Group Communication System Research Articles

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ЦЕНТРАЛИЗОВАННОГО И ДЕЦЕНТРАЛИЗОВАННОГО АЛГОРИТМОВ ДВИЖЕНИЯ СТРОЕМ БЛА МУЛЬТИКОПТЕРНОГО ТИПА

The development of robotics makes their group application relevant for solving varioustasks. The effectiveness of performing the tasks of detecting and determining the coordinates ofobjects by a group of robots significantly depends on the accuracy of maintaining a given formation.In this regard, the task of determining motion planning algorithms that ensure the greatestaccuracy of maintaining a given formation is of practical interest. This article is devoted to thestudy of the accuracy of maintaining the formation of a multicopter-type UAV group using a centralizedmotion planning algorithm and a decentralized algorithm. The centralized algorithm usesa master UAV, which transmits its coordinates to the slave UAVs. Based on the coordinates obtainedand the given framework of the formation, the guided UAVs plan their movement. In a decentralizedsystem, neighboring UAV groups transmit their coordinates to each other, on the basisof which the movement of a separate UAV is planned. The accuracy of the control system is investigateddepending on the errors of the navigation system and the frequency of updating data on theposition of the leading or neighboring UAVs. It is assumed that the group's UAVs determine their coordinates in discrete moments of time using an external navigation system. Centralized anddecentralized algorithms are worked out by the same motion control system. The algorithms areinvestigated in this article by numerical modeling methods. In the process of simulation, models ofkinematics, dynamics and actuators are taken into account, as well as models for the formation oferrors in the navigation system. It is shown that the de-centralized algorithm of group motionplanning provides higher accuracy compared to the centralized algorithm. However, the technicalimplementation of a decentralized algorithm is more complicated from the point of view of organizinga group communication system. In a centralized system, data transmission from the masterUAV to the slave should be implemented. In a decentralized system, it is required to implementnetwork communication.

Communication Strategies of Polish Exiles of the second half of the 19th Century (the example of Tara and Kurgan)

Diaspora studies penetrating into the Polish-Siberian theme since the late 1990s focused as a rule on the study of stable institutions, social organizations created by migrants for the preservation and development of ethnic community, and articulation of ethnic interests. However, such organizations among the Siberian Poles appeared only in the late XIX-early XX centuries. To understand the ethnic processes that took place among Polish migrants in the earlier period, the study of informal social ties of Polish migrants, various elements of group solidarity and communication systems becomes of paramount importance.
 The purpose of this study is to reconstruct, on the basis of office documentation and correspondence, the communication strategies of exiled participants in the revolts of the 1863-1864 on the example of two cities of Tobolsk province, namely, Kurgan and Tara.
 As a result of the study, we recorded the existence of a fraternity in Tara, covering most of the Poles who lived in the city. The self-organization of the exiles was facilitated by the presence of ready-made social structures – large traditional families and the system of communication between them that has developed at home. The emersion of the community in Kurgan was the result of the efforts of a group of exiled nobles who had a good education. In the conditions of a limited social status, and the absence of rich compatriots, the social value of this community turned out to be insufficient to become the center of attraction for Poles.

UMUcast: A Framework for Massive Small-Data Delivering in Industrial Internet of Things

As a key infrastructure of Industry 4.0, Industrial Internet-of-Things (IIoT) promises the opportunity to build powerful industrial environments by leveraging the growing ubiquity of wired and wireless communication technologies. Designing a data delivery scheme in the future IIoT networks is undoubtedly a challenging task, as it should satisfy several conflicting requirements: massive-scale, data-intensive, and mission-critical, the requirements of which have motivated the desired need for feasible IIoT network architecture. In particular, the traffic characteristics of certain IIoT applications feature small-data patterns especially in typical automation control scenarios such as robot control on the downlink. In order to reduce the huge overhead associated with each individual unicast transmission of the small-data message, we propose a novel “multipoint-to-multipoint” and/or “point-to-multipoint with different contents” communication paradigm-Uni-Multi-Unicast (UMUcast), which is based-on traditional 4G technologies such as evolved Multimedia Broadcast Multicast Service (eMBMS) and Group Communication System Enablers (GCSE), and novel 5G technologies such as Multi-Access Edge Computing (MEC). For the downlink, the UMUcast transmitter can jointly encode multiple-sources' small-data messages into a single chunk at MEC equipment in conjoint with a gNB, where chunk can be one-off transmission to multiple receivers simultaneously through an eMBMS frame, whereas the chunk is decoded into multiple small-data by each individual IIoT devices separately and respectively. The simulation results show that UMUcast has remarkable improvements over conventional point-to-point unicasting in handling multi-source, multi-destination, and massive small-data delivery with characteristics of low-overhead, high-throughput, and ultra-low-latency for future 5G-based IIoT networks.

