)protocol has been proposed.This protocol calculates channel gain along with attenuation in underwater channels and provides internetworking sensor for rate allocation minimizing interference.Successive Interference Cancellation has been used at the receiving sensor to decode the information sent.The network level performance of sensors and increasing the data rate improves the overall throughput.Simultaneously,connecting several sensors to sink based on its depth region of deployment has been achieved using Underwater Sensor Transmission with Attenuation Calculation using Non Orthogonal Multiple Access(UWSTAC-NOMA).The analytical background of attenuation never confuted the simulation results of the proposed protocol in NS2 simulator.Simulation results shows that the throughput,average bit error rate and residual energy of sink performance.

Recent Advances of Multi-Channel Transmission in Metro Access Networks

We discuss the concept of coarse wavelength-division multiplexing (CWDM) for metro networks. After reviewing the requirements on components such as lasers and fiber, we propose different architectures for a flexible upgrade of existing CWDM systems.

Design of Wireless Optical Access System using LED

This paper develops a prototype to demonstrate a full-duplex wireless visible light communication (VLC) system based on Universal Serial Bus (USB) port. Combing with a USB 2.0 port on one board, it can achieve up to 2 Mbps bit rates error free, which is mainly limited to the USB bridge circuit, between two computers for data transmission, such as text, audio and video. Hyper Terminal and self-written software are used to allow setting the transmission data rate, control bits, check bits and achieve real-time transmission between any two mobile devices with a USB port. The work is based on the research of VLC local access network. This paper also shows the experimental results and the relationship between system transmission eye diagram and bit rate.

基于RTD1296的私有存储设备的设计

为满足私有存储设备传输安全、传输数据高效、节省电能的需求,设计一种以RTD1296为控制核心的千兆私有存储设备。该设备搭载Ubuntu系统和SFTP服务器,确保数据传输安全;采用千兆以太网和千兆无线网卡无缝连接互联网,确保数据高效传输;使用ZeroTier异地组网技术实现内网穿透;使用MQTT技术实现设备远程开关机,达到节省电能和保护磁盘数据安全的效果;使用AIRKISS+ESPTOUCH技术实现智能手机配网;具有蓝牙连接一键唤醒设备,提醒用户备份,易用高效。实验结果表明,所设计的私有存储设备能够保证数据传输安全,相比于RTD1195存储设备,该设备的下载速度快3倍,上传速度快7倍,整机节能高达50%,可实现安全、高效、节能、易用的目标。

面向集成的VPN解决方案

针对传统方式构建的VPN不支持承载多种数据类型、承载数据缺乏安全性、标签边缘设备负载过重等问题,提出了集成的VPN解决方案。该方案设计包含GRE VPN的建立、IPSEC VPN的建立、网络设备虚拟化、MPLS VPN的建立、私网数据的识别与隔离5个关键步骤,实现了各VPN技术数据的嵌套与各VPN技术的相互融合,融合后的VPN既支持承载多种数据类型,又支持数据交互的安全,且能实现私网数据访问控制与地址复用,还能实现数据的负载分担。为验证方案的可行性,对方案建立的隧道、网络资源池、标签转发路径等方面进行了测试与验证,达到了预期设定的目标。为凸显方案的优势,与传统方式在背板带宽、端口速率等方面进行了对比分析。分析结果表明,该方案的背板带宽与端口速率随着资源池中设备数的增加而增长,其数据传输能力相比传统方式成倍增长,且在数据的负载分担、数据安全、可管理性与可维护性等方面优于传统方案,为构建实用、可靠、安全的VPN提供了思路。

校企共建多网融合下的“5G+智慧校园”研究

以5G技术为信息化新基建载体,设计“5G+智慧校园”的实施框架。从运用5G技术全面赋能高校智慧校园实现共建、共融、共享为切入点,剖析智慧校园视域下5G智慧应用的现实需求,分析“5G+智慧应用”的作用与研究意义。结合某高校 “5G+智慧应用”多类应用场景实践,从部署模式、分流及认证、信息安全保障三个方面探究校园5G专网模式下基建新生态关键技术方案,为构筑泛在接入、多网融合、部署灵活、安全可控的5G创新应用提供支撑。

一种基于虚拟专用网的网络安全解决方法

随着信息社会化的到来,网络安全形势日益严峻。组织单位内的个人身份信息、生物识别信息、单位财务信息、商业机密等敏感信息一旦泄露,可能会导致组织单位遭受重大财产损失。本文提供一种组织内部敏感信息安全访问的解决方案,其思路是将网络划分成三个区域,将组织单位服务器及敏感信息置于授权的虚拟专用网络中,其他区域均应通过严格的身份认证和授权方可访问授权区域,同时通过高强度的加密技术和安全传输通道实现信息的安全传输。

5G技术在气象专网备份链路中的创新应用与性能分析

在气象数据的传输过程中,通常依赖内网有线宽带进行。然而,面对设备故障、人为失误或自然灾害等不可预见因素,有线专网可能会出现中断,导致数据传输受阻。这种情况下,急需一种可靠的应急通信手段来替代内网有线通信,以确保数据的连续性和实时性。此外,随着气象高质量发展需要,如何实现移动应急观测数据、水文数据、交通数据等外部数据与气象内部数据的交互,成为了一个亟待解决的问题。为了应对这些问题,文中研究了5G技术在气象专网备份链路中的创新应用。通过性能分析和实际测试,验证了5G技术在气象数据传输中的可行性及显著优势。研究结果表明,5G技术以其高带宽和低时延的特性,能有效增强气象专网的备份能力和扩展能力。这不仅保证了气象数据通信的连续性和稳定性,还提升了气象服务的可靠性和准确性。

基站无线回传技术研究

有些场景光纤传输部署困难、成本高、周期长,需研究使用无线传输将基站和核心网连通。首先介绍了无线回传的应用场景,详细论述和对比了实现无线回传的可行技术方案,分析了无线回传中头开销、MTU和时延的影响,为特定场景使用无线回传方案提供了参考。

考虑输变电设备温度约束的配电网空调负荷实时聚合调控

为解决迎峰度夏期间因输变电设备温度限制而引发的紧急切负荷问题,充分考虑新能源出力和负荷的随机波动,提出考虑输变电设备温度约束的配电网多冷水机组暖通空调负荷实时聚合调控方法。建立考虑多冷水机组负荷分配策略的暖通空调线性能耗模型,设计基于聚合虚拟储能模型的统一信号调控方法,并根据输变电设备的物理结构,构建输变电设备的线性化温度约束模型;计及交流潮流、电压和输变电设备温度等运行约束,以系统经济性最优为目标建立配电网暖通空调负荷调控模型;为应对配电网的强随机性,提出基于近似动态规划的配电网暖通空调负荷实时调控策略,并采用与暖通空调虚拟储能荷电状态相关的分段线性函数对值函数进行近似,解决传统动态规划方法面临的“维数爆炸”问题。算例分析结果表明,所提方法可满足实时调控的快速性和准确性要求,并有效提升配电网供电的可靠性和经济性。