WO2014180511A1

WO2014180511A1 - Method and apparatuses handling control relocation failures

Info

Publication number: WO2014180511A1
Application number: PCT/EP2013/059751
Authority: WO
Inventors: Jing He; Bindhya Vashini Tiwari; Dario Serafino Tonesi
Original assignee: Nokia Siemens Networks Oy
Current assignee: Nokia Solutions and Networks Oy
Priority date: 2013-05-10
Filing date: 2013-05-10
Publication date: 2014-11-13
Anticipated expiration: 2015-11-10

Abstract

A method comprises receiving in an apparatus of a source control node a relocation message from a first core network node, said message comprising information indicating that a resource allocation between a second core network node and a target control node has failed and in response to said message, causing a relocation to be carried out.

Description

METHODS AND APPARATUSES HANDLING CONTROL RELOCATION FAILURES

This disclosure relates to methods, apparatus and computer programs and in particular but not exclusively to methods, apparatus and computer programs for use in the context of changing from a source node to a target node.

A communication system can be seen as a facility that enables communication sessions between two or more nodes such as fixed or mobile devices, machine-type terminals, access nodes such as base stations, servers and so on. A communication system and compatible communicating entities typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. For example, the standards, specifications and related protocols can define the manner how devices shall communicate, how various aspects of communications shall be implemented and how devices for use in the system shall be configured.

A user can access the communication system by means of an appropriate communication device. A communication device of a user is often referred to as user equipment (UE) or terminal. A communication device is provided with an appropriate signal receiving and transmitting arrangement for enabling communications with other parties. Typically a device such as a user equipment is used for enabling receiving and transmission of communications such as speech and content data.

Communications can be carried on wireless carriers. Examples of wireless systems include public land mobile networks (PLMN) such as cellular networks, satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). In wireless systems a communication device provides a transceiver station that can communicate with another communication device such as e.g. a base station of an access network and/or another user equipment. The two directions of communications between a base station and communication devices of users have been conventionally referred to as downlink and uplink. Downlink (DL) can be understood as the direction from the base station to the communication device and uplink (UL) the direction from the communication device to the base station. Radio Network Controilers (RNC) may be provided. Each RNC may control a plurality of base stations. A UE may be relocated from one RNC to another.

According to an aspect, there is provided a method comprising: receiving in an apparatus of a source control node a relocation message from a first core network node, said message comprising information indicating that a resource allocation between a second core network node and a target control node has failed; and in response to said message, causing a relocation to be carried out.

The relocation may comprise relocating a connection between said first core network node and said source control node to between first core network node and said target control node.

The relocation may be started before a failure message is received from said second core network node.

A user equipment may have a first connection via the source control node to the first core network node and a second connection via the source control node to the second core network node.

The first connection may have one or more higher priority bearers and said second connection may comprise one or more lower priority bearers.

One or more of said first and second core network nodes may comprise a circuit switched node and the other of the first and second network nodes comprises a packet switched network node.

The method may comprise causing a relocation request to be sent to at least one of said first and second core network nodes.

The information may comprise a flag.

The information may be provided in an information element.

The information may be provided in a transparent target control node to source control node transparent container.

The relocation may comprise a serving radio network subsystem relocation.

At least one of said source control node and said target control node may comprise a radio network controller.

The method may comprise causing the sending of information to the target control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node. According to another aspect, there is provided a method comprising: determining in an apparatus of a target control node that resource allocation associated with a first core network node has been successful and that resource allocation associated with a second core network node has been unsuccessful, and providing a relocation message comprising information indicating that resource allocation between the second core network node and the target control node has failed.

The method may comprise receiving information from the source control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

One of said first and second core network nodes may comprise a circuit switched node and the other of the first and second network nodes may comprise a packet switched network node.

The information may comprise a flag.

The information may be provided in an information element.

The relocation may comprise a serving radio network subsystem relocation.

