13,801 research outputs found
Energy-efficient wireless communication
In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters
Interference Management Based on RT/nRT Traffic Classification for FFR-Aided Small Cell/Macrocell Heterogeneous Networks
Cellular networks are constantly lagging in terms of the bandwidth needed to
support the growing high data rate demands. The system needs to efficiently
allocate its frequency spectrum such that the spectrum utilization can be
maximized while ensuring the quality of service (QoS) level. Owing to the
coexistence of different types of traffic (e.g., real-time (RT) and
non-real-time (nRT)) and different types of networks (e.g., small cell and
macrocell), ensuring the QoS level for different types of users becomes a
challenging issue in wireless networks. Fractional frequency reuse (FFR) is an
effective approach for increasing spectrum utilization and reducing
interference effects in orthogonal frequency division multiple access networks.
In this paper, we propose a new FFR scheme in which bandwidth allocation is
based on RT/nRT traffic classification. We consider the coexistence of small
cells and macrocells. After applying FFR technique in macrocells, the remaining
frequency bands are efficiently allocated among the small cells overlaid by a
macrocell. In our proposed scheme, total frequency-band allocations for
different macrocells are decided on the basis of the traffic intensity. The
transmitted power levels for different frequency bands are controlled based on
the level of interference from a nearby frequency band. Frequency bands with a
lower level of interference are assigned to the RT traffic to ensure a higher
QoS level for the RT traffic. RT traffic calls in macrocell networks are also
given a higher priority compared with nRT traffic calls to ensure the low
call-blocking rate. Performance analyses show significant improvement under the
proposed scheme compared with conventional FFR schemes
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
Energy-efficient adaptive wireless network design
Energy efficiency is an important issue for mobile computers since they must rely on their batteries. We present an energy-efficient highly adaptive architecture of a network interface and novel data link layer protocol for wireless networks that provides quality of service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations are necessary to achieve energy efficiency and an acceptable quality of service. The paper provides a review of ideas and techniques relevant to the design of an energy efficient adaptive wireless networ
Transmit Power Minimization in Small Cell Networks Under Time Average QoS Constraints
We consider a small cell network (SCN) consisting of N cells, with the small
cell base stations (SCBSs) equipped with Nt \geq 1 antennas each, serving K
single antenna user terminals (UTs) per cell. Under this set up, we address the
following question: given certain time average quality of service (QoS) targets
for the UTs, what is the minimum transmit power expenditure with which they can
be met? Our motivation to consider time average QoS constraint comes from the
fact that modern wireless applications such as file sharing, multi-media etc.
allow some flexibility in terms of their delay tolerance. Time average QoS
constraints can lead to greater transmit power savings as compared to
instantaneous QoS constraints since it provides the flexibility to dynamically
allocate resources over the fading channel states. We formulate the problem as
a stochastic optimization problem whose solution is the design of the downlink
beamforming vectors during each time slot. We solve this problem using the
approach of Lyapunov optimization and characterize the performance of the
proposed algorithm. With this algorithm as the reference, we present two main
contributions that incorporate practical design considerations in SCNs. First,
we analyze the impact of delays incurred in information exchange between the
SCBSs. Second, we impose channel state information (CSI) feedback constraints,
and formulate a joint CSI feedback and beamforming strategy. In both cases, we
provide performance bounds of the algorithm in terms of satisfying the QoS
constraints and the time average power expenditure. Our simulation results show
that solving the problem with time average QoS constraints provide greater
savings in the transmit power as compared to the instantaneous QoS constraints.Comment: in Journal on Selected Areas of Communications (JSAC), 201
EVEREST IST - 2002 - 00185 : D23 : final report
Deliverable pĂşblic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version
A Novel Multiobjective Cell Switch-Off Framework for Cellular Networks
Cell Switch-Off (CSO) is recognized as a promising approach to reduce the
energy consumption in next-generation cellular networks. However, CSO poses
serious challenges not only from the resource allocation perspective but also
from the implementation point of view. Indeed, CSO represents a difficult
optimization problem due to its NP-complete nature. Moreover, there are a
number of important practical limitations in the implementation of CSO schemes,
such as the need for minimizing the real-time complexity and the number of
on-off/off-on transitions and CSO-induced handovers. This article introduces a
novel approach to CSO based on multiobjective optimization that makes use of
the statistical description of the service demand (known by operators). In
addition, downlink and uplink coverage criteria are included and a comparative
analysis between different models to characterize intercell interference is
also presented to shed light on their impact on CSO. The framework
distinguishes itself from other proposals in two ways: 1) The number of
on-off/off-on transitions as well as handovers are minimized, and 2) the
computationally-heavy part of the algorithm is executed offline, which makes
its implementation feasible. The results show that the proposed scheme achieves
substantial energy savings in small cell deployments where service demand is
not uniformly distributed, without compromising the Quality-of-Service (QoS) or
requiring heavy real-time processing
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