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In this paper an adaptive resource allocation algorithm in OFDMA based cognitive radio (CR) system is proposed that not only meets the quality of service (QoS) of real-time (RT) services but also increases the dynamic capacity of the system. In contrast to existing algorithms for multi-user OFDM systems which are unable to guarantee maximum sum data rate when applied to CR system in real-time, the...
This paper presents the novel resource allocation scheme for multiclass services in the downlink OFDMA system, in which the frame-based transmission with multiple subchannels and multiple time slots is used. As system utilization and fairness are necessary, the scheme is based on proportional fairness (PF) utility function. Two main service classes are considered. One is the guaranteed service class...
Because of bursty high data rate and delay sensitive nature of high quality multimedia application, the resource allocation in wireless network to meet its quality of service (QoS) has become the most challenging and interesting issue. Orthogonal Frequency Division Multiple Access (OFDMA) employing adaptive channel allocation technique can support these requirement while increasing the system capacity...
In this paper a new prioritization function for Orthogonal Frequency Division Multiple Access (OFDMA) is proposed where the resource allocation problem is divided in two phases, minimum requirements satisfaction, and spectral efficiency maximization. For each phase a different prioritization function is considered. The performance of the proposal is evaluated, via computer simulation, by the packet...
This paper studies the resource allocation problem for the relay-assisted orthogonal frequency-division multiple-access (OFDMA)-based multiuser system. A new transmission protocol, named hierarchicalOFDMA, is proposed to support two-way communications between the base station (BS) and each mobile user (MU) with or without an assisting relay station (RS) in ldquorelayrdquo or ldquodirectrdquo mode,...
Orthogonal frequency division multiple access (OFDMA) is an emerging multiple access technology. In this paper, we focus on the packet scheduling problems of the downlink of OFDMA wireless systems with delay requirements. We revised three different scheduling methods in order to reduce their complexity for practical application based on limited feedback. Furthermore, we simulate these algorithms under...
Adaptive radio resource allocation mechanisms exploiting the inherent frequency selectivity of the wireless medium as well as the multi-user effect are expected to play a key role in emerging next generation OFDMA-based wireless networks. Although a plethora of studies concerning either constant/guaranteed bit rate (CBR/GBR) or variable bit rate/best effort (VBR/BE) traffic has been published to date,...
In this paper, we propose an algorithm for dynamic resource allocation in OFDM (orthogonal frequency division multiplexing) or OFDMA (OFD multiple access) based networks. We consider two groups of users consisting of group 1 called constant bit-rate (CBR) users (who are delay-sensitive and data-rate sensitive) and group 2 called best effort (BE) users. The proposed algorithm gives higher priority...
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