289 research outputs found
Machine learning based heuristic BBU-RRH switching scheme for C-RAN in 5G
The immense increase in bandwidth demand by various services such as high definition video streaming, online gaming, and virtual reality has made it increasingly challenging for operators to provide satisfactory services to the end users while making a profit. Cloud Radio Access Network (C-RAN) is a new architecture that has been proposed to facilitate the mobile networks' ability to meet the increase in bandwidth demand. C-RAN consists of three parts, namely Remote Radio Head (RRH), the front haul link, and Baseband Processing Units (BBU) pool. Many RRHs are associated with one BBU pool, and all RRHs within the pool are logically connected to every BBU in the pool. Thus, a BBU-RRH switching algorithm needs to be developed as it is able to enhance the performance of such architecture while managing the resource efficiently. This work mainly focuses on developing a traffic profile prediction-based BBU-RRH switching algorithm using a real life dataset. In the literature, there are related works that have proposed algorithms to achieve this purpose. However some of the existing algorithms suffer from high switching complexity while others fall short in QoS provision. Therefore, this work develops a BBU-RRH algorithm that to enhance the QoS while reducing the switching complexity, with the aid of machine learning techniques. The algorithm developed consists of three parts. The first part consists of an efficient RRH clustering mechanism that determines which RRHs are associated with a specific BBU pool. The second part utilizesrecurrent neural networks (RNN) to predict the daily traffic profile of RRHs, so that a relatively accurate traffic profile prediction can be obtained to facilitate the switching algorithm. Finally, the third part comprises the BBU-RRH switching scheme that works in conjunction with the predicted traffic profile to make an informed decision about the associations between RRHs and BBUs within the BBU pool. The performance of the proposed algorithm has been evaluated through simulations. The simulation results show that the proposed algorithm reduces the number of BBUs used and therefore save on energy. In addition, the algorithm reduces the occurrence of congestion and failure states, and thus improve the quality of the service of the network. Finally, the developed switching algorithm also reduces the switching complexity when compared with existing algorithms
Dynamic Response Analysis of Ash-Retention Dam and Its Earthquake-Resistant Improvement
A nonlinear stress-strain static evaluation model and an equivalent visco-elastic dynamic evaluation model, which can simulate well the static and seismic behaviors of the ash deposit, as well as the methods for analyzing the dynamic response and for improving the earthquake-resistance of the ash-retention dam are presented and illustrated through a practical engineering project in the paper
Traffic-Profile and Machine Learning Based Regional Data Center Design and Operation for 5G Network
Data center in the fifth generation (5G) network will
serve as a facilitator to move the wireless communication industry
from a proprietary hardware based approach to a more software
oriented environment. Techniques such as Software defined
networking (SDN) and network function virtualization (NFV)
would be able to deploy network functionalities such as service
and packet gateways as software. These virtual functionalities
however would require computational power from data centers.
Therefore, these data centers need to be properly placed and
carefully designed based on the volume of traffic they are meant
to serve. In this work, we first divide the city of Milan, Italy
into different zones using K-means clustering algorithm. We then
analyse the traffic profiles of these zones in the city using a
network operatorâs Open Big Data set. We identify the optimal
placement of data centers as a facility location problem and
propose the use of Weiszfeldâs algorithm to solve it. Furthermore,
based on our analysis of traffic profiles in different zones, we
heuristically determine the ideal dimension of the data center in
each zone. Additionally, to aid operation and facilitate dynamic
utilization of data center resources, we use the state of the art
recurrent neural network models to predict the future traffic
demands according to past demand profiles of each area
Research on flux of dry atmospheric falling dust and its characterization in a subtropical city, Guangzhou, South China
