70,031 research outputs found
ns-3 Implementation of the 3GPP MIMO Channel Model for Frequency Spectrum above 6 GHz
Communications at mmWave frequencies will be a key enabler of the next
generation of cellular networks, due to the multi-Gbps rate that can be
achieved. However, there are still several problems that must be solved before
this technology can be widely adopted, primarily associated with the interplay
between the variability of mmWave links and the complexity of mobile networks.
An end-to-end network simulator represents a great tool to assess the
performance of any proposed solution to meet the stringent 5G requirements.
Given the criticality of channel propagation characteristics at higher
frequencies, we present our implementation of the 3GPP channel model for the
6-100 GHz band for the ns-3 end-to-end 5G mmWave module, and detail its
associated MIMO beamforming architecture
End-to-End Simulation of 5G mmWave Networks
Due to its potential for multi-gigabit and low latency wireless links,
millimeter wave (mmWave) technology is expected to play a central role in 5th
generation cellular systems. While there has been considerable progress in
understanding the mmWave physical layer, innovations will be required at all
layers of the protocol stack, in both the access and the core network.
Discrete-event network simulation is essential for end-to-end, cross-layer
research and development. This paper provides a tutorial on a recently
developed full-stack mmWave module integrated into the widely used open-source
ns--3 simulator. The module includes a number of detailed statistical channel
models as well as the ability to incorporate real measurements or ray-tracing
data. The Physical (PHY) and Medium Access Control (MAC) layers are modular and
highly customizable, making it easy to integrate algorithms or compare
Orthogonal Frequency Division Multiplexing (OFDM) numerologies, for example.
The module is interfaced with the core network of the ns--3 Long Term Evolution
(LTE) module for full-stack simulations of end-to-end connectivity, and
advanced architectural features, such as dual-connectivity, are also available.
To facilitate the understanding of the module, and verify its correct
functioning, we provide several examples that show the performance of the
custom mmWave stack as well as custom congestion control algorithms designed
specifically for efficient utilization of the mmWave channel.Comment: 25 pages, 16 figures, submitted to IEEE Communications Surveys and
Tutorials (revised Jan. 2018
High order fluid model for streamer discharges. II. Numerical solution and investigation of planar fronts
The high order fluid model developed in the preceding paper is employed here
to study the propagation of negative planar streamer fronts in pure nitrogen.
The model consists of the balance equations for electron density, average
electron velocity, average electron energy and average electron energy flux.
These balance equations have been obtained as velocity moments of Boltzmann's
equation and are here coupled to the Poisson equation for the space charge
electric field. Here the results of simulations with the high order model, with
a PIC/MC (Particle in cell/Monte Carlo) model and with the first order fluid
model based on the hydrodynamic drift-diffusion approximation are presented and
compared. The comparison with the MC model clearly validates our high order
fluid model, thus supporting its correct theoretical derivation and numerical
implementation. The results of the first order fluid model with local field
approximation, as usually used for streamer discharges, show considerable
deviations. Furthermore, we study the inaccuracies of simulation results caused
by an inconsistent implementation of transport data into our high order fluid
model. We also demonstrate the importance of the energy flux term in the high
order model by comparing with results where this term is neglected. Finally,
results with an approximation for the high order tensor in the energy flux
equation is found to agree well with the PIC/MC results for reduced electric
fields up to 1000 Townsend, as considered in this work.Comment: 26 pages, 11 figure
Radio interferometric imaging of spatial structure that varies with time and frequency
The spatial-frequency coverage of a radio interferometer is increased by
combining samples acquired at different times and observing frequencies.
However, astrophysical sources often contain complicated spatial structure that
varies within the time-range of an observation, or the bandwidth of the
receiver being used, or both. Image reconstruction algorithms can been designed
to model time and frequency variability in addition to the average intensity
distribution, and provide an improvement over traditional methods that ignore
all variability. This paper describes an algorithm designed for such
structures, and evaluates it in the context of reconstructing three-dimensional
time-varying structures in the solar corona from radio interferometric
measurements between 5 GHz and 15 GHz using existing telescopes such as the
EVLA and at angular resolutions better than that allowed by traditional
multi-frequency analysis algorithms.Comment: 12 pages, 4 figures. SPIE Proceedings, Optical
Engineering+Applications; Image Reconstruction from Incomplete Dat
Integration of Carrier Aggregation and Dual Connectivity for the ns-3 mmWave Module
Thanks to the wide availability of bandwidth, the millimeter wave (mmWave)
frequencies will provide very high data rates to mobile users in next
generation 5G cellular networks. However, mmWave links suffer from high
isotropic pathloss and blockage from common materials, and are subject to an
intermittent channel quality. Therefore, protocols and solutions at different
layers in the cellular network and the TCP/IP protocol stack have been proposed
and studied. A valuable tool for the end-to-end performance analysis of mmWave
cellular networks is the ns-3 mmWave module, which already models in detail the
channel, Physical (PHY) and Medium Access Control (MAC) layers, and extends the
Long Term Evolution (LTE) stack for the higher layers. In this paper we present
an implementation for the ns-3 mmWave module of multi connectivity techniques
for 3GPP New Radio (NR) at mmWave frequencies, namely Carrier Aggregation (CA)
and Dual Connectivity (DC), and discuss how they can be integrated to increase
the functionalities offered by the ns-3 mmWave module.Comment: 9 pages, 7 figures, submitted to the Workshop on ns-3 (WNS3) 201
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