558 research outputs found
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
Eficiência energética avançada para sistema OFDMA CoMP coordenação multiponto
Doutoramento em Engenharia EletrotécnicaThe ever-growing energy consumption in mobile networks stimulated by
the expected growth in data tra ffic has provided the impetus for mobile
operators to refocus network design, planning and deployment towards reducing
the cost per bit, whilst at the same time providing a signifi cant step
towards reducing their operational expenditure. As a step towards incorporating
cost-eff ective mobile system, 3GPP LTE-Advanced has adopted the
coordinated multi-point (CoMP) transmission technique due to its ability
to mitigate and manage inter-cell interference (ICI). Using CoMP the cell
average and cell edge throughput are boosted. However, there is room for
reducing energy consumption further by exploiting the inherent
exibility of
dynamic resource allocation protocols. To this end packet scheduler plays
the central role in determining the overall performance of the 3GPP longterm
evolution (LTE) based on packet-switching operation and provide a
potential research playground for optimizing energy consumption in future
networks. In this thesis we investigate the baseline performance for down
link CoMP using traditional scheduling approaches, and subsequently go
beyond and propose novel energy e fficient scheduling (EES) strategies that
can achieve power-e fficient transmission to the UEs whilst enabling both
system energy effi ciency gain and fairness improvement. However, ICI can
still be prominent when multiple nodes use common resources with di fferent
power levels inside the cell, as in the so called heterogeneous networks (Het-
Net) environment. HetNets are comprised of two or more tiers of cells. The
rst, or higher tier, is a traditional deployment of cell sites, often referred
to in this context as macrocells. The lower tiers are termed small cells, and
can appear as microcell, picocells or femtocells. The HetNet has attracted
signiffi cant interest by key manufacturers as one of the enablers for high
speed data at low cost. Research until now has revealed several key hurdles
that must be overcome before HetNets can achieve their full potential:
bottlenecks in the backhaul must be alleviated, as well as their seamless
interworking with CoMP. In this thesis we explore exactly the latter hurdle,
and present innovative ideas on advancing CoMP to work in synergy with
HetNet deployment, complemented by a novel resource allocation policy
for HetNet tighter interference management. As system level simulator has
been used to analyze the proposed algorithm/protocols, and results have
concluded that up to 20% energy gain can be observed.O aumento do consumo de energia nas TICs e em particular nas redes de
comunicação móveis, estimulado por um crescimento esperado do tráfego de
dados, tem servido de impulso aos operadores m oveis para reorientarem os
seus projectos de rede, planeamento e implementa ção no sentido de reduzir
o custo por bit, o que ao mesmo tempo possibilita um passo signicativo no
sentido de reduzir as despesas operacionais. Como um passo no sentido de
uma incorporação eficaz em termos destes custos, o sistema móvel 3GPP
LTE-Advanced adoptou a técnica de transmissão Coordenação Multi-Ponto
(identificada na literatura com a sigla CoMP) devido à sua capacidade de
mitigar e gerir Interferência entre Células (sigla ICI na literatura). No entanto
a ICI pode ainda ser mais proeminente quando v arios n os no interior
da célula utilizam recursos comuns com diferentes níveis de energia,
como acontece nos chamados ambientes de redes heterogéneas (sigla Het-
Net na literatura). As HetNets são constituídas por duas ou mais camadas
de células. A primeira, ou camada superiora, constitui uma implantação
tradicional de sítios de célula, muitas vezes referidas neste contexto como
macrocells. Os níveis mais baixos são designados por células pequenas, e
podem aparecer como microcells, picocells ou femtocells. A HetNet tem
atra do grande interesse por parte dos principais fabricantes como sendo
facilitador para transmissões de dados de alta velocidade a baixo custo. A
investigação tem revelado at e a data, vários dos principais obstáculos que
devem ser superados para que as HetNets possam atingir todo o seu potencial:
(i) os estrangulamentos no backhaul devem ser aliviados; (ii) bem
como sua perfeita interoperabilidade com CoMP. Nesta tese exploramos
este ultimo constrangimento e apresentamos ideias inovadoras em como a
t ecnica CoMP poder a ser aperfeiçoada por forma a trabalhar em sinergia
com a implementação da HetNet, complementado ainda com uma nova
perspectiva na alocação de recursos rádio para um controlo e gestão mais
apertado de interferência nas HetNets. Com recurso a simulação a níível de
sistema para analisar o desempenho dos algoritmos e protocolos propostos,
os resultados obtidos concluíram que ganhos at e a ordem dos 20% poderão
ser atingidos em termos de eficiência energética
LTE-verkon suorituskyvyn parantaminen CDMA2000:sta LTE:hen tehdyn muutoksen jälkeen
CDMA2000 technology has been widely used on 450 MHz band. Recently the equipment availability and improved performance offered by LTE has started driving the operators to migrate their networks from CDMA2000 to LTE. The migration may cause the network performance to be in suboptimal state.
This thesis presents four methods to positively influence LTE network performance after CDMA2000 to LTE migration, especially on 450 MHz band. Furthermore, three of the four presented methods are evaluated in a live network. The measured three methods were cyclic prefix length, handover parameter optimization and uplink coordinated multipoint (CoMP) transmission. The objective was to determine the effectiveness of each method. The research methods included field measurements and network KPI collection.
The results show that normal cyclic prefix length is enough for LTE450 although the cell radius may be up to 50km. Only special cases exist where cyclic prefix should be extended. Operators should consider solving such problems individually instead of widely implementing extended cyclic prefix.
Handover parameter optimization turned out to be an important point of attention after CDMA2000 to LTE migration. It was observed that if the handover parameters are not concerned, significant amount of unnecessary handovers may happen. It was evaluated that about 50% of the handovers in the network were unnecessary in the initial situation. By adjusting the handover parameter values 47,28 % of the handovers per user were removed and no negative effects were detected.