LIGHTWEIGHT GROUP KEY MANAGEMENT FOR DATA DISSIMILATION FORDYNAMIC SDN MANET ENVIRONMENTS

The Internet of Things has grown the next big step in the development of that corresponding current Internet as well as communicates security protection as one of the most significant problems. In specific, use situations and deployment environments that adopt group communication systems need to be appropriately secured to protect the transfer of messages among group members from several safety assaults. A distinct way to secure group communication is based on the implementation of a symmetric group key distributed between all group members. This, in turn, needs focusing on a group key management system that is accountable for revoking and renewing the group key when nodes join or leave the group. The adopted group key management system should be effective and extremely scalable with the group size due to the resource-constrained nature of typical SDN systems.

A co-produced method to involve service users in research: the SUCCESS model

BackgroundPublic and patient involvement is a routine element of health services research methods to produce better designed and reported studies. Although co-production is recommended when involving people in research, methods for involving people are usually designed and managed by researchers and there is little evidence about methods to co-produce models for effective public and patient involvement. We report the method used by a group of patient and carer service users to develop and implement a model for involving public members in research.MethodWe recruited people with experience of chronic conditions, as patients and carers, and supported them to develop and implement the involvement model. We collected written records to describe the processes of co-production.ResultsSixteen service users were involved through a series of workshop, meeting and email discussions. They specified principles and operating characteristics of the model which concerned an inclusive culture, adequate resources, accessibility, good communication and clarity of purpose and roles. Components of the model included an on-line Panel of members (n = 20), Steering Group meetings, representation and communication system, facilitator, supportive research environment and access to research activities. Over 8 years, members were active in 218 research activities and held 22 Steering Group meetings. The model was named SUCCESS standing for Service Users with Chronic Conditions Encouraging Sensible Solutions.ConclusionWe supported patients and carers to co-produce the SUCCESS model of involvement in research. The model’s components, addressing their needs and priorities, led to sustained involvement in research over 8 years. Further work is needed to apply the model in different settings and assess impact of this method of involving people in research.

Design of power saving protocol with duty cycle adjustment for public safety-LTE

In this paper, a power saving protocol for public safety-long-term evolution (PS-LTE) with duty cycle adjustment is proposed according to the emergency of PS-LTE-based mobile stations. Because the PS-LTE transceiver consumes power whenever it is active, it is the most efficient to leave the receiver off, and wake it up asynchronously only when needed. As an alternative to protocol-based duty-cycle control, an asynchronous wake-up scheme is designed for battery saving of PS-LTE devices. This type of PS-LTE phones with power saving protocol has an adaptive cycle control during 'EMERGENCY-CALL'. This dedicated wake-up 'EMERGENCY PS-LTE Phone' can continuously monitor the channel, listening for a wake-up signal from other nodes and activating the main receiver upon the detection of asynchronous wake-up protocol. As a result, PS-LTE-based mobile station reduces power consumption by maximising the node sleeping-time without compromising network latency, and the wake-up PS-LTE phone with power saving protocol (without PS-LTE's function activities: group communication systems enabler, proximity-based service, mission critical push-to-talk, isolated E-UTRAN operation for public safety, relay, etc.) also enables the improvement of overall network performance.

