Method and apparatus for identifying user equipment

ES 2 397 964 T3

DESCRIPTION

Method and device for identifying a user equipment and a device for assigning a temporary identity

Field of the invention

The present invention relates to communication technologies and in particular to a method and apparatus for identifying user equipment (UE) and a method for transmitting and assigning a temporary identifier.

Background of the invention

With the development of the network, in the Third Generation Partnership Project (3GPP), manufacturers are actively researching Long Term Evolution (LTE) / System Architecture Evolution (SAE). As illustrated in Figure 1, the LTE / SAE architecture includes: a Mobility Management Entity (MME) 11, configured to memorize a mobility management context of a UE, for example, user identifier, mobility management status and location information, to manage the Non-Access Stratum signaling (NAS) and to ensure the security of NAS signaling and an SAE Gateway (GW) that includes a Service Gateway (S-GW) 121 and a Packet Data Network (PDN) GW Gateway 122, where the S-Gw and the P-GW are two logical entities that can exist in the same physical entity or in different physical entities.

The S-GW gateway memorizes the context of the UE's user plane, eg, IP address and route information of the UE, and performs legal supervision and routing of packet data. The S11 interface between the S-GW gateway and the MME is responsible for communicating between the MME and the S-GW gateway and exchanging mobility management information and session control information of a UE.

The MME 11 works in conjunction with a Universal-Evolved Terrestrial Radio Access Network (E-UTRAN) to realize the control plane connection through the S1-MME interface. The S-GW gateway works together with the E-UTRAN network to make the user plane connection through the S1-U interface. The MME 11 is connected to the 2G / 3G serving GPRS Support Node (SGSN) via an S3 interface and serves as a mobility control plane anchor between the 3G network and the UE equipment SAE network. The S-GW gateway is connected to the SGSN 2G / 3G network through an S4 interface and serves as an anchor of the mobility user plane between the 3G network and the SAE network of the UE.

The P-GW gateway 122 serves as a user plane anchor for a UE to access PDN, communicates with an external PDN through an SGi reference point, and performs packet routing and forwarding, billing enhancement and rules and packet filtering on the basis of each user. The P-GW gateway 122 is connected to the S-GW gateway 121 through an S5 or S8 interface (in the case of roaming) to transmit the support control information such as support creation, support modification and deletion of support. support and to route the data in packets.

A Policy and Billing Rules Function (PCRF) 13 transmits Quality of Service (QoS) and billing policy control information to the P-GW gateway through an S7 interface.

A concept of Temporary Mobile Subscriber Identifier (TMSI) is involved in the SAE network and the Universal Mobile Telecommunications System (UMTS). In a Circuit Switched (CS) domain, the identifier is known as a TMSI; In a Packet Switched (PS) domain, the identifier is known as a packet TMSI (P-TMSI). The TMSI is designed to prevent a user from being tracked when the user's International Mobile Subscriber Identifier (IMSl) is exposed to an over-the-air interface, which may result in a violation of the user's privacy. Therefore, after the user joins the network, the SGSN or the Mobile Switching Center (MSC) allocate a TMSi or a P-TMSI to a user equipment UE. For example, the SGSN network assigns a P-TMSI to the UE and the MsC assigns a TMSI to the UE. The TMSI is unique in a Location Area (LA) of the UE or the P-TMSI is unique in a Routing Area (RA), where a LA can have several RAs. When the user accesses the network, a TMSI or a P-TMSI can be used as the identifier of the UE. When the user performs downlink search paging, the user can be identified by a TMSI or a P-TMSI. If the UE discovers the search information with the TMSI or P-TMSI of the UE in the search channel, the UE initiates the access.

When the UE accesses a new core network node, if the lu-flex concept is not introduced, the new node looks up the old node to get the context of the UE based on an LAI identifier (LAI) or a LAI identifier. RA (RAI). Due to the existence of the lu-flex, the LAI identifier and the RAI is not sufficient for the search of the old node. Consequently, the function of the TMSI or P-TMSI is further adopted together with LAI / RAI to determine the old node. The lu-flex interface means that there is a 'many-to-many' relationship between the access network devices and the core network devices on the lu interface. For example, one RNC is connected to many SGSNs and one SGSN can access many RNCs. The multiple SGSNs constitute a resource pool. In a resource pool, multiple core network nodes (such as SGSN) are connected to all Radio Access Network (RAN) nodes (such as RNC) in the resource pool. In the traditional mode, however, an access network node is connected to only one central network node.

ES 2 397 964 T3

Also, in the case of lu-flex, the RAN can find the node, which the UE registers based on the information in the TMSI / P-TMSI as detailed below.

The TMSI / P-TMSI includes 0 to 10 configurable bits that can serve as a network resource identifier (NRI). The NRI is used to distinguish different core network nodes in a resource pool. When the UE accesses the cluster for the first time, the RAN node is unable to find the corresponding NAS node through the NAS Node Selection Function (NNSF), thus the RAN node selects a suitable exchange network node in function of principles such as load sharing. After registration with a CN node in the resource pool, when moving in the resource pool, the UE does not change the CN node. The principle is as follows: the core network node, where the UE is registered, assigns a TMSI or a P-TMSI to the UE and the TMSI or P-TMSI transmits an NRI representing the core network node. Thus, when the UE tries to access, the UE sends an initial Direct Transfer (DT) message to the RAN, where the message transmits the TMSI or the P-TMSI. The RAN node selects the previously registered core network node corresponding to the NRI in the received TMSI or P-TMSI. Therefore, the user equipment UE moves within the resource pool, while the core network node remains unchanged. However, when the UE exits the resource pool, the RAN node is unable to find the CN node with the corresponding NRI, the RAN node reselects a new core network node, and the UE moves within the new resource pool, still with the core network node kept unchanged.

The TMSI or P-TMSI above is made up of 32 bits, including several (usually two) bits to distinguish the domain of PS and the domain of CS, 0-10 bits configurable for NRI (0 bit indicates no flexibility), several bits for a reset handle and several other bits. The bits can be assigned adaptively depending on the development of the network.

