WO2009110718A2

WO2009110718A2 - Method for supporting ue's switching between macro node b and home node b

Info

Publication number: WO2009110718A2
Application number: PCT/KR2009/001022
Authority: WO
Inventors: Hong Wang; Lixiang Xu; Xiaoqiang Li
Original assignee: Samsung Electronics Co., Ltd.; Beijing Samsung Telecom R&D Center
Priority date: 2008-03-06
Filing date: 2009-03-03
Publication date: 2009-09-11
Also published as: CN101527941A; WO2009110718A3

Abstract

A method for supporting UE's switching between a macro Node B cell and a HNB cell is provided in the present invention. It includes the following steps: The HNB sends a configuration parameter request message to an operation control node; the operation control node sends a configuration parameter response message to the HNB, and in such message it contains the information on the MME to which that the HNB is connected; by the HNB's broadcast message, the UE learns about the information on the MME to which the HNB is connected; the UE sends a measuring report message to the macro Node B, and in such message it contains the information on the MME to which the HNB is connected.

Description

METHOD FOR SUPPORTING UE'S SWITCHING BETWEEN MACRO NODE B AND HOME NODE B

The present invention relates to communication field, especially to a method for supporting UE switching between macro cell and Home Node B (HNB) cell.

The system structure of SAE (System architecture evolution) for the universal mobile telecommunication system (UMTS) is illustrated in figure 1. The following is the description on the SAE in Figure 1.

A user Equipment 101 (hereinafter referred to as UE) is the terminal device used to receive data. EUTRAN 102 (Evolved UMTS Terrestrial Radio Access Network) is the radio access network of the LTE SAE. It is composed of the evolved NodeB (ENB), which is responsible for providing an interface through which an LTE mobile phone accesses the radio network. And through an interface S1, the EUTRAN is connected to a mobile phone's mobility management entity (MME) 103 and a user plane entity Serving Gateway 104. The MME 103 is responsible for managing UE's mobile context, session context, and for saving the user information on security. The Serving Gateway 104 primarily provides a function of user plane. The interface S1-MME between the ENB and the MME is responsible for establishing a radio access bearer for the UE, forwarding the messages sent from UE to MME through the wireless access network. The combined function of MME 103 and Serving Gateway 104 is similar to that of the SGSN 106 in UMTS system (general packet radio service (hereafter referred to as GPRS) supporting node). And it is possible that both MME and Serving Gateway could be located in the same physical entity. The packet data network (PDN) Gateway 105 is responsible for the functions of charging, legally monitoring, etc. And it is possible that both the Serving Gateway and the PDN Gateway could be located in the same physical entity. SGSN 106 offers routing for data transmission in the existing UMTS. The existing SGSN finds a corresponding Gateway GPRS Supporting Nodes (GGSN) according to Access Point Name (APN). HSS 107 is the UE's home subscriber sub-system, which is responsible for storing user's information such as the UE's current location, the serving node's address, user's security related information, UE's activated packet data protocol (PDP) context and so on. PCRF 108 (Policy control and Charging Function) provides QoS policy and charging rules through an interface S7.

In general, the user data stream reaches the Serving Gateway 104 through PDN Gateway 105. Then, through the GPRS tunnel protocol (GTP) channel, data is sent by the Serving Gateway to the ENB where said UE is located at, and then it is sent by the ENB to corresponding UE.

The evolved core network EPC consists of MME and S-GW. Here, each eNB in the SAE is connected to several MMEs in the MME pool. And each eNB is connected to several S-GWs in the S-GW Pool. The interface between eNBs is called as an X2 interface, which is responsible for the mobility management when a UE swithess between two ENBs.

The HNB is a Node B used at home and also can be applied in universities and companies, etc. HNB is Plug-and-Play. HNB accesses MME through the interface S1. The difference between an HNB and a general macro node B lies in that: usually not all the UEs can access an HNB. For instance, only the UEs in a user's home or the ones that are allowed to access the HNB can access the corresponding HNB. And for the HNB in a company, only the company's staff and allowed partners can access said HNB. The HNB group (e.g., the HNB in a company) bearing the same access subscriber cluster is called as a CSG (closed subscriber group).

