Aufbauend auf den Ergebnissen vorangegangener Arbeiten wird in diesem Beitrag die Erweiterung eines Voice-over-IP-Frameworks um die Möglichkeit, geheime Kommunikation auf Basis von Steganographie durchzuführen, fortgesetzt. Kommunikationspartner einer VoIP-Verbindung sind durch Nutzung des erweiterten Frameworks in der Lage, während einer VoIP-Sitzung geheime Nachrichten auszutauschen. Diese Ar...

Development of a low bit-rate voice over IP application is described. A speech coding algorithm is constructed and implemented on a digital signal processor (DSP). The algorithm is based on a sub-band mixed excitation LPC vocoder structure and operates at a rate of 2000 bits per second. Implementation is done on two TMS320C6701 floating point DSP’s each connected to a PC. On the PC, a graphical...

VoIP (Voice over IP) services are using the Internet infrastructure to enable new forms of communication and collaboration. A growing number of VoIP service providers such as Skype, Vonage, Broadvoice, as well as many cable services are using the Internet to offer telephone services at much lower costs. However, VoIP services rely on the user’s Internet connection, and this can often translate ...

Store and forward Voice-over-IP is a suggested solution for supporting Telemedicine at rural health clinics in developing countries. Solutions described to date are designed to support communication by establishing point-to-point connectivity between two sites. In this paper we present an approach for creating scalable Telemedicine networks based on Delay Tolerant Networking. This holds potenti...

We have analyzed the measurements of end-to-end VoIP packets by tracing UDP packets between 12 testboxes in the Netherlands. We show that voice probes experience low delay and loss in the network. Moreover, we find that the reordering of packets has virtually no impact on the voice quality in our experiments. To determine the quality of VoIP calls over time, we have monitored the end-to-end pac...

This thesis addresses the development of an end-to-end secure Voice over IP (VoIP) conference system. We are particularly interested in challenges associated with deploying such a system in ad-hoc networks containing low bandwidth and/or high latency data links. End-to-end security is handled by the decentralized Public Key Group Encryption library (PKGE) developed at Lincoln Laboratory; PKGE a...

Perceived speech quality is the key metric for QoS for VoIP applications. The primary aims of the study reported in the paper are to carry out a fundamental investigation of the impact of packet loss and talkers on perceived speech quality using an objective method to provide the basis for developing an artificial neural network (ANN) model to predict speech quality for VoIP. The impact of pack...

The first step for the integration of multimedia traffic within the Internet is the provision of voice services, both traditional POTS (Plain Old Telephony Services) and innovative, like multi-party audio conferences or high quality audio. Voice services in Internet are broadly indicated as VoIP (Voice over Internet Protocol), including all possible services that can be built on vocal interacti...

Time, day, location and instantaneous network conditions largely dictate the quality of Voice over IP calls. In this paper we present the results of over 18000 VoIP measurements, taken from nine sites connected in a full-mesh configuration. We measure the quality of the routes on a hourly basis by transmitting a pre-recorded call between a pair of sites. We repeat the procedure for all nine sit...

With the maturity in mobile communication, the new mobile communication systems are shaped up gradually especially for the 3rd Generation. The next generation mobile communication, the 4th Generation wireless System, will be converged on Internet Protocol like wired environment. Although the traffic is not only voice, how the voice over IP in wireless environment can be accepted satisfactory, i...