A Fault-Tolerant Algorithm For Distributed Resource Allocation

Resource allocation is a usual problem that must be faced during a distributed system design. Despite the large number of algorithms proposed in literature to solve this problem, most papers lack of detailed descriptions about how to turn these algorithms into real-world reliable protocols. This article presents a fault-tolerant algorithm for distributed resource allocation named SLOTS which is implemented as an executable protocol. It allocates resources among members in a fairly manner using simple heuristics and employing a donation approach. SLOTS supports the dynamic behavior of clusters and provides high availability services. It bases its fault-tolerance properties and membership changes in atomic sets of operations (like transactions) using services provided by an underlying Group Communication System

Scalable and Anonymous Group Communication with MTor

Abstract This paper presents MTor, a low-latency anonymous group communication system. We construct MTor as an extension to Tor, allowing the construction of multi-source multicast trees on top of the existing Tor infrastructure. MTor does not depend on an external service to broker the group communication, and avoids central points of failure and trust. MTor’s substantial bandwidth savings and graceful scalability enable new classes of anonymous applications that are currently too bandwidth-intensive to be viable through traditional unicast Tor communication-e.g., group file transfer, collaborative editing, streaming video, and real-time audio conferencing. We detail the design of MTor and then analyze its performance and anonymity. By simulating MTor in Shadow and TorPS using realistic models of the live Tor network’s topology and recent consensus records from the live Tor network, we show that MTor achieves a 29% savings in network bandwidth and a 73% reduction in transmission time as compared to the baseline approach for anonymous group communication among 20 group members. We also demonstrate that MTor scales gracefully with the number of group participants, and allows dynamic group composition over time. Importantly, as more Tor users switch to group communication, we show that the overall performance and utilization for group communication improves. Finally, we discuss the anonymity implications of MTor and measure its resistance to traffic correlation.

Designing for geo-referenced in-situ therapeutic scenarios

Cognitive behavioral therapy and social competences and skills training sometimes rely on in-situ activities to improve the patients' condition. As the process evolves, therapists concede some autonomy to patients, allowing them to carry out those activities without the need for the former's presence. The ability to remotely track patient's activities provides an interesting solution to ensure their success, still encouraging their autonomy. This paper presents the design process and evaluation of a remote group monitoring and communication system for these two types of procedures. We use traditional group communication directives and augment them with geo-referenced information, empowering therapists with critical data to track their patients live and remotely. We describe the design process of a high-fidelity prototype and discuss the results from an experimental study that assessed the system from a usability and functionality perspectives. Results fueled an interesting discussion regarding how geo-referenced information help users maintaining awareness when multi-tasking.

Two-Level Software Architecture for Context-Aware Mobile Distributed Systems

Currently, there is a trend to develop context-aware mobile distributed systems (MDS), such as systems that recommend places according to the location and the path of users. Some of the key challenges in the development of this type of systems are the following: acquisition, management and use of data context. In this paper, we propose two-level software architecture to obtain, use and provide context information in a MDS. From our point of view, the proposed architecture takes into account the requirements that emerge from data collection, use and management of context, as well as the own features of MDS. Based on our software architecture, a context-aware group communication system is implemented, which allows members to have four types of context: physical activity, logical activity, location and level of sound.

Provably Secure Group Key Management Approach Based upon Hyper-Sphere

Secure group communication systems have become increasingly important for many emerging network applications. An efficient and robust group key management approach is indispensable to a secure group communication system. Motivated by the theory of hyper-sphere, this paper presents a new group key management approach with a group controller (GC). In our new design, a hyper-sphere is constructed for a group and each member in the group corresponds to a point on the hyper-sphere, which is called the member's private point. The GC computes the central point of the hyper-sphere, intuitively, whose “distance” from each member's private point is identical. The central point is published such that each member can compute a common group key, using a function by taking each member's private point and the central point of the hyper-sphere as the input. This approach is provably secure under the pseudo-random function (PRF) assumption. Compared with other similar schemes, by both theoretical analysis and experiments, our scheme (1) has significantly reduced memory and computation load for each group member; (2) can efficiently deal with massive membership change with only two re-keying messages, i.e., the central point of the hyper-sphere and a random number; and (3) is efficient and very scalable for large-size groups.

