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Huang J.,University of Massachusetts Dartmouth | Wang H.,University of Massachusetts Dartmouth | Qian Y.,University of Nebraska at Omaha | Wang C.,InterDigital
IEEE Transactions on Smart Grid | Year: 2013

Smart grid can be visualized as an intelligent control system over sensors and communication platforms. Recently, wireless multimedia sensor networks (WMSNs) have shown its advantages for smart grid by providing rich surveillance information for grid failure detection and recovery, energy source monitoring, asset management, security, etc. On the other hand, cognitive radio (CR) networks have been identified as a key wireless technology to reduce the communication interferences and improve the bandwidth efficiency for smart grid communication. There is an essential need to use the CR communication platform to support large-size and time-sensitive multimedia delivery for future smart grid system. In this paper, we consider the heterogeneous characteristics of smart grid traffic including multimedia and propose a priority-based traffic scheduling approach for CR communication infrastructure based smart grid system according to the various traffic types of smart grid such as control commands, multimedia sensing data and meter readings. Specifically, we develop CR channel allocation and traffic scheduling schemes taking into consideration of channel switch and spectrum sensing errors, and solve a system utility optimization problem for smart grid communication system. Our solutions are demonstrated through both analyzes and simulations. This research opens a new vista of future smart grid communications. © 2012 IEEE. Source

Li H.,InterDigital | Cheng Y.,Illinois Institute of Technology | Zhou C.,Illinois Institute of Technology | Zhuang W.,University of Waterloo
IEEE Transactions on Parallel and Distributed Systems | Year: 2013

This paper studies how to select a path with the minimum expected end-to-end delay (EED) in a multiradio multichannel (MR-MC) wireless mesh network. While the existing studies mainly focus on the packet transmission delay due to medium access control (MAC), our new EED metric further takes into account the queuing delay at the MAC layer. In particular, in the MR-MC context, we develop a generic iterative approach to compute the multiradio achievable bandwidth (MRAB) for a path, taking the impact of inter-/intraflow interference and space/channel diversity into consideration. The MRAB is then combined with the EED to form the metric weighted end-to-end delay (WEED). As a byproduct of MRAB, a channel diversity coefficient is defined to quantitatively represent the channel diversity for a given path. Moreover, we design and implement a distributed WEED-based routing protocol for MR-MC wireless networks by extending the well-known AODV protocol. Extensive simulation results are presented to demonstrate the performance of EED/WEED-based routing, with comparison to some existing well-known routing metrics. © 1990-2012 IEEE. Source

Bogale T.E.,University of Quebec | Le L.B.,University of Quebec | Haghighat A.,InterDigital | Vandendorpe L.,Catholic University of Louvain
IEEE Transactions on Wireless Communications | Year: 2016

This paper considers hybrid beamforming (HB) for downlink multiuser massive multiple-input multiple-output (MIMO) systems with frequency selective channels. The proposed HB design employs sets of digitally controlled phase (fixed phase) paired phase shifters (PSs) and switches. For this system, first we determine the required number of radio frequency (RF) chains and PSs such that the proposed HB achieves the same performance as that of the digital beamforming (DB) which utilizes N (number of transmitter antennas) RF chains. We show that the performance of the DB can be achieved with our HB just by utilizing rt RF chains and 2rt(N - rt + 1) PSs, where rt ≤ N is the rank of the combined digital precoder matrices of all subcarriers. Second, we provide a simple and novel approach to reduce the number of PSs with only a negligible performance degradation. Numerical results reveal that only 20-40 PSs per RF chain are sufficient for practically relevant parameter settings. Finally, for the scenario where the deployed number of RF chains (Na) is less than rt, we propose a simple user scheduling algorithm to select the best set of users in each subcarrier. Simulation results validate theoretical expressions, and demonstrate the superiority of the proposed HB design over the existing HB designs in both flat fading and frequency selective channels. © 2016 IEEE. Source

Cartmell J.R.,InterDigital
Proceedings of the IASTED International Conference on Communication, Internet, and Information Technology, CIIT 2012 | Year: 2012

IP Flow Mobility (IFOM) is a feature defined in the 3GPP standards. In this paper we propose a Converged Gateway (CGW) which enables IFOM to perform seamless offload from licensed spectrum to unlicensed spectrum. The IFOM functionality within the CGW takes into account the current conditions, rules provisioned from the Evolved Packet Core (EPC) network and local administrator rules that are merged with the rules provisioned from the core network. The CGW will manage IP Flows from their inception until their end. It will decide the optimal link to use for the delivery of data to an end-user device. Routing rules are used to decide the initial access assignment of an IP Flow. Once an IP Flow has been identified by Deep Packet Inspection (DPI), it will be placed on the access according to its type and the rule for that type. Periodically, the CGW will perform load balancing and handling link-down scenarios to most effectively utilize the links. We then show a few examples based on a set of rules and flow types. Source

Zuniga J.C.,InterDigital | Bernardos C.J.,Charles III University of Madrid | De La Oliva A.,Charles III University of Madrid | Melia T.,Polytechnic University of Turin | And 2 more authors.
IEEE Communications Magazine | Year: 2013

In this article, we introduce distributed mobility management (DMM) - a new architectural paradigm for evolving mobile IP networks. We discuss the technology trends that are driving a move toward DMM and what the relevant standards development organizations (IETF and 3GPP) are doing to address these new needs. We conclude with a discussion of how 3GPP's evolved packet core can evolve toward a DMM-based architecture. © 1979-2012 IEEE. Source

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