Dissertations / Theses: 'Inter-cell interference'

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Yassin, Mohamad. "Inter-cell interference coordination in wireless networks." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S106/document.

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Grâce aux avancées technologiques dans le domaine des réseaux cellulaires et des équipements mobiles, le nombre d'applications multimédia à haut débit dans les réseaux mobiles ne cesse d'augmenter. On prévoit que le trafic de données dans les réseaux mobiles en 2017 sera 13 fois plus important que celui en 2012. Pour satisfaire aux besoins des équipements mobiles, de nouvelles approches pour la gestion des ressources radio et des puissances de transmission sont requises.Dans le cadre de cette thèse, on s'intéresse à proposer des solutions pour remédier aux problèmes des interférences intercellulaires dans les réseaux mobiles de dernière génération. Nous enquêtons d'une manière exhaustive les différentes techniques de coordination des interférences intercellulaires existantes. Ces techniques sont qualitativement comparées, puis classées selon le taux de coopération requis entre les différentes stations de base, mais aussi selon leurs principes de fonctionnement. Nous abordons également le problème multicellulaire d'allocation des ressources et des puissances de transmission d'une manière centralisée. Nous formulons ce problème d'optimisation centralisé, puis nous le décomposons en deux sous-problèmes indépendants : l'allocation de ressources et l'allocation des puissances de transmission. De plus, une approche distribuée basée sur la théorie des jeux est proposée pour l'allocation des puissances de transmission. Les techniques centralisées de minimisation des interférences intercellulaires offrent la solution optimale au prix d'une grande charge de signalisation. Par contre, les solutions décentralisées réduisent le trafic de signalisation sans garantir l'optimalité de la solution obtenue. Nous proposons ensuite une heuristique de contrôle de puissance qui modifie localement l'allocation des puissances de transmission de manière à éviter le gaspillage d'énergie et pour réduire les interférences ressenties par les utilisateurs des stations de base voisines. Nous proposons également une technique autonome qui gère la distribution des ressources radio entre les différentes zones de chaque cellule. Cette technique répond aux besoins des utilisateurs dans chaque zone en adaptant la distribution des ressources d'une manière dynamique. Nous abordons aussi le compromis entre les techniques de gestion d'interférences intercellulaires centralisées et décentralisées. Nous proposons une approche hybride où l'allocation des ressources radio et des puissances de transmission est faite d'une manière coopérative entre les différentes cellules. Dans un premier lieu, les cellules voisines collaborent afin d'ajuster les puissances de transmission allouées aux ressources radio. Ensuite, la distribution des ressources entre les différentes zones de chaque cellule est modifiée localement, selon les besoins des utilisateurs dans chaque zone
The exponentially increasing demand for mobile broadband communications have led to the dense deployment of cellular networks with aggressive frequency reuse patterns. The future Fifth Generation (5G) networks are expected to overcome capacity and throughput challenges by adopting a multi-tier architecture where several low-power Base Stations (BSs) are deployed within the coverage area of the macro cell. However, Inter-Cell Interference (ICI) caused by the simultaneous usage of the same spectrum in different cells, creates severe problems. ICI reduces system throughput and network capacity, and has a negative impact on cell-edge User Equipment (UE) performance. Therefore, Inter-Cell Interference Coordination (ICIC) techniques are required to mitigate the impact of ICI on system performance. In this thesis, we address the resource and power allocation problem in multiuser Orthogonal Frequency Division Multiple Access (OFDMA) networks such as LTE/LTE-A networks and dense small cell networks. We start by overviewing the state-of-the-art schemes, and provide an exhaustive classification of the existing ICIC approaches. This qualitative classification is followed by a quantitative investigation of several interference mitigation techniques. Then, we formulate a centralized multi-cell joint resource and power allocation problem, and prove that this problem is separable into two independent convex optimization problems. The objective function of the formulated problem consists in maximizing system throughput while guaranteeing throughput fairness between UEs. ICI is taken into account, and resource and power allocation is managed accordingly in a centralized manner. Furthermore, we introduce a decentralized game-theoretical method to solve the power allocation problem without the need to exchange signaling messages between the different cells. We also propose a decentralized heuristic power control algorithm based on the received Channel Quality Indication (CQI) feedbacks. The intuition behind this algorithm is to avoid power wastage for UEs that are close to the serving cell, and reducing ICI for UEs in the neighboring cells. An autonomous ICIC scheme that aims at satisfying throughput demands in each cell zone is also introduced. The obtained results show that this technique improves UE throughput fairness, and it reduces the percentage of unsatisfied UEs without generating additional signaling messages. Lastly, we provide a hybrid ICIC scheme as a compromise between the centralized and the decentralized approaches. For a cluster of adjacent cells, resource and power allocation decisions are made in a collaborative manner. First, the transmission power is adjusted after receiving the necessary information from the neighboring cells. Second, resource allocation between cell zones is locally modified, according to throughput demands in each zone

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Zhang, Sina. "Inter-cell Interference Coordination in Indoor LTE Systems." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91849.

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Inter-cell interference coordination in 3GPP Long Term Evolution system received much attention in recent years. However, most of the studies are based on ideal system with regular hexagon-shaped cell. The indoor environment has special characteristics that the building shape and BS locations are irregular; the traffic load has great variation compared to urban and rural area. So, conventional ICIC scheme may not be used in indoor situation directly. In this thesis, ICIC scheme is employed for indoor environment. Based on different quality of backhaul, static and dynamic schemes will be proposed. The performances of proposed schemes and the performance of system without ICIC will be simulated and compared. At last, how much the improvement of the system can acquire after applying ICIC schemes will be analyzed, and the question about whether it is good to apply ICIC scheme in indoor environment will be answered.

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Kosta, Chrysovalantis. "Inter-cell interference coordination in multi-cellular networks." Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606702.

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OFDMA is accepted as the most appropriate air-interface for 4G OFDMA based systems by both researchers in industry and academia. A major problem that arises in OFDMA based systems is inter-cell interference that stems from aggressive frequency reuse and is particularly worse in cell-edge areas. Therefore, Inter-Cell Interference Coordination (ICIC) has been proposed as a promising method to mitigate inter-cell interference (ICI) mainly in the overlapping (cell-edge) areas of a multi-cell cellular network. The main objectives of this thesis are to investigate inter-cell interference in a heterogeneous system comprising of both macro and femto cells, propose and evaluate less complex novel inter-cell interference coordination/avoidance techniques that increase both cell-edge throughput and overall cell throughput. Initially, our scenario focuses on the investigation of co-channel interference in macrocell deployments. In this direction, we propose a static ICIC technique for OFDMA macrocell networks based on cyclic difference sets a branch of combinatorial mathematics to minimize the inter-cell interference. Then, we formulate the dynamic ICIC problem in a linear way in order to minimize the complexity issues with the scalability of the problem. We show that with minimal loss of optimality, this linear problem can be simplified into two smaller problems i.e. the multi-user scheduling (base station) problem and the multi-cell scheduling (network) problem. Simulation results confirm the increased effectiveness of proposed ICIC schemes in both metrics (i.e. cell-edge and total cell throughput) over a number of state-of-the-art (static and dynamic) interference avoidance schemes. After, the ICIC technique is optimized to minimize the total transmit power by employing inter-cell and intra-cell power control without compromising the cell-edge throughput. Here, we formulate the multi-objective problem as a multi-dimensional knapsack problem. Our simulation results of the proposed scheme show its increased energy efficiency and user fairness compared with the state-of-the-art energy efficient schemes. Finally, the complexity of the ICIC problem and the need of a centralised controller are further reduced in order to benefit small-cell deployments. Here, it is shown that the complexity of the ICIC version can be further reduced by employing a dual decomposition method from optimization theory. Extensive simulation results show a significant improvement of the proposed scheme compared with some distributed reference schemes in terms of cell-edge and total cell throughput and thus it is a promising candidate for next generation mobile systems.

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Vincenzi, Lorenzo. "Inter-cell Interference Coordination algorithms for 5G networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25332/.

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L'elaborato affronta il tema dell'Inter-Cell Interference Coordination (ICIC) applicato ad un sistema 5G. Il sistema viene modellato mediante il software di simulazione ns-3. L'approccio utilizzato è quello di unire gli algoritmi di Frequency Reuse, che rappresentano un approccio statico di coordinamento dell'interferenza inter-cella, e il beamforming, caratteristica fondamentale introdotta dallo standard 5G, allo scopo di ottimizzare l'allocazione di risorse verso tutti gli utenti che il sistema cellulare copre. Lo studio effettuato affronta in maniera sistematica le specifiche dello standard 5G, con una particolare attenzione al modo in cui questo viene implementato all'interno del software di simulazione, con lo scopo di attuare modifiche in maniera consapevole delle caratteristiche che lo standard presenta. Infatti, proprio perché lo scenario di partenza non comprende l'applicazione di algoritmi di ICIC, è stato necessario modificare l'architettura iniziale della network già impostata all'interno di ns-3 e realizzare un interfacciamento con gli algoritmi di Frequency Reuse, andando a modificare il modo in cui la Base Station alloca le risorse. Inoltre, è stato necessario introdurre tutta la componente di segnali che utenti e Base Station si scambiano per fornirsi informazioni utili al coordinamento dell'interferenza inter-cella. In particolare, mediante il software viene modellato uno scenario di partenza, rappresentato da un generico stadio, e vengono valutate le performance del sistema in termini di pacchetti ricevuti sui totali pacchetti trasmessi. Con l'applicazione di un coordinamento dell'interferenza tra le celle si raggiungono risultati significativi, che portano ad un incremento delle performance del sistema. Il risultato finale mostra come l'utilizzo di algoritmi di ICIC migliori le performance del sistema grazie alla riduzione dell'interferenza, che permette un'allocazione di maggiori risorse con una perdita di pacchetti significativamente ridotta.

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Gunning, Dan, and Pontus Jernberg. "Estimation of Inter-Cell Interference in 3G Communication Systems." Thesis, Linköpings universitet, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71156.

