Abstract:
The method for establishing a connection by a HNB comprising operations of: the HNB transmitting an “attachment request” message to an operation and maintenance center (OMC); the OMC transmitting an “attachment response” message to the MB; the HNB establishing a connection with an MME indicated by the “attachment response” message. With the method proposed, a UE can switch between HNBs in the same CSG through interface X2. Meanwhile, such information as the radio resource management and so on can be exchanged between two HNBs.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This is a continuation application of a prior U.S. patent application assigned Ser. No. 12/673,223, filed Feb. 12, 2010, which issued as U.S. Pat. No. 9,271,165 on Feb. 23, 2016, and which is U.S. National Stage application under 35 U.S.C. §371 of an International application filed on Sep. 16, 2008, and assigned application No. PCT/KR2008/005445, which claims the benefit of a Chinese patent application filed on Sep. 29, 2007, in the Chinese Intellectual Property Office and assigned Serial number 200710164106.5, the entire disclosures of each which are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure generally relates to communication technology, especially to a method for accessing a network by an HNB (home Node B). 
       BACKGROUND 
       [0003]    A system structure of SAE according to the related art is illustrated in  FIG. 1 . The system structure of system architecture evolution (SAE) in  FIG. 1  is described as following. 
         [0004]    User Equipment  101  (hereinafter referred to as UE) is a terminal device used to receive data.  102  EUTRAN, also called ENB, is a radio access network of the LTE SAE, for providing interface through which an LTE mobile station accesses the radio network. Through interface S1, EUTRAN connects to a mobility management entity (MME)  103  and a user plane entity serving gateway (S-GW)  104  in the mobile station. MME  103  is adapted for managing mobile context, session context for the UE, and holding user information on security. S-GW  104  primarily provides a function of user plane. An interface S1-MME is adapted for establishing radio access bearer, forwarding messages from UE to MME through a wireless access network. The combination of MME  103  and S-GW  104  is similar to the original serving general packet radio service (GPRS) support node (SGSN)  106 . It is possible that both MME and S-GW locate at the same physical entity. Packet data network (PDN) Gateway  105  is adapted for the functions like accounting, legally monitoring, etc. And it is possible that both the S-GW and the PDN Gateway locate at the same physical entity. SGSN  106  provides routing for data transmission in existing universal mobile telecommunications system (UMTS). An existing SGSN finds a corresponding gateway GPRS supporting node (GGSN) according to an access point name (APN). HSS  107  is a home subscription sub-system for the UE and is adapted for storing user information such as the current location of UE, address of the serving node, security information on the user, activated packet data protocol (PDP) context for the UE and so on. Policy and charging rules function (PCRF)  108  provides quality of service (QoS) policy and accounting rules through interface S7. 
         [0005]    In general, a user data stream reaches the S-GW  104  through PDN Gateway  105 . Then, through the GPRS tunnel protocol (GTP) channel, data is sent by the S-GW to the ENB where the UE locates in, and now it is sent by the ENB to corresponding UE. 
         [0006]    HNB refers to a Node B applied in a home. It also can be applied in such site as a university, a company and so on. HNB is a plug and play device. Difference between an HNB and a general macro node B is that: in general not all user equipments (UEs) can access an HNB. For example, only the UEs in a user&#39;s home or that are allowed to access the HNB can access the corresponding HNB. And for the HNB in a company, only the company&#39;s staff and its allowed partners can access the HNB. The HNB group (e.g., the HNB in a company) bearing the same access subscriber cluster is called closed subscriber group (CSG). No interface X2 (interface between Node Bs in SAE) exists between general HNBs (e.g., the HNBs in homes) or between an HNB and a macro Node B. Through interface S1, a UE switches between HNBs or between an HNB and a macro Node B. 
         [0007]    For an HNB applied in a company or university or the like, a UE frequently moves between two HNBs in the same company. In this case, the switch is always implemented through interface S1 so that great delay causes and efficiency is very poor. In addition, information such as radio resource management and so on cannot be exchanged between two HNBs in the same company so that resources cannot be utilized effectively. 
         [0008]    The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure. 
       SUMMARY 
       [0009]    Aspects of the present disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to provide a method for establishing a connection by a Home Node B HNB. 
