Jelena Kovacevic

A Statistical Approach to Model-Based Robustness Testing

Recent massive research in the area of robustness testing of communication protocols have been driven by the fact that embedded systems are becoming more and more complex every day. Providing correct implementations of communication protocols is a key to successful interconnection of embedded system constituents. Test and verification is the last and the most critical phase in the production of the corresponding software artifacts. This paper contributes to the overall research effort in the area by proposing an original approach to model-based robustness testing of communication protocols. In the paper we introduce the notion of hidden FSM states and state transitions. We also show how to calculate the probabilities of detecting the existence of the hidden state transitions. Then we present our methodology of model-based robustness testing of communication protocols. The methodology is based on the special operational profiles, which are referred to as the stress operational profiles

Voice control system with advanced recognition

This paper explains the process of realization of voice control system based on the cloud processing. The aim is the feasibility study of system based on integration with Google STT API (Speech to text, recognition and speech synthesis) for different platforms. This approach introduces advanced recognition module that operate on text level. Improving recognition leads to further improvement of the overall system behavior.

Evaluation of adaptive streaming algorithms over HTTP

In order to guarantee the best user experience throughout different network access technologies with dynamically varying network conditions, it is fundamental to adopt new technologies enabling a proper reception of the multimedia content. In this paper we implemented a prototype of streaming client, based on the MPEG DASH standard. We experimentally evaluated three adaptive streaming algorithms proposed by different authors in order to answer the following questions: (i) how fast is the reaction time to bandwidths changes? (ii) algorithm behavior on a highly unstable network conditions and (iii) buffer underrun/overflow. We identify differences, inefficiencies and possible improvements.

Advanced rate adaptation algorithm in video streaming over HTTP

In order to guarantee the best user experience throughout different network access technologies with dynamically varying network conditions, it is fundamental to enable proper reception of the multimedia content. To overcome the limitations/deficiencies of evaluated adaptive streaming algorithms (such as slow rate adaptation at stable network conditions), we propose an Advanced Rate Adaptation algorithm (ARA, in the following text) and test it under various network scenarios. The algorithm is implemented as a part of the MPEG DASH compliant client.

Joint coding rate control for audio streaming in short range wireless networks

Streaming high quality audio/video (AV) from home media sources to TV sets and audio speakers over a wireless local area network (WLAN) is a challenging problem because of the fluctuating bandwidth caused by interference and fading. Retransmission and data buffering, as common techniques in data transfer over error-prone channels, are not adequate for delay sensitive applications such as high quality audio streaming. Our approach is to adjust the audio data rate dynamically in order to improve the perceptual quality of audio according to wireless channel quality. In this paper we specifically focus on robust audio streaming over short range wireless channels. The major strength of the proposed algorithm is in its ability to match the source and channel coding parameters to the given channel conditions, thus providing better quality and lower latency of audio in home networking.

Real time FPGA implementation of brushless DC motor control using single current sensor

In modern industry power consumption is becoming one of the most important constraints during the development phase of the product. In motor industry, significant part of the power consumption improvement can be done in motor control. Brushless dc (BLDC) motor drives are penetrating the market rapidly. Heating, ventilation and air conditioning (HVAC) systems use conventional motor drive technology and the machines found in these devices are characterized by low efficiency and high maintenance. BLDC motor drives are characterized by higher efficiency, lower maintenance and higher cost. This paper presents the analysis, design, and implementation of a cost-effective control technique for a low cost solution, six switch three-phase inverter brushless dc motor drive using single current sensor for current control. Various parameters defined optimization path for target drive solution. Also, basic framework for low cost BLDC control IC is presented. The controller is modeled and the concept is proven using simulator. Then the verification and feasibility study are done by using field-programmable gate array prototyping on the custom board made for this research. Final simulation results along with prototype operation measurements are presented as well.

Partitioning DSP Applications on a Multi-core Architecture Based on Load Balancing

In this paper, we describe the technique for optimization of demanding DSP applications on a dual core DSP-s. In addition to common techniques of optimization, we use the Advanced Multi-core Optimization Technique, resolving load balancing problem. The methodology of the proposed technique is based on the application partitioning on two cores, assuming algorithm and processor architecture understanding. To verify the described technique we used one class of lossless audio decoder on CS4953xx dual core processor.

Sat>IP client integration in a DVB software stack

In order to leverage the full potential of video playback capabilities in modern connected devices new protocols for content delivery are emerging. Sat>IP protocol is gaining popularity as a new IP-based architecture for reception and distribution of satellite signal. In this paper we present one solution for integration of Sat>IP client in an existing DVB broadcast software stack. Seamless integration is enabled by using virtual IP tuner concept for content acquisition. The solution is implemented on an Android based embedded DTV platform.

Sat>IP server implementation on an embedded platform

In order to leverage the full potential of video playback capabilities in modern connected devices new protocols for content delivery are emerging. Sat>IP protocol is gaining popularity as a new IP-based architecture for reception and distribution of satellite signal. In this paper we present implementation of Sat>IP server on Linux embedded platform and propose programming techniques which allow achieving maximum available streaming throughput.

Real-time AV synchronization delay measurement for multimedia devices

In this paper, a non-intrusive approach for measuring Audio/Video (AV) synchronization delay for wide range of multimedia devices is presented. The approach combines QR codes and sweep markers to enable cost-effective AV delay measurement in real-time. The concept relies on transmission of reference signal from source to the end-device and rendering on it. The output of the end-device is captured with any available camera. The audio/video delay is extracted from the captured content. The complexity of the measurement process allows execution in real-time on embedded platforms. It is also tolerant to occasional losses and degradations in the signal.