scholarly journals Channel Propagation Characteristics on the Performance of 4G Cellular Systems from High Altitude Platforms (HAPs)

2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Kabiru Yusuf ◽  
Dahiru Sani Shuaibu ◽  
Suleiman Aliyu Babale
Keyword(s):  
High Altitude ◽  
Channel Model ◽  
Elevation Angle ◽  
Base Station ◽  
Cellular Systems ◽  
Frequency Variation ◽  
Propagation Characteristics ◽  
Technical Limitation ◽  
Proposed Model ◽  
High Altitude Platforms

In this paper, we investigated the effect of different channel propagation characteristics on the performance of 4G systems from high altitude platforms (HAPs). The use of High-Altitude Platforms for communication purpose in the past focused mostly on the assumption that the platform is quasi stationary. The technical limitation of the assumption was that of ensuring stability in the positioning of the platform in space. The use of antenna steering and other approaches were proposed as a solution to the said problem. In this paper, we proposed a channel model which account for the motion of the platform. This was done by investigating the effect of Doppler shift on the carrier frequency as the signals propagate between the transmitter and receiver while the High-Altitude Platform is in motion. The basic free space model was used and subjected to the frequency variation caused by the continuous random shift due to the motion of the HAPs. The trajectory path greatly affects the system performance. A trajectory of 30km, 100km and 500km radii were simulated. An acute elevation angle was used in the simulation. The proposed model was also compared to two other channel models to illustrate its performance. The results show that the proposed model behave similar to the existing models except at base station ID 35 and 45 where the highest deviation of 20dBm was observed. Other stations that deviated were less than 2dBm.

scholarly journals The Impact of Antenna Height on 3D-MIMO Channel: a Ray Launching Based Analysis

2017 ◽  
Author(s):  
Qi Hong ◽  
Jiliang Zhang ◽  
Hui Zheng ◽  
Hao Li ◽  
Haonan Hu ◽  
...  
Keyword(s):  
Channel Model ◽  
Elevation Angle ◽  
Base Station ◽  
Mimo Channel ◽  
Delay Spread ◽  
Three Dimension ◽  
Angle Of Arrival ◽  
3D Mimo ◽  
The Impact ◽  
Ray Launching

Three dimension (3D) Multi-input-multi-output (MIMO) scheme, which exploits another dimension of the spatial resource, is one of the enabling technologies for the next generation mobile communication. As the elevation angle in 3D-MIMO channel model might varies against the height of the base station transmit antenna, it has to be taken into account carefully. In this paper, the impact of antenna height on the channel characteristics of 3D MIMO channel is investigated by using the intelligent ray launching algorithm (IRLA). Three typical street scenarios, i.e., the straight street, the fork road and the cross road, are selected as benchmarks. On the basis of simulations, joint and marginal probability density functions (PDFs) of both the elevation angle of departure (EAoD) and the elevation angle of arrival (EAoA) are obtained. The elevation angle spread (AS) and the delay spread (DS) under various antenna heights are also discussed. Simulation results indicate that the PDFs of EAoD and EAoA vary characteristics under different street scenarios. Moreover, the minimum value of the DS can be achieved when the antenna height is half of the building height.

Capacity Limits of Base Station Cooperation in Cellular Networks

2010 ◽  
pp. 102-132
Author(s):  
Symeon Chatzinotas ◽  
Muhammad Ali Imran ◽  
Reza Hoshyar
Keyword(s):  
Channel Model ◽  
High Capacity ◽  
Path Loss ◽  
Base Station ◽  
Cellular Systems ◽  
Current Channel ◽  
Capacity Limits ◽  
Base Station Cooperation ◽  
Rate Capacity ◽  
Sum Rate

In the information-theoretic literature, it has been widely shown that multicell processing is able to provide high capacity gains in the context of cellular systems. What is more, it has been proved that the per-cell sum-rate capacity of multicell processing systems grows linearly with the number of base station (BS) receive antennas. However, the majority of results in this area have been produced assuming that the fading coefficients of the MIMO subchannels are completely uncorrelated. In this direction, this chapter investigates the ergodic per-cell sum-rate capacity of the Gaussian MIMO cellular channel under correlated fading and BS cooperation (multicell processing). More specifically, the current channel model considers Rayleigh fading, uniformly distributed user terminals (UTs) over a planar cellular system, and power-law path loss. Furthermore, both BSs and UTs are equipped with correlated multiple antennas, which are modelled according to the Kronecker product correlation model. The per-cell sum-rate capacity is evaluated while varying the cell density of the system, as well as the level of receive and transmit correlation. In this context, it is shown that the capacity performance is compromised by correlation at the BS-side, whereas correlation at the UT-side has a negligible effect on the system’s capacity.

