507 research outputs found
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
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
Opportunities and Challenges in OFDMA-Based Cellular Relay Networks: A Radio Resource Management Perspective
The opportunities and flexibility in relay networks and orthogonal frequency-division multiple access (OFDMA) make the combination a suitable candidate network and air-interface technology for providing reliable and ubiquitous high-data-r
On the spectral-energy efficiency and rate fairness tradeoff in relay-aided cooperative OFDMA systems
In resource constrained wireless systems, achieving higher spectral efficiency (SE) and energy efficiency (EE), and greater rate fairness are conflicting objectives. Here a general framework is presented to analyze the tradeoff among these three performance metrics in cooperative OFDMA systems with decode-and-forward (DF) relaying, where subcarrier pairing and allocation, relay selection, choice of transmission strategy, and power allocation are jointly considered. In our analytical framework, rate fairness is represented utilizing -fairness model and the resource allocation problem is formulated as a multiobjective optimization (MOO) problem. We then propose a cross-layer resource allocation algorithm across application and physical layers, and further devise a heuristic algorithm to tackle the computational complexity issue. The SE-EE tradeoff is characterized as a Pareto optimal set, and the efficiency and fairness tradeoff is investigated through the price of fairness (PoF). Simulations indicate that higher fairness results in a worse SE-EE tradeoff. It is also shown imposing fairness helps to reduce the outage probability. For a fixed number of relays, by increasing circuit power, the performance of SE-EE tradeoff is degraded. Interestingly, by increasing the number of relays, although the total circuit power is increased, the SE-EE tradeoff is not necessarily degraded. This is thanks to the extra degree of freedom provided in relay selection
OFDMA-based resource allocation for wireless communication systems
Ph.DDOCTOR OF PHILOSOPH
Investigation on Evolving Single-Carrier NOMA into Multi-Carrier NOMA in 5G
© 2013 IEEE. Non-orthogonal multiple access (NOMA) is one promising technology, which provides high system capacity, low latency, and massive connectivity, to address several challenges in the fifth-generation wireless systems. In this paper, we first reveal that the NOMA techniques have evolved from single-carrier NOMA (SC-NOMA) into multi-carrier NOMA (MC-NOMA). Then, we comprehensively investigated on the basic principles, enabling schemes and evaluations of the two most promising MC-NOMA techniques, namely sparse code multiple access (SCMA) and pattern division multiple access (PDMA). Meanwhile, we consider that the research challenges of SCMA and PDMA might be addressed with the stimulation of the advanced and matured progress in SC-NOMA. Finally, yet importantly, we investigate the emerging applications, and point out the future research trends of the MC-NOMA techniques, which could be straightforwardly inspired by the various deployments of SC-NOMA
A Survey of Downlink Non-orthogonal Multiple Access for 5G Wireless Communication Networks
Accepted by ZTE CommunicationsAccepted by ZTE CommunicationsAccepted by ZTE CommunicationsAccepted by ZTE CommunicationsAccepted by ZTE CommunicationsNon-orthogonal multiple access (NOMA) has been recognized as a promising multiple access technique for the next generation cellular communication networks. In this paper, we first discuss a simple NOMA model with two users served by a single-carrier simultaneously to illustrate its basic principles. Then, a more general model with multicarrier serving an arbitrary number of users on each subcarrier is also discussed. An overview of existing works on performance analysis, resource allocation, and multiple-input multiple-output NOMA are summarized and discussed. Furthermore, we discuss the key features of NOMA and its potential research challenges
Radio resource allocation in relay based OFDMA cellular networks
PhDAdding relay stations (RS) between the base station (BS) and the mobile stations (MS) in a cellular system can extend network coverage, overcome multi-path fading and increase the capacity of the system.
This thesis considers the radio resource allocation scheme in relay based cellular networks to ensure high-speed and reliable communication. The goal of this research is to investigate user fairness, system throughput and power consumption in wireless relay networks through considering how best to manage the radio resource.
This thesis proposes a two-hop proportional fairness (THPF) scheduling scheme fair allocation, which is considered both in the first time subslot between direct link users and relay stations, and the second time subslot among relay link users.
A load based relay selection algorithm is also proposed for a fair resource allocation. The transmission mode (direct transmission mode or relay transmission mode) of each user will be adjusted based on the load of the transmission node.
Power allocation is very important for resource efficiency and system performance improvement and this thesis proposes a two-hop power allocation algorithm for energy efficiency, which adjusts the transmission power of the BS and RSs to make the data rate on the two hop links of one RS match each other.
The power allocation problem of multiple cells with inter-cell interference is studied. A new multi-cell power allocation scheme is proposed from non-cooperative game theory; this coordinates the inter-cell interference and operates in a distributed manner. The utility function can be designed for throughput improvement and user fairness respectively.
Finally, the proposed algorithms in this thesis are combined, and the system performance is evaluated. The joint radio resource allocation algorithm can achieve a very good tradeoff between throughput and user fairness, and also can significantly improve energy efficiency
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