| 1. |
|
|
| 2. |
- Agrawal, Piyush, et al.
(författare)
-
Long Term Channel Characterization for Energy Efficient Transmission in Industrial Environments
- 2014
-
Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 62:8, s. 3004-3014
-
Tidskriftsartikel (refereegranskat)abstract
- One of the challenges for a successful use of wireless sensor networks in process industries is to design networks with energy efficient transmission, to increase the lifetime of the deployed network while maintaining the required latency and bit-error rate. The design of such transmission schemes depend on the radio channel characteristics of the region. This paper presents an investigation of the statistical properties of the radio channel in a typical process industry, particularly when the network is meant to be deployed for a long time duration, e. g., days, weeks, and even months. Using 17-20-h-long extensive measurement campaigns in a rolling mill and a paper mill, we highlight the non-stationarity in the environment and quantify the ability of various distributions, given in the literature, to describe the variations on the links. Finally, we analyze the design of an optimal received signal-to-noise ratio (SNR) for the deployed nodes and show that improper selection of the distribution for modeling of the variations in the channel can lead to an overuse of energy by a factor of four or even higher.
|
|
| 3. |
- Barac, Filip, 1983-, et al.
(författare)
-
A Lightweight Routing Protocol for Industrial Wireless Sensor and Actuator Networks
- 2011
-
Ingår i: Proceedings of IECON 2011 - 37th Annual Conference on IEEE Industrial Electronics Society. - Melbourne, Australia : IEEE Industrial Electronics Society. - 9781612849720 ; , s. 2980-2985
-
Konferensbidrag (refereegranskat)abstract
- The applications of Industrial Wireless Sensor and Actuator Networks (IWSAN) are time-critical and subject to strict requirements in terms of end-to-end delay and reliability of data delivery. A notable shortcoming of the existing wireless industrial communication standards is the existence of overcomplicated routing protocols, whose adequacy for the intended applications is questionable [1]. This paper evaluates the potentials of flooding as a data dissemination technique in IWSANs. The concept of flooding is recycled by introducing minimal modifications to its generic form and compared with a number of existing WSN protocols, in a variety of scenarios. The simulation results of all scenarios observed show that our lightweight approach is able to meet stringent performance requirements for networks of considerable sizes. Furthermore, it is shown that this solution significantly outperforms a number of conventional WSN routing protocols in all categories of interest.
|
|
| 4. |
- Barac, Filip, et al.
(författare)
-
Channel Coding and Interleaving in Industrial WSN : Abiding to Timing Constraints and Bit Error Nature
- 2013
-
Ingår i: Proceedings - M and N 2013: 2013 IEEE International Workshop on Measurements and Networking. - 9781467328739 ; , s. 46-51
-
Konferensbidrag (refereegranskat)abstract
- Forward Error Correction is a preemptive manner of improving communication reliability. Albeit not a part of IEEE 802.15.4-2006 standard, its application in Industrial Wireless Sensor Networks has been widely considered. Nevertheless, this study is the first performance analysis on real error traces with sufficiently lightweight channel codes, with respect to IEEE 802.15.4-2006 and industrial wireless communication timing constraints. Based on these constraints and bit error properties from the collected traces, the use of Reed-Solomon (15,7) block code is suggested, which can be implemented in software. Experiments show that bit error nature on links affected by multipath fading and attenuation in industrial environments is such that RS(15,7) can correct ≥95% of erroneously received packets, without the necessity for interleaving. On links under IEEE 802.11 interference, typically up to 50% of corrupted packets can be recovered by combining RS(15,7) with symbol interleaving, which has proven to be more effective than its bit counterpart. The optimal interleaving depth is found empirically and it is shown that simple bit-interleaved 1/3 repetition code achieves at least 90% of correcting performance of RS(15,7) code on uninterfered links that operate ≥10 dB above the sensitivity threshold.
|
|
| 5. |
- Barac, Filip, 1983-, et al.
(författare)
-
Channel Diagnostics for Wireless Sensor Networks in Harsh Industrial Environments
- 2014
-
Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:11, s. 3983-3995
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 6. |
- Barac, Filip, et al.
(författare)
-
LPED: Channel Diagnostics in WSN Through Channel Coding and Symbol Error Statistics
- 2014
-
Ingår i: IEEE ISSNIP 2014 - 2014 IEEE 9th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, Conference Proceedings. - Singapore : IEEE Sensors Council. - 9781479928422 ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 7. |
- Barac, Filip, et al.
