scholarly journals Radio Channel Scattering in a 28 GHz Small Cell at a Bus Stop: Characterization and Modelling

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1556
Author(s):  
Manuel García Sánchez ◽  
Alejandro Santomé Valverde ◽  
Isabel Expósito
Keyword(s):  
Radio Channel ◽  
Small Cell ◽  
Doppler Spectrum ◽  
Delay Spread ◽  
Bus Stop ◽  
Fifth Generation ◽  
Sweep Time ◽  
The Impact ◽  
Cell Networks ◽  
Do So

The 28 GHz band is one of the available bands in Frequency Range 2 (FR2), above 6 GHz, for fifth generation (5G) communications. The propagation characteristics at this frequency band, together with the bandwidth requirements of 5G communications, make it suitable for ultra-dense smart cell networks. In this paper, we investigate the performance of a radio channel in the presence of moving, scattering sources for a small cell at 28 GHz, located at a bus stop. To do so, measurements of the channel complex impulse response with a sweep time delay cross-correlation sounder were made and then used to examine the distribution of multipath components. Besides analyzing the delay spread caused by the channel, we also evaluate the impact on the Doppler spectrum (DS) caused by the vehicles passing near the bus stop. We show that delay components are grouped in clusters exhibiting exponential decay power. We also show that the DS varies with time as vehicles pass by, so the channel cannot be considered stationary. We propose an empirical DS model, where the model parameter should change with time to describe the non-stationary nature of the radio channel. We have also found that the DS with maximum spread is similar for channel contributions in different delay clusters.

scholarly journals Vehicle-to-Vehicle Radio Channel Characteristics for Congestion Scenario in Dense Urban Region at 5.9 GHz

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Yishui Shui ◽  
Fang Li ◽  
Junyi Yu ◽  
Wei Chen ◽  
Changzhen Li ◽  
...  
Keyword(s):  
Communication Systems ◽  
Radio Channel ◽  
Average Power ◽  
Urban Region ◽  
Doppler Spectrum ◽  
Small Scale ◽  
Power Delay Profile ◽  
Car Following ◽  
Vehicle To Vehicle ◽  
The Impact

This paper reports the results of a car-following measurement of the wireless propagation channel at 5.9 GHz on a seriously congested urban road in Wuhan, China. The small-scale amplitude-fading distribution was determined to be a Ricean distribution using the Akaike information criterion. This result shows that this car-following scenario can be regarded as a line-of-sight radio channel. Moreover, the statistical K-factor features follow a Gaussian distribution. According to the power delay profile and average power delay profile, we found that street buildings in this dense urban environment contributed to very strong reflection phenomena. The impact of a powerful reflection is analyzed through path loss, delay, and Doppler spreads in the channel statistical properties. In the frequency domain, we observe a U-shape delay-Doppler spectrum that proved that the dense urban scenario consists of scattering channels. All these results are summarized in tabular form that will be useful in the modeling of vehicle-to-vehicle wireless communication systems.

The impact of breakdowns disciplines and repeated attempts on performances of Small Cell Networks

2014 ◽  
Vol 5 (4) ◽  
pp. 633-644 ◽  
Author(s):  
Nawel Gharbi ◽  
Besma Nemmouchi ◽  
Lynda Mokdad ◽  
Jalel Ben-Othman
Keyword(s):  
Small Cell ◽  
Small Cell Networks ◽  
The Impact ◽  
Cell Networks

Do we Need Maintenance Chemotherapy in Advanced NSCLC in the Era of Immune and Targeted Therapy?

2019 ◽  
Vol 15 (1) ◽  
pp. 50-55
Author(s):  
Ahmed Nagy ◽  
Omar Abdel Rahman ◽  
Heba Abdullah ◽  
Ahmed Negida
Keyword(s):  
Lung Cancer ◽  
Maintenance Therapy ◽  
Small Cell Lung Cancer ◽  
Cell Lung Cancer ◽  
Statistical Significance ◽  
Small Cell ◽  
Maintenance Chemotherapy ◽  
Small Cell Lung ◽  
The Impact

Background: Although well established for the effective management of hematologic cancers, maintenance chemotherapy has only been recently incorportated as a treatment paradigm for advanced non–small-cell lung cancer. Maintenance chemotherapy aims to prolong a clinically favorable response state achieved after finishing induction therapy which is usually predefined in number before startng treatment. There are 2 modalities for maintenance therapy; continuation maintenance (involving a non-platinum component which was a part of the induction protocol or a targeted agent) and switch maintenance therapy (utilizing a new agent which was not a part of the induction regimen). Methods: The purpose of this article is to review the role of maintenance therapy in the treatment of advanced Non-Small Cell Lung Cancer (NSCLC) and provide a brief overview about induction chemotherapy in NSCLC to address the basis of maintenance therapy as a treatment option. We will also compare the impact of maintenance chemotherapy with the now evolving role of immunotherapy in NSCLC. Results: There have been 4 maintenance studies to date showing prolonged PFS and OS with statistical significance. However, Three out of the four studies (ECOG4599, JMEN, and PARAMOUNT) did not report tumor molecular analysis. As regard Immunotherapy, current data is in favour of strongly an increasing role for immunotherapy in NSCLC. Conclusion: Maintenance therapy in NSCLC continues to be an important therapeutic line to improve outcome in patients with metastatic and recurrent disease.

