Patent Publication Number: US-10313931-B2

Title: Method and apparatus for determining base stations providing cooperative communication to a mobile station in a communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY 
     The present application is a continuation of U.S. patent application Ser. No. 14/164,039 filed Jan. 24, 2014, which is related to and claims the benefit under 35 U.S.C. § 119(a) of a Korean patent application filed in the Korean Intellectual Property Office on Jan. 25, 2013 assigned Serial No. 10-2013-0008897, all of which are incorporated herein by reference into the present disclosure as if fully set forth herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a method and an apparatus for determining base stations providing cooperative communication to a mobile station in a communication system. 
     BACKGROUND 
     A wireless communication system has been rapidly developed. Particularly, due to various demands of users, the wireless communication system required to support a high speed and large capacity data service is being developed. Accordingly, in order to support such a large capacity data service, the wireless communication system considers using a high frequency band such as a millimeter wave. 
     Further, a communication system in which a plurality of base stations cooperate with each other and provide a service to a Mobile Station (MS), that is, a communication system using a multi-base station cooperation scheme is currently proposed and research on the communication system is continuously being progressed. 
     However, in general, when a high frequency band is used, it is highly likely to generate a large loss of a link between a Mobile Station (MS) and a Base Station (BS) and a rapid change in intensity of a received signal. 
     Accordingly, a method of providing more efficient communication to the MS in the high frequency band is required. 
     SUMMARY 
     To address the above-discussed deficiencies, it is a primary object to provide a method and an apparatus for determining BSs providing cooperative communication to an MS in a communication system. 
     The present disclosure provides conditions for selecting and determining BSs providing cooperative communication to an MS in a communication system and a method and an apparatus for operating the same. 
     In accordance with an aspect of the present disclosure, a method of determining member Base Stations (BSs) providing cooperative communication to a Mobile Station (MS) in a communication system is provided. The method includes: when a candidate list of the member BSs generated using at least one of strengths of signals received from adjacent BSs and cell loading state information of the adjacent BSs is received from the MS, selecting candidate BSs having a service quality larger than or equal to a threshold from candidate BSs included in the candidate list as targets to receive a member negotiation; and performing a capability negotiation with each of the selected targets to receive the member negotiation to select final member BSs and transmitting information on the determined final member BSs to the MS. 
     In accordance with another aspect of the present disclosure, a method of determining member Base Stations (BSs) providing cooperative communication to a Mobile Station (MS) in a communication system is provided. The method includes: generating a candidate list of the member BSs by using at least one of strengths of signals received from adjacent BSs and cell loading state information of the adjacent BSs; and transmitting the candidate list to a serving BS. 
     In accordance with another aspect of the present disclosure, a serving Base Station (BS) determining member BSs providing cooperative communication to a Mobile Station (MS) in a communication system is provided. The serving BS includes: a controller that, when recognizing a candidate list of member BSs generated using at least one of strengths of signals received from adjacent BSs and cell loading state information of the adjacent BSs from the MS, selects candidate BSs having a service quality larger than or equal to a threshold among candidate BSs included in the candidate list as targets to receive a member negotiation, performs a capability negotiation with each of the selected targets to receive the member negotiation to determine final member BSs, and controls to transmit information on the determined final member BSs to the MS through a transceiver. 
     In accordance with another aspect of the present disclosure, a Mobile Station (MS) determining member Base Stations (BSs) providing cooperative communication to the MS in a communication system is provided. The MS includes: a controller that generates a candidate list of the member BSs by using at least one of strengths of signals received from adjacent BSs and cell loading state information of the adjacent BSs and controls a transceiver to transmit the candidate list to a serving BS. 
     The present disclosure provides a method of selecting BSs providing cooperative communication to an MS in a communication system, thereby improving whole system performance of the communication system. 
     Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: 
         FIG. 1  illustrates a structure of a communication system according to an embodiment of the present disclosure; 
         FIG. 2  illustrates an example of a flowchart of an overall operation for determining BSs providing cooperative communication to an MS according to an illustrative embodiment of the present disclosure; 
         FIG. 3  illustrates an example of a flowchart of an operation in which an MS configures a candidate BS list according to an illustrative embodiment of the present disclosure; 
         FIG. 4A  illustrates an example of a flowchart of an overall operation in which a serving BS determines member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 4B  illustrates an example of a flowchart of an operation before a serving BS receives a candidate BS list from an MS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIGS. 4C and 4D  illustrate an example of a flowchart of a detailed operation for determining a target to receive a member BS negotiation among the operation of the serving BS according to an illustrative embodiment of the present disclosure; 
         FIG. 4E  illustrates an example of a flowchart of a detailed operation for performing a transaction negotiation with a target to receive a member BS negotiation for a cooperative communication-based cell among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 4F  illustrates an example of a flowchart of a detailed operation for determining a final member BS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 5  illustrates an example of a flow diagram of an overall operation for updating member BSs included in a cooperative communication-based cell of an MS according to an illustrative embodiment of the present disclosure; 
         FIG. 6  illustrates an example of a flowchart of an overall operation in which a serving BS determines member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 7A  illustrates an example of a flowchart of an overall operation in which a serving BS determines member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 7B  illustrates an example of a flowchart of a detailed operation for determining a candidate BS list among the overall operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 7C  illustrates an example of a flowchart of a detailed operation for performing a member BS negotiation among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 7D  illustrates an example of a flowchart of a detailed operation for determining a final member BS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 8  illustrates an example of a flowchart of operations of an MS according to an illustrative embodiment of the present disclosure; 
         FIG. 9  illustrates an example of a flow diagram of an overall operation for updating member BSs included in a cooperative communication-based cell of an MS according to an illustrative embodiment of the present disclosure; 
         FIG. 10  illustrates an example of a flowchart of an overall operation in which a serving BS determines member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 11  illustrates an example of a flowchart of an operation in which an MS configures a candidate BS list according to an illustrative embodiment of the present disclosure; 
         FIG. 12A  illustrates an example of a flowchart of an overall operation in which a serving BS determines member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 12B  illustrates an example of a flowchart of an operation before a serving BS receives a candidate BS list from an MS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 12C  illustrates an example of a flowchart of a detailed operation of a primary filtering operation using cell loading state information among the operation of the serving BS according to an illustrative embodiment of the present disclosure; 
         FIGS. 12D and 12E  illustrate an example of a flowchart of a detailed operation for performing a secondary filtering on primarily filtered candidate BSs and determining targets to receive a member BS negotiation among the operation of the serving BS according to an illustrative embodiment of the present disclosure; 
         FIG. 12F  illustrates an example of a flowchart of a detailed operation for performing a transaction negotiation with a target to receive a member BS negotiation for a cooperative communication-based cell among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 12G  illustrates an example of a flowchart of a detailed operation for determining a final member BS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure; 
         FIG. 13  illustrates an example of a flow diagram of an overall operation for updating member BSs configuring a cooperative communication-based cell of an MS according to an illustrative embodiment of the present disclosure; 
         FIG. 14  illustrates an example of a schematic configuration of an MS according to an embodiment of the present disclosure; and 
         FIG. 15  illustrates a schematic configuration of a serving BS according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 through 15 , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system or device. Hereinafter exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, it should be noted that only a part required for understanding operations according to the present disclosure is described and other parts are omitted so as not to make the subject matter of the present disclosure unclear. 
     The present disclosure provides conditions for determining BSs providing cooperative communication to an MS in a communication system and a method of operating the conditions. Further, a case where a cooperative communication-based cell provided by the present disclosure is configured and re-configured can be applied to all of cases where the MS performs an initial network entry process, wakes up from an idle mode and then performs a network re-entry process, and performs a connected mode operation. 
       FIG. 1  illustrates a structure of a cooperative communication-based cell according to an embodiment of the present disclosure. 
     Referring to  FIG. 1 , a cooperative communication-based cell  100  includes member BSs providing cooperative communication to an MS  110 . For example, the member BSs include a serving BS  102  and cooperative BS#1, BS#2, and BS#3  104 ,  106 , and  108 . The member BSs of the cooperative communication-based cell  100 , that is, the serving BS  102  and cooperative BS#1, BS#2, and BS#3  104 ,  106 , and  108  participate in data transmission to the MS  110  through a multi-BS cooperation scheme. Although a case where there are three cooperative BSs is described herein as an example, the number of cooperative BSs has no limitation. The serving BS is determined as a BS which the MS initially accesses. Thereafter, the serving BS may be selected as a member BS which satisfies at least one or all of conditions based on strength of a signal transmitted/received to/from the MS, BS load, and BS power (for example, a battery level or the like) from all the member BSs. 
     Hereinafter the present disclosure provides conditions for selecting and determining the member BSs providing the cooperative communication to the MS and a detailed operation for the conditions. 
     Hereinafter, in this illustrative embodiment of the present disclosure, the MS generates a candidate BS list including candidate BSs of the member BSs providing the cooperative communication to the MS based on measurement information of adjacent BSs to be scanned by the MS and transmits the generated candidate BS list to the serving BS. Then, the serving BS finally determines member BSs based on the candidate BSs included in the candidate BS list. 
       FIG. 2  is a flow diagram illustrating an overall operation for determining the member BSs configuring the cooperative communication-based cell of the MS according to an illustrative embodiment of the present disclosure. For the convenience of description, a serving BS  202  configuring the cooperative communication-based cell of an MS  200  has been already determined and adjacent BSs managed by the serving BS  302  are, for example, two BSs including adjacent BS#1  204  and BS#2  206 . However, the number of adjacent BSs managed by the serving BS may be different from the example of  FIG. 2  in practice. 
     Referring to  FIG. 2 , in steps  210   a  to  210   b , the serving BS  202  managing the cooperative communication-based cell of the MS  200  performs a fronthaul establishment process with adjacent BSs, for example, adjacent BS#1  204  and adjacent BS#2  206  to acquire in advance BS information of the corresponding adjacent BSs from adjacent BS#1  204  and adjacent BS#2  206 . The fronthaul refers to a link directly established for communication for the serving BS and each of the adjacent BSs. The BS information of the adjacent BSs refers to corresponding BS positions and basic capability. The BS position includes a position of the corresponding BS from each of the MS  200  and the serving BS  202 , a number of BSs located between BSs determined based on the corresponding BS (hereinafter referred to as a “hop”), and a hop count between the corresponding BS and a data gateway. The basic capability corresponds to remaining battery power which can be statistically calculated for the corresponding BS, buffering capacity, and antenna information. The antenna information corresponds to a number of available antennas of the corresponding BS, a number of Radio Frequency (RF) chains of the BS, a number of transmission/reception beams of the BS, and indication information on an optimal transmission/reception beam. In step  215 , the MS  200  determines candidate BSs satisfying a predetermined candidate BS determination condition from adjacent BSs included in a scanning BS set and configures a candidate BS list by the candidate BSs. The scanning BS set may include the serving BS of the MS  200 , adjacent BSs received from the serving BS, or adjacent BSs which can be scanned through recognition by the MS  200  without the aid of the serving BS. The candidate BS determination condition may include, for example, a condition in which strength of a signal received from each of the adjacent BSs included in the scanning BS set is larger than or equal to a predetermined signal strength or a condition in which cell loading state information is larger than or equal to a preset cell load threshold to support communication within the cooperative communication-based cell. A detailed description of the candidate BS determination condition will be made with reference to  FIG. 3 . In another example, parameters used for the candidate BS determination condition may include BS basic setting information which the MS  200  can acquire, for example, information on a maximum buffer size, a maximum number of antennas, a maximum number of RF chains, and a maximum number of beams. Further, the candidate BS determination condition may use information required for expecting a degree of a service to be received by the MS through the corresponding BS. 
     In step  220 , the MS  200  transmits the candidate BS list to the serving BS  202 . The candidate BS list may be inserted into an access request message and the access request message may be transmitted. An operation of the MS for generating the candidate BS list will be also described in detail with reference to  FIG. 3 . 
