Abstract:
The present disclosure relates to a communication method and system for converging a 5 th -Generation (5G) communication system for supporting higher data rates beyond a 4 th -Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. To provide multiple connections, a method of operating a terminal includes receiving a message instructing to establish a second connection based on a second radio access technology (RAT) from a first access node which provides a first connection based on a first RAT, and transmitting a signal for establishing the connection to a second access node using the second RAT.

Description:
RELATED APPLICATION(S) 
       [0001]    The present application claims the benefit under 35 U.S.C. §119(a) to a Korean patent application filed in the Korean Intellectual Property Office on Oct. 7, 2014, and assigned Serial No. 10-2014-0134997, the entire disclosure of which is hereby incorporated by reference. 
       BACKGROUND 
       [0002]    The present disclosure relates generally to multiple connections in a wireless communication system. 
         [0003]    To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed. 
         [0004]    The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology” have been demanded for IoT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications. 
         [0005]    In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the 5G technology and the IoT technology. 
         [0006]    A wireless communication system makes great progress in hardware and software so as to provide a better communication quality. For example, a communication technique using a plurality of antennas, rather than a single antenna, is developed, and a technique for restoring a physical signal to data more efficiently is under development. 
         [0007]    To satisfy growing demands for high capacity communication, multiple connections are provided. For example, Carrier Aggregation (CA) of a Long Term Evolution (LTE) system can provide multiple connections using a plurality of carriers. Hence, a user can be serviced using more resources. 
       SUMMARY 
       [0008]    To address the above-discussed deficiencies of the prior art, it is a primary aspect of the present disclosure to provide an apparatus and a method for providing multiple connections in a wireless communication system. 
         [0009]    Another aspect of the present disclosure is to provide an apparatus and a method for providing multiple connections using different radio access technologies (RATs) in a wireless communication system. 
         [0010]    Yet another aspect of the present disclosure is to provide an apparatus and a method for selecting an access node for multiple connections in a wireless communication system. 
         [0011]    Still another aspect of the present disclosure is to provide an apparatus and a method for restricting access to an access node for multiple connections in a wireless communication system. 
         [0012]    A further aspect of the present disclosure is to provide an apparatus and a method for controlling a status of an access node for multiple connections in a wireless communication system. 
         [0013]    A further aspect of the present disclosure is to provide an apparatus and a method for determining whether to provide multiple connections in a wireless communication system. 
         [0014]    A further aspect of the present disclosure is to provide an apparatus and a method for determining whether to terminate multiple connections in a wireless communication system. 
         [0015]    According to one aspect of the present disclosure, a method of operating a terminal in a wireless communication system includes receiving a message instructing to establish a second connection based on a second RAT from a first access node which provides a first connection based on a first RAT; and transmitting a signal for establishing the connection to a second access node using the second RAT. 
         [0016]    According to another aspect of the present disclosure, a method of operating a first access node using a first RAT in a wireless communication system includes transmitting a message instructing to establish a second connection based on a second RAT, to a terminal; and transmitting a part of data destined for the terminal through a first connection based on the first RAT and remaining data to the terminal via a second access node which provides the second connection. 
         [0017]    According to yet another aspect of the present disclosure, a method of operating a second access node using a second RAT in a wireless communication system includes receiving a signal for establishing a connection from a terminal; and transmitting data between a first access node using a first RAT and the terminal, to the terminal using the second RAT. 
         [0018]    According to still another aspect of the present disclosure, an apparatus of a terminal in a wireless communication system includes a receiver for receiving a message instructing to establish a second connection based on a second RAT from a first access node which provides a first connection based on a first RAT; and a transmitter for transmitting a signal for establishing the connection to a second access node using the second RAT. 
         [0019]    According to a further aspect of the present disclosure, an apparatus of a first access node using a first RAT in a wireless communication system includes a wireless communication unit for transmitting a message instructing to establish a second connection based on a second RAT, to a terminal; and a controller for controlling to transmit a part of data destined for the terminal through a first connection based on the first RAT and remaining data via a second access node which provides the second connection. 
         [0020]    According to a further aspect of the present disclosure, an apparatus of a second access node using a second RAT in a wireless communication system includes a receiver for receiving a message for establishing a connection from a terminal; and a transmitter for transmitting data between a first access node using a first RAT and the terminal, to the terminal using the second RAT. 
         [0021]    Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The above and other aspects, features, and advantages of certain exemplary embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0023]      FIG. 1  illustrates a network of a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0024]      FIG. 2  illustrates a method for establishing a connection with an access node providing an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0025]      FIG. 3  illustrates a method for establishing a connection with an access node providing an additional connection in a wireless communication system according to another exemplary embodiment of the present disclosure; 
           [0026]      FIG. 4  illustrates a method for restricting access to an access node providing an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0027]      FIG. 5  illustrates a method for restricting access to an access node providing an additional connection in a wireless communication system according to another exemplary embodiment of the present disclosure; 
           [0028]      FIG. 6  illustrates a method for controlling a status of an access node for multiple connections in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0029]      FIG. 7  illustrates a method for instructing to establish an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0030]      FIG. 8  illustrates a method for instructing to release an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0031]      FIG. 9  illustrates a method for controlling multiple connections in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0032]      FIG. 10  illustrates a packet delivered through an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0033]      FIG. 11  illustrates operations of a terminal in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0034]      FIG. 12  illustrates operations of a first access node in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0035]      FIG. 13  illustrates operations of a second access node in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0036]      FIG. 14  illustrates a terminal in a wireless communication system according to an exemplary embodiment of the present disclosure; 
           [0037]      FIG. 15  illustrates a first access node in a wireless communication system according to an exemplary embodiment of the present disclosure; and 
           [0038]      FIG. 16  illustrates a second access node in a wireless communication system according to an exemplary embodiment of the present disclosure. 
       
    
    
       [0039]    Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
       DETAILED DESCRIPTION 
       [0040]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention 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 embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
         [0041]    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 invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
         [0042]    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. 
         [0043]    By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. 
         [0044]    Exemplary embodiments of the present disclosure provide a technique for providing multiple connections in a wireless communication system. 
         [0045]    Hereinafter, a term for identifying an access node, terms for indicating network entities, terms for indicating messages, a term for indicating an interface between the network entities, and terms for indicating various identification information are used to ease the understanding. Accordingly, the present disclosure is not limited to those terms to be explained and can adopt other terms of technically equivalent meanings. 
         [0046]    To ease the understanding, the present disclosure uses, but not limited to, terms and names defined in 3 rd  Generation Partnership Project (3GPP) Long Term Evolution (LTE) and Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The present disclosure can be equally applied to systems conforming to other standards. 
         [0047]    Now, the present disclosure provides multiple connections using a Wireless Local Area Network (WLAN) technology in a cellular communication system. Notably, the present disclosure can employ other radio access technology (RAT), for example, Bluetooth and Bluetooth Low Energy (BLE) besides the WLAN. 
