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Barac, Filip
Publications (10 of 17) Show all publications
Grimaldi, S., Gidlund, M., Lennvall, T. & Barac, F. (2016). Detecting Communication Blackout in Industrial Wireless Sensor Networks. In: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS: . Paper presented at 12th IEEE World Conference on Factory Communication Systems, WFCS 2016; Aveiro; Portugal; 3 May 2016 through 6 May 2016; Category numberCFP16WFC-ART; Code 122676. , Article ID 7496502.
Open this publication in new window or tab >>Detecting Communication Blackout in Industrial Wireless Sensor Networks
2016 (English)In: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, 2016, article id 7496502Conference paper, Published paper (Refereed)
Abstract [en]

Communication blackout is one of the most serious pitfalls of Wireless Sensor Networks (WSN) in industrial automation context. The industrial radio channel exhibits pronounced effects of multipath fading and wireless LAN (WLAN) interference that can potentially lead to temporary communication failures, as well as complete isolation of network devices. The current IWSN standards adopt known countermeasures to cope with the harshness of the radio channel, but they lack solutions specifically oriented to detect blackouts and self-recover the communication fulfilling hard deadline constraints. In this work we focus onthe problem of blackout detection with specific interest for the WirelessHART standard, introducing a Blackout Detection Service (BDS) expressly addressed to multi-hop periodic communicationwith sensors and actuators. The BDS monitors end-to-end acknowledgement messages and builds specific metrics to promptly identify communication outages, enabling three criticality classes. The algorithm is tested in the ns-2 network simulator and results show that the proposed system is able to detect blackout events with reaction delays of the order of 4-5 times the refresh rate of nodes and to discriminate between smalland temporary network issues and serious blackout scenarios, opening the field for recovery strategies.

Keywords
WSN, reliability, real-time, networks
National Category
Computer Engineering
Identifiers
urn:nbn:se:miun:diva-27752 (URN)10.1109/WFCS.2016.7496502 (DOI)000382857300008 ()2-s2.0-84982833586 (Scopus ID)STC (Local ID)978-1-5090-2339-4 (ISBN)STC (Archive number)STC (OAI)
Conference
12th IEEE World Conference on Factory Communication Systems, WFCS 2016; Aveiro; Portugal; 3 May 2016 through 6 May 2016; Category numberCFP16WFC-ART; Code 122676
Projects
ASIS
Funder
Knowledge Foundation
Available from: 2016-05-23 Created: 2016-05-23 Last updated: 2018-01-10Bibliographically approved
Barac, F. (2016). Error mitigation in industrial wireless sensor networks: Corrupted packet forensics and recovery. (Doctoral dissertation). Sundsvall: Mittuniversitetet
Open this publication in new window or tab >>Error mitigation in industrial wireless sensor networks: Corrupted packet forensics and recovery
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wireless sensor networks (WSN) are gradually penetrating the industrial automation domain. This process is, however, inhibited by a number of challenges that need to be considered and addressed before WSN can serve the most demanding industrial applications. In the context of process automation, existing technology can only serve the three least critical application classes related to non-critical monitoring of slowly-changing physical variables. The main issue in that respect is the insufficient communication timeliness and reliability, caused by the influence of harsh radio environment and the infeasibility of applying advanced communication techniques, due to the poor computational power of low-cost specialized hardware. The goal of this work is to improve wireless communication reliability in industrial environments, where the proposed solutions are generally applicable to other WSN domains as well as radio environments. This research is based on the notion that corrupt packets contain valuable channel state information that can be leveraged to improve communication robustness. The research methodology used in this work is rather unconventional, compared to existing research, but also highly intuitive, bearing in mind that counteracting a phenomenon requires a thorough knowledge of its properties. In order to rectify the aforementioned challenges, this work makes the following three contributions. The first contribution is a comprehensive analysis of communication errors recorded in practically relevant scenarios in a number of industrial environments. The related literature is seemingly rich, but essentially poor, due to inadequate measurement objectives, environments, and scenarios. The main research outcome of this measurement campaign is a set of practically relevant conclusions, which can be used for the design of coding, interleaving and packet recovery schemes. The second contribution is the design of two packet recovery schemes, based on the knowledge about error patterns obtained in the industrial measurement campaign. The first scheme is a proposal for redefinition of the IEEE 802.15.4 physical layer, where digital errors are counteracted at the earliest stage in the receiver chain. The second scheme exploits the determinism in packet structure inherent to industrial communication. Both schemes significantly improve the correctability of corrupted packets received. The third contribution is a channel diagnostics algorithm that determines whether a packet was corrupt by multipath fading and attenuation or by wireless local area network interference. The algorithm is derived from the error traces collected in three industrial environments and tested at a fourth, previously unused, industrial site. The results of live tests verify the ability of the proposed algorithm to promptly reestablish communication after a sudden deterioration of channel quality.