Efficient Resource Allocation in Multicasting over Mobile Adhoc Networks

A Mobile Ad-hoc Network (MANET) represents an ad-hoc network which are able to change locations; which can also perform self-configuration and self-organization in a dynamic environment. Group communication system plays a major part in MANET environment which are implemented by multicasting method which provides delivery of packets to a group of destination. But there are many difficulties in implementing scalable, optimized and efficient multicasting network in mobile ad-hoc network because managing a dynamic environment with group membership is a challenging process. Efficient Geographic Multicast Protocol (EGMP) is proposed which uses a virtual zone base structure. The geographic region is divided into many virtual zones. The Distance between the source and other nodes in the group are found and the one closest to source is chosen as cluster head or zone leader. Zone leader communicates with its group members. Only zone leader transmits data and hence the node does not receive the same packets again and again. EGMP greatly simplifies zone management and packet forwarding. EGMP uses geographic forwarding to provide reliable packet transmission. It ensures the successful transmission of the data packets, has low overhead and reduced redundant packet transmissions. Compared with Scalable Position Based Multicast (SPBM), simulation results of EGMP shows high packet delivery ratio thus packet missing while transmission are reduced hence re-transmission of packets are reduced and bandwidth is utilized efficiently.

Efficient Resource Allocation in Multicasting over Mobile Adhoc Networks

A Mobile Ad-hoc Network (MANET) represents an ad-hoc network which are able to change locations; which can also perform self-configuration and self-organization in a dynamic environment. Group communication system plays a major part in MANET environment which are implemented by multicasting method which provides delivery of packets to a group of destination. But there are many difficulties in implementing scalable, optimized and efficient multicasting network in mobile ad-hoc network because managing a dynamic environment with group membership is a challenging process. Efficient Geographic Multicast Protocol (EGMP) is proposed which uses a virtual zone base structure. The geographic region is divided into many virtual zones. The Distance between the source and other nodes in the group are found and the one closest to source is chosen as cluster head or zone leader. Zone leader communicates with its group members. Only zone leader transmits data and hence the node does not receive the same packets again and again. EGMP greatly simplifies zone management and packet forwarding. EGMP uses geographic forwarding to provide reliable packet transmission. It ensures the successful transmission of the data packets, has low overhead and reduced redundant packet transmissions. Compared with Scalable Position Based Multicast (SPBM), simulation results of EGMP shows high packet delivery ratio thus packet missing while transmission are reduced hence re-transmission of packets are reduced and bandwidth is utilized efficiently.

Architecture for mobile group communication in campus environment

The demand for group communication using smart devices in campus environment is increasing rapidly. In this paper, we design an architecture for a mobile group communication system (MGCS) on campus by using Wi-Fi networks and smart devices. The architecture is composed of a web-based system and a smart device based mobile system. Through the systems, users on campus create community/mobile group, maintain dynamic group membership, and reliably deliver the message to other users. We use the common features of many smart devices to develop a prototype that works on off-the-shelf hardware. In the experimental section, we demonstrate our system using various real scenarios which can occur in university campuses.

On the tradeoff between altruism and selfishness in MANET trust management

Mobile ad hoc and sensor networks may consist of a mixture of nodes, some of which may be considered selfish due to a lack of cooperativeness in providing network services such as forwarding packets. In the literature, existing trust management protocols for mobile ad hoc networks advocate isolating selfish nodes as soon as they are detected. Further, altruistic behaviors are encouraged with incentive mechanisms. In this paper, we propose and analyze a trust management protocol for group communication systems where selfish nodes exist and system survivability is highly critical to mission execution. Rather than always encouraging altruistic behaviors, we consider the tradeoff between a node’s individual welfare (e.g., saving energy to prolong the node lifetime) vs. global welfare (e.g., achieving a given mission with sufficient service availability) and identify the best design condition of this behavior model to balance selfish vs. altruistic behaviors. With the system lifetime and the mission success probability as our trust-based reliability metric, we show that our behavior model that exploits the tradeoff between selfishness vs. altruism outperforms one that only encourages altruistic behaviors.

