WO2004089019A1 - Method of triggering radio network subsystem relocation - Google Patents

Abstract

The present invention discloses a method of triggering radio network subsystem relocation in a mobile communicatio system, where the system includes: the core network communication with the universal terrestrial radio access network (UTRAN); UTRAN consisting of multiple radion network subsystems (RNS) and communicating with one or more UE via Uu interface, each said RNS comprising a radio network controller (RNC) and one or more nodes communicating with said RNC via Iub interface, and each of nodes comprising one or more cells, while RNCs communicating via Iur interface; and said method includes the steps of: determining radio resource control (RRC) connected state that UE located currently; performing the sub-step of triggering service RNC(SRNS) relocating according to RRC-connected state to UE; completing relocatio of SRNS under different RRC-connected state. In accordance to the present invention, it is optimized systematics resource of UTRAN, and may reduce or dispel interrupt of user’s service stream for real time service transmission caused during SRNS’s relocation in prior art, and can rais the radio resource utilization ratio of communication system at the same time.

Description

 Method for triggering relocation of wireless network subsystem

 The invention relates to a method for triggering a service radio network controller to initiate a service radio network subsystem relocation process in a universal terrestrial radio access network of a broadband code division multiple access system. Background technique

 笫 In the Wideband Code Division Multiple Access (WCDMA) system of the 3rd Generation Partnership Project (3GPP), in order to support the mobility of user equipment (UE) in the Universal Terrestrial Radio Access Network (UTRAN), a serving wireless network subsystem (SR S) is defined. ). This process enables the UTRAN to transfer the UE-activated radio resource control (RRC) connection from the source radio network controller (RNC) or service RNC (SRNC) to the destination RNC (or DRNC), thereby optimizing the system resources of the UTRAN.

 In the universal mobile communication system (UMTS) network system structure shown in FIG. 1, the core network is connected to the UTRAN through an Iu interface, and the UTRAN is connected to the UE through a Uu interface. Figure 2 further shows the network structure of UTRAN. Among them, UTRAN is composed of various wireless network subsystems (RSs), which are connected to the core network through Iu interfaces, and different RNSs are connected through Iur interfaces. An RNS is connected by one RNC to one or more Node Bs (Node B) through an Iub interface. Node B actually completes the functions of a base station (BTS) in a mobile communication system. A Node B contains one or more cells, and a cell is the basic unit for UE access.

Figure 3 shows the two cases of UE and UTRAN connection. One scenario is that one or more cells communicating with the UE are controlled by one RNC, as shown in Figure 3 (a). Another scenario is that at least one cell communicating with the UE is called a destination by another RNCC. RNC (DRNC), while serving RNC (SRNC) can include A cell with or without communication with the UE is shown in FIG. 3 (b). In this case, the DRNC mainly provides the wireless link, and the user upper-layer protocol associated with the UE is still mainly completed by the SRNC, and the communication with the core network (CN) associated with the UE still passes through the SRNC and the Iu interface of the core network.

 When the SRNC no longer controls any cell currently communicating with the UE, as shown in FIG. 4 (a), the SRNC still controls the communication with the UE through the lur interface, for example, many problems occur: for example, the bandwidth resource of the lur is occupied This increases the delay caused by the route passing through the lur, reduces the reliability of the system, and so on. Therefore, the SRNS relocation process is introduced in the WCDMA system to optimize the system resources of UTRAN. As shown in Figure 4 (b), after the SRNS relocation process, the original DRNC becomes a new SRNC, and the resources occupied by the original SRNC associated with the UE are released.

 The SRNS relocation process is related to both the core network and UTRAN, because it changes both the Iu interface and the SRNC. For UTRAN, it does not change the existing radio resources associated with the UE, but instead changes the existing radio resources associated with the UE. The upper-layer protocol entity of the user plane associated with the UE is switched from the original SRNC to the new SRNC (that is, the original DRNC). In UTRAN, the SRNS relocation process is jointly completed by the SRNC and the DRNC, and the decision whether to execute the SRNS relocation process is completed by the SRNC, and it is also the SRNC that first initiates the SRNS relocation process.

