Telecommunications – Radiotelephone system – Usage measurement
Reexamination Certificate
1998-12-30
2001-07-03
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Usage measurement
C455S423000, C455S424000, C455S008000, C455S009000, C455S067150, C455S067700, C379S111000, C379S001040, C379S026020, C379S016000, C379S022000
Reexamination Certificate
active
06256490
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Invention
The present invention relates generally to telecommunications systems and methods for generating alarms due to base station failure, and specifically to providing a cell traffic supervision alarm.
2. Background and Objects of the Present Invention
Mobile communications, especially cellular radio, is one of the fastest growing and most demanding telecommunications applications ever. Today it accommodates a large and continuously increasing percentage of all new telephone subscriptions around the world with the increasing service requirements. Cellular networks have evolved into two different networks within Time Division Multiple Access (TDMA) technology. The European cellular network uses the Global System for Mobile Communication (GSM) standard as the digital cellular system. In the United States, cellular networks have traditionally been primarily analog, but recent advances have been incorporating digital systems within the analog networks. One such North American cellular network is the D-AMPS network, which is described hereinbelow.
With reference now to
FIG. 1
of the drawings, there is illustrated a D-AMPS Public Land Mobile Network (PLMN), such as cellular network
10
, which in turn is composed of a plurality of areas
12
, each with a Mobile Switching Center (MSC)
14
and an integrated Visitor Location Register (VLR)
16
therein. The MSC/VLR areas
12
, in turn, include a plurality of Location Areas (LA)
18
, which are defined as that part of a given MSC/VLR area
12
in which a mobile station (MS)
20
may move freely without having to send update location information to the MSC/VLR area
12
that controls the LA
18
.
Each Location Area
12
is divided into a number of cells
22
. Mobile Station (MS)
20
is the physical equipment, e.g., a car phone or other portable phone, used by mobile subscribers to communicate with the cellular network
10
, each other, and users outside the subscribed network, both wireline and wireless. The MSC
14
is in communication with a Base Station (BS)
24
. The BS
24
is the physical equipment, illustrated for simplicity as a radio tower, that provides radio coverage to the geographical part of the cell
22
for which it is responsible.
With further reference to
FIG. 1
, the PLMN Service Area or cellular network
10
includes a Home Location Register (HLR)
26
, which is a database maintaining all subscriber information, e.g., user profiles, current location information, and other administrative information. The HLR
26
may be co-located with a given MSC
14
, integrated with the MSC
14
, or alternatively can service multiple MSCs
14
, the latter of which is illustrated in FIG.
1
.
The VLR
16
is a database containing information about all of the MS's
20
currently located within the MSC/VLR area
12
. If an MS
20
roams into a new MSC/VLR area
12
, the VLR
16
connected to that MSC
14
will request data about that MS
20
from the HLR database
26
(simultaneously informing the HLR
26
about the current location of the MS
20
). Accordingly, if the user of the MS
20
then wants to make a call, the local VLR
16
will have the requisite identification information without having to reinterrogate the HLR
26
. In the aforedescribed manner, the VLR and HLR databases
16
and
26
, respectively, contain various subscriber information associated with a given MS
20
.
If a failure occurs in a BS
24
, in many cases, the BS
24
will be unable to handle any traffic. Loss of service at a cell
22
means a loss of revenue to the network operator as well as an inability by mobile subscribers to place calls. The inability of mobile subscribers to place calls can cause dire consequences, especially if one or more of the calls is an emergency call.
Currently, there are specially-designed alarms in place in BS's
24
to detect specific hardware or software conditions. However, there are certain conditions under which a BS
24
will be unable to handle any traffic, but yet there is no alarm transmitted to the MSC
14
. Causes for this may include, but are not limited to, normal degeneration or vandalism of certain key cables inside the BS
24
which may not have alarm supervision. In this situation, routine checks of the BS
24
might uncover the problem, or an operator at the MSC
14
might notice that there has been no traffic on the BS
24
for an unreasonable period of time. However, especially in the case of remote BS's
24
, such routine checks may be infrequent. Alternatively, the condition might come to the attention of the operator if a user complains about lack of service.
All of the above solutions are inadequate to protect against potentially lengthy periods of time during which service in a cell
22
is unavailable, which can cause, among other things, as stated hereinbefore, increased customer dissatisfaction and loss of revenue for the operator. In addition, as mention above, loss of service even for a small period of time could also result in serious consequences if an emergency call is necessary but not possible.
It is, therefore, an object of the present invention to provide an alarm that is triggered by lack of normal traffic at a cell site.
It is a further object of the present invention that the alarm automatically adjusts itself based upon the normal traffic load at the cell site.
SUMMARY OF THE INVENTION
The present invention is directed to telecommunications systems and methods for providing a cell traffic supervision alarm to notify the operator at the MSC if a BS has had no traffic for a period of time that is unreasonably long. The definition of “unreasonably long” is tied to normal traffic patterns at the BS. An alarm threshold time, which is defined as time between the cessation of all traffic on a BS and the triggering of the alarm, can be calculated based upon a statistical analysis of the traffic history of the BS to determine a time interval such that the probability is acceptably small (as defined by the network operator) that under normal conditions the BS would have gone for that entire length of time with no traffic at all. At the expiration of the alarm threshold time, the alarm is triggered. The alarm threshold time is preferably as short as possible, while also maintaining the probability of a false alarm at a level that is low enough to be acceptable to the operator.
REFERENCES:
patent: 5241534 (1993-08-01), Omuro et al.
patent: 5285494 (1994-02-01), Sprecher et al.
patent: 5790955 (1998-08-01), Tomoike
patent: 5872911 (1999-02-01), Berg
patent: 5913162 (1999-06-01), Gourdin et al.
Panchapakesan Shankari
Shahdad Yunis
Yost George P.
Ericsson Inc.
Ferguson Keith
Jenkens & Gilchrist P.C.
Trost William
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