Place, publisher, year, edition, pages
Sundsvall: Mittuniversitetet, 2016. p. 158
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 239
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:miun:diva-28759 (URN)STC (Local ID)978-91-88025-54-8 (ISBN)STC (Archive number)STC (OAI)
Public defence
2016-03-02, Sundsvall, 10:15 (English)
Opponent
Supervisors
Available from: 2016-09-12 Created: 2016-09-12 Last updated: 2018-01-10Bibliographically approved
Lavassani, M., Barac, F., Gidlund, M. & Zhang, T. (2016). Handling Event-Triggered Traffic of Safety and Closed-Loop Control Systems in WSANs. In: 14th IEEE International Conference on Industrial Informatics (INDIN'16): . Paper presented at 14th IEEE International Conference on Industrial Informatics (INDIN'16), Poitiers, France, July 18-21, 2016 (pp. 631-636). IEEE, Article ID 7819237.
Open this publication in new window or tab >>Handling Event-Triggered Traffic of Safety and Closed-Loop Control Systems in WSANs
2016 (English)In: 14th IEEE International Conference on Industrial Informatics (INDIN'16), IEEE, 2016, p. 631-636, article id 7819237Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
IEEE, 2016
Keywords
WSN, QoS, Scheduling
National Category
Communication Systems
Identifiers
urn:nbn:se:miun:diva-28557 (URN)10.1109/INDIN.2016.7819237 (DOI)000393551200096 ()2-s2.0-85012891393 (Scopus ID)STC (Local ID)978-150-902-870-2 (ISBN)STC (Archive number)STC (OAI)
Conference
14th IEEE International Conference on Industrial Informatics (INDIN'16), Poitiers, France, July 18-21, 2016
Projects
TIMELINESS
Funder
Knowledge Foundation
Available from: 2016-08-18 Created: 2016-08-18 Last updated: 2017-06-30Bibliographically approved
Barac, F., Gidlund, M. & Zhang, T. (2015). CLAP: Chip-Level Augmentation of IEEE 802.15.4 PHY for Error-Intolerant WSN Communication. In: IEEE Vehicular Technology Conference: . Paper presented at 81st IEEE Vehicular Technology Conference, VTC Spring 2015; Glasgow; United Kingdom; 11 May 2015 through 14 May 2015 (pp. 1-7). Glasgow, Scotland: IEEE Vehicular Technology Society
Open this publication in new window or tab >>CLAP: Chip-Level Augmentation of IEEE 802.15.4 PHY for Error-Intolerant WSN Communication
2015 (English)In: IEEE Vehicular Technology Conference, Glasgow, Scotland: IEEE Vehicular Technology Society , 2015, p. 1-7Conference paper, Published paper (Refereed)
Abstract [en]

Communication reliability is the ultimate priority in safety-critical wireless sensor network (WSN) communication. Surprisingly enough, the enormous potential of error control on direct sequence spread spectrum (DSSS) chips in IEEE 802.15.4 has been completely overlooked by the WSN community, possibly due to incorrect presumptions, such as the concerns about computational overhead. Current error-correction schemes in WSN counteract the error process once the errors have already propagated to bit- and packet-level. Motivated by the notion that errors should be confronted at the earliest stage, this work presents CLAP, a novel method that tremendously improves the error correction in WSN by fortifying the IEEE 802.15.4 Physical layer (PHY) with straightforward manipulations of DSSS chips. CLAP is implemented on a software-defined radio platform, and evaluated on real error traces from heavily WLAN-interfered IEEE 802.15.4 transmissions at 3 different environments. CLAP boosts the number of corrected packets by 1.78-6.88 times on severely interfered links, compared to two other state-of-the-art schemes. The overhead in terms of computational complexity is about 10% of execution time of the OQPSK demodulator in the legacy IEEE 802.15.4 receiver chain.

