Multiplex communications – Communication techniques for information carried in plural... – Assembly or disassembly of messages having address headers
Utility Patent
1998-06-09
2001-01-02
Olms, Douglas W. (Department: 2732)
Multiplex communications
Communication techniques for information carried in plural...
Assembly or disassembly of messages having address headers
C370S252000
Utility Patent
active
06169750
ABSTRACT:
This application is based on Patent Application No. 152,569/1997 filed on Jun. 10, 1997 in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a voice packet multiplexer that transmits to a network voices sent from a PBX (private branch exchange) after packet multiplexing them, and that transmits to the PBX voices obtained by receiving packet multiplexed voices from the network and disassembling them.
2. Description of the Related Art
Although the voice packet protocol is ruled in the ITU-T standard, the path control procedure between the voice packet multiplexers has not yet been determined. This presents some problems:
First, since a voice packet multiplexer, although connected to a PBX, is not provided with a routing function of packets, channels between the PBX and voice packet multiplexer must be connected with logical channels of a packet network on a one-to-one basis. Such a configuration is shown in
FIG. 1
, which illustrates that four channels extending from a PBX correspond to four logical channels of a packet network. Here, although the number of the logical channels of the packet network is shown by multiple lines in
FIG. 1
, they are actually only a single line physically.
The configuration as shown in
FIG. 1
must comprise between the PBX and voice packet multiplexer the same number of channels as that of logical channels between the office and party offices. The number of simultaneous use of the logical channels, however, is usually less than the total number of the logical channels because it is rare that all the offices use the logical channels at the same time, which must be taken into account when deciding the number of the channels of the PBX.
Thus, the conventional system has a drawback that more than necessary channels must be installed between the PBX and voice packet multiplexer, and this increases the cost.
Second, in the voice packet communication, time periods required for voice packets to be assembled by the voice packet multiplexer and transmitted to the next voice packet multiplexer through packet communication channels differ from packet to packet, which will be referred to as a “delay fluctuation” below. Accordingly, the voice packet multiplexer that receives the voice packets must cancel the delay fluctuations before reproducing the voices from them. To achieve this, it carries out such control that it once stores the voice packets in a memory, and adds delays to them before reproduction. This control will be called “delay fluctuation cancellation” from now on.
Furthermore, in the voice packet communication, the voices are compressed using a highly efficient encoding scheme when assembling the voice packets, and are expanded when disassembling the compressed voice packets. Repeating the compression and expansion through the highly efficient encoding scheme, however, will impair the fidelity of the reproduced voices as compared with the original voice, thereby degrading the articulation.
Third, the conventional voice packet multiplexers have a problem when they are employed in such a configuration as shown in
FIG. 2
, where an office A is connected with an office B through a leased line, the office B is connected with an office C through another leased line, and the voice packet multiplexers interconnect them.
When the office A communicates with the office C in such a system, a transit PBX is connected to the terminal side of the voice packet multiplexer in the office B, so that the transit PBX repeats the communication. Thus, in the configuration as shown in
FIG. 2
, the voice packet multiplexer in the office B carries out the delay fluctuation cancellation, while expanding the voice compressed through the highly efficient encoding scheme, sending it to the PBX and receiving it from the PBX, and compressing it again using the highly efficient encoding scheme, and then transmits it to the office C.
Such a configuration that passes the voice packets through the transit PBX has a problem of increasing the delay of the voice communication which demands the immediacy, because of the delay fluctuation cancellation carried out by the voice packet multiplexer connected to the transit PBX. Besides, an increasing number of compression and expansion processings using the highly efficient encoding scheme causes the reduction in the articulation of the reproduced voice.
Moreover, the transit PBX demands an additional cost for implementing the repeating function, and requires for transit channels to be assigned when determining the number of channels between the PBX and the voice packet multiplexer, which will prevent an efficient use of the PBX channels.
In view of this, a leased line interconnecting the offices A and C directly without passing through the office B can be installed to carry out communications between them. In this case, however, a problem arises of paying a charge for using the leased line.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a novel voice packet multiplexer for eliminating the foregoing problems involved in the conventional voice packet multiplexer.
In a first aspect of the present invention, there is provided a voice packet multiplexer which is connected with a PBX (private branch exchange), carries out packet multiplexing of voices and signals sent from the PBX to be sent to a packet communication channel, and disassembles a packet sent from a packet communication channel into voices and signals to be transmitted to the PBX, the voice packet multiplexer comprising:
digit detector for detecting digits in the signals sent from the PBX;
a logical channel retriever for retrieving a terminating logical channel according to the digits output from the digit detector;
a voice packet assembler for assembling a packet from the terminating logical channel and the voices sent from the PBX; and
a signal packet assembler for assembling a packet from the terminating logical channel and the signals sent from the PBX.
The present invention enables the efficient use of the channels of the PBX because it retrieves the logical channel from the digit information received from the PBX, and sets the retrieved logical channel in the address field of the voice packet when sending the signal packet or voice packet.
The voice packet multiplexer may further comprise:
a packet storage for storing the packet sent from the packet communication channel;
an originating logical channel detector for detecting an originating logical channel in a packet sent from an originating terminal; and
an address translator for translating, when transmitting the packet stored in the packet storage to the packet communication channel, an address field in the packet.
In this way, the present invention achieves a voice transit switching function that stores the originating logical channel of the calling terminal, which is retrieved from the received packet; retrieves the terminating logical channel of the called terminal by extracting the digit information; and translates, when transmitting the stored packet after the terminating logical channel has been established, the address field of the packet into the terminating logical channel if contains the originating logical channel, and the address field of the packet into the originating logical channel if it contains the terminal logical channel.
This makes it possible to reduce the delay time of the voice, increase the articulation of the reproduction voice, obviate the transit PBX, and remove the unnecessary logical channels between the voice packet multiplexers, thereby improving the speech quality and reducing the cost involved in installation and service.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of the embodiment thereof taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4611322 (1986-09-01), Larson
patent: 5379293 (1995-01-01), Kanno
patent: 5675574 (19
Aoki Makoto
Kii Junichi
Kokubun Shuhei
Sato Nobuki
Tomono Takamasa
Logic Corporation
Olms Douglas W.
Ostrolenk Faber Gerb & Soffen, LLP
Pizarro Ricardo M.
LandOfFree
Voice packet multiplexer with voice transit switching function does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Voice packet multiplexer with voice transit switching function, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Voice packet multiplexer with voice transit switching function will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2556563