     In step  225 , the serving BS  202  determines a number of member BSs configuring the cooperative communication-based cell of the MS  200 . The number of member BSs is defined as a total number of cooperative BSs except for the serving BS  202 . The number of member BSs corresponds to a number of BSs which does not increase complexity of an operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS  200 . 
     In step  230 , the serving BS  202  calculates service quality which can be used within the cooperative communication-based cell by using BS information acquired from each of adjacent BS#1  204  and adjacent BS#2  206  included in the candidate BS list. For the convenience of description, it is assumed that adjacent BS#1  204  and adjacent BS#2  206  correspond to the candidate BSs included in the candidate BS list. However, hereinafter the candidate BSs included in the candidate BS list are defined as adjacent BSs which are included in the adjacent BSs of the serving BS  202  and satisfy the candidate BS determination condition of step  215  among the adjacent BSs. 
     In step  235 , the serving BS  202  identifies whether the service quality calculated for each of the candidate BSs, that is, adjacent BS#1  204  and adjacent BS#2  206  is larger than or equal to a predetermined service quality threshold. In step  240 , the serving BS  202  determines, for example, adjacent BS#1  204  having the service quality larger than or equal to the service quality threshold as a target to receive a member BS negotiation as a result of the identification. Then, in step  245 , the serving BS  202  performs the member BS negotiation with adjacent BS#1  204 . When the member BS negotiation is successfully performed, the serving BS  202  determines adjacent BS#1  204  as a final member BS in step  250 . In the member BS negotiation, the serving BS  202  makes, to adjacent BS#1  204 , a request for a BS capability state required when adjacent BS#1  204  operates as the member BS within the cooperative communication-based cell of the MS  200 . For example, the BS capability state includes a channel state between the corresponding BS and the serving BS  202  (for example, Received Signal Strength Indication (RSSI), path loss and the like), a number of available antennas of the corresponding BS, currently remaining power, available buffer capacity, current cell load, and a number of available RF chains. Further, when the serving BS  202  receives a response satisfying a required BS capability state from adjacent BS#1  204 , the member BS negotiation is successfully performed. 
     In step  255 , the serving BS  202  transmits information related to the final member BS to the MS  200 . The information related to the final member BS includes information informing that adjacent BS#1  204  is determined as the final member BS and information on the final member BS, that is, indication information of adjacent BS#1  204 . The information may be transmitted through an access response to the access request. Although it has been described that the final member BS is only adjacent BS#1  204 , if a number of final member BSs is plural, the indication information can be configured in a form of a list of the plurality of final member BSs. An operation for determining the member BS according to this illustrative embodiment of the present disclosure performed through steps  220  to  225  as described above will be described in more detail with reference to  FIGS. 4A to 4E . 
       FIG. 3  is a flowchart of an operation in which the MS configures the candidate BS list according to an illustrative embodiment of the present disclosure. 
     Referring to  FIG. 3 , in step  300 , the MS selects candidate BSs satisfying the candidate BS determination condition from adjacent BSs included in the scanning BS set. Then, the MS determines a temporary candidate BS list including the selected candidate BSs. For example, it is assumed that the candidate BS determination condition is satisfied when strength of a signal received from each of the adjacent BSs included in the scanning BS set is larger than or equal to a predetermined signal strength threshold. The signal strength corresponds to, for example, a Signal Interference and Noise Ratio (SINR), a Signal to Noise Ratio (SNR), an RSSI or the like. In step  305 , the MS acquires cell loading state information on each of the candidate BSs included in the temporary candidate BS list through a broadcasting channel. The cell loading state information may be indicated by an amount of resources used by the corresponding candidate BS or an amount of available resources. When it is assumed that the cell loading state information indicates the amount of the used resources, the amount of the resources may be indicated by, for example, an absolute value such as a number of used carriers. 
     When the cell loading state information indicates the amount of the used resources, the MS performs a cell loading state identification process of comparing the amount of the used resource indicated by the cell loading state information of the corresponding candidate BS with a predetermined threshold of used resources (hereinafter referred to as a “cell load maximum value”). Through the identification process, only for candidate BSs using the amount of the resources larger than or equal to the cell load maximum value, the MS performs step  315 . The MS deletes the candidate BSs using the resources larger than or equal to the cell load maximum value from the temporary candidate BS list in step  315  and proceeds to step  325 . 
     Through the identification process, for candidate BSs using the amount of the resources smaller than the cell load maximum value, the MS performs step  320  to continuously maintain the candidate BSs in the temporary candidate BS list and proceeds to step  325 . 
     In another example, it is assumed that the cell loading state information indicates the amount of available resources. In this event, in step  310 , the MS may perform the cell loading state identification process of comparing the amount of the available resources indicated by the cell loading state information of the corresponding BS with a predetermined threshold of an amount of available resources (hereinafter referred to as a “cell load minimum value”). In step  320 , the MS continuously maintain candidate BSs which use the resources larger than or equal to the cell load minimum value within the temporary candidate BS list among the candidate BSs. In step  315 , the MS deletes candidate BSs which use the resources smaller than the cell load minimum value from the temporary candidate BS list among the candidate BSs. 
     In step  325 , the MS identifies whether the cell loading state information identification process is performed for all the candidate BSs selected in step  300 . As a result of the identification, when the cell loading state information identification process is not performed for all the candidate BSs, the MS returns to step  310 . Then, the MS performs the cell loading state information identification process for the next candidate BS. 
     As a result of the identification, when the cell loading state information identification process is performed for all the candidate BSs, the MS reflects the cell loading state information identification process to configure the candidate BS list by the selected candidate BSs and transmits the configured candidate BS list to the serving BS in step  330 . The candidate BS list may be inserted into an access request message and the access request message may be transmitted. 
     The process of  FIG. 3  as described above may be equally applied to update the member BSs of the cooperative communication-based cell in a state where the cooperative communication-based cell of the MS has been already configured, and the temporary candidate BS list may be inserted into an adjacent BS report message and the adjacent BS report message may be transmitted. 
       FIG. 4A  illustrates an example of a flowchart of an overall operation in which the serving BS determines the member BSs according to this illustrative embodiment of the present disclosure. 
     Referring to  FIG. 4A , the serving BS identifies whether the candidate BS list is received from the MS in step  400 . As described above, the candidate BS list includes adjacent BSs satisfying the candidate BS determination condition among the adjacent BSs included in the scanning BS set as the candidate BSs. For example, the candidate BS determination condition may include a condition in which strength of a signal received from each of the adjacent BSs included in the scanning BS set is larger than or equal to a predetermined signal strength threshold or a condition in which cell loading state information satisfies a comparison result of a cell load threshold to support communication within the cooperative communication-based cell. As described above, the cell loading state information may indicate the amount of the available resources of the corresponding BS or the amount of the used resources. When the cell loading state information indicates the amount of the available resources of the corresponding BS, the candidate BS determination condition includes the condition in which the amount of the available resources of the corresponding BS is larger than or equal to the cell load minimum value. When the cell loading state information indicates the amount of the used resources of the corresponding BS, the candidate BS determination condition includes the condition in which the amount of the available resources of the corresponding BS is smaller than the cell load maximum value. 
     One or more parameters used for the candidate BS determination condition may be randomly selected by the MS or the parameter may be set to a default by the MS. When two or more parameters are selected, a case where conditions according to the two or more parameters are all satisfied or a case where only at least one of conditions according to the two or more parameters is satisfied may be set as an option of the candidate BS determination condition. When the MS acquires capability information of the corresponding BS through a signal broadcasted by the BS, the MS may determine whether the capability information of the BS is sufficient to support the communication of the MS. When the MS determines that the capability information of the BS is sufficient to support the communication of the MS, the MS may include the capability information of the BS in the candidate BS determination parameter. 
     As a result of the identification, when the candidate BS list is not received, the serving BS waits until the candidate BS list is received. 
     As a result of the identification, when the candidate BS list is received, the serving BS determines a number of member BSs configuring the cooperative communication-based cell of the MS in step  405 . In step  410  (A), the serving BS calculates service quality by using BS information acquired during the fronthaul establishment process with each of the candidate BSs included in the candidate BS list and then determines candidate BSs having service quality larger than or equal to a predetermined service quality threshold as targets to receive the member BS negotiation. The threshold of the service quality will be described below in detail with reference to  FIG. 4C . As described above, the BS information includes the BS position and basic capability which the serving BS acquires during the fronthaul establishment process with the corresponding BS. 
     Specifically, the serving BS calculates service quality of each of the candidate BSs included in the candidate BS list, for example, Equation (1) below by using the BS information acquired through the fronthaul establishment process with each of the candidate BSs.
 
Service quality=weightfactor 1*BS capability supporting cooperative communication-based cell operation+weightfactor 2*BS position supporting cooperative communication-based cell operation  (1)
 
     When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability corresponds to a number of antennas, required transmission power, required buffer capacity, and required RF chains. The BS position corresponds to a hop count between BSs satisfying latency required within the cooperative-communication-based cell, corresponding BS position from the MS and the serving BS, a path loss between BSs, and strength of a signal received by the serving BS. The preset reference corresponds to, for example, required throughput, a value of service quality, a minimum threshold of signal strength for serving the MS, a threshold of a difference between strengths of signals which the MS receives from the serving BS and the corresponding BS to be measured. 
     Meanwhile, when the cooperative communication-based cell is re-configured, MS mobility may be also used as a member BS negotiation condition. The MS mobility corresponds to information on a movement speed or movement direction of the MS. 
     In step  415  (B), the serving BS performs transaction negotiation with each of the determined targets to receive the member BS negotiation. The transaction negotiation refers to communication for identifying updated states of targets to receive the member BS negotiation. When the BS operates as the member BS configuring the cooperative communication-based cell of the MS, the transaction negotiation refers to identification of a required channel state, identification of BS load, and identification of throughput required for servicing the MS. 
     In step  420  (C), the serving BS determines candidate BSs having successfully passed through the transaction negotiation as the final member BSs among the targets to receive the member BS negotiation. When the number of final member BSs is smaller than a predetermined number of member BSs, the serving BS may further select candidate BSs from the candidate BSs, which do not satisfy the service quality threshold, included in the candidate BS list in order starting from highest service quality until the number of final member BSs reaches the predetermined number of member BS. The selected candidate BS is required to satisfy the BS position capability supporting the operation of the cooperative communication-based cell. 
     Meanwhile, when there is no final member BS determined in step  420  (C), that is, when a total number of final member BSs is “0”, the serving BS selects candidate BSs, which do not satisfy the service quality threshold, corresponding to the predetermined number of member BSs in order starting from highest service quality. The selected candidate BS is required to satisfy the BS position capability supporting the operation of the cooperative communication-based cell. 
     In another embodiment, when the number of final member BSs exceeds the number of member BSs, the serving BS may select again final member BSs corresponding to the number of member BSs from the final member BSs in order starting from highest service quality. 
     In step  425 , the serving BS transmits information related to the determined final member BSs to the MS. 
     Hereinafter, each of the operations in which the serving BS determines the member BSs according to this illustrative embodiment of the present disclosure will be described in more detail with reference to  FIGS. 4B to 4E . 
       FIG. 4B  is a flowchart of an operation before the serving BS receives the candidate BS list from the MS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. 
     Referring to  FIG. 4B , in step  395 , the serving BS performs a process of acquiring BS information on adjacent BSs through the fronthaul establishment process with each of the corresponding adjacent BSs. Among the BS information, BS information corresponding to candidate BSs included in the candidate BS list is used for determining candidate BSs to receive the member BS negotiation. In step  400 , the serving BS waits for a determination on whether to receive the candidate BS list from the MS. According to whether the serving BS receives the candidate BS list in step  400 , the serving BS operates equally to steps  405  to  425  of  FIG. 4A , so that a detailed description thereof will be omitted. 
       FIGS. 4C and 4D  are an example of a flowchart of a detailed operation for determining the target to receive the member BS negotiation among the operation of the serving BS according to an illustrative embodiment of the present disclosure. That is,  FIGS. 4C and 4D  are a flowchart of a detailed operation of step  410  (A) of  FIG. 4A . 
