Uniquely Decomposable Constellation Group-Based Sparse Vector Coding for Short Packet Communications

Sparse vector coding(SVC)is emerging as a potential technology for short packet communications.To further improve the block error rate(BLER)performance,a uniquely decomposable constellation group-based SVC(UDCG-SVC)is proposed in this article.Additionally,in order to achieve an optimal BLER performance of UDCG-SVC,a problem to optimize the coding gain of UDCG-based superimposed constellation is formulated.Given the energy of rotation constellations in UDCG,this problem is solved by converting it into finding the maximized minimum Euclidean distance of the superimposed constellation.Simulation results demonstrate the validness of our derivation.We also find that the proposed UDCGSVC has better BLER performance compared to other SVC schemes,especially under the high order modulation scenarios.

Decision Tree Based Key Management for Secure Group Communication

Group communication is widely used by most of the emerging network applications like telecommunication,video conferencing,simulation applications,distributed and other interactive systems.Secured group communication plays a vital role in case of providing the integrity,authenticity,confidentiality,and availability of the message delivered among the group members with respect to communicate securely between the inter group or else within the group.In secure group communications,the time cost associated with the key updating in the proceedings of the member join and departure is an important aspect of the quality of service,particularly in the large groups with highly active membership.Hence,the paper is aimed to achieve better cost and time efficiency through an improved DC multicast routing protocol which is used to expose the path between the nodes participating in the group communication.During this process,each node constructs an adaptive Ptolemy decision tree for the purpose of generating the contributory key.Each of the node is comprised of three keys which will be exchanged between the nodes for considering the group key for the purpose of secure and cost-efficient group communication.The rekeying process is performed when a member leaves or adds into the group.The performance metrics of novel approach is measured depending on the important factors such as computational and communicational cost,rekeying process and formation of the group.It is concluded from the study that the technique has reduced the computational and communicational cost of the secure group communication when compared to the other existing methods.

Integrating IPsec within OpenFlow Architecture for Secure Group Communication

Network security protocols such as IPsec have been used for many years to ensure robust end-to-end communication and are important in the context of SDN. Despite the widespread installation of IPsec to date, per-packet protection offered by the protocol is not very compatible with OpenFlow and tlow-like behavior. OpenFlow architecture cannot aggregate IPsee-ESP flows in transport mode or tunnel mode because layer-3 information is encrypted and therefore unreadable. In this paper, we propose using the Security Parameter Index （SPI） of IPsec within the OpenFlow architecture to identify and direct IPsec flows. This enables IPsec to conform to the packet-based behavior of OpenFlow architecture. In addition, by distinguishing between IPsec flows, the architecture is particularly suited to secure group communication.

A Secure Key Management Scheme for Heterogeneous Secure Vehicular Communication Systems

Intelligent transportation system （ITS） is proposed as the most effective way to improve road safety and traffic efficiency. However, the future of ITS for large scale transportation infrastructures deployment highly depends on the security level of vehicular communication systems （VCS）. Security applications in VCS are fulfilled through secured group broadcast. Therefore, secure key management schemes are considered as a critical research topic for network security. In this paper, we propose a framework for providing secure key management within heterogeneous network. The seeurity managers （SMs） play a key role in the framework by retrieving the vehicle departnre infi^rmation, encapsulating block to transport keys and then executing rekeying to vehicles within the same security domain. The first part of this framework is a novel Group Key Management （GKM） scheme basing on leaving probability （LP） of vehicles to depart current VCS region. Vehicle＇s LP factor is introduced into GKM scheme to achieve a more effieient rekeying scheme and less rekeying costs. The second component of the framework using the blockchain concept to simplify the distributed key management in heterogeneous VCS domains. Extensive simulations and analysis are provided to show the effectiveness and effieiency of the proposed framework： Our GKM results demonstrate that probability-based BR reduees rekeying eost compared to the benchmark scheme, while the blockchain deereases the time eost of key transmission over heterogeneous net-works.