For example, in a TMSI or P-TMSI, two bits are used to distinguish the TMSI and the P-TMSI, five bits are used as a reset identifier that prevents the assignment of an assigned TMSI caused by the node reset, it is they use seven bits as the NRI and the remaining 18 bits are available for assignment of a UE identifier to each core network node.

In the prior art, a TMSI or a P-TMSI is designed in a resource pool. As illustrated in Figure 2, the resource groupings include: Pool 21, Pool 22, Pool 23, Pool 24, Pool 25, and Pool 26. The NRIs for Pool 21 are 16-20; Pool 22 NRIs are 11-15; the NRI of Pool 23 is 1; Pool 24 NRIs are 6-10; Pool 25's NRIs are 1-5 and Pool 26's NRIs are 11. As depicted in Figure 2, Pool 21, Pool 22, Pool 24 and Pool 25 are assumed to be partially overlapping; Each resource grouping includes five core network nodes, where core network nodes are distinguished with different NRIs; NRI can be reused in non-adjacent clusters because the NAS node selection function or the uniqueness of the UE's TMSI in the search area is not affected. It is assumed that a maximum of one million users can be incorporated into each core network node, there are 12 million users in the overlapping area of ​​the cluster, and there are fewer users in other areas.

In this network, 20 core network nodes are enough to serve 12 million users. The NRI can have five bits (because 2⁵ = 32, so NRI is available to identify 32 core network nodes). The identifiers assigned independently by each node are made up of 21 bits (because 1,000,000 = 2²⁰, so that the NRI is available to identify two million users), two bits are used to distinguish PS domain and CS domain and the remaining 4 bits (32-5-21-2) are used for reset .

The SAE network also involves the design of Flex. Like the previous method, in a resource pool, more than one CN node (such as MME) is connected to all RAN nodes (such as eNodeB, that is, ENB) in the resource pool. When a UE initially enters a resource pool, a RAN node selects a CN node based on the principle of load sharing. In this way, the UE is always anchored in the selected CN node when it moves in the cluster or performs an access. MME and S-GW can be connected with ENB in ​​SAE network, so there are two concepts: MME grouping and S-GW grouping. Cluster overlapping is also allowed in the SAE network. In the SAE network, the MME cluster or the S-GW cluster includes a complete Tracking Area (TA). TA is similar to LA or RA in a UMTS network.

Figure 3 depicts the TMSI assignment in an overlapping MME cluster. In Figure 3, it is assumed that the UE assigns a TA at a certain time. When the UE accesses cluster 1 MME for the first time (eg, UE enters ENB 1), an MME is selected from cluster 1 MME (briefly known as MP 1). While the UE is moving from ENB 1 or ENB 2 or ENB 3, it is not necessary to change the MME. When the UE moves to ENB 4, because there is no interface between ENB 4 and the MME in the source MP 1 (ENB 4 belongs to MP 2 only), it is necessary to reselect the MME in the MP 2. In the Figure 3 ENB 2 and ENB 3 belong to two groupings of MME. That is, ENB 2 is connected to each MME of the two clusters through an interface and ENB 3 is connected to each MME of the two clusters through an interface. Therefore, ENB 2 and ENB 3 are the overlap part between MME cluster 1 and MME cluster 2. Advantages of overlap are: when UE returns from ENB 4 to ENB 3, because ENB 3 is connected with MME cluster 2 , it is not necessary to reselect the MME. The reselection of the MME is not required until the UE accesses ENB 1. That is, the overlap avoids the known effect of 'ping-pong' (that is, the reassignment of ping-pong

ES 2 397 964 T3 of the MME). As long as there is no interface between ENB 3 and MME cluster 2, when the UE moves between ENB 3 and ENB 4 back and forth, a ping-pong effect is started.

For the TA concept, the SAE network allows to assign more than one TA to the UE, which is different from a UMTS network; In a UMTS network, only one LA or RA can be assigned to a UE user equipment. Thus, if the UE in the above figure is registered with the grouping and the assigned TA includes TA 1 and TA 2, no update needs to be initiated when the UE moves between ENB 1 and ENB 2 alternately. That is, no update needs to be initiated when the UE moves within the assigned TAs.

In the prior art, NRIs in other resource pools need to be considered when a core network node adds or modifies an NRI in a resource pool. Thus, the assignment of an NRI is complex.

3GPP TSG-RAN WG3 # 53 R3-061194 discloses an SAE / LTE identity, more detailed proposals are made on how identities are assigned and used. The following table proposes some SAE / LTE identities taken into account in the assumption of section 2 (see page 2 to page 4).

3GPP TS 23.003 V7.4.0 discloses a TMSI structure, TMSI consists of 4 octets. It can be encoded using a full hexadecimal representation. In order to avoid a double TMSI assignment after a reset of an assignment node, some part of the TMSI can be related to the time it was assigned or contain a bit field that is changed when the assignment node is assigned. has recovered since the restart (see chapter 2.4 on page 12).

Summary of the invention

Aspects of the present invention provide a method and apparatus for identifying a UE user equipment in an evolved network, as defined in claims 1 and 9. A resource pool identifier, poolID, is set to a System Architecture Temporary-Evolved Mobile Subscriber Identity, SAE-TMSI, as defined in claims 1 and 9, to speed up update pre-processing for an access device and to simplify the configuration of network resources performed by the operator.

Aspects of the present invention also disclose an MME in an evolved network, as defined in claim 11.