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In this thesis the telecommunication problem known as inter-cell interference is examined. Inter-cell interference originates from users in neighboring cells and affects the users in the own cell. The reason that inter-cell interference is interesting to study is that it affects the maximum data-rates achievable in the 3G network. By knowing the inter-cell interference, higher data-rates can be scheduled without risking cell-instability. An expression for the coupling between cells is derived using basic physical principles. Using the expression for the coupling factors a nonlinear model describing the inter-cell interference is developed from the model of the power control loop commonly used in the base stations. The expression describing the coupling factors depends on the positions of users which are unknown. A quasi decentralized method for estimating the coupling factors using measurements of the total interference power is presented. The estimation results presented in this thesis could probably be improved by using a more advanced nonlinear filter, such as a particle filter or an Extended Kalman filter, for the estimation. Different expressions describing the coupling factors could also be considered to improve the result.

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Afolalu, Oladele Felix. "Inter-cell interference coordination in 5G ultra-dense networks." Doctoral thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33607.

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The exponentially increasing demand for mobile broadband communications has led to the dense deployment of cellular networks with aggressive frequency reuse patterns. The future Fifth Generation (5G) networks are expected to overcome capacity and throughput challenges by adopting a multi-tier architecture where several low-power Base Stations (BSs) are deployed within the coverage area of the macro cell. Hence, Inter-Cell Interference (ICI) caused by the simultaneous usage of the same spectrum in different cells creates severe problems. ICI reduces system throughput and network capacity, and has a negative impact on cell-edge users and overall system performance. Therefore, effective interference coordination techniques are required, especially, for user-to-cell association and resource allocation to mitigate severe impact of ICI on system performance in 5G heterogeneous networks (HetNets). This is to improve Quality of Service (QoS) and maximize system throughput arising from the deployment of small cell overlay on macro BSs in heterogeneous cellular networks, which creates traffic load imbalance due to varying transmit power of different BSs in the downlink. In this research, a cell association scheme based on Cell Range Expansion (CRE), integrated with power control techniques is proposed. Simulation results are presented to show the ability of this technique to protect offloaded users from severe ICI and maximize throughput while achieving desirable QoS and load balancing for users of different tiers. With the advancement of information and computer technology, the envisioned 5G wireless communication is expected to encompass an unprecedented heterogeneous and ultra-dense communication environment. Vehicular communications play a vital role in 5G wireless network and have been widely studied recently due to its great potential to ensure reliability and support intelligent transportation and various safety applications. This research therefore exploits the tractability of stochastic geometry to analyze the coverage of urban vehicular networks, by deriving a closed-form expression to maximize the ergodic capacity of cellular users (CUEs) and mitigate interference, taking into consideration the QoS requirements of both vehicle-to-vehicle (V2V) and vehicleto-infrastructure (V2I) links. Consequently, the latency and reliability requirements of V2V/V2I links are formulated as optimization constraints, involving joint power allocation and spectrum sharing (PASS), taking into account the slow varying and large scale channel state information (CSI) measurements. Due to non-convex nature of the problem, the optimization is transformed into sub-optimal convex equivalence, while a low complexity Algorithm that yields optimal resource allocation is then designed to solve it. Simulation results are used to show enhanced performance in our approach compared to related works. Finally, the upsurge in the number of connected devices, such as smart cars, to the envisioned 5G technology is expected to pose high capacity and data rate demands on the network. The conventional access techniques (i.e., CDMA, TDMA and OFDMA) may not meet stringent requirements, such as ultra-low latency, high reliability, improved spectral efficiency and massive device connectivity. This work further investigates non-orthogonal multiple access (NOMA) technique as promising solution to improve spectral efficiency and reduce interference in 5G Ultra Dense Network (UDN). The NOMA scheme is combined with two promising capacity and bandwidth enhancement techniques - massive multiple input and multiple output (MIMO) and carrier aggregation (CA), for overall network performance. In particular, for the proposed novel NOMA-CA approach, we justify the importance of maintaining green communication as a key requirement for 5G with Energy Efficiency (EE) analysis. Firstly, a proportional fairness scheduler is used to perform resource allocation and maintain fairness among users based on their channel condition. Secondly, an optimization problem to maximize the EE weighted-sum under joint power and bandwidth allocation on each aggregated component carrier (CC) is formulated. Conventionally, the formulated optimization is transformed from non-convex to convex problem. An iteratively adaptive Algorithm is then developed to find optimal solution for the problem. Simulation results show better improvement in EE and sum rate compared to the traditional OMA scheme.

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Pateromichelakis, Emmanouil. "Inter-cell interference-aware radio resource management for femtocell networks." Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600130.

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The widespread data demand in emerging wireless cellular technologies necessitates the evolution of traditional networks' deployment to accommodate the ever increasing coverage and capacity requirements. In emerging wireless systems a hierarchical multi-level network that consists of a mixture of outdoor small cells (relays) and indoor small cells (femtocell) deployments underneath the traditional macro-cell architecture can be seen as a key deployment strategy to meet these growing capacity demands. In such networks, Femtocell technology has attracted much attention as a key "player" to address coverage and capacity issues mainly in home and enterprise environments. However, a major challenge that arises in such indoor networks originates from the inter-cell interference between the femtocells (commonly known as co-tier interference), assuming that femtocells share the same spectrum. The main objectives of this thesis are to investigate inter-cell interference in femtocell networks and to propose efficient multi-cell scheduling mechanisms that can mitigate inter-cell interference in dense femtocell environments while maintaining spectral efficiency at acceptable level across the cells. We begin with investigating the impact of co-tier interference in femtocells, highlighting the necessity of interference mitigation mechanisms for arbitrary deployment of femtocells. In this direction. a novel low-complex.ity graph-coloring based interference coordination mechanism is proposed to be applied on top of intra-cell radio resource management. We additionally propose two locally centralized multi-cell scheduling frameworks that enclose adaptive graph-panitioning and weighted capacity maximization concepts. In particular, we decompose the problem in the latter case based on the Exact Generalized Travelling Salesman Problem as a close match in graph-based solutions. Extensive evaluation is provided by simulations showing a significant improvement over the state-of-the-art multi-cell scheduling benchmarks in terms of outage probability as well as user and cell throughput and thus the proposed algorithms are promising candidates of multi-cell scheduling in next generation small cell networks.

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Kurda, Reben. "Cooperation strategies for inter-cell interference mitigation in OFDMA systems." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112032/document.

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Récemment, l'utilisation des réseaux cellulaires a radicalement changé avec l’émergence de la quatrième génération (4G) de systèmes de télécommunications mobiles LTE/LTE-A (Long Term Evolution-Advanced). Les réseaux de générations précédentes (3G), initialement conçus pour le transport de la voix et les données à faible et moyen débits, ont du mal à faire face à l’augmentation accrue du trafic de données multimédia tout en répondant à leurs fortes exigences et contraintes en termes de qualité de service (QdS). Pour mieux répondre à ces besoins, les réseaux 4G ont introduit le paradigme des Réseaux Hétérogènes (HetNet).Les réseaux HetNet introduisent une nouvelle notion d’hétérogénéité pour les réseaux cellulaires en introduisant le concept des smalls cells (petites cellules) qui met en place des antennes à faible puissance d’émission. Ainsi, le réseau est composé de plusieurs couches (tiers) qui se chevauchent incluant la couverture traditionnelle macro-cellulaire, les pico-cellules, les femto-cellules, et les relais. Outre les améliorations des couvertures radio en environnements intérieurs, les smalls cells permettent d’augmenter la capacité du système par une meilleure utilisation du spectre et en rapprochant l’utilisateur de son point d’accès au réseau. Une des conséquences directes de cette densification cellulaire est l’interférence générée entre les différentes cellules des diverses couches quand ces dernières réutilisent les mêmes fréquences. Aussi, la définition de solutions efficaces de gestion des interférences dans ce type de systèmes constitue un de leurs défis majeurs. Cette thèse s’intéresse au problème de gestion des interférences dans les systèmes hétérogènes LTE-A. Notre objectif est d’apporter des solutions efficaces et originales au problème d’interférence dans ce contexte via des mécanismes d’ajustement de puissance des petites cellules. Nous avons pour cela distingués deux cas d’étude à savoir un déploiement à deux couches macro-femtocellules et macro-picocellules. Dans la première partie dédiée à un déploiement femtocellule et macrocellule, nous concevons une stratégie d'ajustement de puissance des femtocellules assisté par la macrocellule et qui prend en compte les performances des utilisateurs des femtocells tout en atténuant l'interférence causée aux utilisateurs des macrocellules sur leurs liens montants. Cette solution offre l’avantage de la prise en compte de paramètres contextuels locaux aux femtocellules (tels que le nombre d’utilisateurs en situation de outage) tout en considérant des scénarios de mobilité réalistes. Nous avons montré par simulation que les interférences sur les utilisateurs des macrocellules sont sensiblement réduites et que les femtocellules sont en mesure de dynamiquement ajuster leur puissance d'émission pour atteindre les objectifs fixés en termes d’équilibre entre performance des utilisateurs des macrocellules et celle de leurs propres utilisateurs. Dans la seconde partie de la thèse, nous considérons le déploiement de picocellules sous l'égide de la macrocellule. Nous nous sommes intéressés ici aux solutions d’extension de l’aire picocellulaire qui permettent une meilleure association utilisateur/cellule permettant de réduire l’interférence mais aussi offrir une meilleure efficacité spectrale. Nous proposons donc une approche basée sur un modèle de prédiction de la mobilité des utilisateurs qui permet de mieux ajuster la proportion de bande passante à partager entre la macrocellule et la picocellule en fonction de la durée de séjour estimée de ces utilisateurs ainsi que de leur demandes en bande passante. Notre solution a permis d’offrir un bon compromis entre les débits réalisables de la Macro et des picocellules
Recently the use of modern cellular networks has drastically changed with the emerging Long Term Evolution Advanced (LTE-A) technology. Homogeneous networks which were initially designed for voice-centric and low data rates face unprecedented challenges for meeting the increasing traffic demands of high data-driven applications and their important quality of service requirements. Therefore, these networks are moving towards the so called Heterogeneous Networks (HetNets). HetNets represent a new paradigm for cellular networks as their nodes have different characteristics such as transmission power and radio frequency coverage area. Consequently, a HetNet shows completely different interference characteristics compared to homogeneous deployment and attention must be paid to these disparities when different tiers are collocated together. This is mostly due to the potential spectrum frequency reuse by the involved tiers in the HetNets. Hence, efficient inter-cell interference mitigation solutions in co-channel deployments of HetNets remain a challenge for both industry and academic researchers. This thesis focuses on LTE-A HetNet systems which are based on Orthogonal Frequency Division Multiplexing Access (OFDMA) modulation. Our aim is to investigate the aggressive interference issue that appears when different types of base stations are jointly deployed together and especially in two cases, namely Macro-Femtocells and Macro-Picocells co-existence. We propose new practical power adjustment solutions for managing inter-cell interference dynamically for both cases. In the first part dedicated to Femtocells and Macrocell coexistence, we design a MBS-assisted femtocell power adjustment strategy which takes into account femtocells users performance while mitigating the inter-cell interference on victim macrocell users. Further, we propose a new cooperative and context-aware interference mitigation method which is derived for realistic scenarios involving mobility of users and their varying locations. We proved numerically that the Femtocells are able to maintain their interference under a desirable threshold by adjusting their transmission power. Our strategies provide an efficient means for achieving the desired level of macrocell/femtocell throughput trade-off. In the second part of the studies where Picocells are deployed under the umbrella of the Macrocell, we paid a special attention and efforts to the interference management in the situation where Picocells are configured to set up a cell range expansion. We suggest a MBS-assisted collaborative scheme powered by an analytical model to predict the mobility of Macrocell users passing through the cell range expansion area of the picocell. Our goal is to adapt the muting ratio ruling the frequency resource partitioning between both tiers according to the mobility behavior of the range-expanded users, thereby providing an efficient trade-off between Macrocell and Picocell achievable throughputs