Group Activities in Task-based Communicative Classroom

In a task-based communicative classroom, group activities are effective ways to devdop students' 4 basic language skills. However, not all group activities can reach the expected results. English teachers should pay attention to some aspects in organizing a classroom group activity.

Improvisation of Node Mobility Using Cluster Routing-based Group Adaptive in MANET

In today's Internet routing infrastructure,designers have addressed scal-ing concerns in routing constrained multiobjective optimization problems examining latency and mobility concerns as a secondary constrain.In tactical Mobile Ad-hoc Network(MANET),hubs can function based on the work plan in various social affairs and the internally connected hubs are almost having the related moving standards where the topology between one and the other are tightly coupled in steady support by considering the touchstone of hubs such as a self-sorted out,self-mending and self-administration.Clustering in the routing process is one of the key aspects to increase MANET performance by coordinat-ing the pathways using multiple criteria and analytics.We present a Group Adaptive Hybrid Routing Algorithm(GAHRA)for gathering portability,which pursues table-driven directing methodology in stable accumulations and on-request steering strategy for versatile situations.Based on this aspect,the research demonstrates an adjustable framework for commuting between the table-driven approach and the on-request approach,with the objectives of enhancing the out-put of MANET routing computation in each hub.Simulation analysis and replication results reveal that the proposed method is promising than a single well-known existing routing approach and is well-suited for sensitive MANET applications.

A Discrepancy between An Advocacy of Group Work and the Reality of Its Poor Implementation ELT Classrooms of Junior High Schools in China's Mainland

The paper investigates how group work was implemented in English teaching classrooms in a junior high school of China's Mainland as a case study. The research data was collected by classroom observations, a survey of the students and interviews with the classroom teachers. The research finds a mismatch between an advocacy of group work and the reality of its poor implementation. It has implications on English curriculum innovation and the advocacy of group work in ELT classrooms in China's Mainland.

Towards Interaction,Communication and Integration of Ethnic Groups with Commonality:A Comparison of Inner Mongolia,Guangxi and Ningxia Autonomous Region

One crucial measure of strengthening and advancing the Party's work on ethnic affairs in the new era is to promote interaction,communication and integration of various ethnic groups,so as to enhance commonality.Entering the new era,Inner Mongolia,Guangxi and Ningxia have achieved remarkable results in encouraging interaction,communication and integration of various ethnic groups.By comparatively analyzing successes of the three autonomous regions through the perspective of promoting commonality,this article summarizes the following strategic revelations:1)we should comprehensively implement the Party's ethnic policies and ensure theactual implementation of mutual interaction,mutual communication and mutual integration of ethnic groups;2)we should proactively promote the substantial progress of the economy,so as to provide solid material foundation for mutual interaction,mutual communication and mutual integration of ethnic groups;3)we should facilitate activities that promote ethnic unity and progress,so that the promotion of interaction,communication and mutual integration of ethnic groups can be seen,be felt and gain actual outcomes;4)we should take measures that suit to local conditions and explore all-round embedding mechanisms in order to foster the ethos for mutual interaction,mutual communication and mutual integration of ethnic groups;5)we should make every effort to forge a strong sense of community for the Chinese nation and orient precisely to the cause of encouraging mutual interaction,mutual communication and mutual integration of ethnic groups.

Reliable Content Distribution in P2P Networks Based on Peer Groups

Peer-to-Peer (P2P) networks are highly dynamic systems which are very popular for content distribution in the Internet. A single peer remains in the system for an unpredictable amount of time, and the rate in which peers enter and leave the system, i.e. the churn, is often high. A user that is obtaining content from a selected peer is frequently informed that particular peer is not available anymore, and is asked to select another peer, or will have another peer assigned, often without enough checks to confirm that the content provided by the new peer presents the same quality of the previous peer. In this work we present a strategy based on group communication for transparent and robust content access in P2P networks. Instead of accessing a single peer for obtaining the desired content, a user request is received and processed by a group of peers. This group of peers, called PCG (Peer Content Group) provides reliable content access in sense that even as members of the group crash or leave the system, users continue to receive the content if at least one group member remains fault-free. Each PCG member is capable of independently serving the request. A PCG is transparent to the user, as the group interface is identical to the interface provided by a single peer. A group member is elected to serve each request. A fault monitoring component allows the detection of member crashes. If the peer is serving request crashes, another group member is elected to continue providing the service. The PCG and a P2P file sharing applications were implemented in the JXTA platform. Evaluation results are presented showing the latency of group operations and system components.