Brief description of the drawings

Figure 1 represents a structure of an LTE / SAE network in the prior art;

Figure 2 illustrates how to design a TMSI / P-TMSI in a resource pool in the prior art;

Figure 3 depicts the assignment of a TMSI in an overlapping MME cluster in the prior art;

Figure 4 is a flow chart of a method for identifying a UE user equipment in an SAE network according to an embodiment of the present invention;

Figure 5 represents a flow chart of establishing a pool-ID that is not unique in a PLMN according to an embodiment of the present invention;

Figure 6 is a reselection flow diagram of an MME in accordance with an embodiment of the present invention;

Figure 7 is a flow chart of the first instance of reassignment application of an SAE-TMSI according to an embodiment of the present invention;

Figure 8 is a flow chart of the second instance of reassignment application of an SAE-TMSI according to an embodiment of the present invention;

Figure 9 is a flow chart of the third instance of reassignment application of an SAE-TMSI according to an embodiment of the present invention;

Figure 10 is a transmission flow diagram of an SAE-TMSI according to an embodiment of the present invention;

Figure 11 is a flow chart of assigning a SAE-TMSI according to an embodiment of the present invention;

Figure 12 is a signaling flow diagram of the method for assigning an SAE-TMSI as depicted in Figure 11;

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Figure 13 is a flow chart of a method for receiving and transmitting information based on an SAE-TMSI according to an embodiment of the present invention;

Figure 14 represents a structure of an apparatus for identifying a UE of an SAE network according to an embodiment of the present invention and

Figure 15 represents a structure of an MME in an SAE network according to an embodiment of the present invention.

Detailed description of the invention

The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Figure 4 is a flow chart of a method for identifying a UE in an SAE network according to an embodiment of the present invention. As indicated in Figure 4, the method comprises:

Step 401: A SAE-TMSI is received, where the SAE-TMSI is assigned to a UE that accesses the SAE network and the SAE-TMSI includes at least: a pool-ID identifier, an MME-ID identifier and a UE temporary identifier.

In the access process, a new SAE-TMSI is assigned to the UE. In general, the assignment of a new SAE-TMSI to the UE usually happens in the following operational scenarios: the UE accesses the network for the first time or the UE enters a new cluster from another cluster or the UE initiates a process location update and the network decides to assign a new SAE-TMSI.

Step 402: The SAE-TMSI is used to temporarily identify the UE accessing the SAE network.

That is, a pool-ID identifier, an MME-ID, and a temporary UE identifier are added in the SAE-TMSI in an embodiment of the present invention. The pool-ID is an identifier configured for pooling and can be unique or non-unique in a public land mobile network (PLMN). However, no duplicate pool-ID of the adjacent pool with an overlapping part is allowed. The preferred embodiment is: the pool-ID set in the adjacent pool, without an overlap part, is also unique; the identifier MME-ID is the identifier of the MME in the cluster and is unique in the cluster; the temporary identifier ID of the UE is a unique identifier available from each MME to be assigned to the UE user equipment.

Preferably, in this embodiment, a restart-ID can be added in the SAE-TMSI. That is, an SAE-TMSI includes: a pool-ID identifier, an MME-ID identifier, a temporary UE identifier, and a restart-ID identifier. The established mode of establishment is that said identifiers IDs are added, sequentially, in the SAE-TMSI in the manner previously described. The restart-ID prevents reassignment of an identifier on restart of the MME. The restart-ID can be increased or decreased based on the number of restart times and can support a temporary value.

Preferably, in this embodiment, an identifier to distinguish the types of communication systems can be added in the SAE-TMSI. For example, the identifier differentiates between different systems such as UMTS and SAE. That is, a SAE-TMSI includes: pool-ID, MME-ID, a temporary UE ID and an identifier to distinguish UMTS and SAE and optionally, an identifier to differentiate between another system and the SAE system. The preferred mode of operational setup is that the above identifiers are added, sequentially, in the SAETMSI in the manner described above. The bits for PS / CS can be multiplexed to the identifier that identifies the UMTS system or SAE system or other system, when the number of bits of the SAE-TMSI is the same as that of the TMSI / P-TMSI (that is, 32 bits). For example, 00/01 represents CS, 10 represents SAE, and 11 represents PS.

Preferably, in this embodiment, a restart-ID and an identifier to identify the UMTS / SAE (or other system) can be added in the SAE-TMSI together. That is, a SAE-TMSI includes: a pool-ID identifier, an MME-ID identifier, a temporary UE identifier, a restart-ID identifier, and an identifier to identify the UMTS / SAE (or other system). The preferred mode of operational setup is that the above identifiers are added, sequentially, into the SAE-TMSI in the manner described above.

Preferably, the pool-ID can support a PLMN-ID. That is, the pool-ID is made up of a Mobile Country Code (MCC), a Mobile Network Code (MNC) and an internal pool identifier of the PLMN. The length of an identifier involved in this embodiment is configurable based on actual network conditions. However, the SAE-TMSI design is not limited to the above-disclosed mode and other suitable design modes are also applicable.

In this embodiment, a pool-ID identifier, an MME-ID and a temporary UE identifier are added in an SAE-TMSI and optionally, a SAE-TMSI also includes a restart-ID identifier and / or a

ES 2 397 964 T3 identifier to identify a UMTS / SAE (or other system). The advantages of using an SAE-TMSI are described below, assuming that an SAE-TMSI includes a pool-ID, an MME-ID, and a temporary UE identifier.

The SAE-TMSI includes a pool-ID identifier. An MME-ID can be configured within the cluster independently, regardless of the MME configuration in the adjacent cluster. This is different from the situation in the prior art. In the prior art (as indicated in Figure 2), in the four adjacent clusters, it is not allowed to assign the same NRI. The NRI is equivalent to the MME-ID in this embodiment. Since they are in different networks (the NRI is in the UMTS and the MME-ID is in the SAE), having different names. If the same NRI is assigned, it is possible for the same TMSI / P-TMSI to be assigned to multiple UEs in the overlap area, leading to confusion and failure to locate the proper UE. That is, in the prior art, when adding, modifying or deleting an NRI configured by the core network node, it is necessary to consider the conditions of other adjacent clusters and avoid duplicate NRIs. After the establishment of the NRI of a core network node, it is necessary to notify the other clusters in order to avoid duplicate NRIs. In other words, in the prior art, when adding, modifying or deleting an NRI of a core network node for an access UE in a cluster, it is necessary to consider the conditions of other adjacent clusters and avoid NRIs duplicates. When assigning an NRI to an access UE, it is necessary to notify other clusters and avoid duplicate NRIs in adjacent clusters. Furthermore, when mobile user accesses a network in the prior art, it is necessary to traverse all network resource identifiers, thus resulting in complicated processing, low processing speed, and low user satisfaction.

