Mobile Blog: Video, Media, Augmented Reality, Rich Media, IVVR

High-level system architecture for the delivery of dynamic IVVR (Interactive Voice & Video Response) services

Commercially available IVVR appliances [For example, DTG 3000 from Dilithium is a combination of MCU (Multipoint Control Unit), 3G-324M Gateway, and transcoder] still focus on dialog-based services and use VoiceXML to create IVVR applications that are generally IVR (Interactive Voice Response) Supplements, without sophisticated features like real-time video generation or camera-based interaction. This hinders the creation of advanced IVVR applications as mentioned in Section 4. Such applications are generally founded on pre-recorded or pre-generated video sequences that are played back based on speech commands or keystrokes. To create a more flexible solution that is capable of delivering games and interactive services, sounds, and graphics need to be generated in real time. The current research and testing results recommend the configuration featured in the figure on the left.

Adobe Flex has evolved into a suite of technologies appropriate for the creation of rich media applications and games. For the solution presented in this research, Flash is employed as the Game Engine as it is very flexible and can be extended to create 3D games [By using the open source real-time 3D Engine Papervision3D]. The Flash application is not run on a handset, but the audio and video it creates are transmitted over a 3G-324M session to a handset so they can be controlled based on the handset

Download my A-graded thesis. Abstract: Interactive voice and video response (IVVR (Interactive Voice & Video Response)) is a mobile technology enabling interactive services based on 3G video telephony. IVVR applications can take advantage of bidirectional real-time multimedia streaming, enabling speech and camera-based interaction. Games are a proven way to draw users into new technologies. This thesis analyses IVVR

photo credit: Steven Fernandez

Media compression, error concealment measures, and the characteristics of wireless networks have side effects on the quality of 3G video telephony and IVVR (Interactive Voice & Video Response) applications.

3G-324M requires only the use of speech codecs. In contrast to audio codecs, speech codecs are designed for speech transmission within a narrow frequency range, making them inappropriate for transmission of music or a range of artificial sounds. This fact needs to be considered when designing IVVR applications

3G systems were designed with the notion of enabling a single global standard to fulfil the needs of anywhere and anytime communication (Etoh). Compared to 2G (Second generation mobile networks, services and technologies) systems, 3G systems focus more on multimedia communication such as video conferencing and multimedia streaming. ITU (International Telecommunication Union) defined IMT-2000 as a global standard for 3G wireless communications and, within this framework, 3GPP (3rd Generation Partnership Project) developed UMTS (Universal Mobile Telecommunications System) as one of today

photo credit: iboy_daniel

In the following I describe how the characteristics of wireless networks affect the audiovisual quality of 3G video telephony and especially IVVR (Interactive Voice & Video Response) applications. The impact of these characteristics need to be considered when designing IVVR applications and services:

Wireless networks are inherently error prone. Bitrates in wireless systems tend to fluctuate more as compared with wired networks. In wired networks, phenomena such as fading, shadowing, or reflection are non-existent so that, for the most part, the same bandwidth and much higher bandwidths are present during transmission. Influences on signal propagation cause the constant changing bandwidths in wireless systems. Generally, the receiving power depends on the distance between sender and receiver. The receiving power p decreases proportionally to the square of the distance between sender and receiver:

p=1/d²

where d is the distance between sender and receiver (Schiller).

Receiving power is influenced further by frequency dependent fading, shadowing, reflection at large obstacles, refraction depending on the density of the medium, scattering at small objects, and diffraction at edges.

The effect of multipath propagation can cause jitter when the radio signal reaches the receiver by two or more paths at different times. Moreover, the mobility of the user adds another set of problems that results in fading of received power over time; the channel characteristics change over time and location. This exacerbates the effect of multipath propagation because signal path change will be increased as the user changes his or her location. Changes in the distance between sender and receiver cause different delay variations of different signal parts.

The phenomenon of