 FIG. 5 schematically illustrates the signaling flow of SRNS relocation, where:

1. The SRNC sends a Radio Access Network Application Part (RANAP) message-a "Relocation Required" message to the CN;

 2. In response to this RANAP message, the CN sends a RANAP message-a "Relocation Request" message to the destination RNC;

 3. For this "relocation request" message, the access link control protocol (ALCAP) signaling establishes the Iu transmission link between the RNC and the CN;

4. The destination RNC confirms the "relocation request" and sends a RANAP to the CN Message-"Relocation Request Acknowledge";

5. The CN sends a Wireless Network System Application Part (RNSAP) message-"Relocation Command" to the SRNC according to the confirmation;

 6. After receiving the "relocation command", the SRNC sends an RNSAP message-"Relocation Commit" to the destination RNC;

 7. Through the GPRS Tunneling Protocol User Plane (GTP-U) signaling, the SRNC sends a "Data Forwarding" message to the destination RNC;

 8. Next, the destination RNC sends a RANAP message to the CN-"Relocation Detect";

 9. The target RNC also sends to the UE an RRC message carried in a dedicated control channel (DCCH)-either "UTRAN Mobility Information", or "Cell Update Confirm", or "User Registration area update confirmation (URA Update Confirm) ";

 10. The UE recognizes the above message and sends a corresponding RRC message carried by the DCCH to the destination R C;

 11. Purpose The RNC sends a RANAP message to the CN-"Relocation Complete";

 12. The CN then sends a RANAP message to the SRNC-"Iu link resource release command (In Release Command)";

 13. ALCAP releases the Iu transmission link;

 14. The SRNC sends a RANAP message to the CN-"Iu Transmission Link Release Complete (In Release Complete)", and reports to the CN that the Iu transmission link release is complete.

It should be noted here that the signaling step 9 shown in the figure may use three different RRC messages: If it is a separate SRNS relocation process, use "UTRAN mobility information", if it is a SRNS relocation process caused by a cell update , Use "cell update confirmation", if it is a user registration area (URA) update For the SRNS relocation process, "URA Update Confirmation" is used.

 For further description of the SRNS relocation signaling process, please refer to 3GPP's TS23.060, TR25.931 and other documents, and for the various messages and processes involved, please refer to 3GPP's TS25.413, TS25.423, TS25.331 And other agreements.

 In UTRAN of WCDMA, the UE is in idle mode after powering on and camping on the cell. At this time, the UE can receive system information and cell broadcast messages, and monitor paging from the core network. When the UE responds to a page or initiates a call, the UE must establish a RRC connection with the UTRAN through a series of signaling procedures and enter the RRC connection mode. For the specific signaling process of RRC connection establishment, please refer to 3GPP's TR25.931, TS25.331 and other protocols. When the UE is in the RRC connection mode, the RRC layer has four possible states: Cell-DCH, Cell-FACH, Cell-PCH, and TOA-PCH.

 In the Cell-DCH state, the UE has a dedicated physical channel (corresponding to one or more dedicated transmission channels DCH), and a cell having a physical link with the UE becomes an activated cell. All activated cells constitute the UE's activation set. When the number of active sets is equal to or greater than 2, the RNC will be responsible for the uplink macro diversity set and the downlink allocation. In this state, the user mask of the Iur interface between SRNC and DRNC has an active DCH data frame link for transmitting DCH data frames. At the same time, in this state, the system usually updates the active set of the UE through the soft handover process. In WCDMA, another set of cells associated with the soft handover process is called the monitoring set. It is a UTRAN-determined UE. The set of cells measured and reported, the determination of this set depends on the handover algorithm used.

In the Cell_FACH state, the system does not allocate any dedicated physical channel to the UE, however, the UE can use the common (transmission) channel random access channel (RACH) (uplink) and forward access channel (FACH) (downlink) to transmit low activity User data. In this state, the user plane of the Iur interface has an active common transmission channel data frame link for transmitting data frames of the common transmission channel. In this state, UTRAN completes mobility management for the UE through a cell update procedure. In the Cell-PCH state, the system does not assign any active physical channel to the UE. At this time, UTRAN completes the mobility management of the UE through the cell update process, thereby obtaining the location information of the UE at the cell level. The UE can receive the information by monitoring the PCH System page. In this state, the user plane of the Iur interface is usually assigned a data frame link of a public transport channel that has not been activated, which can speed up the process of the UE switching from the Cell-PCH state to the Cell-FACH state.