         [0048]      FIG. 1  depicts a network of a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0049]    Referring to  FIG. 1 , the wireless communication system includes a base station (BS) A  110 - 1 , a BS B  110 - 2 , a BS C  110 - 3 , a Mobility Management Entity (MME)/Serving Gateways (S-GWs)  120 - 1  and  120 - 2 , and an Access Point (AP)  130 . While three BSs are depicted, more or less BSs may be included in the wireless communication system. The MME/S-GWs  120 - 1  and  120 - 2  each can be divided into the MME and the S-GW. 
         [0050]    The BSs  110 - 1 ,  110 - 2 , and  110 - 3  are access nodes of a cellular network and provide radio access to terminals accessing the cellular network. That is, the BSs  110 - 1 ,  110 - 2 , and  110 - 3  support connections between the terminals and a core network (not shown). The core network is a communication network that provides various services to customers who are connected by the access network. For example, the core network may include an Internet protocol (IP) network. The BS A  110 - 1  can provide multiple connections to a terminal using the AP  130 . 
         [0051]    The MME/S-GWs  120 - 1  and  120 - 2  manage terminal mobility. The MME/S-GWs  120 - 1  and  120 - 2  can further manage authentication and bearer of the terminal accessing the cellular network. The MME/S-GWs  120 - 1  and  120 - 2  process a packet received from the BS  110  or a packet to be forwarded to the BSs  110 - 1 ,  110 - 2 , and  110 - 3 . 
         [0052]    The AP  130  is an access node of a WLAN network and provides radio access to the terminals (not shown). In particular, the AP  130  can provide multiple WLAN-based connections to a terminal (not shown) under control of the BS A  110 - 1 . The AP  130  can be included in the BS A  110 - 1  or connected to the BS A  110 - 1  via a separate interface. In this case, the BS A  110 - 1  can transmit a part of downlink data directly to the terminal and the remaining downlink data to the terminal via the AP  130 . The terminal can transmit a part of uplink data directly to the BS  110 - 1  and the remaining uplink data to the AP  130 . 
         [0053]    The terminal can access the cellular network via the BS A  110 - 1 . The BS A  110 - 1  can additionally configure the terminal access to the AP  130  and thus control the terminal to communicate in a wider band. In so doing, even when equipment (e.g., MME, S-GW, Packet data Network Gateway (P-GW)) of the core network does not recognize the multiple connections using the AP  130 , the service can be still provided. 
         [0054]    When the multiple connections are provided via the AP  130 , the connection that delivers the data may be determined. For example, in a downlink, the BS A  110 - 1  can receive data from the core network and determine whether to forward the data over the WLAN or directly to the terminal. In the uplink, the terminal can determine which path to transmit the data to and forward the data to the core network. 
         [0055]      FIG. 2  depicts a method for establishing a connection with an access node providing an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0056]    Referring to  FIG. 2 , in operation  201 , a BS  210  (e.g., BS A  110 - 1  of  FIG. 1 ) transmits AP measurement configuration information to a terminal  200 . The AP measurement configuration information can be carried by a control message of a Radio Resource Control (RRC) layer. For example, the AP measurement configuration information can be carried by an RRCConnectionReconfiguration message. The AP measurement configuration information includes information for leading the terminal  200  to access an AP  230  selected by the BS  210 . For example, the AP measurement configuration information includes necessary information for scanning the AP  230 . More specifically, the AP measurement configuration information can include at least one of an identifier (e.g., Service Set Identification (SSID), Basic Service Set Identification (BSSID)) of the AP  230 , an operating frequency of the AP  230 , and a signal strength threshold for determining scanning success. 
         [0057]    In operation  203 , the terminal  200  performs the scanning. That is, the terminal  200  detects a scanning signal received on a WLAN channel so as to discover the AP  230 . Before doing so, the terminal  200  can transmit a message requesting the scanning signal. For example, the scanning signal can include a beacon signal or a probe signal. When the operating frequency information is received, the terminal  200  can scan only a channel indicated by the operating frequency information, without having to scan all of WLAN channels. Hence, the scanning time and power can be reduced. 
         [0058]    In operation  205 , the terminal  200  transmits a scanning result to the BS  210 . The scanning result can be delivered by a control message of the RRC layer. For example, the scanning result can be delivered by a MeasurementReport message. The scanning result can include the scanning success or failure of the AP  230 , and a signal strength or a signal quality of the AP  230 . When detecting access nodes other than the AP  230 , the terminal  200  can report discovery and measurement information of the other access nodes to the BS  210 . The BS  210  can select one of the detected access nodes including the AP  230  and notify the selected access node to the terminal  200 . In  FIG. 2 , the terminal  200  is assumed to discover the AP  230 . 
         [0059]    In operation  207 , the terminal  200  establishes the WLAN connection. More specifically, the BS  210  transmits to the terminal  200  a message instructing to establish an additional connection via the AP  230 , and the terminal  200  and the AP  230  performing signalings and operations to establish the connection. For example, the terminal  200  can send a message requesting the authentication and a message requesting association to the AP  230 . Hence, the terminal  200  can establish the multiple connections via the AP  230  in addition to the connection of the BS  210 . 
         [0060]      FIG. 3  depicts a method for establishing a connection with an access node providing an additional connection in a wireless communication system according to another exemplary embodiment of the present disclosure. 
         [0061]    Referring to  FIG. 3 , in operation  301 , a terminal  300  transmits signal strength information per remote antenna to a BS  310 . The BS  310  includes a plurality of remote antennas (not shown) distributed over a cell (not shown). The terminal  300  can measure the quality of signals transmitted over the distributed antennas. The signals transmitted over the distributed antennas can be identified based on a signal sequence or a resource location. 
         [0062]    In operation  303 , the BS  310  selects an access node for providing the additional connection to the terminal  300 . The BS  310  knows locations of the remote antennas and controllable WLAN access nodes. Accordingly, the BS  310  can locate the terminal  300  based on the signal strength per remote antenna and determine an access node suitable for the location of the terminal  300 . That is, the BS  310  can select the access node near the remote antenna close to the terminal  300 . In  FIG. 3 , it is assumed that an AP  330  is selected. 
         [0063]    In operation  305 , the terminal  300  establishes the WLAN connection. More specifically, the BS  310  transmits to the terminal  300  a message instructing to establish an additional connection via the AP  330 , and the terminal  300  and the AP  330  perform a signaling and operations to establish the connection. The message can be a control message of the RRC layer. For example, the message can be the RRCConnectionReconfiguration message. For example, the terminal  300  can send a message for requesting the authentication and a message for requesting the association to the AP  330 . Hence, the terminal  300  can establish the multiple connections via the AP  330  in addition to the connection of the BS  310 . 
