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Proceedings ArticleDOI

Energy efficient algorithm for MIMO based CRN with antenna selection

17 Mar 2016-pp 1024-1028
TL;DR: An antenna selection algorithm is proposed which has lesser computations to be performed and the results of the channel capacity are compared with that of exhaustive search for various antenna configurations.
Abstract: To enhance the transmission efficiency of wireless communications systems, there is extensive research going on in the field of Cognitive Radio network along with the improvement in antenna technology. Use of multiple RF devices for various applications increases the need of multiple antennas at the transceiver which results in more computational complexity and large power consumption at high data rates. Incorporating the spectrum sensing abilities of Cognitive Radio for higher spectrum efficiency along with MIMO technology increases the need to determine the optimum power levels for the antennas at which data transmission takes place. To overcome the challenges for optimizing energy efficiency, we propose an efficient algorithm to compute the transmit-power that is to be allocated using water filling method and antenna subset selection schemes. For this, an antenna selection algorithm is proposed which has lesser computations to be performed and the results of the channel capacity are compared with that of exhaustive search for various antenna configurations.
References
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Journal ArticleDOI
Wei Yu1, Tian Lan1
TL;DR: It is shown that various notions of uplink-downlink duality may be unified under a Lagrangian duality framework and this new interpretation of duality gives rise to efficient numerical optimization techniques for solving the downlink per-antenna transmitter optimization problem.
Abstract: This paper considers the transmitter optimization problem for a multiuser downlink channel with multiple transmit antennas at the base-station. In contrast to the conventional sum-power constraint on the transmit antennas, this paper adopts a more realistic per-antenna power constraint, because in practical implementations each antenna is equipped with its own power amplifier and is limited individually by the linearity of the amplifier. Assuming perfect channel knowledge at the transmitter, this paper investigates two different transmission schemes under the per-antenna power constraint: a minimum-power beamforming design for downlink channels with a single antenna at each remote user and a capacity-achieving transmitter design for downlink channels with multiple antennas at each remote user. It is shown that in both cases, the per-antenna downlink transmitter optimization problem may be transformed into a dual uplink problem with an uncertain noise. This generalizes previous uplink-downlink duality results and transforms the per-antenna transmitter optimization problem into an equivalent minimax optimization problem. Further, it is shown that various notions of uplink-downlink duality may be unified under a Lagrangian duality framework. This new interpretation of duality gives rise to efficient numerical optimization techniques for solving the downlink per-antenna transmitter optimization problem

873 citations


Additional excerpts

  • ...1 1 2 { } 0 log det arg max R subopt H x N p p p E p I H H QN   = +     (7)...

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Book
25 Mar 1988
TL;DR: In this article, the authors present a resource allocation approach for resource allocation problems in the ORS problem, using an algorithm based approach, which they call Algorithmic Approaches.
Abstract: (1989). Resource Allocation Problems: Algorithmic Approaches. Journal of the Operational Research Society: Vol. 40, No. 7, pp. 701-702.

705 citations


Additional excerpts

  • ..., T i x i N N i r E γ μ λ +   = − =     (4)...

    [...]

Journal ArticleDOI
TL;DR: The purpose of this paper is to provide a practical algorithm to evaluate numerically a general waterfilling solution, which includes the currently existingWaterfilling solutions and others that may possibly appear in future problems.
Abstract: Many engineering problems that can be formulated as constrained optimization problems result in solutions given by a waterfilling structure; the classical example is the capacity-achieving solution for a frequency-selective channel. For simple waterfilling solutions with a single waterlevel and a single constraint (typically, a power constraint), some algorithms have been proposed in the literature to compute the solutions numerically. However, some other optimization problems result in significantly more complicated waterfilling solutions that include multiple waterlevels and multiple constraints. For such cases, it may still be possible to obtain practical algorithms to evaluate the solutions numerically but only after a painstaking inspection of the specific waterfilling structure. In addition, a unified view of the different types of waterfilling solutions and the corresponding practical algorithms is missing. The purpose of this paper is twofold. On the one hand, it overviews the waterfilling results existing in the literature from a unified viewpoint. On the other hand, it bridges the gap between a wide family of waterfilling solutions and their efficient implementation in practice; to be more precise, it provides a practical algorithm to evaluate numerically a general waterfilling solution, which includes the currently existing waterfilling solutions and others that may possibly appear in future problems.

501 citations

Journal ArticleDOI
TL;DR: The scope of this work is to give an overview of the problem of spectrum assignment in cognitive radio networks, presenting the state-of-the-art proposals that have appeared in the literature, analyzing the criteria for selecting the most suitable portion of the spectrum and showing the most common approaches and techniques used to solve the spectrum assignment problem.
Abstract: Cognitive radio (CR) has emerged as a promising technology to exploit the unused portions of spectrum in an opportunistic manner. The fixed spectrum allocation of governmental agencies results in unused portions of spectrum, which are called "spectrum holes" or "white spaces". CR technology overcomes this issue, allowing devices to sense the spectrum for unused portions and use the most suitable ones, according to some pre-defined criteria. Spectrum assignment is a key mechanism that limits the interference between CR devices and licensed users, enabling a more efficient usage of the wireless spectrum. Interference is a key factor that limits the performance in wireless networks. The scope of this work is to give an overview of the problem of spectrum assignment in cognitive radio networks, presenting the state-of-the-art proposals that have appeared in the literature, analyzing the criteria for selecting the most suitable portion of the spectrum and showing the most common approaches and techniques used to solve the spectrum assignment problem. Finally, an analysis of the techniques and approaches is presented, discussing also the open issues for future research in this area.

382 citations

Journal ArticleDOI
TL;DR: The state-of-art results on communication resource allocation over space, time, and frequency for emerging cognitive radio (CR) wireless networks are provided and convex optimization plays an essential role in solving these problems, in a both rigorous and efficient way.
Abstract: This article provides an overview of the state-of-art results on communication resource allocation over space, time, and frequency for emerging cognitive radio (CR) wireless networks Focusing on the interference-power/interference-temperature (IT) constraint approach for CRs to protect primary radio transmissions, many new and challenging problems regarding the design of CR systems are formulated, and some of the corresponding solutions are shown to be obtainable by restructuring some classic results known for traditional (non-CR) wireless networks It is demonstrated that convex optimization plays an essential role in solving these problems, in a both rigorous and efficient way Promising research directions on interference management for CR and other related multiuser communication systems are discussed

343 citations