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Al-Aaloosi, A. B. A. "Inter-cell interference mitigation in LTE-advanced heterogeneous mobile networks." Thesis, University of Salford, 2017. http://usir.salford.ac.uk/44581/.

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Heterogeneous Networks are one of the most effective solutions for enhancing the network performance of mobile systems, by deploying small cells within the coverage of the ordinary Macro cells. The goals of deploying such networks are to offload data from the possibly congested Macro cells towards the small cells and to achieve enhancements for outdoor/ indoor coverage in a cost-effective way. Moreover, heterogeneous networks aim to maximise the system capacity and to provide lower interference by reducing the distance between the transmitter and the receiver. However, inter-cell interference is a major technical challenge in heterogeneous networks, which mainly affects system performance and may cause a significant degradation in network throughput (especially for the edge users) in co-channel deployment. So, to overcome the aforementioned problem, both researchers and telecommunication operators are required to develop effective approaches that adapt different mobile system scenarios. The research study presented in this thesis provides a novel interference mitigation scheme, based on power control and time-domain inter-cell interference coordination to improve cell and users’ throughputs. In addition, powerful scheduling algorithms have been developed and optimised to adapt the proposed scheme for both macro and small cells. It is responsible for the optimum resource allocation to minimise the inter-cell interference to the minimum ranges. The focus of this work is for downlink inter-cell interference in Long Term Evolution (LTE- Advanced) mobile networks, as an example of OFDMA (orthogonal frequency division multiple access)-based networks. More attention is paid to the Pico cell as an important cell type in heterogeneous deployment, due to the direct backhauling with the macro cell to coordinate the resource allocation among cells tightly and efficiently. The intensive simulations and results analyses show that the proposed scheme demonstrates better performance with less complexity in terms of user and cell throughputs, and spectral efficiency, as compared with the previously employed scheme.

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Pitakanda, Pitakandage Tinith Asanga. "Cooperative uplink Inter-Cell Interference (ICI) mitigation in 5G networks." Thesis, University of Hertfordshire, 2017. http://hdl.handle.net/2299/17958.

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In order to support the new paradigm shift in fifth generation (5G) mobile communication, radically different network architectures, associated technologies and network operation algorithms, need to be developed compared to existing fourth generation (4G) cellular solutions. The evolution toward 5G mobile networks will be characterized by an increasing number of wireless devices, increasing device and service complexity, and the requirement to access mobile services ubiquitously. To realise the dramatic increase in data rates in particular, research is focused on improving the capacity of current, Long Term Evolution (LTE)-based, 4G network standards, before radical changes are exploited which could include acquiring additional spectrum. The LTE network has a reuse factor of one; hence neighbouring cells/sectors use the same spectrum, therefore making the cell-edge users vulnerable to heavy inter cell interference in addition to the other factors such as fading and path-loss. In this direction, this thesis focuses on improving the performance of cell-edge users in LTE and LTE-Advanced networks by initially implementing a new Coordinated Multi-Point (CoMP) technique to support future 5G networks using smart antennas to mitigate cell-edge user interference in uplink. Successively a novel cooperative uplink inter-cell interference mitigation algorithm based on joint reception at the base station using receiver adaptive beamforming is investigated. Subsequently interference mitigation in a heterogeneous environment for inter Device-to-Device (D2D) communication underlaying cellular network is investigated as the enabling technology for maximising resource block (RB) utilisation in emerging 5G networks. The proximity of users in a network, achieving higher data rates with maximum RB utilisation (as the technology reuses the cellular RB simultaneously), while taking some load off the evolved Node B (eNodeB) i.e. by direct communication between User Equipment (UE), has been explored. Simulation results show that the proximity and transmission power of D2D transmission yields high performance gains for D2D receivers, which was demonstrated to be better than that of cellular UEs with better channel conditions or in close proximity to the eNodeB in the network. It is finally demonstrated that the application, as an extension to the above, of a novel receiver beamforming technique to reduce interference from D2D users, can further enhance network performance. To be able to develop the aforementioned technologies and evaluate the performance of new algorithms in emerging network scenarios, a beyond the-state-of-the-art LTE system-level-simulator (SLS) was implemented. The new simulator includes Multiple-Input Multiple-Output (MIMO) antenna functionalities, comprehensive channel models (such as Wireless World initiative New Radio II i.e. WINNER II) and adaptive modulation and coding schemes to accurately emulate the LTE and LTE-A network standards.

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Plass, Simon. "Cellular MC-CDMA downlink systems coordination, cancellation, and use of inter-cell interference." Düsseldorf VDI-Verl, 2008. http://d-nb.info/990760375/04.

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Shah, Bilal, and Suman Ghimire. "Understanding and Development of Inter-cell Interference Mitigation mechanism in LTE-A Heterogeneous Network." Thesis, Karlstads universitet, Avdelningen för fysik och elektroteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-29207.

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In long term evolution Advanced (LTE-A), concept of heterogeneous network (HetNet) has been introduced. Since, spectrum has become a rare resource these days; another mean is to be looked after to improve the existing wireless technology. One possible way is to improve the network topology so that frequency spectrum can be reused. In heterogeneous network, lower power nodes like Pico/Femto cell are deployed inside Macro cell to increase the system throughput and network coverage. Traditionally, cell selection for user equipment (UE) in LTE is based upon the received downlink power but these Pico/Femto cell have a low power than the Macro cell, meaning that few users can get access from Femto/Pico cells. UE should be close to the Pico/Femto cell to get connected with it. So its solution is; cell selection based upon the uplink path loss can be applied allowing more UE get connected to Pico/Femto cell. On doing that area of the Pico/Femto cell will increase which is called range extension region. Another problem arises when cell extension is applied, is that Macro cell imposes interference towards the Physical channel and signal of the Pico/Femto cell UE in range extension region as both Macro and Pico/Femto cell operate with same set of frequencies. 3rd Generation Partnership Project (3GPP) LTE-A Enhanced Inter-Cell Interference Coordination (eICIC) scheme has proposed Almost Blank Sub-frame (ABS) as a solution towards the above mentioned interference problem by reducing the activity or muting the Macro sub-frame. So that the corresponding Pico/Femto sub-frame can transmit the user information without interference from Macro cell ABS. For the reason of backward compatibility ABS still transmit certain physical channel and signals like CRSs, PCH, PBCH and PSS/SSS. So, interference still remains in these signals and channels. The main focus of thesis is reducing the impact of collision of cell-specific reference signal (CRS) from Macro and Femto cell as CRS is used for channel estimation. We have developed LTE link level system model for Macro and Femto cell in the Matlab simulator. Effect of difference in power of Macro and Femto CRS on UE under different noise power is investigated. It shows, higher the power of Macro, higher is the interference level. As a result Femto channel estimation quality degrades which in-turn degrades system performance. Combined receiver Interference cancelation (IC) methodology is implemented to reduce the impact of interference between macro and Femto CRS collision, which is based upon the reference signal received power (RSRP). System performance is evaluated with bit error rate (BER) and block error rate (BLER) versus Signal to Noise Ratio (SNR) and compared with the single cell system (without interference) and without IC system. Result confirms that IC method system performance is far better than system without IC and as close to system performance of single cell without interference. Furthermore, use of convolutional encoder, offer approximately 7dB coding gain in terms of SNR.

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Trabelsi, Nessrine. "A Game Theoretic Framework for User Association & Inter-cell Interference Management in LTE Cellular Networks." Thesis, Avignon, 2016. http://www.theses.fr/2016AVIG0215/document.