     Referring to  FIG. 4C , in step  432 , the serving BS identifies BS information on each of the candidate BSs included in the candidate BS list among the BS information pre-acquired during the fronthaul establishment process with the adjacent BSs. It is assumed that the BS information corresponds to the above mentioned BS basic capability and position information and the candidate BSs correspond to some of the adjacent BSs having established the fronthaul with the serving BS. In step  434 , the serving BS calculates service quality for each of the candidate BSs by using the acquired BS information and Equation (1) above. 
     Hereinafter through steps  436  to  444 , the serving BS determines whether to maintain the candidate BSs as members of the candidate BS list to re-configure the candidate BS list. Specifically, in step  436 , the serving BS compares service quality of one of the candidate BSs with a preset service quality threshold. The service quality corresponds to, for example, throughput required within the cooperative communication-based cell, Quality of Experience (QoE), and Quality of Service (QoS). The service quality is determined through a parameter indicating the BS capability and a parameter indicating the BS position. When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability corresponds to a number of required antennas, required transmission power, required buffer capacity, and required RF chains. The BS position corresponds to a hop count between BSs satisfying latency required within the cooperative-communication-based cell, corresponding BS position from each of the MS and the serving BS, a path loss between BSs, and strength of a signal received by the serving BS. The MS mobility may be also considered as the parameter indicating the service quality of the candidate BS. 
     Through a result of the comparison, the serving BS maintains the candidate BS satisfying the service quality threshold, that is, the candidate BS having the service quality larger than or equal to the service quality threshold as the member BS of the candidate BS list in step  438  and proceeds to step  446  ( a ). The serving BS proceeds to step  440  for the candidate BSs which do not satisfy the service quality threshold, that is, the candidate BSs having the service quality smaller than the service quality threshold (hereinafter referred to as “temporary candidate BSs”). In step  440 , the serving BS identifies whether position information of each of the temporary candidate BS satisfies a BS position threshold. As a result of the identification, when the position information of each of the temporary candidate BSs is within the BS position threshold, the serving BS proceeds to step  442 . More specifically, the position information of each of the temporary candidate BSs may be calculated by a distance from the MS. In this event, the BS position threshold may be indicated by a threshold of the distance from the MS. Alternatively, the BS position threshold may be calculated by a distance between the serving BS and the BS (for example, hop count) and may be indicated by a path loss or signal strength between the serving BS and the BS. The serving BS configures a potential candidate BS list by the temporary candidate BSs within the BS position threshold in step  442  and proceeds to step  446 . As a result of the identification, when there are the temporary candidate BSs having position information which is not within the BS position threshold, the serving BS removes the temporary candidate BSs having the position information which is not within the BS position threshold from the candidate BS list in step  444  and proceeds to step  446 . 
     In step  446 , the serving BS identifies whether all the candidate BSs included in the candidate BS list are determined to be maintained as the members of the candidate BS list, that is, whether service quality of all the candidate BSs are completely identified through steps  436  to  444 . As a result of the identification, when there is a candidate BS of which service quality has not been identified, the serving BS proceeds to step  436 . Then, until it is determined as to whether to maintain a next candidate BS as the member of the candidate BS list and thus all the candidate BSs are determined as to whether to be maintained as the members of the candidate BS list, steps  436  to  444  are repeated. 
     As a result of the identification, when all the candidate BSs are completely determined as to whether to be maintained as the members of the candidate BS list, the serving BS identifies whether a total number of candidate BSs included in the re-configured candidate BS list (hereinafter referred to as a number of re-configured candidate BSs) is larger than or equal to a preset number of member BSs in step  448 ( a ) of  FIG. 4D . As a result of the identification, when the total number of re-configured candidate BSs is larger than or equal to the number of member BSs, the serving BS selects as many re-configured candidate BSs as the number of member BSs in order starting from highest service quality and determines the selected candidate BSs as targets to receive the member BS negotiation in step  450 . The serving BS performs transaction negotiation with the targets to receive the member BS negotiation for the cooperative communication-based cell in step  456 , determines candidate BSs having successfully passed through the transaction negotiation as final member BSs in step  462 , and proceeds to step  464 . The transaction negotiation will be described in detail with reference to  FIG. 4E . 
     As a result of the identification, when the total number of re-configured candidate BSs is smaller than the number of member BSs, the serving BS identifies whether the total number of re-configured candidate BSs is “0” in step  452 . As a result of the identification, when the total number of re-configured BSs is not “0”, the serving BS selects as many candidate BSs as the number lacking from the BSs included in the potential candidate BS list in order starting from highest service quality and determines the selected candidate BSs as the targets to receive the member BS negotiation in step  454 . The serving BS performs the transaction negotiation with the selected targets to receive the member BS negotiation for the cooperative communication-based cell in step  456  and proceeds to step  462 . 
     As a result of the identification, when the total number of re-configured candidate BSs is “0”, the serving BS selects candidate BSs corresponding to the number of member BSs from the potential candidate BS list in order starting from highest service quality and determines the selected candidate BSs as the targets to receive the member BS negotiation. The serving BS performs the transaction negotiation with the selected targets to receive the member BS negotiation for the cooperative communication-based cell in step  456  and proceeds to step  462 . 
     In step  462 , the serving BS determines candidate BSs having successfully passed through the transaction negotiation as the final member BSs. In step  464 , the serving BS performs a member BS update operation of transmitting information on the final member BSs to the MS and the final member BSs. 
       FIG. 4E  is a flowchart of a detailed operation for performing the transaction negotiation with the targets to receive the member BS negotiation for the cooperative communication-based cell among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. That is,  FIG. 4E  is a flowchart of a detailed operation of step  415  (B) of  FIG. 4A . 
     Referring to  FIG. 4E , in step  466  (B), the serving BS identifies whether each of the candidate BSs included in the candidate BS list is determined as the target to receive the member BS negotiation. Since the operation of determining the candidate BSs as the target to receive the member BS negotiation overlaps the description of  FIGS. 4C and 4D , a detailed description will be omitted herein. 
     As a result of the identification, for the candidate BSs determined as the targets to receive the member BS negotiation, the serving BS configures a BS capability request message of making a request for BS capability required for communication in the cooperative communication-based cell in step  468  and proceeds to step  472 . When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability request message includes a number of required antennas, required transmission power, required buffer capacity, and required RF chains as the BS capability. 
     In step  472 , the serving BS transmits the BS capability request message of the corresponding BS to each of the candidate BSs determined as the targets to receive the member BS negotiation. In step  474 , the serving BS waits to receive a BS capability response message corresponding to the BS capability request message from the corresponding candidate BSs. The BS capability request message includes parameters indicating the BS capability required for servicing the MS, that is, a number of antennas of the BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. Meanwhile, as a result of the identification in step  466 , for the candidate BSs which are not determined as the targets to receive the member BS negotiation, the serving BS proceeds to step  469 . That is, candidate BSs satisfying the BS position threshold among the candidate BSs, which are not determined as the targets to receive the member BS negotiation may be selected as the members of the potential candidate BS list. The potential candidate BS list includes candidate BSs which do not satisfy the service quality threshold but satisfy the BS position threshold among the candidate BSs included in the candidate BS list received from the MS. Further, when the total number of re-configured candidate BSs is “0” as described in step  458  or when the total number of re-configured candidate BSs is smaller than the number of member BSs as described in step  454 , the potential candidate BS list stores candidate BSs, which can be additionally selected as the targets to receive the member BS negotiation, corresponding to the number lacking. Accordingly, the serving BS identifies whether the candidate BSs which have not been determined as the targets to receive the member BS negotiation among the candidate BSs in step  466  correspond to the members of the potential candidate BS list in step  469 . The serving BS configures the BS capability request message of making a request for the BS capability required for communication in the cooperative communication-based cell only for each of the identified candidate BSs included in the potential candidate BS list in step  470  and proceeds to step  472 . 
       FIG. 4F  is an example of a flowchart of a detailed operation for determining the final member BSs among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. That is,  FIG. 4F  is a flowchart of a detailed operation of step  420  (C) of  FIG. 4A . 
     Referring to  FIG. 4F , in step  476 , the serving BS receives a BS capability response message from the targets to receive the member BS negotiation having received the capability request message. The BS capability response message includes parameters indicating the capability of the corresponding candidate BS, that is, a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. 
     In step  478 , the serving BS analyzes parameters included in the BS capability response message received from each of the targets to receive the member BS negotiation. For example, the serving BS identifies whether a condition in which the currently remaining power of the corresponding BS is larger than or equal to a predetermined power threshold is satisfied or a condition in which cell load of the corresponding BS is smaller than a cell load threshold is satisfied. The conditions may be set according to a comparison between at least one of the parameters and a threshold corresponding to the parameter as well as the currently remaining power and the cell load. 
     As a result of the identification, when there is at least one candidate BS which is not included in the conditions, the serving BS removes the candidate BS which is not included in the conditions from a list of the targets to receive the member BS negotiation in step  480 . 
     As a result of the identification, when there is the candidate BS satisfying the conditions, the serving BS identifies whether service quality of the corresponding BS is larger than or equal to a predetermined BS service quality threshold in step  482 . Through a result of the identification, the serving BS also removes the candidate BSs having the BS service quality which does not satisfy the BS service quality threshold among the candidate BSs satisfying the conditions from the list of the targets to receive the member BS negotiation in step  408 . 
     When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability which is the parameter used for identifying the service quality of the BS corresponds to a number of required antennas, required transmission power, required buffer capacity, and required RF chains. The BS position corresponds to a hop count between BSs satisfying latency required within the cooperative-communication-based cell, a corresponding BS position from each of the MS and the serving BS, a path loss between BSs, and strength of a signal received by the serving BS. The MS mobility may be also considered as the parameter indicating the service quality of the candidate BS. 
     Through a result of the identification, the serving BS determines the candidate BSs having the BS capability satisfying the service quality threshold among the candidate BSs satisfying the conditions as the member BSs in step  484 . In step  486 , the serving BS identifies whether a total number of determined member BSs is larger than a predetermined number of member BSs. As a result of the identification, when the total number of determined member BSs is smaller than or equal to the number of member BSs, the serving BS proceeds to step  490 . 
     As a result of the identification, when the total number of determined member BSs is larger than the predetermined number of member BSs, the serving BS selects only as many member BSs as the predetermined number of member BSs from the determined member BSs in order starting from highest service quality in step  488 . In step  490 , the serving BS determines the selected member BSs as the final member BSs. 
       FIG. 5  is an example of a flow diagram illustrating an overall operation for updating the member BSs configuring the cooperative communication-based cell of the MS according to an illustrative embodiment of the present disclosure. For the convenience of description, it is assumed that a serving BS  502  configuring the cooperative communication-based cell of an MS  500  updates adjacent BS#2  506  in a state where the serving BS  502  finally determines adjacent BS#1  504  as a member BS, that is, a cooperative BS like in  FIG. 2 . 
     Referring to  FIG. 5 , in steps  510   a  to  510   b , the serving BS  502  performs a fronthaul establishment process for a communication link with each of the adjacent BSs of the serving BS  502 , for example, adjacent BS#1  504  and adjacent BS#2  506 . The fronthaul establishment process is performed before the cooperative communication-based cell of the MS  500  is configured and updated. Through the fronthaul establishment process, the serving BS  502  has acquired BS information of adjacent BS#1  504  and adjacent BS#2  506 . Since the BS information indicates the corresponding BS position and basic capability and a detailed description thereof overlaps the description in  FIG. 2 , the detailed description thereof will be omitted herein. 
     The MS  500  measures strength of a signal received from each of the adjacent BSs included in the scanning BS set in step  515  and transmits information on the measured strength of the signal to the serving BS  502  as a result of the MS measurement in step  520 . 
