Telecommunications – Radiotelephone system – Auxiliary data signaling
Reexamination Certificate
1998-12-01
2002-04-09
Legree, Tracy (Department: 2681)
Telecommunications
Radiotelephone system
Auxiliary data signaling
C455S426100, C455S433000, C455S445000, C455S448000
Reexamination Certificate
active
06370390
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to delivery of short messages to mobile stations and particularly to delivery of short messages in mobility-supporting packet radio networks that use a mobile communications network as an access network, to a dual-mode mobile station in a situation where the mobile station is not reachable in the packet radio network.
Mobile communications systems have been developed because there has been a need to free people to move away from fixed telephone terminals without impairing their availability. Simultaneously with the increase in the use of various data transfer services at offices, various data services have also been introduced in mobile communications systems. Lap-top computers make efficient data processing possible everywhere the user moves. Mobile communications networks offer to the user an efficient access network for mobile data transfer, thus providing access to the actual data networks. For this purpose, various new forms of data service for the present and future mobile networks are being planned. Digital mobile communications systems, such as the pan-European mobile communications system GSM (Global System for Mobile Communications), support mobile data transfer particularly well.
The General Packet Radio Service GPRS is a new service in the GSM system, and it is one of the topics of GSM Phase 2+standardization work at ETSI (European Telecommunications Standards Institute). The GPRS operating environment comprises one or more subnetwork service areas that are interconnected by a GPRS backbone network. The subnetwork comprises a number of packet data service nodes SN, termed serving GPRS support nodes (SGSN) herein, each being connected to a GSM mobile communications network (typically base station systems) so as to be able to offer a packet data service to mobile data terminal equipment via several base stations, i.e. cells. The intermediary mobile communications network offers packet-switched data transfer between the support node and the mobile data terminals. The different subnetworks for their part are connected to an external data network, e.g. a public switched data network PSPDN, via specific GPRS gateway support nodes GGSN. Hence, the GPRS service allows packet data transfer between mobile data terminals and external data networks, the GSM network serving as an access network. The GPRS network architecture is illustrated in FIG.
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One kind of service of mobile communications networks is short message service (SMS). This differs from voice and data services in that to send a short message, no connection from the sending party to the receiving party need to be established, as the short messages are transmitted in the form of signalling messages. Data transfer by means of short messages is limited to one message only. Short message services are asymmetric, and the transmission of a mobile-originated short message is considered a different service from the transmission of a mobile-terminated short message. In a GSM network, short messages can be received and sent even during an ongoing call, as short messages are relayed on control channels. A short message service center SM-SC is an entity delivering short messages and storing and retransmitting short messages the delivery of which has failed. All short messages pass through a short message service center SM-SC. A short message service center can receive a short message through any network for delivery to a mobile station MS. The short message service center SM-SC transfers the short message it received to a gateway mobile switching center for short message service (SMS-GMSC) for further delivery to a mobile station. An incoming short message from a mobile station is transmitted via an interworking mobile switching center for short message service (SMS-IWMSC) to a short message service center for further delivery. To provide short message service, a GPRS network has a serving GPRS support node SGSN connected to a gateway mobile switching center for short message service, SMS-GMSC, and to an interworking mobile switching center for short message service, SMS-IWMSC. Through these, a mobile station MS attached to a GPRS network can send and receive short messages on the radio channels of the GPRS.
The mobility management (MM) activities related to a GPRS subscriber are characterized by one three different MM states of the mobile station MS: Idle State, Standby State, and Ready State. Each state describes a certain level of functionality and information allocated to the mobile station MS and to the serving GPRS support node SGSN. The information sets relating to these states, which are maintained in the serving GPRS support node SGSN and in the mobile station MS, are denoted MM contexts. The context of the serving GPRS support node SGSN comprises subscriber data, such as the subscriber IMSI, TLLI, and location or routing data, etc.
In the idle state, the mobile station MS is not reachable from the point of view of the GPRS network, and the network holds no current state, location, or routing information for the mobile station MS, i.e. no MM context. If the mobile station MS is of dual mode, i.e. is capable of operating in GPRS and GSM networks, it may be in the GSM network when being in GPRS-Idle state. The mobile station MS can move from idle state to ready state by attach to the GPRS network, and from standby state or ready state to idle state by detach from the GPRS network.
In the standby and ready states, the mobile station MS is attached to the GPRS network. The ready state is the actual data transfer state in which the MS is capable of transmitting and receiving user data. The MS passes from standby state to ready state either when the GPRS network pages the mobile station or when the mobile station MS starts data transfer or signalling. The mobile station MS may remain in the ready state (for a time-out preset in a timer) even when no user data is transferred or no signalling takes place. If the mobile station is a ‘dual mode’ mobile station and is in standby state or ready state, the paging required by circuit-switched services, e.g. a voice call to be made to the mobile station, is made through the serving support node SGSN of the GPRS network. In other words, the GSM paging is carried out as GPRS paging.
When a short message service center SM-SC receives a short message SM for delivery to a mobile station MS, the short message service center forwards it to a gateway mobile switching center for short message service, SMS-GMSC, which examines the destination MS address and requests routing information from the relevant home location register HLR. The home location register HLR of the GSM network also contains the GPRS subscriber data and routing information. The home location register HLR sends in its message the serving GPRS support node (SGSN) address of the mobile station MS or the VLR address at the mobile services switching center MSC, or both. If the HLR message contains only the MSC/VLR address, the short message is delivered normally through the GSM network. If the HLR message contains an SGSN address, the gateway mobile switching center for short message service, SMS-GMSC, forwards the short message SM to the serving GPRS support node SGSN. If the mobile station MS is attached to the network and is reachable, the serving GPRS support node SGSN transfers the short message SM to the mobile station MS.
However, the serving support node SGSN may not be able to deliver the short message SM to the mobile station MS on account of for instance the fact that the radio channel conditions are poor or the mobile station MS is detached from the GPRS network, i.e. is in idle state. The HLR is not aware of the state of the mobile station, it only knows the addresses. When the serving support node SGSN does not succeed in delivering the short message to the mobile station, the serving support node SGSN sets a flag MSNRF (=Mobile Subscriber Not Reachable Flag) indicating that the mobile station is not reachable, and sends a failure report to
Haumont Serge
Salin Hannu-Pekka
Altera Law Group LLC
Legree Tracy
Nokia Telecommunications Oy
Persino Ray
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