 In the URA-PCH state, the system does not allocate any activated physical channel to the UE. At this time, UTRAN completes the mobility management of the UE through the URA update process, thereby obtaining the position information of the UE at the URA level. The UE can receive by monitoring the PCH System page. In this state, the user plane of the Iur interface usually does not allocate any public transmission channel data frame links.

 For the detailed description of the RRC connection status above, please refer to 3GPP's TS25.331 and other protocols; for the detailed description of the data frame protocol on the user interface of the Iur interface, please refer to 3GPP's TS25.425, TS25.427 and other protocols. Summary of the Invention

 As mentioned earlier, SRNS relocation can optimize the system resources of UTRAN and increase the reliability of the system. However, according to the SRNS relocation process described above and described in TS23.060, TR25.931, etc., it can be known that: for real-time services, the SRNS relocation process will cause a period of interruption in user traffic, and for non-real-time high-reliability services, SRNS The relocation process needs to perform the process of restoring the downlink N-PDU (network protocol data unit) data of the GTP-U (User Plane GPRS Tunneling Protocol) tunnel through the Iu interface of SRNC and DRNC. This process requires the comparison of SRNC and DR C. Large storage space may cause congestion, and it also increases the retransmission of the RLC (radio link control) layer, which indirectly increases the consumption of wireless resources.

To solve the above problems in the prior art, the present invention proposes a trigger method for SRNS relocation. A method for triggering a relocation of a wireless network subsystem in a mobile communication system according to the present invention, wherein the mobile communication system includes: a core network, which communicates with a universal terrestrial radio access network (UTRAN) through a III interface; and the UTRAN It is composed of multiple wireless network systems (RNS) and communicates with one or more user equipments through a Vu interface.

(UE) communication, each RNS includes a radio network controller (RNC), and one or more nodes that communicate with the RNC through an Iub interface, each node includes one or more cells, and between the RNCs Then communicating through an Iur interface; the method includes the steps of: determining an RRC-connection state where the UE is currently located; and performing a triggered service RNS according to a radio resource control (RRC) connection state where the UE is currently located

(SRNS) a sub-step of relocation; complete the relocation of SRNS under different RRC connection states.

 In a preferred embodiment of the present invention, when the current RRC connection status of the UE is Cell-DCH, the sub-steps of triggering SRNS relocation include the following steps: 1) determining whether the SRNC controls the cells in the active set; 2) and A preset trigger condition is compared, and when as long as one of the conditions is satisfied, a trigger SRNS relocation process is performed. In this embodiment, the step of determining whether the SRNC controls the cells in the active set further includes the step of determining whether there is only one destination RNC (DRNC) connected to the SRNC if the SRNC does not control the cells in the active set. .

 According to the second embodiment of the present invention, when the current RRC connection state of the UE is Cell_FACH or CellJPCH, the sub-steps of performing triggering SRNS relocation include the following steps: 1) determining whether the UE moves to a cell controlled by DRNC; 2) When it is determined that the UE has moved to a cell controlled by the DRNC, it is compared with a preset trigger condition, and when only one of the conditions is satisfied, a triggering SRNS relocation process is performed.

In the third preferred embodiment of the present invention, when the current RRC connection state of the UE is URAJPCH, the sub-step of triggering SRNS relocation includes the following steps: In combination with the URA update process, the SRNS relocation process is triggered according to the URA network configuration structure.