In this embodiment, a pool-ID is configured in the pool and the pool-ID set for the adjacent pool is different. Therefore, at the time of adding, modifying, or deleting an MME node and setting an MME-ID within a cluster, the MME-ID can be set in the cluster independently, without the need for consider conditions of other clusters as long as there is no duplicate MME-ID in this cluster. That is, in this embodiment, since a pool-ID is configured in the pool, it is not necessary to consider the configuration of the adjacent pool when configuring the MME in this pool.

In this embodiment, when the UE accesses the ENB, the access request transmits an SAE-TMSI that includes at least: a pool-ID identifier, an MME-ID identifier and a temporary UE-ID identifier. After receiving the SAE-TMSI, the ENB determines, based on the pool-ID in the SAE-TMSI, which pool the UE accesses. If the configuration of this pool-ID exists in the current pool, the ENB selects the corresponding MME based on the MME-ID identifier and selects this MME for the UE, thereby performing the UE access. If the pool-ID is not configured in the ENB, the ENB can select a new MME directly, without traversing all the NRIs.

For this embodiment, setting a unique pool-ID in the PLMN provides the following benefits.

If there is no duplicate pool-ID in PLMN, the SAE-TMSI is unique in PLMN and the old MME can be searched based on SAE-TMSI. This is so when the UE accesses a new core network entity, the new core network entity being able to search for the old core network entity based on the pool-ID identifier and the MME-ID identifier in the SAE-TMSI of the UE. In the prior art, however, a TAI needs to be considered when searching for the old core network entity accessed by the UE. Therefore, compared to the prior art, this embodiment is easier to implement and saves network resources.

If the pool-ID is unique through PLMN, when the UE accesses the network, it is not necessary to provide the old TAI. For example, the old TAI information does not need to be transmitted in the NAS messages, such as Attach Join Demand and Tracking Area Update Demand (TAU).

However, when the UE accesses the old network, the RAN adds the old LAI / RAI information of the UE in an initial UE message, with a view to identifying the same TMSI / P-TMSI assigned in different location areas and allowing the core network node to uniquely determine the UE based on the TMSI and LAI. In this embodiment, therefore, it is not necessary to add the current TAI of the UE in the initial UE message.

In other words, if the pool-ID in the SAE-TMSI is unique in the PLMN, when the UE accesses the new MME, the new MME obtains information about the address of the old MME from the pool-ID identifier and MME-ID in the SAE-TMSI of the UE or if the pool-ID in the SAE-TMSI is not unique in the PLMN network, the information about the address of the old MME can be obtained based on the old LAI of the equipment UE alone or based on the old LAI and the SAE-TMSI at the same time.

Since the SAE-TMSI in an MME is unique, when the UE joins the network, the identification request sent by the new MME to the old MME to obtain the UE IMSI does not need to transmit the old TAI information. In the case of flexibility, the new MME obtains the address of the old MME through the old TAI and the SAETMSI (if the SAE-TMSI is unique through PLMN, the new MME can obtain the address of the old MME through SAE-TMSI only). If the address obtained by the new MME is not the address of the old real MME, the new MME can forward the identification request to the old real MME through the SAE-TMSI. In the existing UMTS, the

ES 2 397 964 T3 old RAI information needs to be transmitted in the message because the UE needs to be determined based on the old RAI together with the P-TMSI. In SGSN, a duplicate P-TMSI may exist, but the P-TMSI is of course unique in a RAI. That is, when the UE joins the network, the new MME sends a request to the old MME to request an IMSI. Since the new MME has obtained the address of the old MME based on the old TAI and / or SAE-TMSI, the identification request, sent to the old MME, transmits only the SAE-TMSI parameter and no longer needs to transmit the old TAI. If the old MME is the MME previously registered by the UE, the old MME retrieves the IMSI from the UE based on the SAE-TMSI information and sends an identification response that transmits the IMSI to the new MME. If the MME that receives the identification request is not the old real MME of the EU, the MME forwards the message to the old real MME based on the SAE-TMSI and the old MME retrieves the IMSI based on the SAE-TMSI and forwards the IMSI to the new MME. In the existing UMTS system, however, the IMSI needs to be determined based on the SAE-TMSI along with the TAI.

In this embodiment, the SAE-TMSI can be unique at least in the cluster. Due to the TA concept, the UE can register with multiple TAs or with multiple types of TAs. If the list of TAs assigned to the UE is different, the SAE-TMSI needs to be unique in the same TA in the list of TAs assigned to the UE. Therefore, the preferred embodiment of the present invention is that SAE-TMSI is unique in clustering and unique in overlapping clusters. The duplicate SAE-TMSI may exist in the overlap part. However, other suitable modes are also applicable and are not detailed here again.

Figure 5 represents a flow chart of establishing a pool-ID that is not unique in PLMN according to an embodiment of the present invention. As illustrated in Figure 5, six pools exist in an area and a pool-ID identifier is established for each pool, where the pool-ID is not necessarily unique, that is, non-adjacent pools can have the same pool- ID. That is, the pool-ID of the pools numbered 51 to 55 is set to 1; the pool-ID of the pools numbered 53 to 56 is set to 2; the pool-ID of the pool numbered 52 is set to 3; the pool-ID of the pool numbered 54 is set to 4. Thus, the PLMN -ID can be reused in PLMN and the bits are saved. However, in order to prevent duplicate SAE-TMSIs in the overlapping part, no duplicate pool-IDs can be used for overlapping pools. That is, it is acceptable for non-adjacent clusters to have the same SAE-TMSI. This is because the TA list assigned to a UE never crosses different groupings and it is impossible for duplicate SAETMSIs to exist in the same area. In principle, duplicate pool-IDs can be assigned to adjacent pools without any overlap, but such a configuration is not recommended. When an inactive UE moves from one cluster to an adjacent cluster, a TAU process is initiated. If the two pools have the same pool-ID, it is possible for the ENB accessed by the UE to select the MME that has the corresponding MME-ID in the adjacent pool directly, without initiating a new MME selection. Now when both clusters have the MmE-ID in the SAE-TMSI of the UE, no new MME selection is initiated. Therefore, it is preferred if the pool-ID of the 55-numbered pool is set to 5 and the pool-ID of the 56-numbered pool is set to 6, that is, if there is no duplicate pool-ID in PLMN. In this way, a new selection of MME is always started when the UE accesses other clusters.

