Methods and nodes for handling bearers

Abstract

The embodiments herein relate to a method performed by a gateway. The gateway detects that a procedure for activating or deactivating a bearer has been initiated. The gateway receives a first modify bearer or modify access bearers request message for the same PDN connection and UE as the bearer activation or deactivation procedure is intended for. The gateway detects a bearer mismatch between a first set of bearers and a second set of bearers known by the gateway and associated with said same PDN connection and UE. The gateway accepts, during a time interval, the received modify bearer or modify access bearers request message even though the bearer mismatch has been detected.

Claims

1. A method performed by a gateway for handling bearers in a communications system, the method comprising: detecting that a procedure for activating or deactivating a bearer has been initiated, wherein the bearer is associated with a network connection and a User Equipment (UE); receiving a first bearer modification request message, wherein the first bearer modification request message identifies a first set of one or more bearers associated with the network connection and the UE; detecting a first bearer mismatch between the first set of bearers and a second set of one or more bearers associated with the network connection and the UE; determining whether a condition is satisfied, wherein determining whether the condition is satisfied comprises determining whether the first bearer mismatch was detected during a particular time interval; and as a result of determining that the condition is satisfied, accepting the received bearer modification request message even though the first bearer mismatch has been detected.

2. The method of claim 1, further comprising starting a timer after detecting that the procedure has been initiated, wherein the particular time interval begins when the timer is started and ends when the timer expires.

3. The method of claim 2, further comprising: detecting that the timer has expired; after the timer has expired, receiving a second bearer modification request message after the timer has expired, wherein the second bearer modification request message identifies a third set of bearers associated with the network connection and the UE; after receiving the second bearer modification message, detecting a second bearer mismatch between the third set of bearers and the second set of bearers associated with the network connection and the UE; and applying error handling of the detected bearer mismatch as a result of detecting the second bearer mismatch and detecting that the timer had expired before the bearer mismatch was detected.

4. The method of claim 2, wherein the time interval is a period of time during which a risk of a racing condition in the communication system has increased since the bearer activation or deactivation procedure has been initiated.

5. The method of claim 2, wherein the timer expires after a predetermined amount of time.

6. The method of claim 1, wherein the time interval lasts until the first request message is received without any bearer mismatch.

7. The method of claim 1, wherein a mobility node transmitted the first bearer modification request message, and the method further comprises transmitting information associated with the first bearer mismatch to the mobility node.

8. The method of claim 7, wherein the information associated with the first bearer mismatch indicates at least one bearer which is missing or unknown in the first bearer modification request message.

9. The method of claim 1, further comprising: setting a flag after detecting that the procedure has been initiated, wherein the flag indicates that the bearer activation or deactivation procedure is pending; and where the time interval lasts while the flag is set.

10. The method of claim 9, wherein the flag is a dedicated bearer activation flag or a dedicated bearer deactivation flag.

11. The method of claim 1, further comprising: informing at least one of another gateway or a mobility node that the gateway supports handling of bearer mismatch; and receiving from at least one of the other gateway or the mobility node, support information indicating that they support the handling of bearer mismatch.

12. The method of claim 1, wherein the network connection is a Packet Data Network (PDN) connection, and the bearer is an Evolved Packet System (EPS) bearer and/or a dedicated bearer.

13. A gateway for handling bearers in a communications system, the gateway comprising: a memory; and processing circuitry coupled to the memory, wherein the gateway is adapted to: detect that a procedure for activating or deactivating a bearer has been initiated, wherein the bearer is associated with a network connection and a User Equipment (UE); receive a first bearer modification request message, wherein the first bearer modification request message identifies a first set of bearers associated with the network connection and the UE; detect a first bearer mismatch between the first set of bearers and a second set of bearers associated with the network connection and the UE; determine whether a condition is satisfied, wherein the gateway is configured to determine whether the condition is satisfied by performing a process that comprises determining whether the first bearer mismatch was detected during a particular time interval; and as a result of determining that the condition is satisfied, accept the received bearer modification request message even though the first bearer mismatch has been detected.

14. The gateway of claim 13, wherein the gateway is further adapted to start a timer after detecting that the procedure has been initiated, wherein the particular time interval begins when the timer is started and ends when the timer expires.

15. The gateway of claim 14, being further adapted to: detect that the timer has expired; after the timer has expired, receive a second bearer modification request message after the timer has expired, wherein the second bearer modification request message identifies a third set of bearers associated with the network connection and the UE; after receiving the second bearer modification message, detect a second bearer mismatch between the third set of bearers and the second set of bearers associated with the network connection and the UE; and apply error handling of the detected bearer mismatch as a result of detecting the second bearer mismatch and detecting that the timer had expired before the bearer mismatch was detected.

16. The gateway of claim 14, wherein the timer is a period that the risk of a racing condition in the communication system has increased since the bearer activation or deactivation procedure has been initiated.

17. The gateway of claim 14, wherein the timer expires after a predetermined amount of time.

18. The gateway of claim 13, wherein the time interval lasts until the first bearer modification request message is received without any bearer mismatch.

19. The gateway of claim 13, wherein a mobility node transmitted the first bearer modification request message, and the method and the gateway being further adapted to transmit information associated with the bearer mismatch to the mobility node.

20. The gateway of claim 19, wherein the information associated with the bearer mismatch indicates at least one bearer which is missing or unknown in the first received modify bearer or modify access bearers request message.

21. The gateway of claim 13, being further adapted to set a flag after detecting that the procedure has been initiated, wherein the flag indicates that the bearer activation or deactivation procedure is pending, wherein the time interval lasts while the flag is set.

22. The gateway of claim 21, wherein the flag is a dedicated bearer activation flag or a dedicated bearer deactivation flag.