scholarly journals A Semi-Stochastic Propagation Model for the Study of Beam Tilting in Cellular Systems

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Konstantinos B. Baltzis
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Signal To Noise Ratio ◽  
Base Station ◽  
Cellular Systems ◽  
Propagation Model ◽  
Beam Tilting ◽  
Tilting Angle ◽  
Proposed Model ◽  
The Impact

Base station antenna downtilt mitigates interference and improves the downlink performance of wireless systems. A semi-stochastic propagation model is presented and applied to the study of the impact of the base station beam tilting in cellular communications. The two-ray approximation of the proposed model is described analytically. Beam tilting is evaluated in relation to the base station antenna radiation pattern, the antennas height, the propagation environment, the bit error rate, and the signal-to-noise ratio at the receiver front end. Analytically derived expressions for the fading envelopes, the error probability, the optimum tilting angle, and the downlink capacity of a WCDMA system are derived. Theoretical analysis and simulation results are provided to show the characteristics of the model. Comparisons with data in the literature confirm its validity. Furthermore, the effect of beam tilting on system downlink performance in terms of bit error rate and capacity is investigated.

A Review on 3GPP 5G Security Aspects

2019 ◽  
Author(s):  
Rajavelsamy R ◽  
Debabrata Das
Keyword(s):  
Network Architecture ◽  
Base Station ◽  
Cellular Systems ◽  
Core Network ◽  
User Privacy ◽  
Wireless Backhaul ◽  
Level Of Use ◽  
Unified Authentication ◽  
3Rd Generation Partnership Project ◽  
5G Security

5G promises to support new level of use cases that will deliver a better user experience. The 3rd Generation Partnership Project (3GPP) [1] defined 5G system introduced fundamental changes on top of its former cellular systems in several design areas, including security. Unlike in the legacy systems, the 5G architecture design considers Home control enhancements for roaming customer, tight collaboration with the 3rd Party Application servers, Unified Authentication framework to accommodate various category of devices and services, enhanced user privacy, and secured the new service based core network architecture. Further, 3GPP is investigating the enhancements to the 5G security aspects to support longer security key lengths, False Base station detection and wireless backhaul in the Phase-2 of 5G standardization [2]. This paper provides the key enhancements specified by the 3GPP for 5G system, particularly the differences to the 4G system and the rationale behind the decisions.

Broadband from heaven [high altitude platforms]

2004 ◽  
Vol 2 (2) ◽  
pp. 18-23 ◽  
Author(s):  
S. Karapantazis ◽  
F.N. Pavlidou
Keyword(s):  
High Altitude ◽  
High Altitude Platforms

scholarly journals Comparison of solar power measurements in alpine areas using a mobile dual-axis tracking system

2019 ◽  
Vol 2 (S1) ◽  
Author(s):  
Jelenko Karpić ◽  
Ekanki Sharma ◽  
Tamer Khatib ◽  
Wilfried Elmenreich
Keyword(s):  
High Altitude ◽  
Peak Power ◽  
Power Plants ◽  
Low Cost ◽  
Elevation Angle ◽  
Test Site ◽  
Maximum Power ◽  
Maximum Power Point ◽  
Photovoltaic Power ◽  
Power Point

Abstract The rising demand for sustainable energy requires to identify the sites for photovoltaic systems with the best performance. This paper tackles the question of feasibility of photovoltaic power plants at high altitude. A direct comparison between an alpine and an urban area site is conducted in the south of Austria. Two low-cost automatic photovoltaic power measurement devices with dual-axis sun tracking and maximum power point tracking are deployed at two test sites. The system periodically performs a scan over the southern semihemisphere and executes maximum power point adjustment in order to assess the performance for a given direction. The gathered data shows a higher photovoltaic power yield in the higher altitude test site. Furthermore, the high altitude photovoltaic power as a function of azimuth and elevation angle appears to be not only higher but also more flat than in lower altitudes. This indicates a lower power loss in case of deviation from the optimal solar angles. The results show that even on low-cost hardware a difference in photovoltaic power can be observed, even though in this experiment it amounts to less than 5% increase of peak power in higher altitudes. However, the measured peak powers on the mountain are more stable and therefore closer to a constant level than the heavily fluctuating peak power values at the low altitude site. Additionally, a slight shift in optimal elevation angles between altitudes can be observed, as the optimum angle turns out to be lower on the high altitude site. This angle shift could be caused by snow reflections on the mountainous test site.

Sign in / Sign up

Export Citation Format

Share Document