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CometOS

A component-based, extensible, tiny operating system for wireless networks

Start 1. January 2012

Project Description

CometOS is a component-based, extensible, tiny operating system for wireless networks. It is written in C++ and highly inspired by OMNeT++'s communication paradigm. It allows the execution of protocols within the OMNeT++ simulation environment as well as on resource-restricted platforms such as wireless sensor nodes.

The software is published at https://github.com/CometOS/CometOS and can be used under the terms of a 3-clause BSD-style license.

Key Features

Currently Supported platforms

To ease transition to other hardware platforms, we keep the interface to the hardware-dependent part as slim as possible. The core framework at minimum needs the implementation of a timer interface, needed by the scheduler to realize message passing (and providing millisecond-accuracy timers for the user). Furthermore, a generic MAC interface has to be implemented to provide high-level access to the transceiver and enable transmissions to the wireless channel.

Publications

Andreas Weigel and Volker Turau. Hardware-Assisted IEEE 802.15.4 Transmissions and Why to Avoid Them. In Conference proceedings of the 8th International Conference on Internet and Distributed Computer Systems, IDCS 2015, September 2015, pp. 223–234. Windsor, UK.
[BibTeX] [Abstract] [DOI] [Slides]
@InProceedings{Telematik_IDCS_2015_6LoWPAN, author = {Andreas Weigel and Volker Turau}, title = {Hardware-Assisted IEEE 802.15.4 Transmissions and Why to Avoid Them}, booktitle = {Conference proceedings of the 8th International Conference on Internet and Distributed Computer Systems, IDCS 2015}, pages = {223-234}, day = {2-4}, month = sep, year = 2015, location = {Windsor, UK}, }
Abstract: 6LoWPAN’s fragmentation mechanism enables transport of IPv6 datagrams with the required minimum MTU of 1280 bytes over IEEE 802.15.4-based networks. Testbed experiments showed disastrously bad datagram success rates for a collection traffic scenario with large, 6LoWPAN-fragmented datagrams, which significantly differed from the simulation results for a comparable scenario. In this paper we present an experimental setup that enables capturing the MAC and transceiver states of participating nodes in realtime. The results of our experiments show, that for the given fragmentation/collection scenario, the usage of the extended operating mode of the transceiver hardware, which provides CSMA/CA, ACKs and retransmissions in hardware, is responsible for nearly all datagram losses. Therefore, we strongly advise against using such hardware-assisted modes of operation in similar traffic scenarios.
Gerry Siegemund, Volker Turau and Christoph Weyer. A Dynamic Topology Control Algorithm for Wireless Sensor Networks. In Proceedings of the International Conference on Ad-hoc, Mobile and Wireless Networks, ADHOC-NOW 2015, June 2015, pp. 3–18. Athens, Greece.
[BibTeX] [Abstract] [DOI] [Slides]
@InProceedings{Telematik_Adhoc-Now_2015, author = {Gerry Siegemund and Volker Turau and Christoph Weyer}, title = {A Dynamic Topology Control Algorithm for Wireless Sensor Networks}, booktitle = {Proceedings of the International Conference on Ad-hoc, Mobile and Wireless Networks, ADHOC-NOW 2015}, pages = {3-18}, month = jun, year = 2015, location = {Athens, Greece}, }
Abstract: Topology control algorithms (TCAs) are used in wireless sensor networks to reduce interference by carefully choosing communication links. Since the quality of the wireless channel is subject to fluctuations over time TCAs must repeatedly recompute the topology. TCAs ensure quick adjustment to new or deteriorating links while preventing precipitant changes due to transient faults. This paper contributes a novel dynamic TCA that provides a compromise between agility and stability, and constructs connected topologies for low latency routing. Furthermore, it enforces memory restrictions and is of high practical relevance for real sensor network hardware.
Andreas Weigel, Martin Ringwelski, Volker Turau and Andreas Timm-Giel. Route-over forwarding techniques in a 6LoWPAN. EAI Endorsed Transactions on Mobile Communications and Applications, 14(5), December 2014.
[BibTeX] [Abstract] [DOI] [PDF]
@Article{Telematik_EAI_6LowPAN_2014, author = {Andreas Weigel and Martin Ringwelski and Volker Turau and Andreas Timm-Giel}, title = {Route-over forwarding techniques in a 6LoWPAN}, journal = {EAI Endorsed Transactions on Mobile Communications and Applications}, volume = {14}, number = {5}, month = dec, year = 2014, }
Abstract: 6LoWPAN plays a major role within the protocol stack for the future Internet of Things. Its fragmentation mechanism enables transport of IPv6 datagrams with the required minimum MTU of 1280 bytes over 802.15.4-based networks. With the goal of a fully standardized WSN protocol stack currently necessitating a route-over approach, i.e., routing at the IP-layer, there are two main choices for any 6LoWPAN implementation with regard to datagram fragmentation: Hop-by-hop assembly or a cross-layered direct mode, which forwards individual 6LoWPAN fragments before the whole datagram has arrived. In addition to these two straightforward approaches, we propose enhancements based on adaptive rate-restriction for the direct forwarding and a retry control for both modes to reduce the number of losses of larger datagrams. An evaluation of these modes in a simulation environment and a hardware testbed indicate that the proposed enhancements can considerably improve PRR and latency within 6LoWPAN networks.
Stefan Unterschütz and Volker Turau. Fail-Safe Over-The-Air Programming and Error Recovery in Wireless Networks. In Proceedings of the 10th Workshop on Intelligent Solutions in Embedded Systems (WISES'12), June 2012. Klagenfurt, Austria.
[BibTeX] [PDF]
@InProceedings{Telematik_UT_2012_OTAP, author = {Stefan Untersch{\"u}tz and Volker Turau}, title = {Fail-Safe Over-The-Air Programming and Error Recovery in Wireless Networks}, booktitle = {Proceedings of the 10th Workshop on Intelligent Solutions in Embedded Systems (WISES'12)}, day = {5-6}, month = jun, year = 2012, location = {Klagenfurt, Austria}, }
Stefan Unterschütz, Andreas Weigel and Volker Turau. Cross-Platform Protocol Development Based on OMNeT++. In Proceedings of the 5th International Workshop on OMNeT++ (OMNeT++'12), March 2012. Desenzano, Italy.
[BibTeX] [PDF] [Slides]
@InProceedings{Telematik_UWT_2012_CometOS, author = {Stefan Untersch{\"u}tz and Andreas Weigel and Volker Turau}, title = {Cross-Platform Protocol Development Based on OMNeT++}, booktitle = {Proceedings of the 5th International Workshop on OMNeT++ (OMNeT++'12)}, day = {23}, month = mar, year = 2012, location = {Desenzano, Italy}, }

Students' theses

Completed Theses