WO2002093945A2

WO2002093945A2 - Communication service provisioning method

Info

Publication number: WO2002093945A2
Application number: PCT/EP2002/005309
Authority: WO
Inventors: Rolf Hansson; Karsten Friese
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2001-05-14
Filing date: 2002-05-14
Publication date: 2002-11-21
Anticipated expiration: 2003-11-14
Also published as: JP4347576B2; JP2005508578A; AU2002344783A1; WO2002093966A1; WO2002093945A3

Abstract

Communication service provisioning method for provision of communication service in a first mode to a mobile communication means engaged in a communication session in a second mode different from the first mode, comprising the steps: - sending a paging message indicating an assignment of radio resources for a communication service in the first mode, - keeping the second mode communication session, - sending a communication message comprising payload to the mobile communication means by way of the assigned radio resources while the second mode communication session is kept, and - resuming the second mode communication session.

Description

Communication service provisioning method

The invention addresses the field of mobile telecommunications. The invention relates to a communication service provisioning method for provision of communication service in a first mode to a mobile communication means, and the invention relates to a communication service acceptance method for acceptance, at a mobile communication means, of a communication service in a first mode. Fur- thermore, the invention relates to a network node element of a cellular communication network, and the invention relates to a communication network. Finally, the invention relates to a computer program.

The above stated methods, network node element, communication network and computer program are known from a communication network conforming to the Packet Personal Digital Cellular (PPDC; sometimes called "Packet Pacific Digital Cellular") standard, also called RCR STD 27H standard. A Packet Personal Digital Cellular system can be an additional service to a mobile telephone system for circuit switched communication according to the Personal Digital Cellular (PDC; sometimes calls "Pacific Digital Cellular") standard.

Primary component of a circuit switched communication network according to the Personal Digital Cellular standard is a Mobile services Switching Center (MSC). The Mobile services Switching Center is responsible for the operation and main- tenance of the radio network resources. It provides functions for switching, call setup, circuit-switched charging, service provisioning and more. The Mobile services Switching Center also performs mobile station paging functions when it receives a voice call or a Short Message Service (SMS) message that is addressed to a mobile station. This applies as well if the mobile station is currently in packet state.

The packet data service according to the Packet Personal Digital Cellular standard enables end-users to access specific Internet-like content offered on an application server of a content provider and other Internet services by using a packet data mobile station as a connecting device. Data transfer from the application server to the mobile station is based on the Internet protocol.

The Packet Personal Digital Cellular system comprises at least one packet switching network node called packet mobile services switching center (PMSC). The packet mobile services switching center handles a packet data switching functionality, for example, between the application server and the mobile station. The packet mobile services switching center assigns Internet protocol addresses to the mobile station requesting a registration for an end-to-end packet data session to the application server and routes and forwards incoming and outgoing Internet protocol packets addressed to/from the registered mobile station. Functions provided by the packet mobile services switching center include registration and de- registration of the mobile station, authentication of mobile users, control of chan- nel reselection procedures, and update of routing information.

The RCR-STD 27H standard defines a packet data mode for Personal Digital Cellular mobile stations such as mobile phones. This standard also defines a paging for voice calls during packet data mode, i.e., while the mobile station is en- gaged in a packet data session.

When the mobile station engaged in packet data communication is notified of an incoming voice call or an incoming Short Message Services (SMS) message, the mobile subscriber can decide whether to accept or reject the incoming call. If the subscriber accepts the call, the mobile station starts to synchronize on the traffic channel. The Mobile services Switching Center then confirms the synchronization and sends an additional confirmation to the Packet Mobile services Switching Center. On receipt of this message, the Packet Mobile services Switching Center clears the existing packet data connection carried on the User Packet CHannel (UPCH) and provides its communication service to the mobile station via the cir- cuit switched connection over the traffic channel.

After establishment of the circuit switched connection, for example of a voice call, it is unclear if, when and how to return to the packet data mode. The circuit switched connection might last an unspecified time, therefore, the mobile station could occupy resources in the packet data node without using them, possibly for a long time. Additionally, the mobile station may have moved far away and recon- nection of a protocol stack is most likely impossible. Therefore, in case of acceptance of the first mode communication service, the second mode communication session is lost.

The problem underlying the present invention is to improve the known communication service provisioning method such that, at least on average, the disruptive impact on a second mode communication session is reduced.

According to a first aspect of the invention, the problem is solved by a communication service provisioning method for provision of communication service in a first mode to a mobile communication means engaged in a communication session in a second mode different from the first mode, comprising the steps: sending a paging message indicating an assignment of radio resources for a communication service in the first mode, keeping the second mode communication session, sending a communication message comprising payload to the mobile communication means by way of the assigned radio resources while the second mode communication session is kept, and - resuming the second mode communication session. The communication session in the second mode can be active or inactive. If the second mode session is active, data packets are transmitted between the network and the mobile station. If the second mode session is inactive, i. e. in packet standby, the mobile is ready for transmission of data packets between the network and the mobile communication means, in other words the mobile communication means is ready to send and/or to receive data packets. Assignment of radio resources particularly means that a radio channel for communication is assigned. Resuming the second mode session means that the mobile communication means returns to the second mode session which is thus continued.

