The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ender Ayanoglu - One of the best experts on this subject based on the ideXlab platform.
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millimeter wave massive mimo downlink per Group Communications with hybrid linear precoding
IEEE Transactions on Vehicular Technology, 2021Co-Authors: Thomas Ketseoglou, Matthew C Valenti, Ender AyanogluAbstract:We address the problem of analyzing and classifying into Groups the downlink channel environment in a dense millimeter-wavelength cell, accounting for path loss, multipath fading, and User Equipment (UE) blocking, by employing a hybrid propagation and multipath fading model, thus using accurate inter-Group interference modeling. The base station (BS) employs a large Uniform Planar Array (UPA) to facilitate massive Multiple-Input, Multiple-Output (MIMO) Communications with high efficiency. UEs are equipped with a single antenna and are distributed uniformly within the cell. The key problem is analyzing and defining Groups toward efficient precoding. Because balanced throughput is desired between Groups, up to four separate frequency sub-carriers are employed in an Orthogonal Frequency Division Multiple Access (OFDMA) system. We show that by employing three or four OFDMA subcarriers, depending on the number of UEs in the cell and the cell range, the UEs can be efficiently separated into high-throughput Groups, with each Group employing Virtual Channel Model Beams (VCMB) based inner precoding, followed by efficient Multi-User Multiple-Input Multiple-Output (MU-MIMO) outer precoders. For each Group, we study two different sub-Grouping methods offering different advantages. We show that the improvement offered by Zero-Forcing Per-Group Precoding (ZF-PGP) over Matched Filter Precoding (MFP) and Zero-Forcing Precoding (ZFP) is very high when finite-alphabet inputs are used. We also show ZF-PGP with finite-alphabet inputs significantly outperforms MFP with Gaussian inputs in certain realistic setups. Finally, a new technique for power allocation among different UEs is proposed, called Optimized Per-Group Power Allocation (OPGPA), which achieves much higher power efficiency jointly with equal throughput among all UEs in each Group.
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millimeter wave massive mimo downlink per Group Communications with hybrid linear precoding
Asilomar Conference on Signals Systems and Computers, 2019Co-Authors: Thomas Ketseoglou, Matthew C Valenti, Ender AyanogluAbstract:We address the problem of analyzing and classifying in Groups the downlink channel environment in a millimeter- wavelength cell, accounting for path loss, multipath fading, and User Equipment (UE) blocking, by employing a hybrid propagation and multipath fading model, thus using accurate inter-Group interference modeling. The base station (BS) employs a large Uniform Planar Array (UPA) to facilitate massive Multiple-Input, Multiple-Output (MIMO) Communications with high efficiency. UEs are equipped with a single antenna and are distributed uniformly within the cell. The key problem is analyzing and defining Groups toward precoding. Because equitable throughput is desired between Groups, Combined Frequency and Spatial Division and Multiplexing (CFSDM) is found to be necessary. We show that by employing three subcarrier frequencies, the UEs can be efficiently separated into high throughput Groups, with each Group employing Virtual Channel Model Beams (VCMB) based inner precoding, followed by efficient Multi-User MultipleInput Multiple-Output (MU-MIMO) outer precoders. For each Group, we study three different sub-Grouping methods offering different advantages. We show that the improvement offered by Zero-Forcing Per-Group Precoding (ZF-PGP) over Zero-Forcing Precoding (ZFP) is very high.
Shianzhang Fang - One of the best experts on this subject based on the ideXlab platform.
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a hierarchical key management scheme for secure Group Communications in mobile ad hoc networks
Journal of Systems and Software, 2007Co-Authors: Nenchung Wang, Shianzhang FangAbstract:A mobile ad hoc network (MANET) is a kind of wireless communication infrastructure that does not have base stations or routers. Each node acts as a router and is responsible for dynamically discovering other nodes it can directly communicate with. However, when a message without encryption is sent out through a general tunnel, it may be maliciously attacked. In this paper, we propose a hierarchical key management scheme (HKMS) for secure Group Communications in MANETs. For the sake of security, we encrypt a packet twice. Due to the frequent changes of the topology of a MANET, we also discuss Group maintenance in this paper. Finally, we conducted the security and performance analysis to compare the proposed scheme with Tseng et al.'s [Tseng, Y.-M., Yang, C.-C., Liao, D.-R., 2007. A secure Group communication protocol for ad hoc wireless networks. In: Advances in Wireless Ad Hoc and Sensor Networks and Mobile Computing. Book Series Signal and Communication Technology. Springer] and Steiner et al.'s [Steiner, M., Tsudik, G., Waidner, M., 1998. CLIQUES: a new approach to Group key agreement. In: Proceedings of the 18th IEEE International Conference on Distributed Computing System. Amsterdam, Netherlands, pp. 380-387] schemes.
Bobby Bhattacharjee - One of the best experts on this subject based on the ideXlab platform.
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a scalable key management and clustering scheme for wireless ad hoc and sensor networks
Future Generation Computer Systems, 2008Co-Authors: Jason H Li, Bobby Bhattacharjee, Miao Yu, Renato LevyAbstract:This paper describes a scalable key management and clustering scheme for secure Group Communications in ad hoc and sensor networks. The scalability problem is solved by partitioning the communicating devices into subGroups, with a leader in each subGroup, and further organizing the subGroups into hierarchies. Each level of the hierarchy is called a tier or layer. Key generation, distribution, and actual data transmissions follow the hierarchy. The distributed, efficient clustering approach (DECA) provides robust clustering to form subGroups, and analytical and simulation results demonstrate that DECA is energy-efficient and resilient against node mobility. Comparing with most other schemes, our approach is extremely scalable and efficient, provides more security guarantees, and is selective, adaptive and robust.