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Conduit par une croissance exponentielle dans les appareils mobiles et une augmentation continue de la consommation individuelle des données, le trafic de données mobiles a augmenté de 4000 fois au cours des 10 dernières années et près de 400millions fois au cours des 15 dernières années. Les réseaux cellulaires homogènes rencontrent de plus en plus de difficultés à gérer l’énorme trafic de données mobiles et à assurer un débit plus élevé et une meilleure qualité d’expérience pour les utilisateurs.Ces difficultés sont essentiellement liées au spectre disponible et à la capacité du réseau.L’industrie de télécommunication doit relever ces défis et en même temps doit garantir un modèle économique pour les opérateurs qui leur permettra de continuer à investir pour répondre à la demande croissante et réduire l’empreinte carbone due aux communications mobiles. Les réseaux cellulaires hétérogènes (HetNets), composés de stations de base macro et de différentes stations de base de faible puissance,sont considérés comme la solution clé pour améliorer l’efficacité spectrale par unité de surface et pour éliminer les trous de couverture. Dans de tels réseaux, il est primordial d’attacher intelligemment les utilisateurs aux stations de base et de bien gérer les interférences afin de gagner en performance. Comme la différence de puissance d’émission est importante entre les grandes et petites cellules, l’association habituelle des mobiles aux stations de bases en se basant sur le signal le plus fort, n’est plus adaptée dans les HetNets. Une technique basée sur des offsets individuelles par cellule Offset(CIO) est donc nécessaire afin d’équilibrer la charge entre les cellules et d’augmenter l’attraction des petites cellules (SC) par rapport aux cellules macro (MC). Cette offset est ajoutée à la valeur moyenne de la puissance reçue du signal de référence(RSRP) mesurée par le mobile et peut donc induire à un changement d’attachement vers différents eNodeB. Comme les stations de bases dans les réseaux cellulaires LTE utilisent les mêmes sous-bandes de fréquences, les mobiles peuvent connaître une forte interférence intercellulaire, en particulier en bordure de cellules. Par conséquent, il est primordial de coordonner l’allocation des ressources entre les cellules et de minimiser l’interférence entre les cellules. Pour atténuer la forte interférence intercellulaire, les ressources, en termes de temps, fréquence et puissance d’émission, devraient être alloués efficacement. Un modèle pour chaque dimension est calculé pour permettre en particulier aux utilisateurs en bordure de cellule de bénéficier d’un débit plus élevé et d’une meilleure qualité de l’expérience. L’optimisation de tous ces paramètres peut également offrir un gain en consommation d’énergie. Dans cette thèse, nous proposons une solution dynamique polyvalente effectuant une optimisation de l’attachement des mobiles aux stations de base et de l’allocation des ressources dans les réseaux cellulaires LTE maximisant une fonction d’utilité du réseau qui peut être choisie de manière adéquate.Notre solution, basée sur la théorie des jeux, permet de calculer les meilleures valeurs pour l’offset individuelle par cellule (CIO) et pour les niveaux de puissance à appliquer au niveau temporel et fréquentiel pour chaque cellule. Nous présentons des résultats des simulations effectuées pour illustrer le gain de performance important apporté par cette optimisation. Nous obtenons une significative hausse dans le débit moyen et le débit des utilisateurs en bordure de cellule avec 40 % et 55 % de gains respectivement. En outre, on obtient un gain important en énergie. Ce travail aborde des défis pour l’industrie des télécoms et en tant que tel, un prototype de l’optimiseur a été implémenté en se basant sur un trafic HetNets émulé
Driven by an exponential growth in mobile broadband-enabled devices and a continue dincrease in individual data consumption, mobile data traffic has grown 4000-fold over the past 10 years and almost 400-million-fold over the past 15 years. Homogeneouscellular networks have been facing limitations to handle soaring mobile data traffic and to meet the growing end-user demand for more bandwidth and betterquality of experience. These limitations are mainly related to the available spectrumand the capacity of the network. Telecommunication industry has to address these challenges and meet exploding demand. At the same time, it has to guarantee a healthy economic model to reduce the carbon footprint which is caused by mobile communications.Heterogeneous Networks (HetNets), composed of macro base stations and low powerbase stations of different types, are seen as the key solution to improve spectral efficiency per unit area and to eliminate coverage holes. In such networks, intelligent user association and interference management schemes are needed to achieve gains in performance. Due to the large imbalance in transmission power between macroand small cells, user association based on strongest signal received is not adapted inHetNets as only few users would attach to low power nodes. A technique based onCell Individual Offset (CIO) is therefore required to perform load balancing and to favor some Small Cell (SC) attraction against Macro Cell (MC). This offset is addedto users’ Reference Signal Received Power (RSRP) measurements and hence inducing handover towards different eNodeBs. As Long Term Evolution (LTE) cellular networks use the same frequency sub-bands, mobile users may experience strong inter-cellxv interference, especially at cell edge. Therefore, there is a need to coordinate resource allocation among the cells and minimize inter-cell interference. To mitigate stronginter-cell interference, the resource, in time, frequency and power domain, should be allocated efficiently. A pattern for each dimension is computed to permit especially for cell edge users to benefit of higher throughput and quality of experience. The optimization of all these parameters can also offer gain in energy use. In this thesis,we propose a concrete versatile dynamic solution performing an optimization of user association and resource allocation in LTE cellular networks maximizing a certainnet work utility function that can be adequately chosen. Our solution, based on gametheory, permits to compute Cell Individual Offset and a pattern of power transmission over frequency and time domain for each cell. We present numerical simulations toillustrate the important performance gain brought by this optimization. We obtain significant benefits in the average throughput and also cell edge user through put of40% and 55% gains respectively. Furthermore, we also obtain a meaningful improvement in energy efficiency. This work addresses industrial research challenges and assuch, a prototype acting on emulated HetNets traffic has been implemented

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14

Islam, MD Jhirul, and Mohammed Nazmul Haider Chowdhury. "Study of inter-cell interference and its impact on the quality of video conference traffic in LTE Network." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5070.

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While inter-cell interference coordination (ICIC) for the downlink and uplink of multi-cell systems (in general) and orthogonal frequency division multiple access (OFDMA) networks (in particular) have been extensively studied, the study of the impact caused by inter-cell interference with video conferencing traffic has received less attention. The consideration of video conferencing traffic is essential for analyzing the overall performance analysis of inter-cell interference in LTE networks, and in particular for the evaluation of the video conferencing traffic. In LTE networks, the same frequencies can be used in several adjacent cells. This means that in practice every cell may have other cell nearby whose radio transmissions may interfere with the own signal. In this paper, we report a comprehensive analysis on the performance of video traffic considering the inter-cell interference impact in LTE network. The interference patterns are configured by using the OPNET simulator for a given set of parameters, such as cell configuration, user configurations, and traffic models. The interference pattern is used to study the performance of video conferencing traffic in LTE network for realistic deployments. We, present a detailed description of the way to model the network in OPNET platform considering the inter-cell interference. In order to use the suggested network model in OPNET platform three network scenarios are configured. They are fully overlapped, half overlapped and no frequency overlapping. These scenarios are configured in such a way to show how the video traffic is impacted when the network load increases. The thesis shows that the video conferencing traffic experiences more delay and loss when fully overlapped frequency is used in the adjacent cell on LTE network.
Moammed Nazmul Haider Chowdhury C/o,Huq M A Visattravagen 30 LGH 1010 Huddinge 14150 Mobile:+46760996255 Mob:

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15

Aziz, Danish [Verfasser], and Joachim [Akademischer Betreuer] Speidel. "Un-coordinated multi-user and inter-cell interference alignment based on partial and outdated information for large cellular networks / Danish Aziz ; Betreuer: Joachim Speidel." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118369572/34.

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Ahmed, Rana R. "Performance Modelling and Analysis of a New CoMP-based Handover Scheme for Next Generation Wireless Networks. Performance Modelling and Analysis for the Design and Development of a New Handover Scheme for Cell Edge Users in Next Generation Wireless Networks (NGWNs) Based on the Coordinated Multi-Point (CoMP) Joint Transmission (JT) Technique." Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/16785.

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Inter-Cell Interference (ICI) will be one of main problems for degrading the performance of future wireless networks at cell edge. This adverse situation will become worst in the presence of dense deployment of micro and macro cells. In this context, the Coordinated Multi-Point (CoMP) technique was introduced to mitigate ICI in Next Generation Wireless Networks (NGWN) and increase their network performance at cell edge. Even though the CoMP technique provides satisfactory solutions of various problems at cell edge, nevertheless existing CoMP handover schemes do not prevent unnecessary handover initialisation decisions and never discuss the drawbacks of CoMP handover technique such as excessive feedback and resource sharing among UEs. In this research, new CoMP-based handover schemes are proposed in order to minimise unnecessary handover decisions at cell edge and determine solution of drawbacks of CoMP technique in conjunction with signal measurements such as Reference Signal Received Power (RSRP) and Received Signal Received Quality (RSRQ). A combination of calculations of RSRP and RSRQ facilitate a credible decision making process of CoMP mode and handover mode at cell edge. Typical numerical experiments indicate that by triggering the CoMP mode along with solutions of drawbacks, the overall network performance is constantly increase as the number of unnecessary handovers is progressively reduced.

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17

Hsu, Chia-Shiu, and 許嘉修. "Inter Cell Interference Reduction of LMDS Systems by Cell Planning." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/8g6k5c.

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碩士
國立中央大學
通訊工程研究所碩士在職專班
94
In wireless cellular systems, co-channel interference is the limiting factor to system performance. Fix wireless systems such as Local Multipoint Distribution Systems (LMDS) is no exception to this rule. Because the LMDS transmission is usually higher-capacity, and the beam-width of subscribers’ antenna is narrow beam width, therefore co-channel interference in LDMS systems is more important. This thesis proposes a concept of subscribers’ antenna reorientation along with variable threshold dynamic modulation (VTDM) to reduce this interference. Using this scheme, we can get the better spectrum efficiency and reduce the interfering regions so that improve the system performance.

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18

Hu, Chih-Ming, and 胡智明. "Inter Cell Interference mitigation in OFDMA cellular system." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/57615618868533478076.

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碩士
國立中央大學
通訊工程研究所碩士在職專班
98
With the fast development of the wireless communications, the requirement of faster transmission rate has also increased rapidly. The OFDMA technology is considered as a promising candidate for the downlink interface of the next generation wireless systems. However, inter cell interference is an impediment of the throughput performance in the system, especially for Cell Edge Users(CEUs).The main goal is to improve the CEU throughput as well as overall cell throughput. In this thesis, we propose a flexible softer frequency reuse scheme. Several schemes on inter cell interference coordination have been suggested for OFDMA systems. Our algorithm is designed to improve the CEU throughput by optimizing the reuse factor、power factor and packet scheduler priority. From the simulation result, the proposed algorithm can increase the CEU throughput effectively.

