Valentin Andrei

Development of an IEEE 802.21 Media Independent Information Service

This paper provides a view on the developing process of the Media Independent Information Service, later referred as MIIS, described in the IEEE 802.21 standard, which has the main functionality of providing the mobile terminal information about all access points in his coverage area. Our approach is towards the management of the entire mechanism of delivering data to the device, that is realized at a central location. The first chapter describes related work on IEEE 802.21 standard, and it-s linkage with the MIIS entity. The following chapters present the general architecture of the system, important aspects of implementation, the used technologies and also a set of research directions. The final section presents a performance evaluation, giving us a clue about the systems real functioning and serving capabilities.

Solution for implementing IEEE 802.21 Media Independent Information Service

This paper describes a solution for implementing the Media Independent Information Service, later referred to as MIIS, described in IEEE 802.21 standard. First we present the previous work towards defining a complete system capable of realizing a vertical handover according to the standard. Next we detail the MIIS general architecture, the information gathering procedures and considerations about the data format used in communicating. The last section presents a typical usage scenario and the advantages of implementing MIIS.

Real-time monitoring design of a wireless network device for vertical handover on multimod terminals

In this paper we propose a software module for continuously monitoring a wireless network card, able to handle and rise IEEE 802.21 compatible primitives in support for vertical handover in heterogeneous networks. This module is intended to be installed on a multimod mobile terminal, and will automatically monitor and switch the connection link, when performing vertical handover. Besides the software architecture, we describe the real-time behavior of the module by using state machine diagrams.

Context-aware reconfigurable interoperability for vertical handover in wireless communications

In this paper we describe a context-aware reconfigurable system, which implements the IEEE 802.21 Media Independent Handover (MIH) standard for interoperability between wireless hybrid access networks. The proposed approach uses vertical handover prediction algorithms to improve the resource management decisions, through access to our Web Service implementation of the Media Independent Information Service (MIIS), which stores previously acquired information about surrounding hybrid access networks. Various prediction alternatives are discussed, and two proposed algorithms are evaluated, on our prototype implementation of the system.

A streaming application for vertical handover testing in wireless hybrid access networks

In this paper we describe a media streaming application build to test a system which implements the IEEE 802.21 Media Independent Handover (MIH) standard, for interoperability between wireless hybrid access networks. We evaluated the real-time performance of our vertical handover prototype system by means of the audio streaming continuity assessment. The current results proved only moderately performances, but they also showed us which components have to be improved. Further developments will address these improvements, and will extend the application with video streaming capabilities.

Considerations over implementing IEEE 802.21 on a device powered by a mobile operating system

During the last years, software applications performing scenarios related to vertical handovers were revealed. However, the great majority of these demonstrators were designed and optimized for multimode notebooks, having a fair amount of processing power. This article aims to describe on how to implement and optimize the main components of the IEEE 802.21 standard on a device like a smartphone powered by a mobile operating system. Performance evaluations were made in this purpose showing reasonable delays, taking us one step closer to achieving a seamless vertical handover on a mobile terminal.

A software demonstrator for IEEE 802.21 Media Independent Handover in heterogenous networks

In this paper we present a software demonstrator, for a system built following the directions described in the IEEE 802.21 (Media Independent Handover) standard, capable of completing an independent vertical handover. We first bring in front the fields related work, and also propose methods of implementing the components described in the standard. The architecture and the functionalities of the demonstrator application are detailed, and we also mention aspects about surpassing the difficulties that rise during the implementation process.

Estimating competing speaker count for blind speech source separation

We present a method for estimating the number of simultaneous speakers for direct integration with blind speech source separation algorithms. The method was developed to use single microphone recordings but is fully compatible with microphone-array approaches. Speech source separation algorithms based on independent component analysis, multiband analysis or spectral learning need the number of concurrent speakers as an input parameter. This is estimated based on pattern matching techniques between the spectrogram of the speech mixture and the ones associated to a set of single speaker references. The method demonstrated to scale up until at least 10 concurrent speakers. Additionally we highlight the separation performance of various speech separation algorithms using mixtures with 3 competing speeches.

Video streaming for evaluation of predictive VHO in wireless hybrid access networks

The paper describes a video streaming application build to evaluate session continuity over wireless hybrid access networks in vertical handover (VHO) conditions. The results showed us which components have to be improved. Further developments will address these improvements.

Implementation of a real-time text dependent speaker identification system

Speaker recognition has received for many years the attention of researchers working in the field of signal processing, but has not yet been implemented as a reliable feature in widely spread applications. We present in this paper a real-time text dependent speaker identification application, designed to consume a low amount of memory and processing power, serving as intermediary step towards the implementation as an embedded system. The speaker identification is based on computing the Mel Frequency Cepstral Coefficients and the derived Dynamic Coefficients, while classifying features using a Dynamic Time Warping approach. The software was tested using recording equipments similar to the ones integrated into mobile devices and shown satisfactory results.