 According to the SRNS relocation triggering method of the present invention, system resources of UTRAN can be further optimized, and the interruption of user service flow caused by real-time service transmission during the prior art SRNS relocation process can be reduced, and communication can be improved at the same time. The wireless resource utilization of the system. BRIEF DESCRIPTION OF THE DRAWINGS

 The above and other objects, features, and advantages of the present invention will become easier to understand from the following detailed description in conjunction with the accompanying drawings:

Figure 1 is a schematic diagram of the structure of a traditional UMTS network system;

FIG. 2 is a schematic diagram of a UTRAN network structure of the UMTS shown in FIG. 1; FIG. 3 schematically shows two cases where a UE is connected to the UTRAN;

Figure 4 is a schematic diagram of SRNS relocation;

FIG. 5 is a signaling flowchart of SRNS relocation;

6 is a schematic flowchart of an SRNS relocation triggering method in a Cell-DCH state according to the present invention;

FIG. 7 is a schematic diagram of SRNS relocation trigger judgment in a Cell-DCH state according to the present invention;

8 is a schematic flowchart of an SRNS relocation triggering method in the CellJFACH and Cell-PCH states according to the present invention;

FIG. 9 is a schematic diagram of SRNS relocation trigger judgment in the Cell-FACH and Cell_PCH states according to the present invention;

FIG. 10 is a schematic diagram of a relationship between a UE movement path and a URA update;

Figure 11 is the signaling process for URA update. detailed description Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. According to the foregoing description, when the UE is in the RRC connection mode, the RRC layer has four possible states: Cell_DCH, Cell_FACH, Cell_PCH, URA_PCBL, and the RNS relocation triggering method provided by the present invention, It is related to the RRC connection status of the UE. Hereinafter, how to perform the RNS relocation triggering method of the present invention in different connection states of the RRC connection mode is discussed separately.

(l) SRNS relocation trigger method in Cell_DCH state

The main factors related to the triggering of SR S relocation in the Cell-DCH state are:

(a) Activate the number of cells controlled by the centralized SRNC;

 (b) the number of cells controlled by the SRNC and their priorities;

 (c) Dedicated channel processor load in SRNC / DR C;

 (d) Iu link load of SRNC and Iur link load of SRNC and DRNC;

 (e) The topology of the UTRAN network;

 The priority of the cell in the monitoring set is defined as the number of times that the cell in the neighboring cell list joins the active set within a certain time range (for example, from the time when the UE enters the Cell-DCH state to the current time). This defines a parameter called the active factor:

(1)

 ∑¾

 k = \

Where and / are the size of the entire monitoring set and the number of cells controlled by the SRNC in the monitoring set, respectively, and are the priorities of the cells in the monitoring set. It can be seen that the smaller the active factor, the smaller the probability that the UE re-enters the cell controlled by the SRNC. Here, a threshold of an active factor is introduced. When the active factor is greater than the threshold P th, it indicates that the UE has a higher probability of re-entering the cell controlled by the SRNC, and when the active factor is lower than the threshold p _th , it indicates that the The probability that the UE re-enters the cell controlled by the SRNC is small. It should be noted that, as an illustrative example, Although only one threshold value is taken here, the present invention is also applicable to a case where a multi-level threshold is used. In a common system implementation, the load of the RNC dedicated channel processor and the load of the Iu / Iur link are all monitored in real time, which is mainly used for system access control, operation and maintenance purposes. These measurement parameters usually need to be smoothed by averaging or filtering, and compared with one or more predefined thresholds to generate one or more levels of overload indication.

 Based on the above definitions, Figure 6 shows the implementation steps of the SRNS relocation triggering method in the Cell_DCH state. In step S601, the SRNS relocation triggering method is started. In step S602, the SRNC first determines whether to control the cells in the active set. If the result of the determination is "yes", the SRNS relocation is not required. The process returns to step S601, and the SRNS waits for the next decision; if the judgment result of step S602 If it is "No", relocation of the SRNS may be required. At this time, in step S603, the SRNS starts a timer T01. After that, the process proceeds to step S604. At step S604, it is further determined whether only one DRNC is connected to the SRNC. If the judgment result of step S604 is "YES", the step proceeds to step S605 to perform a condition judgment as shown in Fig. 7 (this judgment is described in detail below with reference to Fig. 7). If the judgment result of step S604 is "no" ", Then proceed to step S606, and in step S606, further determine whether there are any cells controlled by SRNC joining the active set? If the result of the determination in step S606 is "YES", the timer T01 is reset, and the next SRNS relocation triggers the judgment process. If the determination result in step S606 is "No", the determination in step S604 is performed again. In addition, after the condition judgment of step S605 is completed, the process proceeds to step S607, where it is determined whether at least one of the conditions listed in FIG. 7 is satisfied. If the judgment result of step S607 is "YES", then The SRNS relocation process is triggered, otherwise, the process proceeds to step S606.

