Autonomous Schemes for Inter-cell Interference Coordination in the Downlink of LTE Systems (original) (raw)
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2013 IEEE 24th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2013
Self-adaptation is a key factor for the future evolution of mobile networks due to their increasing complexity and required management efforts. In this paper, we propose an autonomous self-adaptive scheme based on Harmony Search (HS) Algorithm for radio resource management and interference coordination. One of the main strong points of the proposed scheme is that the computations are independent on the number of users and cells in the network. This allows the proposed scheme to adapt to networks of any size and with an arbitrary number of users. The proposed scheme is based on the continuous "selfish" minimization of the violations to the user's rate requirements. Each cell operates individually leading to the decomposition of the complex multi-cell allocation problem into a set of distributed simpler single-cell optimization problems. No apriori frequency planning and/or explicit inter-cell coordination is required. The scheme also achieves a level of altruism by restricting the use of channels satisfying certain rate criterion to allow other cells to utilize them without being affected by interference. Through extensive simulations, we demonstrate that the proposed scheme leads the network to self-adapt into efficient frequency reuse patterns that provides substantial performance improvements to edge users without penalizing other users. We also conducted sensitivity analysis that showed that the values of HS parameters have minimum effect on the scheme performance.
Interference avoidance with dynamic inter-cell coordination for downlink LTE system
2009
The investigation of co-channel interference mitigation techniques (such as, interference cancellation through receiver processing, interference randomization by frequency hopping, and interference avoidance through resource usage restrictions imposed by frequency and power planning) has become a key focus area in achieving dense spectrum reuse in next generation cellular systems such as 3GPP LTE, LTEadvanced, and WiMAX. In this paper, we propose an interference avoidance scheme for LTE downlink that uses dynamic inter-cell coordination facilitated through X2 interface among neighbouring evolved UTRAN nodeBs (eNBs, i.e., LTE base stations). Proposed scheme is evaluated by extensive simulations and compared with a number of reference schemes available in the literature. It has been observed that the proposed scheme attains superior performance in terms of cell-edge and sector throughput compared to those in the reference schemes.
A novel dynamic inter-cell interference coordination technique for LTE networks
2015
Inter-cell interference problems arise in dense frequency reuse networks such as Long Term Evolution (LTE). They have harmful impact on system performance, especially for cell-edge users or users having bad radio conditions. Inter-Cell Interference Coordination (ICIC) schemes aim at mitigating the interference produced by nearby cells to enhance the performance of cell-edge users. ICIC techniques include static frequency reuse schemes and cellcoordinated schemes. In this paper, we propose a semistatic frequency allocation algorithm that exploits evolved-NodeBs communications via X2 interface to mitigate intercell interference. Each cell is divided into two zones: cellcenter and cell-edge. Cell zone satisfaction is tracked, and the unsatisfied zone gets more frequency resource blocks in a distributed manner. The scope of this work is on the downlink of LTE networks using frequency division duplex transmission mode. An LTE downlink system level simulator is chosen to compare the performance of the proposed technique with the frequency reuse-1 model and the fractional frequency reuse technique. Simulation results show that our technique improves throughput cumulative distribution function, achieves a better throughput fairness, and reduces the percentage of unsatisfied users. It is a dynamic technique able to adapt with non-uniform user distributions and traffic demands.
Inter-cell interference coordination based on power control for self-organized 4G systems
2015
Orthogonal Frequency Division Multiplexing (OFDMA) accepted as the multiple access scheme for the 4G Systems provides resistance to inter-symbol and intra-cell interference. However inter-cell interference, when dense frequency reutilization is used, can deteriorate the performance of users with bad channel quality, in particular at cell-edge. Inter-Cell Interference Coordination (ICIC) [1] is a promising mechanism to enhance system performance of 4G. This paper addresses the problem of ICIC in the LTE downlink where the power level selection of resource blocks (RBs) is portrayed as a sub-modular game in the context of self-organizing networks. The existence of Nash equilibriums (NEs) for that type of games shows that stable power allocations can be reached by selfish eNodeBs. To attain these NEs, we propose a semi-distributed algorithm based on a best response algorithm. Based on local knowledge exchanged through the X2 interface in 4G networks [2], each eNodeB will first select a pool of low interference RBs. Then, each eNodeB-to save energy-will make its best to fix the power level on these RBs achieving comparable performances in comparison with a policy serving active users with full power (MAX Power Policy). In order to evaluate our proposal, we compare t he obtained results to an optimal global CoMP (Coordinated Multi-Point) solution where a central controller is the decision maker [3].
2015 7th International Conference on New Technologies, Mobility and Security (NTMS), 2015
Frequency reuse-1 model is required to satisfy the exponential increase of data demands in mobile networks, such as the Long Term Evolution (LTE) of Universal Mobile Terrestrial radio access System (UMTS). However, the simultaneous usage of the same frequency resources in adjacent LTE cells creates inter-cell interference problems, that mainly affect cell-edge users. Inter-Cell Interference Coordination (ICIC) techniques are proposed to avoid the negative impact of interference on system performance. They establish restrictions on resource usage, such as Fractional Frequency Reuse (FFR), and on power allocation such as Soft Frequency Reuse (SFR). In this paper, we classify the existing ICIC techniques, and investigate the performance of reuse-1, reuse-3, FFR, and SFR schemes under various user distributions, and for various network loads. Performance of cell-center and cell-edge users are inspected, as well as the overall spectral efficiency. System level simulations show the advantages and limitations of each of the examined techniques compared to frequency reuse-1 model under different network loads and user distributions, which helps us to determine the most suitable ICIC technique to be used.