According to an aspect, there is provided a method comprising: causing the sending of information from an apparatus of a source control node to a target control node indicating that at least one connection between said source control node and a first core network node has a higher priority than at least one connection between said source control node and a second core network node.

According to an aspect, there is provided a method comprising: receiving information from a source control node in an apparatus of a target control node indicating that at least one connection between said source control node and a first core network node has a higher priority than at least one connection between said source control node and a second core network node. According to another aspect, there is provided an apparatus in a source control node comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive a relocation message from a first core network node, said message comprising information indicating that a resource allocation between a second core network node and a target control node has failed; and in response to said message, cause a relocation to be carried out.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to start the relocation before a failure message is received from said second core network node.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause a relocation request to be sent to at least one of said first and second core network nodes.

The information may comprise a flag.

The information may be provided in an information element.

The relocation may comprise a serving radio network subsystem relocation.

At least one of said source control node and said target control node may comprise a radio network controller. The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause the sending of information to the target control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

According to another aspect, there is provided an apparatus in a target control node, said apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: determine that resource allocation associated with a first core network node has been successful and that resource allocation associated with a second core network node has been unsuccessful, and provide a relocation message comprising information indicating that resource allocation between the second core network node and the target control node has failed.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive information from the source control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

The information may comprise a flag.

The information may be provided in an information element.

The relocation may comprise a serving radio network subsystem relocation. At least one of said source control node and said target control node may comprise a radio network controller.

According to another aspect, there is provided an apparatus in a source control node, said apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: cause the sending of information to a target control node indicating that at least one connection between said source control node and a first core network node has a higher priority than at least one connection between said source control node and a second core network node.

According to another aspect, there is provided an apparatus in a target control node, said apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive information from a source control node in an apparatus of a target control node indicating that at least one connection between said source control node and a first core network node has a higher priority than at least one connection between said source control node and a second core network node.

According to an aspect, there is provided an apparatus in a source control node, said apparatus comprising: means for receiving a relocation message from a first core network node, said message comprising information indicating that a resource allocation between a second core network node and a target control node has failed; and means for causing a relocation to be carried out in response to said message.

The means for causing said relocation may be for causing a relocating of a connection between said first core network node and said source control node to between first core network node and said target control node.

The apparatus may be such that a user equipment has a first connection via the source control node to the first core network node and a second connection via the source control node to the second core network node.

One or more of said first and second core network nodes may comprise a circuit switched node and the other of the first and second network nodes may comprise a packet switched network node. The apparatus may comprise means for causing a relocation request to be sent to at least one of said first and second core network nodes.

The information may comprise a flag.

The information may be provided in an information element.

The relocation may comprise a serving radio network subsystem relocation.

The apparatus may comprise means for causing the sending of information to the target control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

According to another aspect, there is provided an apparatus in a target control node, said apparatus comprising: means for determining node that resource allocation associated with a first core network node has been successful and that resource allocation associated with a second core network node has been unsuccessful, and means for providing a relocation message comprising information indicating that resource allocation between the second core network node and the target control node has failed.

The apparatus may comprise means for receiving information from the source control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

The information may comprise a flag.

The information may be provided in an information element.

The information may be provided in a transparent target control node to source control node transparent container. The relocation may comprise a serving radio network subsystem relocation.

A radio network controller may comprise any of the above apparatus.

A system may comprise a target control node such as discussed above and a source control node such as discussed above.

According to an aspect, there is provided an apparatus in a source control node comprising: causing the sending of to a target control node indicating that at least one connection between said source control node and a first core network node has a higher priority than at least one connection between said source control node and a second core network node.

According to an aspect, there is provided an apparatus in a target control node comprising: receiving information from a source control node indicating that at least one connection between said source control node and a first core network node has a higher priority than at least one connection between said source control node and a second core network node.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

A computer program comprising program code means adapted to perform the methods may also be provided.

Various other aspects and further embodiments are also described in the following detailed description and in the attached claims.