23. The gateway of claim 13, being further adapted to: inform at least one of another gateway or a mobility node that the gateway supports handling of bearer mismatch; and receive from at least one of the other gateway or the mobility node that they support the handling of bearer mismatch.

24. The gateway of claim 13, wherein the bearer is an Evolved Packet System (EPS) bearer, and/or the bearer is a dedicated bearer.

25. The gateway of claim 13, wherein the network connection is a Packet Data Network (PDN) connection, and the gateway is a Serving Gateway or a PDN Gateway.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The embodiments herein will now be further described in more detail in the following detailed description by reference to the appended drawings illustrating the embodiments and in which:

(2) FIG. 1 is a schematic block diagram illustrating a known communications system wherein embodiments of the present solution can be implemented.

(3) FIG. 2 is a signaling diagram illustrating an example of Bearer Mismatch as a Result of a Connectivity Problem or a Temporary Overload.

(4) FIG. 3 is a signaling diagram illustrating a Procedure Using Modify Bearer Request.

(5) FIG. 4 is a signaling diagram illustrating a procedure Using Modify Access Bearers Request.

(6) FIG. 5 is a signaling diagram illustrating a Default Bearer Activation procedure.

(7) FIG. 6 is a signaling diagram illustrating a Dedicated Bearer Activation procedure.

(8) FIG. 7 is a signaling diagram illustrating a Bearer Activation Procedure.

(9) FIG. 8 is a signaling diagram illustrating a procedure for Racing Condition: Create Bearer Response and Modify Bearer Request, case 1.

(10) FIG. 9 is a signaling diagram illustrating a procedure for Racing Condition: Create Bearer Response and Modify Bearer Request, case 2.

(11) FIG. 10 is a signaling diagram illustrating a procedure for Racing Condition: Create Bearer Response and Modify Bearer Request, case 3.

(12) FIG. 11 is a signaling diagram illustrating a procedure for Racing Condition: Create Bearer Response and Modify Bearer Request, case 4.

(13) FIG. 12 is a signaling diagram illustrating a procedure for Racing Condition: Create Bearer Response and Modify Bearer Request.

(14) FIG. 13 is a table showing an overview of a create scenario for case 1-4 in the SGW.

(15) FIG. 14 is a table showing an overview of a delete scenario for case 5-8 in the SGW.

(16) FIG. 15 is a schematic block diagram illustrating embodiments of a communications system.

(17) FIG. 16 is a signaling diagram illustrating embodiments of a method.

(18) FIG. 17 is a signaling diagram illustrating embodiments of a method.

(19) FIG. 18 is a flow chart illustrating embodiments of a method performed by a gateway.

(20) FIG. 19 is a schematic block diagram illustrating embodiments of a gateway.

(21) FIG. 20 is a flow chart illustrating embodiments of a method performed by a mobility node.

(22) FIG. 21 is a schematic block diagram illustrating embodiments of a mobility node.

(23) The drawings are not necessarily to scale and the dimensions of certain features may have been exaggerated for the sake of clarity. Emphasis is instead placed upon illustrating the principle of the embodiments herein.

DETAILED DESCRIPTION

(24) FIG. 15 depicts a communications system 100 in which embodiments discussed herein may be implemented. The communications network 100 may in some embodiments apply to one or more radio access technologies such as for example Long Term Evolution (LTE), LTE Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile Communications (GSM), or any other Third Generation Partnership Project (3GPP) radio access technology, or other radio access technologies (both 3GPP and non-3GPP technologies) such as e.g. WLAN. The communications network 100 may be referred to as a wireless communications network, a wireless network, a wireless communications system, a system or a network.

(25) The communications system 100 comprises a mobility node 1305, a first gateway 1308, a second gateway 1310 and a policy node 1330.

(26) The mobility node is a node which is responsible for handling mobility procedures in the communications system 100, it is involved in the bearer activation/deactivation process etc. The mobility node 1305 may correspond to the MME 105 in FIG. 1, an S4-SGSN, a combined MME/S4-SGSN, an ePDG, a TWAN, a vMME, a vSGSN etc. The mobility node 1305 may be an actual node or it may be a function implemented in a node.

(27) The first gateway 1308 may for example correspond to a SGW as in FIG. 1 and the second gateway 1310 may for example correspond to a PGW 110 as in FIG. 1. Each of the gateways may be actual gateway nodes or they may be functions implemented in a node. The term gateway may be used when referring to any of the first and second gateways. Both the reference numbers 1308, 1310 will be used when referring to any of the first and second gateways.

(28) The policy node 1330 is a node which is responsible for handling policies in the communications system 100. The policy node 1330 may correspond to a PCRF 130 as in FIG. 1. The policy node 1330 may be an actual policy node or it may be a function implemented in a node.

(29) The mobility node 1305 may be connected to the first gateway 1308, the first gateway 1308 may be connected to the second gateway 1310 and the second gateway 1310 may be connected to the policy node 1330.

(30) An overview of the nodes in the communications system 100 is seen in

(31) Table below:

(32) TABLE-US-00002 TABLE 2 Gateway 1301. Mobility 1308. First 1310. Second 1330. Policy node gateway gateway node MME SGW PGW PCRF S4-SGSN SGW PGW PCRF MME/S4- PCRF SGSN ePDG SGW PGW PCRF TWAN SGW PGW PCRF

(33) It should be noted that the communication links in the communications system 100 may be of any suitable kind including either a wired or wireless link. The link may use any suitable protocol depending on type and level of layer (e.g. as indicated by the OSI model) as understood by the person skilled in the art. Further note that the communications system 100 exemplified in FIG. 15 may comprise additional nodes and entities, such as e.g. the nodes illustrated in FIG. 1. However, only the mobility node 1305, the first gateway 1308, the second gateway 1310 and the policy node 1330 are illustrated in FIG. 15 for the sake of simplicity.

