Maria Varsamou

A bluetooth smart analyzer in iBeacon networks

Bluetooth Low Energy (BLE) is a newly emerged technology targeting low-power, low-cost wireless communications within medium or short range. BLE has extended the already wide acceptance of Bluetooth and is an ideal choice for a variety of sensor-based products, as well as ubiquitous mobile devices. Recently, it has been proposed that indoor positioning can be achieved when scattering BLE sensor devices, called iBeacons, in various locations of a particular venue. In this work, we present an Android-based application for analyzing iBeacon networks and determining the best signal map. We also demonstrate the application of the presented analyzer for measuring the radiation pattern of iBeacon devices.

A New Data Allocation Method for Parallel Probe-Based Storage Devices

We present a new data allocation method for probe-based storage devices that use multiple, simultaneously accessed parallel data fields. Our method uses blocks of data of unequal length for allocating a sector in the various storage fields. The amount of data stored in each field depends on the sectors offset from the beginning of the allocation round and on the storage field used. Numerical results demonstrate the storage efficiency improvement that is achieved by the proposed method. We show that this method can be applied to atomic force microscopy-based probe storage devices.

Transmission systems prototyping based on Stateflow/Simulink models

In this paper we describe an efficient methodology for rapid prototyping of data transmission systems based on Stateflow/Simulink models using a multi-level system development and testing approach. Transmission systems incorporate multi-domain functions and algorithms, i.e. physical layer circuits and communication protocol controllers. The Stateflow/Simulink environment enables the development of precise simulation models that include signal and protocol processing units. The proposed prototyping methodology is based on the progressive translation of high-level model blocks into hardware/software modules of the prototype architecture using custom and/or automated code generation tools. A custom data exchange and synchronization interface between the Stateflow/Simulink workspace and the circuit modules enables the integration of the simulation model and the prototyping platform into a complete functional system. The application of the proposed methodology in the development of an ADSL modem in a custom prototyping platform is also described.

From protocol models to their implementation: a versatile testing methodology

The design and test of communication protocols relies extensively on formal description languages. In this protocol design and verification scheme, high-level models serve in generating simulation sequences for low-level models, and all simulation is based on directed testing. The methodology is versatile and flexible, and difficult to set up the first time.

xDSL systems prototyping using a flexible emulation environment

In this paper we describe the methodology and architecture of a flexible modular environment for prototyping data transmission systems and its application on xDSL systems. The development environment is based on custom and commercially available software tools and a custom hardware emulation platform for mapping the basic data-pump modules of xDSL systems into hardware/software functional modules. The road-map from a high-level xDSL system model to the actual prototype is based on the progressive substitution of high-level submodules of the initial model with their respective hardware/software counterparts, and their integration into a complete functional system. A library of custom blocks is used for data exchange and synchronization between the high-level model and the emulation platform, and for real-time visualization of the critical parameters of the emulated system as well. The application of the proposed development environment in the implementation and testing of an emulator of a bundle of DSL lines and of a centralized bit-loading algorithm for multicarrier ADSL systems is also described.

Variability of NVM response time and its effect on the performance of consumer SSDs

Solid-State Drives (SSDs) use non-volatile memories (NVM) for storing and retrieving information in the form of sectors and/or pages. For achieving high capacity, consumer SSDs use high density multi-level cells (MLC) memories that experience high read and write times. The maximum achieved I/O performance and the minimum response time depends on the used NVM technology, which determines the read and write times, and other system parameters, like the number of simultaneously accessed NVM channels, the SSD controller architecture, its functionality, the supported commands and the applied workload. Most of these parameters remain unchanged during the lifetime of an SSD, except for the read and write times which vary as the lifetime of the device progresses and higher variability is observed. By defining the basic equations of the maximum SSD performance and using experimental results, we determine how the increase of the NVM response time affects the performance of a consumer SSD and under what conditions this is observed by the SSDs user.

Anti-aircraft artillery simulator

Air defense systems protect land and maritime resources from air attack. Depending on the regional characteristics and type of conflicting forces, air defense threats vary considerably. In regional conflicts, where forces with similar capabilities are involved and no air-superiority can be achieved, the role of air defense systems becomes critical. In combat terrains containing mountains (in mainland or in small islands), the man-operated or computer-controlled (using passive sensors) anti-aircraft artillery can be highly effective. The simulator presented in this work aims to exploit the capabilities provided by current commercial-off-the-shelf (COTS) communication and multimedia technologies for providing a training environment that improves the personnel capability for effective use of man-controlled anti-aircraft weapons.

A heuristic method for error correction in parallel probe-based storage devices

This paper presents a new decoding algorithm that improves the reliability of probe-based storage devices, that usemultiple, simultaneously accessed parallel fields, when they are affected by burst errors. The presented algorithm exploits the parallelism of the multiple storage fields and the used data allocation method and flags symbols as erasures using the error locations revealed by the initial errorsonly decoding attempt. Numerical results demonstrate the performance improvement that is achieved by the proposed algorithm.

Hardware Acceleration on Cloud Services: The use of Restricted Boltzmann Machines on Handwritten Digits Recognition

Article history: Received: 30 November, 2017 Accepted: 07 January, 2018 Online: 18 February, 2018

Prototyping and performance evaluation of a dynamically adaptable block device driver for PCIe-based SSDs

Solid-state drives use non-volatile memories for storing and retrieving information in the form of sectors and/or pages and demonstrate better performance than hard disks. In many cases, the maximum IO performance of the used memory technology is not achieved due to limitations imposed by the software device driver that interfaces the storage card with the hostss operating system. Todays computing machines with conventional operating systems have been developed based on the performance characteristics of hard disk drives. In this work, we present the prototype of a new block device driver with a flexible host-device interface suitable for PCIe-based solid-state drives. The block device driver is compatible with the standard software dataflow of a Linux-based OS, and at the same time exploits the operational features of such devices to provide improved performance. Experimental results that demonstrate how the system performance is affected by decisions on the device drivers functionality are presented along with the used testing methodology.