Some embodiments will now be described, by way of example only, with reference to the accompanying figures in which:

Figure 1 shows a schematic diagram of a communication system comprising base stations and communication devices;

Figure 2 shows a schematic diagram of a mobile communication device according to some embodiments;

Figure 3 shows a schematic diagram of a control apparatus according to some embodiments;

Figure 4 shows a current signal flow during UE handover between two RNCs; Figure 5 shows a signal flow of a first scenario of an embodiment during UE handover between two RNCs; and

Figure 6 shows a signal flow of a second scenario of the embodiment during UE handover between two RNCs.

In the following certain exemplifying embodiments are explained with reference to a wireless or mobile communication system serving mobile communication devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 3 to assist in understanding the technology underlying the described examples.

In a wireless communication system mobile communication devices or user equipment (UE) 2 are provided wireless access via at least one base station 3 or similar wireless transmitting and/or receiving node or point. In the schematic arrangement of Figure 1 , base stations 3a and 3b are controlled by an RNC 4a whilst base stations 3c and 3d are controlled by different RNC 4b. In the example which will be discussed later, the RNC 4a which controls base stations 3a and 3b is the source RNC. The other RNC is the target RNC.

It is noted that the radio service area borders or edges are schematically shown for illustration purposes only in Figure 1. It shall also be understood that the sizes and shapes of radio service areas may vary considerably from the shapes of Figure 1. A base station site can provide one or more cells. A base station can also provide a plurality of sectors, for example three radio sectors, each sector providing a cell or a subarea of a cell. All sectors within a cell may be served by the same base station.

The base stations are controlled by the respective RNC. The RNCs are arranged to communicate with a core network 5 which may comprise network entities such as a mobile switching centre (MSC) 10 and a serving GPRS (general packet radio system) support node (SGSN) 12.

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 2. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility, personal data assistant (PDA) provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided with broadcast or multicast data. Non-limiting examples of the content include downloads, television and radio programs, videos, advertisements, various alerts and other information.

The mobile device 2 may receive signals over an air interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 the transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

A wireless communication device can be provided with a Multiple Input / Multiple Output (MIMO) antenna system. MIMO arrangements as such are known. Ml MO systems use multiple antennas at the transmitter and receiver along with advanced digital signal processing to improve link quality and capacity. Although not shown in Figures 1 and 2, multiple antennas can be provided, for example at base stations and mobile stations, and the transceiver apparatus 206 of Figure 2 can provide a plurality of antenna ports. More data can be received and/or sent where there are more antenna elements. A station may comprise an array of multiple antennas. Signalling and muting patterns can be associated with TX antenna numbers or port numbers of MIMO arrangements.

A mobile device is typically provided with at least one data processing entity 201 , at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

Figure 3 shows an example of a control apparatus. The control apparatus may be provided in one or more of a RNC, base station, MSG, SGSN or any other suitable apparatus. The control apparatus 300 comprises at least one memory 301 , at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to at least one other entity. The control apparatus 300 can be configured to execute (in the one or more processors) an appropriate software code (stored in one or more memories) to provide the control functions.

The communication devices 2 may access the communication system based on various access techniques, such as code division multiple access (CDMA), or wideband CDMA (WCDMA). Other non-limiting examples comprise time division multiple access (TDMA), frequency division multiple access (FDMA) and various schemes thereof such as the interleaved frequency division multiple access (IFDMA), single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA), space division multiple access (SDMA) and so on.

An example of wireless communication systems are architectures standardized by the 3rd Generation Partnership Project (3GPP). A latest 3GPP based development is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. The various development stages of the 3GPP LTE specifications are referred to as releases. More recent developments of the LTE are often referred to as LTE Advanced (LTE-A). The LTE employs a mobile architecture known as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN). Base stations of such systems are known as evolved or enhanced Node Bs (eNBs) and may provide E- UTRAN features such as user plane Radio Link Control/Medium Access Control/Physical layer protocol (RLC/MAC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices. Other examples of radio access system include those provided by base stations of systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access). Some embodiments may be provided in the context of WCDMA/HSPA.

