Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
2000-04-18
2004-06-08
Pham, Chi (Department: 2663)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S469000
Reexamination Certificate
active
06747989
ABSTRACT:
TECHNOLOGICAL FIELD
The invention concerns generally the use of certain protocols and services for conveying certain types of information between the different nodes of a telecommunication network. Especially the invention concerns the transmission of multimedia-related information between a terminal of a cellular radio network and a store-and-forward type messaging center which has a network connection to at least one node computer of a fixed packet-switched network.
BACKGROUND OF THE INVENTION
Multimedia is generally understood as the synchronized presentation of audiovisual objects to a user. It is typical to multimedia-related information that it may contain elements of highly different nature, like text, still images, simple graphical elements, video and sound.
MMS or Multimedia Messaging Service is a proposed way for arranging the delivery of messages containing multimedia-related information from one telecommunication device to another. With “multimedia-related” information we mean both the actual payload data that represents presentable objects and the control information that tells a presentation device how to handle the payload data. According to the proposals, MMS should be applicable for conveying such messages to and from the terminals of packet-switched cellular radio networks such as GPRS (General Packet Radio Service) and the packet-switched parts of UMTS (Universal Mobile Telecommunication System) in a store-and-forward manner much like the SMS (Short Messaging Service) text messages are conveyed in the second generation digital cellular networks, e.g. GSM (Global System for Mobile telecommunications).
FIG. 1
illustrates some system aspects of a known proposal for arranging the transmission of MMS messages between two mobile terminals
101
and
102
. In
FIG. 1
each terminal is operating in a cellular telephone system of its own: terminal
101
is a UMTS terminal operating in a UMTS network
103
and terminal
102
is an enhanced GSM terminal operating in an enhanced GSM network
104
. From both networks there is a connection to a GPRS network
105
. The UMTS network
103
comprises a UTRAN or UMTS Terrestrial Radio Access Network
106
as well as a CN or Core Network
107
. In the enhanced GSM network
104
a BSS or Base Station Subsystem
108
and an MSC or a Mobile Switching Centre
109
are shown. The detailed structure of the network elements is unessential to the present invention, but it is known that for example a UTRAN consists of a number of Radio Network Subsystems, each of which in turn comprises a Radio Network Controller and a number of Node Bs roughly corresponding to base stations. A BSS in turn comprises a Base Station Controller and a number of Base Transceiver Stations operating under it. Various mixed-mode cellular telephone systems are possible; for example the BSS
108
might operate under the same CN as the UTRAN
106
. The terminals could also be exactly similar terminals operating close to each other in a single cell.
In
FIG. 1
there is a connection both from the UTRAN
106
and from the BSS
108
to a corresponding SGSN or Serving GPRS Support Node
110
and
111
. Both of these are in turn coupled, through the GPRS trunk lines, to a GGSN or Gateway GPRS Support Node
112
which also operates as an MMSC or a Multimedia Messaging Service Center. In analogy with the known SMS arrangements a terminal
101
may transmit an MMS message by identifying both the intended recipient's terminal
102
and the MMSC through which the message is to be transmitted (actually the latter may even be left out if there is a default MMSC for each terminal). A Packet Control Unit or a corresponding functionality in the UTRAN
106
takes the MMS transmission and routes it through the current SGSN
110
to the MMSC
112
which stores the MMS message and commences the attempts for delivering it to the intended recipient. If there is an existing connection to the recipient's terminal
102
the MMSC may deliver the message through the corresponding SGSN
111
and the BSS
108
to the terminal
102
. If, however, the terminal
102
is temporarily shut off, out of coverage or otherwise unreachable, the MMSC retries the delivery at certain time intervals until either the message is successfully delivered or a timeout expires indicating that the message is obsolete and can be deleted undelivered. A positive or negative acknowledgement, depending on the success in delivery, may be returned to the transmitting terminal
101
if required.
A topic for discussion has been the most advantageous way of using the lower-level protocol layers and PDP Contexts (Packet Data Protocol) in the terminals and fixed network devices to convey the MMS messages. Somewhere at a relatively high level in the protocol stacks of both the terminals and the MMSC there must be an MMS-TP (Multimedia Messaging Service—Transport Protocol) entity that uses the services offered by the lower level protocols to convey an MMS message first from the transmitting device to the MMSC and then further to the receiving device. Additionally the MMS messages must be mapped into PDP Contexts of certain type; the mapping will be closely related to the choice of lower protocol layers under the MMS-TP entity. We anticipate that network operators will require the MMS messaging to be distinguishable from other forms of packet-switched data transmission in order to arrange for a suitable charging scheme for the MMS services.
At least three prior art solutions have been proposed for conveying MMS messages. One of them is to have a PDP Type separately defined for MMS, and to set up a PDP Context of that type between a terminal and an MMSC each time an MMS message has to be conveyed in either direction. This approach has the drawback of requiring a considerable amount of completely new specification and standardization work. Additionally new PDP Types are only very reluctantly accepted to the already frozen standards. A second proposed prior art approach is to build the MMS messaging on top of the known IP or Internet Protocol PDP Type. The latter approach would require the GGSNs to reserve and allocate dynamic IP addresses to mobile users. The use of dynamic addresses is not efficiently combined to MMS services, and in any case using the IP PDP Type for MMS messaging would consume the scarce IP addresses and involve the whole complexity of allocating and maintaining IP addresses and dynamically configuring hosts. A terminal roaming in another network should in practice always use the MMSC of its home network, because there is no possibility of dynamically telling the IP addresses of other MMSCs to the terminal.
A third approach has been proposed in the Finnish patent application no. 990586 of the same applicant, which application is not available to the public at the time of filing this application. The third approach is based on the use of the OSP or Octet Stream Protocol as the supporting lower-level service for the multimedia-related information. The advantages of OSP comprise limited overhead information, avoidance of dynamic IP address allocation, minimal need for revision to existing specifications and flexible addition of future enhancements. However, it has been found out that even the use of OSP does not solve all problems related to the arrangement of FIG.
1
: the implementation of the integrated GGSN/MMSC entity is quite complex, and the multimedia messaging service must be directly controlled by the operator responsible for the operation and maintenance of the fixed packet-switched network.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a feasible method and a corresponding arrangement for conveying MMS messages between terminals and MMSCs. It is an additional object of the invention that the proposed method does not require exhaustive respecification in the framework of existing standards and proposals. A further object of the invention is to minimize the required protocol overhead in the MMS traffic between the terminals and the MMSCs. An even further object
Ferris Derrick W.
Pham Chi
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