         [0010]    To achieve the object mentioned above, a method for establishing a connection by a HNB comprising operations of: the HNB transmitting an “attachment request” message to an operation and maintenance center (OMC); the OMC transmitting an “attachment response” message to the HNB; the HNB establishing a connection with an MME indicated by the “attachment response” message; 
         [0011]    With the method proposed in the present disclosure, a UE can switch between HNBs in the same CSG through interface X2. Meanwhile, such information as the radio resource management and so on can be exchanged between two HNBs. 
         [0012]    Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0014]      FIG. 1  shows a network structure of SAE acording to the related art; 
           [0015]      FIG. 2  shows a process that a connection is established for HNB in embodiment 1 of the present disclosure; 
           [0016]      FIG. 3  shows the process that a connection is established for HNB in embodiment 2 of the present disclosure; 
           [0017]      FIG. 4  shows an operation flows at HNB according to embodiment 1 and embodiment 2 respectively; 
           [0018]      FIG. 5  shows an operation flows at OMC according to embodiment 1 and embodiment 2 respectively; 
           [0019]      FIG. 6  shows an operation flows at MME according to embodiment 1 and embodiment 2 respectively; and 
           [0020]      FIG. 7  shows a process of reconfiguring MME or S-GW. 
       
    
    
       [0021]    Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
       DETAILED DESCRIPTION 
       [0022]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
         [0023]    The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents. 
         [0024]    It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces 
         [0025]    An embodiment 1 of the present disclosure is illustrated in  FIG. 2 . Following is a detailed description with reference to  FIG. 2 . Detailed technical description for the known components is omitted. In this embodiment, within a CSG, HNB 1  is a first HNB that accesses the network. 
         [0026]    In operation  201 , HNB 1  transmits an “attachment request” message to the OMC. This message contains information on a location of the HNB. Optionally, the “attachment request” message contains an identifier of the CSG to which the HNB belongs. Optionally, the network assigns the CSG identifier to HNB (the first HNB or the first group of HNBs within the CSG) when HNB signs in, or knows the identifier of the CSG to which the HNB (not the first signed in group of HNBs in the CSG) belongs when HNB signs in. 
         [0027]    In operation  202 , OMC selects an MME for the HNB. Within the CSG, the HNB is the first one that accesses the network. OMC selects an MME for it among the MMEs adjacent to the HNB according to a certain rule such as for balancing the load, reducing a possibility of changing MME when UE moves, and so on. Optionally, OMC may select an S-GW for the HNB according to the same rule as on the selection of MME. HNB and OMC check other HNBs in the CSG which need to establish X2 connection with the HNB. According to the CSG identifier, OMC checks other HNBs in the CSG which need to establish X2 connection with the HNB. Optionally, the addresses of the HNBs are considered when OMC checks other HNBs in the CSG which need to establish X2 connection with the HNB. For example, it is not necessary to establish interface X2 between two HNBs if the two HNBs that are in different countries but in the same company belong to the same CSG. In this embodiment, no other HNB exists in the CSG. 
         [0028]    The process of selecting S-GW for HNB can be implemented by the MME connected to the HNB when data is transferred through the HNB. Therefore, the HNBs in the same CSG connect to the same S-GW. If it is necessary for the first HNB in the CSG to establish the user plane, MME selects an S-GW for the CSG according to such rules as to balance load or to reduce the possibility of changing S-GW when a UE moves, and so on. 
         [0029]    In operation  203 , OMC transmits an “attachment response” message to the HNB. This message indicates the MME selected by the OMC for the HNB. Optionally, this message indicates other HNBs necessary to establish X2 connection and adjacent to the HNB. Optionally, the message contains the frequency for using the HNB. The “attachment response” message contains the information on adjacent cells. The “attachment response” message contains a track area identifier (TAI) for the HNB. The “attachment response” message contains the identifier assigned to the HNB. Optionally, the message contains an address of the S-GW that OMC selected for the HNB. 
         [0030]    In operation  204 , HNB initiates a process to establish a connection with the MME indicated by the message. HNB transmits a “connection request” message to MME. The message contains the information on “cells which are overlapped with HNB or CSG”. Optionally, the message contains an information element of the identifier of the TAI where HNB locates in. Optionally, the message contains the information element of the identifier of HNB. Optionally, the message contains the information element of the identifier of the CSG where HNB locates. MME transmits a “connection response” message to HNB. 
         [0031]    Embodiment 2 of the present disclosure is illustrated in  FIG. 3 . Following is detailed description to the  FIG. 3 . Detailed technical description for known components is omitted. In this embodiment, HNB 1  and HNB 2  belong to the same CSG. HNB 1  has accessed the network. And HNB 2  begins to accessing the network for a first time. 