A UE involved relocation procedure has been defined in 3GPP specifications, for example in R99, for lu based UE handover between two RNCs (i.e., for handover without an existing lur connection between the RNCs). In case there are CS RAB (circuit switched radio access bearer) and PS RAB (packet switched radio access bearer) in parallel for one UE, the relocation procedure should forward the two lu connections (one for the CS domain via the MSG -UE to MSG, and the other for the PS domain via the SGSN- UE to SGSN) together from source RNC to target RNC

A proposal (R3-122026) has been made which addresses how to handle the handover towards a target CSG (closed subscriber group) cell with an emergency call when the user is not a member of that CSG cell. As a consequence of the agreement, some exceptional conditions and behaviors in the coordination of two domains during relocation have been added to 3GPP TS 25.413 version 9.8.0.

Reference is made to Figure 4 which shows a message flow during a relocation procedure involving two domains according to current proposals. In the arrangement of figure 4, the signal flow between a source RNC 4a, a MSG 10, a SGSN 12 and a target RNC 4b is shown.

In step S1 , a relocation required signal is sent from the source RNC 4a to the MSG 10.

In step S2, a relocation required signal is sent from the source RNC 4a to the SGSN 12. It should be appreciated that steps S1 and S2 can take place in either order or at the same time.

In step S3, the source RNC 4a will start a timer TRaocprep. In the MSG, receipt of the relocation required signal from the RNC 4a causes the MSG to send a relocation request in step S4 to the target RNC 4b. This also triggers in the MSG a starting of a timer TRELocaiioc in step S5.

In step S6, a Timerl is started when the Target RNC receives the first relocation request message from one CN (core network) domain, and it runs until a relocation request message from the second CN domain is received. In this example, the MSG 10 and SGSN are in different core network domains. Thus the timer is started in this example in response to the relocation request of step S4 and stopped in response to the relocation request received in step S7, discussed below.

In step S7, receipt of the relocation required signal from the source RNC in the SGSN will cause the SGSN to send a relocation request to the target RNC.

In step S8, the SGSN will start a timer T_REiocaiioc.

It should be appreciated that steps S5 and S8 can take place in any order or at the same time. Likewise, steps S4 and S7 can take place in either order or at the same time.

In step S9, a relocation request acknowledgement is sent from the target RNC 4b to the MSG 10.

Likewise, in step S10, a relocation request acknowledgement is sent from the target RNC 4b to the SGSN 12. It should be appreciated that steps S9 and S10 can take place in any order or at the same time.

In response to receiving the relocation request acknowledgement in the MSC 10, the MSC 10 in step S1 1 sends a relocation command to the source RNC. It should be appreciated that the receipt of the relocation request acknowledgement starts a TREtoccompiete timer in step S13, in the MSC.

The receipt of the relocation command triggers in step S12 a second timer

Timer2 in the source RNC. In case of coordination of two lu Signaling Connections, this timer is started when the source RNC receives the first relocation command message from one CN domain, and it runs until the relocation command message from the other CN domain is received.

On receipt of the relocation request acknowledgement in the SGSN 12, in step S14, the SGSN will send a relocation command to the source RNC 4a. It should be appreciated that the receipt of the relocation request acknowledgement starts a T_RELoccon*iete timer in step S15, in the SGSN. Some implementation may address the following problems. Firstly if, during relocation, the target RNC receives a relocation request from the MSG and the Number of lu Instances IE (information element) is set to 2, but the target RNC does not receive a relocation request from SGSN while Timer! is running, then the relocation procedure would fail (independently of whether there is an ongoing emergency call procedure or not).

Secondly if the target RNC receives the relocation request message both from the SC and from the SGSN separately while TimeM running and the Number of lu Instances IE is set to 2, then the Target RNC shall initiate the allocation of requested resources. If, however, the resource allocation for one domain fails, the target RNC will reply with a relocation failure message, even if the resource allocation for the other domain (which has an emergency RAB) is successful. This would terminate the relocation procure even if the relocation for the domain with the emergency RAB did not fail.