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Kao, Yi-Hung, and 高一弘. "Methods for Inter-Cell Interference Mitigation in Dense Small Cell Networks." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9d333g.

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碩士
國立交通大學
電信工程研究所
107
In 5G communication systems, ultra dense small network (UDN) is one of the important topics for satisfying the proliferation of users' demanded data rate in recent years. Although UDN have been proved effective to improve the performance of users by reducing loading of each cell and improving the spatial efficiency of wireless transmissions, the co-channel interference between small cells may become the bottleneck that restricts the improvement of users' performance. In literature, enhanced inter-cell interference coordination (eICIC) and futher enhanced inter-cell interference coordination (feICIC) techniques are proposed to mitigate interference between macro cells and pico cells in a heterogeneous network (HetNet). The discussion of how eICIC and feICIC work in UDN is still lacking. This motivate us to extend eICIC and feICIC to mitigate the inter-cell interference between cells in UDN. In our work, we extend eICIC and feICIC to UDN and provide the analysis of user's average data rate. After deriving the average throughput of users, we find the best ABS/LPSF ratio and power reduction ratio by maximize the system utility. Additionally, we notice the importance of choosing suitable ABS/LPSF provider in UDN. Different from HetNet, there is no distinction in BSs like macro BSs and pico BSs in UDN. Hence, any BS in UDN could be an ABS /LSPF provider on condition that it has spare resource to support other BSs' users. Motivated by this, we propose a provider choosing algorithm, which take BSs' loading and users's average throuhgput into consideration, to find a set of providers that improve the performance of low throughput users. In the final part, we propose a subframe by subframe power control algorithm, which is extended from the concept of feICIC, that increases the fairness of network system and saves about 20\% BS transmission power in the same time.

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Wu, Yu-Sheng, and 吳昱陞. "Performance Improvement of OFDMA Systems under Inter Cell Interference." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/3ymbg4.

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碩士
國立臺北科技大學
電機工程系研究所
101
The wireless communications is fasted development, the requirement of transmission bandwidth and capacity have increased for users. The OFDMA technology is considered next generation wireless system. In OFDMA system, inter cell interference is a serious problem for cell edge users, it effect performance and total capacity of cell. This thesis mainly researches into the performance improvement of OFDMA system under inter cell interference, we proposed cell region、users distance and minimum power to schedule priority to improve system performance.

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21

Xia, Ping. "Interference management in heterogeneous cellular networks." 2012. http://hdl.handle.net/2152/19584.

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Heterogeneous cellular networks (HCNs) – comprising traditional macro base stations (BSs) and heterogeneous infrastructure such as microcells, picocells, femtocells and distributed antennas – are fast becoming a cost-effective and essential way of handling explosive wireless data traffic demands. Up until now, little basic research has been done on the fundamentals of managing so much infrastructure – much of it unplanned – together with the carefully planned macro-cellular network. This dissertation addresses the key technical challenges of inter-cell interference management in this new network paradigm. This dissertation first studies uplink femtocell access control in uncoordinated two-tier networks, i.e. where the femtocells cannot coordinate with macrocells. Closed access allows registered home users to monopolize their own femtocell and its backhaul connection, but also results in severe interference between femtocells and nearby unregistered macro users. Open access reduces such interference by handing over such users, at the expense of femtocell resource sharing. In the first analytical work on this topic, we studied the best femtocell access technique from the perspectives of both network operators and femtocell owners, and show that it is strongly contingent on parameters such as multiple access schemes (i.e. orthogonal vs. non- orthogonal) and cellular user density (in TDMA/OFDMA). To study coordinated algorithms whose success depends heavily on the rate and delay (vs. user mobility) of inter-cell overhead sharing, this dissertation develops various models of overhead signaling in general HCNs and derives the overhead quality contour – the achievable set of overhead packet rate and delay – under general assumptions on overhead arrivals and different overhead signaling methods (backhaul and/or wireless). The overhead quality contour is further simplified for two widely used models of overhead arrivals: Poisson and deterministic. Based on the overhead quality contour that is applicable to generic coordinated techniques, this dissertation develops a novel analytical framework to evaluate downlink coordinated multi-point (CoMP) schemes in HCNs. Combined with the signal-to-interference-plus-noise-ratio (SINR) characterization, this framework can be used for a class of CoMP schemes without user data sharing. As an example, we apply it to downlink CoMP inter-cell interference cancellation (ICIC), after deriving SINR results for it using the spatial Poisson Point Process (PPP) to capture the uncertainty in base station locations.
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22

Chiou, Ching-Jiun, and 邱慶俊. "Inter Cell Interference Reduction of LMDS for the downlink direction." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/45323254909652595441.

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碩士
國立中央大學
通訊工程研究所
93
In wireless cellular systems, co-channel interference is the limiting factor to system performance. Fix wireless systems such as Local Multipoint Distribution Systems (LMDS) are no exception to this rule. Because the LMDS downlink is usually higher-capacity and beam-width of subscribers’ antenna is narrow beam width, therefore co-channel interference in downlink is more serious. This thesis proposes a concept of subscribers’ antenna reorientation to reduce this interference. Using this scheme, we can reduce the interfering regions and improve the system performance.

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Cheng, Nan-hung, and 鄭南宏. "UE assisted inter-cell interference cancellation in femtocell network system." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/24772471590667297724.

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碩士
國立中央大學
通訊工程學系
103
In recent years, demand for high-quality mobile communications is significant increasing. In the future, in order to meet the large and wide variety of needs, there will be many different back-end network and different power of base stations coexist. Therefore, heterogeneous network has been widely discussed in recent years. Femtocell network are considered suitable for next-generation mobile communication because it is small size that can place in the office and house and it can solve inadequate coverage of mobile communication problem. Femtocell network has been discussed at the end of 3G, but the reason that it could not have been developed is the problem of interference coordination. Interference is divided into two categories. The first interference is from large base stations and the second interference is femtocell base stations with each other. These interference will affect network quality of users, network delays, disconnection and signal problems, so we must discuss interference coordination (inter-cell interference coordination, ICIC) first.

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Chen, Yu-Chieh, and 陳鈺杰. "QoE-Aware Inter-Cell Interference Mitigation for Dynamic TDD Networks." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/74963534669852832455.

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碩士
國立臺灣大學
電機工程學研究所
104
In LTE dynamic time division duplexing (dynamic TDD), seven uplink-downlink configurations (UL-DL configurations) are supported to accommodate downlink/uplink traffic asymmetry for traffic adaptation. The Third Generation Partnership Project (3GPP) has considered the opportunity of adopting such dynamic adaptation of UL-DL configurations in small cell networks to enlarge the network capacity. However, dynamic TDD inducing opposite transmission directions in different cells results in new destructive interference components, i.e., BS-to-BS and UE-to-UE interference, which makes the inter-cell interference in small cell networks even worse. In this paper, a QoE-aware interference mitigation scheme is proposed to mitigate interference and to manage QoE as well in small cell deployment networks. The scheme explicitly uses the received signal strength and QoE state of users to generate a QoE-aware interference graph, where vertices represent cells, edges represent intolerant inter-cell interference among the incident cells and weights represent the utility increment of QoE. Then, a graph-based optimisation problem is formulated to determine which cells are allowed to transmit to maximize the system utility of QoE. Further, a linear-time approximation algorithm is proposed for large-scale deployment environments. The LTE-based simulation results show that the proposed QoE-aware interference mitigation scheme significantly improves overall QoE and also alleviate inter-cell interference. Finally, based on the simulation, we provide some insight into QoE management and interference mitigation in both homogeneous and heterogeneous networks operating dynamic TDD.

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Jiang, Li-An, and 江禮安. "Inter-cell Interference Management under Imperfect Channel State Information at Transmitter." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/54148068327155854134.

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碩士
國立臺灣大學
電信工程學研究所
103
For future wireless communication, more and more small cells will be established, there are more likely to interfere each other. Thus inter-cell interference management will be an important issue. From the point of view of information theory, the simplest interfering links can be modeled as a two-user interference channel (IC). For this IC model, a partial interference cancellation (PIC) method called Han-Kobayashi scheme can achieve the best-known achievable rate region. However, it needs perfect (precise and global) channel state information (CSI). For practical communication, CSI is usually imperfect (imprecise and local) due to channel estimation error and locality respectively. Hence the performance of the PIC scheme will be reduced inevitably. For this thesis, we analyze the performance of two-user IC with the PIC scheme and imprecise CSI. In addition, we utilize the local CSI to propose a dynamic power allocation algorithm combined the PIC scheme for fading IC. It''s shown that the performance is obviously enhanced compared with some traditional schemes. We further extend above result to uplink cellular with inter-cell interference, and combine the successive interference cancellation (SIC) and user-scheduling to analyze its performance.

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Kuo, Yen-Wei, and 郭彥蔚. "Fuzzy-Based Inter-Cell Interference Coordination in LTE/LTE-A Heterogeneous Networks." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/wvy35f.

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博士
國立中央大學
資訊工程學系
104
The Long Term Evolution (LTE) Heterogeneous Networks (HetNet) consists of several different type of base station for providing different coverage and capacity and increasing network capacity continuously. In LTE HetNet, the mass deployment and frequently on/off of small cells, such as femtocells, causes severe inter-cell interference problem due to the nature of user deployment without X2 interface, especially in Closed Subscriber Group (CSG) mode. The concept of Inter-Cell Interference Coordination proposed by The 3rd Generation Partnership Project (3GPP) can be achieved by using power restriction or resource restriction methods. In this article, we proposed two distributed fuzzy-based Inter-Cell Interference Coordination (ICIC) algorithms based on the concept of the power restriction and resource restriction. The low complexity and high flexibility of the proposed algorithms is benefited from the fuzzy Multi-Attributes Decision Making (MADM). Fuzzy theory can provide means to make approximate decisions with low complexity and high flexibility, especially in current multi-parameters communication systems, such as LTE system, in which the diversity of network metrics can help fuzzy system to make better decision. The proposed adaptive power restriction algorithm provides an appropriate serving range for femtocells, determining center zone and separating UEs into cell center and cell edge for frequency-reused algorithms, such as Soft Frequency Reuse (SFR) and Fractional Frequency Reuse (FFR), without complicated negotiation among cells. The proposed adaptive radio restriction algorithm weighs the trade-off between coverage and capacity by leveraging three system metrics to make an appropriate scheduling decision to avoid the conflict in radio resource used among cells. In particular, there are no fixed fuzzy logic rules and shaped fuzzy membership model compared to conventional fuzzy-based algorithms. The simulation results show that proposed algorithms provide about 49 % data rate improvement for femtocell and about 18 % data rate improvement for macrocell compared to current link adaptation algorithm. In addition, it can achieve up to 56 % data rate and 89 % radio resource efficiency of the up bound case.

