| 1. |
- Al Nahas, Beshr, 1985, et al.
(författare)
-
Low-power listening goes multi-channel
- 2014
-
Ingår i: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2014. ; , s. 2-9
-
Konferensbidrag (refereegranskat)abstract
- Exploiting multiple radio channels for communication has been long known as a practical way to mitigate interference in wireless settings. In Wireless Sensor Networks, however, multi-channel solutions have not reached their full potential: the MAC layers included in TinyOS or the Contiki OS for example are mostly single-channel. The literature offers a number of interesting solutions, but experimental results were often too few to build confidence. We propose a practical extension of low-power listening, MiCMAC, that performs channel hopping, operates in a distributed way, and is independent of upper layers of the protocol stack. The above properties make it easy to deploy in a variety of scenarios, without any extra configuration/scheduling/channel selection hassle. We implement our solution in Contiki and evaluate it in a 97-node~testbed while running a complete, out-of-the-box low-power IPv6 communication stack (UDP/RPL/6LoWPAN). Our experimental results demonstrate increased resilience to emulated WiFi interference (e.g., data yield kept above 90% when Contiki MAC drops in the 40% range). In noiseless environments, MiCMAC keeps the overhead low in comparison to Contiki MAC, achieving performance as high as 99% data yield along with sub-percent duty cycle and sub-second latency for a 1-minute inter-packet interval data collection. © 2014 IEEE.
|
|
| 2. |
- De Guglielmo, Domenico, et al.
(författare)
-
Analysis and Experimental Evaluation of IEEE 802.15.4e TSCH CSMA-CA Algorithm
- 2017
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 66:2, s. 1573-1588
-
Tidskriftsartikel (refereegranskat)abstract
- Time-slotted channel hopping (TSCH) is one of the medium access control (MAC) behavior modes defined in the IEEE 802.15.4e standard. It combines time-slotted access and channel hopping, thus providing predictable latency, energy efficiency, communication reliability, and high network capacity. TSCH provides both dedicated and shared links. The latter is special slots assigned to more than one transmitter, whose concurrent access is regulated by a carrier-sense multiple access with collision avoidance (CSMA-CA) algorithm. In this paper, we develop an analytical model of the TSCH CSMA-CA algorithm to predict the performance experienced by nodes when using shared links. The model allows for deriving a number of metrics, such as delivery probability, packet latency, and energy consumption of nodes. Moreover, it considers the capture effect (CE) that typically occurs in real wireless networks. We validate the model through simulation experiments and measurements in a real testbed. Our results show that the model is very accurate. Furthermore, we found that the CE plays a fundamental role as it can significantly improve the performance experienced by nodes.
|
|
| 3. |
- Dron, Wilfried, et al.
(författare)
-
An Emulation-based Method for Lifetime Estimation of Wireless Sensor Networks
- 2014. - 9
-
Konferensbidrag (refereegranskat)abstract
- Lifetime estimation in Wireless Sensor Networks (WSN) is crucial to ensure that the network will last long enough (low maintenance cost) while not being over-dimensioned (low initial cost). Existing solutions have at least one of the two following limitations: (1) they are based on theoretical models or high-level protocol implementations, overlooking low-level (e.g., hardware, driver, etc.) constraints which we find have a significant impact on lifetime, and (2) they use an ideal battery model which over-estimates lifetime due to its constant voltage and its inability to model the non-linear properties of real batteries. We introduce a method for WSN lifetime estimation that operates on compiled firmware images and models the complex behavior of batteries. We use the MSPSim/Cooja node emulator and network simulator to run the application in a cycle-accurate manner and log all component states. We then feed the log into our lifetime estimation framework, which models the nodes and their batteries based on both technical and experimental specifications. In a case study of a Contiki RPL/6LoWPAN application, we identify and resolve several low-level implementation issues, thereby increasing the predicted network lifetime from 134 to 484 days. We compare our battery model to the ideal battery model and to the lifetime estimation based on the radio duty cycle, and find that there is an average over-estimation of 36% and 76% respectively.
|
|
| 4. |
- Hewage, Kasun, et al.
(författare)
-
Enabling TCP in Mobile Cyber-physical Systems
- 2015. - 7
-
Ingår i: 2015 IEEE 12th International Conference on Mobile Ad Hoc and Sensor Systems. - : IEEE Computer Society. - 9781467391016 ; , s. 289-297
-
Konferensbidrag (refereegranskat)abstract
- Cyber-physical systems consist of several wirelessly connected components such as sensors that monitor physical phenomena, computational entities that make decisions based on sensed information and actuators that interact with physical processes. Connecting cyber-physical systems to the Internet using IP protocols increases interoperability by avoiding the need for protocol translation gateways. Unfortunately, in this context TCP has been disregarded since it is known to perform poorly in wireless scenarios as it treats packet loss as an indicator for network congestion rather than poor link quality. In this paper, we use the Low-power Wireless Bus (LWB) as a link layer for TCP/IP, taking advantage of its reliability and its routing-free communication. We design a system that integrates LWB with a low-power IP stack and includes TCP-aware schedulers for LWB. We evaluate our system with experiments on real hardware using uIP, a popular embedded Internet protocol stack. Our results demonstrate high TCP throughput in mobile and static scenarios and, furthermore, show that mobility does not decrease TCP performance.
|
|
| 5. |
- Martina, Brachmann, et al.
