Spatial Diversity Gain of Micrometer-scale MIMO FSO Transceivers utilizing Multicore Fiber and 2-D Photodetector Array

2018 ◽  
Author(s):  
Yuki Yoshida ◽  
Toshimasa Umezawa ◽  
Naokatsu Yamamoto
Keyword(s):  
Spatial Diversity ◽  
Diversity Gain ◽  
Photodetector Array ◽  
Micrometer Scale ◽  
Multicore Fiber

scholarly journals Optical Filter-Less WDM for Visible Light Communications Using Defocused MIMO

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1065
Author(s):  
Andrew Burton ◽  
Petr Chvojka ◽  
Paul Anthony Haigh ◽  
Zabih Ghassemlooy ◽  
Stanislav Zvanovec
Keyword(s):  
Visible Light ◽  
Wavelength Division Multiplexing ◽  
Light Emitting Diode ◽  
Multiple Input Multiple Output ◽  
Optical Filter ◽  
Spatial Diversity ◽  
Visible Light Communications ◽  
Light Emitting ◽  
Photodetector Array ◽  
The Individual

This paper experimentally investigates, for the first time, a new wavelength-division multiplexing-based visible light communications link based on a defocused non-imaging multiple-input multiple-output (MIMO), which removes the need for tuned optical bandpass filters paired with each receiver. The proposed system is based on using the natural diversity of the individual light emitting diodes (LEDs) within a single light source to generate an H-matrix, which is independent of spatial diversity. We show that, by transmitting K-independent sets of non-return to zero on-and-off keying signals on separate wavelengths, the received superposed symbols can be demultiplexed. The non-imaging MIMO diversity is achieved by considering the power-current characteristics of the light emitting diode, the responsivity of the photodetector array, and the defocused beam spot. The system is empirically verified for K = 3 using red, green, and blue LEDs with Q-factors of 7.66, 7.69, and 4.75 dB, respectively.

scholarly journals Interference Range-Reduced Cooperative Multiple Access with Optimal Relay Selection for Large Scale Wireless Networks

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2565 ◽  
Author(s):  
Kai Liu ◽  
Rui Wang ◽  
Caizhao Yue ◽  
Feng Liu ◽  
Tao Lu ◽  
...  
Keyword(s):  
Wireless Networks ◽  
Spatial Frequency ◽  
Relay Selection ◽  
Large Scale ◽  
Spatial Diversity ◽  
Frequency Reuse ◽  
Network Throughput ◽  
Diversity Gain ◽  
Interference Range ◽  
Simulation Results

Cooperative communication improves the link throughput of wireless networks through spatial diversity. However, it reduces the frequency reuse of the entire network due to the enlarged link interference range introduced by each helper. In this paper, we propose a cooperative medium access control (MAC) protocol with optimal relay selection (ORS-CMAC) for multihop, multirate large scale networks, which can reduce the interference range and improve the network throughput. Then, we investigate the performance gain achieved by these two competitive factors, i.e., the spatial frequency reuse gain and spatial diversity gain, in large scale wireless networks. The expressions of maximum network throughput for direct transmissions and cooperative transmissions in the whole network are derived as a function of the number of concurrent transmission links, data packet length, and average packet transmission time. Simulation results validate the effectiveness of the theoretical results. The theoretical and simulation results show that the helper can reduce the spatial frequency reuse slightly, and spatial diversity gain can compensate for the decrease of the spatial frequency reuse, thereby improving the network throughput from the viewpoint of the whole network.

scholarly journals Diversity Gain Influenced by Polarization and Spatial Diversity Techniques in Ultrawideband