         [0064]    In this embodiment, the BS  310  selects the AP  330  as the access node for providing the additional connection to the terminal  300 . According to a yet another embodiment, the BS  310  can select a plurality of access nodes. In this case, the BS  310  can finally select one access node based on the scanning result of the terminal  300  on the access nodes. For doing so, the BS  310  can provide the terminal  300  with access node information, and the terminal  300  can scan the access nodes and transmit the scanning result to the BS  310 . 
         [0065]      FIG. 4  depicts a method for restricting access to an access node providing an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0066]    Referring to  FIG. 4 , in operation  401 , a terminal  400  transmits identification information for the terminal  400  to a BS  410 . The identification information can be carried by a control message of the RRC layer. For example, the identification information can be carried by a UECapabilityInformation message. The identification information includes an identifier used in the WLAN access. For example, the identifier can include a Media Access Control (MAC) address of the terminal  400 . 
         [0067]    In operation  403 , the BS  410  forwards the identification information of the terminal  400  to the AP  430 . The BS  410  and the AP  430  can signal with each other using a wired connection between them. The transmitting the identification information can include requesting the AP  430  to permit the access of the terminal of the identification information. 
         [0068]    In operation  405 , the terminal  400  transmits an access request message to the AP  430 . For example, the access request message can include a message for requesting the authentication. Although not depicted in  FIG. 4 , the terminal  400  can scan the AP  430 . 
         [0069]    In operation  407 , the AP  430  determines whether to permit the access. That is, the AP  430  compares the identification information received from the BS  410  with the identification information of the terminal  400  requesting the access. When the identification information received from the BS  410  matches the identification information of the terminal  400  requesting the access, the AP  430  permits the access of the terminal  400 . Next, the WLAN connection may be established. 
         [0070]      FIG. 5  depicts a method for restricting access to an access node providing an additional connection in a wireless communication system according to another exemplary embodiment of the present disclosure. 
         [0071]    Referring to  FIG. 5 , in operation  501 , a BS  510  transmits WLAN access information to a terminal  500 . The WLAN access information can be delivered by a control message of the RRC layer. For example, the WLAN access information can be delivered by the RRCConnectionReconfiguration message. The WLAN access information includes information required to access an AP  530 . For example, the WLAN access information includes at least one of an identification information (e.g., BSSID) and encryption information (e.g., AP encryption key, access password, etc.) of the AP  530 . 
         [0072]    In operation  503 , the terminal  500  accesses the AP  530 . That is, the terminal  500  accesses the AP  530  using the WLAN access information provided from the BS  510 . For example, the terminal  500  can scan the access node of the received identification information and access the scanned access node. For doing so, the terminal  500  can transmit a scanning message including the identification information of the AP  530 . For example, the scanning message can be a probe request message. When access security is set in the AP  530 , the terminal  500  can use the encryption information. 
         [0073]    In  FIG. 5 , only the terminal receiving the access information from the BS  510  can access the AP  530 . Accordingly, the AP  530  does not have to inform terminals of a presence of the AP  530  and thus may not transmit the identification information (e.g., SSID). The AP  530  does not respond to the scanning message which is broadcasted, and responds only to the scanning message which is unicast using the identification information for the AP  530 . That is, the AP  530  can respond only to an active scanning using a directed probe. 
         [0074]      FIG. 6  depicts a method for controlling a status of an access node for multiple connections in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0075]    Referring to  FIG. 6 , in operation  601 , a BS  610  determines whether to activate the WLAN. When there is no need to provide the multiple connections using the WLAN, unnecessary power consumption can be avoided by turning off an AP  630  being the WLAN access node. For example, the BS  610  can determine whether to activate the WLAN based on at least one of the multi-connection supportability of the accessing terminal and a load level. More specifically, when the load level of the BS  610  falls below a threshold, the BS  610  can determine to turn off the AP  630 . In so doing, when a plurality of access nodes is present, the BS  610  can deactivate only some of the access nodes. By contrast, when the load level of the BS  610  exceeds the threshold, the BS  610  can determine to turn on the AP  630 . Alternatively, when there is no terminal supporting the multiple connections, the BS  610  can determine to deactivate the AP  630 . 
         [0076]    In operation  603 , the BS  610  transmits a message instructing to turn on/off to the AP  630 . The BS  610  and the AP  630  can signal with each other using a wired connection between them. When the deactivation is instructed, the AP  630  can deactivate all or some of functions. For example, the AP  630  can deactivate only the scanning signal transmission and maintain the signal reception, that is, continue to monitor the WLAN channel. 
         [0077]      FIG. 7  depicts a method for instructing to establish an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0078]    Referring to  FIG. 7 , in operation  701 , a BS  710  determines whether to add the WLAN connection. That is, the BS  710  determines whether to provide the multiple connections to a terminal  700 . For example, the BS  710  can determine whether to provide the additional connection based on at least one of a class of a bearer allocated to the terminal  700 , a cellular communication quality of the terminal  700 , and WLAN preference information received from the terminal  700 . The class can be obtained from a Quality of Service (QoS) Class Identifier (QCI). The communication quality can be determined based on a Reference Signal Received Power (RSRP), a Reference Signal Received Quality (RSRQ), and a Sounding Reference Signal (SRS) quality. More specifically, when the channel quality falls below a threshold, the BS  710  can determine to provide the multiple connections to the terminal  700 . Alternatively, when a maximum allowable delay of the bearer of the terminal  700  exceeds a threshold, the BS  710  can determine to provide the multiple connections for the corresponding bearer. Alternatively, when a maximum allowable transmission error of the bearer of the terminal  700  exceeds a threshold, the BS  710  can determine to provide the multiple connections for the corresponding bearer. The WLAN preference information can be delivered by a control message (e.g., UECapabilityInformation message) of the RRC layer from the terminal  700  to the BS  710 . The WLAN preference information can indicate whether either or both of the cellular communication and the WLAN communication are preferred. 
         [0079]    In operation  703 , the BS  710  transmits a message instructing to add the WLAN connection to the terminal  700 . The message can be a control message of the RRC layer. For example, the message can be the RRCConnectionReconfiguration message. The message can include WLAN connection identification information (e.g., secondary cell ID), information indicating the bearer to be serviced in the WLAN connection, and necessary information (e.g., identification information, encryption information, operating frequency, beacon interval, etc.) for accessing the AP for the WLAN connection. 
