Circuit switched data services for GSM

TECHNICAL FIELD

0001The present invention relates to a method at a telecommunications system for optimization of information transmission between a mobile subscriber and an interactive data service network.

PRIOR ART

0002At utilization of interactive data services, as for instance WWW on the packet based Internet, the data carrier is only utilized at times. Between longer or shorter data transmissions the user can make a pause to take care of for instance the information which he/she has collected, and the data carrier then is unemployed.

0003A problem is that the circuit switched and comparatively expensive service which GSM offers today is not optimal. Either the user pays for the time his/her communication is "silent", or he/she connects and disconnects the call according to need. The latter solution is very time-consuming because the user each time must authenticate himself/herself towards his/her Internet-server.

0004Another problem with present circuit switched applications is that if the GSM-mobile during a long file transmission which is going on disconnects the transmission, due to for instance poor radio channel, the whole received file is lost, whereby the file has to be transmitted again.

BRIEF DESCRIPTION OF THE INVENTION

0005The aim with the present invention consequently is to provide that this circuit switched GSM-service becomes both cheaper and better by solving above mentioned problems.

0006This aim is achieved by a method which is characterized in that a mobile user sets up a session towards an interactive service network, which session is active until the mobile user breaks the session, or one in a timer set time expires, and that said session is arranged superior to just any number of connections and disconnections on a digital channel between the mobile user and the interactive service network.

0007The advantage with a superior session in relation to connections and disconnections on the digital channel is that the session is active in spite of that the digital cahnnel is disconnected. When the mobile user again connects himself/herself towards the interactive service network for transmission of data information, he/she need not authenticate himself/herself which results in a very rapid establishment of connection.

0008Another advantage with the method according to the present invention is that the user or the application breaks the connection when no data information is wanted to be transmitted, and sets up the connection automatically when data information shall be transmitted. This results in that the mobile user only need to pay for the service during the time the data transmission is performed.

0009Further characteristics of the present invention are given in the subclaims.

0010The present invention now will be described more in detail with references to the enclosed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

0011Figure 1 shows schematically the in the communication system included units.

0012Figure 2 shows schematically a file which shall be transmitted divided into information blocks.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE PRESENT INVENTION

0013In Figure 1 the interactive service network consists of the packet based Internet 2. The mobile user 1 utilizes a GSM-terminal and the transmission of data information is made via the digital channel 3. The greatest advantage with an entire digital transmission 3 in comparison with a modem transmission is that the set up time can be reduced from about 20 to 5 seconds. This is today possible to perform by an Internet-server connected directly to an MSC/IWU (Mobile Switching Centre) or within a near future via ISDN to just any Internet-server (which supports ISDN).

0014The mobile user 1 sets up a session towards the Internet-server 2 in the same way as present applications by calling and authenticating himself/herself by means of a password and a user identity. This session then shall be active until the mobile user breaks the session or a timer (for instance the time during which no data is transmitted or received) expires. The session will after that be able to be superior to a large number of connections and disconnections on the GSM-channel. The user 1 or the application breaks the connection when no data is wanted to be transmitted, or establishes connection when data shall be transmitted and consequently makes use of the channel as efficiently as possible.

0015What has been described above results in that the mobile subscriber in principle only need to pay for the service when it is utilized, which makes it considerably more attractive than before. The advantage will be even more pronounced when HSCSD (High Speed Circuit Switched Data) will be introduced in about a year. This GSM-data service is based on that the subscriber can use and be debited for more time slots in order to increase the data rate.

0016One example of how the present invention can be utilized is ftp-transmission from a conventional ftp-server.

0017The mobile subscriber 1 sets up a UDI (entire digital) call towards his/her Internet-server 2 and authenticates himself/herself. The ftp-server in question is contacted by the application and one by the subscriber required file is collected.

0018When the transmission is finished, the subscriber 1 disconnects the call (for instance by means of a "close"-button in the application), or the call is disconnected by that a comparatively short time of a timer expires (time during which no data information has been transmitted).

0019The mobile subscriber 1 reads and processes his/her file but wants to read more files, so he/she orders home more files.

0020The application now sets up a data connection towards the server but this time authenticates itself only by means of the A-number and/or with automatic session code word which is executed automatically by the applications. This means that the subscriber 1 directly can proceed its Internet-session without any time-consuming authentication procedure.

0021When the subscriber 1 wants to finish the session, this is signalled on the data channel 3 and chain and session are broken, after which a new login procedure including password and user identity must be performed to again transmit data towards Internet.

0022Alternatively a timer expires and the session is broken.

0023A problem with present applications is, as has previously been mentioned, that if the GSM-mobile during a long file transmission which is going on, due to a poor radio channel disconnects the transmission 3, the entire amount of received data is lost and the file must be transmitted again in its entirety.

0024This problem is solved by the present invention by that the data information which is transmitted via the channel 3 is divided into numbered blocks as can be seen in Figure 1. A block number range 4 is valid for a whole session. Files which are transmitted via the channel 3 consequently are divided into n blocks 5, where each block includes on one hand data information 6 and on the other a block number 7. Between each block are provided just any number of filling bits 8 (bit stuffing) in order to separate two on each other following blocks.

0025Let us suppose that the mobile switching centre 2 (MSC/IWU) transmits file information to the mobile station 1 (MS) via the digital channel 3 according to the range of block numbers which is shown in Figure 2.

0026The mobile station 1 (MS) receives without problem the four first blocks whereupon the transmission 3 intentionally, or not intentionally, is broken. At a new connection trial MS transmits the block number of the last correctly received block, i.e. number 4, to the mobile switching centre (MSC/IWU). If the file transmission is not finished, the transmitting side 2 (MSC/IWU) now proceeds from where it finished, and consequently transmits the next block, i.e. block 5 etc.

0027With the present invention one will, accordingly, lose no information if a long file transmission which is going on for some reason is broken. The above mentioned protocol has similarities with the HDLC protocol family, but need not necessarily have error correction capacity.

0028What has been described above is only to be regarded as an advantageous embodiment of the present invention and the extent of protection of the invention is only defined by what has been indicated in the following patent claims.