In this embodiment of the present invention, when the SRNC no longer controls any cell in the active set (the judgment result of step S602 is "No"), a timer T01 is started, and when an SRNC-controlled cell joins the active set (step S606) The judgment result is "Yes"), reset the timer T01, and apply this timer to prevent the SRNS relocation from triggering back and forth.

In the present invention, as an exemplary example, corresponding to two cases where the active factor is lower than and higher than the threshold 7 _th , respectively, two thresholds T01_Timeoutl and T01_Timeout2 of the timer T01 are defined. Among them, the threshold T01- Timeoutl is smaller than the threshold T01- Timeout2.

 Prior to the reset of T01, preferably if only one DR C is connected to the SRNC, SRNS relocation needs to be performed when one of the following conditions is met. Figure 7 lists in detail the conditions for starting the execution of the SRNS relocation trigger conditions. :

 1) the activity factor p is lower than a predetermined threshold and the timer T01 exceeds a predetermined value T01 Timeoutl;

 2) the activity factor p is higher than a predetermined threshold and the timer T01 exceeds a predetermined value T01_Timeout2;

 3) the dedicated channel processor in the SRNC is overloaded, and the dedicated channel processor in the DRNC is not overloaded;

 4) the lur link between the SRNC and the DRNC is overloaded;

 5) The Iu link of the SRNC is overloaded, and the Iu link of the DRNC is not overloaded;

 6) If it is judged by the handover algorithm unit, the UE needs to be handed over to a third RNC, and the RNC has a current DRNC and no available lur link with the current SRNC (such as the link is overloaded or has a topology structure) (There are no reasons, etc.), in order to avoid direct hard handover from SRNC to this RC, SRNS relocation must be performed before handover.

It should be noted here that the present invention preferably triggers SRNS relocation under the condition that "only one DRNC is connected to the SRNC", because when there are multiple DRNCs, the DCH data frame link of the lur interface is not established between them. Therefore, preferably, in order to perform SRNS relocation, only cells in the active set that belong to a certain DRNC control are retained, and other cells in the active set are deleted to avoid lowering the wireless interface. Performance.

 Except for the SRNS relocation that occurs when the UE is in the macro-diversity state shown in Figure 4, when the handover algorithm unit indicates that a cross-RNC handover needs to be performed, and there is no available Iur link between the two RCs (such as the link is overloaded or extended) (There is no simple structure, etc.), you need to perform a composite process of hard handover and SRNS relocation. Refer to TR25.931 for the signaling flow of the merge process of hard handover and SRNS relocation. (2) The method for triggering SRNS relocation in the Cell_FACH and Cell JPCH states is as described above. When the UE is in the Cell_FACH or Cell_PCH state, the UTRAN completes the mobility management of the UE through the cell update process, thereby obtaining the UE's Location information at the cell level. When the UE needs to perform cell update across the RNC, there are usually two implementation methods: cell update through the Iur interface, or cell update accompanied by the SRNS relocation process. Specific signaling procedures can refer to documents such as TR25.931. In the cross-RC cell update process, the cell update process through the Iur interface is more simple and effective than the cell update process accompanied by SRNS relocation. Therefore, the cell update process accompanied by SRNS relocation should be triggered at a lower frequency. .

 In addition, while performing SRNS relocation to optimize system resources, the cell update process accompanying SRNS relocation has higher signaling efficiency than performing cell update and SRNS relocation separately. Therefore, preferably, when the UE is in a CeIl_FACH or Cell-PCH state, the SRNS relocation is performed in combination with the cell update process.