     Thereafter, the serving BS  502  identifies that one of signal strengths acquired from the result of the MS measurement, for example, signal strength of adjacent BS#2  506  exceeds a minimum signal strength threshold for serving the MS in step  525 . Then, the serving BS  502  determines a member BS update for adding adjacent BS#2  506  as the member BS configuring the cooperative communication-based cell of the MS  500 . Although it has been described as an example that only adjacent BS#2  506  is updated as a new member BS, a number of member BSs to be updated can be changed. 
     In step  530 , the serving BS  502  calculates service quality by using the BS information of adjacent BS#2  506  acquired during the fronthaul establishment process of step  510   b.    
     In step  535 , the serving BS  502  identifies whether the calculated service quality of adjacent BS#2  506  is larger than or equal to a service quality threshold available within the cooperative communication-based cell in step  535 . In step  540 , the serving BS  502  determines, for example, adjacent BS#2  506  having the service quality larger than or equal to the service quality threshold as a target to receive a member BS negotiation. 
     Then, in step  545 , the serving BS  502  performs the member BS negotiation with adjacent BS#2  506 . When the member BS negotiation is successfully performed, the serving BS  502  determines adjacent BS#2  506  as a new member BS in step  550 . In the member BS negotiation, the serving BS  502  makes, to adjacent BS#2  506 , a request for a BS capability state required when adjacent BS#2  506  operates as the member BS within the cooperative communication-based cell of the MS  500 . Further, when the serving BS  506  receives a response satisfying the required BS capability state, the member BS negotiation is successfully performed. 
     In step  555 , the serving BS  502  transmits cooperative communication-based cell update information informing that adjacent BS#2  506  has been determined as the new member BS to the MS  500 . The MS  500  having received the cooperative communication-based cell update information stores adjacent BS#2  506  in a cooperative communication-based cell member list managed by the MS  500  as a new cooperative BS. In step  560 , the serving BS  502  transmits the cooperative communication-based cell update information to adjacent BS#1  504  corresponding to the existing member BS. 
     In step  565 , the serving BS  502  informs adjacent BS#2  506  that the member BS update process has been completed. 
     Meanwhile, although it has been described in  FIG. 5  as an example that the member BS update process is performed by adding a new cooperative BS, the member BS update process according to an embodiment of the present disclosure may be expanded to a case where the existing member BS is removed or the serving BS is changed to the existing or new member BS. 
     Hereinafter, in another illustrative embodiment of the present disclosure, the serving BS transmits information on primarily filtered adjacent BSs to the MS based on the BS information of each of the adjacent BSs having established the fronthaul. Then, the MS measures strengths of signals received from only the filtered adjacent BSs instead of the adjacent BSs included in the existing scanning BS set, configures a candidate BS list by the selected candidate BSs based on a result of the measurement, and transmits the configured candidate BS list to the serving BS. Thereafter, the serving BS selects BSs to receive the member negotiation from the candidate BSs based on the received signal strength measurement of the MS and finally determines the member BSs through the transaction negotiation for the cooperative communication-based cell. 
       FIG. 6  is a flowchart of an overall operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. For the convenience of description, a serving BS  602  configuring the cooperative communication-based cell of an MS  600  has been already determined and adjacent BSs managed by the serving BS  602  are, for example, two BSs including adjacent BS#1  604  and BS#2  606 . However, the number of adjacent BSs managed by the serving BS may be different from the example of  FIG. 6  in practice. 
     Referring to  FIG. 6 , in steps  610   a  to  610   b , the serving BS  602  managing the cooperative communication-based cell of the MS  600  has performed a fronthaul establishment process with adjacent BSs of the serving BS  602 , for example, adjacent BS#1  604  and adjacent BS#2  606  to acquire BS information of the corresponding adjacent BSs in advance from adjacent BS#1  604  and adjacent BS#2  606 . Since the BS information of the adjacent BS indicates the corresponding BS position and basic capability and definitions thereof are identical to those in  FIG. 2 , a detailed description thereof will be omitted. 
     In step  615 , the serving BS  602  calculates service quality which can be used within the cooperative communication-based cell by using the BS information acquired from each of adjacent BS#1  604  and adjacent BS#2  606 . In step  620 , the serving BS  602  identifies whether the service quality calculated for each of the adjacent BSs, that is, adjacent BS#1  604  and adjacent BS#2  606  is larger than or equal to a predetermined service quality threshold. The service quality and the service quality threshold may be set equally to the embodiments discussed above with regard to  FIGS. 2-5  or set to have a range wider than that of the embodiments discussed above with regard to  FIGS. 2-5 . 
     In step  625 , the serving BS  602  configures a candidate BS list by adjacent BSs having service quality larger than or equal to the service quality threshold as a result of the identification. In step  630 , the serving BS  602  transmits the candidate BS list to the MS  600 . 
     Thereafter, the MS  600  having received the candidate BS list measures strengths of signals received from the candidate BSs included in the candidate BS list in step  635 . The MS  600  re-configures the candidate BS list by candidate BSs satisfying a predetermined candidate BS determination condition among the candidate BSs included in the candidate BS list based on the measured signal strengths. In step  640 , the MS  600  transmits the re-configured candidate BS list to the serving BS  602 . The re-configured candidate BS list may be transmitted to the serving BS  602  through, for example, an access request message. For example, it is assumed that the candidate BS determination condition of the MS  600  is set equally to the embodiments discussed above with regard to  FIGS. 2-5 . 
     Then, in step  645 , the serving BS  602  determines a number of member BSs included in the cooperative communication-based cell of the MS  600 . The number of member BSs is defined as a total number of cooperative BSs except for the serving BS  602 . The number of member BSs corresponds to a number of BSs which does not increase complexity of the operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS  600 . 
     In step  650 , the serving BS  602  determines candidate BSs included in the re-configured BS list as targets to receive a member BS negotiation. In step  655 , the serving BS  602  performs the member BS negotiation with the determined targets to receive the member BS negotiation in step  655 . For example, it is assumed that adjacent BS#1  604  is one of the candidate BSs. When the member BS negotiation with adjacent BS#1  601  is successfully performed, the serving BS  602  determines adjacent BS#1  604  as a final member BS in step  660 . In the member BS negotiation, the serving BS  602  makes, to adjacent BS#1  604 , a request for a BS capability state required when adjacent BS#1  604  operates as the member BS within the cooperative communication-based cell of the MS  600 . For example, the BS capability state includes a channel state between the corresponding BS and the serving BS  602  (for example, RSSI, path loss and the like), a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. Further, when the serving BS  604  receives a response satisfying the required BS capability state from adjacent BS#1  604 , the member BS negotiation is successfully performed. 
     In step  655 , the serving BS  602  transmits information related to the final member BS to the MS  600 . The information related to the final member BS includes information informing that adjacent BS#1  604  has been determined as the final member BS and information on the final member BS, that is, indication information of adjacent BS#1  604 . The information may be transmitted through an access response to the access request. Although it has been described that the final member BS is only adjacent BS#1  604 , if a number of final member BSs is plural, the indication information can be configured in a form of a list of the plurality of final member BSs. 
     As described above, the operation for determining the member BS according to this illustrative embodiment of the present disclosure which is performed through steps  610   a  to  625  and steps  645  to  660  will be described in detail with reference to  FIGS. 7A to 7F . 
       FIG. 7A  illustrates an example of a flowchart of an overall operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. 
     Referring to  FIG. 7A , in step  700 , the serving BS determines a candidate BS list by adjacent BSs having completed a fronthaul establishment with the serving BS by using information on the adjacent BSs acquired during a fronthaul establishment process. Since the BS information of the adjacent BSs indicates the corresponding BS position and basic capability and definitions thereof are identical to those in  FIG. 2 , a detailed description thereof will be omitted. The serving BS calculates service quality which can be used within the cooperative communication-based cell by using information having a static characteristic among the BS position information and basic capability of the adjacent BSs. The basic capability of the BS having the static characteristic corresponds to, for example, system information which is not changed in spite of a time change among the capability information of the BS. In this event, the serving BS identifies whether the calculated service quality of the adjacent BSs is larger than or equal to a predetermined service quality threshold. Through the identification of the service quality, the serving BS inserts adjacent BSs having the service quality larger than or equal to the service quality threshold into the candidate BS list. In step  705 , the serving BS transmits the candidate BS list to the MS. 
     In step  710 , the serving BS waits for a determination on whether to receive the candidate BS list from the MS. As a result of the waiting, when the candidate BS list is not received, the serving BS continuously maintains a standby state. 
     As a result of the waiting, when the candidate BS list is received, the serving BS determines a number of member BSs included in the cooperative communication-based cell of the MS in step  715 . The number of member BSs is defined as a total number of cooperative BSs except for the serving BS. The number of member BSs corresponds to a number of BSs which does not increase complexity of the operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS  200 . In step  720  (B), the serving BS determines the candidate BSs included in the candidate BS list as targets to receive the member BS negotiation and performs the member BS negotiation with the determined targets to receive the member BS negotiation. In the member BS negotiation, the serving BS  602  makes, to the BS corresponding to the target to receive the corresponding member BS negotiation, a request for a BS capability state required when the BS operates as the member BS within the cooperative communication-based cell of the MS. For example, the BS capability state includes a channel state between the corresponding BS and the serving BS (for example, RSSI, path loss and the like), a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. Further, when the serving BS receives a response satisfying the required BS capability state from adjacent BS#1  204 , the member BS negotiation is successfully performed. 
     In step  725  (C), the serving BS determines the candidate BSs having successfully passed through the member BS negotiation among the targets to receive the member BS negotiation as final member BSs. In step  730 , the serving BS transmits information related to the determined final member BSs to the MS. 
     The operation for determining the member BS according to this illustrative embodiment of the present disclosure performed through steps  720  to  730  as described above will be described in more detail with reference to  FIGS. 7B to 7F . 
       FIG. 7B  illustrates an example of a flowchart of a detailed operation for determining the candidate BS list among the overall operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. That is,  FIG. 7B  is a flowchart of a detailed operation of step  700  (A) of  FIG. 7A . 
     Referring to  FIG. 7B , in step  732 , the serving BS acquires in advance BS information of each of the adjacent BSs during the fronthaul establishment process with each of the adjacent BSs. In step  734 , the serving BS calculates service quality of each of the adjacent BSs by using the BS information of each of the adjacent BSs. The service quality corresponds to, for example, throughput, QoE, QoS and the like required for communication with the cooperative communication-based cell. The service quality is determined through a parameter indicating the BS capability and a parameter indicating the BS position. The BS capability includes a system parameter of the corresponding adjacent BS and corresponds to information which is not changed in spite of a time change, for example, maximum buffer capacity, a maximum number of RF chains, a maximum number of antennas, and maximum transmission power. The BS position corresponds to a hop count between BSs satisfying latency required within the cooperative-communication-based cell, a corresponding BS position from each of the MS and the serving BS, a path loss between BSs, and strength of a signal received by the serving BS. 
     In step  736 , the serving BS compares service quality of one of the adjacent BSs having fronthaul establishment with the serving BS with a preset threshold service quality threshold. As a result of the comparison, when the service quality of the adjacent BS is larger than or equal to the service quality threshold, the serving BS adds the adjacent BS as the member of the candidate BS list in step  738  and proceeds to step  746 . As a result of the comparison, when the service quality of the adjacent BS is smaller than the service quality threshold, the serving BS identifies whether position information of the adjacent BS satisfies a BS position threshold in step  740 . As a result of the identification, when the position information of the adjacent BS is within the BS position threshold, the serving BS proceeds to step  742 . More specifically, the position information of the adjacent BS may be calculated by a distance from the MS. In this event, the BS position threshold may be indicated by a threshold of the distance from the MS. Alternatively, the position information of the adjacent BS may be calculated by a distance (for example, hop count) between the serving BS and the adjacent BS or calculated by path load or signal strength between the serving BS and the adjacent BS. The serving BS adds the adjacent BS as the member of the candidate BS list in step  742  and proceeds to step  746 . As a result of the identification, when the adjacent BS is not located within the BS position threshold, the serving BS does not add the adjacent BS to the candidate BS list in step  744  and proceeds to step  746 . 
