Telecommunications – Wireless distribution system – Two-way
Reexamination Certificate
1998-10-13
2001-04-17
Trost, William G. (Department: 2746)
Telecommunications
Wireless distribution system
Two-way
C455S509000, C455S560000
Reexamination Certificate
active
06219525
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an access network system that is connected to an existing local switch, includes a base station connected through a wireless circuit with fixed terminals such as user terminals installed in subscriber's houses, and is employed as an access network like a WLL (wireless local loop) with a function of concentrating user channels. Here, the access network refers to a network that connects the local switch of a caller with a called user, excluding the local switch and the user terminal themselves.
2. Description of Related Art
FIG. 7
is a block diagram showing a configuration of a conventional access network like a WLL. In
FIG. 7
, the reference numeral
1
designates a WAC (WLL Access Controller) which is the controller of a WLL; and
2
designates a base station that is connected with the WAC
1
through a trunk line
5
. The reference numerals
3
a
-
3
b
each designate user equipment connected with the base station
2
through a wireless circuit
4
; and the reference numeral
6
designates a service node including the local switch. The reference numerals
7
each designate a subscriber line connecting the WAC
1
with the service node
6
;
8
a
-
8
b
each designate a user terminal connected to the user equipment; and the reference numeral
9
designates a service node interface installed in the WAC
1
for interfacing the WAC
1
to the service node
6
. This configuration shows an example in which the subscriber lines
7
use analog lines.
Next, the operation of the conventional access network will be described with reference to
FIG. 8
, a sequence diagram illustrating the operation of the conventional access network as shown in
FIG. 7
, when a call request takes place from the service node
6
but the base station
2
detects a channel busy state in the access network.
First, the service node
6
issues a ringing (call request) to the WAC
1
, and switches the state of the current subscriber line
7
connecting the service node
6
with the WAC
1
into an incoming call state. Receiving the ringing from the service node
6
, the WAC
1
transmits a paging message to the all of the base stations
2
. When each of the user equipment
3
accepts the paging from the service node
6
through the base station
2
, it sends a link channel setup request back to the base station
2
to request a setup of a wireless channel. Receiving the link channel setup request from the user equipment
3
, the base station
2
checks whether any idle channel is present in the wireless circuit
4
. If the base station
2
cannot detect any idle channel in the wireless circuit
4
, it sends back to the user equipment
3
a link channel assignment rejection response indicative of being unable to setup a wireless channel.
Even if the base station
2
detects an idle channel afterward, it cannot complete the incoming call to user equipment
3
because the base station
2
does not include any means for carrying out the call processing again. In the course of time, in response to the abandonment of the call by an originating terminal, the service node
6
switches the subscriber line
7
from the incoming call state to a normal state, and stops the paging signal. Detecting the halt of the paging signal by the service node
6
, the WAC
1
releases the paging.
With such an arrangement, the conventional access network system cannot complete the call to the user equipment
3
, when the service node
6
makes a call request, but the wireless circuit
4
between the base station
2
and the called user equipment
3
is busy (no idle channel is present in the wireless circuit
4
), or the trunk line
5
between the WAC
1
and the base station
2
is busy. In addition, even if the base station
2
detects an idle channel afterward, it cannot complete the calling processing again, in spite of the incoming call state of the current subscriber line
7
of the service node
6
, because the base station
2
does not comprise any means for carrying out the call processing subsequently. This presents a problem of increasing call loss.
SUMMARY OF THE INVENTION
The present invention is implemented to solve the foregoing problem. It is therefore an object of the present invention to provide an access network system that can reduce the probability of the loss of a call made by the service node during a busy state of the trunk line or wireless circuit in the access network.
According to a first aspect of the present invention, there is provided an access network system comprising: a controller of an access network, which is connected to a local switch through subscriber lines, and has a concentrating function of the lines; a base station that is included in the access network, and is connected to the controller; and at least one user equipment that is connected to the base station through a wireless circuit, and is connected to a user terminal, wherein the base station comprises: first notification means for notifying the controller of an absence of an idle wireless channel when no available channel is present in the wireless circuit between the user equipment and the base station at a time when the local switch makes a call request to the user terminal; monitor means for detecting an idle wireless channel in the wireless circuit; and second notification means for notifying the controller of a presence of an idle wireless channel when the monitor means detects an idle wireless channel, and wherein the controller comprises: call processing reserving means for reserving a call processing of the call request when the absence of the idle wireless channel is notified; and call processing means for releasing, when the presence of the idle wireless channel is notified, the reservation of the call processing, and for carrying out a call processing to the user equipment through the base station, when the call request still continues.
According to a second aspect of the present invention, there is provided an access network system comprising: a controller of an access network, which is connected to a local switch through subscriber lines, and has a concentrating function of the lines; a base station that is included in the access network, and is connected to the controller; and at least one user equipment that is connected to the base station through a wireless circuit, and is connected to a user terminal, wherein the base station comprises: notification means for notifying the controller of an absence of an idle wireless channel when no available channel is present in the wireless circuit between the user equipment and the base station at a time when the local switch makes a call request to the user terminal, and wherein the controller comprises: call processing reserving means for reserving a call processing of the call request when the absence of the idle wireless channel is notified by the notification means; a timer for counting a predetermined timer value; call processing means for starting the timer at a beginning of a reservation of the call processing, for releasing, when the timer completes counting of the predetermined timer value, the reservation of the call processing, and for carrying out the call processing to the user equipment through the base station, when the call request still continues; and timer restart means for restarting the timer with reserving the call processing of the call request a second time when the absence of the idle wireless channel is notified again.
According to a third aspect of the present invention, there is provided an access network system comprising: a controller of an access network, which is connected to a local switch through subscriber lines, and has a concentrating function of the lines; a base station that is included in the access network, and is connected to the controller; and at least one user equipment that is connected to the base station through a wireless circuit, and is connected to a user terminal, wherein the base station comprises: first notification means for notifying the
Imai Takeshi
Matsuyama Hiroshi
Nemoto Masaaki
Jackson Blane J.
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
Trost William G.
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