Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-07-09
2001-02-06
Eisenzopf, Reinhard J. (Department: 2745)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S456500
Reexamination Certificate
active
06185421
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Invention
The present invention relates generally to a telecommunications system, apparatus and method for paging mobile terminals within a cellular network, and specifically to optimizing use of paging channels by dividing location areas into sub-location areas and providing a more flexible and efficient method of paging mobile subscribers.
2. Background and Objects of the Present Invention
Cellular telecommunications is one of the fastest growing and most demanding telecommunications applications ever. Today it represents a large and continuously increasing percentage of all new telephone subscriptions around the world. A standardization group, European Telecommunications Standards Institute (ETSI), was established in 1982 to formulate the specifications for the Global System for Mobile Communication (GSM) digital mobile cellular radio system.
With reference now to
FIG. 1
of the drawings, there is illustrated a GSM 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 Services 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 MS
20
may also include a Subscriber Identity Module (SIM) card
13
, or other memory, which provides storage of subscriber related information, such as a subscriber authentication key, temporary network data, and service related data (e.g. language preference).
The MSC
14
is in communication with at least one Base Station Controller (BSC)
23
, which, in turn, is in contact with at least one Base Transceiver Station (BTS)
24
. The BTS
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. It should be understood that the BSC
23
may be connected to several base transceiver stations
24
, and may be implemented as a stand-alone node or integrated with the MSC
14
. In either event, the BSC
23
and BTS
24
components, as a whole, are generally referred to as a Base Station System (BSS)
25
.
With further reference to
FIG. 1
, the PLNN 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, International Mobile Subscriber Identity (IMSI) numbers, 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 Mobile Stations
20
currently located within the MSC/VLR area
12
. If an MS
20
roams into a new MSC/VLR area
12
, the MSC
14
will request data about that Mobile Station
20
from the HLR database
26
(simultaneously informing the HLR
26
about the current location of the MS
20
) and store the data in the VLR
16
connected to that MSC
14
. 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
.
The radio interface is the general name of the connection between the MS
20
and the BTS
24
, which utilizes timeslots (TS) within each allocated frequency to transmit speech, data and control signaling, with each TS being referred to as a physical channel. Different types of information, e.g., speech, user data and control signaling, must be transmitted on these physical channels through the use of logical channels, which are mapped onto the physical channels. The logical channels can be divided into two groups: control channels and traffic channels. Speech is sent on the traffic channels, while user data and control signaling are transmitted on control channels.
One type of control channel is a paging channel (PCH) to which the MS
20
listens to see if the network
10
wants to get in contact with the MS
20
. For example, the network
10
may wish to get in contact with the MS
20
because the network
10
is receiving an incoming call or a Short Message Service (SMS) message for the MS
20
. The information on a PCH is a paging message, which includes the MS's identity number. The paging message is transmitted to the MS
20
on the downlink (from the BTS
24
to the MS
20
), as a broadcast message.
The paging channels are a valuable network resource, and thus, optimization of their use will lead to better network frequency utilization and traffic throughput. With the increase in traffic, such as point-to-point SMS messages, the paging capacity is likely to become a bottleneck in the system.
When a subscriber moves from one LA
18
to another, a procedure called Location Update is performed to inform the network
10
where to page the MS
20
in case of an incoming call or message. In general, the smaller the LA
18
, the more Location Updates are generated by MS's
20
moving between LA's
18
. However, if the LA
18
is large, which corresponds to a large number of cells
22
, when a mobile terminating call comes into the network
10
, the called subscriber (MS
20
) is paged within the entire LA
18
, which includes every cell
22
in the LA
18
. Therefore, each BTS
24
within each cell
22
sends a paging message on a separate PCH.
Thus, the larger the LA
18
, the more network resources (paging channels) are used to page a MS
20
within the LA
18
. In sum, there is a trade-off between paging efficiency (most efficient when the LA
18
is small) and the Location Update load (most efficient when the LA
18
is large). However, the size of the LA
18
is typically configured for an average subscriber, while in reality, there are some subscribers, such as business subscribers, who use the MS
20
heavily. For these heavy-use subscribers, a smaller LA
18
is preferred, because these subscribers are paged frequently. In addition, there are also some subscribers who only use the MS
20
for emergencies. For these light-use subscribers, a large LA
18
is preferred, because the paging activity is minimal. Existing technology has not provided a way to maximize network resources (paging channels) based upon the subscriber usage.
It is, therefore, an object of the present invention to optimize the use of paging channels based upon the usage characteristics for subscribers within the network.
SUMMARY OF THE INVENTION
The present invention is directed to a telecommunications system, apparatus and method for optimizing the use of paging channels within the network by dividing location areas (LAs) into sub-location areas (sub-LAs) and providing a more flexible and efficient method of paging mobile subscribers. The amount of usage of the paging channels and the number of location updates performed by a mobile subscriber can be monitored by the network to determine either a ratio of the number of pages to the number of location updates, or a subscriber category associated with the mobile subscriber. The ratio or subscriber category, e.g., heavy-user or light-user and high-mobility or low-mobility, can be stored within the Subscriber Identity Module (SIM) card within the mobile terminal. Alternatively
Alperovich Vladimir
Borg Gunnar
Bhattacharya Sam
Eisenzopf Reinhard J.
Ericsson Inc.
Jenkens & Gilchrist P.C.
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