Multiplex communications – Communication techniques for information carried in plural... – Transmission bandwidth conservation
Reexamination Certificate
1997-08-29
2001-01-23
Vo, Huy D. (Department: 2735)
Multiplex communications
Communication techniques for information carried in plural...
Transmission bandwidth conservation
C370S351000, C370S357000, C370S359000, C370S468000
Reexamination Certificate
active
06178182
ABSTRACT:
BACKGROUND OF THE INVENTION
Communication networks for switching and transmitting digitized voice information are usually formed by a plurality of communication systems partially connected to, or respectively meshed with one another and to which communication terminal equipment is connected. The call setup and the call control ensues with signaling information. The digitized voice information is communicated between the communication systems in message channels and the signaling information is communicated in a signaling channel of a multiplexed message stream. The digitized voice information usually exhibits a bit rate of 64 or 56 Kbit/s and the multiplexed message stream exhibits bit rates of n×64 Kbit/s (for example, 2048 Kbit/s), whereby the message streams between the communication systems are transmitted over non-switched transmission paths.
In order to more efficiently use the transmission paths and the transmission equipment arranged between the communication systems, compression devices allocated to the transmission equipment and are used to compress the digitized voice information (for example, to form a compressed voice information with 16 Kbit/s and then multiplexed to form a message stream of, for example, 2048 Kbit/s). The multiplexed message stream is demultiplexed and the compressed voice information is decompressed at a communication system receiving such a message stream. Given a connection to a destination communication terminal equipment of this destination communication system as may be set up by the signaling information, the decompressed voice information is further communicated to the respective destination communication terminal equipment.
German Published Application DE 44 23 792 A1, for example, discloses a circuit arrangement for multiple utilization of basic channels in ISDN. The total data bit rate of 64 Kbit/s, available in a basic channel of an ISDN connection for data transmission, is divided time-offset with a suitable converter onto a plurality of data-reduced or, respectively, compressed, voice-coded, multiplexed speech channels having a lower bit rate.
When the respective communication system, according to the connection that has been setup, represents a transit communication system, then the respective, decompressed voice information is switched connection-conforming and is subsequently compressed again, inserted into a message stream or, respectively, multiplexed and communicated to the further communication system in conformity with the connection. The decompressing and compressing in the transit communication system causes time delays and distortions of the voice information that lead to a deterioration in the quality of the communicated, digitized voice information.
SUMMARY OF THE INVENTION
It is an object of the present invention to reduce the quality losses in the transmission of compressed voice information.
An important aspect of the inventive method is that a voice information compressed in an originating communication system that is to be transmitted via a plurality of communication systems, is not switched decompressed but compressed in the transit communication systems. As a result thereof, an additional time delay and a distortion of the communicated voice information is entirely avoided. In addition, the decompression and compression means can be at least partially foregone. Multiplexed devices that can be advantageously and economically realized are provided for the matching of the compressed voice information to the switching bit rate.
According to an advantageous embodiment of the present invention, compression information, indicating the compression, is communicated between the communication systems together with at least one compressed voice information. Advantageously, the compression information for at least two compressed voice information are communicated in one message channel of the message stream. Thus, given compressed voice information with 16 Kbit/s via 2×64 Kbit/s message streams (for example via an ISDN connection between two communication systems), compressed voice information are transmitted over seven message channels and the compression information for the seven message channels provided for the communication of compressed voice information are transmitted in the eighth message channel. During the call setup, the remote communication system is respectively informed by a communicated compression information as to whether and in what message channel a compressed voice information is being communicated.
Advantageously, the compressed voice information and compression information are multiplexed to form message streams of 56 or, respectively, 64 Kbit/s or m×56 or, respectively, 64 Kbit/s. The message streams are conducted over non-switched, individual 64 Kbit/s connections or over a non-switched ISDN—SO connection (2×64 Kbit/s) or an ISDN—S
2
primary connection (32×64 Kbit/s).
The compression of the digitized voice information with 56 or 64 Kbit/s advantageously ensues in 2
n
steps (n=2, 4, 8, 16). Referred to message channels with 64 Kbit/s, a compression of the voice information with 16 Kbit/s according to the standardized compression method according to G.728 is especially advantageous since the voice quality remains very high given a considerable savings of transmission paths and transmission equipment resources. The compressed voice information, advantageously 16 Kbit/s, is inserted into an information stream with the switching bit rate of 64 Kbit/s for the switching in a transit communication system.
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Blitz Andre
Rott Walter
Wille Klaus
Phan M.
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
Vo Huy D.
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