There has been a proposal for the handling of relocation of two domains when one domain has a high priority RAB (e.g. CS emergency RAB and PS normal RAB). Currently the source RNC shall wait for two relocation command messages from the MSC and the SGSN. After receiving both, a relocation next step in the source RNC can be initiated. Thus the source RNC shall not continue the SRNS (Serving Radio Network Subsystem) relocation unless it has received a relocation command message from all lu signalling connections towards which the Relocation Preparation procedure had been initiated.There has been another proposal for handling of relocation of two domains when one domain with an high priority RAB (e.g. CS emergency RAB and PS normal RAB). It is proposed to consider an exception case in the source RNC when the expected relocation command message from other domain is not received, i.e. the source RNC shall still proceed with the Relocation commit procedure that has the emergency RAB.

In this another proposal, the source RNC can only trigger SRNS relocation after the second timer, Timer2 has expired. As the CS RAB is for an emergency call, waiting a long time in the Source RNC may delay the emergency call handover to the Target RNC. The worsening of radio conditions in the source cell during such a relatively long waiting time may lead to dropping the emergency call. In some embodiments, this latter proposal may be modified to reduce the delay in the source RNC. During the relocation preparation phase, one UE has an lu connection to one CN domain with high priority RABs and the UE also has an lu connection to another CN domain with lower priority RABs. The lower priority RABS may be those used in normal operation. If the resource allocation for RABs with a relatively high priority is successful while the allocation for RABs of the other CN domain failed, some embodiments may reduce waiting delay in the source RNC. For example the source may immediately proceed with relocation for high priority RABs and/or stop the relocation procedure for the other domain before failure response is actually received.

To facilitate a Target RNC to prioritise resource allocation for the high priority RAB of one CN domain over other RABs over other CN domain, a source RNC may send a further indication in the source RNC to target RNC transparent container. This indication is sent to the target RNC which may use this information or use its own algorithm to prioritise RABs of a CN domain when multiple CNs are involved in the relocation. A Target RNC can use such indication also to know that the source RNC is capable of handling successful resource allocation from one CN domain only. This indication may be referred to a prioritising of resource allocation indication in the following. This indication may take the form of a flag or be provided in any other suitable manner. This is marked Flagl in the following Figures.

Relatively high priority may mean that the indicated RABs should be transferred to the Target RNC even when the resource allocation to all RABs in another CN domain failed in the Target RNC (e.g. emergency call RABs in CS domain, or other RABs that operator sets as having a relatively high priority).

Reference is made to Figure 5 which shows a first embodiment. Figure 5 shows a message flow, similar to that shown in Figure 4. It should be appreciated that steps T1 to T6, and T8 may correspond to steps S1 to S6, and S8 respectively of Figure 4.

However, in some embodiments, the source RNC 4a may provide a prioritising of resource allocation indication in the relocation required message in step T1 and the MSG 10 forwards the prioritising of resource allocation indication (Flag 1 ) to Target RNC 4b to set higher priority to RABs of this lu connection over other RABs of another CN domain. Thus the target RNC 4b receives a relocation request message from the MSG with the number of lu instances IE set to 2 in step T4. However, the target RNC does not receive the relocation request message from the SGSN while Timerl is running. This is represented schematically by step T7 with a cross in Figure 5.

In step T9, there is successful resource allocation for RAB for high priority calls like emergency calls. If one RAB included in the relocation request from MSG is for high priority calls like emergency calls, the target RNC shall initiate allocation of the requested resources. If the target RNC receives prioritising of resource allocation indication from the source RNC that higher priority RABs of one CN domain could be prioritized over other RABs of another CN domain, then the target RNC may continue with resource allocation with higher priority RABs of other CN domain, if this is supported.

