A Comprehensive Survey on Various ICIC Schemes and Proposed 3G RF Interference Mitigation Techniques for OFDM Downlink on Cellular Networks. (original) (raw)
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2013
Fractional Frequency Reuse (FFR) is an efficient method to mitigate Inter Cell Interference in multicellular Orthogonal Frequency Division Multiple Access (OFDMA) systems. In this paper, we analyze the downlink worst case Signal to Interference Ratio for FFR schemes. A closed form expression is derived analytically for the worst SIR, outage probability, and Spectral Efficiency (SE). The proposed analytical technique is used to configure a FFR solution for the downlink of OFDMA cellular system. The analysis is performed using two-tiers cellular network with uniform user density and for three different cases of FFR, namely, Frequency Reuse Factor (FRF) = 3, FRF=4 and sectored FFR. The inner radius configuration depends on equalizing the worst SIR for both inner and outer edges of the cell. Numerical results show that sectored FFR yields the highest SE and low outage probability. Sectored FFR highly balances the needs of interference reduction and resource efficiency.
Fractional frequency reuse and interference suppression for OFDMA networks
2010
Abstract The downlink performance of cellular networks is known to be strongly limited by inter-cell interference. In order to mitigate this interference, a number of frequency reuse schemes have recently been proposed. This paper discusses a novel fractional frequency reuse (FFR) scheme combined with interference suppression for orthogonal frequency division multiple access (OFDMA) networks, which are currently being considered in LTE-A and WiMAX IEEE 802.16 m standardization processes.
Optimal Fractional Frequency Reuse (FFR) and resource allocation in multiuser OFDMA system
2009 International Conference on Information and Communication Technologies, 2009
In this paper we determine the optimal Fractional Frequency Reuse (FFR) and resource allocation in OFDMA system. Since the users at the cell edge are more exposed to inter-cell interference therefore each cell is partitioned into two regions; inner region and outer region. We determine the optimal FFR factor for the outer region, bandwidth assigned to each region and subcarrier and power allocation to all the users in the cell. The problem is formulated as sum-power minimization problem subject to minimum rate constraints in both the regions. This is a mixed linear integer programing problem which is relaxed into a convex optimization problem. We develop an efficient algorithm by using Lagrange dual decomposition theory at reasonable computational cost.
Studying Optimal Design of Strict Fractional Frequency Reuse in OFDMA Cellular System
International Journal of Computer Applications in Technology
The key characteristic of a cellular network is the ability to reuse frequencies to increase both coverage and capacity. Fractional frequency reuse (FFR) is considered to be an efficient inter-cell interference coordination technique well-suited for OFDMA based on wireless communication networks where the cells are partitioned into spatial regions with different frequency reuse factors. In this paper, evaluating strict FFR which represents a type of FFR deployments is presented with four different system models by changing the inner-cell shape for each model. System simulations are used to compare and evaluate the effect of changing the inner-cell shape based on strict FFR performance which performed using dense Monte Carlo simulations. In addition, the effects of some system model parameters are discussed.
Fractional Frequency Reuse (FFR) is an efficient mitigation technique for modern cellular networks because of its low complexity and coordination requirements and resource allocation flexibility. This work considers the use of FFR in the cellular uplink where we analyze the uplink worst case Signal to Interference Ratio (SIR) for two main FFR schemes; which are strict FFR and Soft FFR. A closed form expression is derived analytically for the worst SIR and for the best inner radius. This analytical technique is utilized to configure a FFR solution for the uplink of OFDMA cellular system. The analysis is performed using two-tier cellular network with uniform user density and for three different cases of FFR. The effect of power control exponent on both FFR schemes is also studied. The inner radius configuration depends on equalizing the worst SIR for both inner and outer edges of the cell. Numerical results show that FFR with reuse four yields the highest SIR. It is noticed that power control exponent doesn't affect strict FFR but affects SFR as it reduces its SIR and inner radius.