         [0080]      FIG. 8  depicts a method for instructing to release an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0081]    Referring to  FIG. 8 , in operation  801 , a BS  810  determines whether to disconnect the WLAN. That is, the BS  810  determines whether to cease the multiple connections to a terminal  800 . For example, the BS  810  can determine whether to disconnect the WLAN based on at least one of a packet loss rate of the WLAN connection, a modulation and coding scheme (MCS) level of the WLAN connection, a channel quality of the WLAN connection, and a communication quality of the cellular network via the BS  810 . More specifically, when a WLAN Acknowledge (ACK) packet for a downlink packet in the WLAN connection is lost over a threshold, the BS  810  can determine to disconnect the WLAN. An AP for providing the WLAN connection can report the WLAN ACK packet loss of the downlink packet to the BS  810 . Alternatively, when a WLAN ACK packet for an uplink packet in the WLAN connection is lost over a threshold, the BS  810  can determine to disconnect the WLAN. The terminal  800  can report the WLAN ACK packet loss of the uplink packet to the BS  810 . The WLAN ACK packet loss can be carried by a control message (e.g., RadioLinkFailureReport message) of the RRC layer. Alternatively, when the MCS level of the WLAN connection falls below a threshold, the BS  810  can determine to disconnect the WLAN. Alternatively, when the received signal strength of the packet from the terminal  800  to the AP falls below a threshold, the BS  810  can determine to disconnect the WLAN. Alternatively, when the BS  810  resides near the AP and the communication quality of the cellular network falls below a threshold, the BS  810  can determine to disconnect the WLAN. The received signal strength can be determined based on a Received signal Strength Indicator (RSSI), and the communication quality can be determined based on the RSSP, the RSRQ, and the SRS quality. 
         [0082]    In operation  803 , the BS  810  transmits a message instructing to disconnect the WLAN to the terminal  800 . The message can be a control message of the RRC layer. For example, the message can be the RRCConnectionReconfiguration message. The message can include WLAN connection identification information. 
         [0083]      FIG. 9  depicts a method for controlling multiple connections in a wireless communication system according to an exemplary embodiment of the present disclosure. In  FIG. 9  exemplifies an embodiment where the cellular network conforms to the LTE standard. 
         [0084]    Referring to  FIG. 9 , in operation  901 , a terminal  900  transmits capability information to a BS  910 . The capability information can be delivered by a control message of the RRC layer. For example, the capability information can be delivered by a UECapabilityInformation message. The capability information can include information indicating hardware capability and supported functions of the terminal  900 . The capability information can include information indicating whether the multiple connections using different RATs are supported. For example, the capability information can include the MAC address of the WLAN and an accessible channel frequency band. Although not depicted in  FIG. 9 , the BS  910  can transmit the capability information to the MME. Hence, when the terminal  900  accesses again, the BS  910  can receive the capability information of the terminal  900  from the MME, not the terminal  900 . 
         [0085]    In operation  903 , the BS  910  determines whether to turn on/off the AP  930 . That is, if the AP  930  is deactivated, the BS  910  determines whether to activate the AP  930 . For example, the BS  910  can determine whether to activate the AP  930  based on at least one of the multi-connection supportability of the accessing terminals and the load level. More specifically, when the load level of the BS  910  exceeds the threshold, the BS  910  can determine to turn on the AP  930 . 
         [0086]    In operation  905 , the BS  910  instructs the AP  930  to turn on. That is, the BS  910  activates the AP  930 . 
         [0087]    In operation  907 , the AP  930  is turned on. That is, the AP  930  activates the function for providing the additional connection. For example, the AP  930  can apply power to or enable a signal transceiving module. 
         [0088]    In operation  909 , the AP  930  repeatedly transmits a beacon frame. The AP  930  can periodically transmit the beacon frame at certain time intervals. The beacon frame is a signal for notifying the presence of the AP  930 . That is, the beacon frame is used for the terminal  900  to scan the AP  930 . For example, the beacon frame can include a time stamp, a beacon interval, capability information of the AP  930 , and identification information (e.g., SSID, BSSID, Homogeneous Extended Service Set Identifier (HESSID)) of the AP  930 . 
         [0089]    In operation  911 , the BS  910  transmits an RRCConnectionReconfiguration message to the terminal  900 . The RRCConnectionReconfiguration message instructs to add the WLAN connection. For example, the RRCConnectionReconfiguration message can include the WLAN connection identification information (e.g., secondary cell ID), the information indicating the bearer to be serviced in the WLAN connection, and the necessary information (e.g., the identification information, the encryption information, the operating frequency, the beacon interval, etc.) for accessing the AP for the WLAN connection. The RRCConnectionReconfiguration can further include bearer class information to be serviced in the WLAN connection. Although not depicted in  FIG. 9 , before sending the RRCConnectionReconfiguration message, the BS  910  can determine whether to provide the WLAN connection based on at least one of the class of the bearer allocated to the terminal  900  and the cellular communication quality of the terminal  900 . 
         [0090]    In operation  913 , the terminal  900  performs the WLAN authentication/association. The terminal  900  can access the AP  930  using the information received over the RRCConnectionReconfiguration message. In more detail, the terminal  900  can scan the AP  930  and then send a message requesting the authentication and a message requesting the association to the AP  930 . The AP  930  can determine whether to permit the access using the identification information of the terminal  900  received from the BS  910 . The terminal  930  can access the AP  930  using the encryption information received over the RRCConnectionReconfiguration message. 
         [0091]    In operation  915 , the terminal  900  can transmit an RRCConnectionReconfigurationComplete message. That is, the terminal  900  transmits the message notifying the WLAN connected to the AP  930 . 
         [0092]    In operation  917 , the terminal  900  can transmit and receive data to and from the BS  910  over the cellular network and the AP  930  over the WLAN. That is, the terminal  900  transmits and receives data through the connections of the different RATs. That is, the terminal  900  operates in a Carrier Aggregation (CA) mode through the connections of the different RATs. In so doing, the data transmitted and received over the WLAN is a WLAN packet including the packet of the cellular network as a payload. For example, the payload of the WLAN packet can include a packet of a Packet Data Convergence Protocol (PDCP) layer. 
         [0093]    In operation  919 , the BS  910  transmits an RRCConnectionReconfiguration message to the terminal  900 . The RRCConnectionReconfiguration message instructs to disconnect the WLAN. For example, the RRCConnectionReconfiguration message can include the WLAN identification information (e.g., secondary cell ID). Although not depicted in  FIG. 9 , before sending the RRCConnectionReconfiguration message, the BS  910  can determine whether to disconnect the WLAN based on at least one of the packet loss rate of the WLAN connection, the MCS level of the WLAN connection, the channel quality of the WLAN connection, and the communication quality of the cellular network via the BS  910 . 
         [0094]    In operation  921 , the terminal  900  transmits an RRCConnectionReconfigurationComplete message. That is, the terminal  900  transmits the message notifying the WLAN disconnection from the AP  930 . 
         [0095]    In operation  923 , the BS  910  determines whether to turn on/off the AP  930 . That is, if the AP  930  is activated, and the BS  910  determines whether to deactivate the AP  930 . For example, the BS  910  can determine whether to deactivate the AP  930  based on at least one of the multi-connection supportability of the accessing terminals and the load level. More specifically, when the load level of the BS  910  falls below the threshold, the BS  910  can determine to turn off the AP  930 . Alternatively, when there is no terminal supporting the multiple connections, the BS  910  can determine to turn off the AP  930 . 
         [0096]    In operation  925 , the BS  910  instructs the AP  930  to turn off. That is, the BS  910  deactivates the AP  930 . 