In addition, when the UE is in the Cell_FACH state and the currently camping cell does not belong to the SRNC control, if the UE will switch to the Cell_DCH state, preferably, the SRNS relocation is performed first, and then the RJRC state transition is performed. In this way, the disadvantages of low efficiency and occupying unnecessary resources caused by the need to establish the required DCH wireless link on the Iur and Uu interfaces at the same time without performing SRNS relocation can be avoided. In addition, because XJTRAN has location information of the cell at the cell level, the SRNC can use a known UTRAN network topology to analyze. When the SRNC finds that the cell in which the UE currently resides is between a certain cell and the same SR C, The cell controlled by the RNC without the lur interface is temporary. Since the UE may move into the cell controlled by the RNC, the SRS relocation should be performed immediately. (The RNS to which the UE currently resides belongs to the RNC because it is geographically related to the RNC. The controlled RNSs are adjacent to each other, and generally there is a lur interface between them in the network configuration). This is because in the WCDMA of Release99, the cell update process needs to use RNSAP (Wireless Network Subsystem Application Part) signaling of the lur interface control plane. If there is no lur interface, the cell update will fail.

According to the above analysis, the trigger method for SRNS relocation in the Cell-FACH or Cell-PCH state proposed by the present invention is shown in FIG. 8. In FIG. 8, an SRNS relocation triggering method in a Cell-FACH or Cell-PCH state is started in step S801. In step S802, it is first determined whether a cell update has occurred. If the determination result in step S802 is "No", the SRNS relocation trigger is not performed. If the determination result is "YES", the process proceeds to step S803. In step S803, it is determined whether the UE moves to a cell controlled by the DRNC. If the result of the determination in step S803 is "No", the SRNS relocation trigger is not performed, and the process returns to step S801, otherwise, the process proceeds to step S804. In step S804, the timer T02 is started. After that, it proceeds to step S805, where the condition judgment shown in FIG. 9 is performed. After that, the process proceeds to step S806, and it is determined whether at least one condition is satisfied. If the determination result of step S806 is "YES", the SRNS relocation process is triggered in step S808. If the determination result of step S806 is "No", then it is determined whether the UE has moved back to the cell controlled by the SRNC in step S807. For the judgment result of step S807, if it is "No", the process returns to step S805, and the condition judgment is performed again; if the judgment result of step S807 is "yes", the timer T02 is reset, and the next SRNS relocation trigger is performed. . When the UE is in the Cell-FACH or Cell-PCH state, after the latest cell update occurs, if the SRNC finds that the UE moves to a cell controlled by the DRNC, it starts a timer T02. If the UE moves back to the cell controlled by the SRNC, The timer is reset. In the present invention, two thresholds T02_Timeoutl and T02_Timeout2 of the timer T02 are defined, where the threshold T02_Timeoutl is smaller than the threshold T02_Timeout2. SRNS relocation is triggered as long as one of the following conditions is met:

 1) If the timer T02 exceeds a predetermined value T02_Timeoutl, the next cell update across the RNC cell is performed with the cell update process accompanying the SRNS relocation;

 2) If the timer T02 exceeds a predetermined value T02-Timeout2, immediately trigger a cell update process accompanied by SRNS relocation;

 3) If the UE is in the Cell-FACH state, before the timer T02 is reset, if the SRNC decides to switch the UE to the Cell-DCH state, the SRNS relocation process should be triggered before the RRC state transition;

 4) Before the timer T02 is reset, after each cell update occurs, the SRNC can use the known UTRAN network topology and the cell-level location information of the UE. If the SRNC finds that the cell in which the UE currently resides is in the same SRNC as a certain cell The cells controlled by the RNC without an Iur interface between them will trigger SRNS relocation immediately.

 Since the data rate in the Cell-FACH state is relatively low, Iur, Iu, and processor resources are relatively small. For simplicity, the impact of these resources may no longer be considered.

(3) SRNS relocation triggering method in URA_PCH state

When the UE is in the URA_PCH state, UTRAN only has the location information of the UE at the URA level, and the cells in the URA may be controlled by one or more RNCs. Therefore, between the two URA update processes, the UE may already be in another location. A cell controlled by an unknown RNC cannot perform the SRNS relocation procedure. Figure 10 shows such an example. Different shades indicate the cells controlled by different RNCs. In the figure, the UE moves from 4 # cell to the 16 # small cell through the identified path. Take the second URA as an example. In this URA, the UE passes through multiple cells controlled by different RNCs.