IEEE Access ◽  
2015 ◽  
Vol 3 ◽  
pp. 281-286 ◽  
Author(s):  
Mohsen Koohestani ◽  
Ahmed Hussain ◽  
Antonio A. Moreira ◽  
Anja K. Skrivervik
Keyword(s):  
Spatial Diversity ◽  
Diversity Gain ◽  
Diversity Techniques

scholarly journals Optimum Signal Shaping for MIMO Radar System

2017 ◽  
Vol 11 (11) ◽  
pp. 1
Author(s):  
Jamal S. Rahhal
Keyword(s):  
Phased Array ◽  
Spatial Diversity ◽  
Mimo Radar ◽  
Radar System ◽  
Diversity Gain ◽  
Good Utilization ◽  
Phased Array Radar ◽  
Signal Diversity

signal and hence, spatial diversity gain is obtained. A MIMO radar system, transmit via its diverse antennas multiple probing signals that is used to detect targets. The receiving antennas combined together form independent units. Their signals can be processed to make use from the diversity gain and better identifies the targets. In this paper, optimal probing signals are derived and its performance is simulated. MIMO radar can transmit different orthogonal signals that lead to signal diversity. Results showed good utilization of spatial diversity and better timing detection when using the optimal signals over the conventional phased array radar.

MIMO Systems in a Composite Fading and Generalized Noise Scenario: A Review

2020 ◽  
Vol 14 ◽  
Author(s):  
Keerti Tiwari
Keyword(s):  
System Performance ◽  
Performance Enhancement ◽  
Channel Model ◽  
Mimo Systems ◽  
Mimo System ◽  
Spatial Diversity ◽  
Spatial Multiplexing ◽  
Channel Models ◽  
Efficient System ◽  
Composite Channel

: Multiple-input multiple-output (MIMO) systems have been endorsed to enable future wireless communication requirements. The efficient system designing appeals an appropriate channel model, that considers all the dominating effects of wireless environment. Therefore, some complex or less analytically acquiescent composite channel models have been proposed typically for single-input single-output (SISO) systems. These models are explicitly employed for mobile applications, though, we need a specific study of a model for MIMO system which can deal with radar clutters and different indoor/outdoor and mobile communication environments. Subsequently, the performance enhancement of MIMO system is also required in such scenario. The system performance enhancement can be examined by low error rate and high capacity using spatial diversity and spatial multiplexing respectively. Furthermore, for a more feasible and practical system modeling, we require a generalized noise model along with a composite channel model. Thus, all the patents related to MIMO channel models are revised to achieve the near optimal system performance in real world scenario. This review paper offers the methods to improve MIMO system performance in less and severe fading as well as shadowing environment and focused on a composite Weibull-gamma fading model. The development is the collective effects of selecting the appropriate channel models, spatial multiplexing/detection and spatial diversity techniques both at the transmitter and the receivers in the presence of arbitrary noise.

scholarly journals Drivers of Macrophyte and Diatom Diversity in a Shallow Hypertrophic Lake

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1569
Author(s):  
Kateřina Šumberová ◽  
Ondřej Vild ◽  
Michal Ducháček ◽  
Martina Fabšičová ◽  
Jan Potužák ◽  
...  
Keyword(s):  
Fish Farming ◽  
Spatial Diversity ◽  
Spatiotemporal Variability ◽  
Water Level Fluctuations ◽  
Nutrient Requirements ◽  
Diatom Assemblages ◽  
Climatic Extremes ◽  
Growing Seasons ◽  
High Species Richness ◽  
Different Parts

We studied macrophyte and diatom assemblages and a range of environmental factors in the large hypertrophic Dehtář fishpond (Southern Bohemia, Czech Republic) over the course of several growing seasons. The spatial diversity of the environment was considered when collecting diatoms and water samples in three distinct parts of the fishpond, where automatic sensor stations continually measuring basic factors were established. Macrophytes were mapped in 30 segments of the fishpond littoral altogether. High species richness and spatiotemporal variability were found in assemblages of these groups of autotrophs. Water level fluctuations, caused by the interaction of fish farming management and climatic extremes, were identified as one of the most important factors shaping the structure and species composition of diatom and macrophyte assemblages. The distance of the sampling sites from large inflows reflected well the spatial variability within the fishpond, with important differences in duration of bottom drainage and exposure to disturbances in different parts of the fishpond. Disturbances caused by intensive wave action are most probably a crucial factor allowing the coexistence of species with different nutrient requirements under the hypertrophic conditions of the Dehtář fishpond. Due to a range of variables tested and climatic extremes encountered, our study may be considered as a basis for predictive model constructions in similar hypertrophic water bodies under a progressing climate change.

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