Place, publisher, year, edition, pages
Glasgow, Scotland: IEEE Vehicular Technology Society, 2015
Keywords
Chip error correction, IEEE 802.15.4, WSN
National Category
Telecommunications
Identifiers
urn:nbn:se:miun:diva-24838 (URN)10.1109/VTCSpring.2015.7145742 (DOI)000371404700157 ()2-s2.0-84940398673 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Conference
81st IEEE Vehicular Technology Conference, VTC Spring 2015; Glasgow; United Kingdom; 11 May 2015 through 14 May 2015
Available from: 2015-04-16 Created: 2015-04-16 Last updated: 2016-12-23Bibliographically approved
Barac, F., Gidlund, M. & Zhang, T. (2015). PREED: Packet Recovery by Exploiting the Determinism in Industrial WSN Communication. In: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2015: . Paper presented at 11th IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2015; Fortaleza; Brazil; 10 June 2015 through 12 June 2015; Category numberE5507; Code 115690 (pp. 81-90). Fortaleza, Brazil: IEEE Computer Society
Open this publication in new window or tab >>PREED: Packet Recovery by Exploiting the Determinism in Industrial WSN Communication
2015 (English)In: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2015, Fortaleza, Brazil: IEEE Computer Society, 2015, p. 81-90Conference paper, Published paper (Refereed)
Abstract [en]

The requirements of safety-critical wireless sensornetwork (WSN) applications, such as closed-loop control andtraffic safety, cannot be met by the IEEE 802.15.4-2006 standardnor its industrial WSN (IWSN) derivatives. The main problem inthat respect is the communication reliability, which is seriouslycompromised by 2.4-GHz interference, as well as multipathfading and attenuation (MFA) at industrial facilities. Meanwhile,communication blackouts in critical WSN applications maylead to devastating consequences, including production halts,damage to production assets and can pose a threat to safetyof human personnel. This work presents PREED, a method toimprove the reliability by exploiting the determinism in IWSNcommunication. The proposed solution is based on the analysisof bit error traces collected in real transmissions at four differentindustrial environments. A case study on WirelessHART packetformat shows that PREED recovers 42%-134% more packetsthan the competing approaches on links compromised by WLANinterference. In addition, PREED reduces one of the most trivialcauses of packet loss in IWSN, i.e. the corruption offrame lengthbyte, by 88% and 99%, for links exposed to WLAN interferenceand MFA, respectively.

Place, publisher, year, edition, pages
Fortaleza, Brazil: IEEE Computer Society, 2015
Keywords
Error mitigation, FEC, IEEE 802.15.4, Interleaving, IWSN, Packet recovery, Wireless HART
National Category
Telecommunications
Identifiers
urn:nbn:se:miun:diva-26129 (URN)10.1109/DCOSS.2015.8 (DOI)000380515100009 ()2-s2.0-84945904727 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Conference
11th IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2015; Fortaleza; Brazil; 10 June 2015 through 12 June 2015; Category numberE5507; Code 115690
Note

INSPEC Accession Number: 15310425

Available from: 2015-10-22 Created: 2015-10-22 Last updated: 2016-12-23Bibliographically approved
Sisinni, E., Caiola, S., Flammini, A., Gidlund, M. & Barac, F. (2015). Simple interference detection and classification for industrial Wireless Sensor Networks. In: Conference Record - IEEE Instrumentation and Measurement Technology Conference: . Paper presented at 2015 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2015, 11 May 2015 through 14 May 2015 (pp. 2106-2110). Pisa, Italy: IEEE
Open this publication in new window or tab >>Simple interference detection and classification for industrial Wireless Sensor Networks
Show others...
2015 (English)In: Conference Record - IEEE Instrumentation and Measurement Technology Conference, Pisa, Italy: IEEE, 2015, p. 2106-2110Conference paper, Published paper (Refereed)
Abstract [en]

Wireless Sensor Networks (WSNs) are increasingly deployed in office blocks, residential areas and also industrial locations, thanks to advantages in terms of flexibility and scalability. Nowadays available wireless fieldbuses are widely adopted for process monitoring and offer performance comparable with the wired counterparts, despite they still are more sensitive to interference from external sources. This work investigates the main sources of interference in the 2.4 GHz ISMband and evaluates the adoption of a simple algorithm to identify the interference. The proposed technique, called LPED, is based on bit error nature and forward error correction. The required computational effort is compatible with resources normally available in WSN nodes, as experimentally verified. In addition, performance in presence of IEEE802.11 and iWLAN is also verified; classification is correct in about 90% of cases.