As indicated in Figure 3 and Figure 5, assuming that the pool-ID of the MME 1 pool is 1 and the pool-ID of the MME 2 pool is 2, according to the technical solution under the embodiment of the In the present invention, the UE accesses ENB 1 when the UE enters cluster 1 for the first time. ENB 1 discovers that the pool-ID in the SAETMSI of the UE is not configured or is not equal to 1 and therefore directly selects a new MME. ENB 1 can select an MME based on principles such as load balancing. When the UE moves to eNb 2 and initiates access, ENB 2 selects the old MME directly based on the pool-ID and the MME-ID in the SAE-TMSI. When the UE moves to ENB 4, a TAU process is started. ENB 4 discovers that none of these pool-IDs is configured (only pool-ID = 2 is configured for ENB 4) and then directly selects a new MME. At the time of changing the MME, the new MME needs to obtain information about the context or identifier of the UE. If the pool-ID of the SAE-TMSI is unique through PLMN, the new MME can obtain the address of the old MME directly based on the pool-ID identifier and the MME-ID in the SAE-TMSI (and optionally , MCC and MNC information, that is, PLMN information). If the pool-ID is not unique via PLMN, the new MME needs to get the address of the old MME based on the old TAI of the UE. In the case of flexibility, the information in the SAE-TMSI needs to be considered together to determine the address of the old MME.

Also, this operational scenario can occur on the network. The same pool-ID is configured for adjacent pools with no overlap area. A UE starts the TAU process when it moves from one pool to an adjacent pool having the same pool-ID. An initial direct transfer message is sent to the RAN (which usually refers to the ENB) and the RAN node selects an MME based on the pool-ID and the MME-ID in the SAE-TMSI of the UE (assuming there is also the MME-ID in the new pool), without initiating a new MME selection, because a TAU request is sent to the MME with the same pool-ID and the same MME-ID (in fact, the MME is the mMe of the new grouping and not the old MME). Another operational scenario can occur: if the same pool-ID is configured for adjacent or non-adjacent pools, the old SAE-TMSI is memorized at the time of separation called detaching. The UE moves to a new cluster after such separation and joins the cluster. A new selection of MME is not initiated, if the pool-ID of the new pool is the same as the pool-ID of the pool from which UE is separated and if the MME-ID in the SAE-TMSI of the UE exists in the new pool . In this case, the MME to be accessed may not be the MME

It is 2 397 964 T3 more suitable and it is convenient to start a new selection of MME. Therefore, a process of reselection of an MME is established to overcome the difficulty of the previous operating scenario. Figure 6 illustrates the detailed process. Figure 6 is a reselection flow diagram of an MME in accordance with an embodiment of the present invention. As indicated in Figure 6, it is possible that the pool-ID and MME-ID of an MME are the same as the pool-ID and MME-ID in the SAE-TMSI, while the MME is actually different. In this case, the process of reselection of the MME is as follows, taking the TAU as an example:

Step 601: The UE sends an initial handoff message to the ENB. The initial download message includes a NAS message and the NAS message includes a TAU request and an SAE-TMSI. In addition, the TAU claim may include a tAi.

Step 602: After receiving the initial direct transfer message, the ENB selects an MME (such as MME 1) whose identifiers pool-ID and MME-ID are the same as those transmitted in the SAE-TMSI.

Step 603: The ENB sends an initial UE message to MME 1. The initial UE message transmits a TAU request.

Step 604: After receiving the TAU request, MME 1 discovers that the MME 1 itself is not the old MME previously accessed by the UE based on the TAI information (in the case of flexibility, the SAE-TMSI in NAS can be considered together to determine the old MME). Therefore, MME 1 can decide to select a new MME and initiate steps 605-607.

Step 605: MME 1 returns a rerouting command to the ENB.

Step 606: After receiving the rerouting order, the ENB reselects a new MME, for example, MME

2.

Step 607: The ENB sends an initial direct transfer message to MME 2.

Step 608: The remaining TAU process is performed. The remaining process is well known to those skilled in the art and is not repeated here again.

In the onboarding process or other processes started in this embodiment the following operational scenario may occur. The selected MME (such as MME 1) is not the old UE MME (the old MME can be determined based on the information in the old UE TAI). The selected MME 1 can initiate the selection of a new MME (such as MME 2). Or, the ENB selects a new MME (such as mMe 2) directly and forwards a Network Access Server (NAS) message to the new MME 2. The selected MME 1 sends a rerouting command message to RAN and RAN selects a new MME 2 and sends the message to the new MME 2. Either the MME 1 selects a new MME 2 and forwards the NAS message to the new MME 2 directly, or the selected MME 1 selects a new mMe 2 and reports the information of the new MME 2 to RAN and RAN initiates access to the new MME 2. The initiation prerequisites of the new MME 2 to send a rerouting command message or to initiate the new MME 2 selection may be: the load of the selected MME 1 exceeds a set threshold and it is not appropriate to support a new UE or the selected MME 1 discovers that the demand is not a real-time sensitive NAS demand such as TAU or Attach. If these prerequisites are not met, the nine selection of MME 2 is necessarily started.

This embodiment can avoid reselection in this way: when the UE accesses the RAN, the UE not only informs the SAE-TMSI, but also informs the old TAI for the RAN node. When the RAN node discovers that the TAI does not belong to this cluster, the RAN node can select a new core network node. That is, the selector of the intra-domain NAS node, in the initial direct transfer message, sent by UE when accessing RAN also transmits a TAI.

