Multiplex communications – Data flow congestion prevention or control
Reexamination Certificate
1998-05-07
2001-02-20
Hsu, Alpus H. (Department: 2738)
Multiplex communications
Data flow congestion prevention or control
C370S328000, C370S375000, C370S524000, C370S538000
Reexamination Certificate
active
06192030
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a communication system between at least one CS concentrator connected to at least one PHS radio base station (hereinafter referred to as CS) and located in a remote area and a subscriber terminal device in a PHS exchange.
In a conventional PHS system, connection is made by a 1.5M primary-group transmission line between a CS concentrator containing a plurality of CSs and having a line concentrating function and a subscriber terminal device in a PHS exchange. The 1.5M primary-group transmission line is, as disclosed in Bellcore TR-TSY-000303, a system for time division multiplexing of (2B+D) channels of an ISDN basic interface (hereinafter referred to as BRI) on time slots and for multiplexing a maintenance channel C in a channel D time slot.
Also, as disclosed in TTC JT-Q931-b, it is well known that there is a mode having an interface structure for a shared channel D. In this case, a certain BRI channel is used as a control channel of a channel B in another BRI. The mode has the interface structure of (16B+D) which uses eight BRIs.
Further, as a traffic control method of the conventional PHS exchange, the following procedure is known. In the procedure, in response to a calling/position registration message which is generated beyond a processing capability and defined by TTC JT-Q931-b, a disconnection message is returned from the exchange back to the CS concentrator.
The aforementioned 1.5M primary-group transmission line is not an economical loop operation method. This is because in the system using the conventional 1.5M primary-group transmission line, the call control of sixteen channels B in eight BRIs is performed by a channel D of a single BRI and seven channels D are therefore unused.
Also, in the conventional traffic control method, in response to the calling/position registration message, the disconnection message is returned from the exchange back to the CS concentrator. In this case, when the number of CS concentrators is increased, there is a possibility that not only a new calling/position registration but also a call in the midst of a call setting procedure are disconnected by time out of a timer (T
310
) of layer
3
because of a delay between the CS concentrators and the exchange and a delay inside the exchange. Specifically, in the conventional traffic control method, when the number of CS concentrators is increased and the call information beyond the processing capability is received, then the information is placed in a queue for processing. Therefore, the more the quantity of call information is, the longer the waiting time in the queue is.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a PHS subscriber loop multiplex communication system in which by multiplexing two (14B+D) channel call control groups in a 2M primary-group transmission line, a line operation efficiency is enhanced.
Another object of the present invention is to provide a simple PHS subscriber loop multiplex communication system which obviates the necessity of changing a (16B+D) interface structure in conformity to TTC JT-Q931-b as a layer
3
function of a CS concentrator using a conventional 1.5M primary-group transmission line and a subscriber terminal device.
Still another object of the present invention is to provide a PHS subscriber loop multiplex communication system in which even when an excess load is applied, a predetermined processing capability can be realized through a traffic control using a maintenance control information channel (channel C) which is different from a call control information channel (channel D) and multiplexed in the same time slot as that of the channel D.
To attain this and other objects, the present invention provides a PHS subscriber loop multiplex communication system in which connection is made by a 2M primary-group transmission line between a PHS radio base station concentrator connected to a PHS radio base station and located in a remote area and a subscriber terminal device in a PHS exchange, and two (14B+D+C) channel call control groups are multiplexed on the 2M primary-group transmission line.
According to an aspect of the present invention, a PHS radio base station concentrator includes a first interface section for interfacing with a subscriber terminal device via a 2M primary-group transmission line in which two (14B+D+C) channel call control groups are multiplexed on a single transmission line; a first (D+C) channel terminal section for terminating a channel D for performing communication with the subscriber terminal device by using TTC JT-Q921-b and a channel C for receiving maintenance control information from the subscriber terminal device; and a first time division multiplex switch section for using a time division switch to connect (D+C) channel information of the first (D+C) channel terminal section to a (D+C) channel interfacing on the 2M primary-group transmission line. The subscriber terminal device includes a second interface section for interfacing with a PHS radio base station terminal device via the 2M primary-group transmission line in which two (14B+D+C) channel call control groups are multiplexed on a single transmission line; a second (D+C) channel terminal section for terminating the channel D for performing communication with a PHS radio base station by using TTC JT-Q921-b and the channel C for transmitting the maintenance control information to the PHS radio base station; and a second time division multiplex switch section for using a time division switch to connect (D+C) channel information of the second (D+C) channel terminal section to the (D+C) channel interfacing on the 2M primary-group transmission line. In the 2M primary-group transmission line, two groups of (14B+D+C) channels are placed.
REFERENCES:
patent: 5283788 (1994-02-01), Morita et al.
patent: 5761274 (1998-06-01), Uehara et al.
patent: 5835484 (1998-11-01), Yamato et al.
patent: 6047176 (2000-04-01), Sakamoto et al.
Foley & Lardner
Ho Duc
Hsu Alpus H.
NEC Corporation
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