Readiness in deployment and flexibility in radio resource configuration are the main features of future wireless communication systems. A cooperative wireless communication system (CWCS) is proposed to follow the same principle, aiming at improving the overall performance of a wireless system with the support of advanced beam-hopping techniques. In this article, we propose a multiloop radio resource management mechanism for the CWCS based on the organized beam-hopping (OBH) technique. The proposed RRM mechanism enhances the robustness of the CWCS, based on the OBH technique working with fast temporal-spatial variant traffic. The results show that the system performance can be further improved by hybrid transmission and event- driven access management techniques.
"The performance of OBH is shown to be superior to opportunistic beamforming for all levels of mobile populations in a cell. Gains in spectral efficiency of 1 b/s/Hz by OBH over both opportunistic beamforming and coherent beamforming were demonstrated in . Results were obtained through simulation of a cellular system comprised of cells with a 1 km cell radius, each having six beams per cell (i.e., 60 degree sectors ). "
[Show abstract][Hide abstract] ABSTRACT: This article provides an overview of contemporary and forward looking inter-cell interference coordination techniques for 4G OFDM systems with a specific emphasis on implementations for LTE. Viable approaches include the use of power control, opportunistic spectrum access, intra and inter-base station interference cancellation, adaptive fractional frequency reuse, spatial antenna techniques such as MIMO and SDMA, and adaptive beamforming, as well as recent innovations in decoding algorithms. The applicability, complexity, and performance gains possible with each of these techniques based on simulations and empirical measurements will be highlighted for specific cellular topologies relevant to LTE macro, pico, and femto deployments for both standalone and overlay networks.
[Show abstract][Hide abstract] ABSTRACT: Spinal fusion has become a widely used technique to treat a variety of spinal instability syndromes including those due to trauma, tumor, infection, degeneration, and deformity. Spinal fusion is always performed using bone graft with or without stabilizing implants. The degree of the associated instability usually determines the necessity of implants. Instrumentation of the spine has undergone revolutionary changes over the past decade. It has evolved from the use of only wire, to wire holding rods, to rods with hooks, to universal systems which include hooks, wires, pedicle screws, and rods or plates. Rods and plates can be contoured to enable segmental maneuvering of the individual vertebrae
Engineering in Medicine and Biology Society, 1997. Proceedings of the 19th Annual International Conference of the IEEE; 01/1997
[Show abstract][Hide abstract] ABSTRACT: Relay selection schemes for cooperative communications to achieve full cooperative diversity gains while maintaining spectral and energy efficiency have been extensively studied in recent research. These schemes select only the best relay from multiple relaying candidates to cooperate with a communication link. In this paper, we review recently proposed cooperative communication protocols which integrate with relay selection mechanisms. The key design issues for relay selection mechanisms, e.g., relaying candidate selection, optimal relay assignment, and cooperative transmission, are identified. We further discuss the challenges of optimal relay assignment in multi-hop wireless sensor networks, and present the potential applications of cooperative communications with relay selection in such networks. Future research directions are outlined, e.g., the issues of service differentiation and system fairness in cooperative communication systems, and the joint use of game theory and machine learning techniques in relaying candidate selection and optimal relay assignment mechanisms for efficient allocation of network resources.
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