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Orthogonal frequency division multiplexing access (OFDMA) inherently suffers from large spectral sidelobes, which will lead to interference between users and can not be ignored. In this paper, in order to suppress spectral sidelobes, we propose a novel windowing scheme. The derivation of the optimum window function is based on the solution of an optimization problem. It aims to minimize in-band-out-of-subband...
Heterogeneous network (HetNet) has been widely accepted as a viable way to deal with the increasing traffic demand. However, the deployment of small cell base stations (SBSs) inevitably triggers a tremendous escalation of energy consumption. In this paper, we study the energy efficient HetNet deployment problem taking the disparities of the traffic load distribution into account. The optimization...
Energy efficiency (EE) is becoming one of the important criteria in wireless transmission design. This paper discusses the recently proposed energy-efficient transmit beamforming designs for multicell multiuser multiple-input single-output (MISO) systems, including maximizing overall network EE, sum weighted EE and fairness EE. Generally, the EE optimization problems are NP-hard nonconvex programs...
This paper focuses on an average robust transmit beamforming optimization problem for the multiuser multiple-input-single-output (MISO) downlink scenario. In this problem, the channels are modeled as Gaussian variables with mean zero and with known covariance at the transmitter. The design criterion is to maximize the sum of the users' average rates with respect to the channels, subject to the total...
In the recent networks, a multiuser downlink MIMO-OFDM (Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing) systems associated with Coordinated Multipoint (CoMP) technique ensures to fulfill the individual rate target across all users is considered. The CoMP technique enables to share the channel superiority measurements and schedules the transmissions, allowing for more efficient...
In this paper, we propose a novel iterative algorithm based on successive convex approximation for the nonconvex energy efficiency optimization problem in massive MIMO networks. The stationary points of the original problem are found by solving a sequence of successively refined approximate problems, and the proposed algorithm has the following advantages: 1) fast convergence as the structure of the...
A key challenge in wireless networks is to control and minimize power. In this paper, we study a total power minimization problem subject to power and Signal-to-Interference-plus-Noise Ratio (SINR) constraints in wireless networks with multiple independent channels. The objective is to minimize the total transmission power of the system while the sum rate targets of channels are satisfied. However,...
In this paper, we study the problem of resource allocation for an opportunistic spectrum-sharing channel under the assumption of statistical channel state information (CSI). More specifically, we assume that statistical CSI of the channels between both primary and secondary transmitters and the primary receiver is available at the secondary transmitter. We investigate the achievable rate maximization...
Several distributed coordinated precoding methods relying on over-the-air (OTA) iterations in time-division duplex (TDD) networks have recently been proposed. Each OTA iteration incurs overhead, which reduces the time available for data transmission. In this work, we therefore propose an algorithm which reaches good sum rate performance within just a few number of OTA iterations, partially due to...
In this paper, we study a resource efficient coordinated beamforming design for the downlink of heterogeneous multiuser system. The objective function is formulated as maximizing the weighted sum per-cell resource efficiencies subject to per-user quality of service demands and per-cell transmit power constraints, which is hard to tackle due to the weighted sum-of-ratios form and the non-convex nature...
We study the joint resource allocation problem of a mobile heterogeneous network composed of macro cellular users and Device-to-Device (D2D) links. Macro cellular users are always scheduled on uplink shared resources, whereas D2D links may use uplink shared resources, orthogonal resources reserved exclusively for D2D transmissions, or a combination of both types of resources. A sum utility maximization...
Device-to-Device (D2D) is an emerging technology that is typically employed as an underlay of the uplink (UL) cellular networks. The downlink cellular spectrum, however, is rarely reused by D2D links due to the strong interference from the base station to the D2D receivers. To this end, we propose to enable D2D transmissions in the downlink by multiplexing D2D and cellular users using beamforming...
Cognitive radio (CR) is an effective technology to deal with the spectrum scarcity and improve spectrum utilization. The growing small-cell is another effective method to enhance the spectrum efficiency of wireless networks by way of the spatial reuse of frequencies. In this paper, we consider a Multiple Input Multiple Output (MIMO) CR in small-cell networks and propose an efficient algorithm joint...
This paper focuses on the resource allocation within an asynchronous ad hoc network that utilizes two different modulation techniques: orthogonal frequency-division multiplexing (OFDM) and filter bank based multicarrier (FBMC). More specifically, we investigate the problem of downlink sum rate maximization. The NP-hard formulation is first decomposed into two subproblems in order to decrease the computational...
We consider physical-layer security in a novel MISO cooperative overlay cognitive radio network (CRN) with a single eavesdropper. We aim to design an artificial noise (AN) aided secondary transmit strategy to maximize the joint achievable secrecy rate of both primary and secondary links, subject to a global secondary transmit power constraint and guaranteeing any transmission of secondary should at...
We consider optimization of the multi-robot task-allocation problem when the overall performance of the team need not be a standard sum-of-cost model. We introduce a generalization that allows for the additional cost incurred by resource contention to be treated in a straightforward manner. In this variant, robots may choose one of shared resources to perform a task, and interference may be modeled...
Opportunistic traffic offloading has been proposed to tackle overload problems in cellular networks. However, they only address the problem of deadline-based content propagation in the cellular system, given wireless environment characterization. In contrast, we cope with the traffic offloading issue from another perspective: the base station interference coordination problem. In particular, we aim...
In this paper, we study the influence of network entity load constraints on network resource allocation. We focus on the problem of allocating network resources to optimize the total utility of multiple users in a wireless network, taking into account four resource and social requirements: 1) user QoS rate constraints, 2) node max load constraints, 3) node load balance constraints, and 4) node-user...
We consider a multi-pair two-way relay network with multiple single antenna amplify-and-forward relays. The sum rate maximization problem subject to a total transmit power constraint is studied for such network. The optimization problem is non-convex. First, we show that the problem is a monotonic optimization problem and propose a polyblock approximation algorithm for obtaining the global optimum...
In recent years, cognitive radio technology (CR) has been proposed to allow unlicensed secondary users (SUs) to opportunistically access the channels unused by primary users. As a result, there is a lot of recent interests on studying cognitive radio cellular networks (CogCells) that can support both PUs and SUs. Due to the limited transmission range of SUs, in this work we consider supporting Multi-hop...
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