Willem Jules Antoine Verbiest

The impact of the ATM concept on video coding

The induction of the asynchronous transfer mode (ATM) concept may significantly influence the coding of video services for broadband networks. The authors show how the absence of a physical channel structure and the ability to switch bursty traffic can be used to enhance video coding. Packetization defects and their impact on picture quality, coding algorithms, and synchronization schemes are studied. The authors describe variable-bit-rate coding and report on the results obtained with a hardware implementation of a variable-bit-rate video codec. Statistical multiplexing gain figures are given. The influence of cell loss on image quality is discussed and simulation results are given. A layered coding model offering good cell loss concealment properties and high flexibility is described. >

Interactive video on demand

Video on demand (VOD)/spl minus/likely to become one of the most successful services in the emerging broadband network/spl minus/must minimize bandwidth requirements to serve large numbers of users. This article describes two VOD service variants, whereby bandwidth requirements in the network are reduced, while keeping the quality of service (QoS) at an equally high level.<<ETX>>

A variable bit rate video codec for asynchronous transfer mode networks

The bandwidth flexibility offered by the asynchronous transfer mode (ATM) technique makes it possible to select picture quality and bandwidth over a wide range in a simple and straightforward manner. A prototype model of a video codec was developed that demonstrates the feasibility of both variable bit rate (VBR) coding and user-selectable picture quality. The VBR coding algorithm is discussed and it is shown how a stabilized quality is achieved and how this quality and associated bandwidth can be selected by the user. How error propagation is limited to reduce the visibility of cell losses is also discussed. Interfaces with the ATM network are analyzed, with emphasis on decoder synchronization and absorption of cell delay jitter. The VBR codec offers very good picture quality for videophony applications at an equivalent load of 5.9 Mb/s. Picture quality remains relatively constant, even for heavy motion. >

FITL and B-ISDN: a marriage with a future

A cost comparison for different broadband access network configurations in the context of fiber-in-the-loop (FITL) is presented. The basic architecture and features of the asynchronous transfer mode (ATM) passive optical network (APON) are described. The design objectives of each of the APON building blocks are clarified, and their relation to the system philosophy is indicated. The building blocks include systems for transport over the PON, operation of the user equipment, and interworking with existing networks.<<ETX>>

Statistical multiplexing of variable bit rate video sources in asynchronous transfer mode networks

The advent of the asynchronous time division (ATM) concept has created the opportunity to use variable bit rate (VBR) coding techniques for the coding of video services in broadband networks. The principles of VBR coding are explained, and the benefits-stabilized picture quality combined with a high bandwidth efficiency-are indicated. The results obtained with a hardware model of a VBR video codec are presented, and statistical multiplexing gain figures are given. A bandwidth allocation scheme is proposed that is based on the statistical characterization and policing of the VBR sources. It is concluded that this scheme offers high performance with a limited impact on the network and encoder complexity.<<ETX>>

ATM over passive optical networks: system design and demonstration

Passive Optical Networks (PONs) have been demonstrated to be cost-attractive approach for the deployment of Fiber-In-The-Loop systems (FITL) having POTS services capability. In the future these systems must be able to carry broadband services in ATM format as defined by CCITT. The present paper describes an ATM-based PON (APON) and presents the results of feasibility tests for the most critical parts of the system: high-speed medium access protocol for upstream transmission (TDMA), burst mode clock synchronization technique and high- speed electro-optic transceivers applicable to burst mode transmission. System design options such as the downstream and upstream bit rates, the sharing factor and the multiplexing technique used for the bidirectional transport of ATM cells are discussed. Issues such as analog CATV services delivery and the provision of digital video-on-demand (VOD) are covered as well.

Demonstration of an ATM-based passive optical network in the FTTH trial on Bermuda

Multimedia communication has become the driving force for installing broadband systems in the public network. Different alternative solutions have been presented to realise a broadband interactive access network, such as installing optical fiber or upgrading the existing copper network with ADSL for twisted pair or hybrid fiber-coax for CATV networks. Among these alternatives, optical fiber access networks are seen as the most future safe solution. Especially passive optical networks have shown to be a cost effective way to introduce fiber in the access network today. This paper presents an ATM-based passive optical network (APON) that has been installed for a video on demand (VOD) trial on Bermuda. An overview is given of the configuration of the network and of the operation of the VOD service. The basic principles of the operation of the APON access network are presented.