When a UE enters a new tracking area, ENB selects an MME from the MME pool for this UE as the mobility management control entity. The MME connected to the HNB is configured by the operation and maintenance entity and different MMEs may possibly be configured for the HNB each time the HNB is powered on. When a UE switches between the macro Node B and the HNB, it is necessary for the original service MME to locate the MME to which the corresponding HNB is connected, and to make the latter one be the UE's service MME. In the macro Node B, the original service MME can locate the default MME in the corresponding MME pool in virtue of the regional area indicator (RAI), which as well as the MME pool is deployed when the network is deployed. But in the evolved HNB, the MME to which the HNB is connected every time is different and is configured dynamically.

As mentioned above, since the MME to which the HNB is connected is different in each configuration, so at present, it is necessary to inform all MMEs sharing the same area with the HNB every time the MME to which the HNB is connected is changed. If there is any overlap area, it also is necessary to inform the MMEs in the overlap area. Because of the greater number of HNBs, the work load for such notification is large. The present invention provides a method to reduce the workload for the Operation Maintenance.

The subject of the present invention is to provide a method for supporting UE's switching between macro Node B and home Node B (HNB) cell so as to make any other MMEs may be located in the right MME to which the HNB is connected.

For the above purpose, a method for supporting UE's switching between macro Node B and HNB cell comprises the following steps:

1) the HNB sends a configuration parameter request message to an operation control node;

2)the Operation control node sends a configuration parameter response message to the HNB, in which message comprises the information of a Mobility Manage Entity MME to which the HNB is connected;

3) a UE obtains the information of MME to which the HNB is connected through the HNB broadcasted information;

4) the UE sends a measuring report message to the macro Node B, and in such message it comprises the information of the MME to which the HNB is connected.

The present invention is possible to make any other MMEs may be located in the right MME to which the HNB is connected.

Figure 1 shows the network structure view of SAE;

Figure 2 shows the embodiment 1 of the present invention;

Figure 3 shows the embodiment 2 of the present invention.

The embodiment 1 of the present invention is illustrated in Figure 2. The following is the detailed description to this figure. And the detailed technical description that has nothing to do with the present invention is omitted in the following.

Step 201: The HNB needs to obtain some configuration parameters from the operation and maintenance entity. When the HNB is powered on for the first time, it is necessary for itself to obtain some configuration parameters. The HNB can store these configuration parameters, or the HNB does not store such information and it obtains these parameters from the operation and maintenance entity every time it is powered on. And in the latter situation, each time the HNB is powered on, it can flexibly change these configuration parameters. In another way, when it is necessary, the HNB obtains the configuration parameters from the operation and maintenance entity. The HNB sends a configuration parameter request message to an operation control node, and in such message it contains the HNB's address information.

Step 202: An operation control entity sends a configuration parameter response message to the HNB. In such message it contains the IP address of the MME to which the HNB is connected, the frequencies information that the HNB uses, the HNB's TA identifier, the HNB's user group identifier and the HNB's identifier. According to the first solution, the HNB's identifier contains the information of the MME to which the HNB is connected. And according this information on the MME, other network entities can locate the right MME to which the HNB is connected. The composition of the HNB's identifier is shown as follows:

MCC + MNC + MME Group Id + MME code + Identity

or

MCC + MNC + TAC + MME code + Identity

MCC stands for the country code. MNC stands for the mobile network code. MME Group Id or TAC identifies a group of MMEs, such as a MME pool. MME code uniquely identifies one MME in said group. Identity is used to uniquely identify an ENB in a MME.

If it is not expected to modify the composition of the Node B's identifier, the second solution can be utilized here, i.e., to broadcast the service MME information like the MME group identifier and the MME code in virtue of the home cell's broadcast information, or to broadcast TAC, MME code in virtue of the home cell's broadcast information.