(34) The method for handling bearers in a communications system, according to some embodiments will now be described with reference to the signaling diagram in FIG. 16. The method comprises the following steps, which steps may as well be carried out in another suitable order than described below:

(35) Step 1401

(36) At least one of the mobility node 1301, the gateway 1308, 1310 and the policy node 1310 may inform each other that they support handling of bearer mismatch. The bearer may be an EPS bearer. The bearer may be a dedicated bearer. This may be done by transmission of support information.

(37) It is not necessary that all of the mobility node 1301, the gateway 1308, 1310 and the policy node 1310 support the handling of bearer mismatch. For example, it may be only the first gateway 1308 corresponding to the SGW 108 which support the handling of bearer mismatch (in procedures with only S11/4 signaling and no S5/S8 signaling), i.e. the mobility node 1301 corresponding to the MME 105 and the second gateway 1310 corresponding to the PGW 110 does not have to support it.

(38) For procedures in which the Modify Bearer Request/Modify Access Bearers Request messages are sent only over the S11/S4 interval (i.e. when there is no S5/S8 signaling), the PGW 110 (in an example where the second gateway 1310 corresponds to the PGW 110) does not necessarily need to support the handling of bearer mismatch.

(39) The embodiments described herein works even if the MME/S4-SGSN 105 (in an example where the mobility node 1301 corresponds to the MME/S4-SGSN 105) does not support the handling of the bearer mismatch. The reason it works even in these cases is that SGW 108 (in an example where the first gateway 1308 corresponds to the SGW 108) actually accepts the Modify Bearer Request/Modify Access Bearers Request message even if there is a (temporary) bearer mismatch between the message and the information stored in the SGW 108. The MME 105 does not need to do anything.

(40) In an alternative embodiment, the SGW 108 may reject the “failing” bearers but keep them, and let the MME 105 decide whether to keep or delete the “failing” bearers. In such embodiment, the MME/S4-SGSN 105 needs to support the handling of bearer mismatch.

(41) The step of informing of the support for handling bearer mismatch may also be referred to as a capability exchange between at least some of the mobility node 1301, the gateway 1308, 1310 and the policy node 1310. The following list presents two examples of how the capability exchange may be performed: i. Using a Supported feature announcement with Echo request/response messages. ii. Using PDN connection signaling, i.e. to include a support indication in Create Session Request/Response messages (for PDN connection creation procedure) and Modify Bearer Request/Response messages for a SGW relocation procedure.

(42) Step 1402

(43) The gateway 1308, 1310 detects that a procedure for activating or deactivating a bearer has been initiated. The bearer is associated with a PDN connection and a UE 101. The procedure for activating a bearer may correspond to a Create Bearer Request procedure (e.g. step 1504 in FIG. 15) and the procedure for deactivating a bearer may correspond to a Delete Bearer Request procedure.

(44) Step 1403

(45) The gateway 1308, 1310 may start a timer when the procedure has been detected. A time interval lasts while the timer is running. The timer may a period that the risk of a racing condition in the communication system 100 has increased since the bearer activation or deactivation procedure has been initiated. The timer may expire after a predetermined amount of time. The timer may correspond to a certain period after the procedure has been detected.

(46) This period may be achieved in some alternative ways in addition to the use of a timer, which will be described in detail with reference to step 1406 below.

(47) In step 1403, the gateway 1308, 1310 may also set a flag when the procedure has been detected. The flag may indicate that the bearer activation or deactivation procedure is pending. The flag may be a dedicated bearer activation flag or a dedicated bearer deactivation flag.

(48) In some embodiments, the timer may be started. In other embodiments, the flag may be set. In yet further embodiments, both the timer and the flag may be started and set.

(49) Step 1404

(50) The mobility node 1301 sends a first modify bearer or modify access bearers request message to the gateway 1308, 1310 for the same PDN connection and UE 101 as the bearer activation or deactivation procedure is intended for. The gateway 1308, 1310 receives the first modify bearer or modify access bearers request message from the mobility node 130. The message identifies a first set of bearers associated with said same PDN connection and UE 101. The first set may be e.g. EBI={5,6}.

(51) Step 1405

(52) The gateway 1308, 1310 detects at least one bearer mismatch between the first set of bearers and a second set of bearers known by the gateway 1308, 1310 and associated with said same PDN connection and UE 101. The first set of bearers may also be referred to as a first set of bearer contexts, and the second set of bearers may also be referred dot as a second set of bearer contexts.

(53) The first set may be e.g. EBI={5,6} and the second set may be EBI={5}.

(54) In an example of a Modify (access) Bearer Request message, the message shall contain a complete set of bearer context for the given (UE 101) [for the modify access bearer request case]) PDN connection. Thus, the MME/SGW/PGW 105, 108, 110 is able to detect any possible mismatch.

(55) The first set of bearers is included in the messages (Modify Bearer Request or Modify Access Bearers Request) from the mobility node 1301, and the second set of bearers is a list stored in the receiving node, i.e. the gateway 1308, 1310 (for example the SGW 108 and/or the PGW 108).

(56) Step 1406

(57) The gateway 1308, 1310 accepts, during a time interval from the procedure has been detected, the received modify bearer or modify access bearers request message even though the bearer mismatch has been detected.

(58) The time interval may last while the timer in step 1403 is running. The time interval may last while the flag in step 1403 is set.

