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Browse Prior Art Database

Multi-point Video Transmission Over Token Ring LAN

IP.com Disclosure Number: IPCOM000104868D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 89K

Publishing Venue

IBM

Related People

Aldred, BK: AUTHOR [+4]

Abstract

Disclosed is how existing broadcast mechanisms defined in the Token Ring Network architecture can be used to reduce the bandwidth required to sustain an N-way video conference over Token Ring. Group addressing is employed to implement multi-point video conferencing. Video and sound are regarded as spoilable data, so if individual frames do not arrive, acceptable output quality can still be presented.

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Multi-point Video Transmission Over Token Ring LAN

      Disclosed is how existing broadcast mechanisms defined in the
Token Ring Network architecture can be used to reduce the bandwidth
required to sustain an N-way video conference over Token Ring.  Group
addressing is employed to implement multi-point video conferencing.
Video and sound are regarded as spoilable data, so if individual
frames do not arrive, acceptable output quality can still be
presented.

      Person-to-Person (P2P) conferencing represents the convergence
of high performance communication channels (e.g., LAN, ISDN) with
advanced workstation and multi-media technologies (e.g., video
compression), to provide interactive communication of data, voice and
video between desktop workstations.  Like teleconferencing, it
permits collaboration without users having to be in the same place at
the same time.  One type of data which is communicated between P2P
users is motion video which requires hardware such as the Intel/IBM
ActionMedia II (AMII) card set to capture, compress, decompress and
display full-duplex motion video information streams.  Typically, P2P
users communicate using a shared network such as the Token Ring Local
Area Network which can provide a data rate of 4 or 16 megabits per
second.  Video data streams can be from 64kbit/s for a small, low
resolution image being refreshed 15 times per second, to 2Mbit/s for
an image of TV resolution and refresh rate.  Personal video
conferencing on a Local Area Network (LAN) involves the transmission
of digital compressed video from all users to all other users.  For a
point-to-point operation the network bandwidth required to transmit
full-duplex video between the two users (two channels) is acceptable.
For multi-way conversations, the number of separate video channels
increases to N(2)-N, where N is the number of parties in the
conference.  The combination of the high data rate demands of video,
combined with the growth in video channels as the number of
conference participants increases, leads to an demand for network
bandwidth which can easily outstrip that available.  A technique
which reduces bandwidth requirement is therefore beneficial.

      Standard Token Ring architecture supports a number of broadcast
addressing mechanisms at the Media Access Control (MAC) level.  These
are:  All Stations, Group Addressing and Functional Addressing.

      The All Stations Broadcast Addresses allow ALL stati...