Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-11-16
2001-12-11
Bost, Dwayne (Department: 2681)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S432300, C455S458000
Reexamination Certificate
active
06330444
ABSTRACT:
BACKGROUND
The Global System for Mobile communication (GSM) is a radio communication system used by public land mobile networks (PLMNs) in many countries. The system is defined by a GSM standard that ensures uniformity and interoperability so that a user can access a GSM-compliant system anywhere in the world with minimal equipment compatibility problems. In addition to details such as modulation, frame formats, etc., the GSM standard specifies other activities that can be performed in the system. Many activities are associated with each particular subscriber, including call-related events such as call set-up and call termination. Other types of subscriber activities include invocation of call-related and call-independent supplementary services such as call hold, call waiting, call transfer, and call forwarding. Based on roaming agreements between different mobile network operators, a mobile subscriber belonging to a specific (home) PLMN (HPLMN) can use subscribed services and facilities while visiting (roaming in) other PLMNs (VPLMNs).
A network architecture typical of GSM systems is illustrated by
FIG. 1
, which shows an HPLMN
101
and VPLMNs
103
,
105
. In the HPLMN
101
, a home location register (HLR)
115
stores data relating to subscribers to that PLMN, including, for example, current location of the subscriber equipment, directory number (MSISDN), radio number plan identification (e.g., international mobile subscriber identity (IMSD)), supplementary service profiles and teleservice profiles. A mobile switching center (MSC) and visitor location register (VLR)
120
manage connections and data associated with subscribers who are currently situated within their area of responsibility, e.g., those subscribers to other PLMNs, such as the HPLMN
101
, who are roaming in their service area in the VPLMN
103
and their own subscribers belonging to the network operator that controls the VPLMN
103
. Although actually different nodes, the MSC and VLR are almost always co-located; thus, they are usually referred to as one MSC/VLR.
An authentication center (AUC)
125
works in close association with the HLR
115
, providing information for authenticating all communication sessions in order to guard against possible fraud, stolen subscriber cards, and unpaid bills. When a subscriber terminal
130
, such as a mobile telephone, that is a subscriber to the HPLMN
101
contacts a base station (BS)
135
and tries to register their presence while visiting PLMN
103
, the MSC/VLR
120
requests information from the HLR
115
in order to determine whether the terminal
130
is authorized to use the subscribed services and facilities within VPLMN
103
. The information is requested by the HLR
115
and stored therein, and the HLR
115
transmits the information to the MSC/VLR
120
in response to a request from the MSC/VLR
120
, e.g., during location updating. The MSC/VLR
120
transmits some of the information to the terminal
130
, which determines a response that it sends to the MSC/VLR
120
. Based on the response and the information, the MSC/VLR
120
determines whether the terminal
130
is authorized, and the HLR
115
updates its database to indicate that the terminal
130
is located in the area served by the MSC/VLR
120
.
When the terminal
130
moves from the VPLMN
103
to the VPLMN
105
, the terminal
130
recognizes the change and sends a location updating message to the new MSC/VLR (not shown) in the PLMN
105
. The new MSC/VLR informs the HLR
115
of the new location of the terminal
130
, and the HLR
115
sends a cancel-location message to the previously visited MSC/VLR
120
of the VPLMN
103
to indicate that the terminal
130
is no longer present in the area served by VPLMN
103
. The HLR
115
sends an insert-subscriber-data (ISD) message to the new MSC/VLR of the VPLMN
105
, providing the new MSC/VLR with the relevant subscriber data.
This architecture supports simultaneous activities in different MSC/VLRs in case of subscriber movement. In addition, activities on different gateway mobile switching centers (GMSCs) may be maintained simultaneously in various service scenarios. Typically, each PLNM has a GMSC, as indicated by GMSCs
140
,
145
in FIG.
1
. One scenario in which there are simultaneous subscriber activities is optimal routing, a network feature that enables calls to or attempts to initiate communication sessions with a subscriber to be routed directly to the subscriber's actual location or to the subscriber's forwarded-to destination. Without optimal routing, calls are routed via the HPLMN or, in the case of late call forwarding, via the VPLMN. In an exemplary optimal routing scenario, an HLR may receive send-routing-information (SRI) messages from other GMSCs that do not belong to the HPLMN network operator. An interrogating PLMN, which is the PLMN associated with an interrogating GMSC in an optimal routing scenario, interrogates the BPLMN of the called subscriber to determine the subscriber's location. The interested reader may refer to the GSM Technical Specifications (GTS) 02.79 and 03.79 for more details of the optimal routing feature.
Digital cellular communication systems such as those in accordance with the GSM standard have expanded functionality for optimizing system capacity and supporting hierarchical cell structures, i.e., structures of macrocells, microcells, picocells, etc. The term “macrocell” generally refers to a cell having a size comparable to the sizes of cells in a conventional cellular telephone system (e.g., a radius of at least about 1 kilometer), and the terms “microcell” and “picocell” generally refer to progressively smaller cells. For example, a microcell might cover a public indoor or outdoor area, e.g., a convention center or a busy street, and a picocell might cover an office corridor or a floor of a high-rise building. From a radio coverage perspective, macrocells, microcells, and picocells may be distinct from one another or may overlap one another to handle different traffic patterns or radio environments.
FIG. 2
illustrates an exemplary hierarchical, or multi-layered, cellular communication system that may be included in a PLMN. An umbrella macrocell
10
represented by a hexagonal shape makes up an overlying cellular structure. Each umbrella cell may contain an underlying microcell structure. The umbrella cell
10
includes microcell
20
represented by the area enclosed within the dotted line and microcell
30
represented by the area enclosed within the dashed line corresponding to areas along city streets, and picocells
40
,
50
, and
60
, which cover individual floors of a building. The intersection of the two city streets covered by the microcells
20
and
30
may be an area of dense traffic concentration, and thus might represent a hot spot.
FIG. 3
is a block diagram of the exemplary cellular communication system, including an exemplary mobile station (MS)
130
and base station (BS)
135
. The BS
135
includes a control and processing unit
150
which is connected through a base station controller (not shown) to an MSC/VLR
120
which in turn is connected to the public switched telephone network (PSTN)
155
(shown in FIG.
1
). General aspects of such cellular radiotelephone systems are known in the art. The BS
135
handles a plurality of voice and data channels through a channel transceiver
160
, which is controlled by the control and processing unit
150
. Also, each BS includes a control channel transceiver
165
, which may be capable of handling more than one control channel. The control channel transceiver
165
is controlled by the control and processing unit
150
. The control channel transceiver
165
broadcasts control information over a control channel of the BS or cell to MSs locked to that control channel. It will be understood that the transceivers
160
,
165
can be implemented as a single device, like the voice and control transceiver
170
, for use with control and traffic channels that share the same radio carrier.
The MS
130
receives the information broa
Hu Yun Chao
Rune Johan
Bost Dwayne
Burns Doane Swecker & Mathis L.L.P.
Gary Erika A.
Telefonaktiebolaget LM Ericsson (publ)
LandOfFree
Pre-page timer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pre-page timer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pre-page timer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2589994