472 research outputs found
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
Time4: Time for SDN
With the rise of Software Defined Networks (SDN), there is growing interest
in dynamic and centralized traffic engineering, where decisions about
forwarding paths are taken dynamically from a network-wide perspective.
Frequent path reconfiguration can significantly improve the network
performance, but should be handled with care, so as to minimize disruptions
that may occur during network updates.
In this paper we introduce Time4, an approach that uses accurate time to
coordinate network updates. Time4 is a powerful tool in softwarized
environments, that can be used for various network update scenarios.
Specifically, we characterize a set of update scenarios called flow swaps, for
which Time4 is the optimal update approach, yielding less packet loss than
existing update approaches. We define the lossless flow allocation problem, and
formally show that in environments with frequent path allocation, scenarios
that require simultaneous changes at multiple network devices are inevitable.
We present the design, implementation, and evaluation of a Time4-enabled
OpenFlow prototype. The prototype is publicly available as open source. Our
work includes an extension to the OpenFlow protocol that has been adopted by
the Open Networking Foundation (ONF), and is now included in OpenFlow 1.5. Our
experimental results show the significant advantages of Time4 compared to other
network update approaches, and demonstrate an SDN use case that is infeasible
without Time4.Comment: This report is an extended version of "Software Defined Networks:
It's About Time", which was accepted to IEEE INFOCOM 2016. A preliminary
version of this report was published in arXiv in May, 201
Survey of Consistent Network Updates
Computer networks have become a critical infrastructure. Designing dependable computer networks however is challenging, as such networks should not only meet strict requirements in terms of correctness, availability, and performance, but they should also be flexible enough to support fast updates, e.g., due to a change in the security policy, an increasing traffic demand, or a failure. The advent of Software-Defined Networks (SDNs) promises to provide such flexiblities, allowing to update networks in a fine-grained manner, also enabling a more online traffic engineering. In this paper, we present a structured survey of mechanisms and protocols to update computer networks in a fast and consistent manner. In particular, we identify and discuss the different desirable update consistency properties a network should provide, the algorithmic techniques which are needed to meet these consistency properties, their implications on the speed and costs at which updates can be performed. We also discuss the relationship of consistent network update problems to classic algorithmic optimization problems. While our survey is mainly motivated by the advent of Software-Defined Networks (SDNs), the fundamental underlying problems are not new, and we also provide a historical perspective of the subject
SDT: A Low-cost and Topology-reconfigurable Testbed for Network Research
Network experiments are essential to network-related scientific research
(e.g., congestion control, QoS, network topology design, and traffic
engineering). However, (re)configuring various topologies on a real testbed is
expensive, time-consuming, and error-prone. In this paper, we propose
\emph{Software Defined Topology Testbed (SDT)}, a method for constructing a
user-defined network topology using a few commodity switches. SDT is low-cost,
deployment-friendly, and reconfigurable, which can run multiple sets of
experiments under different topologies by simply using different topology
configuration files at the controller we designed. We implement a prototype of
SDT and conduct numerous experiments. Evaluations show that SDT only introduces
at most 2\% extra overhead than full testbeds on multi-hop latency and is far
more efficient than software simulators (reducing the evaluation time by up to
2899x). SDT is more cost-effective and scalable than existing Topology
Projection (TP) solutions. Further experiments show that SDT can support
various network research experiments at a low cost on topics including but not
limited to topology design, congestion control, and traffic engineering.Comment: This paper will be published in IEEE CLUSTER 2023. Preview version
onl
A Case for Time Slotted Channel Hopping for ICN in the IoT
Recent proposals to simplify the operation of the IoT include the use of
Information Centric Networking (ICN) paradigms. While this is promising,
several challenges remain. In this paper, our core contributions (a) leverage
ICN communication patterns to dynamically optimize the use of TSCH (Time
Slotted Channel Hopping), a wireless link layer technology increasingly popular
in the IoT, and (b) make IoT-style routing adaptive to names, resources, and
traffic patterns throughout the network--both without cross-layering. Through a
series of experiments on the FIT IoT-LAB interconnecting typical IoT hardware,
we find that our approach is fully robust against wireless interference, and
almost halves the energy consumed for transmission when compared to CSMA. Most
importantly, our adaptive scheduling prevents the time-slotted MAC layer from
sacrificing throughput and delay
Airborne Directional Networking: Topology Control Protocol Design
This research identifies and evaluates the impact of several architectural design choices in relation to airborne networking in contested environments related to autonomous topology control. Using simulation, we evaluate topology reconfiguration effectiveness using classical performance metrics for different point-to-point communication architectures. Our attention is focused on the design choices which have the greatest impact on reliability, scalability, and performance. In this work, we discuss the impact of several practical considerations of airborne networking in contested environments related to autonomous topology control modeling. Using simulation, we derive multiple classical performance metrics to evaluate topology reconfiguration effectiveness for different point-to-point communication architecture attributes for the purpose of qualifying protocol design elements
eHDDP: Enhanced Hybrid Domain Discovery Protocol for network topologies with both wired/wireless and SDN/non-SDN devices
Handling efficiently both wired and/or wireless devices in SDN networks is still an open issue. eHDDP comes as an enhanced version of the Hybrid Domain Discovery Protocol (HDDP) that allows the SDN control plane to discover and manage hybrid topologies composed by both SDN and non-SDN devices with wired and/or wireless interfaces, thus opening a path for the integration of IoT and SDN networks. Moreover, the proposal is also able to detect both unidirectional and bidirectional links between wireless devices. eHDDP has been thoroughly evaluated in different scenarios and exhibits good scalability properties since the number of required messages is proportional to the number of existing links in the network topology. Moreover, the obtained discovery and processing times give the opportunity to support scenarios with low mobility devices since the discovery times are in the range of hundreds of milliseconds.Comunidad de MadridJunta de Comunidades de Castilla-La Manch
LTE Handover performance evaluation based on power budget handover algorithm
LTE (Long Term Evolution) is a fourth generation cellular network technology that provides improved performance related to data rate, coverage and capacity compared to legacy cellular systems. In this context, one of the main goals of LTE is to provide fast and seamless handover from one cell to another to meet a strict delay requirement while simultaneously keeping network management simple. Hence, the decision to trigger a handover is a crucial component in the design process of handover, since the success and the efficiency, to a large extent, depends on the accuracy and timeliness of the decision. The design of an efficient and successful handover requires a careful selection of HO parameters and the optimal setting of these. The LTE standard supports two parameters to trigger the handover and select the target cell: hysteresis margin and Time-to-Trigger (TTT) The research topic of this thesis which is “LTE Handover Performance Evaluation Based on Power Budget Handover Algorithm”, focuses on different combinations or settings of HOM and TTT values to evaluate the handover performance based on Reference Signal Received Power (RSRP) measurement within certain deployment scenarios, such as different UE speeds, system loads and cell sizes. The Power Budget Handover Algorithm (PBHA) picks the best hysteresis and time-to-trigger combinations to evaluate the system performance in terms of number of handovers, signal-to-interference plus noise ratio (SINR), throughput, delay and packet lost for UE's which are about to perform the handover
- …