7,090 research outputs found
Modeling of wide-band MIMO radio channels based on NLoS indoor measurements
Link to published version (if available)
A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles
In recent years, there has been a dramatic increase in the use of unmanned
aerial vehicles (UAVs), particularly for small UAVs, due to their affordable
prices, ease of availability, and ease of operability. Existing and future
applications of UAVs include remote surveillance and monitoring, relief
operations, package delivery, and communication backhaul infrastructure.
Additionally, UAVs are envisioned as an important component of 5G wireless
technology and beyond. The unique application scenarios for UAVs necessitate
accurate air-to-ground (AG) propagation channel models for designing and
evaluating UAV communication links for control/non-payload as well as payload
data transmissions. These AG propagation models have not been investigated in
detail when compared to terrestrial propagation models. In this paper, a
comprehensive survey is provided on available AG channel measurement campaigns,
large and small scale fading channel models, their limitations, and future
research directions for UAV communication scenarios
Dual-Polarized Ricean MIMO Channels: Modeling and Performance Assessment
In wireless communication systems, dual-polarized (DP) instead of
single-polarized (SP) multiple-input multiple-output (MIMO) transmission is
used to improve the spectral efficiency under certain conditions on the channel
and the signal-to-noise ratio (SNR). In order to identify these conditions, we
first propose a novel channel model for DP mobile Ricean MIMO channels for
which statistical channel parameters are readily obtained from a moment-based
channel decomposition. Second, we derive an approximation of the mutual
information (MI), which can be expressed as a function of those statistical
channel parameters. Based on this approximation, we characterize the required
SNR for a DP MIMO system to outperform an SP MIMO system in terms of the MI.
Finally, we apply our results to channel measurements at 2.53 GHz. We find
that, using the proposed channel decomposition and the approximation of the MI,
we are able to reproduce the (practically relevant) SNR values above which DP
MIMO systems outperform SP MIMO systems.Comment: submitted to the IEEE Transactions on Communication
A Study of Differences in Calculated Capacity when Using Single-, Mixed- or Multiple-Bounce GSCM Schemes
The paper looks for differences in MIMO system capacity when using either single-, mixed-, or multiple-bounce geometry based stochastic channel models (GSCMs). The investigation considers Saleh-Valenzuela temporal indoor model, expanded for angular domain. In the model omnidirectional and idealized sector antennas were used as array elements. The single-bounce assumption, combination of single and multiple bounces, and pure random multiple bounces assumption were compared within “temporally identical” environment regarding the overall MIMO capacity. Assumption of clustered scatterers/reflectors is used in all three cases. The comparison is performed in statistical sense, using a large number of stochastically generated temporal models. The model is two- dimensional, i.e. neither elevation angle nor polarization/ depolarization was considered
Spatial channel characterization for smart antenna solutions in FDD wireless networks
This paper introduces a novel metric for determining the spatial decorrelation between the up- and down-link wireless bearers in frequency division duplex (FDD) networks. This metric has direct relevance to smart or adaptive antenna array base-station deployments in cellular networks, which are known to offer capacity enhancement when compared to fixed coverage solutions. In particular, the results presented were obtained from field trial measurement campaigns for both urban and rural scenarios, with the observations having a direct impact on the choice of down-link beamforming architecture in FDD applications. Further, it is shown that significant spatial decorrelation can occur in urban deployments for bearer separations as small as 5 MHz. Results are presented in terms of both instantaneous characteristics as well as time averaged estimates, thus facilitating the appraisal of smart antenna solutions in both packet and circuit switched network
Dynamic double directional propagation channel analysis with dual circular arrays
Dynamic double directional propagation channel analysis with dual circular arrays. (pp. 6 p). Peer reviewed versio
Doctor of Philosophy
dissertationWireless communication has become an essential part of everyday life. The hunger for more data, more phone calls, more video, and more access in more places, including vehicles, is growing massively. Communication in vehicles is particularly challenging because of their extremely high multipath environment. In addition, there is significant interest in reducing the number of wires in vehicles to reduce weight, complexity, maintenance, etc. and replace them with wireless systems. Preliminary research shows that MIMO systems take advantage of the extreme multipath environment found in aircraft and other vehicles and also provides more consistent channel capacity than SISO systems. The purpose of this research was to quantify complex channels (including the aircraft/vehicle environment) and their relation to other environments, evaluate MIMO in aircraft, provide design constraints for accurately modeling complex channels, and provide information to predict optimum antenna type and location to enable communication in aircraft/cars/buses/ships/trains/etc. and other extreme channels. The ability to evaluate and design MIMO technologies from the guidelines in this paper is potentially transformative for aircraft safety - enabling a new generation of location specific monitoring and maintenance. Average measured capacity was found to be between 18 and 21 bits/s/Hz using a 4x4 array of antennas, and had no direct relation to the size of the channel. Site-specific capacity showed a multipath rich channel, varying between 15 to 23 bits/s/Hz. The capacity decreased for increasing measurement distance, with exceptions near reflective objects that increase multipath. Due to these special circumstances for site-specific locations within complex channels, it is recommended that 3D ray tracing be used for modeling as it is more accurate than commonly used statistical models, within 1.1 bits/s/Hz. This showed that our 3D ray tracing is adaptable to various environments and gives a more accurate depiction than statistical models that average channel variations. This comes at the cost of greater model complexity. If increased complexity is not desirable, Nakagami 1.4 could be used as the next most accurate model. Design requirements for modeling different complex channels involve a detailed depiction of channel geometry, including height, width, length, shape (square, cylindrical, slanted walls, etc.), large windows, and reflective objects inside the channel space, especially those near the transmitter. Overall, the multipath rich channel found in vehicles is an excellent environment for MIMO systems. These complex channels can be simulated accurately without measurement and before they are even built using our sitespecific 3D ray tracing software combined with a detailed signal model to incorporate antenna effects
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