Furthermore, in this embodiment, the identifiers IDs in the SAE-TMSI can be configured based on actual network conditions. For example, it is assumed that a cluster is established for each province, the capacity of each MME is 1 million users, a cluster in a province has a maximum of six adjacent clusters and a maximum of 100 million users exist in a province. . The SAE-TMSI can be set as: 21 bits are used for the temporary identifier of the UE (so that each MME is available to at most 2 million users), 3 bits are used for the pool-ID (reusable, available for at most 8 adjacent clusters), each cluster needs 100 MMEs (100 million users / 1 million MMEs) and 7 bits are used for the MME-ID (available at least 128 MMEs). Assuming the SAE-TMSI has 36 bits constantly (the SAE-TMSI is extensible and the composition of the SAE-TMSI is assumed to be SAE-TMSI = pool-ID + MME-ID + UE temporary identifier + reset ID), the Remaining 5 bits can be used for the reset ID identifier.

For example, there are at most 20 million users on the Beijing network. The maximum capacity of each MME is 2.5 million users and each province requires a unique grouping ID. Therefore 6 bits are used for the pool-ID (available for 64 pools, which is sufficient if each province has a unique pool-ID), 22 bits are used

ES 2 397 964 T3 for temporary UE identification (available for 4 million users). There are 8 MMEs in a cluster and 3 or 4 bits are used for the MME-ID (allowing extension). The remaining 36-6-22-4 = 4 bits are available for the start ID.

The example above assumes that the SAE-TMSI is constant and the identifier IDs can be flexibly configured based on network conditions.

Furthermore, in this embodiment, the SAE network reassigns an SAE-TMSI to a UE user equipment when the pre-set reassignment conditions are met.

Figure 7 is a flow chart of the first application instance of reassigning an SAE-TMSI based on an embodiment of the present invention.

The SAE-TMSI is unique in its wide scope and can be kept unchanged over a long period. However, to protect privacy, the SAE-TMSI needs to change periodically and the network can perform SAETMSI reassignment. The reassignment preset conditions can be: reassignment starts after the location is periodically updated for n times or after the MME is changed or after the MME is changed for n times. For example, a counter is designed for the MME. Once the UE accesses the network or updates, the counter is incremented by 1. After the counter reaches threshold n, the SAE-TMSI is reassigned and sent to the UE, while the counter is reset, as detailed below:

Step 701: When the UE accesses the MME, the UE sends a TAU request to the MME.

Step 702: The MME receives the TAU request and records the number of update times by means of a counter. When the counter reaches a threshold, the process continues to step 703.

Step 703: The MME assigns a new SAE-TMSI to the UE and clears the counter.

Step 704: Meanwhile, the MME forwards a TAU accept message to the user. The TAU accept message transmits a new SAE-TMSI.

That is, when the counter of the MME reaches the threshold (for example, the counter is incremented when UE access occurs, the MMEs are changed or the TAU request is sent), the MME assigns a new SAE-TMSI and it sends it to the UE and then the counter is reset.

Figure 8 is a flow diagram of the second instance of reassignment application of an SAE-TMSI according to an embodiment of the present invention. Also, you can set a timer on the network. The SAE-TMSI is reassigned at the end of the timer timeout. If the UE is inactive at the operational end of the timer, the SAE-TMSI can be assigned at the time of UE access to the network or search in the UE network, as detailed below:

Step 801: A timer is started after the MME assigns an SAE-TMSI to the UE. When the timer reaches the preset time limit, the process continues with step 802.

Step 802: The MME sends search information to the UE, that is, it performs the search paging of the UE.

Step 803: The UE sends a service request to the MME, requesting a new SAE-TMSI.

Step 804: The MME assigns a new SAE-TMSI to the UE and performs the timer reset.

Step 805: The MME sends an SAE-TMSI reassignment message to the UE. This message transmits a new SAETMSI.

Step 806: The UE forwards an SAE-TMSI reassignment acceptance message to the MME.

In Figure 8, the timer starts after the MME assigns an SAE-TMSI to the UE. The MME needs to assign a new SAE-TMSI to the UE after the timer expires and sends the new SAE-TMSI to the UE. In the above example, if the UE is idle at the operational end of the timer, the MME performs paging of the UE and assigns a new SAE-TMSI to the UE after the UE accesses the network. If the UE is in active condition, step 805 and step 806 are performed directly and the newly assigned SAE-TMSI is sent to the UE, without the need for search paging of the UE. Alternatively, a new SAE-TMSI is assigned to the UE when the UE accesses the network after the timer runs out. The process is similar to Figure 8, but no search paging occurs.

Figure 9 is a flow chart of the third instance of reassignment application of an SAE-TMSI according to an embodiment of the present invention. The UE maintains the timer or counter whose timer or counter

ES 2 397 964 T3 counter is similar to the one mentioned above. When the timer or counter reaches the threshold, the UE initiates a SAE-TMSI reassignment process. The process is described below.

In Figure 9, the UE itself determines the SAE-TMSI assignment. For example, the UE sets a timer. A TAU request is sent at the end of the timer, requesting the network to reassign an SAE-TMSI. After receiving the TAU request, the network assigns a new SAE-TMSI to the UE and sends the SAE-TMSI to the UE, as detailed below:

Step 901: After the timer expires, the UE sends a TAU request to the MME, requesting reassignment of an SAE-TMSI (ie, step 902).

Step 903: The MME assigns a new SAE-TMSI to the UE and forwards the SAE-TMSI to the UE via a TAU accept message (ie, step 904).

Step 905: The UE sends a complete TAU message to the MME.

Regarding the access network method that the SAE-TMSI identifies, when the UE accesses the RAN in UMTS, the RRC message sent by the UE, when it accesses the RAN, transmits an initial direct transfer message. An intra-domain NAS node selector is supported in the initial direct transfer message and can include a PTMSI. A NAS can also be requested in the initial direct transfer message and transmitted from the UE to the core network directly, eg RAU or Attach demand. The RAU claim or the Attach claim can include a P-TMSI. Therefore, two P-TMSIs exist in the initial direct transfer message. This results in wasted resources for the radio air interface. That is, in UMTS, the RRC message sent by the UE, when the RAN is accessed, carries an initial direct transfer message. The initial direct transfer message conveys an intra-domain NAS node selector which may include a P-TMSI. The initial direct transfer message can also support a NAS. The NAS is broadcast from the UE directly to the core network, eg RAU or Demand Attach. The RAU claim or the Attach claim can include a P-TMSI. Therefore, two P-TMSIs exist in the initial direct transfer message. This results in wasted resources for the radio air interface.

