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In this paper, we consider a four-node relay-based OFDMA system. The expression of the upper bound for the achievable rate in Successive Relaying (SUR) protocol is derived by using the cut-set theorem for half-duplex systems. Based on this expression, the near-optimal solution of the achievable rate is obtained in the joint power and subcarrier allocation constraint, according to the dual problem...
The opportunistic beamforming (OB) technique in multicellular OFDMA networks is investigated in this paper. For this reason, three cross-layer radio resource management (RRM) algorithms for OFDMA operational scenarios that are based on typical resource allocation targets such as minimization of transmit power, maximization of throughput and interference averaging are considered. The OB concept is...
In this paper, we provide a new resource management algorithm with delay constraints in cognitive OFDMA Systems. Our objective is to give priority to the high real-time cognitive user in the allocation of the channel in the first scheduling slot, maximize multiple cognitive users' weighted rate sum by jointly adjusting their frequency and power resource, under the constraints of multiple primary users'...
This paper analyzes the problem of allocating power and subchannels in the downlink of a multi-cell, full-reuse OFDMA cellular system. We propose a distributed iterative algorithm, in which the allocation is performed independently in each cell, by maximizing the cell rate subject to a power constraint. The algorithm restricts the set of users that can be allocated on each subchannel, in order to...
Efficient Branch-and-Bound (BnB) based radio resource allocation (RRA) algorithms are proposed for Orthogonal Frequency Division Multiple Access (OFDMA) system in this paper. Optimal RRA solution can be obtained by BnB based Algorithm 1 with easy implementation. Suboptimal RRA solution can be achieved by BnB based Algorithm 2 with a large computational complexity reduction. Tradeoff between throughput...
The IEEE 802.16 standards are based on Orthogonal Frequency Division Multiplexing (OFDM) and multi-user OFDM (also known as OFDMA) for their desirable characteristics and potentials. Although well established, these standards only provide a framework of necessary mechanisms for deployable systems. Majority of the resource allocation issues are left unspecified. The conventional one-dimension scheduling...
This paper proposes a novel channel allocation method for multi-cells OFDMA-FDD networks with a reused frequency factor (RFF) of one. The proposed algorithm predicts the co-channel interference (CCI) of active mobile stations (MSs) before allocating suitable subcarriers to a new MS. In order to maintain a desired quality of service (QoS) of the network, only subcarriers having signal-to-interference-plus-noise...
The key issues in the design of a cross-layer optimization scheme for multiuser orthogonal frequency multiple access (OFDMA) systems are the optimal subcarrier, bit and rate distribution policies. In many recent researches, these allocation strategies are derived either through dynamic programming or via mathematical analysis. When the latter option is available, an additional iterative process is...
This paper mainly investigates the problem of radio resource allocation for heterogeneous services transmission in OFDMA-based wireless networks, where the Soft QoS traffics are considered. In communication systems from the users' point of view, utility is a good metric to describe the satisfaction of services, the objective of this paper is to improve the total utility of all the system users, and...
In this paper, a queue aware game theoretic cross-layer scheme is introduced for multiuser orthogonal frequency division multiple access (OFDMA) wireless systems. A joint scheduling process that combines an adaptive modulation (AM) at the physical layer (PHYL) along with a discrete Markov modulated Poisson process (dMMPP) at the medium access control (MAC) layer, is devised. Moreover, relied on this...
In a Multiple Input Multiple Output (MIMO) architecture, self-interference becomes the dominant source of impairment, particularly when correlation exists between spatial sub-channels. This paper aims to minimize the effect of self-interference by means of dynamic subcarrier allocation (DSA) and exploiting the knowledge of spatial sub-channel `quality' evaluated by an ESINR metric. The proposed system...
We consider wireless telecommunications systems with orthogonal frequency bands, where each band is referred to as a channel, e.g., orthogonal frequency-division multiple access (OFDMA). For a given snap-shot in time, two joint channel assignment and power allocation optimization problems are presented, one in downlink and one in uplink. The objective is to maximize the minimum total Shannon capacity...
Cooperative diversity methods are used to increase network throughput while considering fairness. By using these methods in OFDMA relay-enhanced systems, the best transmission link between direct transmission link and decode-and-forward relaying link is selected dynamically. In this paper, we improved the resource allocation algorithms introduced by Wang et. al. by proposing two new decision criteria...
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...
This paper proposes a novel game-theoretic cross-layer design for orthogonal frequency division multiple access (OFDMA) wireless networks, which operates optimal subcarrier, power and rate allocation. Based on the Nash bargaining solution (NBS) and coalitions, the proposed scheme not only maximizes the system's effective data rate but also supports proportional fairness among the users by considering...
Most existing works on resource allocation in cooperative OFDMA systems have focused on homogeneous users with same service and demand. In this paper, we focus on resource allocation in a service differentiated cooperative OFDMA system where each user has individual QoS requirement. We investigate joint power allocation, relay selection and subcarrier assignment to maximize overall system rates with...
In this paper, we investigate resource allocation issue in OFDMA-based decode-and-forward cooperative networks and propose joint subcarrier and power allocation schemes. The optimal solution of this combinable allocation has high computational complexity, so we divide our solution into two steps. The first step is to distribute subcarriers to relays and destination under the assumption of equal power...
Providing ubiquitous very high data rate coverage in next generation wireless networks is a formidable goal, requiring cost-effective radio access network (RAN) devices, such as multi-user enabled amplify- and-forward (AF) relays, and fair radio resource management (RRM). To further this goal, we investigate multi-user enabled AF relays which multiplex user's data in orthogonal frequency division...
The cooperation among cognitive users (CUs) is considered as an efficient means to improve the primary user (PU) sensing in cognitive radio environment. Almost all previous related works employ the cooperation among CUs for PU activity detection whereas in this paper, the notions of cooperation among PUs and CUs are applied. This is achieved by allocating the available PU power among OFDMA subcarriers...
The new mobile wireless metropolitan area network (WMAN) architecture imposes a demanding performance requirement on the radio resource to provide broadband internet access. The radio resource is partitioned as bursts in time and frequency domains and used by mobile stations (MS) in an exclusive manner. The base station (BS) functionally serves as a resource controller for traffic to and from the...
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