https://etalpykla.vilniustech.lt/handle/123456789/159385 Sat, 11 Apr 2026 17:54:10 GMT 2026-04-11T17:54:10Z https://etalpykla.vilniustech.lt/handle/123456789/159443 QoS efficiency for individual user in 3G networks Žvinys, Karolis; Guršnys, Darius Packet data traffic volume and a packet switch related services climb upward in UMTS (Universal Mobile Telecommunications System) networks. Services provided on a live network became very complex and require different QoS (Quality of Service). 3GPP defines four service types: conversational, interactive, streaming, and background, which can be managed, in terms of quality, to ensure differentiated services for end users. HSPA (High Speed Packet Access) Diff- Serv management provides facilities based on service type and user priority. Different user profiles allow to maintain high level services and to control users in networks based on the load. The goal of this research is to estimate the efficiency of quality management based services for individual user on UMTS network. End user experience is most concerned question of this research. The users attempting background traffic class service are investigated. According to this, three different users (Gold, Silver, Copper) are distinguished, which are formed by combining SPI (Scheduling Priority Indicator) and ARP (Allocation/Retention Priority) parameters related to QoS assurance. Practical part of study is performed on a commercial mobile network. Provided results reflect the user experience and impact for the 3G network. Thu, 01 Jan 2015 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/159443 2015-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/159442 Design of a time-gain-compensation amplifier for ultrasonic echo signal processing Vasjanov, A.; Barzdenas, V. This article presents a design concept of a time-gain-compensation (TGC) amplifier integrated circuit (IC) for ultrasonic echo signal processing. The TGC chain contains pre-amplification, attenuation, filtering and comparison circuit blocks. An on-chip oscillator, bias circuit and digital control core are also included. The presented TGC IC concept blocks are designed and modeled using Cadence's IC design tools using a 250 nm CMOS process. The operational amplifier implemented in the TGC IC has a gain of 35 dB with a -3 dB bandwidth of 750 kHz, which corresponds to ultrasonic signal frequency range. The second order active band pass filter is of a Sallen-Key topology with a 274 MHz center frequency and a filter quality factor of Q = 1.018. A ring oscillator with external tuning capability is modeled at 448 kHz and has a 0.09 % frequency deviation. The ultrasonic echo processing chain has a digital output where the length of the pulse corresponds to the received signal strength. This makes the presented TGC IC concept suitable for both simple and complex ultrasonic, medical, industrial or research equipment. Thu, 01 Jan 2015 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/159442 2015-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/159441 Business process event log use for activity sequence analysis Savickas, Titas; Vasilecas, Olegas It is mandatory for nowadays businesses to improve their processes to survive. The basis of this improvement is business process analysis. The analysis can be done in multiple ways but one of the state of the art solutions is Process Mining which uses historical business process execution data in information systems to improve the process analysis. The historical data for analysis comes in a form of event logs. In this paper an approach is presented which processes an event log into frequency matrixes to allow efficient activity sequence analysis. Additionally, some heuristic rules are presented that allow to make inference on causality between activities in a business process. Thu, 01 Jan 2015 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/159441 2015-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/159440 Dynamic business process model implementation solutions Rusinaitė, Toma; Vasilecas, Olegas Business processes in enterprise are changing due to changes in the environment of business systems. These changes need to be implemented with very low latency because it is necessary to maintain competitiveness. Usually it requires a lot of resources (finance, time and people to change the business process components: activities (their contents, executors and consistency) and conditions. It is desirable for the changes to be implemented at the business processes runtime so that they would ensure the dynamism of the business process. This paper presents the dynamic business process definitions proposed by individual authors, examines the dynamism problems, and presents architectural solutions to these problems. Thu, 01 Jan 2015 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/159440 2015-01-01T00:00:00Z