Two solutions are established in this embodiment to avoid the waste of resources produced in the prior art, as described below.

A method for transmitting an SAE-TMSI is disclosed in an embodiment of the present invention. This method is applicable to transmit an SAE-TMSI from a UE to a core network. As illustrated in Figure 10, the method includes:

Step 100: A UE sends an RRC request that transmits an initial direct transfer message to an evolved RAN entity in an SAE network when the UE accesses the SAE network, where the request supports an SAE-TMSI and a message NAS and the NAS message does not transmit any SAE-TMSI.

That is, when the UE accesses an evolved RAN entity, the UE sends an RRC request that transmits an initial handoff message to the evolved RAN entity. This message transmits a SAETMSI and a NAS message. The NAS message (such as Attach Demand and TAU Demand) does not need to transmit the SAETMSI. This is because the core network obtains the SAE-TMSI through the initial UE message and does not need to obtain the SAETMSI through the NAS message.

Step 101: The evolved RAN entity adds the SAE-TMSI in an initial UE message through an S1 interface when the evolved RAN entity establishes a signaling association with an MME through the S1 interface and provides the SAE-TMSI to a core network node via an initial UE message.

That is, the core network node gets the SAE-TMSI through an initial UE message, but not through the NAS message, thus saving the overhead of the SAE-TMSI transmitted in the NAS message again and It reduces the resource overhead of the air interface and the S1 interface.

In other words, in the SAE system in this embodiment, the SAE-TMSI is included in the RRC portion of the initial handoff message, eg, included in the intra-domain NAS node selector. When the RAN node additionally connects to the S1-MME, the SAE-TMSI is added in the S1-AP message. In the prior art, the initial NAS message is transmitted in the RRC message and the S1-AP message and the P-TMSI is presented by the UE to the core network node directly through a NAS message. In this embodiment, however, the SAE-TMSI needs to be presented only once and is transmitted only in the RRC message instead of the NAS message and the UE presents the SAE-TMSI to RAN, where RAN presents it. to the core network node via an initial setup message S1-AP.

As illustrated in Figure 11, another method of assigning a SAE-TMSI according to an embodiment of the present invention comprises the following steps:

ES 2 397 964 T3

Step 110: An SAE-TMSI for allocation is calculated. The SAE-TMSI fulfills the condition that: a hunt group calculated according to the SAE-TMSI is consistent with a hunt group calculated according to an IMSI.

Step 111: At the time of search paging of a UE, the search message transmitted by the SAE-TMSI is sent to an evolved RAN entity, where the search message does not transmit any IMSI.

Step 112: The evolved RAN entity calculates a UE search paging group based on the SAE-TMSI and performs the UE search.

That is, in this embodiment, the SAE-TMSI assigned by the MME to the UE needs to meet this requirement: the calculated hunt group, based on the SAE-TMSI, is consistent with the hunt group calculated based on the IMSI under a certain algorithm. If they are consistent, when the MME delivers a paging message, the paging message sent to RAN needs to transmit only the SAE-TMSI instead of the IMSI and RAN calculates the UE's paging group based on the SAE-TMSI and performs the search for the UE.

In this method, the SAE-TMSI assigned by the MME needs to meet this requirement: the search paging group calculated based on the SAE-TMSI is consistent with the hunt group calculated based on the IMSI under a certain algorithm. If they are consistent, when the MME delivers a paging message in accordance with Discontinuous Reception (DRX) technology, the paging message sent by the MME to RAN needs to transmit only the SAE-TMSI and not the IMSI and RAN calculates the group Search based on SAE-TMSI and the calculated hunt group is consistent with the search paging group calculated based on IMSI. Therefore, it is not necessary to hand over the IMSI to RAN, the radio air interface resource is saved, and you do not need to expose the IMSI to RAN.

The algorithm for calculating the hunt group is not limited. For example, the modulo operation is performed. Assuming the network needs 12 hunt groups, the hunt group for each IMSI is calculated based on (IMSI mod 12) +1. That is, the IMSI is considered as a number, which is divided by 12, and a remainder (from 0 to 11) is obtained after the division. The remainder "0" indicates search paging group 1, remainder 1 indicates search paging group 2, and so on. The algorithm disclosed here is simple. In practice the algorithm is not limited. The specific algorithm is suitable as long as the SAE-TMSI generated by the network fulfills the consistency condition between the hunt group calculated based on the SAE-TMSI under the algorithm and the hunt group calculated based on the IMSI.

As indicated in Figure 12, the process of this embodiment includes:

1. The UE sends an initial direct transfer message for an RRC message for the ENB. The NAS message, transmitted in the initial download message is the Attach request. In order to save resources, this NAS message does not transmit the SAE-TMSI and only the RRC message transmits the SAE-TMSI.

2. After receiving the message, the ENB selects or reselects the MME based on the SAE-TMSI in the RRC. After the new MME is determined, the ENB appends the NAS message and the SAE-TMSI in the initial UE message of the S1-AP message sent to the new MME. In this way, the new MME gets the NAS message and the SAE-TMSI. That is, after receiving the initial direct transfer message from the UE, the ENB sends an initial UE message that transmits an SAE-TMSI and an Attach request to the new MME.

3. This stage is optional. The new MME can send an identification request to the old MME. The identification request transmits an SAE-TMSI (which does not need to transmit the old TAI) as illustrated by the dotted line in Figure 12.

Four. The old MME forwards an identification response to the new MME, as illustrated by the dotted line in Figure 12.

In this embodiment, other steps in the incorporation process are not detailed here again.

