Enhanced Minimal Scheduling Function for IEEE 802.15.4e TSCH Networks

Hamza, Taieb; Kaddoum, Georges

doi:10.1109/wcnc.2019.8885940

Cited by 22 publications

(12 citation statements)

References 12 publications

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“…Apart from enhancing the Orchestra scheduler, Hamza et al [13] introduce an extension to the TSCH minimal scheduling function. The scheduler predicts the transmitted control data for each pair of nodes in the next slotframe and anticipates in that way to control overhead.…”

Section: B Tsch Schedulingmentioning

confidence: 99%

Adaptive multi-PHY IEEE802.15.4 TSCH in sub-GHz industrial wireless networks

et al. 2021

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To provide wireless coverage in challenging industrial environments, IEEE802.15.4 Time-Slotted Channel Hopping (TSCH) presents a robust medium access protocol. Using multiple Physical Layers (PHYs) could improve TSCH even more in these heterogeneous environments. However, TSCH only defines one fixed-duration timeslot structure allowing one packet transmission. Using multiple PHYs with various data rates therefore does not yield any improvements because of this single-packet limitation combined with a fixed slot duration. We therefore defined two alternative timeslot structures allowing multiple packets transmissions to increase the throughput for higher data rate PHYs while meeting a fixed slot duration. In addition, we developed a flexible Link Quality Estimation (LQE) technique to dynamically switch between PHYs depending on the current environment. This paper covers a theoretical evaluation of the proposed slot structures in terms of throughput, energy consumption and memory constraints backed with an experimental validation, using a proof-of-concept implementation, which includes topology and PHY switching. Our results show that a 153 % higher net throughput can be obtained with 84 % of the original energy consumption and confirm our theoretical evaluation with a 99 % accuracy. Additionally, we showed that in a real-life testbed of 33 nodes, spanning three floors and covering 2550 m 2 , a compact multi-PHY TSCH network can be formed. By distinguishing between reliable and high throughput PHYs, a maximum hop count of three was achieved with a maximum throughput of 219 kbps. Consequently, using multiple (dynamic) PHYs in a single TSCH network is possible while still being backwards compatible to the original fixed slot duration TSCH standard.

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Section: B Tsch Schedulingmentioning

confidence: 99%

Adaptive multi-PHY IEEE802.15.4 TSCH in sub-GHz industrial wireless networks

et al. 2021

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“…The distribution of the number of data packets

generated by each node in the network from the start of the slotframe to its end is calculated as follows [ 22 ]:

…”

Section: High Traffic Load Issuesmentioning

confidence: 99%

OSCAR: An Optimized Scheduling Cell Allocation Algorithm for Convergecast in IEEE 802.15.4e TSCH Networks

Mohamed

Nabki

2021

Sensors

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Today’s wireless sensor networks expect to receive increasingly more data from different sources. The Time Slotted Channel Hopping (TSCH) protocol defined in the IEEE 802.15.4-2015 version of the IEEE 802.15.4 standard plays a crucial role in reducing latency and minimizing energy consumption. In the case of convergecast traffic, nodes close to the root have consistently heavy traffic and suffer from severe network congestion problems. In this paper, we propose OSCAR, an novel autonomous scheduling TSCH cell allocation algorithm based on Orchestra. This new design differs from Orchestra by allocating slots according to the location of the node relative to the root. The goal of this algorithm is to allocate slots to nodes according to their needs. This algorithm manages the number of timeslots allocated to each node using the value of the rank described by the RPL routing protocol. The goal is that the closer the node is to the root, the more slots it gets in order to maximize the transmission opportunities. To avoid overconsumption, OSCAR sets up a mechanism to adjust the radio duty cycle of each node by reducing the slots allocated to inactive nodes regardless of their position in the network. We implement OSCAR on Contiki-ng and evaluate its performance by both simulations and experimentation. The performance assessment of OSCAR shows that it outperforms Orchestra on the average latency and reliability, without significantly increasing the average duty cycle, especially when the traffic load is high.

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“…Hamza and Kaddoum [ 36 ] provided an enhancement to the bandwidth allocation algorithm defined in MSF, called E-MSF, by computing the mean of packets generated by each node and using a Poisson-based prediction model for possible required cells in the next slotframe. Results show that E-MSF outperforms MSF in terms of end-to-end latency, because it constantly keeps probable cells scheduled in the slotframe, whether they are being used or not.…”

Section: Related Workmentioning

confidence: 99%

Distributed Channel Ranking Scheduling Function for Dense Industrial 6TiSCH Networks

Valdovinos

Millán

Díaz

et al. 2021

Sensors

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The Industrial Internet of Things (IIoT) is considered a key enabler for Industry 4.0. Modern wireless industrial protocols such as the IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) deliver high reliability to fulfill the requirements in IIoT by following strict schedules computed in a Scheduling Function (SF) to avoid collisions and to provide determinism. The standard does not define how such schedules are built. The SF plays an essential role in 6TiSCH networks since it dictates when and where the nodes are communicating according to the application requirements, thus directly influencing the reliability of the network. Moreover, typical industrial environments consist of heavy machinery and complementary wireless communication systems that can create interference. Hence, we propose a distributed SF, namely the Channel Ranking Scheduling Function (CRSF), for IIoT networks supporting IPv6 over the IEEE 802.15.4e TSCH mode. CRSF computes the number of cells required for each node using a buffer-based bandwidth allocation mechanism with a Kalman filtering technique to avoid sudden allocation/deallocation of cells. CRSF also ranks channel quality using Exponential Weighted Moving Averages (EWMAs) based on the Received Signal Strength Indicator (RSSI), Background Noise (BN) level measurements, and the Packet Delivery Rate (PDR) metrics to select the best available channel to communicate. We compare the performance of CRSF with Orchestra and the Minimal Scheduling Function (MSF), in scenarios resembling industrial environmental characteristics. Performance is evaluated in terms of PDR, end-to-end latency, Radio Duty Cycle (RDC), and the elapsed time of first packet arrival. Results show that CRSF achieves high PDR and low RDC across all scenarios with periodic and burst traffic patterns at the cost of increased end-to-end latency. Moreover, CRSF delivers the first packet earlier than Orchestra and MSF in all scenarios. We conclude that CRSF is a viable option for IIoT networks with a large number of nodes and interference. The main contributions of our paper are threefold: (i) a bandwidth allocation mechanism that uses Kalman filtering techniques to effectively calculate the number of cells required for a given time, (ii) a channel ranking mechanism that combines metrics such as the PDR, RSSI, and BN to select channels with the best performance, and (iii) a new Key Performance Indicator (KPI) that measures the elapsed time from network formation until the first packet reception at the root.

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Enhanced Minimal Scheduling Function for IEEE 802.15.4e TSCH Networks

Cited by 22 publications

References 12 publications

Adaptive multi-PHY IEEE802.15.4 TSCH in sub-GHz industrial wireless networks

Adaptive multi-PHY IEEE802.15.4 TSCH in sub-GHz industrial wireless networks

OSCAR: An Optimized Scheduling Cell Allocation Algorithm for Convergecast in IEEE 802.15.4e TSCH Networks

Distributed Channel Ranking Scheduling Function for Dense Industrial 6TiSCH Networks

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