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This paper presents a cluster based resource allocation scheme for allocating physical resource blocks (PRBs) in downlink of OFDMA based cellular systems. The proposed scheme includes two phases of clustering and sum rate maximization. In the first phase users are clustered by using an interference graph in a way that users in each cluster are allocated the same PRB. This interference graph helps...
In this paper, we consider the group oriented beamforming taking into account the quality of service (QoS) requirement for multimedia applications in multiuser/multi-rate OFDM system. The aim of this paper is to find the scheme for maximizing the system throughput while guarantee the QoS requirements and fairness for all services. The simulation result indicates that this scheme proposed in this paper...
We investigate the network utility maximization (NUM) problem when layered modulation is used at the physical layer of a downlink wireless system. The key idea is to transmit to more than one users with favorable and unfavorable channel qualities at the same time by employing hierarchical constellations. We demonstrate that average throughput of users with unfavorable channel conditions are significantly...
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...
The creation of Ultra-Wideband (UWB) radio platform has allowed the development of high bit-rate Wireless-USB offering High Definition video streaming. Quadrature Phase Shift Keying (QPSK) and Dual Carrier Modulation (DCM) are the current modulation schemes used for Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) in the ECMA-368 defined UWB radio platform. ECMA-368 offers up to 480...
In this paper we consider two alternate packet structures for estimating the multi-input multi-output (MIMO) powerline channel and their impact on achievable application throughputs. In the first packet structure, an orthogonal pair of OFDM symbols is used to estimate the channel. When compared to single-input single-output (SISO) transmissions that use one OFDM symbol to estimate the channel, there...
In underwater acoustic sensor networks, the solution to augment sensor nodes' life time is crucial due to the difficulties in retrieving discharged sensor nodes. Thus, many energy efficient MAC protocols have employed mainly logical ways, such as sleep mode, hand-shaking signaling between nodes, and scheduling of transmission time, rarely using the physical characteristics of underwater acoustic channels...
We consider a random scheduling problem for OFDMA-based indoor PLC systems with time- and frequency-varying channel conditions in a multiuser context. In multichannel systems, opportunistic scheduling can exploit multiuser diversity in both time and frequency domains to improve the system performance. On the other hand, designing a scheduling scheme that simultaneously attains high performance and...
With the HPAV specification, windowed OFDM is now the most commonly used modulation technique in PLC networks. However, another modulation, named OFDM/OQAM, could notably improve the capacity of these networks. Imposing an orthogonality condition only in the real field, this modulation offers a great flexibility in the design of the prototype filter that shapes its symbols. Nevertheless, to take advantage...
We present a prediction-based resource allocation algorithm (RA) for OFDMA downlink over mobile wireless channels, where prediction errors are incorporated in the problem formulation. A solution based on the empirical characterization of the prediction error is proposed. We test the proposed scheme on a realistic scenario using a practical low complexity channel predictor, suitable for implementation...
In this paper we analyze the performance of advanced OFDM packet scheduling techniques based on 3GPP UTRAN Long Term Evolution (LTE) framework for high velocity scenarios. Based on our previous investigations in system performance analysis, we demonstrate that packet scheduler being part of the whole radio resource management (RRM) process has a major impact on it. On the other hand high user velocities...
OFDMA femtocells are generally accepted as a very promising solution for indoor coverage with high data rate. However, the lack of systematic schemes to effectively mitigate macro/femtocell hierarchical interference, fully utilize radio resources, provide quality-of-service (QoS) and fairness guarantee among users suffocate the performance realization of femtocells. In this paper, an Adapted Soft...
This paper presents results from a novel OFDMA multi-cell mobile broadband system level simulator. The tool is used to statistically characterize uplink and downlink inter-cell interference. Without suitable interference management, multi-billion dollar networks can collapse under the strain of heavy traffic loads. Fully loaded interference studies cannot be performed on the network until it has been...
In this paper, we investigate the utility-based resource allocation problem in OFDMA relay networks with service differentiation, where Rate Constraint (RC) and Best Effort (BE) services are supported. Our objective of resource allocation is to maximize the sum utility of BE service users, while guaranteeing that the utility of each RC service user is equal to one. A joint optimization problem for...
MIMO, OFDMA and cooperative relaying are the key technologies in future wireless communication systems. However, under the usage of these technologies, resource allocation becomes a more crucial and challenging task. In multi-user MIMO-OFDMA relay-enhanced cellular networks, we formulate the optimal instantaneous resource allocation problem including user group selection, path selection, power allocation,...
The femtocell deployment in 3GPP/LTE sets new challenges to interference mitigation techniques and Radio Resource Management (RRM). Traditional schemes are mainly designed for classical cellular networks while the ad hoc nature of femtocells notably limits the complexity of possible algorithms. Thus, efficient RRM schemes are essential for limiting the interference impact on end-user performance....
Hybrid subcarrier exclusivity and sharing (HSEnS) scheme with optimized bit loading in uplink multicell OFDMA system is proposed in this paper. Optimizing bit loading under subcarrier exclusivity (SE) and subcarrier sharing (SS) schemes in two adjacent cells is analyzed. Bit loading criteria and boundary setting procedures for convex optimizing bit loading under SS scheme are proposed. And bit loading...
In this paper, we study how the downlink received signal quality and throughput will be affected by deploying the Open Subscriber Group (OSG) Femtocell [1] using Location-Dependent Power Setting (LDPS) scheme with spectrum allocation (1, 3, 3) in the next generation mobile network. The LDPS scheme aims to use a suitable power for femtocell base station to maintains its indoor user coverage. The design...
Radio resource management (RRM) is widely regarded as a critical component in improving spectral efficiency of beyond third generation (3G) cellular air interfaces. Much of the published work in Orthogonal Frequency Division Multiplexing (OFDM) RRM focuses on exploiting multi-user, multi-channel and multi-application diversity. In this paper, we propose a Quality of Service (QoS)-aware bit scheduling...
A game theoretic resource allocation approach is proposed in this paper to distribute the channels in multiuser orthogonal frequency division multiplexing access (OFDMA) relay system. The goal is to maximize the system throughput while considering the fairness of the users. The basic idea is to consider backhaul link and access link together as a bundle. Nash bargaining solution (NBS) is used to distribute...
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