Step 203: The HNB broadcasts the home cell's information in virtue of the broadcast information, such as the home cell's indicator, the HNB cell's TA identifier, the user group identifier and the HNB's identifier. If the first solution described in step 202 is utilized here, the HNB's identifier contains the information on MME to which the HNB is connected. If the second solution described in step 203 is utilized here, the HNB's broadcast information contains such information on the service MME as the MME code.

Step 204: UE stays in connection mode in the macro cell. Said macro cell is adjacent to the home cell. For a user in the macro cell, the UE's context is stored in a certain MME in the MME pool. Said MME is the user's service MME. The following approach can be adopted to choose the service MME: if the user is in connection mode and enters the area of the MME pool, the source Node B sends a switching request message to the source MME, in which message it includes the destination Node B's address. According to the destination Node B's address and the information stored in MME, the source MME finds the corresponding MME pool. Each MME pool has an MME with default configuration. And this default MME is just the one that the source MME is searching for. Another MME sharing the same MME pool with the default MME can be specified as the UE's service MME, or just the default one is specified as the UE's service MME. When the UE stays in idle mode and enters the area of the MME pool, it sends an area update message to the macro cell. And the macro cell chooses a service MME for UE according to the load balancing rule.

UE sends a measuring report to the macro cell. In such report it contains the information of the HNB. For the HNB, it is necessary for a UE to monitor the home cell's broadcast channel to obtain such parameters as the home cell's TA identifier, the user group identifier and the HNB's identifier. The UE sends said information to the macro cell in virtue of the measuring report. The macro Node B decides to switch the user to the HNB according to the measuring report and the resource management information. The Detailed switching steps are illustrated in figure 3.

Step 301: The UE sends a measuring report message to the macro Node B.

Step 302: The macro Node B decides to switch the user to the HNB according to the measuring report and the resource management information. The Macro Node B sends a switching request message to the source MME, viz., the MME corresponding to the macro Node B's UE. And in such information it includes the source and destination information, the container from source cell to the destination cell, and the UE identifier applied in the interface S1. The source and destination information refers to the source Node B's identifier and the destination Node B's identifier. For a specific cell, its identifier is contained in said container. The container is sent to the destination node B through a MME transparent transmission mode and also contains user C-RNTI and access layer information, the information on SAE Bearer (e.g., SAE Bearer identifier), such as data connection identifier, QoS information and so on. If the destination Node B is a home cell which owns only one cell in a home Node B, then the container can contain no cell identifier. There are two user identifiers used for the S1 interface, i.e., an MME UE S1AP identifier that is allocated to the user by the service MME and an eNB UE S1AP identifier that is allocated to the user by source node B. In the second solution based on step 202, optionally, the message may contain the HNB's service MME information, such as the MME Group identifier and the MME code.

Step 303: the source MME analyzes the destination Node B's identifier. If the destination Node B is an HNB, the source MME can obtain the HNB's service MME information according to the HNB's identifier. Then the MME can be located to which the corresponding HNB is connected. Since the HNB's identifier contains the MME's group information and the unique MME code in this group, the MME firstly finds the corresponding group and then finds the corresponding MME according to said information. Therefore, whether the MME to which the HNB is connected shares the same MME pool with the source MME, the MME can always find the corresponding service MME for the HNB. The source service MME sends a forward reset request message to the MME to which the HNB is connected. Or, in the second solution based on step 202, the switching request message contains such information elements as the information on the MME to which the HNB is connected, which is adopted to find he address of the MME to which the HNB is connected according to the information on the MME to which the HNB is connected.

Step 304: The destination MME finds corresponding HNB according to the information on the destination Node B and sends a switching request message to the HNB. The switch request includes the QoS information which is connected by the accessed SAE data, and the RRC container information. The RRC container contains the radio control information for the destination cell which is transferred to the destination cell in an MME transparent mode. The message also includes a user MME UE S1AP identifier used for the S1 interface, which is allocated to the user by the MME.