     In step  746 , the serving BS identifies whether it is determined that all the adjacent BSs having established the fronthaul with the serving BS are added as the member of the candidate BS list through steps  736  to  744 . As a result of the identification, when there is an adjacent BS which has not been determined as to whether to be added as the member of the candidate BS list, the serving BS proceeds to step  736 . Then, the serving BS repeats steps  736  to  744  until the next adjacent BS is determined as to whether to be added as the member of the candidate BS list and then all the adjacent BSs are determined as to whether to be added as the member of the candidate BS list. 
     As a result of the identification, when all the adjacent BSs are determined as to whether to be added as the member of the candidate BS list, the serving BS transmits the candidate BS list configured as described above to the MS in step  748 . 
       FIG. 7C  illustrates an example of a flowchart of a detailed operation for performing the member BS negotiation among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. That is,  FIG. 7C  is a flowchart of a detailed operation of step  720  (B) of  FIG. 7A . 
     Referring to  FIG. 7C , the serving BS waits for a determination on whether to receive the re-configured candidate BS list from the MS in step  750 . As a result of the waiting, when the re-configured candidate BS list is not received, the serving BS waits until the re-configured candidate BS list is received. The re-configured candidate BS list is made by selecting candidate BSs satisfying the candidate BS determination condition of the MS from the candidate BSs included in the candidate BS list which the MS receives from the serving BS. The re-configured candidate BS list will be described in detail with reference to a description of operations of the MS in  FIG. 8 . 
     As a result of the identification, when the re-configured candidate BS list is received, the serving BS determines the candidate BSs included in the re-configured candidate BS list as targets to receive the member BS negotiation in step  752 . The re-configured candidate BS list is determined by candidate BSs satisfying the candidate BS determination condition by the MS. It is assumed that the candidate BS determination condition is set equally to the embodiments discussed above with regard to  FIGS. 2-5 . 
     In step  754 , the serving BS performs the transaction negotiation with the targets to receive the member BS negotiation in step  754 . Specifically, the serving BS configures a BS capability request message of making a request for the BS capability of the corresponding BS to each of the candidate BSs determined as the targets to receive the member BS negotiation. When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability request message includes a number of required antennas, required transmission power, required buffer capacity, and required RF chains as the BS capability. 
     In step  756 , the serving BS waits to receive a BS capability response message corresponding to the BS capability request message from the corresponding candidate BSs. The BS capability response message includes parameters indicating the capability of the corresponding candidate BS, that is, a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. 
       FIG. 7D  is an example of a flowchart of a detailed operation for determining the final member BS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. That is,  FIG. 7D  is a flowchart of a detailed operation of step  725  (C) of  FIG. 7A . 
     Referring to  FIG. 7D , in step  758 , the serving BS receives a BS capability response message from the targets to receive the member BS negotiation having received the BS capability request message. The targets to receive the member BS negotiation correspond to candidate BSs included in the re-configured candidate BS list received from the MS. The BS capability response message includes parameters indicating the capability of the corresponding candidate BS, that is, a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. 
     In step  760 , the serving BS analyzes parameters included in the BS capability response message received from each of the targets to receive the member BS negotiation. For example, the serving BS identifies whether a condition in which the currently remaining power of the corresponding BS is larger than or equal to a predetermined power threshold is satisfied or a condition in which cell load of the corresponding BS is smaller than a cell load threshold is satisfied. The conditions may be set according to a comparison between at least one of the parameters and a threshold corresponding to the parameter as well as the currently remaining power and the cell load. As a result of the identification, when there is at least one candidate BS which is not included in the conditions, the serving BS removes the candidate BS which is not included in the conditions from a list of the targets to receive the member BS negotiation in step  762 . 
     As a result of the identification, when there is the candidate BS satisfying the conditions, the serving BS identifies whether service quality of the corresponding BS is larger than or equal to a predetermined BS service quality threshold in step  764 . Through a result of the identification, the serving BS also removes the candidate BSs having the BS service quality which does not satisfy the BS service quality threshold among the candidate BSs satisfying the conditions from the list of the targets to receive the member BS negotiation in step  762 . 
     When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability which is the parameter used for identifying the service quality of the BS corresponds to a number of required antennas, required transmission power, required buffer capacity, and required RF chains. The BS position corresponds to a hop count between BSs satisfying latency required within the cooperative-communication-based cell, a corresponding BS position from each of the MS and the serving BS, a path loss between BSs, and strength of a signal received by the serving BS. The MS mobility may be also considered as the parameter indicating the service quality of the candidate BS. Through a result of the identification, the serving BS determines the candidate BSs having the BS capability satisfying the service quality threshold among the candidate BSs satisfying the conditions as the member BSs in step  766 . In step  768 , the serving BS identifies whether a total number of determined member BSs is larger than a predetermined number of member BSs. As a result of the identification, when the total number of determined member BSs is smaller than or equal to the number of member BSs, the serving BS proceeds to step  772 . 
     As a result of the identification, when the total number of determined member BSs is larger than the predetermined number of member BSs, the serving BS selects only as many member BSs as the predetermined number of member BSs from the determined member BSs in order starting from highest service quality in step  770 . In step  772 , the serving BS determines the selected member BSs as the final member BSs. 
       FIG. 8  illustrates an example of a flowchart of the operation of the MS according to an illustrative embodiment of the present disclosure. 
     Referring to  FIG. 8 , in step  800 , the MS waits until the candidate BS list is received from the serving BS. The serving BS configures the candidate BS list by adjacent BSs having service quality larger than or equal to a service quality threshold through steps  610   a  to  625  of  FIG. 6 . 
     In step  805 , the MS acquires cell loading state information or signal strength from each of the candidate BSs included in the candidate BS list. In step  810 , the MS identifies whether the cell loading state information and the signal strength of each of the candidate BSs satisfies the candidate BS determination condition. For example, it is assumed that the candidate BS determination condition is set equally to the embodiments discussed above with regard to  FIGS. 2-5 . 
     Through a result of the identification, the MS removes candidate BSs which do not satisfy the candidate BS determination condition from the candidate BS list in step  815 . Through a result of the identification, the MS maintains candidate BSs satisfying the candidate BS determination condition within the candidate BS list in step  820 . 
     In step  825 , the MS identifies whether all the candidate BSs included in the candidate BS list are determined as to satisfy the candidate BS determination condition. As a result of the identification, when there is a candidate BS which has not been identified as to whether it satisfies the candidate BS determination condition, the MS returns to step  810  and identifies whether a next candidate BS satisfies the candidate BS determination condition. 
     As a result of the identification, when all the candidate BSs are identified as to whether they satisfy the candidate BS determination condition, the MS determines the candidate BSs satisfying the candidate BS determination condition as the final candidate BSs in step  830  and transmits information on the determined final candidate BSs to the serving BS as the re-configured candidate BS list. The information on the re-configured candidate BSs may be transmitted through, for example, an access request message. 
       FIG. 9  illustrates an example of a flow diagram of an overall operation for updating the member BSs configuring the cooperative communication-based cell of the MS according to an illustrative embodiment of the present disclosure. For the convenience of description, it is assumed that a serving BS  902  configuring the cooperative communication-based cell of an MS  900  updates adjacent BS#2  906  in a state where the serving BS  902  finally determines adjacent BS#1  904  as a member BS, that is, a cooperative BS. 
     Referring to  FIG. 9 , in steps  910   a  to  910   b , the serving BS  902  performs a fronthaul establishment process for a communication link with each of the adjacent BSs of the serving BS  902 , for example, adjacent BS#1  904  and adjacent BS#2  906 . The fronthaul establishment process is performed before the cooperative communication-based cell of the MS  900  is configured and updated. It is assumed that the serving BS  902  has acquired BS information of adjacent BS#1  904  and adjacent BS#2  906  through the fronthaul establishment process. Since the BS information indicates the corresponding BS position and basic capability and a detailed description thereof overlaps the description in  FIG. 2 , the detailed description thereof will be omitted herein. 
     In step  915 , the serving BS  902  calculates service quality which can be used within the cooperative communication-based cell by using the BS information acquired from each of adjacent BS#1  904  and adjacent BS#2  906 . In step  920 , the serving BS  902  identifies whether the service quality calculated for each of the adjacent BSs, that is, adjacent BS#1  904  and adjacent BS#2  906  is larger than or equal to a predetermined service quality threshold. The service quality and the service quality threshold may be set equally to the embodiments discussed above with regard to  FIGS. 2-5  or set to have a range wider than that of the embodiments discussed above with regard to  FIGS. 2-5 . 
     In step  925 , the serving BS  902  configures a candidate BS list by adjacent BSs having service quality larger than or equal to the service quality threshold as a result of the identification. In step  930 , the serving BS  902  transmits the candidate BS list to the MS  900 . 
     Thereafter, the MS  900  having received the candidate BS list determines final candidate BSs satisfying the predetermined candidate BS determination condition among the candidate BSs included in the candidate BS list, configures a re-configured candidate BS list by the final candidate BSs, and transmits the re-configured candidate BS list to the serving BS  902  in step  935 . For example, it is assumed that the candidate BS determination condition is set equally to this illustrative embodiment. 
     Then, in step  940 , the serving BS  902  determines a number of member BSs configuring the cooperative communication-based cell of the MS  900  based on the re-configured candidate BSs. The number of member BSs is defined as a total number of cooperative BSs except for the serving BS  902 . The number of member BSs corresponds to a number of BSs which does not increase complexity of the operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS  900 . 
     In step  945 , the serving BS  902  determines candidate BSs included in the re-configured BS list as targets to receive a member BS negotiation. In step  950 , the serving BS  602  performs the member BS negotiation with the determined targets to receive the member BS negotiation in step  655 . In the member BS negotiation, the serving BS  902  makes, to the target to receive the member BS negotiation, a request for a BS capability state required when the target operates as the member BS within the cooperative communication-based cell of the MS. For example, the BS capability state includes a channel state between the corresponding BS and the serving BS  602  (for example, RSSI, path loss and the like), a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. Further, when the serving BS receives a response satisfying the required BS capability state from target to receive the member BS negotiation, the member BS negotiation is successfully performed. 
     Thereafter, in step  955 , the serving BS identifies battery or cell loading state information of the candidate member BS acquired during the member BS negotiation process to identify whether the battery or load information of the candidate member BS satisfies a battery or cell load threshold. The serving BS identifies service quality of the candidate member BS having a battery or cell load value satisfying the battery or cell load threshold. When the service quality of the candidate member BS satisfies a preset service quality threshold, the candidate member BS is determined as a new member BS. Accordingly, it is assumed that the serving BS  902  determines a member BS update to add adjacent BS#2  906  as the new member BS. In step  960 , the serving BS  902  transmits cooperative communication-based cell update information informing that adjacent BS#2  906  has been determined as the new member BS to the MS  900 . The MS  900  having received the cooperative communication-based cell update information stores adjacent BS#2  904  in a cooperative communication-based cell member list managed by the MS  900  as a new cooperative BS. In step  965 , the serving BS  902  transmits the cooperative communication-based cell update information to adjacent BS#1  904  corresponding to the existing member BS. In step  970 , the serving BS  902  informs adjacent BS#2  906  that the member BS update process has been completed. 
     Meanwhile, although it has been described in  FIG. 9  as an example that the member BS update process is performed by adding a new cooperative BS, the member BS update process according to an embodiment of the present disclosure may be expanded to a case where the existing member BS is removed or the serving BS is changed to the existing or new member BS. 
     In another illustrative embodiment of the present disclosure, the MS generates the candidate BS list including candidate BSs of member BSs configuring the cooperative communication-based cell of the MS based on strength of signals of received from adjacent BSs. Then, the serving BS finally determines member BSs based on the candidate BSs included in the candidate BS list. In this illustrative embodiment of the present disclosure, before filtering the candidate BSs included in the candidate BS list by using service quality, the serving BS further performs a filtering process using cell loading state information of the candidate BSs to finally determine member BSs of the candidate BSs having passed through a total of two filterings. 
