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In order to achieve high performances in data rate and spectral efficiency, Long Term Evolution(LTE) Radio Access Network(RAN) has employed Orthogonal Frequency Division Multiplexing(OFDM) on the physical layer. Due to the characteristics of OFDM, slight differences in frequency offset between an adjacent interferer and a LTE downlink signal leads to totally different impact of interference. This...
In this contribution we present the solution of the utility greedy discrete bit loading for interference limited multicell OFDM networks. Setting the utility as the sum of consumed power proportions, the algorithm follows greedy way to achieve the maximum throughput of the system. Simulation has shown that the proposed algorithm has better performance and lower complexity than the traditional optimal...
In this paper, a quality of service (QoS) based resource allocation for orthogonal frequency division multiplexing (OFDM)-based Cognitive Radio (CR) System with mixed services is proposed. We consider the resource allocation problem for downlink with unoccupied frequency sensed by CR users (CRUs) and total transmission power constraint of the CR base station. In mixed services CR system, the objective...
This paper describes the optimization of the frequency allocation in the downlink of an Orthogonal Frequency Division Multiple Access (OFDMA) cellular network by means of centralized adaptive frequency management. The adaptive frequency allocation is performed off-line based on a Genetic Algorithm (GA) which computes for each cell an optimal number of radio resource blocks as guided by the geometry...
This paper analyzes the performance of Proportional Fair (PF) scheduling in Orthogonal Frequency Division Multiple Access (OFDMA) wireless systems. OFDMA represents a promising multiple access scheme for high-data-rate transmission over wireless channels as it combines the Orthogonal Frequency Division Multiplexing (OFDM) modulation and subcarrier allocation. On the other hand, the PF scheduling is...
Femtocell is one of promising key technologies to increase the efficiency and coverage of next generation broadband wireless networks. However, there exists interference problem between femtocells and macrocell due to co-channel operation. In this paper, we propose an efficient frequency resource allocation scheme for newly deployed femtocells in the legacy OFDMA networks in order to maximize the...
The peak-to-average power ratio (PAPR) of Nyquist filtered broadband single carrier (SC)-FDMA signals can be reduced by increasing the filter roll-off factor α. Furthermore, an additional frequency diversity gain can be obtained by making use of the excess bandwidth introduced by the transmit filtering. However, if the carrier-frequency separation is kept the same as in the case of α=0, the adjacent...
Since the using of OFDM in LTE system eliminates the inter-channel interference within cells, inter-cell interference has become the major influence factor of inter-cell resource allocation. Besides, with the increase of types of traffics, different QoS should be provided for different quality of services. A modified algorithm is proposed to ensure multi-traffic QoS by using rate conversion in allocation...
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...
This paper proposes a new wireless scheduling methodology which takes advantage of future predictions of data rate for the several users competing for physical access. Based on a system which allows low-cost 3D mapping of an environment in real-time, the predictions are obtained via either low-resolution path-loss prediction given the physical structure of the surroundings or by reference to data...
In fourth generation wireless communication standards, the throughput enhancement for cell edge users is a main issue so that various inter-cell interference (ICI) coordination techniques have been suggested. Since the coordination between different cells requires the resources of cooperating cell, its use should be determined carefully. In this paper, we consider two basic handover schemes (Fast...
We define and evaluate the downlink flow-level capacity of a fractionally loaded OFDMA network utilizing round robin (RR) or proportional fair (PF) scheduling. The flow-level capacity is the maximum traffic intensity that can be supported by a sector while satisfying a minimum flow throughput requirement for bursty, elastic traffic. We obtain a simple, insightful capacity expression for RR scheduling;...
This paper presents a technique for using propagation measurements to perform a site-specific technical and economic comparison of indoor and outdoor orthogonal frequency division multiple access (OFDMA) infrastructure. This work is motivated by the fact that fourth generation (4G) network operators have a choice when provisioning a network to serve indoor users. An operator can choose to retrofit...
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...
The adaptive resource allocation will be a key technique of the OFDMA systems in the future wireless networks due to the great improvement of the network throughput. However, in order to allocate the subcarriers and power adaptively, the users need to send back the channel state information (CSI) periodically to the base station. The feedback overhead is huge, and it brings a big burden to the uplink...
The MIMO-OFDM Adaptive MCM System changes MIMO scheme, channel coding rate, and modulation scheme, adaptively, according to the channel conditions. And the addition of Pre-coding and Antenna Subset Selection assures a better performance and higher data rate. The MIMO-OFDM Adaptive MCM System achieves a better average throughput performance than a Non Adaptive-MCM system; as SNR increases, the throughput...
We present high data rate wideband transceiver design and experimental evaluation for 3.62 Gbps wireless transmission systems in this paper. The present system provides high definition moving picture and contents in a real-time wireless environment at home, offices or class rooms of universities. Also, the present platform provides a test platform for the Giga level high throughput wireless communication...
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...
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