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Item type:Publication, Access status: without files , Resource allocation strategies in multi-hop wireless networks for industrial applicationsPublicationtype: Doctoral Thesis40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Comparison of WiFi interference mitigation strategies in DSME networks: Leveraging reinforcement learning with expected SARSAIEEE 802.15.4 Deterministic and Synchronous Multichannel Extension (DSME) networks have demonstrated their robustness in industrial environments, particularly in data collection scenarios. However, their performance in coexistence with other wireless technologies, such as WiFi, remains largely unexplored. In this work, we perform a simulation analysis using the OpenDSME framework to evaluate the effect of WiFi interference on a DSME network for data collection, considering different channel diversity mechanisms. The proposed strategies include an overprovisioning scheme and the adoption of the recently proposed virtual sink strategy to countermeasure the inherent funnel effect.Our findings indicate that, in general, channel adaptation outperforms channel hopping, except in scenarios with high transmission rates and limited resources, where channel hopping is more effective. When comparing the proposed strategies, the frequency selection algorithm based on reinforcement learning using Expected State-Action-Reward-State-Action (SARSA) demonstrates the most favorable overall performance in the presence of WiFi interference.Publicationtype: Conference Paper15 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A comprehensive performance comparison of IEEE 802.15.4 DSME and TSCH in a realistic IoT scenario for industrial applications(2023-06-19); ; In the Industrial Internet of Things (i.e., IIoT), the standardization of open technologies and protocols has achieved seamless data exchange between machines and other physical systems from different manufacturers. At the MAC sublayer, the industry-standard protocols IEEE 802.15.4 Time Slot Channel Hopping (TSCH) and Deterministic and Synchronous Multi-channel Extension (DSME) show promising properties for high adaptability and dynamically changing traffic. However, performance comparison between these MAC protocols rarely has gone beyond a simulation phase. This work presents the results of such a comparison on physically deployed networks using the facilities of the FIT-IoTLab. The evaluation includes fully implementing an IIoT protocol stack based on MQTT in Contiki-NG. It comprises the integration of DSME as part of Contiki-NG's software stack through OpenDSME, the only publicly available implementation of DSME. Results show that both protocols suit IIoT applications, particularly for data collection. The comparison between TSCH and DSME also includes an evaluation of distributed schedulers for both MAC modes and one autonomous scheduler for TSCH within a UDP protocol stack.Publicationtype: Journal Article65 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Virtual Sink-based Strategy for Reducing the Funneling Effect in IEEE 802.15.4 DSME Networks(2022-06); The MAC protocol IEEE 802.15.4 DSME has features for WSNs to support exigent requirements such as high reliability and adaptability to dynamic traffic. This work introduces the concept of a virtual sink, which comprises the sink and its 1-hop neighbors, a.k.a. satellites, as the core of a strategy to alleviate the burden caused by the funneling effect in data collection scenarios. Our strategy enables the coexistence of a centralized scheduling algorithm at the virtual sink and a decentralized scheduling algorithm for the remaining nodes of the network. Through a simulative assessment, we compare the performance of the virtual sink-based strategy with the status quo of DSME via a decentralized slot scheduler TPS. Results show an improvement of the network throughput of up to 38% and a reduction of the energy consumption of about 30% at satellites.Publicationtype: Conference Paper20 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Sending multiple packets per guaranteed time slot in IEEE 802.15.4 DSME : analysis and evaluationCoping with bursty traffic is a common yet challenging task in the industrial Internet of Things (IoT). For example, 6LoWPAN is a standard that defines the integration of LoWPAN with IPv6, by fragmenting large IPv6 packets into several smaller MAC‐layer packets. Therefore, it is necessary to envision message delivery mechanisms, which provide support for highly varying traffic. In this paper, we analyze sending multiple packets per guaranteed time slot (GTS) in IEEE 802.15.4 DSME to alleviate traffic during the contention‐access period (CAP) and increase the reliability in scenarios with bursty traffic. The evaluation shows that increasing parameter SO extends the network throughput beyond default operating conditions and also provides overprovisioning beneficial for delivering sporadic messages. A comparison with the transmission of a single packet per GTS demonstrates a reduction of the total number of transmitted CAP messages by 99% while increasing the packet reception ratio by 48% for bursts with 20 packets.Publicationtype: Journal ArticleScopus© Citations 5 95 102 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , New CAP Reduction Mechanisms for IEEE 802.15.4 DSME to Support Fluctuating Traffic in IoT SystemsIn 2015, the IEEE 802.15.4 standard was expanded by the Deterministic and Synchronous Multi-Channel Extension (DSME) to increase reliability, scalability and energy-efficiency in industrial applications. The extension offers a TDMA/FDMA-based channel access, where time is divided into two alternating phases, a contention access period (CAP) and a contention free period (CFP). During the CAP, transmission slots can be allocated offering an exclusive access to the shared medium during the CFP. The fraction of CFP’s time slots in a dataframe is a critical value, because it directly influences agility and throughput. A high throughput demands that the CFP is much longer than the CAP, i.e., a high value of tau, because application data is only sent during the CFP. High agility is given if the expected waiting time to send a CAP message is short and that the length of the CAPs are long enough to accommodate necessary GTS negotiations, i.e., a low value of tau. Once DSME is configured according to the needs of an application, tau can only assume one of two values and cannot be changed at run-time. In this paper, we propose two extensions of DSME that allow to adopt tau to the current traffic pattern. We show theoretically and through simulations that the proposed extensions provide a high degree of responsiveness to traffic fluctuations while keeping the throughput high.Publicationtype: Conference Paper71 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Performance Analysis of the Slot Allocation Handshake in IEEE 802.15.4 DSMEWireless mesh networks using IEEE 802.15.4 are getting increasingly popular for industrial applications because of low energy consumption and low maintenance costs. The IEEE 802.15.4 standard introduces DSME (Deterministic and Synchronous Multi-channel Extension). DSME uses time-slotted channel access to guarantee timely data delivery, multi-channel communication, and frequency hopping to mitigate the effects of external interferences. A distinguishing feature of DSME is its flexibility and adaptability to time-varying network traffic and to changes in the network topology. In this paper we evaluate the ability of DSME to adapt to time-varying network traffic. We examine the limits for slot allocation rates for different topologies. The evaluation is performed with openDSME, an open-source implementation of DSME.Publicationtype: Conference Paper188