If resource allocation is successful for the higher priority RAB(s), then in step T10, the target RNC shall generate a relocation request acknowledgement with resource allocation failure information which is sent to the MSG 10. The resource allocation failure information (Flag 2) indicates that the lu signaling connection of the SGSN with the target has failed to be established. This resource allocation failure information may be provided by a flag or by any other suitable indication. This resource allocation failure information may be provided in a target RNC to source RNC Transparent Container IE in the message.

It should be appreciated that step T12 corresponds to step S13 of Figure 4. When the MSG receives the relocation request acknowledgement, the MSG generates a relocation command which is sent to the source RNC in step T11. The target RNC to source RNC transparent container IE is transparently transferred (which contains the resource allocation failure information).

When the source RNC detects the resource allocation failure information in the relocation command, the source RNC does not need to start Timer2 to wait for relocation preparation failure from the SGSN. Instead the SRNS relocation execution is started, in step T13. Since the PS connection was not established, the SRNC can initiate the PS release locally after the CS relocation has been completed.

If the resource allocation of step T9 is unsuccessful, the target RNC will generate a relocation request failure to the MSG, and in that case the relocation procedure is terminated. The MSG sends relocation request failure to the source RNC which ends the relocation of UE to the target RNC.

Reference is made to Figure 6 which shows a second situation. Figure 6 shows a message flow, similar to that shown in Figure 4. It should be appreciated that steps A1 to A8 correspond to steps T1 to T6 and T8 respectively of Figure 5 while step A7 corresponds to step S7 of Figure 4.

The source RNC 4a may provide a prioritising of resource allocation indication (Flag 1) in step A1 and MSG 10 may forward the indication to the target RNC 4b to set a higher priority to RABs of this lu connection over other RABs of another CN domain.

The target RNC receives a relocation request message from the MSG and the SGSN separately (steps A4 and A7) while Timerl is running and the IE Number of lu Instances is set to 2.

The target RNC shall initiate the allocation of requested resources. However, in step A9, the resource allocation for RABs from the SGSN fails but resource allocation to RAB for a priority call from the MSG is successful,

In step A10, the target RNC generates a relocation request acknowledge with a resource allocation failure information (Flag 2) to the SC, which is the CN node with the high priority (e.g. emergency) RAB. The resource allocation failure information indicates one lu connection of SGSN has failed, which is included in the target RNC to Source RNC transparent container IE in the message. The resource allocation failure information may take any suitable form and may for example be in the form of a flag.

The target RNC also generates a relocation request failure towards the SGSN (the CN domain with the normal or lower priority RAB) in step A11.

When the MSC receives the relocation request acknowledge message, the MSC generates a relocation command message including the resource allocation failure information (Flag 2) received from the target RNC. This message is sent in step A12 to the source RNC.

It should be appreciated that step A13 corresponds to step S13.

In step A14, when the source RNC detects the resource allocation failure information (Flag 2) in the relocation command message, the source RNC does not need to start Timer2 to wait for the relocation preparation failure message from the SGSN which is provided in step A15. The SGSN is the CN node with normal or lower priority RABs only. At this point the source RNC can trigger the SRNS Relocation procedure.

It should be appreciated that step A16 corresponds to step S15.

In case no high priority or emergency RABs have been indicated, the target

RNC shall generate a relocation request failure message and send it to the MSG and the SGSN.

Some embodiments may add a flag or other indication in the relocation command message. Some embodiments may use only one flag. Other embodiments may use more than one flag. The information may be indicated by any other suitable mechanism in other embodiments. The flag or other indication may be provided in the relocation request acknowledge message to indicate that all RABs or RABs with a lower priority indicated by the flag have failed in resource allocation in a target RNC. The failed RABs may be related to another CN domain.

When received the relocation command message with the flag or other indication from one CN domain, the source RNC may execute the SRNS Relocation immediately or relatively promptly. The source RNC does not need to wait for the indication about relocation failure from the other CN domain to end the relocation preparation which would complete with the response of the second CN domain. The source RNC may ignore/ discard the ongoing relocation preparation of the other CN domain if a response arrives afterwards. The source RNC may skip waiting for timer expiry and receiving relocation response of other CN domain in order to fasten the relocation procedure and source RNC may proceed further with relocation to target RNC.