The invention is advantageous because if the mobile communication means, being engaged in a second mode communication session, is offered a first mode communication service, as far as this service comprises delivery of a communication message to the mobile communication means, this first mode communication service can be accepted while the second mode communication session is kept, and subsequently the second mode communication session can be resumed. Thus, any disruptive impact of the acceptance of the first mode communication message on the second mode communication session is minimized.

Preferably, the paging message comprises an indication of a type of communication service that radio resources are assigned for, wherein the communication service type can be one of at least voice call type and communication message type. The paging message does not only indicate that a first mode communication service is offered but, in addition, according to the invention indicates the type of the offered first mode communication service, e.g., the type of a voice call or the type of a communication message such as a short message services (SMS) message or a multimedia message (MMS). The indication enables to distinguish between an incoming voice call and a communication message, in general allowing to decide how to handle the offer depending on whether it will be possible to re- turn to the second mode communication session once the offered communication service is accepted and concluded because the indicated communication service does not occupy resources for long. In particular, an automatic communication service acceptance method for acceptance of a communication message can be implemented. Thus, any disruptive impact of the acceptance of the first mode communication message on the second mode communication session is avoided.

Preferably, the paging message is provided as a voice paging message indicating the assignment of radio resources for sending the communication message. This way, a prior art standard paging message can be used for indicating the assignment of the radio resources. Thus, adoption of the inventive method is facilitated. Moreover, mobile communication means that are not adapted to operate according to the invention may still be used in a network adapted to operate according to the invention because using the standard paging message provides backwards- compatibility wherein the inventive system upgrade is optional and the inventive communication service type indication can be ignored.

In one embodiment, the step of keeping the second mode communication session comprises repeatedly performing the steps of attempting retransmission of data of the second mode communication session, to the mobile communication means, in the second mode, and waiting for a predetermined first interval of time, to receive a responsive transmission acknowledgement signal from the mobile communication means acknowledging reception of the retransmitted data of the second mode communication session, the steps being performed up to a predetermined number of retransmissions or until the transmission acknowledgment signal is received from the mobile communication means. In one embodiment, the step of keeping the second mode communication session comprises repeatedly performing the steps of attempting transmission of a request for reestablishment of the second mode communication session, to the mobile communication means, in the second mode, and waiting for a predetermined second interval of time, to receive a responsive reestablishment acknowledgement signal from the mobile communica- tion means acknowledging reception of the request for reestablishment of the second mode communication session, the steps being performed up to a predeter- mined number of transmissions or until the reestablishment acknowledgment signal is received from the mobile communication means. The communication provisioning method thus comprises a recovery method. According to this recovery method, retransmission of the data of the second mode communication session is attempted for up to a predetermined number of times; if no acknowledgement signal is received, resumption of the session is requested for up to a predetermined number of times.

According to a second aspect of the invention, a communication service accep- tance method is provided for acceptance, at a mobile communication means, of a communication service in a first mode, particularly for interaction with the inventive communication service provisioning method, the mobile communication means being engaged in a communication session in a second mode different from the first mode, comprising the steps: - receiving a paging message indicating an assignment of radio resources for communication service in the first mode, leaving said second mode communication session such that this session is resumable, receiving a communication message comprising payload information, and - reactivating said second mode communication session such that this session is resumed.

The step of resemble leaving the second mode communication session may comprise keeping data such as timer values, stacked data, or protocol context, as if the second mode communication session would not be actively interrupted by the mobile communication means. The invention is particularly advantageous because, instead of being disrupted, the second mode communication session is at worst only briefly interrupted due to the reception of the communication message such that the second mode communication session is - from the user's standpoint of view - smoothly continued throughout the reception of the communication message. In one embodiment, the paging message comprises an indication of a type of the communication service that radio resources are assigned for, wherein the type of the communication service can be one of at least voice call type and communica- tion message type. Preferably, the paging message is provided as a voice paging message indicating the assignment of radio resources for a communication service of the communication message type. This way, a standard paging message can be adapted for indicating the assignment of the radio resources. Thus, adoption of the inventive method is facilitated. The indication information enables the user to be informed about the indicated communication service type, and thus enables the user to decide whether to accept the communication service or not. Thus the user is able to decide whether to continue the second mode communication session or not.

