Optimal resource allocation in femtocell networks based on Markov modeling of interferers' activity

Femtocell networks offer a series of advantages with respect to conventional cellular networks. However, a potential massive deployment of femto-access points (FAPs) poses a big challenge in terms of interference management, which requires proper radio resource allocation techniques. In this article, we propose alternative optimal power/bit allocation strategies over a time-frequency frame based on a statistical modeling of the interference activity. Given the lack of knowledge of the interference activity, we assume a Bayesian approach that provides the optimal allocation, conditioned to periodic spectrum sensing, and estimation of the interference activity statistical parameters. We consider first a single FAP accessing the radio channel in the presence of a dynamical interference environment. Then, we extend the formulation to a multi-FAP scenario, where nearby FAP's react to the strategies of the other FAP's, still within a dynamical interference scenario. The multi-user case is first approached using a strategic non-cooperative game formulation. Then, we propose a coordination game based on the introduction of a pricing mechanism that exploits the backhaul link to enable the exchange of parameters (prices) among FAP's

Project Final Report – FREEDOM ICT-248891

This document is the final publishable summary report of the objective and work carried out within the European Project FREEDOM, ICT-248891.This document is the final publishable summary report of the objective and work carried out within the European Project FREEDOM, ICT-248891.Preprin

Gestion dynamique de ressources appliquée aux réseaux cellulaires avec interférence

The aim of this thesis is to design, implement and evaluate practical cross-layer algorithms. We focus on LTE and post-LTE uncoordinated networks where interference is a key issue given the new traffic patterns. The goal is to allocate the radio resources in an efficient way. We develop mathematical and computational interference models that allow us to understand the behavior of such networks and we apply an information-theoretic approach to different interference scenarios and traffic characteristics. We have tried to remain as close as possible to practical systems to be able to test the feasibility of the proposed techniques. The thesis deals with performance evaluation of interference scenarios in 4G networks, in particular those arising from small-cell deployments. The work in this thesis also deals with analysis of resource-allocation and incremental-redundancy based hybrid automatic repeat request (HARQ) for bursty interference (or more general time-varying channels) which allows for only partial channel state information at the transmitter. The work is then applied to practical scheduler design for LTE base stations and includes performance analysis for real LTE modems.L'objectif de cette thèse est de concevoir, implémenter et évaluer les algorithmes cross-layer pratiques. Nous nous concentrons sur la technologie LTE et les réseaux non coordonnés post-LTE où l'interférence est un enjeu majeur compte tenu des nouvelles tendances du trafic. L'objectif est d'allouer les ressources radio d'une manière efficace. Nous développons des modèles d'interférence mathématiques et informatiques qui nous permettent de comprendre le comportement de ces réseaux et nous appliquons une approche basée sur la théorie de l'information à différents scénarios d'interférence et caractéristiques du trafic. Nous avons essayé de s'approcher le plus possible de systèmes réels pour être en mesure de tester la faisabilité des techniques proposées. La thèse porte sur l'évaluation de la performance des scénarios d'interférence dans les réseaux 4G, en particulier celles qui découlent du déploiements de cellules de petite taille ("small cells"). Le travail dans cette thèse s'adresse également à l'analyse de l'allocation des ressources et la requête de répétition automatique hybride (HARQ) à redondance incrémentale pour les interférences sporadiques (de façon plus générale les canaux variables dans le temps) qui permet uniquement des informations partielles de l'état du canal à l'émetteur. Ce travail est ensuite appliquée à la conception d'ordonnanceur pour les stations de base LTE et inclut une analyse de performance pour les modems LTE réels

Performance analysis of two-tier wireless networks with dynamic traffic, backhaul constraints, and terminal mobility

(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works[EN] Over the past few years, mobile cellular networks have witnessed an enormous growth in the carried data-traffic volume. The current networks' features are not enough to cope with this traffic trend, and the concept of small cells has emerged as a feasible solution to increase the network capacity. However, the deployment of small cells introduces several technical challenges, such as the cross-tier interference between the macrocell and the small cells or the use of the subscriber landline to send the backhaul data. In this paper, an analytical model is proposed to study the impact that the user traffic dynamics, the mobility of macrocell users, the scheme chosen to associate macrocell users to the small cells, and the changing available capacity of the small-cell backhaul have on the system performance. To make the solution of the model computationally feasible, we exploit the time-scale decomposition approach. In most practical scenarios, the arrival and departure rates of traffic flows are much larger than the rate of events associated with the mobility of macrocell users. Then, flows perceive that macrocell users are still. This model is applied to identify the scheme to associate macrocell users to the small cells, which maximizes the performance perceived by the small-cell users. © 2015 IEEE.This work was supported in part by the Ministry of Economy and Competitiveness of Spain under Grant TIN2013-47272-C2-1-R. The review of this paper was coordinated by Prof. Y.-B. Lin.Bernal Mor, E.; Pla, V.; Martínez Bauset, J.; Guijarro, L. (2016). Performance analysis of two-tier wireless networks with dynamic traffic, backhaul constraints, and terminal mobility. IEEE Transactions on Vehicular Technology. 65(1):241-250. https://doi.org/10.1109/TVT.2015.2397317S24125065