         [0097]    In operation  927 , the AP  930  is turned off. That is, the AP  930  deactivates the function for providing the additional connection. For example, the AP  930  can disable or cut the power of all or a part of the signal transceiving module. 
         [0098]    In operation  917  of  FIG. 9 , the terminal  900  can be serviced using both of the cellular connection and the WLAN connection. In so doing, a plurality of terminals including the terminal  900  can use both of the cellular connection and the WLAN connection. In this case, the BS  910  can perform dynamic scheduling based on at least one of a load, a signal strength, a data type, a user calling plan, a user grade (e.g., best client), AP locations, and a crowded time zone. 
         [0099]    Namely, when the BS  910  or the terminal  900  transmits data, the dynamic scheduling determines whether to transmit the data using the cellular connection or the WLAN connection based on current load information, the cellular/WLAN signal strength, or the type or size of the data transmitted/received. 
         [0100]    More specifically, when both of the cellular network and the WLAN are used and the load of the BS  910  is considerable, the data delivered in the WLAN connection can increase. By contrast, when the WLAN load is considerable, the data delivered in the cellular connection can increase. Alternatively, when the load of the AP  930  is considerable, the data delivered in the cellular connection can increase. Alternatively, when the WLAN signal strength is relatively higher, the data delivered in the WLAN connection can increase. Alternatively, when the signal strength of the BS  910  is relatively higher, the data delivered in the cellular connection can increase. 
         [0101]    In addition, the scheduling can determine whether to transmit data through the cellular connection or the WLAN connection, based on the type of the transceived data. The BS  910  or the terminal  900  can determine the type of the transceived data according to the identification information of the data, and transmit the data over the cellular network of a relatively higher data rate when the data type requires a high data rate. By contrast, when the data type requires a low data rate, that is, when a minimum data rate is relatively low, the data can be transmitted over the WLAN of the relatively low data rate. Thus, when various data are simultaneously transmitted, the data can be effectively delivered in consideration of the network characteristics. 
         [0102]    Alternatively, the dynamic scheduling can be conducted based on the user&#39;s calling plan information. For example, when the data size exceeds a certain size, the BS  910  can transmit data above a certain size over the WLAN which does not incur the charge. When a subscriber of the terminal  900  can use the cellular network without incurring an additional charge, the data can be transmitted over the cellular network though the data size exceeds the certain size. 
         [0103]    As above, when neither of the cellular and WLAN signal strengths are good in the dynamic scheduling, subscriber information can be further used. For example, the load can be distributed by prioritizing a network access right based on the time according to an identifier for identifying the best client, such as the subscriber information of the terminal  900 . 
         [0104]    In addition, in the dynamic scheduling, when the BS  910  and the AP  930  are managed by one operator or controlled dynamically, the BS  910  can effectively distribute and transceive (transmit and/or receive) data with respect to the terminals which use both of the cellular connection and the WLAN connection. For example, the operator can locate the AP  930  or detect the crowded time zone, calculate the loads of the cellular connection and the WLAN connection based on the location and the time zone, and then conduct the dynamic scheduling based on the calculation. 
         [0105]      FIG. 10  depicts a packet delivered through an additional connection in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0106]    Referring to  FIG. 10 , a Logical Link Control (LLC)/Subnetwork Access Protocol (SNAP) layer packet  1002  of the WLAN includes a Destination Service Access Point (DSAP) field, a Source Service Access Point (SSAP) field, a control field, an Object Identifier (OID) field, a type field, and an LLC Service Data Unit (LSDU). The LSDU contains a packet of the cellular network as the payload, and the type field is set to a value indicating that the cellular network packet is contained in the LSDU. Herein, the cellular network packet can include a packet of the PDCP layer. Yet, the cellular network packet can include a MAC layer packet, a Radio Link Control (RLC) layer packet, or an RCC layer packet. 
         [0107]    The MAC layer packet  1004  of the WLAN includes a frame control field, a duration/ID field, address fields, a sequence control field, a MAC Service Data Unit (MSDU) including the LLC/SNAP layer packet  1002 , and a Frame Check Sequence (FCS). A Physical (PHY) layer packet  1006  of the WLAN includes a Physical Layer Convergence Procedure (PLCP) preamble, a PLCP header, and a PHY Service Data Unit (PSDU) including the MAC layer packet  1004 . Ultimately, a final packet  1008  includes a WLAN PHY header, a WLAN MAC header, an LLC header, an LTE PDCP header, and a payload. 
         [0108]      FIG. 11  illustrates operations of a terminal in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0109]    Referring to  FIG. 11 , the terminal receives a message instructing to establish a second connection using a second RAT from a first access node in operation  1101 . The first access node is a network entity wirelessly communicating using a first RAT. That is, the terminal can support both of the first RAT and the second RAT and establish the multiple connections using both of the first RAT and the second RAT. For example, the first RAT can conform to the cellular communication standard, and the second RAT can conform to the WLAN communication standard. That is, the terminal establishes the first connection with the first access node using the first RAT and is further instructed to establish the second connection with the second access node. The message can include at least one of identification information for the second connection (e.g., secondary cell ID), information indicating the bearer to be serviced in the second connection, and necessary information (e.g., identification information, encryption information, operating frequency, beacon interval) for accessing the second access node. 
         [0110]    In operation  1103 , the terminal can signal with the second access node to establish the connection. That is, the terminal sends a signal for establishing the connection to the second access node. More specifically, the terminal can send at least one of a signal for scanning the second access node, a signal for requesting the authentication from the second access node, and a signal for requesting the association with the second access node, and receive at least one response for the transmitted signal. Herein, the scanning signal can include identification information of the second access node. 
         [0111]    Next, although not depicted in  FIG. 11 , the terminal transmits and receives data in the multiple connections including the first connection and the second connection. In so doing, the payload of the data received in the second connection can include a packet of the first RAT. 
         [0112]    Although not depicted in  FIG. 11 , before the operation  1101 , the terminal can provide the first access node with the scanning result of at least one access node using the second RAT or the signal quality measurement result per remote antenna of the first access node. Hence, the first access node can determine to provide the second connection via the second access node. 
         [0113]    Although not depicted in  FIG. 11 , the terminal can transmit identification information for the terminal, relating to the second RAT to the first access node. The terminal identification information can be used for the second access node to determine whether to permit the access. 
         [0114]      FIG. 12  illustrates operations of a first access node in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0115]    Referring to  FIG. 12 , the first access node sends a message instructing to establish the second connection using the second RAT, to the terminal in operation  1201 . The first access node is a network entity wirelessly communicating using the first RAT. That is, the first access node can provide the multiple connections by controlling the second access node supporting the second RAT. For example, the first RAT can conform to the cellular communication standard, and the second RAT can conform to the WLAN communication standard. That is, the first access node establishes the first connection with the terminal using the first RAT and further instructs to establish the second connection with the second access node. The message can include at least one of the identification information for the second connection (e.g., secondary cell ID), the information indicating the bearer to be serviced in the second connection, and the necessary information (e.g., identification information, encryption information, operating frequency, beacon interval) for accessing the second access node. 
