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In this paper, we propose the Nash bargaining solution for the interference problem in cellular networks. The base-stations of neighboring cells negotiate with each other to determine the best number of channels that should be allocated to their edge users. While cells optimize the allocated resources on a local level, the bargaining process acts as a common framework that combines the optimization...
Multi-user MIMO systems have the potential to combine the high capacity achievable with MIMO processing with the benefits of space-division multiple access. Although recent theoretical results show that the sum capacity grows linearly with the minimum of the number of antennas and users, the sum rate of channel inversion does not due to the large spread in the singular values of the channel matrix...
In this paper, we introduce a full-duplex relay (FDR) based on block diagonalization (BD) and analyze the corresponding sum rate in a multiantenna multiuser relay system. The poposed precoding scheme can suppress the self-interference as well as to support multiple users at the same time slot. Simulation results show that the proposed FDR scheme enhances significantly the sum rate performance compared...
The average channel capacity for 3GPP LTE downlink multiuser Multiple Input Multiple Output (MIMO) systems is analyzed in this paper. A packet scheduler is used to exploit the available multiuser diversity in all the three physical domains (i.e., space, time and frequency). A mathematical model is established to derive the channel capacity of multiuser MIMO systems with the frequency domain packet...
In this paper, we present the sum-rate analysis of multiuser multiple-input multiple-output (MIMO) downlink systems with incremental beamforming (IB). We develop the analytical expressions of the ergodic sum-rate for the dual-transmit-antenna scenario. Based on the analytical results, we compare the performance of the proposed IB scheme with popular random beamforming techniques, such as random unitary...
In this paper, a single-carrier frequency domain adaptive antenna array (FDAAA) is proposed for the uplink transmission in cellular systems. The FDAAA algorithm will deal with co-channel interference and exploit the frequency selectivity of the channel fading jointly by using adaptive antenna array in the frequency domain. The receiver of the base station (BS) needs to adjust the AAA weight to optimize...
Interference cancellation (IC) is an effective and easy implemented technology in the multi-user system. Previous studies demonstrate the principles of IC and IC process which show a great improvement in the system capacity with IC. However, no research has focused on the IC system's capacity domain by giving an accurate formula. This article carries on the theoretical analysis of CDMA reverse link...
In this paper, we consider the co-channel interference mitigation capability of fixed relay aided wireless systems, where the relays are linked to the base station using realistic imperfect optical fibre. Three interference mitigation techniques are investigated, namely an appealing reduced-power transmission technique, the classic eigen-beamforming arrangement and their hybrid. The cellular model...
This paper focuses on coordinated scheduling to combat uplink inter-cell interference for LTE/LTE-Advanced. In OFDM system, inter-cell interference is the dominant interference which limits system capacity, especially the performance of cell edge users. Meanwhile inter-cell interference in OFDM system has an inherent characteristic of interference fluctuation, which reduces the efficiency of channel...
Cooperative communication has been recently proposed as a way to improve the performance of wireless communication. However, due to the half duplex constraint, most of the relay networks face a fundamental challenge in terms of multiplexing loss. In this paper, we present an adaptive cooperation via relay selection (ACRS) protocol that improves spectral efficiency. This protocol lets the source transmit...
Robust adaptive multiuser detection schemes are developed for direct-sequence code-division multiple-access (DS-CDMA) multipath frequency-selective fading channels. Multiple access interference (MAI) and intersymbol interference (ISI) are presented in identical format in the expanded signal subspace, which provides convenience for symbol-by-symbol multiuser detection. The proposed multiuse detectors...
The growing energy consumption driven by dramatic increases in the number of users and data usage becomes the key issue for operators in meeting demands on cost reduction and environmental impact targets. Deployment of low power base stations or relay stations in traditional macro cells is expected to reduce the total energy consumption of cellular radio networks. This paper investigates the cell's...
This paper proposes a hybrid cognitive radio (CR) system where underlay and overlay CR approaches are combined. Occasional switches from an overlay CR mode to an underlay CR mode enable to maximize the average throughput of a secondary (unlicensed) network and stable transmission of a secondary user. By controlling switching from an overlay CR mode to an underlay CR mode in a probabilistic sense,...
Smart antennas have received increasing interest due to its capability for improving the performance of wireless radio systems. In this work we studied the throughput maximization in a CDMA 1xEV-DO cellular system when a smart antenna array is implemented. We focus in the downlink of the CDMA cellular system and consider a packet data direct-sequence code division multiple access (DS-CDMA). We show...
Femtocells are expected to increase network capacity, extend macrocell coverage, and introduce new services. Because femtocells share the same frequency band with macrocells in many cases, the femtocell base station (BS) must mitigate the interference with macrocells as well as ensure coverage in customer premises. However, conventional femtocell BS transmit power setting have not adequately accounted...
Inter-cell interference management is one of the most important issues in next generation wireless networks. As opportunistic beamforming induces more fluctuations in the channel, it can be used as an effective means for inter-cell interference management. In this paper, we present a new scheme to decrease inter-cell interference by utilizing the information of user locations along with the inter-base...
The achievable throughput of the entire cellular area is investigated, when employing fractional frequency reuse techniques in conjunction with realistically modelled imperfect optical fibre aided distributed antenna systems (DAS) operating in a multicell scenario. Given a fixed total transmit power, a substantial improvement of the cell-edge area's throughput can be achieved without reducing the...
This paper presents a joint study of several intercell interference coordination strategies considering both static and dynamic approaches, and with different adjustments in their basic parameters. A wide evaluation is presented with special emphasis on the efficiency vs. fairness tradeoff. Besides, additional performance metrics have been considered as enablers of a full understanding of the strengths...
The next generation of wireless networks (e.g., Long Term Evolution (LTE)and WiMAX) use multiple techniques to improve channel spectral efficiencies. In this paper we focus on one such technique, namely Coordinated Beam Switching (CBS). With CBS, each sector determines a sequence of beams (possibly with repetitions) over which it continuously cycles. Each sector independently determines its beam pattern...
In this paper, we study the optimal power allocation of wireless relay nodes which are used in the secondary user (SU) communication of a cognitive radio (CR) network. We consider the behavior of transmitting powers of SUs where those powers are limited to the tolerable interference as seen by the primary user (PU) communication. To improve the performance of the secondary communication based on minimizing...
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