Coordinated multipoint transmission has been widely discussed to be an effective way to improve LTE network performance, especially at the cell edges. Many challenges must be overcome before it can be applied to downlink. Also, implementing it to function between cells in different eNBs involve challenges. Thus, only intra-site uplink CoMP transmission was tested. The results show that the performance improvements were significant at the cell edges as theory predicted.CDMA2000 teknologiaa on laajalti käytetty 450 MHz:n taajuusalueella. Viime aikoina LTE:n tarjoamat halvemmat laitteistot ja parempi suorituskyky ovat kannustaneet operaattoreita muuttamaan verkkoaan CDMA2000:sta LTE:hen. Kyseinen muutos saattaa johtaa epäoptimaaliseen tilaan verkon suorituskyvyn kannalta.
Tämä työ esittelee neljä menetelmää, joilla voidaan positiivisesti vaikuttaa LTE-verkon suorituskykyyn CDMA2000:ste LTE:hen tehdyn muutoksen jälkeen erityisesti 450 MHz:n taajuusalueella. Kolmea näistä menetelmistä arvioidaan tuotantoverkossa. Nämä kolme menetelmää ovat suojavälin pituus, solunvaihtoparametrien optimointi ja ylälinkin koordinoitu monipistetiedonsiirto. Tavoite oli määrittää kunkin menetelmän vaikutus. Tutkimusmenetelmiin kuului kenttämittaukset ja verkon suorituskykymittareiden analyysi.
Tutkimustulosten perusteella voidaan sanoa, että normaali suojaväli on riittävän pitkä LTE450:lle vaikka solujen säde on jopa 50km. Vain erikoistapauksissa tarvitaan pidennettyä suojaväliä. Operaattoreiden tulisi ratkaista tällaiset tapaukset yksilöllisesti sen sijaan, että koko verkossa käytettäisiin pidennettyä suojaväliä.
Solunvaihtoparametrien optimointi osoittautui tärkeäksi huomion aiheeksi CDMA2000:sta LTE:hen tehdyn muutoksen jälkeen. Turhia solunvaihtoja saattaa tapahtua merkittäviä määriä, mikäli parametreihin ei kiinnitetä huomiota. Lähtötilanteessa noin 50 % testiverkon solunvaihdoista arvioitiin olevan turhia. Solunvaihtoparametreja muuttamalla 47,28 % solunvaihdoista per käyttäjä saatiin poistettua ilman, että mitään haittavaikutuksia olisi huomattu.
Koordinoidun monipistetiedonsiirron on laajalti sanottu olevan tehokas tapa parantaa LTE-verkon suorituskykyä, etenkin solujen reunoilla. Monia haasteita pitää ratkaista, enne kuin sitä voidaan käyttää alalinkin tiedonsiirtoon. Lisäksi sen käyttöön eri tukiasemien solujen välillä liittyy haasteita. Tästä syystä monipistetiedonsiirtoa voitiin testata vain ylälinkin suuntaan ja vain yhden tukiaseman välisten solujen kesken. Tulokset osoittivat, että suorituskyky parani merkittävästi solun reunalla
LTE Advanced: Technology and Performance Analysis
Wireless data usage is increasing at a phenomenal rate and driving the need for continued innovations in wireless data technologies to provide more capacity and higher quality of service. In October 2009, 3rd Generation Partnership Project (3GPP) submitted LTE-Advanced to the ITU as a proposed candidate IMT-Advanced technology for which specifications could become available in 2011 through Release-10 . The aim of “LTE-Advanced” is to further enhance LTE radio access in terms of system performance and capabilities compared to current cellular systems, including the first release of LTE, with a specific goal to ensure that LTE fulfills and even surpass the requirements of “IMT-Advanced” as defined by the International Telecommunication Union (ITU-R) .
This thesis offers an introduction to the mobile communication standard known as LTE Advanced, depicting the evolution of the standard from its roots and discussing several important technologies that help it evolve to accomplishing the IMT-Advanced requirements. A short history of the LTE standard is offered, along with a discussion of its standards and performance. LTE-Advanced details include analysis on the physical layer by investigating the performance of SC-FDMA and OFDMA of LTE physical layer. The investigation is done by considering different modulation schemes (QPSK, 16QAM and 64QAM) on the basis of PAPR, BER, power spectral density (PSD) and error probability by simulating the model of SC-FDMA & OFDMA. To evaluate the performance in presence of noise, an Additive White Gaussian Noise (AWGN) channel was introduced.
A set of conclusions is derived from our results describing the effect of higher order modulation schemes on BER and error probability for both OFDMA and SC-FDMA. The power spectral densities of both the multiple access techniques (OFDMA and SC-FDMA) are calculated and result shows that the OFDMA has higher power spectral density.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format
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LTE-Advanced radio access enhancements: A survey
Long Term Evolution Advanced (LTE-Advanced) is the next step in LTE evolution and allows operators to improve network performance and service capabilities through smooth deployment of new techniques and technologies. LTE-Advanced uses some new features on top of the existing LTE standards to provide better user experience and higher throughputs. Some of the most significant features introduced in LTE-Advanced are carrier aggregation, enhancements in heterogeneous networks, coordinated multipoint transmission and reception, enhanced multiple input multiple output usage and deployment of relay nodes in the radio network. Mentioned features are mainly aimed to enhance the radio access part of the cellular networks. This survey article presents an overview of the key radio access features and functionalities of the LTE-Advanced radio access network, supported by the simulation results. We also provide a detailed review of the literature together with a very rich list of the references for each of the features. An LTE-Advanced roadmap and the latest updates and trends in LTE markets are also presented
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