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Energy efficiency is a growing concern for wireless networks, not only due to the emerging traffic demand from smart devices, but also because of the dependence on the traditional unsustainable energy and the overall environmental concerns. The urgent call for reducing power consumption while meeting system requirements has motivated increasing research efforts on green radio. In this paper, we investigate...
In recent decades, due to limitation of radio spectrum and increasing users in wireless networks, spectral efficiency has been a considerable issue in literatures. In addition, energy consumption is rapidly increasing in wireless communications due to growing demand for wireless technologies especially cellular networks. Therefore, energy efficiency has become an important issue in such networks....
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 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 study, we analyze the role of interleavers in OFDMA system for ensuring uniform BER performance amongst the active users and also investigate their respective PAPR properties. At first considering a generic system in a slowly changing multipath channel where high dispersion in the individual users performance exists, we apply different types of interleaving and show that they in general help...
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...
The implementation of complex signal processing algorithms are required to achieve robust transmission, whereas mobile wireless application require low power dissipation. This paper describes an algorithm and a corresponding hardware architecture for the implementation of OFDMA 802.16e channel estimation. The advantage of the proposed architecture are low power and efficient resource utilization since...
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...
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...
Energy consumption of information and communication industry has generated increasing concerns recently, aiming at reducing power consumption or increasing energy efficiency. This paper proposes an energy efficient hybrid structure which introduces micro sites into traditional OFDMA cellular systems with only central macro base stations (BSs). The deployment of small and low power BSs alongside the...
In this paper, we propose a cross-layer dynamic CQI resource allocation (DCRA) scheme for OFDMA systems. Implemented at the base station (BS) side, DCRA algorithm chooses adaptively the mobile stations (MS) which are to send feedback to maintain their QoS constraints. Based on the channel quality indicator (CQI), feedback rate for each MS is determined exploiting the signaling of MAC layer automatic...
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...
Scheduling is a fundamental component in resource (bandwidth and power) management in NG wireless networks and plays the main role in providing QoS requirements such as delay, throughput and packet loss for different classes of service in 802.16d networks. In this paper we propose a novel scheduling algorithm Strict Priority Based Adaptive modulation and Coding (SP_AMC_Based) that can grantee QoS...
This paper focuses on the problem of queue-aware resource allocation for OFDMA cellular systems supporting both real-time and non-real-time services. A set of practical algorithms is proposed to solve the problem of maximizing the system utility under the constraints of both system resources and the actual amounts of data to be transmitted in buffers. Moreover, an upper bound is devised to quantify...
Multiuser diversity combined with Orthogonal Frequency Division Multiple Access (OFDMA) are a promising technique for achieving high downlink capacities in new generation of cellular and wireless network systems. The total capacity of OFDMA based-system is maximized when each subchannel is assigned to the mobile station with the best channel to noise ratio for that subchannel with power is uniformly...
This paper presents a novel resource allocation procedure for OFDMA downlinks, which stems from an hybridization of the Harmony Search and the Differential Evolution heuristic algorithms. In this setup it is known that optimum subcarrier and power allocation is achieved through 1) assigning each subcarrier to the user with highest channel gain at the given frequency, and 2) a Water-Filling procedure...
In OFDMA, the subcarrier allocation process amongst the users has a significant role in governing the performance of the system. In this paper, we study the application of interleaver based subcarrier allocation schemes for ensuring uniform BER across all the active users. We show that for a slowly changing multipath channel, individual user's BER performance can vary from each other to a great extent,...
In this paper, we propose a channel and queue aware cross-layer algorithm for allocating power and sub-carriers to users in Orthogonal Frequency Division Multiple Access (OFDMA) networks. Our algorithm uses utility to build a bridge between the physical layer and upper layers and also to balance the efficiency and fairness of the radio resource allocation. The objective is to develop a method based...
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 future fourth generation wireless networks OFDM and MIMO techniques will be heavily exploited to provide connectivity to heterogeneous users offering different data traffic types. This paper proposes a low complexity resource allocation strategy for MIMO-OFDMA (Multiple-Input Multiple-Output Orthogonal Frequency Division Multiple Access) broadcast channel to support delay-sensitive traffic with...
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