Dependable Embedded Wireless Infrastructure

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The DEWI high-level architecture: Wireless sensor networks in industrial applications

Publication . Samano-Robles, Ramiro; Nordstrom, Tomas; Santonja, Salvador; Rom, Werner; Tovar, Eduardo

This paper presents the high-level architecture (HLA) of the research project DEWI (dependable embedded wireless infrastructure). The objective of this HLA is to serve as a reference for the development of industrial wireless sensor and actuator networks (WSANs) based on the concept of the DEWI Bubble. The DEWI Bubble is defined here as a high-level abstraction of an industrial WSAN with enhanced interoperability (via standardized interfaces), technology reusability, and cross-domain development. This paper details the design criteria used to define the HLA and the organization of the infrastructure internal and external to the DEWI Bubble. The description includes the different perspectives, models or views of the architecture: the entity model, the layered model, and the functional view model (including an overview of interfaces). The HLA constitutes an extension of the ISO/IEC SNRA (sensor network reference architecture) towards the support of industrial applications. To improve interoperability with existing approaches the DEWI HLA also reuses some features from other standardized technologies and architectures. The HLA will allow networks with different industrial sensor technologies to exchange information between them or with external clients via standard interfaces, thus providing a consolidated access to sensor information of different domains. This is an important aspect for smart city applications, Big Data and internet-of-things (IoT).

2016Journal article

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The DEWI High-Level Architecture: Wireless Sensor Networks in Industrial Applications

Publication . Robles, Ramiro; Rom, Werner; Tovar, Eduardo

This paper presents the high-level architecture (HLA) of the research project DEWI (dependable embedded wireless infrastructure). The objective of this HLA is to serve as a reference for the development of industrial wireless sensor and actuator networks (WSANs) based on the concept of the DEWI Bubble. The DEWI Bubble is defined here as a high-level abstraction of an industrial WSAN with enhanced interoperability (via standardized interfaces), technology reuse, and cross-domain development. This paper details the design criteria used to define the HLA and the organization of the infrastructure inside and outside the DEWI Bubble. The description includes the different perspectives, models or views of the architecture: the entity model, the layered model, and the functional view model (including an overview of interfaces). The HLA constitutes an extension of the ISO/IEC SNRA (sensor network reference architecture) towards the support of industrial applications. To improve interoperability with existing approaches the DEWI HLA also reuses some features from other standardized technologies and architectures. The HLA will allow networks with different industrial sensor technologies to exchange information between them or with external clients via standard interfaces, thus providing a consolidated access to sensor information of different domains. This is an important aspect for smart city applications, big data and internet-of-things (IoT).

2016Conference object

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Performance Analysis of MRC Receivers with Adaptive Modulation and Coding in Rayleigh Fading Correlated Channels with Imperfect CSIT

Publication . Robles, Ramiro; Lavendelis, Egons; Tovar, Eduardo

This paper addresses the performance analysis of an adaptive wireless link with one antenna transmitter and a multiple antenna maximum-ratio combining (MRC) receiver. Two main assumptions are used in this paper: (1) Rayleigh fading correlated channels (i.e., MRC branch correlation) and (2) imperfect (outdated) channel state information at the transmitter (CSIT) side. he main contribution of this work lies in the derivation of analytic expressions (in terms of a series expansion) of the statistics of correct packet reception conditional on the decisions made by the transmitter based on outdated CSIT. he novelty of this derivation is the joint modelling of spatially correlated branches, imperfect CSIT, and adaptive modulation based on threshold-trigger decision. Contrary to common belief, the results presented here suggest that spatial correlation not always afects the performance of the MRC receiver: at low signal-to-noise ratio (SNR), correlation can improve performance rather than degrading it. In contrast, at high SNR, correlation is found to always degrade performance. At high SNR, correlation tends to worse the degrading efects of imperfect CSIT, particularly when the number of antennas increases. Imperfect CSIT causes errors in the assignment of MCSs, thus reducing throughput performance. hese errors become more evident in the high SNR regime, particularly when the values of branch correlation and the number of antennas increase.

2017Journal article

Open access

Extending T-Res with mobility for context-aware IoT

Publication . Gaur, Shashank; Rangarajan, Raghuraman; Tovar, Eduardo

In this paper, we develop a framework for building context-aware applications in IoT. The IoT paradigm brings in various new issues such as macroprogramming, interoperability for heterogeneous devices and in-network processing. Solutions to these issues can enable IoT to support all available resources in an efficient manner and also enable ease of access for users. In addition, this can help in collecting useful information about the user and the system, such as context. Understanding context of different entities and taking actions accordingly will enable a context-aware IoT. However, no complete solution is available to this issue of achieving context-awareness in IoT. In this paper, as a step towards a context-aware framework, we present a mobilityenabling extension of the T-Res programming abstraction. We implement a web-based framework for users to write contextaware applications. We then describe and implement an automated mechanism for deploying these applications.

2016Conference object

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Network Diversity Multiple Access with Imperfect Channel State Information at the Transmitter Side

Publication . Samano-Robles, Ramiro

Network diversity multiple access (NDMA) is the family of algorithms with the highest potential throughput in the literature of signal-processing assisted random access protocols. NDMA uses the concept of protocol-induced retransmissions to create an adaptive source of diversity. This diversity is used to resolve packet collisions employing signal separation tools without the explicit need (or as a complement) of a multiple antenna receiver. This paper proposes a further improvement on the performance of NDMA by allowing each terminal access to an outdated copy of its individual channel state information (CSI). Based on this decentralized CSI, each terminal conveniently decides to transmit only if the estimated channel gain surpasses a threshold that is optimized to maximize performance. This ensures that the probability of terminal presence detection, and thus the probability of correct estimation of the collision multiplicity are considerably improved at the receiver end. The paper is focused on the modelling of the receiver operational characteristic (ROC) of the terminal presence detector considering that the CSI used by each terminal is potentially inaccurate (outdated) due to feedback delay. The results indicate that when the correlation coefficient that describes the accuracy of the available CSI tends to zero, the scheme degrades into the conventional NDMA. By contrast, when the quality of the channel state information improves, the throughput can nearly achieve the nominal channel rate (minimum throughput penalty). The selection of the detector thresholds for channel gain and terminal presence is optimized to maximize system performance.

2016Conference object

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