(59) For example, the time interval may last until some kind of acknowledge message or similar is received. The time interval may last until the first modify bearer or the modify access bearers request message is received without any bearer mismatch. It may e.g. be that the MME 105 determines to send some kind of message to the gateway 1308, 1310, where the message is associated with the mismatch detected in step 1405 and reported to the MME 101 in step 1407. In such cases there is not necessarily any timer in use in the gateway 1308, 1310 (possibly in the MME 105). Also, it may be that the time interval may last until the next modify bearer request or modify access bearer request is received by the gateway 1308, 1310. The gateway 1308, 1310 may receive two consecutive Modify Bearer Request messages within the time interval, and then both Modify Bearer Request messages should be accepted.

(60) The time interval may be a predetermined time interval. The time interval may be predetermined in that the timer is set to a certain predetermined value in seconds or similar.

(61) The gateway 1308, 1310 does not have to use a timer, but only a flag.

(62) An advantage with the timer is that it covers the case where no Modify Bearer Request is received (and hence no racing).

(63) By only using a flag and no timer, a faulty Modify Bearer Request message that arrives “much later” may be erroneously accepted. However, the possible mistake will be corrected at the next Modify Bearer Request message.

(64) When the gateway 1308, 1310 receives a Create/Delete Bearer Request message, the gateway 1308, 1310 sets the flag and (optionally) sets the timer. The gateway 1308, 1310 may clears the flag when the gateway 1308, 1310 has replied to the first Modify Bearer Request after the Create/Delete Bearer Request message, or when the timer (if set) elapses, whichever occurs first.

(65) Below is a list of some examples of the flag and timer: A) Timer (the timer can serve as a flag); B) Timer and flag; C) Flag only.

(66) Step 1407

(67) The gateway 1308, 1310 may transmit information associated with the bearer mismatch to the mobility node 1305. The mobility node 1305 may receive the information associated with the bearer mismatch from the gateway 1308, 1310.

(68) The information associated with the bearer mismatch may indicates at least one bearer which is missing or unknown in the first received modify bearer or modify access bearers request message.

(69) Step 1408

(70) Based on the information received in step 1407, the mobility node 1305 may determine if there is a need for a further action associated with the bearer mismatch.

(71) Step 1409

(72) The gateway 1308, 1310 may detect that the timer has expired, i.e. the timer which may have been started in step 1403.

(73) The timer may expire or end, either detecting the mismatch, or detecting a match, or when the timer is a predefined timer (e.g. N3×T3, taking into account of GTP re-transmission).

(74) Step 1410

(75) The mobility node 1301 may send a subsequent modify bearer or modify access bearers request message to the gateway 1308, 1310 after the timer has expired. The gateway 1308, 1310 may receive the subsequent modify bearer or modify access bearers request message from the mobility node 1301 after the timer has expired. The message identifies a third set of bearers associated with said same PDN connection and UE 101. The message is subsequent to the first modify bearer or modify access bearers request message in step 1404.

(76) Step 1411

(77) When the timer has expired, the gateway 1308, 1310 may detect at least one bearer mismatch between the third set of bearers and the second set of bearers known by the gateway 1308, 1310 and associated with said same PDN connection and UE 101.

(78) Step 1412

(79) The gateway 1308, 1310 may apply error handling of the bearer mismatch when the timer has expired. The error handling may be for example rejection, partial accept, local deletion of bearers etc.

(80) An example of the method above will now be described with reference to FIG. 17. In FIG. 17, the mobility node 1305 is exemplified with an MME 105, the first gateway 1308 is exemplified with a SGW 108, the second gateway 1310 is exemplified with a PGW 110 and the policy node 1330 is exemplified with a PCRF 130. The method illustrated in FIG. 17 comprises at least some of the following steps, which steps may be performed in any suitable order than described below:

(81) Step 1501-1503

(82) The MME 105, the SGW 108 and the PGW 110 indicate their support for the proposed solution/feature for handling of bearer mismatch, either by using Echo Request/Response (as described in the GTP standard) or by using a dedicated indication or flag in the Create Session Request/Response message. So, using the Echo Request/Response is an alternative to using a flag in the Create Session Request/Response message.

(83) In detail, the PGW 110 may send an Echo Request message to the SGW 108. The Echo request may comprise an indication of that the PGW 110 supports the handling of bearer mismatch according to the embodiments herein. The SGW 108 may receive the Echo Request message from the PGW 110, and the SGW 110 may sends an Echo Reply message to the PGW 110 also indicating that the SGW 110 supports the handling of bearer mismatch. Similarly, the SGW 108 may send an Echo Request message to the MME 105 with an indication of that the SGW 108 supports the handling of bearer mismatch. The MME 105 receives the Echo Request, and the MME 105 sends an Echo Reply to the SGW 110 with an indication of that the MME 105 supports the handling of bearer mismatch. Thus, all nodes in the communications system 100 may have information indicating that the other nodes also support the handling of bearer mismatch.

(84) As an alternative to the Echo Request/Response, as mentioned above, the MME 105 may send a Create Session Request message to the SGW 108 comprising an indication of the support of handling of bearer mismatch. The SGW 108 may forward the message to the PGW 110, and the PGW 110 may forward the message to the PCRF 130. The PCRF 130 may send a Create Session Response message to the PGW 110 comprising an indication of the support of handling of bearer mismatch. The PGW 110 may forward the Create Session Response message to the SGW 108, and the SGW 108 may forward the Create Session Response message to the MME 105. The Create Session Request and Response messages may comprise the indication in the form of a flag.

(85) The support for the embodiments described herein for handling for bearer mismatching during the possible race condition needs a handshake between the SGW 108 and the PGW 110, and between the SGW 108 and the MME 105. The purpose of the handshake is that the nodes in the communications system 100 inform each other about their support for handling of bearer mismatch. The handshake refers to either the Echo Request/Response or the Create Session Request message comprising the indication of the support of handling of bearer mismatch described above. The handshake may be provided by using Supported feature advertisement as specified in TS 29.274, version 13.4.0, sub clause 11. In general, a node supporting at least one feature defined in the Node Features IE shall support dynamic discovery of supported features. The Supported feature advertisement involves that a node shall signal to a direct peer node the list of features it supports by sending the Sending Node Features IE in the Echo Request and Echo Response messages. The peer receiving the Sending Node Features IE shall store the list of features supported by the sending node per IP address and only update this list based on the Sending Node Features IE in the Echo Request and Echo Response messages, and it shall only use common supported features to initiate subsequent GTPv2 messages towards this IP address.

