209 research outputs found
Enhanced Inter-Cell Interference Coordination Challenges in Heterogeneous Networks
3GPP LTE-Advanced has started a new study item to investigate Heterogeneous
Network (HetNet) deployments as a cost effective way to deal with the
unrelenting traffic demand. HetNets consist of a mix of macrocells, remote
radio heads, and low-power nodes such as picocells, femtocells, and relays.
Leveraging network topology, increasing the proximity between the access
network and the end-users, has the potential to provide the next significant
performance leap in wireless networks, improving spatial spectrum reuse and
enhancing indoor coverage. Nevertheless, deployment of a large number of small
cells overlaying the macrocells is not without new technical challenges. In
this article, we present the concept of heterogeneous networks and also
describe the major technical challenges associated with such network
architecture. We focus in particular on the standardization activities within
the 3GPP related to enhanced inter-cell interference coordination.Comment: 12 pages, 4 figures, 2 table
Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks
Soaring capacity and coverage demands dictate that future cellular networks
need to soon migrate towards ultra-dense networks. However, network
densification comes with a host of challenges that include compromised energy
efficiency, complex interference management, cumbersome mobility management,
burdensome signaling overheads and higher backhaul costs. Interestingly, most
of the problems, that beleaguer network densification, stem from legacy
networks' one common feature i.e., tight coupling between the control and data
planes regardless of their degree of heterogeneity and cell density.
Consequently, in wake of 5G, control and data planes separation architecture
(SARC) has recently been conceived as a promising paradigm that has potential
to address most of aforementioned challenges. In this article, we review
various proposals that have been presented in literature so far to enable SARC.
More specifically, we analyze how and to what degree various SARC proposals
address the four main challenges in network densification namely: energy
efficiency, system level capacity maximization, interference management and
mobility management. We then focus on two salient features of future cellular
networks that have not yet been adapted in legacy networks at wide scale and
thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and
device-to-device (D2D) communications. After providing necessary background on
CoMP and D2D, we analyze how SARC can particularly act as a major enabler for
CoMP and D2D in context of 5G. This article thus serves as both a tutorial as
well as an up to date survey on SARC, CoMP and D2D. Most importantly, the
article provides an extensive outlook of challenges and opportunities that lie
at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201
Optimisation de la gestion des interférences inter-cellulaires et de l'attachement des mobiles dans les réseaux cellulaires LTE
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 usersâ 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.Conduit par une croissance exponentielle dans les appareils mobiles et une augmentation continue de la consommation individuelle des donnĂ©es, le trafic de donnĂ©es mobiles a augmentĂ© de 4000 fois au cours des 10 derniĂšres annĂ©es et prĂšs de 400millions fois au cours des 15 derniĂšres annĂ©es. Les rĂ©seaux cellulaires homogĂšnes rencontrent de plus en plus de difficultĂ©s Ă gĂ©rer lâĂ©norme trafic de donnĂ©es mobiles et Ă assurer un dĂ©bit plus Ă©levĂ© et une meilleure qualitĂ© dâexpĂ©rience pour les utilisateurs.Ces difficultĂ©s sont essentiellement liĂ©es au spectre disponible et Ă la capacitĂ© du rĂ©seau.Lâindustrie de tĂ©lĂ©communication doit relever ces dĂ©fis et en mĂȘme temps doit garantir un modĂšle Ă©conomique pour les opĂ©rateurs qui leur permettra de continuer Ă investir pour rĂ©pondre Ă la demande croissante et rĂ©duire lâempreinte carbone due aux communications mobiles. Les rĂ©seaux cellulaires hĂ©tĂ©rogĂšnes (HetNets), composĂ©s de stations de base macro et de diffĂ©rentes stations de base de faible puissance,sont considĂ©rĂ©s comme la solution clĂ© pour amĂ©liorer lâefficacitĂ© spectrale par unitĂ© de surface et pour Ă©liminer les trous de couverture. Dans de tels rĂ©seaux, il est primordial dâattacher intelligemment les utilisateurs aux stations de base et de bien gĂ©rer les interfĂ©rences afin de gagner en performance. Comme la diffĂ©rence de puissance dâĂ©mission est importante entre les grandes et petites cellules, lâassociation habituelle des mobiles aux stations de bases en se basant sur le signal le plus fort, nâest plus adaptĂ©e dans les HetNets. Une technique basĂ©e sur des offsets individuelles par cellule Offset(CIO) est donc nĂ©cessaire afin dâĂ©quilibrer la charge entre les cellules et dâaugmenter lâattraction des petites cellules (SC) par rapport aux cellules macro (MC). Cette offset est ajoutĂ©e Ă la valeur moyenne de la puissance reçue du signal de rĂ©fĂ©rence(RSRP) mesurĂ©e par le mobile et peut donc induire Ă un changement dâattachement vers diffĂ©rents eNodeB. Comme les stations de bases dans les rĂ©seaux cellulaires LTE utilisent les mĂȘmes sous-bandes de frĂ©quences, les mobiles peuvent connaĂźtre une forte interfĂ©rence intercellulaire, en particulier en bordure de cellules. Par consĂ©quent, il est primordial de coordonner lâallocation des ressources entre les cellules et de minimiser lâinterfĂ©rence entre les cellules. Pour attĂ©nuer la forte interfĂ©rence intercellulaire, les ressources, en termes de temps, frĂ©quence et puissance dâĂ©mission, devraient ĂȘtre allouĂ©s efficacement. Un modĂšle pour chaque dimension est calculĂ© pour permettre en particulier aux utilisateurs en bordure de cellule de bĂ©nĂ©ficier dâun dĂ©bit plus Ă©levĂ© et dâune meilleure qualitĂ© de lâexpĂ©rience. Lâoptimisation de tous ces paramĂštres peut Ă©galement offrir