In one embodiment, the inventive communication service acceptance method comprises the step of identifying the communication message by means of the communication service type indication comprised in the paging message, in order to perform, if the communication service type indication indicates a communication service of the communication message type, the steps of leaving the second mode communication session, receiving the communication message and reactivating the second mode communication session. This embodiment enables automatic acceptance of the offered communication service provided as the communication message such that the acceptance of the communication message fits particularly smoothly with the second mode communication session.

The step of leaving the second mode communication session comprises switching of the mobile communication means into the first mode. The step of reactivating the second mode communication session comprises switching of the mobile communication means into the second mode. Preferably, the step of reactivating the second mode communication session comprises receiving retransmitted data of the second mode communication session, and, in response to the data reception, sending an acknowledgement signal. Thus the resumption of the second mode communication session is indicated by the mobile communication means and the session can be resumed. Preferably, the step of reactivating the second mode communication session comprises receiving a request for reestablishment of the second mode communication session, and, in response to the request reception, sending an acknowledgement signal. Thus the readiness of the mobile communication means for a resumption of the second mode communication session is indicated such that the data of the second mode communication session thus far retransmitted in vain can now be successfully retransmitted.

In one embodiment, the first mode is provided as a circuit switched mode, the second mode is provided as a packet switched mode and the second mode communication session is provided as a packet data communication session. The communication message can be provided as a circuit switched message, e.g., as a short message services (SMS) message and/or as a multimedia service (MMS) message. During a voice call it would be inconvenient to keep the packet data communication session as the voice call can last for an unspecified time. Keeping the packet data communication session during the voice call would waste packet switched resources that were occupied but not used. However, as the circuit switched message has a short duration, keeping the packet data communication session during the delivery of the circuit switched message to the mobile communication means does not occupy unused resources for long.

Preferably, the paging message comprises a data field dedicated to operator spe- cific information, wherein the operator specific information field comprises said communication service type indication. The data field dedicated to operator specific information comprises an operator specific information element, said information element being formatted such that it comprises a first portion and at least a second portion, the first portion containing an operator specific information ele- ment length information, and the second portion containing the communication service type information to indicate that the payload, e.g., is a short message service (SMS) message.

According to a third aspect of the invention, a network node element is provided, in particular a second type switching means, of a cellular communication network, the network node element being adapted to perform the inventive communication service provisioning method.

According to a fourth aspect of the invention, a communication network is pro- vided comprising at least one inventive network node element. Furthermore, the network comprises a mobile communication means. The second type switching means is engaged in a second mode communication session with said mobile communication means. In one embodiment, the mobile communication network is provided as a Personal Digital Cellular (PDC) network, also called Pacific Digital Cellular network wherein the second mode mobile communication network capability is provided according to the Personal Pacific Digital Cellular (PPDC) standard, also called Packet Pacific Digital Cellular standard.

According to a fifth aspect of the invention, a mobile communication means is provided, the mobile communication means being adapted to perform the inventive communication acceptance method. The mobile communication means is located in a cellular communication network, in particular in a communication network as described above. The mobile communication means is contactable by a first type switching means of this cellular network. The mobile communication means can be engaged in a second mode communication session with a second type switching means of the cellular communication network. The mobile communication means is, e. g., provided as a mobile phone, as a personal digital assistant (PDA), or as a laptop computer adapted to communicate with the communication network. The mobile communication means is able to communicate in both, the first mode and the second mode. According to a sixth aspect of the invention, a computer program is provided that is loadable into an internal memory of a digital processing unit and that comprises software code portions adapted to control steps according to any of the inventive methods, particularly the inventive communication service provisioning method, when the computer program is executed on the digital processing unit. The computer program is comprised in a machine-readable medium. In one embodiment, the computer program is stored on a computer-readable medium such as a compact disc read only memory (CD-ROM), a floppy disc, an optical disc such as a digital versatile disc (DVD), or a hard disc. Thus a good portability of the control software is provided and upgrades can be performed in an easy way.

The invention can be used preferably in all communication systems as defined by the Third Generation Partnership Project (3GPP) in the release of 1999 as well as in all future release thereof and in Universal Mobile Telecommunications System (UMTS) networks. Furthermore, the invention can be used in Personal Digital Cellular (PDC) and Packet Personal Digital Cellular (PPDC) as well as Global Standard for Mobiles (GSM) networks, core networks including wireless local area access networks (WLAN), and the corresponding user equipment.

These and other aspects of the invention will be more fully understood by referring to the following detailed description and the accompanying drawings.

