Master thesis topics

Professor Sandis Spolitis

Evaluation of Minimum Channel Interval for NRZ-OOK, RZ-OOK, and Duobinary Transmission Systems

Brief description: The thesis will focus on the evaluation of minimal channel interval for wavelength-division multiplexed (WDM) fiber optical communication systems. Minimal channel interval (GHz), usually is based on ITU-T G.694.1 recommendation (100, 50, 25, 12.5, 6.25 GHz, etc.) at fixed transmission distance. The thesis can focus on the investigation of communication system performance with different transmission speeds (2.5, 10, or 40 Gbit/s per channel) with a various number of channels (e.g. 8, 16, 32). Additionally, or instead of minimal channel interval, the thesis can focus on the implementation of dispersion compensation methods (DCF, FBG) that can be used to minimize chromatic dispersion (CD) induced signal degradation (e.g. intersymbol interference (ISI)) and extend the operation distance/signal quality of fiber optical communication system.  

Tools used: Synopsys OptSim (modelling and simulations of fiber optical communication system), MATLAB (for data representation, analysis) 

Additional literature: 

  • ITU-T Recommendation G.694.1, “Transmission media and optical systems characteristics – characteristics of optical system. Spectral grids for WDM applications: DWDM frequency grid,” November 2020. 
  • Salgals, T., Supe, A., Bobrovs, V., Porins, J., Spolitis, S. “Comparison of dispersion compensation techniques for real-time up to 160 Gbit/s DWDM C-band transmission”, (2020) Elektronika ir Elektrotechnika, 26 (2), pp. 85-93. 
  • Spolitis, I. Kurbatska and V. Bobrovs, “Considering of PAM-4, DB, NRZ and RZ for Implementation in Next-Generation PONs,” 2018 26th International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2018, pp. 1-6, doi: 10.23919/SOFTCOM.2018.8555736. 
  • Udalcovs and V. Bobrovs, “Investigation of spectrally efficient transmission for differently modulated optical signals in mixed data rates WDM systems,” 2011 IEEE Swedish Communication Technologies Workshop (Swe-CTW), 2011, pp. 7-12, doi: 10.1109/Swe-CTW.2011.6082493. 
  • Aleksejeva and S. Spolitis, “Performance investigation of dispersion compensation methods for WDM-PON transmission systems,” 2017 Progress In Electromagnetics Research Symposium – Spring (PIERS), 2017, pp. 2437-2442, doi: 10.1109/PIERS.2017.8262160. 

Four-Wave-Mixing Based Optical Frequency Comb Source for Optical Communications

Brief description: Four-wave-mixing (FWM) is one of the well-known nonlinear optical effects (NOE) that affect the operation quality of fiber optical communication lines. However, it is known that this nonlinear optical effect can be used productively in fiber optical communication systems for various applications, e.g. as an optical frequency comb source (OFC) or light source, capable to replace several independent laser sources. In this thesis, the student will build a wavelength division multiplexed (WDM) fiber optical communication system (possible modulation formats: NRZ-OOK, RZ-OOK, Duobinary, bitrates: 2.5, 10 Gbit/s) and demonstrate how the FWM-based comb source can be used in such a system for data transmission. The performance of sucha light source will be investigated in the terms of overall data transmission system performance (operation distance, BER, Q-factor, etc.). A WDM system with a various number of channels can be investigated as well (e.g. 8, 16, 32). 

Tools used: Synopsys OptSim (modeling and simulations of fiber optical communication system), MATLAB (for data representation, analysis) 

Additional literature: 

  • Vilcane, K., S. Matsenko, M. Parfjonovs, R. Murnieks, M. Aleksejeva, and S. Spolitis, “Implementation of multi-wavelength source for DWDM-PON fiber optical transmission systems,” Latvian Journal of Physics and Technical Sciences, Vol. 57, No. 4, 24-33, 2020. 
  • Lyashuk, I., A. Shchemelev, and G. Ivanov, “A hybrid TDM/WDM-pon system with FWM-generated source of multiwavelength optical signals,” Latvian Journal of Physics and Technical Sciences, Vol. 47, No. 5, 3-14, 2011. 
  • Cerqueira, Jr., A. S., J. M. C. Boggio, A. A. Rieznik, H. E. Hernandez-Figueroa, H. L. Fragnito, and J. C. Knight, “Highly efficient generation of broadband cascaded four-wave mixing products,” Express, Vol. 16, 2816-2828 2008. 

Brief description: The main goal of the thesis is to setup software-defined networking (SDN) testbed capable of performing inbound network traffic classification in real-time. This involves both configuration of network equipment, currently available at Institute of Telecommunications and running simulations in Python environment with Keras framework to prepare the classifier. Afterwards, the prepared classifier can be implemented also in Python language in SDN controller.

Students will be able to use the Universidad Politécnica de Cartagena equipment or the remote access provided by RTU for SDN configuration and classifier set up required for the development of the practical / experimental parts of the master’s thesis.