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Chiu, Che-Sheng, and 邱哲盛. "A Study on Inter-Cell Interference Mitigation Schemes for OFDMA Downlink Systems." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/81919402686715467175.

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博士
國立交通大學
電信工程研究所
100
Thanks to its effectiveness of improving spectral efficiency and its capability of combating frequency selective fading, orthogonal frequency division multiple access (OFDMA) has been widely adopted in the next generation (i.e. 4th generation (4G)) mobile communication systems as downlink transmission scheme. Considering an OFDMA downlink system, signals originating from the same cell are orthogonal, while those from different cells interfere with each other. As a consequence, inter-cell interference (ICI) becomes a major performance degradation factor, especially on cell borders. Nevertheless, for developing next generation mobile communication systems, a more homogeneous distribution of user data rate over the coverage area is highly desirable. To meet this end, ICI must be effectively managed. In this dissertation, we have studied ICI mitigation schemes in OFDMA systems and especially, we focus on the downlink side. The objective of ICI mitigation is to provide better service to cell edge users without sacrificing cell throughput. In emerging 4G cellular systems, inter-cell interference coordination (ICIC) is considered as a promising technique to deal with the ICI. Among the variety of ICIC strategies, the soft frequency reuse (SFR) scheme and the parital frequency reuse (PFR) scheme are widely accepted. In the first part of this research, we review and compare the throughput performance of PFR and SFR in a multi-cell OFDMA downlink system and especially, this work is done by using the signal strength difference based (SSD-based) user grouping method, which is recommended by Long Term Evolution (LTE) standard. We show that both PFR and SFR are very effective ways to cope with ICI in an OFDMA downlink system, but PFR is a more appropriate one to achieve data-rate fairness among users with having an acceptable system capacity. It is well-known that soft handover is a key technique to extend the cell coverage and to increase the cell edge user data rate in 3G cellular communication systems. In the second part of this research, we deliver a hybrid ICI mitigation scheme which combines PFR and soft handover. Its basic principle is to dynamically choose between a partial frequency reuse scheme (with a reuse factor of 3) and a soft handover scheme to provide better signal quality for cell edge users. Simulation results show that this hybrid scheme yields a significant cell edge throughput gain over the standard PFR scheme. Furthermore, considering data rate fairness among users, the proposed hybrid method also outperforms the standard PFR scheme in total cell throughput. Traditionally, mobile cellular networks are typically deployed as homogeneous networks in which only high-power macro base stations are contained. Recently, heterogeneous networks (HetNets) or multi-layered network, in which low-power nodes (LPNs) are deployed within macrocell layout, has attracted a lot of interest as a way to maximize system capacity per unit area. Moreover, in order to extent the coverage region of open access LPNs and hence offload more traffics from macrocells, cell range expansion (CRE) strategy is suggested to apply in HetNets. However, assuming a co-channel macro-pico HetNet, the total network throughput could actually decrease due to CRE if the inter-layer interference couldn’t be effectively managed. The third part of this research presents an inter-layer interference coordination (ILIC) scheme for an OFDMA co-channel macro-pico HetNet that carries out CRE technique. Our simulation results confirm that the proposed ILIC scheme can lead to a significant improvement in link quality for those users in the extended region and thus reduce user outage rate in the system; and further, it can provide a substantial total area throughput gain over the conventional reuse-1 scheme.

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Yu, Chih-Ming, and 尤志明. "Improve the Inter-cell Interference in Multi-user OFDM Based on LMDS." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/51656498674021107073.

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碩士
國立中央大學
電機工程研究所
91
In wireless cellular systems, co-channel interference is the limiting factor to system performance. Fixed wireless systems such as Local Multipoint Distribution Service (LMDS) is no exception to this rule. In LMDS, because the downlink is usually higher capacity and the narrow beam of subscriber’s antenna is an interference-limiting factor, the downlink interference is more serious. Consequently, improve of co-channel interference on the downlink direction of LMDS is the subject of this thesis. In OFDM systems, data is transmitted simultaneously on parallel sub-carriers, each occupying a small fraction of the available bandwidth. The basic principle of OFDM is to split a high-rate data into a number of lower rate system. Multi-user OFDM is a promising new modulation technique for wireless communications. It includes many of the advantages of broadcast OFDM that is used for Digital Audio Broadcasting (DAB) and for Digital Video Broadcasting (DVB) in Europe and Australia. OFDM was selected for these systems primarily because of its high spectral efficiency and multi-path tolerance. OFDM/FDMA is one of the multi-user OFDM multiple access. In OFDM/FDMA, the number of sub-carriers for a specific user can be varied, according to the required data rate. In the simplest OFDM/FDMA system, each user occupy fixed group of sub-carriers. We consider parts of the sub-carrier be used. Then we can improve system by using sub-carriers allocation. In this thesis, we proposed a simple sub-carriers allocation method compared to the convention and random OFDM/FDMA.

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29

Chung-HauYu and 俞中豪. "Coordinating Inter-cell Interference through Positive Feedback for LTE-Advanced Uplink Transmission." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/57237308898072889578.

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碩士
國立成功大學
資訊工程學系碩博士班
101
In Orthogonal Frequency Division Multiplex based system, inter-cell interference is an important issue, which impacts signal quality between evolved NodeBs and user equipments (UEs), especially for UEs at cell edge. In order to relieve this issue for uplink in Long Term Evolution-Advanced system, Third Generation Partnership Project defines high interference indicator (HII) and overload indicator (OI) to coordinate interference. HII provides negative feedback to prevent inappropriate resource allocation. OI is used to notify neighboring cells of an interference overload event. In this thesis, we investigate the performance of existing schemes based on HII and OI. Then we propose a scheme with positive feedback by introducing a new indicator to work with HII and OI to ensure improvement of system performance. Simulation results show that our scheme can effectively enhance average uplink throughput of cell edge UEs as well as the total uplink throughput.

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30

Wang, Chih-Yao, and 王致堯. "Performance Analysis of Resource Allocation Algorithms in OFDMA Systems with Inter-Cell Interference." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/48e7zw.

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碩士
國立臺北科技大學
電機工程系研究所
101
This thesis mainly researches into the performance improvement of adaptive resource allocation algorithms in OFDMA systems with inter-cell interference. The traditional resource allocation algorithm uses the given user’s channel responses to do resource allocation and it doesn’t consider the inter-cell interference caused by the neighbor base stations. But the inter-cell interference does affect the optimal resource allocation of systems especially for large interference. The quantity of inter-cell interference is usually computed by transmission powers of neighbor base stations and path losses due to distances between the user and neighbor base stations. In this thesis, we first build the relation between the user’s channel response and the distance between the user to the base station. And then we propose a proportional rate constraint adaptive resource allocation algorithm which considers the factor of inter-cell interference. From computer simulation, it shows that our method is better than all other algorithms for both Shannon capacity and adaptive modulation.

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31

Lo, Kang-Hao, and 羅康豪. "Study of De-centralized Inter-Cell Interference Coordination Method in LTE Downlink System." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/9gge5z.

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碩士
國立中央大學
通訊工程學系
103
Inter-cell Interference coordination (ICIC) has been more and more important in the 3rd Generation Partnership Project’s (3GPP’s) Long Term Evolution –Advanced (LTE-A) standardization since the Frequency Reuse Factor (FRF) has already been 1 which means we utilized whole frequency without partition into several segmentations. Meanwhile, with radio access networks in LTE/LTE-A are flatter, decentralized ICIC algorithm has become more suitable than the centralized algorithm. Because of the import of the Load Information (LI) through X2 interface, ICIC could be effectively used to reduce the interference of edge users in LTE/LTE-A system. In the multi-cell radio resource management of LTE/LTE-A system, ICIC plays a significant role in enhancing cell edge spectrum efficiency. In this thesis, we propose a decentralized ICIC method, named relative throughput based resource block coordination (RTRBC), to coordinate the interference between eNBs. By comparing the relative gain and loss in heuristic manner, the proposed scheme negotiates the RB usage between adjacent eNBs to achieve higher throughput. The simulation results also demonstrate the effectiveness of the proposed scheme.

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32

Chou, Chen-Hsiao, and 周振孝. "Inter-Cell Interference Control for Heterogeneous Wireless Networks in 3GPP LTE-Advanced Systems." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/31228323861154670280.

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碩士
國立交通大學
電信工程研究所
100
Since there are more demands for high data rates, the 3rd Generation Partnership Project (3GPP) has already published many researches and contributions about increasing the spectral efficiency. We have seen a lot of studies on coordinated multipoint transmission and reception techniques for the LTE-A systems. The main perspectives of these approaches aim at mitigating the inter-cell interference and also increasing the system performance. Recently, several coordinated multipoint (CoMP) transmission techniques have already been investigated. This thesis presents a joint cooperation design based on CoMP operations. Our design will combine cooperation between intra-site with remote radio head and inter-site with available backhaul. The gaol of this thesis is to evaluate the improvement by a joint design method and provide a better strategy when combining the cooperation of both sites. Since we try to extend CoMP region from intra-site to inter-site, we have to exchange more channel state information and data between devices. This will increase the feedback time to complete reception. We consider that the delay effect should be included and evaluated. In addition, we will discuss the effects upon the system performance which are caused by different cell architectures. Several CoMP transmission techniques are operated in heterogeneous network. We use different ones in inter-site cooperation to compare the system performance of spectrum efficiency. Compared with other transmission schemes, the proposed scheme is a feasible method to enhance spectral efficiency.