 Therefore, when the UE is in the URA-PCH state, the time for determining and triggering the SRNS relocation process can only be during the URA update process, as shown in FIG. 11. Figure 11 shows the signaling process of the URA update across RNCs, that is, the situation where the RNC where the UE currently camps (ie the destination RNC in the figure) is different from the SRNC (for a detailed description of this signaling process, refer to TR25. 931 and other agreements). can be seen:

 1. The UE sends an RRC message-a "URA Update" message carried by the CCCH (Common Control Channel) to the cell to which it currently resides.

RNC (ie new RNC), the message includes information such as information unit u-RNTI (UTRAN radio network temporary identifier), URA update cause (URA update cause), etc .;

 2. After the new RNC receives the RRC message, the new RNC sends an RNSAP message to the SRNC-"Uplink Signalling Transfer Indication". This message includes the new c-RNTI, dR TI, etc. Information, where c-RNTI is a wireless network temporary identifier of the RNC controlling the cell, and d-RNTI is a wireless network temporary identifier of the destination RNC;

 3. After the SRNC receives the RNSAP message, the SRNC determines whether to perform SRNS relocation.

 4. When the SRNC determines that SRNS relocation is needed, the SRNC sends an RNSAP message to the new RNC-"Downlink Signalling Transfer Request";

 5. When the new RNC receives the RNSAP message, it sends an RRC message to the UE, a "URA Update Confirm (URA Update Confirm)".

For URA update across RNCs, when the SRNC receives an RNSAP message from the destination RNC-"Uplink Signalling Transfer Indication", it can know exactly where the current UE camps on. Therefore, after the appropriate judgment, the SRS relocation process can be reliably performed; for the same situation that the RNC to which the UE's current cell belongs is the same as the SRNC, because the RRC message from the UE is "URA Update (URA Update ) Contains the u-RNTI (UTRAN Wireless Network Temporary Identity) information element, and this information element contains the unique identifier to identify the SRNC in UTRAN, so SR C can find that the UE is still located in the cell it controls, so there is no need to perform SRNS reset.

 During the URA update process across RNC, the SRNC determines whether to trigger the SRNS relocation strategy, which depends on the network configuration of the URA. One example is to configure the cell controlled by each RNC, that is, the cell in each RNS is configured as a URA. Then, UTRAN can accurately determine the RNS in which the UE is located. In this case, it can be used in conjunction with Cell-FACH or A similar method is used to trigger SRNS relocation in the Cell-PCH state. If the network configuration allows one URA to cover multiple RS cells, the frequency of URA updates is already low, and within a URA, the UE may have passed through multiple cells controlled by different RNCs. In this case, A simple strategy may be adopted, that is, SRNS relocation is performed in each URA update process across RNCs.

 From the foregoing description, the preferred embodiments of the present invention have been described in detail. To those skilled in the art, the above description is only exemplary, and various modifications can be made according to the present invention without departing from the principle of the present invention.

Claims

A method for triggering a relocation of a wireless network subsystem in a mobile communication system, wherein the mobile communication system comprises: a core network, which communicates with a Universal Terrestrial Radio Access Network (UTRAN) through an Iu interface; and the UTRAN is composed of multiple Each radio network system (RS) constitutes and communicates with one or more user equipment (UE) through a Uu interface, and each RNS includes a radio network controller

(RNC), and one or more nodes that communicate with the RNC through an Iub interface, each node includes one or more cells, and RNCs communicate through an Iur interface; the method includes steps:

 Determine the current radio resource control (RRC) connection status of the UE; perform the sub-step of triggering service RNS (SRNS) relocation according to the current RRC connection status of the UE;

 Complete the relocation of SRNS in different RRC connection states.

 2. The method for triggering relocation of a wireless network subsystem according to claim 1, characterized in that, in the step of determining the RC connection status in which the UE is currently located, the determined RRC connection status comprises: Cell-DCH, Cell-FACH, Cell— PCH, URA— PCH.

