Considerations for low-power communication in industrial IoT applications

Of all the unlicensed spectrum LPWAN technologies it would appear that the LoRaWAN standard seems to be gaining the most market traction. The most cited reasons for choosing LoRaWAN is the large communication range and the wide ecosystem of compatible sensors and gateway equipment. By standardizing on a LoRaWAN network deployment, industrial customers hope to cover a large number of use cases with only a limited investment in shared infrastructure.

However, as always, there is no silver bullet technology, and this is certainly true in industrial IoT. In this document we will look into different application trade-offs and the underlying aspects responsible for these limitations. For instance, for meter reading type of applications (a reading being taken every hour) it might be acceptable to miss some messages, but other industrial use cases require better reliability, especially for control systems or safety related use cases. In addition to reliability we will also explore aspects like latency, scalability, bidirectional communication, multi-cast communication and legislation. We will be comparing (private) LoRaWAN and the DASH7 Alliance Protocol mainly in industrial IoT use cases.

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DASH7 Alliance Protocol 1.0: Low-Power, Mid-Range Sensor and Actuator Communication

Authors
Maarten Weyn, Glenn Ergeerts, Rafael Berkvens, Bartosz Wojciechowski, Yordan Tabakov

Abstract
This paper presents the DASH7 Alliance Protocol 1.0. It is an industry alliance standard for wireless sensor and actuator communication using the unlicensed sub-1 GHz bands. The paper explains its historic relation to active RFID standards ISO 18000-7 for 433 MHz communication, the basic concepts and communication paradigms of the protocol. Since the protocol is a full OSI stack specification, the paper discusses the implementation of every OSI layer.

DASH7 Alliance Protocol in Monitoring Applications

Authors
Glenn Ergeerts, Maciej Nikodem, Dragan Subotic, Tomasz Surmacz, Bartosz Wojciechowski, Paul De Meulenaere, Maarten Weyn

Abstract
In this paper we introduce important aspects of the recently published DASH7 Alliance Protocol v1.0 specification for wireless sensor and actuator networks. The main contribution of this paper is the discussion of the different communication schemes and the accompanying trade-offs which can be used when designing a DASH7 network. Finally, we describe two practical use cases as examples of how DASH7 can be used to efficiently solve specific problems as well as the hardware developed that uses energy harvesting.

Dash7 File Management System

Authors
Ronald Pulvermacher, Krzysztof Berezowski, Maarten Weyn, and Michael Andre

Abstract
Have you ever seen your developers struggle with outwardly simple distributed embedded application? Have you seen them deceived by its functional simplicity then combated and defeated by the complexity of power management, connectivity management, packet routing, message queuing, synchronization, you name it? DASH7 abstracts those nightmares away. This white paper illustrates how its file system based abstract take on the sensor network allows you to focus on the most important task of the connected embedded system you have at hand – producing and providing information.

Survey of the DASH7 Alliance Protocol for 433MHz Wireless Sensor Communication

Authors
Maarten Weyn, Glenn Ergeerts, Luc Wante, Charles Vercauteren, and Peter Hellinckx

Abstract
433 MHz is getting more attention for Machine-to-Machine communication. This paper presents the DASH7 Alliance Protocol, an active RFID alliance standard for 433 MHz wireless sensor communication based on the ISO/IEC 18000-7. First, the major differences of 433 MHz communication compared to more frequently used frequencies, such as 2.4 GHz and 868/920 MHz are explained. Subsequently, the general concepts of DASH7 Alliance Protocol are described, such as the BLAST networking topology and the different OSI layer implementations, in a top-down method. Basic DASH7 features such as the advertising protocol, ad-hoc synchronization and query based addressing are used to explain the different layers. Finally, the paper introduces a software stack implementation named OSS-7, which is an open source implementation of the DASH7 alliance protocol used for testing, rapid prototyping, and demonstrations

On the suitability of the 433 MHz band for M2M low-power wireless communications: propagation aspects

Authors
Pere Tuset-Peiró, Albert Anglès-Vazquez, José López-Vicario and Xavier Vilajosana-Guillén

Abstract
The 433 MHz band is gaining relevance as an alternative to the 2.4 GHz band for machine-to-machine communications using low-power wireless technologies. Currently, two standards are being developed that use the 433 MHz band, DASH7 Mode 2 and IEEE 802.15.4f. The article presents propagation models based on measurements conducted at the 433 MHz and 2.4 GHz bands that can be used for link budget calculations in both outdoor and indoor environments depending on node height. The results obtained show that the 433 MHz band has a larger communication range in both indoor and outdoor environments despite the negative effects of having a larger Fresnel zone. In addition, indoor propagation measurements are conducted in line-of-sight and nonline-of-sight conditions to determine the suitability of channel hopping to combat the effects of multipath propagation. Contrary to the 2.4 GHz band, the results show that channel hopping at 433 MHz does not provide any link robustness advantage because the channel coherence bandwidth is larger than the whole band bandwidth, and thus, all channels are highly correlated.

Performance Comparison of DASH7 and ISO/IEC 18000-7 for Fast Tag Collection with an Enhanced CSMA/CA Protocol

Authors
Hwakyung Lee, Sang-Hwa Chung, Yun-Sung Lee, Yoobin Ha

Abstract—ISO/IEC 18000-7 adopted Slotted ALOHA as MAC transmission protocol. However, this protocol cannot solve the collision problem when there is a need of collecting massive tags. To solve this problem, DASH7 adopted CSMA/CA for MAC protocol. It also proposed three kinds of collision avoidance models to implement the back off flexibly. AIND is the unsurpassed model as it can effectively use the contention period employing data transmission time back off. RAIND adopts random initialization and distribute access time of each tag in order to reduce the backoff. And the last, RIGD does geometric decaying slot backoff, minimizing the number of backoffs to reduce energy consumption. This paper presents tag collection scenario. We analyze the three CA models and Slotted ALOHA with tag collection time. We also suggest adaptive guard time method to improve the CA models. The aftermath of tag collection experiment is that CSMA/CA has exceptional performance than Slotted ALOHA. AIND has the best performance among CA models and its performance is 28.7% better than Slotted ALOHA. In addition, the adaptive guard time method enhances RAIND and RIGD which are based on random back-off. In particular, RIGD with adaptive guard time method(AG-RIGD) has similar performance as AIND. Besides, AG-RIGD is better than AIND in terms of energy efficiency because it consumes one third of energy than AIND during tag collection.