Telecommunications – Radiotelephone system – Out-of-range indication
Reexamination Certificate
1998-12-30
2002-02-19
Bost, Dwayne (Department: 2681)
Telecommunications
Radiotelephone system
Out-of-range indication
C455S456500, C455S435100, C455S436000
Reexamination Certificate
active
06349206
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates in general to the field of telecommunications, and in particular, to providing to a user of a mobile terminal (MT) in a wireless network system a warning indication prior to disconnection when the MT moves into an invalid area.
2. Description of Related Art
Mobile wireless communication is becoming increasingly important for providing safety, convenience, improved productivity, and simple conversational pleasure to subscribers of wireless communications services. One prominent mobile wireless communication option is cellular communication. Cellular phones, for instance, can be found in cars, briefcases, purses, and even pockets. With the proliferation of cellular phone use, cellular phone subscribers are demanding increased coverage areas and the ability to use their cellular phones across different geographical areas, types of wireless networks, wireless network service providers, etc. Regardless of attempts to provide seamless and transparent wireless service, however, subscribers eventually transport their MTs from a position that provides service to them and for their particular MT to a position that does not for, e.g., technical, economic, or political reasons.
Referring now to
FIG. 1
of the drawings, an exemplary cellular wireless network, such as a Global System for Mobile Communication (GSM) Public Land Mobile Network (PLMN)
100
, will be described. The PLMN
100
is composed of a plurality of areas
105
, each with a Mobile Services Switching Center (MSC)
110
and an integrated Visitor Location Register (VLR)
115
therein. The MSC/VLR areas
105
, in turn, include a plurality of Location Areas (LA)
120
, which are defined as that part of a given MSC/VLR area
105
in which a Mobile Terminal (MT)
125
may move freely without having to send update location information to the MSC/VLR
110
that controls the LA
120
. Each LA
120
is divided into a number of cells
130
. The MT
125
is the physical equipment, e.g., a car phone, a computer with a wireless link, or other portable phone, used by mobile subscribers to communicate with the cellular network
100
, each other, and users outside the subscribed network, both wireline and wireless.
The MSC
110
is in communication with at least one Base Station Controller (BSC)
135
, which, in turn, is in contact with at least one Base Transceiver Station (BTS)
140
. The BTS
140
is the physical equipment, illustrated for simplicity as a radio tower, that provides radio coverage to the geographical part of the cell
130
for which it is responsible. It should be understood that the BSC
135
may be connected to several BTSs
140
, and may be implemented as a stand-alone node or integrated with the MSC
110
. In either event, the BSC
135
and the BTS
140
components, as a whole, are generally referred to as a Base Station System (BSS)
145
. It should be understood, however, that a BSS may alternatively be part of a satellite-based wireless network system.
With further reference to
FIG. 1
, the PLMN Service Area or wireless network
100
includes a Home Location Register (HLR)
150
, which is a database maintaining all subscriber information, e.g., user profiles, current location information, International Mobile Subscriber Identity (IMSI) numbers, and other administrative information. The HLR
150
may be co-located with a given MSC
110
, integrated with the MSC
110
, or alternatively can service multiple MSCs
110
, the latter of which is illustrated in FIG.
1
.
The VLR
115
is a database containing information about all of the MTs
125
currently located within the MSC/VLR area
105
. If an MT
125
roams into a new MSC/VLR area
105
, the VLR
115
connected to that MSC
110
will request data about that MT
125
from the HLR database
150
(simultaneously informing the HLR
150
about the current location of the MT
125
). Accordingly, if the user of the MT
125
then wants to make a call, the local VLR
115
will have the requisite identification information without having to reinterrogate the HLR
150
. In the aforedescribed manner, the VLR and HLR databases
115
and
150
, respectively, contain various subscriber information associated with a given MT
125
.
As explained hereinabove, while mobile service subscribers desire and often expect to use their MT
125
at whatever position they are entering, the LA
120
or the cell
130
that they are approaching or entering may be an invalid service area for them. Furthermore, even when subscribers suspect that they may be nearing the edge of their valid territory(ies), they are usually unaware of the exact geographical boundary between a territory in which they have service and one in which they do not. Consequently, wireless service subscribers that are in motion may be unexpectedly disconnected from their call without knowing why.
SUMMARY OF THE INVENTION
The deficiencies of the prior art are overcome by the method and system of the present invention. For example, as heretofore unrecognized, it would be beneficial if subscribers could be informed that they have traveled into an invalid area where their call will be disconnected. In fact, it would be beneficial if subscribers could be informed that they have traveled into an invalid area prior to call disconnection to thereby enable the subscribers to return their MT to a valid area or to gracefully complete the conversation of a current call.
A method and system enables a subscriber to be warned via an MT when the MT has moved into an invalid area during a call. The network monitors the location (e.g., position) of the MT during a call. When the MT enters a region (e.g., a cell) that is invalid because the region is part of an invalid area, the network sends a message to the MT. The message may be, for example, a novel cause code in a Direct Transfer Application Part (DTAP) message that triggers production of a warning action stored in the MT when the network does not have access to the transmission being sent to the MT. The message may alternatively be an announcement or tone sent directly to the MT when the network does have direct access to the transmission being sent to the MT. The network also begins a timer. If the MT is returned to a valid area before the timer expires, the call may be continued. Otherwise, the network may disconnect the call at the expiration of the timer.
In one embodiment, the valid and invalid areas are segregated by LAs and cells. A LA may have, for example, all valid cells or a mixture of valid cells and invalid cells. When the MT initiates a call set-up, a network element (e.g., an MSC) (or a combination of network elements) determines whether the current LA of the MT includes only valid cells. If so, the network element requests to be updated only when the MT enters a new LA. If not, the network element requests to be updated when the MT enters a new cell. Entry into each new cell prompts the network element to determine whether the new cell is valid or invalid.
If the MT enters an invalid cell during a call, the network element begins a warning process. A timer is started, and the MT is caused to provide a warning to the subscriber. The warning may be, for example, an announcement or tone stored in the MT that is triggered when the network element sends a code. Alternatively, when the transmission path includes the network element, an announcement machine may send an announcement or tone directly to the MT.
If the subscriber returns the MT to a valid cell before the timer expires, then the call may continue. If the timer expires first, the network element initiates a call disconnection procedure. Advantageously, in accordance with the present invention, not only is the subscriber informed as to why a call is being disconnected (e.g., MT presence in an invalid area) should the disconnection not be avoided, but the subscriber is also given an opportunity to avoid the disconnection by returning to a valid area and may be informed that the call disconnection process has been avoided af
Reichelt Martin
Shakil Nauman
Syed Inayat
Bost Dwayne
Ericsson INC
Jenkens & Gilchrist P.C.
West Z.
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