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33

Liao, Zheng-Bo, and 廖政博. "Fraction Frequency Reuse-Based Inter-cell Interference Coordination Mechanism for LTE Downlink Transmission." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/78914276134469990786.

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碩士
國立交通大學
網路工程研究所
99
In recent year, people who need radio network are increasing, especially for the multimedia communication. To reach such demand, 4G cellular wireless network is working on. Long Term Evolution (LTE) is one of the 4G standards proposed by 3GPP. LTE is a cellular network system; this kind of system suffers from interference problem between cells. If we do not handle interference well, we cannot reach the goal of high transmission rate and high cell coverage. In traditional static interference avoidance scheme, different user distribution will cause wasting of resource. In this thesis we propose a fractional frequency based dynamic interference coordination scheme. By the scheme we can dynamic adjust the high power frequency band and normal power frequency band according to user distribution. Adjusting frequency band through this scheme can efficiently eliminate the resource wasting problem.

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34

林家鴻. "Downlink Synchronization and Inter-cell Interference Coordination of a 3GPP LTE-A System." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/09812624308760316125.

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碩士
國立臺灣海洋大學
通訊與導航工程學系
101
Because of the increasing demand of the transmission data rate for a wireless access service, the development of the fourth generation (4G) wireless communication system becomes more and more urgent and important. The Long Term Evolution Advanced (LTE-A) is the most popular candidate for the future 4G system, and it has some issues need to be investigated, such as Synchronization, Inter-cell interference, Channel Estimation (CE), etc. In this thesis, the synchronization and inter-cell interference problems are discussed. LTE-A adopts the PSSs and SSSs that transmit every 5ms for the synchronization. Several low-complexity schemes are provided to conduct the Timing Offset (TO) estimation via the time-domain symmetric property of PSS and conjugated symmetric property of SSS in this thesis. Computer simulations show that the proposed synchronization methods have not only the good Mean Square Error (MSE) performance but also the low computation complexity advantage. Besides, a sectorized Coordinated Multi-Point (CoMP) resource planning method is provided to avoid the macro cell to macro cell inter-cell interference. The proposed sectorized CoMP is compared with the traditional Inter-Cell Interference Coordination (ICIC) methods and results shows that the proposed method has better performance of system frequency efficiency and user capacity. Finally, a modified greedy method is also provided to achieve the fair resource allocation purpose for the UEs in this thesis.

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35

Lin, Cheng-Hsun, and 林承勳. "Assessment of the Downlink Capacity for WCDMA Networks through Intra- and Inter-Cell Interference." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/02268679127805901129.

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碩士
國立雲林科技大學
電機工程系碩士班
93
The third generation (3G) mobile communication systems provide a variety of service classes and have higher system capacity than previous mobile communication systems. WCDMA (Wideband Code Division Multiple Access) is one of major radio transmission technologies of 3G systems. Since service classes are so diverse, how to provide quality of services for varying classes is the issue that 3G systems must be tackled. This paper will focus on the assessment of the downlink channel capacity for WCDMA networks. First, we describe the characteristics and the important system parameters (e.g., intra-cell interference, inter-cell interference, and pathloss, etc.) of WCDMA systems. Then, we define the maximum available radio resource of the WCDMA downlink. With the results of simulation, we observe the characteristics of the intra-cell interference, inter-cell interference, and pathloss under various urban marco cell environments, and investigate their influences to the capacity of WCDMA downlink. Finally, we compare the simulation results to the defined downlink maximum available radio resource, and prove the accuracy of the derived formula as the assessment of the downlink capacity of WCDMA networks.

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36

Chen, Chien-Shiuan, and 陳建瑄. "Reducing inter-cell interference base on Dynamic Fractional Frequency Reuse (FFR) Mechanism in LTE." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/46058093939273235301.

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碩士
國立臺灣科技大學
電機工程系
101
In the LTE system, the bandwidth will be divided by the time and frequency into many resource blocks, then user can use these different resource blocks to transmit data. Thus LTE can avoid most intra cell interference. However, due to the cell doesn’t know what the situation of resource allocation by other neighboring cell, they will make interference to each other easily, called inter cell interference. In this situation, the user who is on the cell edge will suffer more interference. Thus, there are many papers proposed to solve the inter cell interference (ICI) problem, such as: FFR (Fractional Frequency Reuse) and SFR (Soft Frequency Reuse). Although these methods can avoid interference to nearby cell through restricting the available frequency resources in their own cell’s sectors, the available resources will be reduced. In addition, when network topology have changed, these methods doesn’t adjust their frequency resources of each sector, as a result, the overall throughput will be reduced. There are some researches proposed dynamic FFR and dynamic SFR to solve aforementioned problems. Although the dynamic adjustment method can enhance the overall throughput, avoiding ICI must be considered. That is, we have to adjust neighbor cell’s frequency at the same time, this will need much of the time to exchange data or massive calculation. So we propose a simple and fast algorithm to dynamically adjust frequency resources which don’t need to adjust neighbor cell’s frequency at the same time but still can avoid ICI.

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37

Liang-YouWang and 王良祐. "Fuzzy Q-Learning Process for Enhanced Inter-cell Interference Coordination in LTE Heterogeneous Networks." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/g49dxg.

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38

Lai, Wei-Po, and 賴韋博. "An Enhanced Inter-Cell Interference Coordination (eICIC) Configuration Algorithm In 5G mmWave Heterogeneous Network." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/bth26e.

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碩士
國立中央大學
資訊工程學系
106
In order to satisfy increasing traffic demands in 5G network. 5G provides mmWave technology. Beamforming is considered to be a promising technique to reduce the pathloss of mmWave. Beamforming is a signal processing by antenna arrays for directional signal transmission or reception. The directional signal can reduce the pathloss of mmWave very well. Besides, increasing traffic demands. 5G will also support Heterogeneous Network (HetNet). One of the key challenges is reducing the interference and maximizing the throughput. In LTE, it provides enhanced Inter-Cell Interference Coordination (eICIC) to reduce the interference of the cells. Clearly, an uniform eICIC in mmWave scenario can't fully utilize the beams capability. In this paper, we propose an non-uniform eICIC configuration algorithm to improve the throughput of the cells. Final, we use Gurobi to evaluate our performance

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39

吳志聰. "Using Multi-mode CDMA Scheme to Reduce Inter-cell Interference in Local Multipoint Distribution Service." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/08952619929309347196.

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碩士
國立中央大學
電機工程研究所
89
LMDS is the most obtrusive among mini-meter wave propagation techniques. Because it can provide wideband integrated services including two-way voice, video, and data transmission. The asymmetry between downstream and upstream is quite consistent with the normal data flow, particularly for residential applications. Of course the spectrum can also be used to provide symmetric traffic that would typically be required for business applications. In chapter 2, we propose a new cell planning, which suffers less inter-cell interference in comparison with the typical cell planning. Chapter 3 analyzes the technique of multi-mode CDMA scheme can reduce inter-cell interference effectively in clear air. Besides, high rainfall attenuation is a significant challenges associated with deploying systems at Ka band. Chapter 4 studies the multi-mode CDMA scheme is adequate in small rain rate condition. In large rain rate situation, we can maintain system performance by reducing cell size or by the process of power control. Finally, chapter 5 gives the conclusions.

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40

Guan-HongChen and 陳冠宏. "Coordinating Inter-cell Interference through Cognitive Radio for LTE-Advanced Downlink Transmission in Hierarchical Network." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/90639190253562039882.

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碩士
國立成功大學
資訊工程學系
103
In a hierarchical network, femtocells are deployed within a macroecell for improving throughput of indoor user equipments (UEs), which are referred to as femtocell UEs (FUEs). In such deployment, cross-tier interference is an important issue, which may significantly impact signal quality between macrocell base stations (MBSs) and macrocell user equipments (MUEs), especially for MUEs near the femtocell [12]. In order to relieve this problem, Third Generation Partnership Project Long Term Evolution-Advanced (3GPP LTE-A) defines the cognitive radio (CR)-enhanced femtocell to coordinate interference for downlink. CR-enhanced femtocells have the ability to sense radio environment to obtain radio parameters. In this paper, we investigate the performance of existing schemes based on fractional frequency reuse. Then we propose a scheme with cognitive radio technology to improve the performance of fractional frequency reuse scheme. Simulation results show that our scheme can effectively enhance average downlink throughput of FUEs as well as the total downlink throughput in hierarchical networks.

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41

Bai, Chen-Xuan, and 白承玄. "Implementation and Analysis of Time Synchronization for Inter-Cell Interference Coordination in Small Cells using OAI." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/2gdrxu.

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碩士
國立臺北科技大學
電子工程系
106
With the evolution of 5G communication, to enable users to achieve better communication quality and signal coverage, telecom operators and users may install more small cells in the indoor region. However, the small cells would suffer severe inter-cell interference due to denser deployment. The thesis explores the implementation issues of enhanced inter-cell interference (eICIC) coordination among small cells. The time-domain based eICIC, namely almost blank subframe (ABS), is utilized to avoid the concurrent transmission among the neighbor cells. According to the literature, the time synchronization requirement should be within 1$mu$s. Moreover, although the major part of each subframe, i.e., the data transmission interference through the physical downlink shared channel (PDSCH), is coordinated, the other portion of the subframe such as the synchronization signals and the physical broadcast channel (PBCH) would still interfere others. The subframe shifting among neighbor cells is further considered to improve the performance. We implement using OpenAirInterface (OAI) with universal software radio peripherals (USRP). To study the impact of time synchronization on the performance of eICIC, we utilize a packet-based protocol IEEE 1588 and compare with the clock source device OctoClock-G. In the experiments, three USRPs are installed to serve as two small cells and one user. One small cell transmits data to the user, and the other transmits as the interference source. We verified that the throughput of the time synchronization case could increase up to 28% compared to the asynchronous case, and the further consideration of subframe offset scheme will increase by 40% in total, which shows that user can get guarantee data transmission in the dense small cell.

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42

Hsu, Yi-Huai, and 徐逸懷. "Efficient Access Control for M2M Communications and Traffic Adaptive Inter-Cell Interference Coordination over LTE-A HetNets." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/97920992761338087289.

