Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-07-15
2001-05-15
Maung, Nay (Department: 2744)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C455S432300, C455S433000
Reexamination Certificate
active
06233457
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is directed to methods and to a mobile communication system for routing of call connections given respective calls directed to a radiotelephone subscriber who is registered at least in his home network regardless of the momentary location.
A cellular mobile communication system such as, for example, that according to the GSM standard (global system for mobile communication) is constructed of a plurality of radio cells and offers the radiotelephone subscriber a maximum of mobility in the framework of the radio communication. The country-overlapping international mobile communication system according to the GSM standard comprises a radio-oriented sub-system for the setup and cleardown and for maintaining radio connections between mobile stations and base stations, a switching-oriented sub-system for the setup, administration and cleardown of connections, taking mobility-specific functions into consideration, as well as an administration and maintenance sub-system for monitoring operating conditions and for controlling the network components arranged distributed in the system. Included among the tasks of the switching-oriented sub-system are the administration of the subscriber data of the radiotelephone subscribers, finding the location of a called radiotelephone subscriber or, respectively, mobile station at any arbitrary location of the GSM coverage area, the connection setup and cleardown as well as the acquisition of the charge dat (charging) for calls that depart from the radiotelephone subscriber or, respectively, arrive at the radiotelephone subscriber.
For implementing the tasks, the switching-oriented system has mobile switching centers available to it that, in particular, assume the mobility-conditioned methods and functions in the setup and cleardown of connections and in the call handling during a connection within the mobile radiotelephone network and at the interfaces to other communication networks, and also has visitor registers and home registers available to it, whereof the visitor register temporarily contains the subscriber data of the radiotelephone subscribers located at the moment in the coverage area of an allocated mobile switching center, whereas the subscriber data of the radiotelephone subscribers are permanently administered in the home register.
According to GSM Recommendation 03.79, Version 0.9.0 of Jul. 31, 1996—see, in particular,
FIG. 1
(architecture) and
FIG. 3
(flowchart) as well as chapters 9.2.2 and 9.2.4—, an optimized routing of call connections can be supported. When the mobile switching center (VMSCA) of a network receives a request to set up a signaling connection because of a call directed to a radiotelephone subscriber (B-subscriber), a message for the connection setup is sent to an access mobile switching center (GMSCA) of the network. According to the optimized routing, the access mobile switching center (GMSCA) has the possibility of directing a message for location inquiry to the home network (HPLMNB) of the called radiotelephone subscriber. The purpose of the location inquiry lies in requesting information—including a destination address—with reference whereto the access mobile switching center can decide whether a direct connection can be set up to a visitor mobile switching center that, for example, is currently responsible for the called radiotelephone subscriber due to the latter's location.
According to said GSM Recommendation 03.79, it is thereby necessary to separately assign a reference number (call reference number) for the identification of the call in the originating mobile switching center, to transmit this to the access mobile switching center and store it thereat. After a check was carried out to see, among other things, whether nothing opposes a direct connection to the visitor mobile switching center for reasons of charging, it is also necessary to start a separate message (note call destination) with the access mobile switching center in which the reference number is returned to the originating mobile switching center together with a destination address. The originating mobile switching center assigns the destination address to a call with the assistance of the reference number, stores the destination address for the charging and releases the reference number for re-assignment to another call. When a call redirection is set for the called radiotelephone subscriber, the access mobile switching center sends the separate message (note call destination) again with a new destination address deriving from the cal redirection. The signaling of the destination address ensues according to the mobile radiotelephone-specific user part (MAP) of the central signaling system CCS
7
and already begins with the arrival of the information offered by the home network that optimized routing can be implemented.
SUMMARY OF THE INVENTION
An object of the invention is to specify a method and a mobile communication system with which the signaling load given optimized routing of call connections can be reduced compared to the known method.
A lower switching-oriented signaling load between the switching center that receives a request for connection setup and an access mobile switching center that initiates optimized routing in inter-network fashion is achieved in that, after setup of a direct connection to a visitor mobile switching center, the access mobile switching center inserts a destination address offered by the home network of the called radiotelephone subscriber into a message that signals the creation of the call connection and returns this to the switching center in order to be interpreted thereat for charging the call connection. The assigning of a reference number by the switching center that must implement the charging and the transmission of the separate MAP message (note call destination) by the access mobile switching center are thus no longer necessary.
The insertion of the destination address into the message that informs about the creation of the call connection only after the setup of the call connection has an especially beneficial effect on the switching-oriented signaling outlay when a call redirection is set for the called radiotelephone subscriber. Due to the call redirection, the access mobile switching center—upon reception of a message that contains a new destination address—thereby sets up a connection to a switching center defined by the new destination address. Upon reception of the message that signals the creation of the call connection, the access mobile switching center inserts the new destination address into this message and returns it to the switching center that interprets it for charging the call connection. In this case, the signaling—differing from the known method—need not be implemented doubly between access mobile switching center and originating switching center, i.e. first due to the setup of the connection to the radiotelephone subscriber and subsequently due to the setup of the connection to the new destination defined by the call redirection, but only once, i.e. after the setup to the new destination due to the new destination address.
According to a development of the invention, the destination address in transmitted in an information field of the message that is provided for the entry of numerals. It is thereby advantageous when the destination address comprises at least one country code for the identification of the country in an inter-country cellular mobile radiotelephone network, and potentially additionally comprises a national code for the identification of the national network of the inter-country cellular mobile radiotelephone network.
It is advantageous when the call is initiated by a radiotelephone subscriber and the request for a connection setup is received by a mobile switching center of a mobile radiotelephone network. Alternatively thereto, the call can also be started by wire-bound network subscriber and the request for a connection setup can be received by a switching center of a wire-bound network.
It has proven benef
Hill & Simpson
Maung Nay
Siemens Aktiengesellschaft
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