Place, publisher, year, edition, pages
Pisa, Italy: IEEE, 2015
Keywords
Interference detection, Smart devices, Smart sensing, Wireless sensor networks
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-25922 (URN)10.1109/I2MTC.2015.7151608 (DOI)000380587900365 ()2-s2.0-84938828876 (Scopus ID)STC (Local ID)9781479961139 (ISBN)STC (Archive number)STC (OAI)
Conference
2015 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2015, 11 May 2015 through 14 May 2015
Note

CODEN: CRIIE

Available from: 2015-09-23 Created: 2015-09-23 Last updated: 2016-12-23Bibliographically approved
Barac, F., Gidlund, M. & Zhang, T. (2015). Ubiquitous, yet Deceptive: Hardware-Based Channel Metrics on Interfered WSN Links. IEEE Transactions on Vehicular Technology, 64(5), 1766-1778
Open this publication in new window or tab >>Ubiquitous, yet Deceptive: Hardware-Based Channel Metrics on Interfered WSN Links
2015 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 5, p. 1766-1778Article in journal (Refereed) Published
Abstract [en]

The ease of acquiring hardware-based link quality indicators is an alluring property for fast channel estimation in time- and safety-critical Wireless Sensor Network (WSN) applications, such as closed-loop control and interlocking. The two rudimentary hardware-based channel quality metrics, Received Signal Strength (RSS) and Link Quality Indicator (LQI), are the key constituents of channel estimation and a plethora of other WSN functionalities, from routing to transmit power control. Nevertheless, this study highlights three deficient aspects of these two indicators: 1) overall deceptiveness, i.e. the inability to reveal the presence of interference, falsely indicating excellent channel conditions in an unacceptably high fraction of cases; 2) the burstiness of missed detections, which compromises the attempts to eliminate the deceptiveness by averaging; 3) high mutual discrepancy of the two indicators, observed in 39-73% of packets, throughout different scenarios. The ability of RSS and LQI to indicate IEEE 802.11 interference is scrutinized in a variety of scenarios in typical industrial environments, using commercialoff- the-shelf hardware and realistic network topologies, giving the findings of this study a high general validity and practical relevance.

Keywords
IEEE 802.15.4, industrial wireless sensor network (WSN), interference, link quality, link quality indicator (LQI), received signal strength (RSS)
National Category
Telecommunications
Identifiers
urn:nbn:se:miun:diva-22908 (URN)10.1109/TVT.2014.2334494 (DOI)000354472800010 ()2-s2.0-84929340066 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Projects
COINS
Funder
Knowledge Foundation
Note

Publ online Jul 2014

Available from: 2014-09-11 Created: 2014-09-11 Last updated: 2017-12-05Bibliographically approved
Barac, F., Caiola, S., Gidlund, M., Sisinni, E. & Zhang, T. (2014). Channel Diagnostics for Wireless Sensor Networks in Harsh Industrial Environments. IEEE Sensors Journal, 14(11), 3983-3995
Open this publication in new window or tab >>Channel Diagnostics for Wireless Sensor Networks in Harsh Industrial Environments
Show others...
2014 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 14, no 11, p. 3983-3995Article in journal (Refereed) Published
Abstract [en]

Wireless sensor network communication in industrial environments is compromised by interference, multipath fading, and signal attenuation. In that respect, accurate channel diagnostics is imperative to selecting the adequate countermeasures. This paper presents the lightweight packet error discriminator (LPED) that infers the wireless link condition by distinguishing between errors caused by multipath fading and attenuation, and those inflicted by interfering wideband single-channel communication systems (e.g., IEEE 802.11b/g), based on the differences in their error footprints. The LPED uses forward error correction in a novel context, namely, to determine the symbol error density, which is then fed to a discriminator for error source classification. The classification criteria are derived from an extensive set of error traces collected in three different types of industrial environments, and verified on a newly collected set of error traces. The proposed solution is evaluated both offline and online, in terms of classification accuracy, speed of channel diagnostics, and execution time. The results show that in ≥91% of cases, a single packet is sufficient for a correct channel diagnosis, accelerating link state inference by at least 270%, compared with the relevant state-of-the-art approaches. The execution time of LPED, for the worst case of packet corruption and maximum packet size, is below 30 ms with ≤3% of device memory consumption. Finally, live tests in an industrial environment show that LPED quickly recovers from link outage, by losing up to two packets on average, which is only one packet above the theoretical minimum.

Keywords
IWSN, interference recognition, error discrimination, FEC, bit error traces
National Category
Telecommunications
Identifiers
urn:nbn:se:miun:diva-22909 (URN)10.1109/JSEN.2014.2356972 (DOI)000343610500001 ()2-s2.0-84923182066 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Projects
COINS
Funder
Knowledge Foundation
Available from: 2014-09-11 Created: 2014-09-11 Last updated: 2017-12-05Bibliographically approved
Barac, F., Gidlund, M. & Zhang, T. (2014). LPED: Channel Diagnostics in WSN Through Channel Coding and Symbol Error Statistics. In: IEEE ISSNIP 2014 - 2014 IEEE 9th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, Conference Proceedings: . Paper presented at 9th IEEE International Conference on Intelligent Sensors, Sensor Networks and Information Processing, IEEE ISSNIP 2014; Singapore; Singapore; 21 April 2014 through 24 April 2014; Category numberCFP14842-ART; Code 106024 (pp. 1-6). Singapore: IEEE Sensors Council
Open this publication in new window or tab >>LPED: Channel Diagnostics in WSN Through Channel Coding and Symbol Error Statistics
2014 (English)In: IEEE ISSNIP 2014 - 2014 IEEE 9th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, Conference Proceedings, Singapore: IEEE Sensors Council, 2014, p. 1-6Conference paper, Published paper (Refereed)
Abstract [en]