(86) The Supported feature advertisement is useful since, e.g. for the case when Create Bearer Response is received first (the new bearer has been created); while the Modify Bearer Request contains no newly created bearer, if only SGW 108 support the embodiments described herein, while PGW 110 does not support, there may be a risk, that PGW 110 considering that the new dedicated bearer is not created, and initiated a new creation procedure.

(87) As an alternative, such exchange of the support for such handling for bearer mismatching during the possible race condition may be done during PDN connection establishment and updated during a SGW 108 relocation procedure.

(88) Step 1504

(89) The PGW 110 sends a Create Bearer Request message to the SGW 108. The SGW 108 receives the Create Bearer Request message. The SGW 108 forwards the Create Bearer Request message to the MME 105.

(90) Step 1505

(91) When the SGW 108 and the PGW 110 receives Create Bearer Request, each of them set a (configurable) timer. While the timer is running, the SGW/PGW should treat the first received Modify Bearer Request “with forgiveness”. When the Modify Bearer Request has been answered, the timer may be stopped. “With forgiveness” refers to that while the timer is running, the PGW/SGW 110, 108 should ignore any bearer mismatch in the first received Modify Bearer Request/Modify Access Bearers Request for the same PDN Connection/UE 101, as described in step 1508 below.

(92) When PGW/SGW 110, 108 has started to handle a Create Bearer Request message, or a Delete Bearer Request message, each of the PGW/SGW 110, 108 should set start a locally configurable time, and set a flag.

(93) After the timer has been stopped SGW/PGW should treat Modify Bearer Request normally.

(94) Step 1506

(95) The MME 105 sends a Create Bearer Response message to the SGW 108, for further transmission to the PGW 110. The Create Bearer Response message may comprise an indication of the bearer with the EBI={6} which is the bearer which should be created.

(96) Step 1507

(97) The MME 105 sends a Modify Bearer Request message to the SGW 108, for further transmission to the PGW 110. The Modify Bearer Request message may comprise an indication of the bearer with the EBI={5} or EBI={5,6} which is the bearer(s) which should be modified. The Modify Bearer Request message is the first Modify Bearer Request message after the Create Session Request message in step 1502. This step is equally applicable to a Modify Access Bearers Request message.

(98) The Create Bearer Response message and the Modify Bearer Request message may not be received by the SGW 108 or the PGW 110 in the same order as they were sent from the MME 105, as indicated with the clouds and the dotted crossed lines in FIG. 15.

(99) Step 1508

(100) While the timer is running the PGW/SGW 110, 108 should ignore any bearer mismatch in the first received Modify Bearer Request message for the same PDN Connection/UE 101. If the PGW/SGW 110, 108 detects a bearer mismatch in the message, the PGW/SGW 110, 108 should accept the request to the message as if there were no bearer mismatch, and in the corresponding Modify Bearer Response message, the S(P)GW 110, 108 may add a new information element with information about the unknown/missing bearers. The information may be in the form of a list of the unknown/missing bearers in the mismatch. Based on the received information, the MME/SGSN 105 can determine if there is a need for the further action, e.g. the S(P)GW has wrongly accepted the unknown bearer(s).

(101) The Modify Bearer Response message is transmitted from the PGW 110 to the SGW 108. The Modify Bearer Response is then received by the SGW 108 from the PGW 110. The Modify Bearer Response message is transmitted from the SGW 108 to the MME 105.

(102) The information element with the information about the unknown/Missing bearers may be of the IE Type “Private Extension”, or a regular information element, such as for example of the IE Type “Bearer Context”.

(103) This step is equally applicable to a Modify Access Bearers Request message.

(104) Step 1509

(105) After the timer has expired, or after the first Modify Bearer Request for the same PDN Connection/UE has been handled—whichever comes first—the PGW/SGW 110, 108 may resume regular handling of subsequent Modify Bearer Request message. This step is equally applicable to a Modify Access Bearers Request message.

(106) In the scenarios described in FIGS. 10 and 11 above, the gateway 1308, 1310 (which may correspond to a PGW 110 and SGW 108) should be aware that a dedicated bearer is being created, and neither reject the Modify Bearer Request nor delete the newly created dedicated bearer with the embodiments herein as described in relation to FIGS. 16 and 17.

(107) With the embodiments described herein, the risk in the “Create scenario” that either the newly created bearer(s), or the entire PDN connection, is torn down in case of a bearer mismatch is at least reduced or removed. Furthermore, the risk in the “Delete scenario” that the entire PDN connection is torn down in case of a bearer mismatch is also at least reduced or removed with the embodiments herein.

(108) The method described above will now be described seen from the perspective of the gateway. FIG. 18 is a flowchart describing the present method performed by the gateway 108, 110, 1308, 1310 for handling bearers in the communications system 100. The gateway 108, 110, 1308, 1310 may be a first gateway 1308, and the first gateway 1308 may be a SGW 108. The gateway 108, 110, 1308, 1310 may be a second gateway 1310, and the second gateway 1310 is a PGW 110.

(109) The method comprises at least some of the following steps to be performed by the gateway 108, 110, 1308, 1310, which steps may be performed in any suitable order than described below:

(110) Step 1801

(111) This step corresponds to step 1401 in FIG. 16 and step 1501 in FIG. 17. The gateway 108, 110, 1308, 1310 may inform at least one of another gateway 108, 110, 1308, 1310 and a mobility node 105, 1301 that the gateway 108, 110, 1308, 1310 supports handling of bearer mismatch. The bearer may be an EPS bearer. The bearer may be a dedicated bearer.