un gain en consommation dâĂ©nergie. Dans cette thĂšse, nous proposons une solution dynamique polyvalente effectuant une optimisation de lâattachement des mobiles aux stations de base et de lâallocation des ressources dans les rĂ©seaux cellulaires LTE maximisant une fonction dâutilitĂ© du rĂ©seau qui peut ĂȘtre choisie de maniĂšre adĂ©quate.Notre solution, basĂ©e sur la thĂ©orie des jeux, permet de calculer les meilleures valeurs pour lâoffset individuelle par cellule (CIO) et pour les niveaux de puissance Ă appliquer au niveau temporel et frĂ©quentiel pour chaque cellule. Nous prĂ©sentons des rĂ©sultats des simulations effectuĂ©es pour illustrer le gain de performance important apportĂ© par cette optimisation. Nous obtenons une significative hausse dans le dĂ©bit moyen et le dĂ©bit des utilisateurs en bordure de cellule avec 40 % et 55 % de gains respectivement. En outre, on obtient un gain important en Ă©nergie. Ce travail aborde des dĂ©fis pour lâindustrie des tĂ©lĂ©coms et en tant que tel, un prototype de lâoptimiseur a Ă©tĂ© implĂ©mentĂ© en se basant sur un trafic HetNets Ă©mulĂ©
Energy efficiency in heterogeneous wireless access networks
In this article, we bring forward the important aspect of energy savings in wireless access networks. We specifically focus on the energy saving opportunities in the recently evolving heterogeneous networks (HetNets), both Single- RAT and Multi-RAT. Issues such as sleep/wakeup cycles and interference management are discussed for co-channel Single-RAT HetNets. In addition to that, a simulation based study for LTE macro-femto HetNets is presented, indicating the need for dynamic energy efficient resource management schemes. Multi-RAT HetNets also come with challenges such as network integration, combined resource management and network selection. Along with a discussion on these challenges, we also investigate the performance of the conventional WLAN-first network selection mechanism in terms of energy efficiency (EE) and suggest that EE can be improved by the application of intelligent call admission control policies
Generalized Coordinated Multipoint Framework for 5G and Beyond
The characteristic feature of 5G is the diversity of its services for
different user needs. However, the requirements for these services are
competing in nature, which impresses the necessity of a coordinated and
flexible network architecture. Although coordinated multipoint (CoMP) systems
were primarily proposed to improve the cell edge performance in 4G, their
collaborative nature can be leveraged to support the diverse requirements and
enabling technologies of 5G and beyond networks. To this end, we propose
generalization of CoMP to a proactive and efficient resource utilization
framework capable of supporting different user requirements such as
reliability, latency, throughput, and security while considering network
constraints. This article elaborates on the multiple aspects, inputs, and
outputs of the generalized CoMP (GCoMP) framework. Apart from user
requirements, the GCoMP decision mechanism also considers the CoMP scenario and
network architecture to decide upon outputs such as CoMP technique or
appropriate coordinating clusters. To enable easier understanding of the
concept, popular use cases, such as vehicle-to-everything (V2X) communication
and eHealth, are studied. Additionally, interesting challenges and open areas
in GCoMP are discussed.Comment: 11 pages, 7 figure
Towards UAV Assisted 5G Public Safety Network
Ensuring ubiquitous mission-critical public safety communications (PSC) to all the first responders in the public safety network is crucial at an emergency site. The first responders heavily rely on mission-critical PSC to save lives, property, and national infrastructure during a natural or human-made emergency. The recent advancements in LTE/LTE-Advanced/5G mobile technologies supported by unmanned aerial vehicles (UAV) have great potential to revolutionize PSC.
However, limited spectrum allocation for LTE-based PSC demands improved channel capacity and spectral efficiency. An additional challenge in designing an LTE-based PSC network is achieving at least 95% coverage of the geographical area and human population with broadband rates. The coverage requirement and efficient spectrum use in the PSC network can be realized through the dense deployment of small cells (both terrestrial and aerial). However, there are several challenges with the dense deployment of small cells in an air-ground heterogeneous network (AG-HetNet). The main challenges which are addressed in this research work are integrating UAVs as both aerial user and aerial base-stations, mitigating inter-cell interference, capacity and coverage enhancements, and optimizing deployment locations of aerial base-stations.
First, LTE signals were investigated using NS-3 simulation and software-defined radio experiment to gain knowledge on the quality of service experienced by the user equipment (UE). Using this understanding, a two-tier LTE-Advanced AG-HetNet with macro base-stations and unmanned aerial base-stations (UABS) is designed, while considering time-domain inter-cell interference coordination techniques. We maximize the capacity of this AG-HetNet in case of a damaged PSC infrastructure by jointly optimizing the inter-cell interference parameters and UABS locations using a meta-heuristic genetic algorithm (GA) and the brute-force technique. Finally, considering the latest specifications in 3GPP, a more realistic three-tier LTE-Advanced AG-HetNet is proposed with macro base-stations, pico base-stations, and ground UEs as terrestrial nodes and UABS and aerial UEs as aerial nodes. Using meta-heuristic techniques such as GA and elitist harmony search algorithm based on the GA, the critical network elements such as energy efficiency, inter-cell interference parameters, and UABS locations are all jointly optimized to maximize the capacity and coverage of the AG-HetNet
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