Three major obstacles to wireless communication are electromagnetic interference, multipath fading and signal attenuation. The former stems mainly from collocated wireless systems operating in the same frequency band, while the latter two originate from physical properties of the environment. Identifying the source of packet corruption and loss is crucial, since the adequate countermeasures for different types of threats are essentially different. This problem is especially pronounced in industrial monitoring and control applications, where IEEE 802.15.4 communication is expected to deliver data within tight deadlines, with minimal packet loss. This work presents the Lightweight Packet Error Discriminator (LPED) that distinguishes between errors caused by multipath fading and attenuation, and those inflicted by IEEE 802.11 interference. LPED uses Forward Error Correction to determine the symbol error positions inside erroneously received packets and calculates the error density, which is then fed to a discriminator for error source classification. The statistical constituents of LPED are obtained from an extensive measurement campaign in two different types of industrial environments. The classifier incurs no overhead and in ≥90% of cases a single packet is sufficient for a correct channel diagnosis. Experiments show that LPED accelerates link diagnostics by at least 190%, compared to the relevant state-of-the-art approaches.

Place, publisher, year, edition, pages
Singapore: IEEE Sensors Council, 2014
National Category
Communication Systems
Identifiers
urn:nbn:se:miun:diva-21423 (URN)10.1109/ISSNIP.2014.6827630 (DOI)000356411200044 ()2-s2.0-84903744137 (Scopus ID)STC (Local ID)978-1-4799-2842-2 (ISBN)STC (Archive number)STC (OAI)
Conference
9th IEEE International Conference on Intelligent Sensors, Sensor Networks and Information Processing, IEEE ISSNIP 2014; Singapore; Singapore; 21 April 2014 through 24 April 2014; Category numberCFP14842-ART; Code 106024
Funder
Knowledge Foundation
Available from: 2014-02-25 Created: 2014-02-25 Last updated: 2017-03-06Bibliographically approved
Shen, W., Zhang, T., Barac, F. & Gidlund, M. (2014). PriorityMAC: A Priority-Enhanced MAC Protocol for Critical Traffic in Industrial Wireless Sensor and Actuator Networks. IEEE Transactions on Industrial Informatics, 10(1), 824-835
Open this publication in new window or tab >>PriorityMAC: A Priority-Enhanced MAC Protocol for Critical Traffic in Industrial Wireless Sensor and Actuator Networks
2014 (English)In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 10, no 1, p. 824-835Article in journal (Refereed) Published
Abstract [en]

This paper proposes PriorityMAC, a priority-enhanced medium access control protocol, designed for critical traffic in industrial wireless sensor and actuator networks (IWSAN). A notable trend in industrial automation in recent years has been the replacement of wired communication by IWSANs. Exceeding the required delay bound for unpredictable and emergency traffic could lead to system instability, economic and material losses, system failure, and, ultimately, a threat to human safety. Guaranteeing the timely delivery of the IWSAN critical traffic and its prioritization over regular traffic (e.g., noncritical monitoring traffic) is a significant challenge. Therefore, we present the design, implementation, performance analysis, and evaluation of PriorityMAC. A series of novel mechanisms (e.g., high priority indication space) are proposed to enable high-priority traffic to hijack the transmission bandwidth of the low-priority traffic. To the best of our knowledge, this is the first priority-enhanced MAC protocol compatible with industrial standards for IWSAN. PriorityMAC is implemented in TinyOS and evaluated on a testbed of Telosb motes. The experimental results indicate that PriorityMAC efficiently handles different traffic categories with different latency requirements, thereby achieving a significant improvement in the delivery latency compared with the current industrial standards. © 2005-2012 IEEE.

Keywords
industrial wireless sensor and actuator networks (IWSANs), ISA100.11a, MAC protocols, priority, WirelessHART
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-21050 (URN)10.1109/TII.2013.2280081 (DOI)000336668600082 ()2-s2.0-84891065883 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Note

Art. No.: 6587846

Available from: 2014-01-14 Created: 2014-01-14 Last updated: 2017-12-06Bibliographically approved
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