       FIG. 10  illustrates an example of a flowchart of an overall operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. For the convenience of description, a serving BS  1002  configuring the cooperative communication-based cell of an MS  1000  has been already determined and adjacent BSs managed by the serving BS  1002  are, for example, adjacent BS#1  1004  and BS#2  1006 . However, the number of adjacent BSs managed by the serving BS may be different from the example of  FIG. 10  in practice. 
     Referring to  FIG. 10 , in steps  1010   a  to  1010   b , the serving BS  1002  managing the cooperative communication-based cell of the MS  1000  has performed a fronthaul establishment process with adjacent BSs of the serving BS  1002 , for example, adjacent BS#1  1004  and adjacent BS#2  1006  to acquire BS information of the corresponding adjacent BSs in advance from adjacent BS#1  1004  and adjacent BS#2  1006 . Since the BS information of the adjacent BS indicates the corresponding BS position and basic capability and definitions thereof are identical to those in  FIG. 2 , a detailed description thereof will be omitted. 
     In step  1011 , the serving BS  1002  communicates with a Self Optimized Network (SON) server  1008 . When an amount of available resources of a corresponding adjacent BS among the adjacent BSs having established the fronthaul with the serving BS  1002  through the communication with the SON server  1008  is smaller than a minimum cell load value or an amount of used resources is larger than or equal to a maximum cell load value, the serving BS  1002  may receive information indicating the impossibility of servicing a new MS any more due to an excessive cell loading state (hereinafter referred to as “additional access impossibility indication”). 
     In step  1012 , the MS  1000  determines candidate BSs satisfying a predetermined candidate BS determination condition among adjacent BSs included in a scanning BS set and configures a candidate BS list by the candidate BSs. For example, the candidate BS determination condition may include a condition in which strength of a signal received from each of the adjacent BSs included in the scanning BS set is larger than or equal to a predetermined signal strength threshold or a condition in which the amount of the available resources indicated by the cell loading state information is larger than or equal to the minimum cell load value or the amount of the used resources is smaller than the maximum cell load value. In step  1014 , the MS  1000  transmits the candidate BS list to the serving BS  1002 . The candidate BS list may be inserted into an access request message and the access request message may be transmitted. Since the operation of the MS for generating the candidate BS list overlaps operations of  FIGS. 3 and 11 , a detailed description thereof will be omitted. 
     In step  1016 , the serving BS  1002  determines a number of the member BSs configuring the cooperative communication-based cell of the MS  1000 . The number of member BSs is defined as a total number of cooperative BSs except for the serving BS  1002 . The number of member BSs corresponds to a number of BSs which does not increase complexity of the operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS  1000 . 
     In step  1018 , the serving BS  1002  performs a primary filtering by using the cell loading state information of the candidate BSs included in the candidate BS list. That is, when the serving BS  1002  receives the additional access impossibility indication of the corresponding candidate BS from the fronthaul established with each of the candidate BSs or the SON server  1008 , the serving BS  1002  removes the corresponding candidate BS from the candidate BS list. In step  1020 , the serving BS  1002  calculates service quality of each of the remaining candidate BSs (hereinafter referred to as “primarily filtered candidate BSs”) except for the candidate BSs of which the additional access possibility indication is received. For the convenience of description, it is assumed that the primarily filtered candidate BSs are adjacent BS#1  1004  and adjacent BS#2  1006 . Then, the serving BS  1002  calculates service quality of each of adjacent BS#1  1004  and adjacent BS#2  1006  by using BS information pre-acquired through the fronthaul establishment process with each of adjacent BS#1  1004  and adjacent BS#2  1006 . In step  1022 , the serving BS  1002  performs a secondary filtering for identifying whether the service quality calculated for each of the primarily filtered adjacent BSs, that is, adjacent BS#1  1004  and adjacent BS#2  1006  is larger than or equal to a predetermined service quality threshold. In step  1024 , the serving BS  1002  determines the candidate BS having service quality larger than or equal to the service quality threshold (hereinafter referred to as “secondarily filtered candidate BS”) as a target to receive a member BS negotiation among the primarily filtered candidate BSs. For the convenience of description, for example, it is assumed that adjacent BS#1  1004  is determined as the target to receive the member BS negotiation. Then, in step  1026 , the serving BS  1002  performs the member BS negotiation with adjacent BS#1  1004 . When the member BS negotiation is successfully performed, the serving BS  1002  determines adjacent BS#1  1004  as a final member BS in step  1028 . In the member BS negotiation, the serving BS  1002  makes, to adjacent BS#1  1004 , a request for a BS capability state required when adjacent BS#1  1004  operates as the member BS within the cooperative communication-based cell of the MS  1000 . For example, the BS capability state includes a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available chains. Further, when the serving BS  1002  receives a response satisfying the required BS capability state from adjacent BS#1  1004 , the member BS negotiation is successfully performed. 
     In step  1030 , the serving BS  1002  transmits information related to the final member BS to the MS  1000 . The information related to the final member BS includes information informing that adjacent BS#1  1004  has been determined as the final member BS and information on the final member BS, that is, indication information of adjacent BS#1  1004 . The information may be transmitted through an access response to the access request. Although it has been described that the final member BS is only adjacent BS#1  1004 , if a number of final member BSs is plural, the indication information can be configured in a form of a list of the plurality of final member BSs and then transmitted to the MS  1000 . 
       FIG. 11  is a flowchart of an operation in which the MS configures the candidate BS list according to an illustrative embodiment of the present disclosure. 
     Referring to  FIG. 11 , since operations of the MS in steps  1100  to  1130  are the same as the operations of  FIG. 3 , a detailed description thereof will be omitted herein. 
       FIG. 12A  is a flowchart of an overall operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. 
     Referring to  FIG. 12A , the serving BS identifies whether the candidate BS list is received from the MS in step  1200 . As described above, the candidate BS list includes adjacent BSs satisfying the candidate BS determination condition among the adjacent BSs included in the scanning BS set as the candidate BSs. For example, the candidate BS determination condition may include a condition in which strength of a signal received from each of the adjacent BSs included in the scanning BS set is larger than or equal to a predetermined signal strength threshold or a condition in which the amount of the available resources indicated by the cell loading state information is larger than or equal to the minimum cell load value or the amount of the used resources is smaller than the maximum cell load value. One or more parameters used for the candidate BS determination condition may be randomly selected by the MS or the parameter may be set to a default by a service provider. When two or more parameters are selected, a case where conditions according to the two or more parameters are all satisfied or a case where only at least one of conditions according to the two or more parameters is satisfied may be set as an option of the candidate BS determination condition. In another example, parameters may be used for the candidate BS determination condition when the MS acquires BS basic setting information, for example, information on a maximum buffer size, a maximum number of antennas, a maximum number of RF chains, and a maximum number of beams. Further, information required for expecting a degree of a service to be received by the MS through the corresponding BS may be also used for the candidate BS determination condition. As a result of the identification, when the candidate BS list is not received, the serving BS waits until the candidate BS list is received. 
     As a result of the identification, when the candidate BS list is received, the serving BS determines a number of member BSs configuring the cooperative communication-based cell of the MS in step  1202 . The number of member BSs is defined as a total number of cooperative BSs except for the serving BS. The number of member BSs corresponds to a number of BSs which does not increase complexity of the operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS. In step  1204  (A), the serving BS performs a primary filtering by using cell loading state information of each of the candidate BSs. That is, the serving BS receives the cell loading state information of the corresponding candidate BS through communication with the fronthaul established with each of the corresponding candidate BSs or the SON server and identifies whether the cell loading state information includes the “additional access impossibility indication”. As a result of the identification, the serving BS removes the candidate BSs having the cell loading state information including the additional access possibility indication from the candidate BS list to complete the primary filtering. 
     In step  1206 (B), the serving BS calculates service quality of each of the primarily filtered candidate BSs by using BS information acquired during the fronthaul establishment process with the serving BS and then performs a secondary filtering for selecting candidate BSs having service quality larger than or equal to a predetermined service quality threshold. Further, the serving BS determines the secondarily filtered candidate BSs as targets to receive the member BS negotiation. The service quality threshold may be described below in detail with reference to  FIG. 12C . As described above, the BS information includes the BS position and basic capability which the serving BS acquires during the fronthaul establishment process with the corresponding BS. Specifically, the serving BS calculates service quality of each of the candidate BSs included in the candidate BS list, for example, Equation (1) above by using the BS information acquired through the fronthaul establishment process with each of the candidate BSs. 
     Meanwhile, when the cooperative communication-based cell is re-configured, MS mobility may be also used as a member BS negotiation condition. The MS mobility corresponds to information on a movement speed or a movement direction of the MS. 
     In step  1208 (C), the serving BS performs the transaction negotiation with each of the targets to receive the member BS negotiation. The transaction negotiation refers to communication for identifying a BS capability state of each of the targets to receive the member BS negotiation. When the BS operates as the member BS configuring the cooperative communication-based cell of the MS, the transaction negotiation refers to identification of a required BS capability state, identification of BS cell load information, and identification of throughput required for servicing the MS. 
     In step  1210  (D), the serving BS determines candidate BSs having successfully passed through the transaction negotiation as the final member BSs among the targets to receive the member BS negotiation. When the number of final member BSs is smaller than a predetermined number of member BSs, the serving BS may further select candidate BSs which do not satisfy the service quality threshold from the candidate BSs included in the candidate BS list in order starting from highest service quality until the number of final member BSs reaches the predetermined number of member BSs. Meanwhile, when there is no final member BS determined in step  1210 , the serving BS selects candidate BSs, which do not satisfy the threshold of quality of service, corresponding to the predetermined number of member BSs from the candidate BSs in order starting from highest service quality. In another embodiment, when the number of final member BSs exceeds the number of member BSs, the serving BS may select again final member BSs corresponding to the number of member BSs from the final member BSs in order starting from highest service quality. 
     In step  1212 , the serving BS performs a member BS update for transmitting information on the determined final member BSs to the MS and the final member BSs. 
     Hereinafter each of the operations in which the serving BS determines the member BSs according to this illustrative embodiment of the present disclosure will be described in more detail with reference to  FIGS. 12B to 12F . 
       FIG. 12B  illustrates an example of a flowchart of an operation before the serving BS receives the candidate BS list from the MS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. 
     Referring to  FIG. 12B , in step  1195 , the serving BS performs a process of acquiring BS information on adjacent BSs through the fronthaul establishment process with each of the corresponding adjacent BSs. The BS information is used for the primary filtering for selecting members of the candidate BS list. In step  1200 , the serving BS waits to receive the candidate BS list from the MS. According to whether the serving BS receives the candidate BS list in step  1200 , the serving BS operates equally to steps  1202  to  1212  of  FIG. 12A , so that a detailed description thereof will be omitted. 
       FIG. 12C  illustrates an example of a flowchart of a detailed operation of a primary filtering operation using cell loading state information among the operation of the serving BS according to an illustrative embodiment of the present disclosure. That is,  FIG. 12C  is a detailed operation flowchart of step  1204  (A) of  FIG. 12A . 
     Referring to  FIG. 12C , in step  1214 , the serving BS identifies BS information acquired in advance during the fronthaul establishment process with adjacent BSs or BS information acquired from the SON server to identify whether there are candidate BSs having cell loading state information including the “additional access impossibility indication” among the candidate BSs included in the candidate BS list. 
     Through a result of the identification, the serving BS removes the candidate BSs having the cell loading state information including the additional access impossibility indication from the candidate BS list in step  1216  and proceeds to step  1220 . Through a result of the identification, the serving BS maintains the candidate BSs having the cell loading state information which does not include the additional access impossibility indication as the members of the candidate BS list in step  1218  and proceeds to step  1220 . In step  1220 , the serving BS identifies whether all the candidate BSs included in the candidate BS list have passed through the primary filtering as described in steps  1214  to  1218 . As a result of the identification, when there is a candidate BS which has not passed through the primary filtering, the serving BS proceeds to step  1214  to perform the primary filtering on a next candidate BS. As a result of the identification, when all the candidate BSs have passed through the primary filtering, the serving BS performs a secondary filtering on the primarily filtered candidate BSs. 