         [0116]    In operation  1203 , the first access node can transmit and receive data to and from the terminal via the second access node. That is, the first access node transmits and receives a part of the data directly in the first connection and the remaining data via the second access node. For example, the first access node can transmit and receive data for at least one of bearers allocated to the terminal, via the second access node. Alternatively, the first access node can transmit and receive a part of data for one bearer via the second access node. 
         [0117]    Although not depicted in  FIG. 12 , before the operation  1201 , the first access node can determine whether to provide the multiple connections to the terminal. That is, the first access node can determine whether to instruct the terminal to establish the second connection. For example, the first access node can determine whether to provide the multiple connections based on at least one of the class of the bearer allocated to the terminal and the terminal communication quality. 
         [0118]    Although not depicted in  FIG. 12 , before the operation  1201 , the first access node can receive from the terminal, the result of scanning at least one access node using the second RAT or the result of measuring the signal quality per remote antenna of the first access node. Hence, the first access node can determine to provide the second connection via the second access node. 
         [0119]    Although not depicted in  FIG. 12 , the first access node can receive the terminal identification information with respect to the second RAT. The first access node can provide the terminal identification information to the second access node so that the second access node can determine whether to permit the access based on the terminal identification information. 
         [0120]    Although not depicted in  FIG. 12 , the first access node can determine whether to activate/deactivate the second access node. For example, the first access node can determine whether to activate/deactivate the second access node based on at least one of the multi-connection supportability of the accessing terminal and the load level. When the status of the second access node needs to change, the first access node can send the message for turning on/off to the second access node. 
         [0121]    Although not depicted in  FIG. 12 , the first access node can determine whether to terminate the multiple connections of the terminal. That is, the first access node can determine whether to instruct the terminal to release the second connection. For example, the first access node can determine whether to terminate the multiple connections based on at least one of the packet loss rate of the second connection, the MCS level of the second connection, the channel quality of the second connection, and the communication quality of the first connection. In this case, the first access node can send the message instructing to release the second connection. 
         [0122]    Although not depicted in  FIG. 12 , the first access node can perform the dynamic scheduling while both the first connection and the second connection are provided to the terminal. For example, the first access node can distribute the data transmitted to the terminal, to the first connection and the second connection based on at least one of the loads of the first access node and the second access node, the signal strengths of the first access node and the second access node in relation to the terminal, the data type transmitted to the terminal, the calling plan of the terminal user, the terminal subscription information, the location of the second access node, and the crowded time zone. 
         [0123]      FIG. 13  illustrates operations of a second access node in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0124]    Referring to  FIG. 13 , the second access node signals to establish the second connection with the terminal in operation  1301 . The second access node is the network entity wirelessly communicating using the second RAT. That is, the second access node receives the signal for the connection establishment from the terminal. More specifically, the second access node can receive at least one of the signal for scanning the second access node, the signal for requesting the authentication from the second access node, and the signal for requesting the association with the second access node, and send at least one response for the received signal. Herein, the scanning signal can include the identification information of the second access node. 
         [0125]    In operation  1303 , the second access node forwards data between the first access node and the terminal using the second RAT. That is, the second access node can relay the data between the first access node and the terminal using the second RAT. The first access node is the network entity wirelessly communicating using the first RAT. For example, the first RAT can conform to the cellular communication standard, and the second RAT can conform to the WLAN communication standard. That is, the second access node can provide the second connection using the second RAT under the control of the first access node. The payload of the data transceived with the terminal in the second connection can include the packet conforming to the first RAT. 
         [0126]    Although not depicted in  FIG. 13 , before the operation  1301 , the second access node can receive the terminal identification information from the first access node. When the access to the second access node is requested, the second access node can determine whether or not the terminal requests the access based on identification information included in the request signal, and thus reject the request of other terminal than the terminal. 
         [0127]    Although not depicted in  FIG. 13 , the second access node can receive the message instructing to change the status, that is, to turn on/off from the first access node. The second access node can change the status according to the instruction of the message. For example, when the turn-off is instructed, the second access node can deactivate all or a part of the functions. 
         [0128]      FIG. 14  is a block diagram of a terminal in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0129]    Referring to  FIG. 14 , the terminal includes a Radio Frequency (RF) unit  1410 , a baseband unit  1420 , a storage  1430 , and a controller  1440 . 
         [0130]    The RF unit  1410  transmits and receives signals over a radio channel through signal band conversion and amplification. That is, the RF unit  1410  up-converts a baseband signal fed from the baseband unit  1420  to an RF signal, transmits the RF signal over an antenna, and down-converts an RF signal received over the antenna to a baseband signal. For example, the RF unit  1410  can include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a Digital-to-Analog Converter (DAC), and an Analog-to-Digital Converter (ADC). While only one antenna is depicted in  FIG. 14 , the terminal can include a plurality of antennas. The RF unit  1410  can include a plurality of RF chains. The RF unit  1410  can conduct beamforming. For the beamforming, the RF unit  1410  can adjust a phase and a magnitude of the signals transmitted and received over the antennas or antenna elements. 
         [0131]    The baseband unit  1420  converts a baseband signal and a bit stream according to a physical layer standard of the system. For example, for the data transmission, the baseband unit  1420  generates complex symbols by encoding and modulating the transmit bit stream. For the data reception, the baseband unit  1420  restores the received bit stream by demodulating and decoding the baseband signal fed from the RF unit  1410 . For example, in a data transmission based on Orthogonal Frequency Division Multiplexing (OFDM), the baseband unit  1420  generates the complex symbols by encoding and modulating the transmit bit stream, maps the complex symbols to subcarriers, and generates OFDM symbols using Inverse Fast Fourier Transform (IFFT) and Cyclic Prefix (CP) addition. In the data reception, the baseband unit  1420  splits the baseband signal fed from the RF unit  1410  into OFDM symbols, restores the signals mapped to the subcarriers using Fast Fourier Transform (FFT), and restores the received bit stream by demodulating and decoding the signals. 
         [0132]    As such, the baseband unit  1420  and the RF unit  1410  transmit and receive the signals. Thus, the baseband unit  1420  and the RF unit  1410  can be referred to as a transmitter, a receiver, a transceiver, a communication unit, or any other similar and/or suitable name for an element that transmits and/or receives signals. Further, at least one of the baseband unit  1420  and the RF unit  1410  can include a plurality of communication modules for supporting different RATs. At least one of the baseband unit  1420  and the RF unit  1410  can include different communication modules for processing signals of different frequency bands. For example, the different RATs can include the WLAN (e.g., IEEE 802.11), the cellular network (e.g., LTE), and so on. The different frequency bands can include a Super High Frequency (SHF) (e.g., 2.5 GHz, 5 GHz) band and a millimeter (mm) wave (e.g., 60 GHz) band. 