Fractional Frequency Reuse (FFR) is an efficient interference mitigation technique for modern cellular networks due to its low complexity, low coordination requirements and resource allocation flexibility. This work considers the use of FFR in the cellular uplink where, we analyze the uplink worst case Signal to Interference power Ratio (SIR) for three main FFR schemes strict FFR, Soft FFR, and sectored FFR. A closed form expression is derived analytically for worst SIR and best inner radius. This analytical technique is utilized to configure a FFR solution for the uplink of Orthogonal Frequency Division Multiple Access (OFDMA) cellular systems. The analysis is performed using two-tiers cellular network with uniform user density and for three different cases of FFR, sectored FFR, Soft Frequency Reuse (SFR), and strict FFR, where Frequency Reuse Factor (FRF)= 3, FRF= 4. Also the effect of power control exponent on those FFR schemes is studied. The inner radius configuration depends on equalizing the worst SIR for both inner and outer edges of the cell. Numerical results show that sectored FFR without power control yields the highest SIR followed by strict FFR with FRF= 4 . Power control exponent does not affect FFR with reuse three but strongly affects SFR and FRF= 4 as its increase reduces its SIR and inner radius. Sectored FFR without power control have the highest SE, hence sectored FFR highly balances the needs of interference reduction and resource efficiency but at the expense of increased system complexity.
Interference Control in OFDM-base Mobile Networks
In this paper, we are considering the implementable frequency allocation schemes (in OFDMbase systems as LTE or WiMax) performance, to support maximum capacity and least outage probability. Meantime, techniques combining strategy that called pre-produced code in LTE standard with a frequency allocation scheme, called cell region division, in perspective of interference control, especially in marginal areas of the cell will be considered. Simulation results indicate that rank 1 pre-code scheme base on MISO channel (according to what mentioned in the LTE standard) along with cell region division (to OFDM frequency carriers allocation) lead to the substantial gain in the total network capacity, under the different traffics.
Radio resource allocation for interference management in mobile broadband OFDMA based networks
Wireless Communications and Mobile Computing, 2009
This paper focuses on the inter‐cell interference (ICI) management problem in the downlink channel for mobile broadband wireless OFDMA‐based systems. This subject is addressed from the standpoint of different interrelated resource allocation mechanisms operating in multi‐cell scenarios in order to exploit frequency and multi‐user diversity: ICI coordination/avoidance and adaptive subcarrier and power allocation. Even though these methods can be applied in a stand‐alone way, a significant performance improvement is achieved if they are jointly designed and operate in a combined basis. Several alternatives for mixed frequency and power ICI coordination schemes are proposed in this paper. Connected with a proper power mask‐based design, the potential gain of a flexible frequency sectorization solution, halfway between fractional/soft frequency reuse and pure frequency sectorization, is explored. The main objective is to outperform fractional/soft frequency reuse offering an attractive ...
Abating Inter-Cell Interference in Cellular Network Via FFR Scheme
2015
In cellular network, both the homogeneous and heterogeneous cellular networks there are some problem known as issues. Those issues are concentrated and forwarding steps are taken to overcome the issues. For minimizing the demerits, at each level their performance level is monitored. From certain proposed results, heterogeneous cellular is best for networking. In homogeneous cellular networks, numerical results both upper and lower bounds of optimal BS density are consequential. The heterogeneous cellular networks are revealed as the best type of cellular network in networking. In cellular system, inter-cell interference (ICI) reduces system capacity by aggravating receiving performance of cell edge user. Therefore, to mitigate ICI is very important issue in cellular system. To overcome this ICI problem, fractional frequency reuse (FFR) is introduced. The FFR is performed by separating one cell into three FFR regions and allocates different frequency to each region. By doing this, ea...
Fractional Programming for Communication Systems—Part I: Power Control and Beamforming
IEEE Transactions on Signal Processing, 2018
Fractional programming (FP) refers to a family of optimization problems that involve ratio term(s). This two-part paper explores the use of FP in the design and optimization of communication systems. Part I of this paper focuses on FP theory and on solving continuous problems. The main theoretical contribution is a novel quadratic transform technique for tackling the multiple-ratio concave-convex FP problem-in contrast to conventional FP techniques that mostly can only deal with the single-ratio or the max-min-ratio case. Multiple-ratio FP problems are important for the optimization of communication networks, because system-level design often involves multiple signal-to-interference-plus-noise ratio terms. This paper considers the applications of FP to solving continuous problems in communication system design, particularly for power control, beamforming, and energy efficiency maximization. These application cases illustrate that the proposed quadratic transform can greatly facilitate the optimization involving ratios by recasting the original nonconvex problem as a sequence of convex problems. This FP-based problem reformulation gives rise to an efficient iterative optimization algorithm with provable convergence to a stationary point. The paper further demonstrates close connections between the proposed FP approach and other well-known algorithms in the literature, such as the fixed-point iteration and the weighted minimum mean-square-error beamforming. The optimization of discrete problems is discussed in Part II of this paper.