2015 IEEE 81st Vehicular Technology Conference (VTC Spring), 2015
One major concern for operators of Long Term Evolution (LTE) networks is mitigating inter-cell interference problems. Inter-Cell Interference Coordination (ICIC) techniques are proposed to reduce performance degradation and to maximize system capacity. It is a joint resource allocation and power allocation problem that aims at controlling the trade-off between resource efficiency and user fairness. Traditional interference mitigation techniques are Fractional Frequency Reuse (FFR) and Soft Frequency Reuse (SFR). FFR statically divides the available spectrum into reuse-1 and reuse-3 portions in order to protect cell-edge users, while SFR reduces downlink transmission power allocated for cell-center resources to protect vulnerable users in the neighboring cells. However, these static techniques are not adapted to non-uniform user distribution scenarios, and they do not provide guarantees on throughput fairness between user equipments. In this paper, we introduce a non-cooperative dynamic ICIC technique that dynamically adjusts resource block allocation according to user demands in each zone. We investigate the impact of this technique on throughput distribution and user fairness under non-uniform user distributions, using an LTE downlink system level simulator. Simulation results show that the proposed technique improves system capacity, and increases throughput fairness in comparison with reuse-1 model, FFR and SFR. It does not require any cooperation between base stations of the LTE network.
Joint scheduling and power control in multi-cell networks for inter-cell interference coordination
2015 IEEE 11th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), 2015
The focus of this paper is targeted towards multicell dense LTE and LTE-Advanced networks, which are composed of multiple evolved Node B (eNodeB) co-existing in the same operating area and sharing the available radio resources. In such scenarios, momentous emphasis is given towards the techniques that take Inter-Cell Interference (ICI) into account while allocating the scarce radio resources. In this context, we propose solutions for the problem of joint power control and scheduling in the framework of Inter-Cell Interference Coordination (ICIC) in the downlink of LTE OFDMA-based multi-cell systems. Two approaches are adopted to allocate system resources in order to achieve high performance: a centralized approach based on convex optimization and a semidistributed approach based on non-cooperative game theory. The centralized approach needs a central controller to optimally allocate resources like in LTE CoMP (Coordinated Multipoint). In the semi-distributed approach, eNodeBs coordinate among each other for efficient resource allocation based on local knowledge conveyed by the X2 interface. It turns out that despite the lower complexity of the semi-distributed approach and its inherent adaptability, there is only a slight discrepancy of results among both approaches, which makes the distributed approach much more promising, in particular as a procedure of SON (Self Organized Network).
Performance of Decentralized Interference Coordination in the LTE Uplink
2009 IEEE 70th Vehicular Technology Conference Fall, 2009
Interference management techniques like inter-cell interference coordination (ICIC) will play a key role in enabling high spectral efficiency in future wireless OFDMA-based cellular systems. The aim of ICIC is to lower inter-cell interference by coordinating the usage of spectrum resources among neighboring cells. Especially for the cell-edge users, avoiding the reuse of the same resources in neighboring cells yields a significant increase in SINR and thus capacity. In this paper, we consider decentralized ICIC schemes for the uplink of an LTE system in which base stations perform selfish resource allocation decisions. System level simulations in a multi-cell scenario show the convergence of the distributed schemes towards Nash equilibria. The mean cell throughput as well as the 5% CDF user throughput are compared to those achieved by frequency reuse 1 and 3 deployments. The simulation results show that the proposed schemes adapt well to varying uniform and especially non-uniform traffic loads.
Macrocells-User Protected Interference-Aware Transmit Power Control for LTE-A Heterogeneous Networks
Mobile Information Systems, 2016
In Long Term Evolution-Advanced (LTE-A) heterogeneous networks (HetNets), small cells are deployed within the coverage area of macrocells having 1 : 1 frequency reuse. The coexistence of small cells and a macrocell in the same frequency band poses cross-tier interference which causes outage for macrocells users and/or small cell users. To address this problem, in this paper, we propose two algorithms that consider the received interference level at the evolved NodeB (eNB) while allocating transmit power to the users. In the proposed algorithm, the transmit power of all users is updated according to the target and instantaneous signal-to-noise-plus-interference ratio (SINR) condition as long as the effective received interference at the serving eNB is below the given threshold. Otherwise, if the effective received interference at the eNB is greater than the threshold, the transmit power of small cell users is gradually reduced in order to guarantee the target SINR for all macrocells ...
IEEE Transactions on Wireless Communications, 2010
Interference management has been a key concept for designing future high data-rate wireless systems that are required to employ dense reuse of spectrum. Static or semistatic interference coordination based schemes provide enhanced cell-edge performance but with severe penalty to the overall cell throughput. Furthermore, static resource planning makes these schemes unsuitable for applications in which frequency planning is difficult, such as femtocell networks. In this paper, we present a novel dynamic interference avoidance scheme that makes use of inter-cell coordination in order to prevent excessive inter-cell interference, especially for cell or sector edge users that are most affected by inter-cell interference, with minimal or no impact on the network throughput. The proposed scheme is comprised of a two-level algorithm -one at the base station level and the other at a central controller to which a group of neighboring base stations are connected. Simulation results show that the proposed scheme outperforms the reference schemes, in which either coordination is not employed (reuse of 1) or employed in a static manner (reuse of 3 and fractional frequency reuse), in terms of cell edge throughput with a minimal impact on the network throughput and with some increase in complexity.