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博士
國立交通大學
資訊科學與工程研究所
104
Wireless data traffic has seen prolific growth in recent years because the use of smart handheld devices and new emerging services are widespread, such as real-time video streaming and multimedia file sharing. To handle huge wireless data traffic, LTE-A (Long Term Evolution-Advanced) has adopted heterogeneous networks (HetNets) architecture, which consists of macro eNB and pico eNB/relay node (RN), to increase the capacity of LTE-A. In LTE-A HetNets, access control for Machine-to-Machine (M2M) communications, energy saving, and inter-cell interference coordination are three important issues, which are to be resolved in this thesis. For the access control for M2M communications issue, we propose two efficient cooperative access class barring with load balancing (CACB-LB) and traffic adaptive radio resource management (TARRM) schemes for M2M communications. The proposed CACB-LB uses the percentage of the number of MTC devices that can only access one enhanced Node B (eNB) between two adjacent eNBs as a criterion to allocate those MTC devices that are located in the overlapped coverage area to each eNB. Note that an eNB is a base station of LTE-A. In this way, the proposed CACB-LB can achieve better load balancing among eNBs than CACB, which is the best available related work. The proposed CACB-LB also uses the ratio of the channel quality indication (CQI) that an MTC device received from an eNB over the number of MTC devices that attach to the eNB as a criterion to adjust the estimated number of MTC devices that may access the eNB. As a result, the proposed CACB-LB can have a better set of barring rates of access class barring than CACB and can reduce random access delay experienced by an MTC device, which is also applicable to user equipment (UE). In addition, the proposed TARRM allocates radio resources for an MTC device based on the random access rate of the MTC device and the amount of data uploaded and downloaded by the MTC device in a homogeneous MTC device network, and the priority of an MTC device in a heterogeneous MTC device network so as to effectively utilize the radio resources. For the energy saving issue, we propose a self-organizing network (SON)-based adaptive energy saving (AES) mechanism for LTE-A self-organizing HetNets. The proposed AES uses two-level multi-threshold load management for each RN under different eNBs (inter-cell level) and for each RN within the same eNB (intra-cell level) so as to reduce the congestion in hot spot eNBs and RNs. In addition, the proposed AES can dynamically switch an RN between active and sleep modes to maximize the number of sleep RNs for adaptive energy saving. It can also dynamically change an RN’s coverage area to reduce energy consumption and to increase radio resource utilization. Besides, the proposed AES adopts a neural network predictor to forecast the loading of each RN to determine whether it is appropriate to switch an RN to sleep mode. For the inter-cell interference coordination issue, we propose SON-based cell size adaption (SCSA) and traffic adaptive enhanced inter-cell interference coordination (TAeICIC) to resolve the interference problem. The proposed SCSA uses dynamic multi-threshold load management to dynamically set the transmission power of each pico eNB by adjusting the pilot power. In addition, the proposed TAeICIC utilizes a scheduling metric, proportional-fair (PF), which is the estimated throughput based on the CQI reported by a UE divided by the estimated long term average throughput achieved by the UE, to dynamically allocate an appropriate number of Almost Blank Subframes (ABSs) in each ABS period in a macro eNB so as to mitigate the interference from the macro eNB to its adjacent pico eNBs.

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43

Chen, Yen-Tsang, and 陳彥蒼. "Pilot Design for Inter-cell Interference Mitigation and Handover Decision Scheme Based on Zadoff-Chu Sequence in OFDM Systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/98823029599356874315.

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碩士
國立臺灣大學
電信工程學研究所
99
Orthogonal frequency division multiplexing (OFDM) has been widely considered to be adopted in the future wideband wireless communication systems including the Long-Term Evolution (LTE) because it has high spectral efficiency and can avoid intra-cell interference. The cellular mobile communication network based on orthogonal frequency division multiplexing access (OFDMA) also can achieve frequency reuse of one, which means that all cells in the system can use the same frequency band to serve each own users. In OFDM systems the orthogonality among subcarriers is critically demanded. Although some factors like carrier frequency and phase shift will result in inter-carrier interference, it can be depressed through advanced wireless signal processing algorithm in the physical layer. Therefore, it is thought that intra-cell interference is very small in OFDM systems. The major interference which affects the system performance is the inter-cell interference (ICI). Channel estimation is an important issue in OFDM systems. Pilot sequences are often multiplexed into the data to estimate the wireless channel gain. Both pilot sequences and their placement can affect the mean square error (MSE) of the least squares (LS) channel estimation. In order to make neighboring cells use the same frequency band to serve its own users and in the meanwhile mitigate the inter-cell interference, we choose Zadoff-Chu sequences as pilot design since its cross-correlation has good orthogonal property. Therefore, assigning neighboring cells different and orthogonal Zadoff-Chu sequences can mitigate the ICI efficiently and improve the downlink and uplink transmission performance between the base station and the users. Besides, we consider that the user located at the crossover area of multiple base station coverage can be seriously interfered with the interferers in other cells in the uplink; as a result, the serving base station can not demodulate the user’s signal correctly and excessive uplink transmission errors will result poor Quality of Service (QoS). To solve this problem, we propose a handover decision scheme, where we use the cross-correlation property of Zadoff-Chu sequences to estimate interference power seen by each neighboring base station. Then the serving base station will provide interference information of each neighboring base station to the user. The user can select the target base station which has least interference as the serving base station.

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44

Gong, Ming. "CoMP Aware Radio Resource Management in Integrated PON-OFDM Network." Thesis, 2012. http://hdl.handle.net/10012/7008.

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Radio resource management (RRM) is an important component of a mobile wireless network that efficiently utilizes the limited radio resources such as spectrum, transmission power, and network infrastructure. Unfortunately, current RRM schemes do not support cooperative multiple point (CoMP), a promising technology that extends coverage, increases capacity, and improves the spectral efficiency of the next generation broadband network, i.e., 4G network. Specifically, to coordinate with CoMP, a RRM scheme should be aware of three main properties of CoMP - cooperative transmitting information, coordinated scheduling transmission, and single interference noise ratio (SINR) improvement. However, few of the existing RRM schemes consider these properties, since they were designed based on the conventional mobile data networks without CoMP technology. In this dissertation, I present a series of new CoMP aware RRM schemes for ensuring users' throughput and maximizing network capacity in an integrated PON-OFDM network, which is a norm of the 4G network and can best implement the CoMP technology. I call the PON-OFDM network with CoMP a CoMP Network (CoMPNet). I provide two classes of RRM schemes for two practical CoMP technologies, cooperative transmission (CT) and coordinated scheduling (CoS), respectively. In the first class, I propose two groups of RRM schemes using the CT technology. In the first group, three OFDM-TDMA based RRM schemes are designed for three different users' moving speeds. The objective of these schemes is to minimize time slot consumption. The RRM schemes in the third group are contrived for an OFDM-FDMA based CoMPNet. I provide four linear programming (LP) based optimal schemes, one for minimizing bandwidth usage, one for minimizing transmission power consumption, and two for balancing resource costs. An optimized resource allocation solution can be obtained by flexibly choosing one of the schemes according to network load. In the second class, I present a sub-optimal RRM scheme for an OFDM-FDMA based CoMPNet. The CoS technology is applied for ICI mitigation. I formulate the system optimal task into constrained optimization problems for maximizing network capacity. To improve the computation efficiency, fast yet effective heuristic schemes are introduced for divide-and-conquer. The proposed heuristic schemes are featured by CoS based timeslots/subcarriers assignment mechanisms, which are further incorporated with intelligent power control schemes. Through simulations, I study the proposed RRM schemes performances and discuss the effect of the CoMP technology. The performance benefits of CoMP on bandwidth saving and capacity increasing are shown by comparing the new schemes with the conventional schemes without CoMP.

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45

Odeh, N. "Resource allocation for multi-cell OFDMA based cooperative relay network." Thesis, 2014. http://hdl.handle.net/10453/29238.

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University of Technology, Sydney. Faculty of Engineering and Information Technology.
Cooperative communications is emerging as an important area within the field of wireless communication systems. The fundamental idea is that intermediary nodes, called relay stations (RSs), who are neither the data source nor destination, are used to assist in communication between sender and receiver. In order to maximise their performance, networks which employ RSs require a new resource allocation and optimisation technique, which takes the RSs into account as a new resource. Several proposals have been presented for the purpose of optimising the distribution of available resources between users. These proposals were developed based on various network scenarios and assumptions. In most cases, impractical assumptions such as; inter-cell interference (ICI) free and full availability of channel state information (CSI) were considered. However, the need for more robust, fair and practical resource allocation algorithms motivated us to study the resource allocation algorithm for OFDMA based cooperative relay networks with more realistic assumptions. This thesis focuses on the resource allocation for the uplink OFDMA based cooperative relay networks. Multiple cells were considered, each composed of a single base station (destination), multiple amplify and forward (AF) relay stations and multiple subscriber stations (sources). The effects of inter-cell interference (ICI) have been considered to optimise the subcarrier allocation with low complexity. The optimisation problem aims to maximise the sum rate of all sources while maintaining a satisfactory degree of fairness amongst them. Furthermore, a utility based resource allocation algorithm has been developed assuming full and partial channel state information for the interference limited OFDMA-based cooperative relay network. In the proposed algorithm, relay selection is initially performed based on the level of ICI. Then, subcarrier allocation is performed on the basis of maximum achieved utility under the assumption of equal power allocation. Finally, based on the amount of ICI, a modified waterfilling power distribution algorithm is proposed and used to optimise the subcarrier power allocation across the allocated set of subcarriers. This thesis also investigates the impact of the relay-to-destination channel gain on subcarrier allocation for uplink OFDMA based cooperative relay networks using multiple amplify-and- forward (AF) relaying protocols. The closed form outage probability is derived for the system under partial channel state information (PCSI) and considering the presence of inter-cell interference (ICI). The proposed resource allocation algorithms as well as the mathematical analysis were validated through computer simulations and the results were presented for each chapter. The results show that, compared to conventional algorithms, the proposed algorithms significantly improve system performance in terms of total sum data rate, outage probability, complexity and fairness.

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Dissertations / Theses on the topic 'Inter-cell interference'

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