Location update protocol

Details Location update protocol Location update protocol

2000-12-14

2004-10-26

Appiah, Charles (Department: 2686)

Telecommunications

Radiotelephone system

Zoned or cellular telephone system

C455S456100, C455S435100, C455S436000, C711S130000, C711S141000, C711S119000

Reexamination Certificate

active

06810259

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to mobile communications networks, and more specifically to a location update protocol for use in managing subscriber profile information associated with each of a plurality of mobile hosts of the network as the hosts move from one location in the network to another in a mobile communications network.
2. Description of the Prior Art
FIG. 1
shows a generalized block diagram of a conventional wireless mobile communications network at
10
, the network
10
being operated in accordance with a prior art fully centralized cache management system for managing subscriber profile information associated with each of a plurality of subscribers of the network. The network
10
includes a central database system
14
(also commonly referred to as a network operating center, or an operations support system (OSS)) having a central server computer system
16
, and a central database
18
communicatively coupled with the central server
16
. The central database
18
provides a centralized cache for storing subscriber profiles associated with each of the subscribers, each profile including all information necessary for executing call-processing operations associated with the subscriber. The central database also provides for storing location register information associated with subscribers of the network, the location register information typically including a home location register database (HLR database) for storing location information associated with local registered subscribers of the network, and a visitor's location register database (VLR database) for storing location information associated with roaming users of the network. When location information associated with a particular subscriber is required (e.g., for executing call processing functions), the central database system
14
is called upon to perform lookup functions in order to determine a profile and a current location of the subscriber in the network, the central database system then provides the location information along with the profile associated with the particular subscriber as further explained below. Typically, the central database system
14
is supported by a back office system that includes a subscriber management system, a billing system, and a network management system (not shown). Wireless communications networks, such as the network
10
, typically operate in accordance with one of the wireless cellular communications standards such as GSM, CDMA, etc.
The wireless mobile network
10
further includes a plurality of base stations
24
communicatively coupled with each other, with the central database system
14
, and with the transaction servers
20
via the backbone
22
of the network. Typically, each of the base stations
24
is communicatively coupled with a radio port (not shown) having an antenna
26
, and is operative to communicate via wireless links with each of a plurality of mobile hosts
30
located within a coverage area
28
associated with the base station. Each of the mobile hosts
30
may be a cellular telephone handset, a personal digital assistant (PDA), or a lap top computer having wireless communication capabilities. As examples, a first one of the base stations
24
designated BASE_STATION_
1
is associated with a first coverage area designated AREA_
1
, and a second one of the base stations designated BASE_STATION_
2
is associated with a second coverage area designated AREA_
2
.
FIG. 2
shows a table diagram illustrating a global subscriber list at
40
including subscriber profile information associated with each subscriber of the network
10
, the global subscriber list
40
being stored in the centralized database
18
(
FIG. 1
) of the central database system
14
, and being managed in accordance with the prior art fully centralized data management system. The global subscriber list
40
includes a plurality of subscriber profile cache entries
42
each being associated with one of the subscribers of the network
10
(FIG.
1
), and having: a subscriber key field
44
for storing a subscriber key value associated with one of the subscribers of the network; a base station location field
46
for storing a node identification value indicating an associated owner one of the base stations
24
(
FIG. 1
) which currently “owns” the associated subscriber profile as further explained below; and a profile information field
50
for storing the actual profile data associated with the subscriber.
Referring back to
FIG. 1
, when a subscriber initially activates one of the mobile hosts
30
within one of the coverage areas
28
, a registration procedure is performed for “signing on” to the network. In accordance with the registration procedure, the host
30
transmits an associated link layer identifier (ID) to the local base station. The link layer ID typically includes a manufacturer identification value, which uniquely identifies the subscriber's host device. When the base station receives the link layer ID, the base station must initially query the central database system
14
by sending a registration message to the central database system via one of the transaction servers
20
requesting access to a subscriber profile associated with the host. Typically, the network addresses of the transaction servers
20
are configured into the base stations
24
. The registration message carries the link layer ID of the host, and the current location of the host which is indicated by the node ID value of the owner base station. The central server
14
is responsive to the registration message, and is operative to retrieve a subscriber profile matching the link layer ID from the central database
18
, and is also operative to update the location field
46
(
FIG. 2
) of the corresponding subscriber profile cache entry to indicate the current location of the associated host in the event that the location has changed since a last transaction. So, the location of each subscriber is assumed to be the particular base station, which detected the sign-on, and the current owner of the profile is that particular base station.
In order to be able to correctly process calls to and from each of the mobile hosts
30
in the mobile communications network
10
, a mechanism is provided to keep track of the location of subscribers. The location field
46
(
FIG. 2
) of each subscriber profile must be updated as the mobile hosts move within the network. As one of the hosts
30
moves from one of the coverage areas
28
to another, a handoff procedure is performed to transfer ownership of the associated subscriber profile (as well as control of communication between the host and other nodes of the network) from an old one of the base stations
24
to a new one of the base stations
24
. Each of the base stations is operative to generate location update messages upon each hand-off that occurs, and is operative to provide the location update messages to the central server
16
for updating associated subscriber profiles. Each of the location update messages indicates a transfer of ownership of an associated one of the subscriber profiles.
In accordance with call processing operations in a fully centralized cache management system, when a call is initiated from a first one of the hosts
30
(a calling party) to a second one of the hosts (a called party), the base station currently associated with the calling party sends a query message to the central database
18
, requesting profile and location information associated with the called party. The central database system
14
is responsive to the query messages, and operative to provide the requested profile information and location information to the base station associated with the calling party.
As an example of a call processing function, a calling party using HOST_A, currently located in AREA_
1
, initiates a call to a called party using a second host designated HOST_B that is currently located in AREA_
2
. BASE_STATION_
1
which covers AREA_
1
must determine a pro

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