(112) Step 1802

(113) This step corresponds to step 1401 in FIG. 16 and step 1501 in FIG. 17. The gateway 108, 110, 1308, 1310 may receive support information from at least one of the other gateway 108, 110, 1308, 1310 and the mobility node 105, 1301 that they support the handling of bearer mismatch.

(114) Step 1803

(115) This step corresponds to step 1402 in FIG. 16 and step 1504 in FIG. 17. The gateway 108, 110, 1308, 1310 detects that a procedure for activating or deactivating a bearer has been initiated. The bearer is associated with a PDN connection and a UE 101.

(116) Step 1804

(117) This step corresponds to step 1403 in FIG. 16 and step 1505 in FIG. 17. The gateway 108, 110, 1308, 1310 may start a timer when the procedure has been detected. The time interval may last while the timer is running.

(118) The timer may be a period that the risk of a racing condition in the communication system 100 has increased since the bearer activation or deactivation procedure has been initiated.

(119) Step 1805

(120) This step corresponds to step 1403 in FIG. 16. The gateway 108, 110, 1308, 1310 may set a flag when the procedure has been detected. The flag may indicate that the bearer activation or deactivation procedure is pending. The time interval may last while the flag is set. The flag may be a dedicated bearer activation flag or a dedicated bearer deactivation flag.

(121) Step 1806

(122) This step corresponds to step 1404 in FIG. 16 and step 1507 in FIG. 17. The gateway 108, 110, 1308, 1310 receives a first modify bearer or modify access bearers request message from a mobility node 105, 1305 for the same PDN connection and UE 101 as the bearer activation or deactivation procedure is intended for. The message identifies a first set of bearers associated with said same PDN connection and UE 101.

(123) Step 1807

(124) This step corresponds to step 1405 in FIG. 16. The gateway 108, 110, 1308, 1310 detects at least one bearer mismatch between the first set of bearers and a second set of bearers known by the gateway 108, 110, 1308, 1310 and associated with said same PDN connection and UE 101.

(125) Step 1808

(126) This step corresponds to step 1406 in FIG. 16. The gateway 108, 110, 1308, 1310 accepts, during a time interval from the procedure has been detected, the received modify bearer or modify access bearers request message even though the bearer mismatch has been detected.

(127) The time interval may last until the first modify bearer or the modify access bearers request message is received without any bearer mismatch.

(128) Step 1809

(129) This step corresponds to step 1407 in FIG. 16 and step 1508 in FIG. 17. The gateway 108, 110, 1308, 1310 may transmit information associated with the bearer mismatch to the mobility node 105, 1305.

(130) The information associated with the bearer mismatch may indicate at least one bearer which is missing or unknown in the first received modify bearer or modify access bearers request message.

(131) Step 1810

(132) This step corresponds to step 1409 in FIG. 16. The gateway 108, 110, 1308, 1310 may detect that the timer has expired.

(133) The timer may expire after a predetermined amount of time.

(134) Step 1811

(135) This step corresponds to step 1410 in FIG. 16 and step 1509 in FIG. 17. The gateway 108, 110, 1308, 1310 may receive subsequent modify bearer or modify access bearers request message after the timer has expired. The message identifies a third set of bearers associated with said same PDN connection and UE 101.

(136) Step 1812

(137) This step corresponds to step 1411 in FIG. 16. When the timer has expired, the gateway 108, 110, 1308, 1310 may detect at least one bearer mismatch between the third set of bearers and the second set of bearers known by the gateway 108, 110, 1308, 1310 and associated with said same PDN connection and UE 101.

(138) Step 1813

(139) This step corresponds to step 1412 in FIG. 16. The gateway 108, 110, 1308, 1310 may apply error handling of the bearer mismatch when the timer has expired.

(140) To perform the method steps shown in FIG. 18 for handling bearers in the communications system 100, the gateway 108, 110, 1308, 1310 may comprise an arrangement as shown in FIG. 19. The gateway 108, 110, 1308, 1310 may be a first gateway 1308, and the first gateway 1308 may be a SGW 108. The gateway 108, 110, 1308, 1310 may be a second gateway 1310, and the second gateway 1310 may be a PGW 110. To perform the method steps shown in FIG. 18 for handling bearers in the communications system 100, the gateway 108, 110, 1308, 1310 is adapted to, e.g. by means of a detecting module 1901, detect that a procedure for activating or deactivating a bearer has been initiated. The bearer is associated with a PDN connection and a UE 101. The bearer may be an EPS bearer. The bearer may be a dedicated bearer. The detecting module 1901 may also be referred to as a detecting unit, a detecting means, a detecting circuit, means for detecting etc. The detecting module 1901 may be a processor 1903 of the gateway 108, 110, 1308, 1310.

(141) The gateway 108, 110, 1308, 1310 is adapted to, e.g. by means of a receiving module 1905, to receive a first modify bearer or modify access bearers request message from a mobility node 105, 1305 for the same PDN connection and UE 101 as the bearer activation or deactivation procedure is intended for. The message identifies a first set of bearers associated with said same PDN connection and UE 101. The receiving module 1905 may also be referred to as a receiving unit, a receiving means, a receiving circuit, means for receiving, input unit etc. The receiving module 1905 may be a receiver, a transceiver etc. The receiving module 1905 may be a wireless receiver of the gateway 108, 110, 1308, 1310 of a wireless or fixed communications system.