센서 네트워크 기반의 다수 사용자간 Full-Duplex 음성 통신 시스템을 위한 TDMA/TDD MAC 프로토콜 설계

The IEEE 802.15.4 offers standard about PHY and MAC layer and features low power, low bandwidth, and low speed data communication. Because of this reason, IEEE 802.15.4 is only within a limited range such as sensor detection and home network; nevertheless, the research about transmission multimedia data like voice packet through wireless sensor networks is conducted widely. In this paper, we proposed the group communication system based on the sensor network. TDMA/TDD MAC based on the IEEE 802.15.4 PHY for voice communication on the sensor network is designed by improvement existing peer-to-peer voice communication on the sensor network and hardware is implemented for group communication. To measure the quality of designed system, mean opinion score (MOS) is obtained from the experiment and verified by using sine wave method. As a result of an experiment, we expect that a many cases of application solution can be developed using presented system.

On the Rekeying Load in Group Key Distributions Using Cover-Free Families

Key distributions based on cover-free families have been recently proposed for secure rekeying in group communication systems after multiple simultaneous user ejections. Existing literature has not quantified how difficult this rekeying operation might be. This study provides upper bounds on the number messages necessary to rekey a key distribution based on symmetric combinatorial designs after one or two simultaneous user ejections. Connections are made to results from finite geometry to show that these bounds are tight for certain key distributions. It is shown that in general determining the minimal number of messages necessary to rekey a group communication system based on a cover-free family is NP-hard.

A simulation process for asynchronous event processing systems: Evaluating performance and availability in transaction models

Simulation is essential for understanding the performance and availability behavior of complex systems, but there are significant difficulties when trying to simulate systems with multiple components, which interact with asynchronous communication. A systematic process is needed, in order to cope with the complexity of asynchronous event processing and the failure semantics of the interacting components. We address this problem by introducing an approach that combines formal techniques for faithful representation of the complex system effects and a statistical analysis for simultaneously studying multiple simulation outcomes, in order to interpret them. Our process has been successfully applied to a synthetic workload for distributed transaction processing. We outline the steps followed towards generating a credible simulation model and subsequently we report and interpret the results of the applied statistical analysis. This serves as a proof of concept that the proposed simulation process can be also effective in other asynchronous system contexts, like for example distributed group communication systems, file systems and so on.

Collusion resistant self-healing key distribution in mobile wireless networks

A fundamental concern of any secure group communication system is key management and wireless environments create new challenges. One core requirement in these emerging networks is self-healing. In systems where users can be offline and miss updates, self-healing allows a user to recover lost session keys and get back into the secure communication without putting extra burden on the group manager. Clearly, self-healing must only be available to authorised users. This paper fixes the problem of collusion attack in an existing self-healing key distribution scheme and provides a highly efficient scheme as compared to the existing works. It is computationally secure, resists collusion attacks made between newly joined users and revoked users and achieves forward and backward secrecy. Our security analysis is in an appropriate security model. Unlike the existing constructions, our scheme does not forbid revoked users from rejoining in later sessions.

와이브로망에서 VoIP를 이용한 그룹통신 서비스 성능분석

MBS (Multicast Broadcast Service) is defined in WiBro networks for implementing multicast-based services. However, most of the WiBro networks currently used in Korea do not have the MBS functionality and it causes some difficulty in implementing multicast-based services. This paper evaluates the performance of VoIP-based group communication services when implementing using the following two cases: unicast-based and multicast-based group communication systems. The performance evaluation is done using QualNet for each case in terms of the amount of network resource for the service, the delay and delay jitter of packets, and the difference of the delay of members in a group. The simulation result shows that the number of groups and members in a group in a WiBro network is limited because the amount of network resource for the service is increased according to the number of members in a group, and so, the MBS service is required in a WiBro network for a fully-fledged service of VoIP-based group communications. The simulation result also shows that, when a packet bundling is used, the number of groups and members in a group that can be supported in a WiBro network can be increased due to the decrease of the amount of network resource for the service. 키워드 와이브로, 그룹통신, VoIP, 패킷번들링