The source and target RNCs can be regular RNCs or CSG HNB-GW (home node B gateways) or any other similar entity.

To provide a flag or other indicator in a relocation command message and in the relocation request acknowledge message, it is possible to define one or more IE in these messages or include this flag or indicator into one or more other lEs. For example the flag or indicator may be provided in the target RNC to source RNC transparent container IE and/or another IE. The Target RNC to Source RNC Transparent Container IE is maintained by the RNC without impact to the CN, and Target RNC has to send the Target RNC to Source RNC Transparent Container to source RNC during relocation procedure.

The flag or indicator may take any suitable form. For example, in some embodiments, the flag may have the value of 1 or 0. One value will indicate if RABs related to another CN or the like domain have failed.

In other embodiments, the flag or indicator may provide more information to the source RNC. By way of example one or more of the following information may be provided: do not wait for non-emergency (or non-relatively high priority) connections, wait only x milliseconds/seconds for non-emergency connection relocation response, connections with a lower priority than indicated in the flag are not allowed in network node or in cell, CSG, do not wait for non-member of target CSG cell connection, indication back from target to source RNC may mean that RABs with lower priority than indicated are omitted/did not get any resources in target RNC but the higher RABs do have reservations, indication from source to target RNC may indicate that RAB with priority lower than indicated priority value may be omitted during relocation and still is considered successful, a combination of the examples above or the like.

In some networks, the typical value of TR_BiocPrep is 6 sec and Timerl and Timer2 are 10 sec. Timer2 will be triggered after received one RELOCATION COMMAND from one CN domain. In some embodiments a maximum benefit to save waiting time in the source RNC may be 10 sec.

It should be appreciated that some embodiments have been described in relation to a PS and CS bearers. It should be appreciated that embodiments may be used with any other suitable bearer pairs. In some embodiments, the bearer pairs may be PS and PS bearers or CS and CS bearers. In some embodiments, bearers other than PS and CS bearers may be used.

In some embodiments, there may be more than two bearers which may be transferred from a source to a target node.

In the example shown, the SGSN connection relocation is unsuccessful and the MSG connection relocation is successful. However in other embodiments, the SGSN connection relocation is successful and the MSC connection relocation is unsuccessful. It should be appreciated that in other embodiments, one or more of the SGSN and MSC may be replaced by any other suitable core node. The core nodes may be of the same type or different types.

In case that the target cell is a CSG cell, a UE may not be member of the CSG cell. Then relocation of the higher priority call of the CS domain and normal RABs of PS domain to the target cell will be failed as member checking. One exception has been agreed is that the emergency call should be relocated to target CSG cell even through UE is not member of the CSG cell. Embodiment can be used in this situation to inform the source RNC via the relocation command from the MSC that all normal RABs of the PS domain are failed.

The required data processing apparatus and functions of a controller apparatus, a communication device and any other appropriate apparatus may be provided by means of one or more data processors. The described functions at each end may be provided by separate processors or by an integrated processor. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non-limiting examples. The data processing may be distributed across several data processing modules. A data processor may be provided by means of, for example, at least one chip. Appropriate memory capacity can also be provided in the relevant devices. The memory or memories may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects of the invention may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.

The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the exemplary embodiment of this invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention as defined in the appended claims. Indeed there is a further embodiment comprising a combination of one or more of any of the other embodiments previously discussed.

Claims

1. A method comprising:

receiving in an apparatus of a source control node a relocation message from a first core network node, said message comprising information indicating that a resource allocation between a second core network node and a target control node has failed; and

in response to said message, causing a relocation to be carried out.

2. A method as claimed in claim 1 , wherein said relocation comprises relocating a connection between said first core network node and said source control node to between first core network node and said target control node.

3. A method as claimed in claim 1 or 2, wherein said relocation is started before a failure message is received from said second core network node.