     As described above, in  FIGS. 12A to 12C , an example in which the serving BS performs the primary filtering on the candidate BSs by using the fronthaul establishment process with the adjacent BSs or the “additional access impossibility indication” included in the cell loading state information of the adjacent BSs acquired from the SON server has been described. 
     Alternatively, the serving BS does not separately perform the primary filtering after receiving the candidate BS list but performs the primary filtering during the process of generating the candidate BS list. Specifically, the MS receives the cell loading state information of the adjacent BSs included in the scanning BS set through a broadcasting channel. Then, when there are adjacent BSs having the cell loading state information including the “additional access impossibility indication”, the MS may exclude the adjacent BSs from the candidate BS list even though the adjacent BSs correspond to the candidate BSs satisfying the candidate BS determination condition and then transmit the candidate BS list to the serving BS. 
       FIGS. 12D and 12E  illustrate an example of a flowchart of a detailed operation for performing the secondary filtering on the primarily filtered candidate BSs and determining targets to receive a member BS negotiation among the operation of the serving BS according to an illustrative embodiment of the present disclosure. That is,  FIGS. 12D and 12E  are a flowchart of detailed operation of step  1206  (B) of  FIG. 12A . 
     Referring to  FIG. 12D , in step  1222 , the serving BS identifies BS information on each of the primarily filtered candidate BSs among the BS information pre-acquired during the fronthaul establishment process with the adjacent BSs. It is assumed that the BS information corresponds to the above mentioned BS basic capability and position information and the candidate BSs correspond to some of the adjacent BSs having established the fronthaul with the serving BS. In step  1224 , the serving BS calculates service quality for each of the candidate BSs by using the acquired BS information and Equation (1) above. 
     Hereinafter through steps  1224  to  1232 , the serving BS calculates service quality of each of the primarily filtered candidate BSs to perform the secondary filtering and determines whether to maintain the candidate BSs as members of the candidate BS list, so as to re-configure the candidate BS list. Specifically, in step  1224 , the serving BS compares service quality of one of the primarily filtered candidate BSs with a preset service quality threshold. The service quality corresponds to, for example, throughput, QoE, QoS and the like required for communication with the cooperative communication-based cell. The service quality is reflected through a parameter indicating the BS capability and a parameter indicating the BS position. When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability corresponds to a number of required antennas, required transmission power, required buffer capacity, and required RF chains. The BS position corresponds to a hop count between BSs satisfying latency required within the cooperative-communication-based cell, a corresponding BS position from each of the MS and the serving BS, a path loss between BSs, and strength of a signal received by the serving BS. The MS mobility may be also considered as the parameter indicating the service quality of the candidate BS. Through a result of the comparison, the serving BS maintains the candidate BS satisfying the service quality threshold, that is, the candidate BS having the service quality larger than or equal to the service quality threshold among the primarily filtered candidate BSs as the member BS of the candidate BS list in step  1226  and proceeds to step  1234 . After the comparison, the serving BS identifies whether position information of the candidate BSs which do not satisfy the service quality threshold, that is, the candidate BSs having the service quality smaller than the service quality threshold (hereinafter referred to as “temporary candidate BSs”) among the primarily filtered candidate BSs satisfies a BS position threshold in step  1228 . As a result of the identification, when the position information of each of the temporary candidate BSs is within the BS position threshold, the serving BS proceeds to step  1230 . More specifically, the position information of each of the temporary candidate BSs may be calculated by a distance from the MS. In this event, the BS position threshold may be indicated by a threshold of the distance from the MS. The serving BS configures a potential candidate BS list by the temporary candidate BSs in step  1230  and proceeds to step  1234 . As a result of the identification, when there are the temporary candidate BSs having the position information which is not within the BS position threshold, the serving BS removes the temporary candidate BSs having the position information which is not within the BS position threshold from the candidate BS list in step  1232  and proceeds to step  1234 . 
     In step  1234 , the serving BS identifies whether all the candidate BSs primarily filtered through steps  1224  to  1232  have been determined as to whether to be maintained as the members of the candidate BS list, that is, whether the secondary filtering has been performed on all the primarily filtered candidate BSs. As a result of the identification, when the secondary filtering has not been completely performed on the primarily filtered candidate BSs, the serving BS proceeds to step  1224 . Then, the serving BS determines whether to maintain a next candidate BS as the member of the candidate BS list and repeats steps  1224  to  1232  until the secondary filtering is completely performed on all the primarily filtered candidate BSs. 
     Referring to  FIG. 12E , as a result of the identification, when the secondary filtering has been completely performed on all the primarily filtered candidate BSs, the serving BS performs a comparison of whether a total number of secondarily filtered candidate BSs is larger than or equal to a preset number of member BSs ins step  1236 ( a ). As a result of the comparison, when the total number of secondarily filtered candidate BSs is larger than or equal to the number of member BSs, the serving BS determines the secondarily filtered candidate BSs corresponding to the number of member BSs as targets to receive the member BS negotiation in order starting from highest service quality in step  1240 . The serving BS performs the transaction negotiation for the cooperative communication-based cell with the selected targets to receive the member BS negotiation in step  1244  and proceeds to step  1250 . 
     As a result of the comparison, when the total number of secondarily filtered candidate BSs is smaller than the number of member BSs, the serving BS identifies whether the total number of secondarily filtered candidate BSs is “0” in step  1238 . As a result of the identification, when the total number of secondarily filtered BSs is not “0”, the serving BS selects a number of candidate BSs so as to fulfill the number of member BSs from the BSs included in the potential candidate BS list in order starting from highest service quality and determines the selected candidate BSs as the targets to receive the member BS negotiation in step  1242 . The serving BS performs the transaction negotiation for the cooperative communication-based cell with the selected targets to receive the member BS negotiation in step  1244  and proceeds to step  1250 . 
     As a result of the identification, when the total number of secondarily filtered candidate BSs is “0”, the serving BS selects candidate BSs corresponding to the number of member BSs from the potential candidate BS list in order starting from highest service quality and determines the selected candidate BSs as the targets to receive the member BS negotiation in step  1246  and proceeds to step  1244 . The serving BS performs the transaction negotiation for the cooperative communication-based cell with the selected targets to receive the member BS negotiation in step  1244  and proceeds to step  1250 . 
     In step  1250 , the serving BS determines candidate BSs having successfully passed through the transaction negotiation as the final member BSs. Further, in step  1250 , the serving BS performs a member BS update operation of transmitting information on the final member BSs to the MS and the final member BSs. 
       FIG. 12F  illustrates an example a flowchart of a detailed operation for performing the transaction negotiation for the cooperative communication-based cell with the targets to receive the member BS negotiation among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. That is,  FIG. 12E  is a flowchart of detailed operation of step  1208  (C) of  FIG. 12A . 
     Referring to  FIG. 12F , in step  1254  (C), the serving BS identifies whether the secondary filtering has been completely performed on the primarily filtered candidate BSs and the secondarily filtered candidate BSs have been determined as the targets to receive the member BS negotiation. Since the operation for identifying whether the primarily filtered candidate BSs have been determined as the targets to receive the member BS negotiation through the secondary filtering overlaps the description in  FIG. 12E , a detailed description thereof will be omitted herein. 
     As a result of the identification, for the candidate BSs determined as the targets to receive the member BS negotiation, the serving BS configures a BS capability request message of making a request for BS capability required for communication in the cooperative communication-based cell in step  1256  and proceeds to step  1260 . When the corresponding candidate BS operates as the member BS within the cooperative communication-based cell of the MS, the BS capability request message includes a number of required antennas, required transmission power, required buffer capacity, and required RF chains as the BS capability. 
     In step  1260 , the serving BS transmits the BS capability request message of the corresponding BS to each of the candidate BSs determined as the targets to receive the member BS negotiation. In step  1262 , the serving BS waits to receive a BS capability response message corresponding to the BS capability request message from the corresponding candidate BSs. The BS capability response message includes parameters indicating the capability of the corresponding candidate BS, that is, a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. 
     Meanwhile, through a result of the identification in step  1254 , among the candidate BSs which have not been determined as the targets to receive the member BS negotiation, candidate BSs satisfying the BS position threshold may be selected as the members of the potential candidate BS list. The potential candidate BS list includes candidate BSs which do not satisfy the service quality threshold but satisfy the BS position threshold among the primarily filtered candidate BSs. Further, when the total number of secondarily filtered candidate BSs is “0” or when the total number of secondarily filtered candidate BSs is smaller than the number of member BSs, the potential candidate BS list stores candidate BSs which can be additionally selected as the targets to receive the member BS negotiation to fill up the number of member BSs. Accordingly, the serving BS identifies whether the candidate BSs which have not been determined as the targets to receive the member BS negotiation among the candidate BSs identified in step  1254  correspond to the members of the potential candidate BS list in step  1257 . Further, for the identified members of the potential candidate BS list, the serving BS configures a BS capability request message of making a request for BS capability required for communication in the cooperative communication-based cell of the corresponding candidate BS in step  1258  and proceeds to step  1260 . 
       FIG. 12G  illustrates an example of a flowchart of a detailed operation for determining the final member BS among the operation in which the serving BS determines the member BSs according to an illustrative embodiment of the present disclosure. That is,  12 G illustrates an example of a flowchart of a detailed operation of step  1210 (D) of  FIG. 12A . 
     Referring to  FIG. 12G , in step  1264 , the serving BS receives a BS capability response message from the targets to receive the member BS negotiation having received the capability request message. The targets to receive the member BS negotiation refers to candidate BSs having completely passed through the primary filtering and the secondary filtering among the candidate BSs included in the candidate BS list transmitted by the MS according to this illustrative embodiment of the present disclosure. The BS capability response message includes parameters indicating the capability of the corresponding candidate BS, that is, a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available RF chains. 
     In step  1266 , the serving BS analyzes parameters included in the BS capability response message received from each of the targets to receive the member BS negotiation. For example, the serving BS identifies whether a condition in which the currently remaining power of the corresponding BS is larger than or equal to a predetermined power threshold is satisfied or a condition in which current cell load, that is, an amount of available resources is larger than or equal to a minimum cell load value or an amount of used resource is smaller than a maximum cell load value is satisfied. The conditions may be set according to a comparison between at least one of the parameters and a threshold corresponding to the parameter as well as the currently remaining power and the cell load. 
     As a result of the identification, when there is at least one candidate BS which is not included in the conditions, the serving BS removes the candidate BS which is not included in the conditions from a list of the targets to receive the member BS negotiation in step  1268 . 
     As a result of the identification, when there is the candidate BS satisfying the conditions, the serving BS identifies whether service quality of the corresponding BS is larger than or equal to a predetermined BS service quality threshold in step  1270 . Through a result of the identification, the serving BS also removes the candidate BSs having the BS service quality which does not satisfy the BS service quality threshold among the candidate BSs satisfying the conditions from the list of the targets to receive the member BS negotiation in step  1268 . 
     Through a result of the identification, the serving BS determines the candidate BSs having the BS service quality satisfying the service quality threshold among the candidate BSs satisfying the conditions as the member BSs in step  1272 . In step  1274 , the serving BS identifies whether a total number of determined member BSs is larger than a predetermined number of member BSs. As a result of the identification, when the total number of determined member BSs is smaller than or equal to the number of member BSs, the serving BS proceeds to step  1278 . As a result of the identification, when the total number of determined member BSs is larger than the predetermined number of member BSs, the serving BS selects only as many member BSs as the predetermined number of member BSs from the determined member BSs in order starting from highest service quality in step  1276 . In step  1278 , the serving BS determines the selected member BSs as the final member BSs. 