         [0032]    In operation  301 , HNB 2  transmits the “attachment request” message to the OMC. This message contains the information on the location of HNB 2 . Optionally, the “attachment request” message contains the identifier of the CSG to which the HNB 2  belongs. Optionally, the network knows the identifier of the CSG to which the HNB belongs when HNB signs in. 
         [0033]    In operation  302 , OMC selects an MME for the HNB. If the HNB is not the first to access the network in the CSG, the MME selected by OMC for other HNBs in this CSG is just the one that the HNB should connect to. In this embodiment, OMC assigns both the MME and the S-GW selected for HNB 1  to the HNB. Optionally, the address the HNB should be considered when OMC selects MME for the HNB. For example, if two HNBs that are in different countries but in the same company belong to the same CSG, they may not be able to connect to the same MME. In this case, if no adjacent HNB accesses the network, OMC thinks that this HNB is the first one which accesses the network in the CSG and selects an MME for it according to rules such as balancing load or reducing possibility of changing MME when a UE moves, and so on. Optionally, selection of S-GW for the HNB can be implemented by OMC according to the same rules on the selection of MME. OMC checks other HNBs in the CSG which need to establish X2 connection with the HNB. And according to the CSG identifier, OMC checks other HNBs in the CSG which need to establish X2 connection with the HNB. Optionally, the addresses of the HNBs, as well as whether the HNBs share the same CSG or not, are considered when OMC checks other HNBs in the CSG which need to establish X2 connection with the HNB. For example, it is not necessary to establish interface X2 between two HNBs if the two HNBs that are in different countries but in the same company belong to the same CSG. In this embodiment, for example, it is necessary to establish X2 connection between HNB 1  and HNB 2 . 
         [0034]    The process of selecting S-GW for HNB can be implemented by the MME connected to the HNB when data is transferred through the HNB. Therefore, the HNBs in the same CSG connect to the same S-GW. If it is necessary for the first HNB in the CSG to establish the user plane, MME selects an S-GW for the CSG according to such rules as to balance load or to reduce the possibility of changing S-GW when a UE moves, and so on. If the HNB is not the first necessary to establish a user plane in the CSG, the S-GW selected by MME for other HNBS in this CSG is just the one that the HNB should connect to. 
         [0035]    In operation  303 , OMC transmits the “attachment response” message to the HNB 2 . This message indicates the MME that the OMC selected for the HNB. And the MME information included in the message may be the IP address of the MME. Optionally, this message contains a list of other HNBs necessary to establish X2 and adjacent to the HNB. The HNB list information included in the message is an IP address list for the HNB. Optionally, the message contains a frequency for using the HNB. The “attachment response” message contains the information on adjacent cells. The “attachment response” message contains the track area identifier (TAI) for the HNB. The “attachment response” message contains the identifier assigned to the HNB. Optionally, the message contains the address of the S-GW that OMC selected for the HNB. 
         [0036]    In operation  304 , HNB 2  initiates a process to establish a connection with the HNB indicated by the message. HNB 2  transmits the “connection request” message to the other HNB (e.g., HNB 1 ). HNB 1  transmits the “connection response” message to HNB 2 . 
         [0037]    In operation  305 , HNB 2  initiates a process to establish a connection with the MME indicated by the message. HNB 2  transmits the “connection request” message to MME. The message contains the information on “cells which are overlapped with the HNB or CSG”. The message contains the information element of the identifier of the TAI where HNB locates. Optionally, the message contains the information element of the identifier of HNB. Optionally, the message contains the information element of the identifier of the CSG where HNB locates. MME transmits the “connection response” message to HNB 2 . 
         [0038]    The sequence of performing operation  304  and operation  305  is not limited. 
         [0039]    In this embodiment, the operation flow of HNB is illustrated in  FIG. 4 . Here, detailed technical description for known components is omitted. 