Fig. 1 shows a first inventive signaling sequence according to an embodiment of the inventive method wherein a resumption of a packet data session is per- formed while attempting retransmission of session data;

Fig. 2 shows a second inventive signaling sequence according to the embodiment of the inventive method in fig. 1 , wherein the resumption of the packet data session is performed while requesting session reestablishment after failure to retransmit session data; Figs. 3a, 3b and 3c show the format of a paging message according to the embodiment of the inventive method in figs. 1 and 2, wherein the paging message comprises a communication service type indication;

Figs. 4a and 4b show a first standard signaling sequence according to the embodiment in figs. 1 to 3, wherein the inventive paging signal is used;

Figs. 5a and 5b show a second standard signaling sequence according to the embodiment in figs. 1 to 3, wherein the inventive paging signal is used;

Figs. 6a, 6b, 7a and 7b show a third standard signaling sequence according to an alternative embodiment, wherein the inventive paging signal is used; and

Figs. 8a, 8b, 9a and 9b show a fourth standard signaling sequence according to the alternative embodiment in figs. 6 and 7, wherein the inventive paging signal is used.

Figs. 1 to 3 refer to a network NW conforming to a system according to the Packet Personal Digital Cellular (PPDC; sometimes called "Packet Pacific Digital Cellular") standard, also called RCR STD 27 standard, version H, of the Association of Radio Industries and Businesses (ARIB). The network NW comprises a Mobile services Switching Center MSC, not shown in the figures, responsible for the operation and maintenance of radio network resources. The Mobile services Switching Center MSC also performs mobile station paging functions when it receives a voice call or a Short Message Service (SMS) message that is addressed to a mobile station MS currently in packet state. Furthermore, the network NW comprises a Packet Mobile services Switching Center PMSC (not shown) for handling packet data. The Packet Mobile services Switching Center PMSC pro- vides a User Packet CHannel UPCH for usage during a packet data session to the mobile station MS. When the mobile station MS engaged in the packet data session is notified of an incoming voice call or an incoming Short Message Services (SMS) message, the mobile subscriber using the mobile station MS can decide whether to accept or to reject the incoming call. If the subscriber accepts the call, the mobile station MS starts to synchronize on a traffic channel TCH for circuit switched communication with the Mobile services Switching Center MSC. The Mobile services Switching Center MSC then confirms the synchronization and sends an additional confirmation to the Packet Mobile services Switching Center PMSC. On receipt of this message, the Packet Mobile services Switching Center PMSC clears the existing packet data connection carried on the User Packet CHannel (UPCH). The mobile station MS then starts with the circuit switched connection over the traffic channel TCH.

More particularly, when a circuit-switched call is received in the Mobile services Switching Center MSC while the mobile station MS is in packet state, the Mobile services Switching Center MSC sends a paging request to the Packet Mobile services Switching Center PMSC to obtain information about the cell that the mobile station MS is currently visiting. The Packet Mobile services Switching Center PMSC delivers the requested information by returning a paging response message to the Mobile services Switching Center MSC. According to the invention, the Mobile services Switching Center MSC determines weather the circuit-switched call is a voice call or a Short Message Services (SMS) message. In the latter case, the Mobile services Switching Center MSC assigns the traffic channel TCH and formats a UPCH (User Packet CHannel) Radio Channel Assignment signal, referred to as voice paging message URCA, which is forwarded through the Packet Mobile services Switching Center PMSC of the network NW to the mobile station MS. According to the invention, in this case, the User Packet CHannel (UPCH) used for packet data communication is maintained when the mobile station MS requests the Mobile services Switching Center MSC to establish the traffic channel TCH for Short Message Services (SMS) reception. After the Short Message Services (SMS) message has been received, the mobile station releases the traffic channel and returns to the User Packet CHannel (UPCH), thereby resuming the packet data communication.

The following parties are involved in the resumption mechanism: The mobile station MS has to read the paging type indicator. From this the mobile station MS can deduct whether the page is a voice call or a SMS delivery, i.e., the mobile station MS can differentiate between SMS and Voice pagings, and act accordingly. For example, to keep a packet data session and allow the mobile station to return to the packet data session the following mechanism is used: Rely on the Layer 2 (LAPDm) recovery mechanism, i.e., four retransmissions of data and four reestablishment tries. This gives the mobile station MS about sixteen seconds (two escalation levels * four retries * two seconds timeout = sixteen seconds). If the mobile station MS returns within this time, it can pick up the session where it left it. Thus, after completing the SMS reception, the mobile station returns to the original packet channel, and picks up the packet connection on layer 2 (LAPDm). Regarding the network, typically packet data calls are handled by different nodes than circuit switched calls. The packet data node has to include the paging type indicator in the paging message. The packet data node has to keep the packet ses- sion active and alive until Layer 2 (LAPDm) times out completely, even if the mobile station MS is reported to be receiving the SMS, to allow the mobile station MS to return. After time out, the packet session can be removed. The packet data node allows the packet session to resume where the mobile station MS left it before the paging of the mobile station. Thus, according to the invention, a packet data user does not lose packet data sessions, for example, due to short message service (SMS) message delivery. The packet data session is just shortly interrupted due to the message reception.