(författare)
-
Scrutinizing Bit- and Symbol-Errors of IEEE 802.15.4 Communication in Industrial Environments
- 2014
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 63:7, s. 1783-1794
-
Tidskriftsartikel (refereegranskat)abstract
- The knowledge of error nature in wireless channels is an essential constituent of efficient communication protocol design. To this end, this paper is the first comprehensive bit- and symbol-level analysis of IEEE 802.15.4 transmission errors in industrial environments. The intention with this paper is to extract the error properties relevant for future improvements of wireless communication reliability and coexistence of radio systems in these harsh conditions. An extensive set of bit-error traces was collected in a variety of scenarios and industrial environments, showing that error behavior is highly dependent on the cause of packet corruption. It is shown that errors inflicted by multipath fading and attenuation exhibit different properties than those imposed by IEEE 802.11 interference. The statistical behavior of these two patterns is concurrently investigated in terms of differences in bit-error distribution, error burst length, channel memory length, and the scale of packet corruption. With these conclusions at hand, abiding to the computational constraints of embedded sensors and the statistical properties of bit-errors, a Reed-Solomon $(15,k)$ block code is chosen to investigate the implications of bit-error nature on practical aspects of channel coding and interleaving. This paper is concluded by a number of findings of high practical relevance, concerning the optimal type, depth, and meaningfulness of interleaving.
|
|
| 8. |
- Barac, Filip, et al.
(författare)
-
Towards Reliable and Lightweight Communication in Industrial Wireless Sensor Networks
- 2012
-
Ingår i: Procedings of the IEEE 10th International Conference on Industrial Informatics, INDIN 2012. - Beijing, China : IEEE conference proceedings. - 9781467303118 ; , s. 1218-1224
-
Konferensbidrag (refereegranskat)abstract
- In this paper we address the issues of timeliness and transmission reliability of existing industrial communication standards. We combine a Forward Error Correction coding schemeon the Medium Access Control layer with a lightweight routing protocol to form an IEEE 802.15.4-conformable solution, whichcan be implemented into already existing hardware without violating the standard. After laying the theoretical foundations,we conduct a performance evaluation of the proposed solution.The results show a substantial gain in reliability and reducedlatency, compared to the uncoded transmissions, as well ascommon Wireless Sensor Network routing protocols.
|
|
| 9. |
- Dobslaw, Felix, 1983-, et al.
(författare)
-
QoS Assessment for Mission-critical Wireless Sensor Network Applications
- 2013
-
Ingår i: Proceedings - Conference on Local Computer Networks, LCN. - : IEEE Xplore. ; , s. 663-666
-
Konferensbidrag (refereegranskat)abstract
- Wireless sensor networks (WSN) must ensure worst-case end-to-end delay and reliability guarantees for mission-critical applications.TDMA-based scheduling offers delay guarantees, thus it is used in industrial monitoring and automation. We propose to evolve pairs of TDMA schedule and routing-tree in a cross-layer in order to fulfill multiple conflicting QoS requirements,exemplified by latency and reliability.The genetic algorithm we utilize can be used as an analytical tool for both the feasibility and expected QoS in production. Near-optimal cross-layer solutions are found within seconds and can be directly enforced into the network.
|
|
| 10. |
- Dong, X., et al.
(författare)
-
Impact of Doppler spread and adaptive modulation on TCP throughput in Rayleigh fading channels
- 2010
-
Ingår i: AEU - International Journal of Electronics and Communications. - : Elsevier BV. - 1434-8411 .- 1618-0399. ; 64:11, s. 1082-1089
-
Tidskriftsartikel (refereegranskat)abstract
- A number of wireless systems have recently adopted adaptive modulation (AM) schemes to improve its efficiency. In this letter, our aim is to study the impact Doppler spread and adaptive modulation has on transmission control protocol (TCP) throughput in Rayleigh fading channels. We consider a finite state Markov channel (FSMC) model, which is a useful model for analyzing radio channel with nonindependent fading. Furthermore, we use a Markov model for TCP evolution and evaluate the TCP performance by computer simulations. In our simulations we have compared the TCP Reno scheme with TCP Tahoe scheme. The results indicate that a large Doppler spread leads to lower TCP throughput due to more frequent transitions of channel states and modulation schemes which make it difficult for the TCP congestion control mechanism to accommodate the dynamic link characteristics.
|
|
