2,316 research outputs found
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
Performance Comparison of Dual Connectivity and Hard Handover for LTE-5G Tight Integration
Communications at frequencies above 10 GHz (the mmWave band) are expected to
play a major role for the next generation of cellular networks (5G), because of
the potential multi-gigabit, ultra-low latency performance of this technology.
mmWave frequencies however suffer from very high isotropic pathloss, which may
result in cells with a much smaller coverage area than current LTE macrocells.
High directionality techniques will be used to improve signal quality and
extend coverage area, along with a high density deployment of mmWave base
stations (BS). However, when propagation conditions are hard and it is
difficult to provide high quality coverage with mmWave BS, it is necessary to
rely on previous generation LTE base stations, which make use of lower
frequencies (900 MHz - 3.5 GHz), which are less sensitive to blockage and
experience lower pathloss. In order to provide ultra-reliable services to
mobile users there is a need for network architectures that tightly and
seamlessly integrate the LTE and mmWave Radio Access Technologies. In this
paper we will present two possible alternatives for this integration and show
how simulation tools can be used to assess and compare their performance.Comment: This paper was accepted for presentation at the ninth EAI SIMUtools
2016 conference, August 22 - 23, 2016, Prague, Czech Republi
Performance Comparison of Dual Connectivity and Hard Handover for LTE-5G Tight Integration in mmWave Cellular Networks
MmWave communications are expected to play a major role in the Fifth
generation of mobile networks. They offer a potential multi-gigabit throughput
and an ultra-low radio latency, but at the same time suffer from high isotropic
pathloss, and a coverage area much smaller than the one of LTE macrocells. In
order to address these issues, highly directional beamforming and a very
high-density deployment of mmWave base stations were proposed. This Thesis aims
to improve the reliability and performance of the 5G network by studying its
tight and seamless integration with the current LTE cellular network. In
particular, the LTE base stations can provide a coverage layer for 5G mobile
terminals, because they operate on microWave frequencies, which are less
sensitive to blockage and have a lower pathloss. This document is a copy of the
Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr.
Marco Mezzavilla and Prof. Michele Zorzi. It will propose an LTE-5G tight
integration architecture, based on mobile terminals' dual connectivity to LTE
and 5G radio access networks, and will evaluate which are the new network
procedures that will be needed to support it. Moreover, this new architecture
will be implemented in the ns-3 simulator, and a thorough simulation campaign
will be conducted in order to evaluate its performance, with respect to the
baseline of handover between LTE and 5G.Comment: Master's Thesis carried out by Mr. Michele Polese under the
supervision of Dr. Marco Mezzavilla and Prof. Michele Zorz
Evaluation, Modeling and Optimization of Coverage Enhancement Methods of NB-IoT
Narrowband Internet of Things (NB-IoT) is a new Low Power Wide Area Network
(LPWAN) technology released by 3GPP. The primary goals of NB-IoT are improved
coverage, massive capacity, low cost, and long battery life. In order to
improve coverage, NB-IoT has promising solutions, such as increasing
transmission repetitions, decreasing bandwidth, and adapting the Modulation and
Coding Scheme (MCS). In this paper, we present an implementation of coverage
enhancement features of NB-IoT in NS-3, an end-to-end network simulator. The
resource allocation and link adaptation in NS-3 are modified to comply with the
new features of NB-IoT. Using the developed simulation framework, the influence
of the new features on network reliability and latency is evaluated.
Furthermore, an optimal hybrid link adaptation strategy based on all three
features is proposed. To achieve this, we formulate an optimization problem
that has an objective function based on latency, and constraint based on the
Signal to Noise Ratio (SNR). Then, we propose several algorithms to minimize
latency and compare them with respect to accuracy and speed. The best hybrid
solution is chosen and implemented in the NS-3 simulator by which the latency
formulation is verified. The numerical results show that the proposed
optimization algorithm for hybrid link adaptation is eight times faster than
the exhaustive search approach and yields similar latency
TCP in 5G mmWave Networks: Link Level Retransmissions and MP-TCP
MmWave communications, one of the cornerstones of future 5G mobile networks,
are characterized at the same time by a potential multi-gigabit capacity and by
a very dynamic channel, sensitive to blockage, wide fluctuations in the
received signal quality, and possibly also sudden link disruption. While the
performance of physical and MAC layer schemes that address these issues has
been thoroughly investigated in the literature, the complex interactions
between mmWave links and transport layer protocols such as TCP are still
relatively unexplored. This paper uses the ns-3 mmWave module, with its channel
model based on real measurements in New York City, to analyze the performance
of the Linux TCP/IP stack (i) with and without link-layer retransmissions,
showing that they are fundamental to reach a high TCP throughput on mmWave
links and (ii) with Multipath TCP (MP-TCP) over multiple LTE and mmWave links,
illustrating which are the throughput-optimal combinations of secondary paths
and congestion control algorithms in different conditions.Comment: 6 pages, 11 figures, accepted for presentation at the 2017 IEEE
Conference on Computer Communications Workshops (INFOCOM WKSHPS
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