Referring now to figs. 1 and 2, the method is shown in detail by means of signal- ing sequences; in these sequences, positions of actions on the side of the network or on the side of the mobile station are referenced by encircled numbers. The sig- naling sequences evolve in time as indicated in figs. 1 and 2 by the time line t/sec running from top to bottom. In the case shown in figs. 1 and 2, the circuit- switched call is a Short Message Service (SMS) message.

In fig. 1, at (1) the network NW, more particularly the Packet Mobile services Switching Center PMSC, provides a voice paging message indicative of the imminent Short Message Service (SMS) message. The network NW sends the voice paging message using the User Packet CHannel UPCH to the mobile station MS where this paging message is received at (2). At (3) the mobile station MS leaves the User Packet CHannel UPCH and connects to a traffic channel TCH established between the mobile station MS and the Mobile services Switching Center MSC. At (5) the mobile station MS receives the Short Message Service (SMS) message sent from the network NW using the traffic channel TCH. At (8) the mobile station MS disconnects from the traffic channel TCH and returns to the User Packet CHannel UPCH.

Meanwhile on the side of the network NW, at (4) the Packet Mobile services Switching Center PMSC received packet data addressed to the mobile station MS. The Packet Mobile services Switching Center PMSC inserted the packet data into a packet data frame and attempted to send this frame to the mobile station on the User Packet CHannel UPCH. However, this attempt was futile and the frame was not delivered to the mobile station (indicated by an "X<-" in fig. 1) because the mobile station left the User Packet CHannel UPCH before, at (3). The Packet Mobile services Switching Center PMSC waits for a receipt acknowledgement from the mobile station MS until timeout is reached at (6). In the example shown in fig. 1, this timeout occurs two seconds after transmission of the frame was attempted at (4).

In order to keep the packet data session alive, the network uses the so-called Layer 2 (LAPDm) recovery mechanism which is as such described in the RCR-STD 27

H standard and that provides four data retransmissions and four session reestab- lishment tries. Data retransmissions and session reestablishment tries are each separated by two seconds. Altogether, from leaving the User Packet CHannel UPCH at (3), the mobile station thus has about 16 seconds to return to the User Packet CHannel UPCH, to respond to the network requests on this channel and thus to return to the packet communication session. This is usually sufficient for successful transmission of a short message services (SMS) message or a multimedia message (MMS).

Still at (6), the Packet Mobile services Switching Center PMSC requests resump- tion of the session by attempting retransmission of the data on the User Packet CHannel UPCH. However, this attempt is futile and the data are not delivered to the mobile station MS (indicated by an "X<-" in fig. 1) because the mobile station MS left the User Packet CHannel UPCH before, at (3). The Packet Mobile services Switching Center PMSC waits for a response from the mobile station MS until timeout is reached at (7). In the example shown in fig. 1, this timeout occurs two seconds after the retransmission of data was attempted at (6).

Still at (7), the Packet Mobile services Switching Center PMSC, again, requests resumption of the session by attempting retransmission of the data on the User Packet CHannel UPCH. However, this attempt is also futile and the data are not delivered to the mobile station (indicated by an "X -" in fig. 1) because the mobile station MS has still not returned to the User Packet CHannel UPCH. The Packet Mobile services Switching Center PMSC waits for a response from the mobile station MS until timeout is reached at (9). In the example shown in fig. 1, this timeout occurs two seconds after the retransmission of data was attempted at (7).

As explained above, at (8) the mobile station MS disconnects from the traffic channel TCH and returns to the User Packet CHannel UPCH. Now at (9), the Packet Mobile services Switching Center PMSC, for the fourth time, requests resumption of the session by attempting retransmission of the data on the User Packet CHannel UPCH. This attempt is successful and the data are delivered to the mobile station at (10) because the mobile station MS has returned to the User Packet CHannel UPCH. At (1 1), the mobile station MS sends a signal acknowledging of the reception of the retransmitted data to the Packet Mobile services Switching Center PMSC of network NW that receives this acknowledgement signal at (12) and the Packet Mobile services Switching Center PMSC stops the recovery mechanism and returns to its regular operation. Thus the packet data session is resumed by means of retransmission tries.

In fig. 2, like in fig. l, at (1) the network NW provides a voice paging message indicative of the imminent Short Message Services (SMS) message. The network NW sends the voice paging message using the voice paging message URCA to the mobile station MS where this paging message is received at (2). At (3) the mobile station MS leaves the User Packet CHannel UPCH and connects to a traf- fie channel TCH established between the mobile station and the Mobile services Switching Center MSC. At (5) the mobile station MS receives the Short Message Service (SMS) message sent from the network NW using the traffic channel TCH. At (18) the mobile station MS disconnects from the traffic channel TCH and returns to the User Packet CHannel UPCH.

