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In this paper, we formulate an optimization problem for resource allocation and scheduling in orthogonal frequency division multiple access (OFDMA) half-duplex decode-and-forward (DF) relay assisted networks. Our problem formulation takes into account artificial noise generation to combat a multiple antenna eavesdropper. The secrecy data rate, power, and sub-carrier allocation policies are optimized...
In this paper, resource allocation and scheduling in an orthogonal frequency division multiple access (OFDMA) downlink network is studied. The considered problem is modeled as an optimization problem which takes into account a multiple antenna eavesdropper and artificial noise generation for secure communications. Power, secrecy data rate, and subcarrier allocation are optimized for maximization of...
In cooperative wireless communications, beamforming at relays can be employed to increase the signal-to-noise ratio (SNR). Since beamforming at relays requires that channel state information (CSI) be exchanged, an efficient CSI feedback scheme is proposed to reduce the feedback overhead incorporating an optimization of the combining and beamforming weights. With 802.16e OFDMA time-division duplexing...
In this paper we address the challenge of multiuser scheduling in the downlink of 3GPP UMTS/LTE. Long Term Evolution (LTE) imposes the constraint of using the same code rate, modulation order and transmit power for all resources a User Equipment (UE) is scheduled onto. This, in addition to the lack of channel knowledge, prohibits theoretical concepts such as capacity maximization to be applied for...
In this paper, we consider the problem of resource allocation in relay aided uplink multi-user transmission with a single destination node. We adopt the amplify-and-forward (AF) relaying scheme and the orthogonal frequency division multiple access (OFDMA) as the main transmission modulation. The optimization is formulated as maximizing the end-to-end system throughput subject to limited number of...
In this paper we consider the Downlink Beamforming (DLBF) and resource allocation problem in MIMO-OFDMA systems. We consider the sum-power minimization or margin adaptive problem. This is a variable Signal to Interference and Noise Ratio (SINR), non-convex optimization problem and many aspects of this problem are not well understood. By using uplink downlink duality we first obtain the expression...
This paper focuses on the problem of maximizing the system utility for real-time services in OFDMA cellular systems. We evaluate the upper bound for the global maximum of the system utility, whose actual value is very difficult to obtain when the utility functions are not concave. A linear programming based resource allocation algorithm is proposed to approach the bound, and a priority-based resource...
We study a dynamic inter-cell interference coordination scheme formulated using a novel binary integer linear programming optimization technique. The scheme aims to maximize utility, where different utility measures have been defined to model varying levels of user fairness. The formulated problem is decomposed into a number of smaller sub-problems and solved iteratively to ease the computational...
This paper focuses on the adaptive resource allocation strategies for two-hop multiuser OFDMA nonregenerative relay networks considering both maximization of total throughput and fairness constraints among users. First, an optimal resource allocation scheme to maximize the overall data rate is developed with separate transmit power constraints both at source and relay nodes. An alternative scheme...
This paper presents a novel fair scheme for resource sharing between nodes in OFDMA mesh networks. The problem is to maximize the overall system rate, under each user's maximal power and minimum rate constraints. To solve the underlying problem, we propose an approach that combines the merits of the well known Lagrange dual framework and the Lambert-W function. By using the Lambert-W function, resource...
In this paper, we propose a new adaptive subcarrier allocation for a multiuser two-way OFDMA relay network. In the proposed algorithm, subcarriers are allocated to the user-pairs and relays to maximize the achievable sum-rate over all user-pairs while satisfying the minimum rate requirement for each user-pair. Simulation results show that the proposed algorithm improves spectral efficiency and fairness.
In this paper, we study the resource allocation problem in relay aided two-hop uplink multi-user transmission with a single relay node and a single destination node. The orthogonal frequency division multiple access (OFDMA) is adopted as the main transmission modulation. We investigate the problems of subcarrier allocation, subcarrier coupling, and power allocation. The optimization is formulated...
In this paper we focus on the subcarrier allocation for the uplink OFDMA based cooperative relay networks. Multiple cells were considered, each composed of a single base station (destination), multiple amplify and forward (AF) relay stations and multiple subscriber stations (sources). The effects of inter-cell interference (ICI) have been considered to optimize the subcarrier allocation with low complexity...
In this paper we extend the base station (BS) assignment problem to incorporate backhaul related constraints into the assignment decision. This is motivated by the fact that the deployment of more spectral efficient radio access technologies are currently imposing stringent bandwidth requirements at cell sites, and there is a growing concern that backhaul network can become a new network bottleneck...
Multiuser OFDMA is a promising multiaccess technique for serving users with many non-interfering resources. In the present paper, the problem of the optimum power allocation for maximizing the sum rate with total fairness and total power constraints is tackled. If the sum rate would be a priori known, it could be simply distributed uniformly among the users. Then for each user, the minimum required...
In this paper, the problem of wireless resource allocation in OFDMA-based cognitive cooperative network is investigated. The objective is maximizing the throughput of primary users in a system in which cognitive users act as a relay for primary users. In our proposed scheme, while primary users achieved desire rate, they dedicate some subcarrier for cognitive users. We propose two different algorithms...
In this paper, we study the coexistence and optimization of a multicell cognitive radio network (CRN) which is overlaid with a multicell primary radio network (PRN). We propose a PRN-willingness-based design framework for coexistence and subchannel sharing, and a Lagrange duality based technique to optimize the weighted sum rate (WSR) of secondary users (SUs) over multiple cells. First, to avoid unacceptable...
We consider a downlink OFDMA transmission system in which an infrastructure-based relay node is deployed for extending the coverage of a base station. Focusing on decode-and-forward (DF) operation, we study how different relay functionalities affect the system performance. The functionalities include fixed or adaptive subcarrier pairing, information redistribution, buffering, and adjustment of the...
In this paper, we study the sum rate maximization algorithms with long-term proportional rate fairness (PRF) for uplink orthogonal frequency division multiple access (OFDMA) systems. In contrast to the rate-maximization schemes which used short-term PRF in the literature, we propose to use a selective multiuser diversity (SMuD) scheme to achieve a long-term PRF and improved sum rate performance. This...
In this paper, we proposed a heuristic algorithm to investigate the performance of resource allocation combined with coordinated multipoint(CoMP) in multi-cell OFDMA systems. We first develop an analytical model of resource allocation for an arbitrary number of users in the different cells, and formulate it into an optimization problem that is proved to be NP-complete. To reduce the computational...
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