Telecommunications – Radiotelephone system – Including personal numbering system
Reexamination Certificate
2001-01-12
2003-12-09
Trost, William (Department: 2684)
Telecommunications
Radiotelephone system
Including personal numbering system
C455S445000, C455S433000
Reexamination Certificate
active
06662017
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the routing of signaling messages in a communications network, and, more particularly, to methods and systems for processing and routing signaling messages associated with ported subscribers in a wireless communication network.
BACKGROUND ART
Within the global wireless telecommunications industry, the current trend in network technology is divided between global system for mobile communications (GSM) and ANSI-41 based architectures. In many respects, GSM and ANSI-41 based networks are quite similar, with the primary differences between the two technologies simply relating to the protocols used to communicate between the various network entities, and the operating frequencies of the communication handsets themselves. As such, in the interest of clarity, discussions of the present invention will henceforth be limited to GSM type network implementations. However, it should be appreciated that the present invention could be similarly practiced in an ANSI-41, Personal Communication Services (PCS) or similar type network.
A typical GSM network architecture is illustrated in FIG.
1
. As shown in
FIG. 1
, the typical GSM network, generally indicated by the numeral
100
, incorporates a number of functional elements or nodes which are appropriately interconnected so as to obtain the desired overall network service. These network nodes include a first mobile switching center
110
, a gateway mobile switching center
112
, a first home location register (HLR)
114
, a second home location register
116
, a visitor location register (VLR)
118
, and a second MSC
120
. Briefly, an HLR is a database that is used to store subscriber information for all customers within the home service area of the GSM service provider. Functionally, an HLR is linked through a signaling network to other service areas such that subscriber information may be efficiently shared between geographically diverse networks, a characteristic that facilitates seamless inter-network roaming. Like an HLR node, a VLR node is also a database that contains subscriber information. However, a VLR is specifically used to store information related to subscribers who are not in their home service area. More particularly, a VLR is where roaming related data for a customer is stored when the customer activates their handset outside of their designated home service area.
Again, the network elements described above (HLR and VLR) can be thought of as essentially databases or database processing nodes. Unlike these database nodes, MSCs and GMSCs are generally identified as network switching elements. Among their many functions, MSCs and GMSCs are responsible for determining which cell site will take possession of a call. Such hand off control is facilitated by a communication link between an MSC and an associated Base Station Controller (BSC)/Base Transceiver Station (BTS) pair (not shown). A GMSC node typically has the added distinction of providing connectivity to one or more HLR nodes; otherwise, MSC and GMSC functionality is very similar.
As generally illustrated in
FIG. 1
, GMSC
112
is coupled via signaling links to two HLR database nodes
114
and
116
described above, and as such, all signaling message access to these database nodes is controlled and administered by GMSC
112
. Of particular relevance to the present invention are the signaling aspects of the GSM network described above, especially those aspects associated with the signaling interactions between HLR, VLR and MSC or GMSC type nodes. A more detailed explanation of HLR, VLR and GMSC operation is provided below.
Within a GSM wireless communication network, each mobile station handset is assigned a unique identification number known as an International Mobile Subscriber Identity (IMSI) identification number. In the case of European GSM-type network implementations, the IMSI code is typically associated with a particular telephone handset. In such networks, each user can also be assigned one or more Mobile Station Integrated Services Digital Network (MSISDN) numbers. In the wireless telecommunications industry, MSISDN numbers are analogous to the 10 digit telephone numbers in a conventional North American wired network. The fact that multiple MSISDN numbers can be associated with a single IMSI number indicates that more than one MSISDN number can be assigned and used to reach a single mobile station handset. It should be appreciated that in this disclosure, the term “Mobile Identification Number” (MIN) is used generically to refer to IMSI, MSISDN, Mobile Global Title, ANSI-41 Mobile Identification Numbers (MIN) and Mobile Directory Numbers (MDN), and other identification numbers associated with subscribers or services in a wireless communication network.
In any event, an MSISDN number is dialed whenever a user wants to communicate with a particular mobile station handset. As indicated in
FIG. 1
, GMSC
112
, by analyzing a part of the dialed MSISDN number, determines the particular HLR that is storing routing information associated with the called mobile station. By retrieving and utilizing such routing information, the GSM network is able to locate the called mobile station in response to a call attempt so that a call connection can be established between the calling party and the called mobile station. It should also be appreciated that, depending on the nature of the call or signaling event, a GMSC may analyze and direct an HLR lookup based on either the IMSI or MSISDN number associated with the called or calling party.
In the particular example presented in
FIG. 1
, MSC
110
launches an ISDN user part (ISUP) initial address message (IAM) (message
1
) in an attempt to establish a call originated by a mobile subscriber that is being serviced by MSC
110
. Those skilled in the art of mobile communication networks will appreciate that an ISUP IAM message is one of many signaling messages that are employed in a signaling system 7 (SS7) based signaling network to facilitate the setup of a telephone call. A detailed discussion of SS7 signaling message types and their associated function can be found in
Signaling System #
7 by Travis Russell, McGraw-Hill Publishing 1998. Additionally, a detailed discussion of SS7 related signaling within a GSM network can be found in
The GSM System for Mobile Communications
by Michel Mouly and Marie-Bernadette Pautet, Cell & Sys 1992.
Returning to a discussion of
FIG. 1
, it will be appreciated that ISUP IAM message (
1
) is received by GMSC
112
, which in turn analyzes the message. More particularly, GMSC
112
examines the MSISDN value associated with the called party, as well as service indication information contained in the message. Shown in
FIG. 2
is a simplified routing database table
150
contained within GMSC
112
. This sample GMSC routing database table
150
is keyed or indexed based on a block or range of MSISDN numbers
152
. Associated with each block or range of MSISDN numbers is an address or identifier
154
of an associated HLR node.
Returning to
FIG. 1
, GMSC
112
performs a lookup in HLR routing table
150
, determines that this message should be delivered to HLR
114
, and subsequently formulates a send routing information (SRI) request message
2
. Upon receipt of SRI message
2
, HLR
114
examines the message and, in one case, determines that there is not enough information available to determine the appropriate routing address that is needed to deliver the original ISUP IAM message
1
to its destination. However, in such a scenario, HLR
114
is able to determine the routing address of a VLR
118
that contains the information necessary to continue the routing of ISUP IAM message
1
. This determination is made via a lookup in an internal routing database
156
, as shown in FIG.
2
. The simplified sample HLR routing database
156
is keyed or indexed by MSISDN number
158
and includes a pointer or address
160
to a VLR node that is currently servicing each MSISDN entry. Consequently, HLR
114
formulates a Provide Routing Number (PRN) m
Marsico Peter Joseph
McCann Thomas Matthew
Rao Raghavendra Gopala
West, Jr. Robert Fulton
Jenkins & Wilson & Taylor, P.A.
Sobutka Philip J.
Tekelec
Trost William
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