406 research outputs found
Massive MIMO is a Reality -- What is Next? Five Promising Research Directions for Antenna Arrays
Massive MIMO (multiple-input multiple-output) is no longer a "wild" or
"promising" concept for future cellular networks - in 2018 it became a reality.
Base stations (BSs) with 64 fully digital transceiver chains were commercially
deployed in several countries, the key ingredients of Massive MIMO have made it
into the 5G standard, the signal processing methods required to achieve
unprecedented spectral efficiency have been developed, and the limitation due
to pilot contamination has been resolved. Even the development of fully digital
Massive MIMO arrays for mmWave frequencies - once viewed prohibitively
complicated and costly - is well underway. In a few years, Massive MIMO with
fully digital transceivers will be a mainstream feature at both sub-6 GHz and
mmWave frequencies. In this paper, we explain how the first chapter of the
Massive MIMO research saga has come to an end, while the story has just begun.
The coming wide-scale deployment of BSs with massive antenna arrays opens the
door to a brand new world where spatial processing capabilities are
omnipresent. In addition to mobile broadband services, the antennas can be used
for other communication applications, such as low-power machine-type or
ultra-reliable communications, as well as non-communication applications such
as radar, sensing and positioning. We outline five new Massive MIMO related
research directions: Extremely large aperture arrays, Holographic Massive MIMO,
Six-dimensional positioning, Large-scale MIMO radar, and Intelligent Massive
MIMO.Comment: 20 pages, 9 figures, submitted to Digital Signal Processin
3D video transmission over LTE
This thesis presents a research work on quality of experience in 3D video transmission
over LTE networks. The objective is to study the state-of-art of LTE and 3D video,
described in the scientific literature, and to quantify the user quality of experience
(QoE) during a simulated LTE transmission.
The work will start by a study of the University of Wien “LTE-A System Simulator”
and its capabilities. In addition, different scenarios with various users equipment (UEs)
and base stations (eNodeBs) densities will be configured and simulated in order to
obtain the frame-by-frame Block Error Rate (BLER) values experienced by different
UEs.
Once obtained, the Block Error Rate frames will be converted to packet level error
traces, which will be used to introduce erasures and corruptions into the packetized 3D
video bitstream.
The corrupted encoded video stream will be decoded using an error-concealment
capable video decoder and the decoded/recovered video quality (QoE) will be estimated
based on the Structural Similarity Index of the recovered video.
Finally, the QoE results for the different system configurations will allow classifying
the severity of the QoE degradations due to transmission losses, through inferring the
relationship between those system parameters and the achievable QoE.Esta dissertação apresenta um trabalho de investigação sobre a qualidade de experiência
numa transmissão de vídeo 3D sobre redes LTE. O objectivo é estudar o estado-da-arte
no que respeita a rede LTE e vídeo 3D, descrito na literatura científica, e obter a
qualidade de experiência de usuário (QoE) durante uma simulação de transmissão LTE.
O trabalho começará por um estudo do University of Wien “LTE-A System Simulator”
e as suas capacidades. Para este efeito, vão ser configurados diferentes cenários com
distintas densidades de utilizadores (UEs) e estações base (eNodeBs), com o fim de
obter a taxa de erros do bloco (BLER) experimentada por diferentes utilizadores.
Depois de obter esta taxa, as tramas da taxa de erros do bloco (BLER) serão convertidas
em tramas de nível de erro de pacotes, que vão ser usadas para adicionar corrupções de
bit em ficheiros de vídeo 3D.
O fluxo de vídeo codificado e corrompido será descodificado usando um descodificador
de vídeo e a qualidade do vídeo recuperado vai ser calculada com base no Índice de
Similitude Estrutural.
Finalmente, os resultados de QoE para as diferentes configurações do sistema
permitirão classificar o nível das degradações de QoE devido a perdas de transmissão,
por meio de inferir a relação entre os parâmetros do sistema e a QoE obtida.Ingeniería de Telecomunicació
Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks
Conventional cellular wireless networks were designed with the purpose of
providing high throughput for the user and high capacity for the service
provider, without any provisions of energy efficiency. As a result, these
networks have an enormous Carbon footprint. In this paper, we describe the
sources of the inefficiencies in such networks. First we present results of the
studies on how much Carbon footprint such networks generate. We also discuss
how much more mobile traffic is expected to increase so that this Carbon
footprint will even increase tremendously more. We then discuss specific
sources of inefficiency and potential sources of improvement at the physical
layer as well as at higher layers of the communication protocol hierarchy. In
particular, considering that most of the energy inefficiency in cellular
wireless networks is at the base stations, we discuss multi-tier networks and
point to the potential of exploiting mobility patterns in order to use base
station energy judiciously. We then investigate potential methods to reduce
this inefficiency and quantify their individual contributions. By a
consideration of the combination of all potential gains, we conclude that an
improvement in energy consumption in cellular wireless networks by two orders
of magnitude, or even more, is possible.Comment: arXiv admin note: text overlap with arXiv:1210.843
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