Meanwhile on the side of the network NW, at (4), the Packet Mobile services Switching Center PMSC received packet data addressed to the mobile station MS. The Packet Mobile services Switching Center PMSC inserts the packet data into a frame and attempts to send this frame to the mobile station MS on the User Packet CHannel UPCH. However, this attempt is futile and the frame is not delivered to the mobile station (indicated by an "X<-" in fig. 2) because the mobile station left the User Packet CHannel UPCH before, at (3). The Packet Mobile services Switching Center PMSC waits for a response from the mobile station MS until timeout is reached at (6). In the example shown in fig. 2, this timeout occurs two seconds after transmission of the frame was attempted at (4). Still at (6), the Packet Mobile services Switching Center PMSC requests resumption of the session by attempting retransmission of the data on the User Packet CHannel UPCH. However, this attempt is futile and the data are not delivered to the mobile station (indicated by an "X -" in fig. 2) because the mobile station MS left the User Packet CHannel UPCH before, at (3). The Packet Mobile services Switching Center PMSC waits for a response from the mobile station MS until timeout is reached at (7). In the example shown in fig. 2, this timeout occurs two seconds after the retransmission of data was attempted at (6).

Still at (7), the Packet Mobile services Switching Center PMSC of network NW, again, requests resumption of the session by attempting retransmission of the data on the User Packet CHannel UPCH. However, this attempt is also futile and the data are not delivered to the mobile station (indicated by an "X<-" in fig. 2) because the mobile station has still not returned to the User Packet CHannel UPCH. The Packet Mobile services Switching Center PMSC waits for a response from the mobile station MS until timeout is reached at (16). In the example shown in fig. 2, this timeout occurs two seconds after the retransmission of data was attempted at (7). More futile retransmission attempts are undertaken at (16) and (17) so that altogether one transmission attempt at (4) and four retransmission attempts at (6), (7), (16) and (17) spaced by intervals of two seconds were undertaken without success.

As explained above, at (18) the mobile station MS disconnects from the traffic channel TCH and returns to the User Packet CHannel UPCH. Now at (19), the Packet Mobile services Switching Center PMSC, for the first time, requests resumption of the session by trying reestablishment of the packet data session on the User Packet CHannel UPCH. A reestablishment procedure is a preferred next step of an escalating two-step recovery mechanism that is based on a retransmission of data packets and a reestablishment of the whole packet data session. As the mo- bile station has returned to the User Packet CHannel UPCH the request for reestablishment is received at (20). At (21), in response to the request, the mobile sta- tion sends an acknowledgement of the receipt of the reestablishment request to the Packet Mobile services Switching Center PMSC that receives this acknowledgement at (22). Thus, after failure of four retransmission tries at (6), (7), (16) and (17), the packet data session is finally resumed at (22) by means of the reestab- lishment try at (19).

On receipt of the voice paging message URCA, the mobile station MS decides whether to discard the packet communication session entirely or just to leave the packet communication session such that this session resumable. The mobile sta- tion MS bases the decision on information comprised in the voice paging message URCA, wherein the information indicates either a voice call or a Short Message Service SMS message.

Referring now to fig. 3a, a table is shown that comprises the format of a voice paging message URCA according to the embodiment of the inventive method in figs. 1 and 2. The voice paging message URCA comprises a field called "Operator Specific Information". As shown in fig. 3b, this field comprises a first octet of bits for information to indicate the length of the operator specific information and a second octet of bits for the information indicative to the type of circuit call/communication service, i.e., voice call or Short Message Service (SMS) message. As shown in fig. 3c, in the example, in case the first bit of the second octet is high while bits 2 to 8 are low, a voice call is indicated; in case the second bit of the second octet is high while the first bit and bits 3 to 8 are low, a Short Message Service (SMS) message is indicated. Thus, reading the operator specific informa- tion in the voice paging message URCA, the mobile station MS obtains the information about the imminent Short Message Service (SMS) message and, in this case, immediately starts switching from the User Packet CHannel UPCH to the assigned traffic channel TCH. Any further indications of, for example, a short message services (SMS) message or a multimedia service (MMS) message, can be implemented by the use of the remaining bits of the operator specific field without any impact on the overall message structure. As shown in figs. 3a, 3b and 3c, the information on whether the incoming circuit call is a voice call or a Short Message Service (SMS) call, is comprised in the standard voice paging message URCA from the network NW to the mobile station MS and, more particularly, in the Operator Specific Information field of this standard message. Therefore, no upgrade is required on the standard, in order operate the network according to the inventive method. This is even better understood when referring to figs. 4, 5, figs. 6 and 7, and figs. 8 and 9 that show standard signaling sequences. As far as these standard signaling sequences and their explana- tion in the standard is concerned, the standard, RCR-STD 27, versions H and I, of the Association of Radio Industries and Businesses (ARIB), is herewith incorporated by reference.

