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Fractional Frequency Reuse (FFR) schemes are frequency allocation techniques used in cellular systems for interference mitigation and enhancing resource utilization. In this paper, analysis is presented comparing FFR and other FR algorithms under realistic network situations. Most implementations in literature considered uniform mobile placements and perfect grid models where well-defined hexagonal...
Fractional frequency reuse (FFR) and soft frequency reuse (SFR) are efficient interference avoidance techniques for emerging OFDMA cellular networks in improving system performance by regularly reusing the frequencies. In this paper, we evaluate the energy efficiency (EE) in bits/J and EE per channel per cell in bits/J/Hz/cell for both the static FFR and SFR systems, in Nakagami-m fading and path-loss...
An interference coordination well suited to OFDMA based wireless network in which cells are divided into special region with various frequency reuse factors, is termed as Fractional Frequency Reuse (FFR). This research focuses on the concept as well working of FFR in Hexagonal geometrical structure for systematic frame work and evaluation. The scheme includes the extensive literature review of both...
We propose the use of relay terminals at the cell edge of an LTE-based cellar system. Each relay terminal is equipped with a 120° directional antenna. We refer to this scheme as the Directional-Relay (DR) scheme. The DR scheme coordinates the inter-cell interference (ICI) stemming from adjacent cells and increases the desired signal level at cell-edge regions. To validate the performance of the DR...
Optimum channel/frequency allocation problem in a general mobile radio networks is well-known to be NP-complete. The optimum general solution for a mobile radio network for even 2-channel case is not known. In this paper, we focus on the case L=2k where L is the number of channels/frequencies and k is a positive integer. In order to minimize the sum of the network level interference, we show that...
Dynamic spectrum access research usually considers very short time-scale secondary access based on spectrum sensing local to the radio. Recent discussion of market mechanisms in civil spectrum management consider longer time-scales of hours and days, still much faster than current processes. We conjecture that many of the benefits of dynamic spectrum management can be realized on a time-scale of minutes...
In this paper, we have discussed the effects of channel interference and evaluated the signal-to-interference plus noise ratio (SINR) for the cognitive radio (CR) network. The cognitive radio is a novel concept of reusing licensed spectrum with unlicensed manner. The most challenging part is the introduction of cognitive radio in the primary user spectrum without causing interference to it. The SINR...
In this paper, we compare the performance attained by several scheduling policies when the resource allocation is performed in a per-user or in a per-frequency resource ordering. We test the capability of both approaches to deal with the quality of service (QoS) provisioning in a multi-service scenario in a mobile OFDMA network. We probe that the comparative performance of these two approaches depends...
This paper reports on a study undertaken by the CEPT SE42 project team, with the objective of deriving regulatory radiation limits which mitigate the impact of adjacent-channel interference from fixed/mobile communication network base stations (BSs) in the 790-862 MHz Digital Dividend spectrum to digital terrestrial television (DTT) services below 790 MHz. A novel stochastic approach for the calculation...
This paper presents a dynamic spectrum sharing algorithm to minimize the inter-cell interference, so as to achieve a high system performance. This algorithm operates in a self-organized manner without the need of any centralized control, thereby is especially useful in local area (LA) where the enhanced-NodeBs (eNB) are close and coordination among them is hard or expensive to achieve. Results show...
Currently International Telecommunications Union (ITU) is working on specifying the system requirements towards the next generation mobile communication systems called International Mobile Telecommunications-Advanced (IMT-A). This paper presents an overview on the technological requirements and current enhancements leading towards IMT-A. The relay nodes, support for higher bandwidth, local area indoor...
In today's high density wireless networks, interference is considered one of the main factors limiting the capacity and increasing the new call blocking probability of a cellular system. In this paper we discuss and analyze a delay scenario in cellular systems and we have proposed a novel handoff management based on cognitive radio scheme to reduce the latency that is caused by the repeated unnecessary...
In this paper we discuss performance results of a novel real-time closed-loop power amplifier (PA) linearization technique that has originally been proposed by Ahmed and Li. The novel approach performs on-the-fly prediction and measurement of the PA AM/AM and AM/PM non-linearity, stores such non-linear characteristics and calculates their inverse functions in order to pre-distort the base-band amplitude...
This paper explores the attributes, layering models and objective functions in cross layer designs for mobile ad hoc wireless networks by taking all the statistical characteristics and constraints from the physical (PHY) layer, media access control (MAC) layer and network (NET) layer into consideration. This paper reviews the entire network optimization across all the PHY/MAC/NET layers. At the PHY...
In this paper, we propose a cognitive radio-based multi-user resource allocation framework for mobile ad hoc networks using multi-carrier DS CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, in addition to potential narrow-band interference, a channel sensing and estimation mechanism is provided...
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