Group Communication Environment Research Articles

Resource-efficient seamless transitions for high-performance multi-hop UAV multicasting

Many UAV-related applications require group communications between UAVs to reliably and efficiently deliver rich media content as well as to extend line-of-sight coverage between sky and ground. This paper is among the first to study fast yet resource-efficient UAV transitions for aerial group communications while maintaining high group communication performance. We develop a set of novel analytic and algorithmic results to form the efficient transition formation (ETF) algorithm, in order to deal with different UAV transition scenarios in a group communication environment. The ETF algorithm first evaluates the seamlessness of a straight-line trajectory (SLT) by processing low-complexity computations (e.g., Euclidean distances) or fast checks with controlled traffic overheads. For a non-seamless SLT, the ETF algorithmm establishes a new trajectory consisting of a minimal number of seamless straight lines that join at specially selected locations to control mobile UAVs’ seamless travel distances. Our simulation studies quantify the performance gains that the ETF algorithm may achieve, outperforming compared studies by admitting 66% more traffic with reduced energy consumption and guaranteed communication performance for both transitional and non-transitional UAVs.

Protecting patient privacy from unauthorized release of medical images using a bio-inspired wavelet-based watermarking approach

This paper identifies a novel digital watermarking approach for copyright protection and authentication of medical images based on the wavelet transformation. We consider the problem of protecting [email protected]? medical records and tracing illegally distributed medical images in a group communication environment. We employ the particle swarm algorithm and genetic algorithm optimization principles to obtain performance improvement in our work. In the proposed method, the strength of the embedded watermark and noise are controlled to prevent the images from being used directly regarding to visual properties of the host signal. These parameters and also the places of the embedded watermarks are varied to find the most suitable ones for images with different characteristics. The experimental results show that the proposed algorithm yields a watermark which is invisible to human eyes, robust against a wide variety of common attacks and reliable enough for tracing colluders.

Chosen ciphertext secure authenticated group communication using identity-based signcryption

Efficient access control with scalable rekeying is one of the most important requirements for secure group communications, especially in a dynamic and large group. In a many-to-many group communication environment, sender authentication is also another important security requirement as each participant can potentially be both a sender and a receiver. In this study, we propose an authenticated group communication scheme which is secure against an adaptive chosen ciphertext attack using identity-based signcryption. The proposed scheme allows multiple senders to dynamically multicast messages into an arbitrary group of receivers determined by the senders. In the proposed scheme, the group member can be a stateless receiver. Data confidentiality of the group communication is guaranteed as well as the sender authentication.

How Conversations Change Over Time in Face-to-Face and Video-Mediated Communication

An experiment was conducted to examine how communication patterns and task performance differ as a function of the group's communication environment and how these processes change over time. In a longitudinal design, three-person groups had to select and argue the correct answer out of a set of three alternatives for ten questions. Compared with face-to-face groups, video-teleconferencing groups took fewer turns, required more time for turns, and interrupted each other less. Listeners appeared to be more polite, waiting for a speaker to finish before making their conversational contribution. Although groups were able to maintain comparable performance scores across communication conditions, initial differences between conditions in communication patterns disappeared over time, indicating that the video-teleconferencing groups adapted to the newness and limitations of their communication environment. Moreover, because of increased experience with the task and the group, groups in both conditions needed less conversation to complete the task at later rounds. Implications are discussed for practice, training, and possibilities for future research.

이동 애드혹 네트워크에서 안전한 멀티캐스트 통신을 위한 효율적인 그룹 키 분배 방식

Secure delivery of multicast data can be achieved with the use of a group key for data encryption in mobile ad hoc network (MANET) applications based on the group communication. However, for the support of dynamic group membership, the group key has to be updated for each member joining/leaving and, consequently, a mechanism distributing an updated group key to members is required. The two major categories of the group key distribution mechanisms proposed for wired networks are the naive and the tree-based approaches. The naive approach is based on unicast, so it is not appropriate for large group communication environment. On the other hand, the tree-based approach is scalable in terms of the group size, but requires the reliable multicast mechanism for the group key distribution. In the sense that the reliable multicast mechanism requires a large amount of computing resources from mobile nodes, the tree-based approach is not desirable for the small-sized MANET environment. Therefore, in this paper, we propose a new key distribution protocol, called the proxy-based key management protocol (PROMPT), which is based on the naive approach in the small-sized MANET environment. PROMPT reduces the message overhead of the naive through the first-hop grouping from a source node and the last-hop grouping from proxy nodes using the characteristics of a wireless channel.

Protecting patient privacy against unauthorized release of medical images in a group communication environment

In this paper, we identify and study an important patient privacy protection problem related to medical images. Following Health Insurance Portability and Accountability Act (HIPAA) mandate on privacy protection of patients' medical records, efforts have been devoted to guaranteeing the confidentiality of data and medical images during storage and transmission via an untrustworthy channel. However, to our knowledge, there has not been any effort towards protecting against unauthorized release of images by an authorized recipient. In this paper, we study the problem of tracing illegally distributed medical images in a group communication environment and identify a set of design requirements that must be met. We propose a fingerprint model suitable for many-to-many multicast, that is computationally efficient and scalable in user storage and key update communication. Simulation results also show that our scheme is highly robust to typical medical image processing and collusion attacks, while yielding high quality watermarked images.

Group communication models

This paper presents an abstract model of an ODP-based group communication platform. The focus of this paper is on the computational and engineering models of a group communication environment. The group interaction requirements of advanced cooperative applications structured as an object-group are identified, and the distributed object models for group support are presented. The paper develops the notion of a policy-driven group support machine which can be used as a prototype model for integration in object-based platforms such as CORBA, DCE and TINA-DPE.