4. A method as claimed in any preceding claim, wherein said a user equipment has a first connection via the source control node to the first core network node and a second connection via the source control node to the second core network node.

5. A method as claimed in any preceding claim comprising causing a relocation request to be sent to at least one of said first and second core network nodes.

6. A method as claimed in any preceding claim, comprising causing the sending of information to the target control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

7. A method comprising: determining in an apparatus of a target control node that resource allocation associated with a first core network node has been successful and that resource allocation associated with a second core network node has been unsuccessful, and

providing a relocation message comprising information indicating that resource allocation between the second core network node and the target control node has failed.

8. A method as claimed in claim 7, comprising receiving information from the source control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

9. A method as claimed in any preceding claim, wherein said first connection has one or more higher priority bearers and said second connection comprises one or more lower priority bearers.

10. A method as claimed in any preceding claim, wherein one of said first and second core network nodes comprises a circuit switched node and the other of the first and second network nodes comprises a packet switched network node.

11. A method as claimed in any preceding claim, wherein information comprises a flag.

12. A method as claimed in any preceding claim, wherein said information is provided in an information element.

13. A method as claimed in any preceding claim wherein said information is provided in a transparent target control node to source control node transparent container.

14. A method as claimed in any preceding claim, wherein said relocation comprises a serving radio network subsystem relocation.

15. A method as claimed in any preceding claim, wherein at least one of said source control node and said target control node comprises a radio network controller.

16. A communication system comprising a source control node and a target control node configured to perform a relocation according to any of claims 1 to15.

17. A computer program product comprising computer executable instructions which when run cause the method of any one of the preceding claims to be performed.

18. An apparatus in a source control node, said apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

receive in an apparatus of a source control node a relocation message from a first core network node, said message comprising information indicating that a resource allocation between a second core network node and a target control node has failed; and

in response to said message, causing a relocation to be carried out.

19. Apparatus as claimed in claim 18, wherein said relocation comprises relocating a connection between said first core network node and said source control node to between first core network node and said target control node.

20. Apparatus as claimed in claim 18 or 19, wherein the at least one memory and the computer code are be configured, with the at least one processor, to cause the apparatus to start said relocation before a failure message is received from said second core network node.

21. Apparatus as claimed in any of claims 18 to 20, wherein said a user equipment has a first connection via the source control node to the first core network node and a second connection via the source control node to the second core network node.

22. Apparatus as claimed in any of claims 18 to 21 , wherein the at least one memory and the computer code are be configured, with the at least one processor, to cause the apparatus to cause a relocation request to be sent to at least one of said first and second core network nodes.

23. Apparatus as claimed in any of claims 18 to 22, wherein the at least one memory and the computer code are be configured, with the at least one processor, to cause the apparatus to cause the sending of information to the target control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

24. An apparatus in a target control node, said apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

determine that resource allocation associated with a first core network node has been successful and that resource allocation associated with a second core network node has been unsuccessful, and

provide a relocation message comprising information indicating that resource allocation between the second core network node and the target control node has failed.

25. Apparatus as claimed in claim 24, wherein the at least one memory and the computer code are configured, with the at least one processor, to cause the apparatus to receive information from the source control node indicating that at least one connection with said first core network node has a higher priority than at least one connection with said second core network node.

26. Apparatus as claimed in any of claims 18 to 25, wherein said first connection has one or more higher priority bearers and said second connection comprises one or more lower priority bearers.

27. Apparatus as claimed in any of claims 18 to 26, wherein one of said first and second core network nodes comprises a circuit switched node and the other of the first and second network nodes comprises a packet switched network node.

28. Apparatus as claimed in any of claims 18 to 27, wherein information comprises a flag.

29. Apparatus as claimed in any of claims 18 to 28, wherein said information is provided in an information element.

30. Apparatus as claimed in any of claims 18 to 29, wherein said information is provided in a transparent target control node to source control node transparent container.

31. Apparatus as claimed in any of claims 18 to 30, wherein said relocation comprises a serving radio network subsystem relocation.