519 research outputs found
Exploiting mm-wave communications to boost the performance of industrial wireless networks
This work explores the potentiality of millimeter waves (mmW) as physical layer in industrial wireless networks. Innovative models and a link design method are proposed to achieve reliable communication, at a distance of tens of meters for a single hop, even in harsh environments. By exploiting the worldwide-free band of several GHz, available around 60 GHz, mmW links allow to achieve a performance boosting of up to two orders of magnitude, w.r.t. conventional sub-6-GHz wireless links, in indoor industrial environments. Time slotted channel hopping and frequency-diversity can be implemented with a large number of channels, and with high bit rate (several Mb/s per channel). This allows for robust networking of high data-rate sensors, such as cameras, radars, or laser scanners. Featuring a low bit error rate, mmW communication allows for low-latency link and large number of hops in networks with a large radius. Finally, it ensures interference separation from operating frequencies of electrical machines, switching converters, and other industrial wireless networks (e.g., 802.11 or 802.15). Implementation results for key HWblocks in low-cost technologies show the feasibility of mmW communication nodes with low-power and compact size
Compendium of Applications Technology Satellite user experiments
The achievements of the user experiments performed with ATS satellites from 1967 to 1973 are summarized. Included are fixed and mobile point to point communications experiments involving voice, teletype and facsimile transmissions. Particular emphasis is given to the Alaska and Hawaii satellite communications experiments. The use of the ATS satellites for ranging and position fixing of ships and aircraft is also covered. The structure and operating characteristics of the various ATS satellite are briefly described
Impact of Line-of-Sight and Unequal Spatial Correlation on Uplink MU-MIMO Systems
Closed-form approximations of the expected per-terminal
signal-to-interference-plus-noise-ratio (SINR) and ergodic sum spectral
efficiency of a multiuser multiple-input multiple-output system are presented.
Our analysis assumes spatially correlated Ricean fading channels with
maximum-ratio combining on the uplink. Unlike previous studies, our model
accounts for the presence of unequal correlation matrices, unequal Rice
factors, as well as unequal link gains to each terminal. The derived
approximations lend themselves to useful insights, special cases and
demonstrate the aggregate impact of line-of-sight (LoS) and unequal correlation
matrices. Numerical results show that while unequal correlation matrices
enhance the expected SINR and ergodic sum spectral efficiency, the presence of
strong LoS has an opposite effect. Our approximations are general and remain
insensitive to changes in the system dimensions, signal-to-noise-ratios, LoS
levels and unequal correlation levels.Comment: 4 pages, 2 figures, accepted for publication in the IEEE Wireless
Communications Letters, Vol. 6, 201
Capacity and Error Rate Analysis of MIMO Satellite Communication Systems in Fading Scenarios
In this paper, we investigated the capacity and bit error rate (BER) performance of Multiple Input Multiple Output (MIMO) satellite systems with single and multiple dual polarized satellites in geostationary orbit and a mobile ground receiving station with multiple antennas. We evaluated the effects of both system parameters such as number of satellites, number of receive antennas, and SNR and environmental factors including atmospheric signal attenuations and signal phase disturbances on the overall system performance using both analytical and spatial models for MIMO satellite systems.DOI:http://dx.doi.org/10.11591/ijece.v4i4.534
Uplink Multiuser MIMO Detection Scheme with Reduced Computational Complexity
The wireless communication systems with multiple antennas have recently received significant attention due to their higher capacity and better immunity to fading channels as compared to single antenna systems. A fast antenna selection scheme has been introduced for the uplink multiuser multiple-input multiple-output (MIMO) detection to achieve diversity gains, but the computational complexity of the fast antenna selection scheme in multiuser systems is very high due to repetitive pseudo-inversion computations. In this paper, a new uplink multiuser detection scheme is proposed adopting a switch-and-examine combining (SEC) scheme and the Cholesky decomposition to solve the computational complexity problem. K users are considered that each users is equipped with two transmit antennas for Alamouti space-time block code (STBC) over wireless Rayleigh fading channels. Simulation results show that the computational complexity of the proposed scheme is much lower than the systems with exhaustive and fast antenna selection, while the proposed scheme does not experience the degradations of bit error rate (BER) performances
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