 3. The method for triggering a wireless network subsystem relocation according to claim 1 or 2, characterized in that when the current RRC connection state of the UE is Cell-DCH, the sub-step of performing triggering SRNS relocation includes the following steps :

 1) Determine whether SR C controls the cells in the active set;

 2) Compare with a preset trigger condition, and when only one of the conditions is met, execute the trigger SRNS relocation process.

 4. The method for triggering a relocation of a wireless network subsystem according to claim 3, wherein the preset trigger conditions include:

 1) The activity factor is lower than the predetermined threshold and the timer T01 exceeds the predetermined value TOl Timeoutl;

2) Active factor ^ is higher than a predetermined threshold _Pth and timer T01 exceeds a predetermined value T01_Timeout2;

 3) the dedicated channel processor in the SRNC is overloaded, and the dedicated channel processor in the DRNC is not overloaded;

 4) the Iur link between the SRNC and the DRNC is overloaded;

 5) The Iu link of the SRNC is overloaded and the Iu link of the DRNC is not overloaded; 6) The UE needs to be switched to three RCs, and the RNC has the current DRNC and no available Iur link with the current SRNC .

 5. The method for triggering a relocation of a wireless network subsystem according to claim 4, wherein the active factor is defined as: ^^^, where and

J is the size of the entire monitoring set and the number of cells controlled by the SRNC in the monitoring set, and "_; is the priority of the first cell in the monitoring set.

 6. The method for triggering relocation of a wireless network subsystem according to claim 4, characterized in that the timer T01 is started when SRNC no longer controls any cell in the active set, and when a cell controlled by SRNC joins the active set, Reset the timer T01.

 7. The method for triggering relocation of a wireless network subsystem according to claim 3, wherein the step of determining whether the SRNC controls the cells in the active set further comprises: when the SRNC does not control the cells in the active set, determining Whether there is only one destination RNC (DRNC) connected to the SRNC.

 8. The method for triggering a relocation of a wireless network subsystem according to claim 1 or 2, characterized in that when the current RRC connection state of the UE is Cell-FACH or Cell-PCH, the execution of the sub-triggers triggering SRNS relocation The steps include the following steps:

 1) determining whether the UE moves to a cell controlled by the DRNC;

2) When it is determined that UE 巳 moves to a cell controlled by DRNC, The trigger conditions set first are compared, and when as long as one of the conditions is met, the trigger SRNS relocation process is performed.

 9. The method for triggering a relocation of a wireless network subsystem according to claim 8, wherein the preset trigger conditions include:

 1) If the timer T02 exceeds a predetermined value T02__Timeoutl, the next cell update across the RNC cell is performed with the cell update process accompanying the SRNS relocation;

 2) If the timer T02 exceeds a predetermined value T02-Timeout2, the SRNS relocation process is triggered immediately;

 3) If the SRNC decides to switch the UE to the Cell-DCH state, the SRNS relocation process is triggered before the RRC state transition;

 4) If the SRNC finds that the cell in which the UE currently resides and a cell controlled by an RNC that does not have a lur interface with the SRNC, SRNS relocation is triggered immediately.

 10. The method for triggering relocation of a wireless network subsystem according to claim 9, characterized in that the timer T02 is started when the UE moves to a cell controlled by DRNC, and reset when the UE moves back to a cell controlled by SRNC The timer T02.

 11. The method for triggering a wireless network subsystem relocation according to claim 8, characterized in that SRNS relocation is combined with a cell update process.

 12. The method for triggering a relocation of a wireless network subsystem according to claim 8, characterized in that before the UE switches to the Cell-DCH state, perform SRNS relocation, and then perform RRC state transition.

 13. The method for triggering relocation of a wireless network subsystem according to claim 1 or 2, characterized in that when the current RRC connection state of the UE is URA_PCH, the sub-step of performing triggering SRNS relocation includes the following steps:

Combined with the URA update process, triggering according to the URA network configuration structure SR S relocation process.

 14. The method for triggering a relocation of a wireless network subsystem according to claim 1 or 2, wherein the communication system is a broadband code division multiple access communication system.