         [0133]    The storage  1430  stores a basic program for operating the terminal, an application program, and data such as setting information. The storage  1430  store the information about the second access node which wirelessly communicates using the second RAT. The storage  1430  provides the stored data according to a request of the controller  1440 . 
         [0134]    The controller  1440  controls the operations of the terminal. For example, the controller  1440  sends and receives the signals through the baseband unit  1420  and the RF unit  1410 . In addition, the controller  1440  records and reads data in the storage  1430 . For doing so, the controller  1440  can include at least one processor. For example, the controller  1440  can include a Communication Processor (CP) for controlling the communication and an application processor for controlling a higher layer such as application program. The controller  1440  includes a multi-connection processor  1442  for operating in a multi-connection mode. For example, the controller  1440  can control the terminal to serve as the terminal as shown in  FIGS. 2 ,  3 ,  4 ,  5 ,  7 ,  8 , and  9  and to perform the operations of  FIG. 11 . The controller  1440  operates as follows. 
         [0135]    The controller  1440  receives the message instructing to establish the second connection using the second RAT from the first access node which wirelessly communicates using the first RAT. The message can include at least one of the identification information (e.g., secondary cell ID) of the second connection, the information indicating the bearer to be serviced in the second connection, and the necessary information (e.g., the identification information, the encryption information, the operating frequency, the beacon interval) for accessing the second access node. Hence, the controller  1440  signals with the second access node to establish the connection. More specifically, the controller  1440  can transmit at least one of the signal for scanning the second access node, the signal for requesting the authentication from the second access node, and the signal for requesting the association with the second access node, and receive at least one response for the transmitted signal. Next, the controller  1440  transmits and receives data in the multiple connections including the first connection and the second connection. In so doing, the payload of the data received in the second connection can include the packet of the first RAT. 
         [0136]    According to another embodiment of the present disclosure, the controller  1440  can provide the first access node with the scanning result of at least one access node using the second RAT or the signal quality measurement result per remote antenna of the first access node. According to yet another embodiment of the present disclosure, the controller  1440  can transmit the terminal identification information relating to the second RAT to the first access node. The terminal identification information can be used for the second access node to determine whether to permit the access. 
         [0137]      FIG. 15  is a block diagram of a first access node in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0138]    Referring to  FIG. 15 , the first access node includes an RF unit  1510 , a baseband unit  1520 , a backhaul communication unit  1530 , a storage  1540 , and a controller  1550 . 
         [0139]    The RF unit  1510  transmits and receives signals over a radio channel through the signal band conversion and amplification. That is, the RF unit  1510  up-converts a baseband signal fed from the baseband unit  1520  to an RF signal, transmits the RF signal over an antenna, and down-converts an RF signal received over the antenna to a baseband signal. For example, the RF unit  1510  can include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC. While only one antenna is depicted in  FIG. 15 , the first access node can include a plurality of antennas. The RF unit  1510  can include a plurality of RF chains. The RF unit  1510  can conduct the beamforming. For the beamforming, the RF unit  1510  can adjust a phase and a magnitude of the signals transmitted and received over the antennas or antenna elements. 
         [0140]    The baseband unit  1520  converts a baseband signal and a bit stream according to a physical layer standard of the first RAT. For example, for the data transmission, the baseband unit  1520  generates complex symbols by encoding and modulating the transmit bit stream. In the data reception, the baseband unit  1520  restores the received bit stream by demodulating and decoding the baseband signal fed from the RF unit  1510 . For example, in the data transmission based on the OFDM, the baseband unit  1520  generates the complex symbols by encoding and modulating the transmit bit stream, maps the complex symbols to subcarriers, and generates OFDM symbols using the IFFT and the CP addition. In the data reception, the baseband unit  1520  splits the baseband signal fed from the RF unit  1510  into OFDM symbols, restores the signals mapped to the subcarriers using the FFT, and restores the received bit stream by demodulating and decoding the signals. As such, the baseband unit  1520  and the RF unit  1510  transmit and receive the signals. Thus, the baseband unit  1520  and the RF unit  1510  can be referred to as a transmitter, a receiver, a transceiver, a communication unit, a wireless communication unit, or any other similar and/or suitable name for an element that transmits and/or receives signals. 
         [0141]    The backhaul communication unit  1530  provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit  1530  converts the bit stream to be sent from the first access node to other node, for example, to other access node or the core network, into the physical signal and converts the physical signal received from the other node into the bit stream. 
         [0142]    The storage  1540  stores a basic program for operating the first access node, an application program, and data such as setting information. Particularly, the storage  1540  can store the bearer information allocated to the accessing terminal and the measurement result reported from the accessing terminal. The storage  1540  can store the information for determining whether to provide or terminate the multiple connections of the terminal. The storage  1540  provides the stored data according to a request of the controller  1550 . 
         [0143]    The controller  1550  controls the operations of the first access node. For example, the controller  1550  sends and receives the signals through the baseband unit  1520 , the RF unit  1510 , or the backhaul communication unit  1530 . In addition, the controller  1550  records and reads data in the storage  1540 . For doing so, the controller  1550  can include at least one processor. For example, the controller  1550  can include a multi-connection controller  1552  for controlling to provide the multiple connections to the terminal. For example, the controller  1550  can control the first access node to serve as the BS as shown in  FIGS. 2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 , and  9  or to conduct the operations of  FIG. 12 . The controller  1550  operates as follows. 
         [0144]    The controller  1550  sends the message instructing to establish the second connection using the second RAT, to the terminal. The message can include at least one of the identification information (e.g., secondary cell ID) of the second connection, the information indicating the bearer to be serviced in the second connection, and the necessary information (e.g., the identification information, the encryption information, the operating frequency, the beacon interval) for accessing the second access node. Next, the controller  1550  transmits and receives a part of the data directly in the first connection using the baseband unit  1520  and the RF unit  1510  and the remaining data via the second access node using the backhaul communication unit  1530 . For example, the controller  1550  can transmit and receive the data for at least one of the bearers allocated to the terminal, via the second access node. Alternatively, the controller  1550  can transmit and receive a part of data for one bearer via the second access node. 
         [0145]    According to another embodiment of the present disclosure, the controller  1550  can determine whether to provide the multiple connections to the terminal. That is, the controller  1550  can determine whether to instruct the terminal to establish the second connection. For example, the controller  1550  can determine whether to provide the multiple connections based on at least one of the class of the bearer allocated to the terminal and the terminal cellular communication quality. 
         [0146]    According to yet another embodiment of the present disclosure, the controller  1550  can receive from the terminal, the result of scanning at least one access node using the second RAT or the result of measuring the signal quality per remote antenna of the first access node. Hence, the controller  1550  can determine to provide the second connection via the second access node. 
         [0147]    According to still another embodiment of the present disclosure, the controller  1550  can receive the terminal identification information with respect to the second RAT. The controller  1550  can provide the terminal identification information to the second access node using the backhaul communication unit  1530  so that the second access node can determine whether to permit the access based on the terminal identification information. 