Reconstituting the International, 1918–1923

2017 ◽  
Author(s):  
Talbot C. Imlay
Keyword(s):  
Seismic Events ◽  
Great War ◽  
Bolshevik Revolution ◽  
Meaning And Purpose ◽  
Post War ◽  
The Impact ◽  
First Time ◽  
The Great War ◽  
Do So ◽  
Lengthy Process

This chapter examines the post-war efforts of European socialists to reconstitute the Socialist International. Initial efforts to cooperate culminated in an international socialist conference in Berne in February 1919 at which socialists from the two wartime camps met for the first time. In the end, however, it would take four years to reconstitute the International with the creation of the Labour and Socialist International (LSI) in 1923. That it took so long to do so is a testimony to the impact of the Great War and to the Bolshevik revolution. Together, these two seismic events compelled socialists to reconsider the meaning and purpose of socialism. The search for answers sparked prolonged debates between and within the major parties, profoundly reconfiguring the pre-war world of European socialism. One prominent stake in this lengthy process, moreover, was the nature of socialist internationalism—both its content and its functioning.

scholarly journals Performance Analysis and Design Considerations of the Shallow Underwater Optical Wireless Communication System with Solar Noises Utilizing a Photon Tracing-Based Simulation Platform

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 632
Author(s):  
Xiaozheng Wang ◽  
Minglun Zhang ◽  
Hongyu Zhou ◽  
Xiaomin Ren
Keyword(s):  
Performance Analysis ◽  
Wireless Communication ◽  
Ambient Noise ◽  
Large Scale ◽  
Delay Spread ◽  
Simulation Platform ◽  
Optical Wireless Communication ◽  
Optical Wireless ◽  
Analysis And Design ◽  
The Impact

The performance of the underwater optical wireless communication (UOWC) system is highly affected by seawater´s inherent optical properties and the solar radiation from sunlight, especially for a shallow environment. The multipath effect and degradations in signal-to-noise ratio (SNR) due to absorption, scattering, and ambient noises can significantly limit the viable communication range, which poses key challenges to its large-scale commercial applications. To this end, this paper proposes a unified model for underwater channel characterization and system performance analysis in the presence of solar noises utilizing a photon tracing algorithm. Besides, we developed a generic simulation platform with configurable parameters and self-defined scenarios via MATLAB. Based on this platform, a comprehensive investigation of underwater channel impairments was conducted including temporal and spatial dispersion, illumination distribution pattern, and statistical attenuation with various oceanic types. The impact of ambient noise at different operation depths on the bit error rate (BER) performance of the shallow UOWC system was evaluated under typical specifications. Simulation results revealed that the multipath dispersion is tied closely to the multiple scattering phenomenon. The delay spread and ambient noise effect can be mitigated by considering a narrow field of view (FOV) and it also enables the system to exhibit optimal performance on combining with a wide aperture.

scholarly journals Analysis of Non-Stationarity for 5.9 GHz Channel in Multiple Vehicle-to-Vehicle Scenarios

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3626
Author(s):  
Fang Li ◽  
Wei Chen ◽  
Yishui Shui
Keyword(s):  
Transmission Rate ◽  
Radio Channel ◽  
Vertical Direction ◽  
Statistical Characteristics ◽  
Small Scale ◽  
Delay Spread ◽  
Important Indicator ◽  
Power Delay Profile ◽  
Channel Characteristics ◽  
Vehicle To Vehicle

The vehicle-to-vehicle (V2V) radio channel is non-stationary due to the rapid movement of vehicles. However, the stationarity of the V2V channels is an important indicator of the V2V channel characteristics. Therefore, we analyzed the non-stationarity of V2V radio channels using the local region of stationarity (LRS). We selected seven scenarios, including three directions of travel, i.e., in the same, vertical, and opposite directions, and different speeds and environments in a similar driving direction. The power delay profile (PDP) and LRS were estimated from the measured channel impulse responses. The results show that the most important influences on the stationary times are the direction and the speed of the vehicles. The average stationary times for driving in the same direction range from 0.3207 to 1.9419 s, the average stationary times for driving in the vertical direction are 0.0359–0.1348 s, and those for driving in the opposite direction are 0.0041–0.0103 s. These results are meaningful for the analysis of the statistical characteristics of the V2V channel, such as the delay spread and Doppler spread. Small-scale fading based on the stationary times affects the quality of signals transmitted in the V2V channel, including the information transmission rate and the information error code rate.

scholarly journals On the Performance of UAV-Aided Content Caching in Small-Cell Networks with Joint Transmission

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1040
Author(s):  
Menghan Wei ◽  
Youjia Chen ◽  
Ming Ding
Keyword(s):  
Transmission Rate ◽  
High Mobility ◽  
Limited Resource ◽  
Small Cell ◽  
Base Stations ◽  
Cell Content ◽  
Small Cell Networks ◽  
Content Caching ◽  
Cell Networks ◽  
Joint Transmission

Unmanned aerial vehicles (UAVs), featured by the high-mobility and high-quality propagation environment, have shown great potential in wireless communication applications. In this paper, a novel UAV-aided small-cell content caching network is proposed and analyzed, where joint transmission (JT) is considered in the dense small-cell networks and mobile UAVs are employed to shorten the serving distance. The system performance is evaluated in terms of the average cache hit probability and the ergodic transmission rate. From the analytical results, we find that (i) the proposed UAV-aided small-cell network shows superior caching performance and, even with a small density of UAVs the system’s cache hit probability, can be improved significantly; (ii) the content’s optimal caching probability to maximize the cache hit probability is proportional to the (K+1)-th root of its request probability, where K is the number of small-cell base stations that serve each user by JT; (iii) caching the most popular content in UAVs may lead to a low transmission rate due to the limited resource offered by the low-density UAVs. Simulation results are presented to validate the theoretical results and the performance gain achieved by the optimal caching strategy.

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