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Fractional frequency reuse (FFR) is an interference coordination technique well-suited to OFDMA based wireless networks wherein cells are partitioned into spatial regions with different frequency reuse factors. This work focuses on evaluating the two main types of FFR deployments: Strict FFR and Soft Frequency Reuse (SFR). Relevant metrics are discussed, including outage probability, network throughput,...
We study in the present paper the spectral efficiency of OFDMA cellular networks which is a classical indicator of their performance usually calculated by simulations. On the other hand, due to an increasing interest on the environmental impact of these networks, we study also their energy efficiency which may be defined as the ratio of the spectral efficiency and the consumed energy. We give an explicit...
Performance of next generation OFDM/OFDMA based Distributed Cellular Network (ODCN) where no cooperation based interference management schemes are used, is dependent on four major factors: 1) spectrum reuse factor, 2) number of sectors per site, 3) number of relay station per site and 4) modulation and coding efficiency achievable through link adaptation. The combined effect of these factors on the...
Multi-carrier modulation and especially CP-OFDM is widely used nowadays in several radio communications. However, FBMC is a potential alternative to CP-OFDM since it does not require cyclic prefix, and thus, it has a higher spectral efficiency. One of the characteristics of FBMC is that the received data are accompanied by a two dimensional inter-symbol interference term (2D ISI), which complicates...
In this work, we analyze the performance of a multi-user sectored MIMO/OFDMA system under the limited feedback constraint. Dynamic radio resource management methods are used to a reuse-one sectorized cell in order to reduce the cross-sector interference. Simulation results show that the proposed strategy reduces the co-channel interference and maintain at the same time high spectral efficiency.
FBMC transmission system was proposed as an alternative approach to OFDM system since it has a higher spectral efficiency. One of the characteristics of FBMC is that the demodulated transmitted symbols are accompanied by interference terms caused by the neighboring transmitted data in time and frequency domain. The presence of this interference is an issue for the Maximum Likelihood (ML) implementation...
In current multi-hop relay networks (MRNs), normally the communication path is not optimized, especially when two mobile stations (MSs) attached to the same relay station (RS) need to communicate with each other. In this paper, a novel data transmission scheme: administrable and controllable local forwarding for OFDMA-TDD based two-hop relay cellular networks, is proposed. In the local forwarding...
The next generation 3GPP long-term evolution (LTE) mobile system will use orthogonal frequency division multiplexing access (OFDMA) as the key technology to improve the spectrum efficiency and flexible user resource allocation. One of the challenges of OFDMA systems is the interference at the cell edge where users are likely to get high interference from neighbouring cells. In a network with non-uniform...
Reference symbols (pilots) support coherent detection, but add overhead and consume transmit power. A sophisticated pilot design needs to trade-off the attainable channel estimation accuracy with the induced losses in bandwidth & power efficiency. MIMO transmission, transmit beamforming, and spatial multiplexing further complicate pilot design. In this paper a unified analytical framework is developed...
This paper presents a novel distributed framework to decide the spectrum assignment in a primary cellular radio access network. The distributed nature of the framework allows each cell to autonomously decide (by means of machine learning procedures) the best frequencies to use in order to maximize spectral efficiency, preserve quality-of-service, and generate spectrum gaps, so that secondary cognitive...
This paper explains a system level evaluation framework which allows performance assessment of cellular OFDM- based systems at different carrier frequencies. In the numerical examples we model the downlink transmission of an 3GPP LTE deployment.
Cellular radio systems are often limited due to the presence of cochannel interference. Basically, radio systems may be operated by utilizing asynchronous or synchronous downlink transmission from all base stations in the system, where synchronization between terminals and their serving base station is mandatory in both concepts. We provide a comparison between the theoretical achievable spectral...
Orthogonal frequency division multiplexing offset quadrature amplitude modulation (OFDM/OQAM) is a multi carrier modulation using staggered transmission on the I and Q axes. It uses as well an optimized non-rectangular pulse shaping. There are several advantages with respect to the conventional OFDM modulation, while the main drawback is the intrinsic intersymbol interference, hindering e.g. a proper...
To increase the spectral efficiency of orthogonal frequency division multiplexing (OFDM) systems, many techniques have been proposed. Recently, we proposed a superimposition scheme which is called the time domain superimposition of data (TDSD). In this paper, we compare the performance of TDSD with the conventional superimposition schemes such as the superimposed periodic pilot in the time domain...
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