Fig. 4 shows a first standard signaling sequence according to the embodiment in figs. 1 to 3, wherein the inventive paging signal is used. More particularly, fig. 4 shows a successful paging signaling sequence wherein the mobile station MS, denoted in fig. 4 as USER, is at first engaged in a packet data session with the network NW, the session being denoted in fig. 4 as "During packet communication (Active)", wherein the User Packet CHannel UPCH is used. The paging sig- naling sequence comprises the voice paging signal URCA, denoted in fig. 4 as "Ul (UPCH Radio Channel Assignment, -, -)", with the paging type indication as indicated in fig. 4. In particular, this voice paging signal URCA comprises the Operator Specific Information field (not shown in fig. 4). The Operator Specific Information field includes information on an imminent voice call. The mobile station MS determines to proceed with this voice call and entirely discards the packet data session such that, apart from signals related to the voice paging signal, no further communication takes place on the User Packet CHannel UPCH. Meanwhile, the voice call is set up and finally the voice call is in progress on the traffic channel TCH as indicated in fig. 4 by the bottom box "Call in progress". Fig. 5 shows a second standard signaling sequence according to the embodiment in figs. 1 to 3, wherein the inventive paging signal is used. More particularly, fig. 5 shows an unsuccessful paging signaling sequence wherein the mobile station MS, denoted in fig. 5 as USER, is at first engaged in a packet data session with the network NW, the session being denoted in fig. 4 as "During packet communication (Active)", wherein the User Packet CHannel UPCH is used. The paging signaling sequence comprises the voice paging signal URCA, denoted in fig. 5 as "Ul (UPCH Radio Channel Assignment, -, -)" with the paging type indication as indicated in fig. 5. In particular, this voice paging signal URCA comprises the Operator Specific Information field (not shown in fig. 5). The Operator Specific Information field includes information on an imminent voice call. The mobile station MS determines to proceed with the packet data session and, consequently, not to accept this voice call, effectively rejecting this voice call, indicated in fig. 5 by the arrow denoted "Ul (UPCH Voice Paging 2 Response, -, -)". Subsequently, the packet data session is continued as indicated in fig. 5 by the bottom box "Continue packet communication (Active)".

Figs. 6 and 7 show a third standard signaling sequence according to an alternative embodiment, wherein the inventive paging signal is used; the depiction of the se- quence starts in fig. 6 and is continued in fig. 7. Figs. 6 and 7 show the sequence for voice paging during packet communication (Active) (Voice Terminating Method 2; for the case when the UPCH Voice Paging 2 message is received), i.e. the sequences for the cases where the UPCH Voice Channel Request message is received directly during the packet communication (Active), which is accepted and not accepted. More particularly, figs. 6 and 7 show a successful paging signaling sequence wherein the mobile station MS, denoted in figs. 6 and 7 as USER, is at first engaged in an active packet data session with the network NW, wherein the User Packet CHannel UPCH is used. The paging signaling sequence comprises the voice paging signal URCA, denoted in fig. 7 as "Ul (UPCH Radio Channel Assignment, -, -)" with the paging type indication as indicated in fig. 7. In particular, this voice paging signal URCA comprises the Operator Specific In- formation field (not shown in figs. 6 and 7). The Operator Specific Information field includes information on an imminent voice call. The mobile station MS determines to proceed with this voice call and entirely discards the packet data session such that, apart from signals related to the voice paging signal, no further communication takes place on the User Packet CHannel UPCH. Meanwhile, the voice call is set up and finally the voice call is in progress on the traffic channel TCH as indicated in fig. 7 by the bottom box "Call in progress".

Figs. 8 and 9 show a fourth standard signaling sequence according to the alterna- tive embodiment, wherein the inventive paging signal is used; the depiction of the sequence starts in fig. 8 and is continued in fig. 9. Figs. 8 and 9 show the sequence for voice paging during packet communication (Packet standby) (Voice Paging Method 2), i.e. the sequences for the cases where the UPCH Voice Channel Request message is received during packet standby. More particularly, figs. 8 and 9 show a successful paging signaling sequence wherein the mobile station MS, denoted in figs. 8 and 9 as USER, is at first engaged in a packet data session with the network NW, wherein the User Packet CHannel UPCH is used. However, this packet data session is inactive, i.e., the packet data session is in packet standby mode. The paging signaling sequence comprises the voice paging signal URCA, denoted in fig. 9 as "Ul (UPCH Radio Channel Assignment, -, -)" with the paging type indication as indicated in fig. 9. In particular, this voice paging signal URCA comprises the Operator Specific Information field (not shown in figs. 8 and 9). The Operator Specific Information field includes information on an imminent voice call. The mobile station MS determines to proceed with this voice call and entirely discards the packet data session such that, apart from signals related to the voice paging signal, no further communication takes place on the User Packet CHannel UPCH. Meanwhile, the voice call is set up and finally the voice call is in progress on the traffic channel TCH as indicated in fig. 9 by the bottom box "Call in progress".

