2,754 research outputs found
Green Networking in Cellular HetNets: A Unified Radio Resource Management Framework with Base Station ON/OFF Switching
In this paper, the problem of energy efficiency in cellular heterogeneous
networks (HetNets) is investigated using radio resource and power management
combined with the base station (BS) ON/OFF switching. The objective is to
minimize the total power consumption of the network while satisfying the
quality of service (QoS) requirements of each connected user. We consider the
case of co-existing macrocell BS, small cell BSs, and private femtocell access
points (FAPs). Three different network scenarios are investigated, depending on
the status of the FAPs, i.e., HetNets without FAPs, HetNets with closed FAPs,
and HetNets with semi-closed FAPs. A unified framework is proposed to
simultaneously allocate spectrum resources to users in an energy efficient
manner and switch off redundant small cell BSs. The high complexity dual
decomposition technique is employed to achieve optimal solutions for the
problem. A low complexity iterative algorithm is also proposed and its
performances are compared to those of the optimal technique. The particularly
interesting case of semi-closed FAPs, in which the FAPs accept to serve
external users, achieves the highest energy efficiency due to increased degrees
of freedom. In this paper, a cooperation scheme between FAPs and mobile
operator is also investigated. The incentives for FAPs, e.g., renewable energy
sharing and roaming prices, enabling cooperation are discussed to be considered
as a useful guideline for inter-operator agreements.Comment: 15 pages, 9 Figures, IEEE Transactions on Vehicular Technology 201
Green Cellular Networks: A Survey, Some Research Issues and Challenges
Energy efficiency in cellular networks is a growing concern for cellular
operators to not only maintain profitability, but also to reduce the overall
environment effects. This emerging trend of achieving energy efficiency in
cellular networks is motivating the standardization authorities and network
operators to continuously explore future technologies in order to bring
improvements in the entire network infrastructure. In this article, we present
a brief survey of methods to improve the power efficiency of cellular networks,
explore some research issues and challenges and suggest some techniques to
enable an energy efficient or "green" cellular network. Since base stations
consume a maximum portion of the total energy used in a cellular system, we
will first provide a comprehensive survey on techniques to obtain energy
savings in base stations. Next, we discuss how heterogeneous network deployment
based on micro, pico and femto-cells can be used to achieve this goal. Since
cognitive radio and cooperative relaying are undisputed future technologies in
this regard, we propose a research vision to make these technologies more
energy efficient. Lastly, we explore some broader perspectives in realizing a
"green" cellular network technologyComment: 16 pages, 5 figures, 2 table
Energy efficient hybrid satellite terrestrial 5G networks with software defined features
In order to improve the manageability and adaptability
of future 5G wireless networks, the software orchestration mechanism,
named software defined networking (SDN) with Control
and User plane (C/U-plane) decoupling, has become one of the
most promising key techniques. Based on these features, the hybrid
satellite terrestrial network is expected to support flexible
and customized resource scheduling for both massive machinetype-
communication (MTC) and high-quality multimedia requests
while achieving broader global coverage, larger capacity and lower
power consumption. In this paper, an end-to-end hybrid satellite
terrestrial network is proposed and the performance metrics,
e. g., coverage probability, spectral and energy efficiency (SE and
EE), are analysed in both sparse networks and ultra-dense networks.
The fundamental relationship between SE and EE is investigated,
considering the overhead costs, fronthaul of the gateway
(GW), density of small cells (SCs) and multiple quality-ofservice
(QoS) requirements. Numerical results show that compared
with current LTE networks, the hybrid system with C/U split
can achieve approximately 40% and 80% EE improvement in
sparse and ultra-dense networks respectively, and greatly enhance
the coverage. Various resource management schemes, bandwidth
allocation methods, and on-off approaches are compared, and the
applications of the satellite in future 5G networks with software
defined features are proposed
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
Open Cell-less Network Architecture and Radio Resource Management for Future Wireless Communication Systems
In recent times, the immense growth of wireless traffic data generated from massive mobile
devices, services, and applications results in an ever-increasing demand for huge
bandwidth and very low latency, with the future networks going in the direction of achieving
extreme system capacity and ultra reliable low latency communication (URLLC). Several
consortia comprising major international mobile operators, infrastructure manufacturers,
and academic institutions are working to develop and evolve the current generation
of wireless communication systems, i.e., fifth generation (5G) towards a sixth generation
(6G) to support improved data rates, reliability, and latency. Existing 5G networks are
facing the latency challenges in a high-density and high-load scenario for an URLLC network
which may coexist with enhanced mobile broadband (eMBB) services. At the same
time, the evolution of mobile communications faces the important challenge of increased
network power consumption. Thus, energy efficient solutions are expected to be deployed
in the network in order to reduce power consumption while fulfilling user demands for
various user densities. Moreover, the network architecture should be dynamic according
to the new use cases and applications. Also, there are network migration challenges for
the multi-architecture coexistence networks.
Recently, the open radio access network (O-RAN) alliance was formed to evolve
RANs with its core principles being intelligence and openness. It aims to drive the mobile
industry towards an ecosystem of innovative, multi-vendor, interoperable, and autonomous
RAN, with reduced cost, improved performance and greater agility. However,
this is not standardized yet and still lacks interoperability. On the other hand, the cell-less
radio access network (RAN) was introduced to boost the system performance required for
the new services. However, the concept of cell-less RAN is still under consideration from
the deployment point of view with the legacy cellular networks. The virtualization, centralization and cooperative communication which enables the cell-less RAN can further
benefit from O-RAN based architecture.
This thesis addresses the research challenges facing 5G and beyond networks towards
6G networks in regard to new architectures, spectral efficiency, latency, and energy efficiency.
Different system models are stated according to the problem and several solution
schemes are proposed and developed to overcome these challenges. This thesis
contributes as follows. Firstly, the cell-less technology is proposed to be implemented
through an Open RAN architecture, which could be supervised with the near real-time
RAN intelligent controller (near-RT-RIC). The cooperation is enabled for intelligent and
smart resource allocation for the entire RAN. Secondly, an efficient radio resource optimization
mechanism is proposed for the cell-less architecture to improve the system
capacity of the future 6G networks. Thirdly, an optimized and novel resource scheduling
scheme is presented that reduces latency for the URLLC users in an efficient resource
utilization manner to support scenarios with high user density. At the same time, this radio
resource management (RRM) scheme, while minimizing the latency, also overcomes
another important challenge of eMBB users, namely the throughput of those who coexist
in such a highly loaded scenario with URLLC users. Fourthly, a novel energy-efficiency
enhancement scheme, i.e., (3 × E) is designed to increase the transmission rate per energy
unit, with stable performance within the cell-less RAN architecture. Our proposed
(3 × E) scheme activates two-step sleep modes (i.e., certain phase and conditional phase)
through the intelligent interference management for temporarily switching access points
(APs) to sleep, optimizing the network energy efficiency (EE) in highly loaded scenarios,
as well as in scenarios with lower load. Finally, a multi-architecture coexistence (MACO)
network model is proposed to enable inter-connection of different architectures through
coexistence and cooperation logical switches in order to enable smooth deployment of a
cell-less architecture within the legacy networks.
The research presented in this thesis therefore contributes new knowledge in the cellless
RAN architecture domain of the future generation wireless networks and makes important
contributions to this field by investigating different system models and proposing
solutions to significant issues.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidenta: Matilde Pilar Sánchez Fernández.- Secretario: Alberto Álvarez Polegre.- Vocal: José Francisco Monserrat del Rí
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