Modeling and Optimization of Next-Generation Wireless Access Networks

The ultimate goal of the next generation access networks is to provide all network users, whether they are fixed or mobile, indoor or outdoor, with high data rate connectivity, while ensuring a high quality of service. In order to realize this ambitious goal, delay, jitter, error rate and packet loss should be minimized: a goal that can only be achieved through integrating different technologies, including passive optical networks, 4th generation wireless networks, and femtocells, among others. This thesis focuses on medium access control and physical layers of future networks. In this regard, the first part of this thesis discusses techniques to improve the end-to-end quality of service in hybrid optical-wireless networks. In these hybrid networks, users are connected to a wireless base station that relays their data to the core network through an optical connection. Hence, by integrating wireless and optical parts of these networks, a smart scheduler can predict the incoming traffic to the optical network. The prediction data generated herein is then used to propose a traffic-aware dynamic bandwidth assignment algorithm for reducing the end-to-end delay. The second part of this thesis addresses the challenging problem of interference management in a two-tier macrocell/femtocell network. A high quality, high speed connection for indoor users is ensured only if the network has a high signal to noise ratio. A requirement that can be fulfilled with using femtocells in cellular networks. However, since femtocells generate harmful interference to macrocell users in proximity of them, careful analysis and realistic models should be developed to manage the introduced interference. Thus, a realistic model for femtocell interference outside suburban houses is proposed and several performance measures, e.g., signal to interference and noise ratio and outage probability are derived mathematically for further analysis. The quality of service of cellular networks can be degraded by several factors. For example, in industrial environments, simultaneous fading and strong impulsive noise significantly deteriorate the error rate performance. In the third part of this thesis, a technique to improve the bit error rate of orthogonal frequency division multiplexing systems in industrial environments is presented. This system is the most widely used technology in next-generation networks, and is very susceptible to impulsive noise, especially in fading channels. Mathematical analysis proves that the proposed method can effectively mitigate the degradation caused by impulsive noise and significantly improve signal to interference and noise ratio and bit error rate, even in frequency-selective fading channels

Radio network management in cognitive LTE-Femtocell Systems

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.There is a strong uptake of femtocell deployment as small cell application platforms in the upcoming LTE networks. In such two-tier networks of LTEfemtocell base stations, a large portion of the assigned spectrum is used sporadically leading to underutilisation of valuable frequency resources. Novel spectrum access techniques are necessary to solve these current spectrum inefficiency problems. Therefore, spectrum management solutions should have the features to improve spectrum access in both temporal and spatial manner. Cognitive Radio (CR) with the Dynamic Spectrum Access (DSA) is considered to be the key technology in this research in order to increase the spectrum efficiency. This is an effective solution to allow a group of Secondary Users (SUs) to share the radio spectrum initially allocated to the Primary User (PUs) at no interference. The core aim of this thesis is to develop new cognitive LTE-femtocell systems that offer a 4G vision, to facilitate the radio network management in order to increase the network capacity and further improve spectrum access probabilities. In this thesis, a new spectrum management model for cognitive radio networks is considered to enable a seamless integration of multi-access technology with existing networks. This involves the design of efficient resource allocation algorithms that are able to respond to the rapid changes in the dynamic wireless environment and primary users activities. Throughout this thesis a variety of network upgraded functions are developed using application simulation scenarios. Therefore, the proposed algorithms, mechanisms, methods, and system models are not restricted in the considered networks, but rather have a wider applicability to be used in other technologies. This thesis mainly investigates three aspects of research issues relating to the efficient management of cognitive networks: First, novel spectrum resource management modules are proposed to maximise the spectrum access by rapidly detecting the available transmission opportunities. Secondly, a developed pilot power controlling algorithm is introduced to minimise the power consumption by considering mobile position and application requirements. Also, there is investigation on the impact of deploying different numbers of femtocell base stations in LTE domain to identify the optimum cell size for future networks. Finally, a novel call admission control mechanism for mobility management is proposed to support seamless handover between LTE and femtocell domains. This is performed by assigning high speed mobile users to the LTE system to avoid unnecessary handovers. The proposed solutions were examined by simulation and numerical analysis to show the strength of cognitive femtocell deployment for the required applications. The results show that the new system design based on cognitive radio configuration enable an efficient resource management in terms of spectrum allocation, adaptive pilot power control, and mobile handover. The proposed framework and algorithms offer a novel spectrum management for self organised LTE-femtocell architecture. Eventually, this research shows that certain architectures fulfilling spectrum management requirements are implementable in practice and display good performance in dynamic wireless environments which recommends the consideration of CR systems in LTE and femtocell networks

Review on Radio Resource Allocation Optimization in LTE/LTE-Advanced using Game Theory

Recently, there has been a growing trend toward ap-plying game theory (GT) to various engineering fields in order to solve optimization problems with different competing entities/con-tributors/players. Researches in the fourth generation (4G) wireless network field also exploited this advanced theory to overcome long term evolution (LTE) challenges such as resource allocation, which is one of the most important research topics. In fact, an efficient de-sign of resource allocation schemes is the key to higher performance. However, the standard does not specify the optimization approach to execute the radio resource management and therefore it was left open for studies. This paper presents a survey of the existing game theory based solution for 4G-LTE radio resource allocation problem and its optimization