Energy-Efficient MTC Data Offloading in Wireless Networks Based on K-Means Grouping Technique

Machine-type communication (MTC) devices provide a broad range of data collection especially on the massive data generated environments such as urban, industrials and event-enabled areas. In dense deployments, the data collected at the closest locations between the MTC devices are spatially correlated. In this paper, we propose a k-means grouping technique to combine all MTC devices based on spatially correlated. The MTC devices collect the data on the event-based area and then transmit to the centralized aggregator for processing and computing. With the limitation of computational resources at the centralized aggregator, some grouped MTC devices data offloaded to the nearby base station collocated with the mobile edge-computing server. As a sensing capability adopted on MTC devices, we use a power exponential function model to compute a correlation coefficient existing between the MTC devices. Based on this framework, we compare the energy consumption when all data processed locally at centralized aggregator or offloaded at mobile edge computing server with optimal solution obtained by the brute force method. Then, the simulation results revealed that the proposed k-means grouping technique reduce the energy consumption at centralized aggregator while satisfying the required completion time.

The Assessment of Interpersonal Attraction and Group Identification in Virtual Group Network

This study investigates the measurement of social identification, interpersonal attraction, and cohesiveness in virtual groups. Different theoretical claims about relationships in computer-mediated groups rely on measurement strategies that are shown to reflect dramatically inconsistent semantic and administration features. A review of conceptual approaches and definitions for these constructs is presented. Data were collected from groups working asynchronously via the Internet under different geographic distributions, whose members completed a variety of measures related to these constructs. Analyses generated three likely dimensions of attraction. The research highlights the need for greater specificity in reports of the actual measures used in group research, and additional conceptual concerns regarding the contested relationships among these constructs.

Group Work in College English Teaching

In order to realize the communicative function of English and reduce the disadvantages of large-class teaching,group work can be adopted to achieve the goal to some extent with its practical significance.This paper aims to illustrate the advantages of group work and some reflections on the real application of group work activities in teaching.

Make WeChat Group Clean and Righteous Through Rectifying and Correcting

WeChat, obviously a new pet of people, becomes a useful tool of class management. WeChat group serves as an platform of delivering messages for teachers in time and assistant teaching, as well as a communication forum between student's parents and the teachers.

Improving Group Member Participation of 4th Year Section A Civil Engineering extension Students in integrated Project Work at Debre Markos University

Group work is a form of voluntary association of members benefiting from cooperative learning,which enhances the total output of the activity.Therefore,group discussion is a way for active participants to explore new ideas.Based on the previously observed practices in 4th year civil engineering students at Debre Markos University,the group member participations was not pleasing.The objective of this study was to identify the core causes of low participation of group members in their project work and to take actions for improving group member participation.The data collection method used questionnaires and interviews and was analyzed using Microsoft Excels.Action research done in civil engineering 4th year Extension courses focused on continuous advising and instruction.These practices have achieved a good understanding of how to increase active participation in their group work activities.Therefore,a main conclusion of this project is that an active learning method helps the students to share skill,knowledge and attitude to each other.

Matching theory based user-grouping for indoor non-orthogonal multiple access visible light communication heterogeneous networks

This Letter proposes a model of indoor visible light communication(VLC)heterogeneous networks entirely based on LEDs with different specifications and applies non-orthogonal multiple access(NOMA)to it because of the narrow modulation bandwidth of LEDs.Moreover,a user-grouping scheme that is based on matching theory is proposed to improve the network achievable sum rate.Simulation results indicate that when each NOMA cluster contains 6 users,the proposed scheme has a 49.54%sum-rate enhancement compared with the traditional user-grouping scheme.As the number of users in each NOMA cluster increases,the proposed scheme performs better at the cost of computational complexity.