(142) The gateway 108, 110, 1308, 1310 is adapted to, e.g. by means of the detecting module 1901, detect at least one bearer mismatch between the first set of bearers and a second set of bearers known by the gateway 108, 110, 1308, 1310 and associated with said same PDN connection and UE 101.

(143) The gateway 108, 110, 1308, 1310 is adapted to, e.g. by means of an accepting module 1910, accept, during a time interval from the procedure has been detected, the received modify bearer or modify access bearers request message even though the bearer mismatch has been detected. The time interval may last until the first modify bearer or the modify access bearers request message is received without any bearer mismatch. The accepting module 1910 may also be referred to as an accepting unit, an accepting means, an accepting circuit, means for accepting etc. The accepting module 1910 may be the processor 1903 of the gateway 108, 110, 1308, 1310.

(144) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of a starting module 1913, start a timer when the procedure has been detected. The time interval lasts while the timer is running. The time interval corresponds to that the gateway 108, 110, 1308, 1310 is adapted to start the timer. The timer may be a period that the risk of a racing condition in the communication system 100 has increased since the bearer activation or deactivation procedure has been initiated. The timer may expire after a predetermined amount of time. The starting module 1913 may also be referred to as a starting unit, a starting means, a starting circuit, means for starting etc. The starting module 1901 may be the processor 1903 of the gateway 108, 110, 1308, 1310.

(145) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of the detecting module 1901, detect that the timer has expired.

(146) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of the receiving module 1905, receive subsequent modify bearer or modify access bearers request message after the timer has expired. The message identifies a third set of bearers associated with said same PDN connection and UE 101.

(147) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of the detecting module 1901, when the timer has expired, detect at least one bearer mismatch between the third set of bearers and the second set of bearers known by the gateway 108, 110, 1308, 1310 and associated with said same PDN connection and UE 101.

(148) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of an applying module 1915, apply error handling of the bearer mismatch when the timer has expired. The applying module 1915 may also be referred to as an applying unit, an applying means, an applying circuit, means for applying etc. The applying module 1915 may be the processor 1903 of the gateway 108, 110, 1308, 1310.

(149) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of a transmitting module 1919, transmit information associated with the bearer mismatch to the mobility node 105, 1305. The information associated with the bearer mismatch may indicate at least one bearer which is missing or unknown in the first received modify bearer or modify access bearers request message. The transmitting module 1919 may also be referred to as a transmitting unit, a transmitting means, a transmitting circuit, means for transmitting, output unit etc. The transmitting module 1919 may be a transmitter, a transceiver etc. The transmitting module 1919 may be a wireless transmitter of the gateway 108, 110, 1308, 1310 of a wireless or fixed communications system.

(150) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of a setting module 1922, set a flag when the procedure has been detected. The flag indicates that the bearer activation or deactivation procedure is pending. The time interval may last while the flag is set. The flag may be a dedicated bearer activation flag or a dedicated bearer deactivation flag. The setting module 1922 may also be referred to as a setting unit, a setting means, a setting circuit, means for setting etc. The setting module 1922 may be the processor 1903 of the gateway 108, 110, 1308, 1310.

(151) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of the transmitting module 1919, inform at least one of another gateway 108, 110, 1308, 1310 and a mobility node 105, 1301 that the gateway 108, 110, 1308, 1310 supports handling of bearer mismatch.

(152) The gateway 108, 110, 1308, 1310 may be adapted to, e.g. by means of the receiving module 1905, receive from at least one of the other gateway 108, 110, 1308, 1310 and the mobility node 105, 1301 that they support the handling of bearer mismatch.

(153) In some embodiments, the gateway 108, 110, 1308, 1310 comprises the processor 1903 and a memory 1925. The memory 1925 comprises instructions executable by the processor 1925. The memory 1925 may comprise one or more memory units. The memory 1925 is arranged to be used to store data, received data streams, timer, flag, information about procedures, mismatch information, time intervals, request and response messages, set of bearers, information indicating PDN connections and UE, information associated with bearer mismatch, support information, information indicating a race condition, power level measurements, threshold values, time periods, configurations, schedulings, and applications to perform the methods herein when being executed in the gateway 108, 110, 1308, 1310.

(154) Those skilled in the art will also appreciate that the detecting module 1901, the receiving module 1905, the accepting module 1910, the starting module 1913, the applying module 1915, the transmitting module 1919 and the setting module 1922 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processor 1903 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

(155) In some embodiments, a first computer program may comprise instructions which, when executed on at least one processor, cause the at least one processor to carry out the relevant method steps in FIGS. 16, 17 and 18. A first carrier may comprise the first computer program, and the first carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

(156) The method described above will now be described seen from the perspective of the mobility node 105, 1305. FIG. 20 is a flowchart describing the present method performed by the mobility node 105, 1305 for handling bearers in the communications system 100. The bearer may be an EPS bearer. The bearer may be a dedicated bearer. The mobility node may be a MME, a S4-SGSN, an ePDG, or a TWAN. The method comprises at least some of the following steps to be performed by the mobility node 105, 1305, which steps may be performed in any suitable order than described below:

(157) Step 2001

(158) This step corresponds to step 1401 in FIG. 16 and step 1501 in FIG. 17. The mobility node 105, 1305 may inform at least one gateway 108, 110, 1305, 1308 of that mobility node 105, 1301 supports handling of bearer mismatch.

(159) Step 2002

(160) This step corresponds to step 1401 in FIG. 16 and step 1501 in FIG. 17. The mobility node 105, 1305 may receive, from at least one gateway 108, 110, 1305, 1308, support information which indicates that it support the handling of bearer mismatch.

(161) Step 2003

(162) This step corresponds to step 1407 in FIG. 16 and step 1508 in FIG. 17. The mobility node 105, 1305 receives information associated with a bearer mismatch from a gateway 108, 110, 1308, 1310.