         [0148]    According to a further embodiment of the present disclosure, the controller  1550  can determine whether to activate/deactivate the second access node. For example, the controller  1550  can determine whether to activate/deactivate the second access node based on at least one of the multi-connection supportability of the accessing terminal and the load level. When the status of the second access node needs to change, the controller  1550  can send the message for turning on/off to the second access node. 
         [0149]    According to a further embodiment of the present disclosure, the controller  1550  can determine whether to terminate the multiple connections of the terminal. That is, the controller  1550  can determine whether to instruct the terminal to release the second connection. For example, the controller  1550  can determine whether to terminate the multiple connections based on at least one of the packet loss rate of the second connection, the MCS level of the second connection, the channel quality of the second connection, and the communication quality of the first connection. In this case, the controller  1550  can send the message instructing to release the second connection. 
         [0150]    According to a further embodiment of the present disclosure, the controller  1550  can perform the dynamic scheduling while both of the first connection and the second connection are provided to the terminal. For example, the controller  1550  can distribute the data transmitted to the terminal, to the first connection and the second connection based on at least one of the loads of the first access node and the second access node, the signal strengths of the first access node and the second access node in relation to the terminal, the data type transmitted to the terminal, the calling plan of the terminal user, the terminal subscription information, the location of the second access node, and the crowded time zone. 
         [0151]      FIG. 16  is a block diagram of a second access node in a wireless communication system according to an exemplary embodiment of the present disclosure. 
         [0152]    Referring to  FIG. 16 , the second access node includes an RF unit  1610 , a baseband unit  1620 , a backhaul communication unit  1630 , a storage  1640 , and a controller  1650 . 
         [0153]    The RF unit  1610  transmits and receives signals over a radio channel through the signal band conversion and amplification. That is, the RF unit  1610  up-converts a baseband signal fed from the baseband unit  1620  to an RF signal, transmits the RF signal over an antenna, and down-converts an RF signal received over the antenna to a baseband signal. For example, the RF unit  1610  can include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC. While only one antenna is depicted in  FIG. 16 , the second access node can include a plurality of antennas. The RF unit  1610  can include a plurality of RF chains. The RF unit  1610  can conduct the beamforming. For the beamforming, the RF unit  1610  can adjust the phase and the magnitude of the signals transmitted and received via the antennas or antenna elements. 
         [0154]    The baseband unit  1620  converts a baseband signal and a bit stream according to a physical layer standard of the second RAT. For example, for the data transmission, the baseband unit  1620  generates complex symbols by encoding and modulating the transmit bit stream. For the data reception, the baseband unit  1620  restores the received bit stream by demodulating and decoding the baseband signal fed from the RF unit  1610 . For example, in the data transmission based on the OFDM, the baseband unit  1620  generates the complex symbols by encoding and modulating the transmit bit stream, maps the complex symbols to subcarriers, and generates OFDM symbols using the IFFT and the CP addition. For the data reception, the baseband unit  1620  splits the baseband signal fed from the RF unit  1610  into OFDM symbols, restores the signals mapped to the subcarriers using the FFT, and restores the received bit stream by demodulating and decoding the signals. As such, the baseband unit  1620  and the RF unit  1610  transmit and receive the signals. Thus, the baseband unit  1620  and the RF unit  1610  can be referred to as a transmitter, a receiver, a transceiver, a communication unit, a wireless communication unit, or any other similar and/or suitable name for an element that transmits and/or receives signals. 
         [0155]    The backhaul communication unit  1630  provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit  1630  converts the bit stream transmitted from the second access node to other node, for example, to other access node or the core network, into the physical signal and converts the physical signal received from the other node into the bit stream. 
         [0156]    The storage  1640  stores a basic program for operating the second access node, an application program, and data such as setting information. Particularly, the storage  1640  can store the bearer information allocated to the accessing terminal and the measurement result reported from the accessing terminal. The storage  1640  can store the information for determining whether to provide or terminate the multiple connections of the terminal. The storage  1640  provides the stored data according to a request of the controller  1650 . 
         [0157]    The controller  1650  controls the operations of the second access node. For example, the controller  1650  sends and receives the signals through the baseband unit  1620 , the RF unit  1610 , or the backhaul communication unit  1630 . In addition, the controller  1650  records and reads data in the storage  1640 . For doing so, the controller  1650  can include at least one processor. The controller  1650  includes a packet processor  1652  for processing the data transmitted and received to and from the terminal operating in the multi-connection mode. The packet processor  1652  can generate and analyze the second RAT packet including the first RAT packet as the payload. For example, the controller  1650  can control the second access node to serve as the AP as shown in  FIGS. 2 ,  3 ,  4 ,  5 ,  6 , and  9  or to conduct the operations of  FIG. 13 . The controller  1650  operates as follows. 
         [0158]    The controller  1650  signals to establish the second connection with the terminal. More specifically, the controller  1650  can receive at least one of the signal for scanning the second access node, the signal for requesting the authentication from the second access node, and the signal for requesting the association with the second access node, and send at least one response for the received signal. Next, the controller  1650  forwards data between the first access node and the terminal using the second RAT. In so doing, the payload of the data transceived with the terminal in the second connection can include the first RAT packet. 
         [0159]    According to another embodiment of the present disclosure, the controller  1650  can receive the terminal identification information from the first access node through the backhaul communication unit  1630 . When the access to the second access node is requested, the controller  1650  can determine whether the terminal requests the access based on identification information included in the request signal and thus reject the request of other terminal than the terminal. 
         [0160]    According to yet another embodiment of the present disclosure, the controller  1650  can receive the message instructing to change the status, that is, to turn on/off from the first access node through the backhaul communication unit  1630 . The controller  1650  can change the status according to the instruction of the message. For example, when the turn-off is instructed, the controller  1650  can deactivate all or a part of the functions. 
         [0161]    As set forth above, the multiple connections using the different RATs in the wireless communication system can provide a high-capacity and high-rate communication service. 
         [0162]    Embodiments of the present invention according to the claims and description in the specification can be realized in the form of hardware, software or a combination of hardware and software. 
         [0163]    Such software may be stored in a computer readable storage medium. The computer readable storage medium stores one or more programs (software modules), the one or more programs comprising instructions, which when executed by one or more processors in an electronic device, cause the electronic device to perform methods of the present invention. 
         [0164]    Such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a Read Only Memory (ROM), whether erasable or rewritable or not, or in the form of memory such as, for example, Random Access Memory (RAM), memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a Compact Disc (CD), Digital Video Disc (DVD), magnetic disk or magnetic tape or the like. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs comprising instructions that, when executed, implement embodiments of the present invention. Embodiments provide a program comprising code for implementing apparatus or a method as claimed in any one of the claims of this specification and a machine-readable storage storing such a program. Still further, such programs may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same. 
         [0165]    While the invention has been shown and described with reference to certain exemplary 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 invention as defined by the appended claims and their equivalents.