Step 305: the HNB judges whether this user can be accessed according to the QoS information which is connected by the SAE data. If the HNB can provide required resource, it configures the required resource, allocates a user identifiers C-RNTI used for an air interface and an eNB UE S1AP identifier used for the interface S1. Then it sends a switching request response message to the home cell's service MME, and in such message it contains the above information. The message also includes a switching command message which shall be sent to the UE and transmitted to source cell through the container from destination cell to source cell via an MME transparent transmission mode. In the container a new C-RNTI and access stratum information and so on are contained.

Step 306: the destination MME sends a forward reset response message to the source MME. The message includes the container in Step 305.

Step 307: the source MME sends a switching command to the source macro cell. The message contains information on the successfully established SAE data connection and identifier of the SAE data connection to be released, and the identifier allocated by the destination cell to UE for the interface S1, and the identifier allocated by the destination MME to UE for the interface S1. Moreover, it also includes the container in Step 305.

Step 308: the source macro Node B sends a switching command to the UE.

Step 309: when UE carries out synchronization process in the destination cell successfully, it will send a switching completed message to the destination home cell.

Step 310: the HNB sends a switching notification message to the MME to which the HNB is connected, and in such message it contains the user identifier for the interface S1.

Step 311: the destination MME sends a forward reset completed message to the source MME.

Step 312: the source MME sends a response to the forward reset completed message to the destination MME. The Reset process is completed. After the reset process is completed, it also includes area update process initiated by the UE. During the area update process, the UE information at the source MME terminal is released and the MME information contained in the HSS is updated. The current process can be utilized so that its description is omitted in this invention.

Although the invention is described as said embodiments, what is necessary to be pointed out is that all these embodiments are used to explain, rather than restrict the present invention. Those skilled in the art could easily modify, add, delete any step in these embodiments, without deviating from the spirit and scope of the present invention.

Claims

A method for supporting UE's switching between a macro Node B and a home Node B cell, comprising the following steps:

1) sending, by a HNB a configuration parameter request message to an operation control node;

2) sending, by an Operation control node a configuration parameter response message to the HNB, and in such message it comprising the information on a mobility manage entity MME to which the HNB is connected;

3) obtaining, by UE the information on MME to which the HNB is connected from the HNB's broadcast message;

4) sending, by UE a measuring report message to the macro Node B, and in said message it comprises information on the MME to which the HNB is connected.
The method according to Claim 1, further comprising:

switching, by the macro Node B the UE to the HNB by utilizing the received information.
The method according to Claim 1, wherein the configuration parameter request message comprises the address of the HNB.
The method according to Claim 1, wherein the broadcast message comprises the home cell's identifier, the home cell's TA identifier, the user group identifier and the HNB's identifier.
The method according to Claim 4, wherein the HNB's identifier comprises the information on the MME to which the home Node B is connected.
The method according to Claim 1, wherein the broadcast message comprises the information on the MME to which the HNB is connected.
The method according to Claim 1, wherein the configuration parameter response message comprises the HNB's identifier.
The method according to Claim 2, wherein the process in which the macro Node B switches UE from the macro Node B to the HNB in virtue of the received information comprising the following steps:

deciding, by an ENB to switch UE to the HNB and sending the switch request message to a source MME;

finding, by the source MME the MME to which the corresponding HNB is connected and the source service MME sending the switch request message to the MME to which the HNB is connected according to the HNB's identifier;

sending, by aHNB's service MME the switch request message to HNB;

sending, by the HNB a reply message for the switch request to the MME to which the HNB is connected;

sending, by the MME to which the HNB is connected a switching response message to the source MME;

sending, by the Source MME a switching command message to the source ENB;

sending, by the ENB a switching command message to the UE;

sending, by the UE a switching completed message to the HNB; and

sending, by the HNB a switching notification message to the MME to which the HNB is connected.
The method according to Claim 8, wherein the switching request message comprises the source Node B's identifier and destination's ID.
The method according to Claim 8, wherein the switch request message comprises QoS information and RRC container information which is connected by the accessed SAS data.