Brief description: This thesis focuses on classification of many (10-15) types of network traffic of the different nature (i.e. voice, video, file transfer, gaming, etc.). In order to create such a classifier, it is necessary to select correct network traffic parameters (features) for the model. Another important task is to find an appropriate model configuration. All these tasks require extensive simulations in Python with Keras framework in order to perform search for optimum configuration. This also involves statistical analysis of the results. All these tasks can be performed on any computer, however, if it is necessary, remote access to pre-configured computer with CUDA enabled GPU will be provided by the RTU Institute of Telecommunications.

Brief description: the thesis will focus on the evaluation of error correction codes in conjunction with various types of modulation formats. FEC coding is one of the most cost-effective methods, which is a vital indispensable part of any digital communication system. Nowadays almost all systems use EEC codes being integrated as a part of the communication system scheme to achieve a high bit-error-rate (BER) at a low cost. ECC is used to detect errors during transmission over the communication channel and potentially to correct these errors. For the study, block cyclic codes will be used together with higher order modulations.

Tools used: MATLAB, Python

Additional literature:

  • Digital Video Broadcasting (DVB); Second Generation Framing Structure, Channel Coding and Modulation Systems for Broad-casting, Interactive Services, Newsgathering and Other Broadband Satellite Applications (DVB-S2); ETSI: Valbonne, France, 2009.
  • FEC IP Cores; ECC66100 Series; Viasat: Cuyahoga Heights, OH, USA.
  • Borysenko, O.; Matsenko, S.; Novhorodtsev, A.; Kobyakov, O.; Spolitis, S.; Bobrovs, V. Estimating the indivisible error detecting codes based on an average probability method. East. -Eur. J. Enterp. Technol. 2020, 6, 25–33. https://doi.org/10.15587/1729-4061.2020.218076.
  • Li, B.; Larsen, K.J.; Zibar, D.; Monroy, I.T. Over 10 dB net coding gain based on 20% overhead hard decision forward error correction in 100 G optical communication systems. In Proceedings of the 2011 37th European Conference and Exhibition on Optical Communication, Geneva, Switzerland, 18–22 September 2011; p. Tu.6. A.3.
  • ITU-T, “Forward Error Correction for High Bit-Rate DWDM Submarine Systems”. 2013. Available online: https://www.itu.int/rec/T-REC-G.975.1/en

Brief description: The data compression algorithm is a specific method that can be used to minimize the amount of data sent or received, thereby reducing power consumption during communication. The master thesis will research the Huffman coding in telecommunication systems. Huffman coding is a method of source coding, the task of representing a string of symbols from a source by the shortest bit of the string that is possible. Here, using Huffman coding in relation to the probability of occurrence from the root to the leaf node, a binary tree can be constructed. The Huffman coding algorithm takes in information about the frequencies or probabilities of a particular symbol occurring. The master thesis will carry out a comparative analysis of compression algorithms, research the Huffman algorithm, calculate the entropy of the source for use in telecommunication systems.

Tools used: MATLAB, Python

Additional literature:

  • ISO/IEC 21989:2002.
  • Canterbury corpus descriptions. http://corpus.canterbury.ac.nz/descriptions/, 20100517.
  • Donald E. Knuth. Dynamic huffman coding. Journal of Algorithms, 6:163–180, 1985.
  • David Solomon. Data Compression – The Complete Reference. Springer-Verlag New York, 2000.
  • Ian H. Witten, Radford M. Neal, and John G. Cleary. Arithmetic coding for data compression. Communications of the ACM, 30(6), 1987.
  • Jeffrey S. Vitter. Dynamic huffman coding. ACM Transactions on Mathematics Software, 1989.
  • Khalid Sayood. Lossless Compression Handbook. Academic Press, 2003.
  • David A. Huffman. A method for the construction of minimum-redundancy codes. Proceedings of the I.R.E., 1952.

Brief description: experiments in the lab and real infrastructure.

This topic focuses on the research of the optical (based on fiber Bragg grating (FBG) technology) strain and temperature sensor applications in real-time road structural health monitoring.  Annually more and more new roads are being built all around the world. Due to different aspects, e.g. climate, various seasons, weather changes, and a high usage of transportation, as well as natural depreciation over time, there is a need for reconstruction of the older roads that are used on a daily basis. Knowing the fact that the total population of humankind increases and communication technological aspects develop rapidly, it is safe to say that infrastructure for a physical connection between places will be needed further on, more than ever. According to the aforementioned – to save resources, ensure public safety, and provide longer-lasting infrastructure, a structural health monitoring (SHM) application for roads should be researched and developed. Asphalt is one of the mainly used surface materials for the road building industry. This material also provides a relatively easy fiber optical sensor technology instalment, which can be effectively used for SHM applications – road infrastructure monitoring as well as for resource optimization when road building or its repair is planned.

FBG sensor technology is one of the most promising and widely used mainly due to its significant advantages like passiveness, size, multiplexing ability, high sensitivity, remote sensing capabilities and resistance to electromagnetic interference.