Guangzhou is the central city in the Pearl River Delta (PRD), China, and is one of the most polluted cities in the world. To characterize the ambient falling dust pollution, two typical sampling sites: urban (Wushan) and suburban (University Town) areas in Guangzhou city were chosen for falling dust collection over 1Â year at time intervals of 1 or 2Â months. The flux of dry deposition was calculated. In addition, mineral composition and morphology of atmospheric falling dust were studied by X-ray diffraction, scanning electron microscopy, and microscopic observation. The results revealed that the dust flux in Guangzhou city was 3.34â3.78Â g/(m2âmonth) during the study period. The main minerals in the dust were quartz, illite, calcite, kaolinite, gypsum, plagioclase, dolomite, and amorphous matter. The morphological types included grained and flaky individual minerals, chain-like aggregates, spherical flying beads, and irregular aggregates, with the chain-like and spherical aggregates indicators of industrial ash. The major dusts were derived from industrial and construction activities. The gypsum present in the dust collected in winter season was not only derived from cement dust but may also have originated from the reaction of calcic material with sulfuric acids resulting from photooxidation of SOx and NOx, which confirmed serious air pollution due to SOx and NOx in Guangzhou. The abatement of fossil fuel combustion emissions and construction dust will have a significant beneficial effect on dust reduction
Watching Stars in Pixels: The Interplay of Traffic Shaping and YouTube Streaming QoE over GEO Satellite Networks
Geosynchronous satellite (GEO) networks are a crucial option for users beyond
terrestrial connectivity. However, unlike terrestrial networks, GEO networks
exhibit high latency and deploy TCP proxies and traffic shapers. The deployment
of proxies effectively mitigates the impact of high network latency in GEO
networks, while traffic shapers help realize customer-controlled data-saver
options that optimize data usage. It is unclear how the interplay between GEO
networks' high latency, TCP proxies, and traffic-shaping policies affects the
quality of experience (QoE) for commonly used video applications. To fill this
gap, we analyze the quality of over k YouTube video sessions streamed across
a production GEO network with a Kbps shaping rate. Given the average bit
rates for the selected videos, we expected seamless streaming at p or
lower resolutions. However, our analysis reveals that this is not the case:
of TCP sessions and of gQUIC sessions experience rebuffering
events, while the median average resolution is only p for TCP and p
for gQUIC. Our analysis identifies two key factors contributing to sub-optimal
performance: (i)unlike TCP, gQUIC only utilizes of network capacity; and
(ii)YouTube's imperfect chunk request pipelining. As a result of our study, the
partner GEO ISP discontinued support for the low-bandwidth data-saving option
in U.S. business and residential markets to avoid potential degradation of
video quality -- highlighting the practical significance of our findings
Emission of PAHs, NPAHs and OPAHs from residential honeycomb coal briquette combustion
Coal
combustion is one of the most significant sources of air pollution
in China. In this study, emission factors (EFs) of 15 polycyclic aromatic
hydrocarbons (PAHs), 26 nitrated PAHs (NPAHs) and 6 oxygenated PAHs
(OPAHs) were determined in five different coals with different geological
maturity (vitrinite reflectance <i>R</i><sub>O</sub> = 0.77â1.88%)
burned in the form of honeycomb briquettes. The total EFs ranged from
9.82 to 215 mg kg<sup>â1</sup> for PAHs, 0.14 to 1.88 mg kg<sup>â1</sup> for NPAHs and 4.47 to 20.8 mg kg<sup>â1</sup> for OPAHs. Measured EFs and gas-particle partitioning varied depending
on the geological maturity. The lowest EFs were found in anthracite.
The proportion of PAHs, NPAHs and OPAHs in gaseous phase increasing
with increased geological maturity. The coal with higher geological
maturity produced more 3-ring PAHs. On the basis of the statistical
analysis for the residential sector of China in 2008, PAHs, NPAHs
and OPAHs emitted from residential honeycomb coal briquettes were
4.36 Gg, 0.03 Gg and 0.47 Gg in 2007, respectively. By 2020, the emission
would decrease to 2.18 Gg, 0.02 Gg and 0.24 Gg for PAHs, NPAHs and
OPAHs due to the increasing usage of new energy resources. If only
anthracite is used as the residential coal, 93% PAHs, 87% NPAHs and
71% OPAHs would be reduced in 2020
Full-duplex mode in amplify-and-forward relay channels: outage probability and ergodic capacity
This paper investigates the outage probability and ergodic capacity performances for full-duplex mode in two-way amplify-andforward relay channels. The two-way relay channels which consist of two source nodes and a single relay node working in full-duplex mode, are assumed as independent and identically distributed as Rayleigh fading. The self-interference or loop interference of the relay is unavoidably investigated for full-duplex mode. And the close-form expressions for the outage probability and ergodic capacity of full-duplex mode are derived, considering both loop interference and the coefficients of two-way relay amplify-andforward channels. To further facilitate the performance of full-duplex mode, the half-duplex modes over different transmission time slots are analyzed. Simulation results point out the effect of loop interference on outage probability and ergodic capacity of twoway amplify-and-forward relay channels with full-duplex mode and show that full-duplex mode can achieve better performance in terms of capacity and even outperform half-duplex modes in the presence of loop interference
- âŠ