         [0040]    In  401 , HNB transmits the “attachment request” message to the OMC. This message contains the information on the location of HNB. Optionally, the “attachment request” message contains the identifier of the CSG to which the HNB 2  belongs. In  402 , HNB waits for the response message. In  403 , if HNB receives a “successful attachment response” message, it saves the information that is included in the message, such as information on MME and the information on other HNBs, TAI, the HNB identifier and so on. In  404 , HNB initiates the process to establish a connection with the MME indicated by the message. HNB transmits the “connection request” message to MME. Optionally, the message contains the information on “cells which are overlapped with the HNB or CSG”. Optionally, the message contains the information element of the identifier of the TAI where HNB locates. Optionally, the message contains the information element of the identifier of HNB. Optionally, the message contains the information element of the identifier of the CSG where HNB locates. MME transmits the “connection response” message to HNB.  405  Optionally, if the “attachment response” message contains information on other HNBs, such as HNB IP address list, HNB initiates the process to establish connections with other HNBs. HNB transmits the “connection request” to another HNB. Another HNB transmits the “connection response” message to the HNB. 
         [0041]    The sequence of performing operation  404  and operation  405  is not limited. 
         [0042]    In this embodiment, the operation flow of OMC is illustrated in  FIG. 5 . Here, detailed technical description for known components is omitted. 
         [0043]    In  501 , OMC receives messages. In  502 , if OMC receives the “attachment request” message from HNB, in  503  it saves HNB related information. And if the message contains the location information for HNB, OMC saves this information. And if the message contains the identifier of the CSG where the HNB belongs, OMC saves this information. 
         [0044]    In  504 , if the HNB is the first to access the network in corresponding CSG, in  505 , OMC selects an MME for HNB in this CSG. OMC selects the MME according to either the address of HNB, or the rule to balance load or to reduce the possibility of changing MME when a UE moves, etc. Optionally, OMC can select an S-GW for the HNB according to the same rule as on the selection of MME. 
         [0045]    In operation  506 , if HNB is not the first to access the network in the CSG,  507  OMC checks other HNBs in the CSG.  508  OMC transmits the “attachment response” message to the requesting HNB. And information on the MME OMC selected for HNB in this CSG is included in the message. Optionally, the “attachment response” message contains the information on the S-GW selected by OMC for HNB in this CSG. Optionally, the message contains the information on other HNBs in this CSG, such as the IP address list for the HNB. Optionally, the message contains the identifier of the TAI where the HNB locates. Optionally, the message contains the HNB identifier allocated to the HNB. The case described above is for that the HNBs in the CSG are not far away from one another. In another case, for example, two HNBs belong to the same CSG in different countries but in the same company, if no adjacent HNB accesses the network, OMC thinks that this HNB is the first one which accesses the network in the CSG and selects an MME for it according to such rules as to balance load or to reduce possibility of changing MME when a UE moves, and so on. Optionally, OMC can select an S-GW for the HNB according to the same rule as on the selection of MME. In this case, OMC finds the other HNB is the one necessary to establish a X2 connection with the HNB in the CSG according to not only the CSG ID. Meanwhile, it should consider the location of the HNB. For example, it is not necessary to establish interface X2 between two HNBs if the two HNBs that are in different countries but in the same company belong to the same CSG. 
         [0046]    In this embodiment, the operation flow of MME is illustrated in  FIG. 6 . Here, detailed technical description for the known components is omitted. 
         [0047]    In  601  MME receives messages. In  602  if MME receives the “connection request” message from HNB, in  603  MME saves the information which is included in this message, such as the information on “cells which is overlapped with the HNB or CSG”, the identifier of the TAI where HNB locates, the HNB identifier.  604  MME transmits the “connection response” message to HNB. 
         [0048]      FIG. 7  illustrates the process that OMC reconfigures CSG&#39;s MME or S-GW when overload or fault comes across the MME or the S-GW. 
         [0049]    In operation  701 , OMC finds that overload or fault comes across the MME or S-GW connected to a certain CSG. 
         [0050]    In operation  702 , OMC transmits a “reconfiguration request” message to the HNB in CSG. In this message, the information on the reconfigured MME or S-GW and the reason for the reconfiguration are included. And the reconfiguration can be done to the IP address of the MME or the S-GW. 
         [0051]    In operation  703 , the HNB that has received the “reconfiguration request” message transmits the “connection request” message to the new MME or S-GW. Optionally, the “connection request” message sent to MME includes the information on “cells which are overlapped with the HNB or CSG”. Optionally, the “connection request” message sent to MME contains the information element of the identifier of the TAI where HNB locates. The new MME or S-GW transmits the “connection response” message to the HNB. 
         [0052]    In operation  704 , the HNB transmits a “reconfiguration response” message to OMC. 
         [0053]    Optionally, if the reconfiguration results from the overload of MME or S-GW, HNB initiates the process of releasing the connection with original MME or S-GW. 
         [0054]    While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.