Experiments and measured results are very topical for local and international road pavement designers and road management service to forecast collapsing of the road, permanent deformation, vehicular weight and number of axles, traffic monitoring, and road pavement temperature monitoring.

Practical part:  simulation software and experiments in the Lab.

The aim of this topic is to detect the optimal grating profile and its parameters for created a sensor network for SHM application. While doing so, it is planned to ensure high sensitivity and convenient integrity realization. Also, ensuring FBG reflection spectrum with narrow bandwidth at the -3dB level, high side lobe suppression ratio and reflectivity, as well as maximally symmetric shape asymmetry ratio factor, etc. The research will be carried out in some of the simulation software (e.g. VPIphotonics, OptiGrating, Matlab, etc.). FBG sensors’ gratings networks will be realized according to the determined optimal profile and parameters. Produced FBG sensors’ gratings will be thoroughly tested and validated within the environment of RTU IT laboratory.

Brief description:  The fifth-generation (5G) mobile communications will have a great impact on different use cases such as stadiums, hospitals, railway stations, and homes as well as businesses using conventional wireless access technology. 5G will feature data transmissions up to tens of gigabits, ultra-low latency, and high-reliability communication. On one hand, this will change and significantly improve several different applications like the Internet of Things (IoT), augmented and virtual reality (VR), and super high-resolution video streaming (4K/8K). On the other hand, 5G technology still needs to satisfy stringent key performance indicators (KPIs) such as higher bandwidth and data-rate per user, increased number of connected devices, lower energy consumption, and reduced end-to-end latency. Considering the required capabilities of 5G and beyond 5G mobile radio communication networks and their techniques, an optical fiber can be considered as the primary complement for 5G/beyond 5G fronthaul and backhaul networking.  

The thesis will focus on designing of millimeter-wave (mm-wave) hybrid photonics-wireless access systems, the evaluation of minimal channel interval for wavelength-division multiplexed (WDM) fiber optical communication systems with Radio over Fiber (RoF) transmitters. Minimal channel interval (GHz), usually is based on ITU-T G.694.1 recommendation (100, 50, 25, 12.5, 6.25 GHz, etc.). The thesis can focus on the investigation of communication system performance with different modulation techniques (such as non-retur-to-zero (NRZ) or four level pulse amplitude modulation (PAM-4)) with a various number of channels (e.g. 8, 16, 32).  

Tools used: Synopsys OptSim (modeling and simulations of fiber optical communication system), MATLAB (for data representation, analysis)  

Additional literature:  

  1. T. Salgals, A. Ostrovskis, A. Ipatovs, V. Bobrovs and S. Spolitis, “Hybrid ARoF-WDM PON Infrastructure for 5G Millimeter-wave Interface and Broadband Internet Service,” 2019 Photonics & Electromagnetics Research Symposium – Fall (PIERS – Fall), 2161-2168, (2019). 
  2. A. Udalcovs, T. Salgals, L. Zhang, X. Pang, A. Djupsjöbacka, S. Spolitis, V. Bobrovs, S. Popov, and O. Ozolins, Optical Power Budget of 25+ Gbps IM/DD PON with Digital Signal Post-Equalization. Appl. Sci. 2020, 10, 6106.  
  3. T. Salgals, I. Kurbatska, V. Bobrovs, and S. Spolitis, “Research of PAM-4 Modulated WDM-PON Architecture for 5G Millimeter-wave Hybrid Photonics-wireless Interface,” 2019 Photonics & Electromagnetics Research Symposium, 728–734 (2019). 

The topic of this thesis involves estimation of electromagnetic compatibility (EMC) of 5G networks in cochannel case in 2.1 GHz band. Overview of 5G main technical and radio parameters. Development of experimental 5G networks using SEAMCAT simulation software and make appropriate EMC evaluation of these networks.

The topic of this thesis involves an assessment of 5G base stations parameters impact on mobile coverage. Overview of 5G main technical and radio parameters. Development of experimental 5G network using HTZ Communications simulation software and performance of mobile coverage simulations of the developed network.

Senior researcher Elans Grabs

SDN Testbed Setup for Network Traffic Classification with Deep Learning Models

The Study on Features Selection for Multi-Class Network Traffic Classification with Deep Learning

Senior researcher Svitlana Matsenko

Evaluation of Forward Error Correction (FEC) codes with Optical Modulation Formats

Data Compression in Telecommunication Systems

Researcher Janis Braunfelds

Fiber Bragg Grating Sensors for Structural Health Monitoring of Road Infrastructure

Development of Fiber Bragg Grating Profile for Sensors Network Solutions

Researcher Toms Salgals

Radio over Fiber technology usage in Fiber Optical Transmission Systems for Communication Implementation 

Senior researcher Guntis Ancans

Assessment of 5G Base Stations Parameters on Mobile Coverage

Estimation of Electromagnetic Compatibility of 5G Networks in 2.1 GHz Band Title:  Radio over Fiber technology usage in Fiber Optical Transmission Systems for Communication Implementation 

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