A method for receiving and transmitting information, based on an SAE-TMSI, is disclosed in an embodiment of the present invention, as illustrated in Figure 13. In this method, the new MME sends an identification request or a demand for context to the old MME. The identification request or the context request need not convey the old TAI. The method includes the following detailed steps:

Step 131: If the SAE-TMSI is unique in the MME, the new MME sends an identification request or context request that transmits an SAE-TMSI to an old MME in an onboarding process. The aforementioned claim does not convey the old TAI. Now, the new MME sends a UE context request to an old MME in a location update process of an MME. This request transmits an SAE-TMSI, but does not transmit the old TAI.

ES 2 397 964 T3

Step 132: The old MME resolves the SAE-TMSI in the aforementioned request to obtain an address of an old real MME if the old MME is not the old real MME of the UE.

An apparatus for identifying a UE in an SAE network is disclosed in an embodiment of the present invention. As indicated in Figure 14, the structure of the apparatus includes: a receiving unit 141 and a temporary identification unit 142.

The reception unit 141 is configured to receive an SAE-TMSI assigned to the UE that accesses the SAE network, where the SAE-TMSI includes at least: a pool-ID identifier, an MME-ID identifier and a temporary identifier of EU.

The temporary identification unit 142 is configured to use the SAE-TMSI to temporarily identify the UE accessing the SAE network.

The temporary identification unit 142 comprises: a determination sub-unit 1421, a selection sub-unit 1422, and a reselection sub-unit 1423 (illustrated by dotted lines in the Figure).

The determination sub-unit 1421 is configured to: determine if the pool-ID identifier and the MME-ID, in the SAE-TMSI, that is transmitted in the UE's access request are the same as those configured in the pool of current resources and, if the answer is yes, send a positive result to the selection sub-unit 1422 or if not, send a negative result to the reselection unit 1423.

The selection sub-unit 1422 is configured to select an MME for the UE based on the positive result.

The reselection subunit 1423 is configured to select a new MME for the UE based on the negative result or based on the load balancing principle and based on whether the pool-ID identifier, in the SAETMSI, is unique in the PLMN network.

This appliance can be integrated into an evolved RAN entity.

An MME in an SAE network is disclosed in one embodiment of the present invention. As illustrated in Figure 15, the apparatus includes: a temporary identifier allocation unit 151 and / or a temporary identifier reassignment unit 152.

The temporary identifier assignment unit 151 is configured to assign an SAE-TMSI to the UE accessing an SAE network, wherein the SAE-TMSI includes at least: a pool-ID identifier, an MME-ID identifier and a temporary identifier Of United States.

The temporary identifier reassignment unit 152 is configured to reassign an SAE-TMSI to the UE meeting preset reassignment conditions. The temporary identifier reassignment unit 152 includes at least one of the following subunits: a preset threshold reassignment subunit 1521, a timer reassignment subunit 1522, a location update reassignment subunit 1523 and a remapping subunit 1524.

The preset threshold reassignment sub-unit 1521 is configured to reassign an SAE-TMSI to the UE when the update count of the MME reaches a preset threshold.

The timer reassignment sub-unit 1522 is configured to reassign an SAE-TMSI to the UE at the operational end of the timer started after the MME allocates the SAE-TMSI.

The location update reassignment sub-unit 1523 is configured to reassign an SAE-TMSI to the UE after receiving a TAU request that transmits the SAE-TMSI after the operational end of the timer set by the UE.

The reassignment sub-unit 1524 is configured to send a TAU request that transmits an SAE-TMSI or a reassignment request with an SAE-TMSI, when an updated location registered by a UE or a count is received in a unit of time. reaches a preset threshold and to reassign an SAE-TMSI to the UE.

In a preferred embodiment, the temporary identifier allocation unit 151, in this embodiment, can be connected with the reception unit 141 shown in Figure 14 and the preset threshold reassignment sub-unit 1521, the sub - timer reallocation unit 1522, location update reallocation sub-unit 1523 and reallocation sub-unit 1524, in this embodiment, they can be connected to the selection sub-unit 142 or the reselection sub-unit 143 in Figure 14.

ES 2 397 964 T3

In this embodiment, therefore, different identifiers are set in the SAE-TMSI. The SAE-TMSI is added in the pool-lD identifier according to the operational characteristics of the SAE network. The concept of TA uses the multi-TA registration mode where multiple TAs can be assigned to each UE. In order to avoid duplicate SAE-TMSI in TA, the SAE-TMSI needs to be unique in the cluster. Also, no duplicate SAE-TMSI is acceptable in adjacent clusters with some overlap. Therefore, with the clusters being distinguished by the identifier pool-ID, the SAE-TMSI is surely unique in the registered area of ​​the UE. The pool-ID can be unique across the PLMN network. Thus, the SAE-TMSI is unique through PLMN and the new MME can find the old MME through the UE equipment SAE-TMSI to get the UE context, without the need to consider the TAI. Therefore, the UE does not need to send the TAI. However, the pool-ID may be non-unique in PLMN and a duplicate pool-ID is acceptable in pools without any overlap. In order to avoid the failure of the initiation selection of a new MME, it is desirable that the adjacent pools do not have any duplicate pool-IDs. This method saves the bits of the SAE-TMSI, but the new MME needs to consider the TAI in determining the old MME.

The prior technical solution discloses that: different identifiers (including, without limitation: pool-ID, MME-ID and UE temporary identifier) ​​are set in the SAE-TMSI. When the UE accesses the SAE network, the SAE-TMSI is assigned to the UE and the SAE-TMSI is used to temporarily identify the UE accessing the SAE network. In this embodiment, a pool-ID is configured in the SAE-TMSI, which speeds up UE processing and updating when the UE accesses the SAE network, simplifies the network resource configuration for the operator, and improves the user satisfaction. Furthermore, in this embodiment, the sent message can only transmit the SAETMSI and not the old TAI, thereby saving transmission resources.

Although the invention is described through some example embodiments, the invention is not limited to such embodiments. It is apparent to those skilled in this art that modifications and variations can be made to the invention without thereby departing from the scope of protection of the invention. The invention is intended to cover provided modifications and variants that fall within the scope of protection defined by the following claims or their equivalents.