Fault Tolerance and Recovery for Group Communication Services in Distributed Networks

Group communication services （GCSs） are becoming increasingly important as a wide field of promising applications has emerged to serve millions of users distributed across the world.However,it is challenging to make the service fault tolerance and scalable to fulfill the voluminous demand of users in a distributed network （DN）.While many reliable group communication protocols have been dedicated to addressing such a challenge so as to accommodate the changes in the network,they are often costly or require complicated strategies to handle the service interruptions caused by node departures or link failures,which hinders the service practicability.In this paper,we present two schemes to address the challenges.The first one is a location-aware replication scheme called NS,which makes replicas in a dispersed fashion that enables the services on nodes to gain immunity of failures with different patterns （e.g.,network partition and single point failure） while keeping replication overhead low.The second one is a novel failure recovery scheme that exploits the independence between service recovery and structure recovery in time domain to achieve quick failure recovery.Our simulation results indicate that the two proposed schemes outperform the existing schemes and simple alternative schemes in service success rate,recovery latency,and communication cost.

Lightweight Trusted Security for Emergency Communication Networks of Small Groups

Public communication infrastructures are susceptible to disasters. Thus, the Emergency Communication Networks(ECNs) of small groups are necessary to maintain real-time communication during disasters. Given that ECNs are self-built by users, the unavailability of infrastructures and the openness of wireless channels render them insecure. ECN security, however, is a rarely studied issue despite of its importance. Here, we propose a security scheme for the ECNs of small groups. Our scheme is based on the optimized Byzantine Generals’ Problem combined with the analysis of trusted security problems in ECNs. Applying the Byzantine Generals’ Problem to ECNs is a novel approach to realize two new functions, debugging and error correction, for ensuring system consistency and accuracy. Given the limitation of terminal devices, the lightweight fast ECDSA algorithm is introduced to guarantee the integrity and security of communication and the efficiency of the network. We implement a simulation to verify the feasibility of the algorithm after theoretical optimization.

慢性病高风险人群体重和血脂干预效果评价

目的 评价福田区慢性病高风险人群体重和血脂干预效果。 方法 2013年10—11月，通过简单随机抽样方法抽取12个社区，从中筛查出慢性病高风险人群1 923人，根据社区来源不同非随机分为干预组（ 1 338 人）和对照组（585人），干预组提供以健康生活方式指导为主的健康管理，对照组不主动采取任何形式干预活动。于2015年11-12月进行随访，采用倍差法评价体重和血脂干预效果。 结果 倍差法控制混杂因素后，干预2年后随访，干预组腰围、总胆固醇和低密度脂蛋白胆固醇分别下降1.929 cm、0.120 mmol/L、0.205 mmol/L，差异均有统计学意义 （ P 值均＜0.05）。 结论 以健康生活方式指导为主的健康管理，对慢性病高风险人群腰围、总胆固醇和低密度脂蛋白胆固醇等指标有一定程度的改善，可降低其慢性病的发病风险。

从族际交往看当代黔中地区屯堡人与周边少数民族的关系

费孝通先生曾指出"民族关系是指民族与民族之间的交往关系。"所以本文从族际交往这一视角来分析贵州省安顺地区"屯堡人"与周边少数民族的关系在当代的演变情况。通过研究我们发现:在长期的发展过程中,当代黔中地区屯堡人与周边少数民族的交往日渐频繁,民族关系日益融洽。

The Homomorphic Key Agreement

There are various challenges that are faced in group communication, so it is necessary to ensure session key. Key agreement is the fundamental cryptographic primitive for establishing a secure communication. It is a process of computing a shared secret contributed by two or more entities such that no single node can predetermine the resulting value. An authenticated key agreement is attained by combining the key agreement protocol with digital signatures. After a brief introduction to existing key agreement in group communication, Making use of the additive-multiplicative homomorphism in the integer ring defined by Sander and Tschudin: A new protocols, called the homomorphism key agreement, was designed, which can be self-contributory, robust, scalable and applicable in group communication.