(163) The information associated with the bearer mismatch may indicate at least a bearer which is missing or unknown in a first received modify bearer or modify access bearers request message received by the gateway 108, 110, 1305, 1308.

(164) Step 2004

(165) This step corresponds to step 1408 in FIG. 16. Based on the received information, the mobility node 105, 1305 determines if there is a need for a further action associated with the bearer mismatch.

(166) To perform the method steps shown in FIG. 20 for handling bearers in the communications system 100 the mobility node 105, 1305 may comprise an arrangement as shown in FIG. 21. The bearer may be an EPS bearer. The bearer may be a dedicated bearer. The mobility node may be a MME, a S4-SGSN, an ePDG, or a TWAN.

(167) To perform the method steps shown in FIG. 20 for handling bearers in the communications system 100, the mobility node 105, 1305 is adapted to, e.g. by means of a receiving module 2101, receive information associated with a bearer mismatch from a gateway 108, 110, 1305, 1308. The information associated with the bearer mismatch may indicate at least a bearer which is missing or unknown in a first received modify bearer or modify access bearers request message received by the gateway 108, 110, 1305, 1308. The receiving module 2101 may also be referred to as a receiving unit, a receiving means, a receiving circuit, means for receiving, input unit etc. The receiving module 2101 may be a receiver, a transceiver etc. The receiving module 2101 may be a wireless receiver of the mobility node 105, 1305 of a wireless or fixed communications system.

(168) The mobility node 105, 1305 is adapted to, e.g. by means of a determining module 2103, based on the received information, determine if there is a need for a further action associated with the bearer mismatch. The determining module 2103 may also be referred to as a determining unit, a determining means, a determining circuit, means for determining etc. The determining module 2103 may be a processor 2105 of the mobility node 105, 1305.

(169) The mobility node 105, 1305 may be further adapted to, e.g. by means of a transmitting module 2108, inform at least one gateway 108, 110, 1305, 1308 of that mobility node 105, 1301 supports handling of bearer mismatch. The transmitting module 2108 may also be referred to as a transmitting unit, a transmitting means, a transmitting circuit, means for transmitting, output unit etc. The transmitting module 2108 may be a transmitter, a transceiver etc. The transmitting module 2108 may be a wireless transmitter of the mobility node 105, 1305 of a wireless or fixed communications system.

(170) The mobility node 105, 1305 may be further adapted to, e.g. by means of the receiving module 2101, receive from at least one gateway 108, 110, 1305, 1308 that it support the handling of bearer mismatch.

(171) In some embodiments, the mobility node 105, 1305 comprises the processor 2105 and a memory 2110. The memory 2110 comprises instructions executable by the processor 2105. The memory 2110 may comprise one or more memory units. The memory 2110 is arranged to be used to store data, received data streams, timer, flag, information about procedures, mismatch information, time intervals, request and response messages, set of bearers, information indicating PDN connections and UE, information associated with bearer mismatch, support information, information indicating a race condition, power level measurements, threshold values, time periods, configurations, schedulings, and applications to perform the methods herein when being executed in the mobility node 105, 1305.

(172) Those skilled in the art will also appreciate that receiving module 2101, the determining module 2103 and the transmitting module 2108, described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processor 2105 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single ASIC, or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a SoC.

(173) In some embodiments, a second computer program may comprise instructions which, when executed on at least one processor, cause the at least one processor to carry out the relevant method steps in FIGS. 16, 17 and 20. A second carrier may comprise the second computer program, and the second carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

(174) The present mechanism for handling bearers in the communications system 100 may be implemented through one or more processors, such as a processor 1903 in the gateway arrangement depicted in FIG. 19 and a processor 2105 in the mobility node arrangement depicted in FIG. 21, together with computer program code for performing the functions of the embodiments herein. The processor may be for example a Digital Signal Processor (DSP), ASIC processor, Field-programmable gate array (FPGA) processor or microprocessor. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into at least one of the gateway 108, 110, 1308, 1310 and the mobility node 105, 1305. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code can furthermore be provided as pure program code on a server and downloaded to at least one of the gateway 108, 110, 1308, 1310 and the mobility node 105, 1305.

(175) Summarized, the method consists of at least the following elements to be implemented in a gateway 1308, 1310 such as e.g. a SGW 108 and a PGW 110: a) detect that a Dedicated Bearer Activation procedure, or a Bearer Deactivation procedure, has been initiated, set a flag, preferably called Dedicated Bearer Activation or Deactivation pending flag, and at the same time, starts a new timer (preferably called racing condition period) from this moment where there is an increased risk for racing conditions; b) while there is an increased risk for racing conditions, i.e. when the timer is still running, handle any received Modify Bearer Request and/or Modify Access Bearers Request messages in the way so that bearers that just have been just created are not unintentionally deleted even when those bearers are not present in the Bearer Context to be modified IE; c) detect when the risk for racing conditions is eliminated or at least significantly reduced, i.e. when the timer expires; d) when the risk for racing conditions is eliminated or at least significantly reduced, handle any received Modify Bearer Request and/or Modify Access Bearers Request messages in “the ordinary” manner, so that information consistency between nodes can be maintained (this is what would be done without the embodiments herein, without considering any risk for racing conditions—the trick is to known when there is such a risk and when there is not).

(176) The embodiments herein provide feedback to the originating node with information on which bearers are missing in a message with one or more bearers that are accepted by the receiving node.

(177) The embodiments herein are not limited to the above described embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the embodiments.

(178) It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It should also be noted that the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements.

(179) The term “configured to” used herein may also be referred to as “arranged to”, “adapted to”, “capable of” or “operative to”.

(180) It should also be emphasised that the steps of the methods defined in the appended claims may, without departing from the embodiments herein, be performed in another order than the order in which they appear in the claims.