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Publications

Publications by Hélder Martins Fontes

2015

Improving ns-3 emulation support in real-world networking scenarios

Authors
Fontes, H; Campos, R; Ricardo, M;

Publication
Proceedings of the 8th International Conference on Simulation Tools and Techniques, Athens, Greece, August 24-26, 2015

Abstract
A common problem in networking research and development is the duplicate effort of writing simulation and implementation code. This duplication can be avoided through the use of fast-prototyping methodologies, which enable reusing simulation code in real prototyping and in production environments. Although this functionality is already available by using ns-3 emulation, there are still limitations regarding the support of real network interfaces and easy configuration of the network settings, such as IP and MAC addresses. In this paper we propose an improved version of the ns-3 emulation component by introducing new functionalities that address these limitations. The new functionalities include the support of new types of real network interfaces and the easier integration of emulation nodes with existing networks by means of a new auto-configuration mechanism for ns-3 nodes. Experimental results obtained in a laboratorial testbed and in a real vehicular network testbed demonstrate the new functionalities proper operation, and their backwards compatibility with previously coded ns-3 scenarios. Copyright © 2015 ICST.

2017

A Trace-based ns-3 Simulation Approach for Perpetuating Real-World Experiments

Authors
Fontes, H; Campos, R; Ricardo, M;

Publication
Proceedings of the Workshop on ns-3, Porto, Portugal, June 13 - 14, 2017

Abstract
A common problem in mobile networking research and development is the cost related to deploying and running real-world mobile testbeds. Due to cost and operational constraints, these testbeds usually run for short time periods but generate very unique and relevant results that are hard to reproduce. We propose the use of ns-3 as a solution to successfully reproduce real-world mobile testbed experiments. This is accomplished by feeding ns-3 with real testbed traces including node positions and radio link quality only. In order to validate our approach, the network throughput between a fixed Base Station and a Unmanned Aerial Vehicle (UAV) was measured in a real-world testbed. The experimental results were compared to the network throughput achieved using the ns-3 trace-based simulation and a plain ns-3 simulation. The obtained results show the high accuracy of the trace-based simulation, thus validating our approach. © 2017 ACM.

2016

Improving ns-3 Emulation Performance for Fast Prototyping of Network Protocols

Authors
Fontes, H; Cardoso, T; Ricardo, M;

Publication
Proceedings of the Workshop on ns-3, WNS3 '16, Seattle, WA, USA, June 15-16, 2016

Abstract
A common problem in networking research and development is the duplicate effort of writing simulation and implementation code of network protocols. This duplication can be avoided through the use of fast prototyping development processes, which enable reusing simulation code in real prototyping and in production environments. Although this functionality is already available by using ns-3 emulation, there are still limitations regarding the additional packet processing that emulation introduces, which degrades the node’s performance and limits the amount of network traffic that can be processed. In this paper we propose an approach to reduce the performance problem associated with fast prototyping that consists in migrating data plane operations processing to outside of ns-3. In a well-designed network, most of the traffic should be data. By moving the data plane operations outside of ns-3 the overhead associated with this kind of traffic is greatly reduced, while control plane protocols may still be reused. In order to validate our proposed solution, we extended the Wireless Metropolitan Routing Protocol (WMRP) and Optimized Link State Routing (OLSR) protocols to use the developed architecture, tested their performance in real environments, and verified the amount of code reuse between the simulator and the real system. © 2016 ACM.

2018

Improving the ns-3 TraceBasedPropagationLossModel to Support Multiple Access Wireless Scenarios

Authors
Fontes, H; Campos, R; Ricardo, M;

Publication
WORKSHOP ON NETWORK SIMULATOR (NS)-3 (WNS3 2018)

Abstract
In wireless networking R&D we typically depend on experimentation to further evaluate a solution, as simulation is inherently a simplification of the real-world. However, experimentation is limited in aspects where simulation excels, such as repeatability and reproducibility. Real wireless experiments are hardly repeatable. Given the same input they can produce very different output results, since wireless communications are influenced by external random phenomena such as noise, interference, and multipath. Real experiments are also difficult to reproduce due to testbed operational constraints and availability. We have previously proposed the Trace-based Simulation (TS) approach, which uses the TraceBasedPropagationLossModel to successfully reproduce past experiments. Yet, in its current version, the TraceBasedPropagationLossModel only supports point-to-point scenarios. In this paper, we introduce a new version of the model that supports Multiple Access wireless scenarios. To validate the new version of the model, the network throughput was measured in a laboratory testbed. The experimental results were then compared to the network throughput achieved using the ns-3 trace-based simulation and a pure ns-3 simulation, confirming the TS approach is valid for multiple access scenarios too.

2017

UAV cooperative perception based on DDS communications network

Authors
Ribeiro, JP; Fontes, H; Lopes, M; Silva, H; Campos, R; Almeida, JM; Silva, E;

Publication
OCEANS 2017 - Anchorage

Abstract
This paper focus on the use of unmanned aerial vehicle teams for performing cooperative perception using Data Distribution Service (DDS) Network. We develop a DDS framework to manage the incoming and out bounding network traffic of multiple types of data that is exchanged inside the UAV network. Experimental results both in laboratory and in actual flight are presented to help characterize the proposed system solution. © 2017 Marine Technology Society.

2019

Improving ns-3 emulation performance for fast prototyping of routing and SDN protocols: Moving data plane operations to outside of ns-3

Authors
Fontes, H; Cardoso, T; Campos, R; Ricardo, M;

Publication
SIMULATION MODELLING PRACTICE AND THEORY

Abstract
A common problem in networking research and development is the duplicate effort of writing simulation and implementation code of routing protocols. This can be avoided by reusing simulation code in real prototyping and in production environments. In ns-3, emulation mode can be used to run simulation models of routing and Software Defined Networking (SDN) protocols on top of real L2 interfaces such as Ethernet and Wi-Fi. Although this feature is already available, the additional packet processing involved degrades the performance of the nodes and limits the amount of network traffic that can be processed. Our proposal to overcome this performance bottleneck consists in moving the data plane processing operations to outside of the ns-3 process, running such operations natively in the host Operating System (OS). Two approaches are proposed: (a) running the data plane in user space (DPU); (b) running the data plane in kernel space (DPK). Both approaches support the emulation of one or multiple nodes per emulation host machine. The experimental results show that the DPU and DPK approaches significantly improve the throughput by respectively 4.9 and 19 times when compared against traditional ns-3 emulation of a single node. For multiple nodes, the DPK approach further improves the throughput by as much as 23 times. The amount of code reuse is high - e.g., for the routing protocols used in this paper, only 1.4% and 11% of extra code is required to benefit from the performance improvements achieved respectively by the DPK and DPU approaches.

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