Multiplex communications – Wide area network – Packet switching
Patent
1994-04-29
1996-04-16
Marcelo, Melvin
Multiplex communications
Wide area network
Packet switching
370118, 348388, 348403, H04N 712
Patent
active
055090176
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process fo simultaneous transmission of signals from N signal sources via a corresponding number of transmission channels.
STATE OF THE ART
Processes in which the individual signals are divided into blocks and these blocks are transformed by transformation or filtering into spectral coefficients which for their part undergo a data reduction process or which are coded according to a data reduction process respectively, are known. In this connection, reference is made to, by way of illustration, the overview article "Perceptual Audio coding" by Jorg Houpert in Studio-Technik or the article "Daten-Diat, Datenreduktion bei digitalisierten Audio-Signalen" by Stefanie Renner in Elrad, 1991. These overview articles as well as the PCT A-document WO 88/01811 are explicitly referred to with regard to the explanation of any terms and process steps not made more apparent herein.
In a number of cases, it is necessary to transmit signals from several signal sources simultaneously via a corresponding number of transmission channels. The transmission of stereo signals via two transmission channels is mentioned as the most simple example therefor.
The transmission of signals from N signal sources via a corresponding number of transmission channels presents the problem of dimensioning the transmission channels:
If each individual transmission channel is dimensioned in such a manner that it transmits the "maximum incident bit flow", comparatively large transmission capacity remains unused "on the average".
In the transmission of signals from numerous signal sources via a corresponding number of transmission channels, it is known from digital telephone technology to design the transmission channels for only "average demand" and to balance short-term increased demand on individual channels by allotment from other channels. The allotment ensues exclusively via signal statistics.
For the state of the art, reference is made to the following literary sources "Ein digitales Sprachinterpolationsverfahren mitpradiktlonsgesteuerter Wortaufteilung" by Dr. H. Gerhauser (1980), "Ein digitales Sprachinterpolationsverfahren mit momentaner Prioritatszuteilung", by R. Woltowitc (1977) and "Ein digitales Sprachinterpolationsverfahren mit blockweiser Prioritatszutellung" by G. G. Klahnenbucher (1978).
An element of the present invention is that it was understood that the usual processes in digital telephone technology for balancing fluctuating demand in the transmission of numerous signals via a corresponding number of transmission channels does not have good results if the digital signals to be transmitted previously underwent data reduction, by way of illustration, according to the so-called OCF process.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a process for simultaneous transmission of signals from N signal sources via a corresponding number of transmission channels with which "data-reduced signals" can be transmitted via transmission channels that are only dimensioned for "average demand" without any perceptible, i.e. by way of illustration audible, loss in signal capacity.
The present invention is based on the fundamental idea not to conduct the allotment to the individual signals according to statistical considerations in balancing the fluctuating requirements during simultaneous transmission of signals from N signal sources via a corresponding number of transmission channels, but rather already to balance the fluctuating demand by appropriate means in the process step in which the signals are coded for data reduction.
BRIEF DESCRIPTION OF THE DRAWINGS
This inventive fundamental idea is explained in the following, using a preferred embodiment with reference to the accompanying drawings, in which:
FIG. 1 is a block diagram to explain the invented process, and
FIGS. 2a and 2b depict the invented signal build-up
In the invented process the individual signals are divided into blocks, and the blocks are transformed into spectral coefficients by tran
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patent: 5216503 (1993-06-01), Paik et al.
patent: 5309232 (1994-05-01), Hartung et al.
Kou et al, "Digital Speech Interpolation for Variable Rate Coders with Apcation to Subband Coding", Oct. 1985, pp. 1100-1108.
Waal et al., "Subband Coding of Stereophonic Digital Audio Signals", 1991, pp. 3601-3604.
Hang et al, "Digital HDTV Compression Using Parallel Motion-Compensated Transform Coders", Jun. 1991, pp. 210-221.
Taka, "Low-Bit-Rate Speech Codecs and Wideband Speech Codecs", Jan. 1988, pp. 49-55.
Brandenburg Karl-Heinz
Gerhauser Heinz
Seitzer Dieter
Sporer Thomas
Fraunhofer Gesellschaft zur Forderung der angewandten Forschung
Marcelo Melvin
Vu Huy D.
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