(författare)
-
IEEE 802.15. 4 TSCH in Sub-GHz : Design Considerations and Multi-band Support
- 2019
-
Ingår i: Proceedings of the IEEE LCN. - : IEEE COMPUTER SOC. - 9781728110288 ; , s. 42-50
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we address the support of Time-Slotted Channel Hopping (TSCH) on multiple frequency bandswithin a single TSCH network. This allows to simultaneously runapplications with different requirements on link characteristicsand to increase resilience against interference. To this end, wefirst enable sub-GHz communication in TSCH, which has beenprimarily defined for the 2.4 GHz band. Thereafter, we proposetwo designs to support multiple physical layers in TSCH on thesame nodes. Our experimental evaluation shows that TSCH isapplicable in a wide range of data rates between 1.2 kbps and1000 kbps. We find that data rates of 50 kbps and below have along communication range and a nearly perfect link symmetry,but also have a 20x higher channel utilization compared to higherdata rates, increasing the risk of collisions. Using these findings,we show the advantages of the multi-band support on the exampleof synchronization accuracy when exchanging TSCH beaconswith a low data rate and application data at a high data rate.
|
|
| 6. |
- Michel, Mathieu, et al.
(författare)
-
Load-Balanced Data Collection through Opportunistic Routing
- 2015. - 9
-
Ingår i: 2015 International Conference on Distributed Computing in Sensor Systems. - 9781479988563 ; , s. 62-70
-
Konferensbidrag (refereegranskat)abstract
- Wireless Sensor Networks performing low-power data collection often suffer from uneven load distribution among nodes. Nodes close to the network root typically face a higher load, see their battery deplete first, and become prematurely unable to operate (both sensing and relaying other nodes' data). We argue that opportunistic routing, by making forwarding decision on a per-packet basis and at the receiver rather than the sender, has the potential to better balance the load across nodes. We extend ORPL, an opportunistic version of the standard routing protocol RPL, with support for load-balancing. In our protocol, ORPL-LB, nodes continuously adapt their wake-up interval in order to adjust their availability and attain a deployment-specific target duty cycle. We implement our protocol in Contikiand present our experimental validation in Indriya, a 93-nodestestbed. Our results show that ORPL-LB reduces significantly(by approximately 40%) the worst node's duty cycle, with little or no impact on packet delivery ratio and latency.
|
|
| 7. |
- Oikonomou, George, et al.
(författare)
-
The Contiki-NG open source operating system for next generation IoT devices
- 2022
-
Ingår i: SoftwareX. - : Elsevier B.V.. - 2352-7110. ; 18
-
Tidskriftsartikel (refereegranskat)abstract
- Contiki-NG (Next Generation) is an open source, cross-platform operating system for severely constrained wireless embedded devices. It focuses on dependable (reliable and secure) low-power communications and standardised protocols, such as 6LoWPAN, IPv6, 6TiSCH, RPL, and CoAP. Its primary aims are to (i) facilitate rapid prototyping and evaluation of Internet of Things research ideas, (ii) reduce time-to-market for Internet of Things applications, and (iii) provide an easy-to-use platform for teaching embedded systems-related courses in higher education. Contiki-NG started as a fork of the Contiki OS and retains many of its original features. In this paper, we discuss the motivation behind the creation of Contiki-NG, present the most recent version (v4.7), and highlight the impact of Contiki-NG through specific examples. © 2022 The Authors
|
|
| 8. |
- PrithviRaj, Narenda, et al.
(författare)
-
BLE and IEEE 802.15.4 in the IoT : Evaluation and Interoperability Considerations
- 2016
-
Ingår i: Internet Of Things. - Cham : Springer International Publishing. - 9783319470757 - 9783319470740 ; , s. 427-438
-
Konferensbidrag (refereegranskat)abstract
- As the Internet of Things is gaining momentum, low-power communication technologies proliferate. In this paper, we focus on Bluetooth Low Energy (BLE) and IEEE 802.15.4 (CSMA, Low-power listening, and TSCH), and advocate low-power IPv6 for interoperability between the two. We perform a thorough experimental comparison of their link-layer performance, both in idle radio environment and when facing heavy (controlled) external interference. Our results suggest that both technologies can achieve interesting and complementary latency-energy trade-offs. Based on our results, we discuss possible interoperability between BLE and IEEE 802.15.4 and present related open issues.
|
|