Claims

1. Communication service provisioning method for provision of communication service in a first mode to a mobile communication means engaged in a com- munication session in a second mode different from the first mode, comprising the steps: sending a paging message indicating an assignment of radio resources for a communication service in the first mode, keeping the second mode communication session, - sending a communication message comprising payload to the mobile communication means by way of the assigned radio resources while the second mode communication session is kept, and resuming the second mode communication session.

2. Communication service provisioning method according to the preceding claim, wherein the paging message comprises an indication of a type of communication service that radio resources are assigned for, wherein the type of the communication service can be one of at least voice call type and communication message type.

3. Communication service provisioning method according to claim 2, wherein the paging message is provided as a voice paging message indicating the assignment of radio resources for a communication service of the communication message type.

4. Communication service provisioning method according to any of the preceding claims, wherein said step of keeping the second mode communication session comprises repeatedly performing the steps of: - attempting retransmission of data of the second mode communication session, to the mobile communication means (MS), in the second mode, and waiting for a predetermined first interval of time, to receive a responsive transmission acknowledgement signal from the mobile communication means acknowledging reception of the retransmitted data of the second mode communication session, said steps being performed up to a predetermined number of retransmissions or until the transmission acknowledgment signal is received from the mobile communication means.

5. Communication service provisioning method according to any of the pre- ceding claims, wherein said step of keeping the second mode communication session comprises repeatedly performing the steps of: attempting transmission of a request for reestablishment of the second mode communication session, to the mobile communication means (MS), in the second mode, and waiting for a predetermined second interval of time, to receive a responsive reestablishment acknowledgement signal from the mobile communication means acknowledging reception of the request for reestablishment of the second mode communication session, said steps being performed up to a predetermined number of transmissions or until the reestablishment acknowledgment signal is received from the mobile communication means (MS).

6. Communication service acceptance method for acceptance, at a mobile communication means (MS), of a communication service in a first mode, particularly for interaction with a communication service provisioning method according to any of the preceding claims, said mobile communication means being engaged in a communication session in a second mode different from the first mode, comprising the steps: - receiving a paging message indicating an assignment of radio resources for communication service in the first mode, leaving said second mode communication session such that this session is resumable, receiving a communication message comprising payload information, and reactivating said second mode communication session such that this ses- sion is resumed.

7. Communication service acceptance method according to claim 6, wherein the paging message comprises an indication of a type of communication service that radio resources are assigned for, wherein the type of communication service can be one of at least voice call type and communication message type.

8. Communication service acceptance method according to claim 7, wherein the paging message is provided as a voice paging message indicating the assignment of radio resources for a communication service of the communication message type.

9. Communication service acceptance method according to any of claims 7 or 8, comprising the step: identifying the communication message by means of the communication service type indication comprised in the paging message, in order to perform, if the communication service type indication indicates a communication service of the communication message type, the steps of leaving the second mode communication session, receiving the communication message and reactivating the second mode communication session.

10. Communication service acceptance method according to any of claims 6 to

9, wherein the step of leaving the second mode communication session comprises switching of the mobile communication means into the first mode.

1 1. Communication service acceptance method according to any of claims 6 to

10, wherein the step of reactivating the second mode communication session comprises switching of the mobile communication means into the second mode.

12. Communication service acceptance method according to any of claims 6 to 1 1, wherein the step of reactivating the second mode communication session comprises receiving retransmitted data of the second mode communication session and, in response to the data reception, sending an acknowledgement signal.

13. Communication service acceptance method according to any of claims 6 to 12, wherein the step of reactivating the second mode communication session com- prises receiving a request for reestablishment of the second mode communication session, and, in response to the request reception, sending an acknowledgement signal.

14. Method according to any of the preceding claims, wherein said first mode is provided as a circuit switched mode, and wherein said second mode is provided as a packet switched mode and said second mode communication session is provided as a packet data communication session.

15. Method according to any of the preceding claims, wherein the paging message comprises a data field dedicated to operator specific information, wherein the operator specific information field comprises said communication service type indication.

16. Network node element, in particular a second type switching means (PMSC), of a cellular communication network, said network node element being adapted to perform a method according to any of the preceding communication service provisioning method claims.

17. Communication network comprising at least one network node element according to the preceding network node element claim.

18. Mobile communication means being adapted to perform a method according to any of the preceding communication service acceptance method claims.

19. Computer program, loadable into an internal memory of a digital processing unit, comprising software code portions adapted to control steps according to any of the preceding method claims, when the computer program is executed on the digital processing unit.

20. Computer program according to claim 19, wherein the computer program is stored on a machine-readable medium, in particular a computer-readable medium.