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scalable secure Group communication over ip multicast
IEEE Journal on Selected Areas in Communications, 2002Co-Authors: Suman Banerjee, Bobby BhattacharjeeAbstract:We introduce and analyze a scalable rekeying scheme for implementing secure Group Communications Internet protocol multicast. We show that our scheme incurs constant processing, message, and storage overhead for a rekey operation when a single member joins or leaves the Group, and logarithmic overhead for bulk simultaneous changes to the Group membership. These bounds hold even when Group dynamics are not known a priori. Our rekeying algorithm requires a particular clustering of the members of the secure multicast Group. We describe a protocol to achieve such clustering and show that it is feasible to efficiently cluster members over realistic Internet-like topologies. We evaluate the overhead of our own rekeying scheme and also of previously published schemes via simulation over an Internet topology map containing over 280 000 routers. Through analysis and detailed simulations, we show that this rekeying scheme performs better than previous schemes for a single change to Group membership. Further, for bulk Group changes, our algorithm outperforms all previously known schemes by several orders of magnitude in terms of actual bandwidth usage, processing costs, and storage requirements.
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scalable secure Group communication over ip multicast
International Conference on Network Protocols, 2001Co-Authors: Suman Banerjee, Bobby BhattacharjeeAbstract:We introduce and analyze a scalable re-keying scheme for implementing secure Group Communications over IP multicast. We show that our scheme incurs constant processing, message, and storage overhead for a re-key operation when a single member joins or leaves the Group, and logarithmic overhead for bulk simultaneous changes to the Group membership. These bounds hold even when Group dynamics are not known a priori. Our re-keying algorithm requires a particular clustering of the members of the secure multicast Group. We describe a protocol to achieve such clustering and show that it is feasible to efficiently cluster members over realistic Internet-like topologies. We evaluate the overhead of our own re-keying scheme and also of previously published schemes via simulation over an Internet topology map containing over 280,000 routers. Through analysis and detailed simulations, we show that this re-keying scheme performs better than previous schemes for a single change to Group membership. Further, for bulk changes, our algorithm outperforms all previously known schemes by several orders of magnitude in terms of actual bandwidth usage, processing costs and storage requirements.
K J R Liu - One of the best experts on this subject based on the ideXlab platform.
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hierarchical Group access control for secure multicast Communications
IEEE ACM Transactions on Networking, 2007Co-Authors: Yan Sun, K J R LiuAbstract:Many Group Communications require a security infrastructure that ensures multiple levels of access control for Group members. While most existing Group key management schemes are designed for single level access control, we present a multi-Group key management scheme that achieves hierarchical Group access control. Particularly, we design an integrated key graph that maintains keying material for all members with different access privileges. It also incorporates new functionalities that are not present in conventional multicast key management, such as user relocation on the key graph. Analysis is performed to evaluate the storage and communication overhead associated key management. Comprehensive simulations are performed for various application scenarios where users statistical behavior is modelled using a discrete Markov chain. Compared with applying existing key management schemes directly to the hierarchical access control problem, the proposed scheme significantly reduces the overhead associated with key management and achieves better scalability.
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analysis and protection of dynamic membership information for Group key distribution schemes
IEEE Transactions on Information Forensics and Security, 2007Co-Authors: K J R LiuAbstract:In secure Group-oriented applications, key management schemes are employed to distribute and update keys such that unauthorized parties cannot access Group Communications. Key management, however, can disclose information about the dynamics of Group membership, such as the Group size and the number of joining and departing users. This is a threat to applications with confidential Group membership information. This paper investigates techniques that can stealthily acquire Group dynamic information from key management. We show that insiders and outsiders can successfully obtain Group membership information by exploiting key establishment and key updating procedures in many popular key management schemes. Particularly, we develop three attack methods targeting tree-based centralized key management schemes. Further, we propose a defense technique utilizing batch rekeying and phantom users, and derive performance criteria that describe security level of the proposed scheme using mutual information. The proposed defense scheme is evaluated based on the data from MBone multicast sessions. We also provide a brief analysis on the disclosure of Group dynamic information in contributory key management schemes
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scalable hierarchical access control in secure Group Communications
International Conference on Computer Communications, 2004Co-Authors: Yan Sun, K J R LiuAbstract:Many Group Communications require a security infrastructure that ensures multiple levels of access privilege for Group members. Access control in hierarchy is prevalent in multimedia applications, which consist of users that subscribe to different quality levels or different sets of data streams. We present a multi-Group key management scheme that achieves such a hierarchical access control by employing an integrated key graph and by managing Group keys for all users with various access privileges. Compared with applying existing tree-based Group key management schemes directly to the hierarchical access control problem, the proposed scheme significantly reduces the communication, computation and storage overhead associated with key management and achieves better scalability when the number of access levels increases. In addition, the proposed key graph is suitable for both centralized and contributory environments.
Nirwan Ansari - One of the best experts on this subject based on the ideXlab platform.
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security services in Group Communications over wireless infrastructure mobile ad hoc and wireless sensor networks
IEEE Wireless Communications, 2007Co-Authors: P Sakarindr, Nirwan AnsariAbstract:Group Communications in wireless networks has been facilitating many emerging applications that require packet delivery from one or more sender(s) to multiple receivers. Due to insecure wireless channels, Group Communications are susceptible to various kinds of attacks. Although a number of proposals have been reported to secure Group Communications, provisioning security in Group Communications in wireless networks remains a critical and challenging issue. This article presents a survey of recent advances in security requirements and services in Group Communications in three types of wireless networks, and discusses challenges in designing secure Group Communications in these networks: wireless infrastructure networks, mobile ad hoc networks, and wireless sensor networks.