       FIG. 13  illustrates an example of a flow diagram of an overall operation for updating the member BSs configuring the cooperative communication-based cell of the MS according to an illustrative embodiment of the present disclosure. For the convenience of description, it is assumed that a serving BS  1302  configuring the cooperative communication-based cell of an MS  1300  updates adjacent BS#2  1306  as a new member BS in a state where the serving BS  1302  finally determines adjacent BS#1  1304  as a member BS, that is, a cooperative BS. 
     Referring to  FIG. 13 , in steps  1310   a  to  1310   c , the serving BS  1302  managing the cooperative communication-based cell of the MS  1300  has performed a fronthaul establishment process with adjacent BSs of the serving BS  1302 , for example, adjacent BS#1  1304  and adjacent BS#2  1306  to acquire BS information of the corresponding adjacent BSs in advance from adjacent BS#1  1304  and adjacent BS#2  1306 . Since the BS information of the adjacent BS indicates the corresponding BS position and basic capability and definitions thereof are identical to those in  FIG. 2 , a detailed description thereof will be omitted. 
     In step  1311 , the serving BS  1302  communicates with a Self Optimized Network (SON) server  1308 . The serving BS  1302  may receive an additional access impossibility indication of a corresponding adjacent BS of the adjacent BSs having established the fronthaul with the serving BS  1302  through the communication with the SON server  1308 . 
     In step  1312 , the MS  1300  determines candidate BSs satisfying a predetermined candidate BS determination condition among adjacent BSs included in a scanning BS set and configures a candidate BS list by the candidate BSs. For example, the candidate BS determination condition may include a condition in which strength of a signal received from each of the adjacent BSs included in the scanning BS set is larger than or equal to a predetermined signal strength threshold or a condition in which an amount of available resources indicated by cell loading state information is larger than or equal to a minimum cell load value or an amount of used resources is smaller than a maximum cell load value. In step  1314 , the MS  1300  transmits the candidate BS list to the serving BS  1302 . The candidate BS list may be inserted into an access request message and the access request message may be transmitted. Since the operation of the MS for generating the candidate BS list overlaps operations of  FIGS. 3 and 11 , a detailed description thereof will be omitted. 
     In step  1316 , the serving BS  1302  determines a number of the member BSs configuring the cooperative communication-based cell of the MS  1300 . The number of member BSs is defined as a total number of cooperative BSs except for the serving BS  1302 . The number of member BSs corresponds to a number of BSs which does not increase complexity of the operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS  1300 . 
     In step  1318 , the serving BS  1302  performs a primary filtering by using the cell loading state information of the candidate BSs included in the candidate BS list. That is, when the serving BS  1302  receives the additional access impossibility indication of the corresponding candidate BS from the fronthaul established with each of the candidate BSs or the SON server  1308 , the serving BS  1002  removes the corresponding candidate BS from the candidate BS list. In step  1320 , the serving BS  1302  calculates service quality of each of the remaining candidate BSs, that is, primarily filtered candidate BSs except for the candidate BSs of which the additional access possibility indication is received. For the convenience of description, it is assumed that the primarily filtered candidate BSs are adjacent BS#1  1304  and adjacent BS#2  1306 . Then, the serving BS  1302  calculates service quality of each of adjacent BS#1  1304  and adjacent BS#2  1306  by using BS information pre-acquired through the fronthaul establishment process with each of adjacent BS#1  1304  and adjacent BS#2  1306 . In step  1322 , the serving BS  1302  performs a secondary filtering for identifying whether the service quality calculated for each of the primarily filtered adjacent BSs, that is, adjacent BS#1  1304  and adjacent BS#2  1306  is larger than or equal to a predetermined service quality threshold. In step  1324 , the serving BS  1002  determines the candidate BS having service quality larger than or equal to the service quality threshold, that is, secondarily filtered candidate BSs as a target to receive a member BS negotiation among the primarily filtered candidate BSs. For the convenience of description, for example, it is assumed that adjacent BS#2  1306  is determined as the target to receive the member BS negotiation. Then, in steps  1326   a  and  1326   b , the serving BS  1302  performs the member BS negotiation with adjacent BS#1  1304  and adjacent BS#2  1306 . For example, when the member BS negotiation with adjacent BS#2  1306  is successfully performed, the serving BS  1302  determines to add adjacent BS#2  1306  as a new member BS in step  1328 . In the member BS negotiation, the serving BS  1302  makes, to adjacent BS#2  1306 , a request for a BS capability state required when adjacent BS#2  1306  operates as the member BS within the cooperative communication-based cell of the MS  1300 . For example, the BS capability state includes a number of antennas of the corresponding BS, currently remaining power, available buffer capacity, cell load, and a number of available chains. Further, when the serving BS  1302  receives a response satisfying the required BS capability state, the member BS negotiation is successfully performed. 
     In step  1330 , the serving BS  1302  transmits update information informing that adjacent BS#2  1302  has been added as the new member BS and indication information of adjacent BS#2  1306  to the MS  1300 . The information may be transmitted through an access response to the access request. In step  1332 , the serving BS  1302  updates the new member BS. Meanwhile, although it has been described as an example that the member BS update process corresponds to adding the new cooperative BS in  FIG. 13 , the member BS update process may be expanded to a case where the existing member BS is removed or a case where the serving BS  1302  is determined as the existing or new member BS. 
       FIG. 14  illustrates an example of a schematic configuration of the MS according to an embodiment of the present disclosure. 
     Referring to  FIG. 14 , an MS  1400  includes, for example, a transceiver  1405 , a measurement unit  1410 , a candidate BS list generator  1415 , and a controller  1420 . For the convenience of description, the configuration of the MS  1400  in  FIG. 14  is divided into a plurality of units separated by operations according to an embodiment of the present disclosure. However, the configuration of the MS may be configured by one unit or divided into other types of sub units according to real implementations. 
     An operation of the MS  1400  according to the present disclosure is largely divided into the operation according to the embodiments discussed above with regard to  FIGS. 2-5  and  FIGS. 10-13  and the operation according to the embodiments discussed above with regard to  FIGS. 10-13 . 
     First, in the operation of the MS  1400  according to the embodiments discussed above with regard to  FIGS. 2-5  and  FIGS. 10-13  of the present disclosure, the measurement unit  1410  measures strength of signals received from adjacent BSs included in a scanning set or performs blind scanning on BSs recognized without the aid of the serving BS. 
     The transceiver  1405  receives cell loading state information of the adjacent BSs through a broadcasting channel. 
     Then, the controller  1420  sets a candidate BS determination condition by using at least one of a predetermined signal strength threshold and a cell load threshold and transmits the set candidate BS determination condition to the BS list generator  1415 . The candidate BS list generator  1415  includes the candidate BS list by adjacent BSs which satisfy at least one of a condition in which signal strength is larger than or equal to a signal strength threshold and a condition in which an amount of available resources indicated by the cell loading state information is larger than or equal to a minimum cell load value or an amount of used resources is smaller than a maximum cell load value. In another example, parameters may be used for the candidate BS determination condition when the MS  1400  acquires BS basic setting information, for example, information on a maximum buffer size, a maximum number of antennas, a maximum number of RF chains, and a maximum number of beams. Further, information required for expecting a degree of a service to be received by the MS through the corresponding BS may be also used for the candidate BS determination condition. Then, the controller  1420  controls the transceiver  1405  to transmit the candidate BS list to the serving BS managing the cooperative communication-based cell of the MS  1400 . Since the operation according to the embodiments discussed above with regard to  FIGS. 2-5  and  FIGS. 10-13  of the present disclosure as described above overlap the operation according to  FIGS. 3 and 11 , a detailed description thereof will be omitted. 
     Meanwhile, in the operation of the MS  1400  according to the embodiments discussed above with regard to  FIGS. 6-9  of the present disclosure, when the transceiver  1405  recognizes reception of the candidate BS list transmitted from the serving BS, the controller  1420  controls the measurement unit  1410  to measure signal strength received from each of the candidate BSs included in the candidate BS list. The candidate BS list transmitted from the serving BS includes adjacent BSs having service quality larger than or equal to a service quality threshold among the adjacent BSs having established the fronthaul with the serving BS. Further, the controller  1420  stores cell loading state information of the candidate BSs which the transceiver  1405  receives through the broadcasting channel. In addition, the controller  1420  sets a candidate BS determination condition by using at least one of a predetermined signal strength threshold and a cell load threshold and transmits the set candidate BS determination condition to the BS list generator  1415 . Then, the candidate BS list generator  1415  re-configures the candidate BS list by candidate BSs which satisfy at least one of a condition in which signal strength of each of the candidate BSs included in the candidate BS list is larger than or equal to the signal strength threshold and a condition in which an amount of available resources is larger than or equal to a minimum cell load value or an amount of used resources is smaller than a maximum cell load value. Then, the controller  1420  controls the transceiver  1405  to transmit the re-configured candidate BS list to the serving BS managing the cooperative communication-based cell of the MS  1400 . 
       FIG. 15  illustrates an example of a schematic configuration of the serving BS according to an embodiment of the present disclosure. 
     Referring to  FIG. 15 , a serving BS  1500  includes, for example, a transceiver  1505 , a candidate BS filtering unit  1510 , a member BS determiner  1515 , and a controller  1520 . For the convenience of description, the configuration of the serving BS  1500  in  FIG. 15  is divided into a plurality of units separated by operations according to an embodiment of the present disclosure. However, the configuration of the serving BS may be configured by one unit or divided into other types of sub units according to real implementations. 
     First, when the serving BS  1500  operates according to the embodiments discussed above with regard to  FIGS. 2-5  of the present disclosure, the transceiver  1505  receives a candidate BS list from the MS. The candidate BS list is configured by candidate BSs satisfying a candidate BS determination condition. Since the candidate BS determination condition and the process of generating the candidate BSs overlap the description of  FIG. 3 , a detailed description thereof will be omitted herein. 
     When the controller  1520  recognizes reception of the candidate BS list, the controller  1520  determines a total number of member BSs to configure the cooperative communication-based cell of the MS. The number of member BSs is defined as a total number of cooperative BSs except for the serving BS  1500 . The number of member BSs corresponds to a number of BSs which does not increase complexity of the operation of the cooperative communication-based cell and maximizes capability of throughput of the cooperative communication-based cell and also corresponds to a number of BSs which can be supported by the MS. The controller  1520  determines a service quality threshold and transmits the determined service quality threshold to the candidate BS filtering unit  1510 . 
     The candidate BS filtering unit  1510  calculates service quality by using BS information of the adjacent BS corresponding to the candidate BS among the BS information through the fronthaul establishment process. The candidate BS filtering unit  1510  determines candidate BSs having service quality larger than or equal to the service quality threshold as targets to receive the member BS negotiation. 
     Then, the member BS determiner  1515  performs the transaction negotiation with the targets to receive the member BS negotiation and identifies whether a channel state of the corresponding BS satisfies a BS capability state required for the cooperative communication-based cell of the MS. For example, the BS capability state includes a channel state between the corresponding BS and the serving BS  602  (for example, RSSI, path loss and the like), a number of available antennas of the corresponding BS, currently remaining power, available buffer capacity, current cell load, and a number of available RF chains. The targets to receive the member BS negotiation which satisfy the BS capability state are determined as final member BSs. Then, the controller  1520  controls the transceiver  1505  to transmit information on the final member BSs to the MS. 
     Meanwhile, the operation of the serving BS  1500  according to the embodiments discussed above with regard to  FIGS. 10-13  of the present disclosure is almost similar to the operation of the serving BS according to the embodiments discussed above with regard to  FIGS. 2-5  of the present disclosure. However, the candidate BS filtering unit  1510  first performs the filtering using the cell loading state information prior to the filtering using the serving quality of the candidate BSs. That is, the candidate BS filtering unit  1510  identifies whether the cell loading state information corresponding to the candidate BSs includes an additional access impossibility indication among the cell loading state information acquired through the fronthaul establishment process with the adjacent BSs or communication with the SON server. As a result of the identification, the candidate BSs including the additional access impossibility indication are excluded from the candidate BS list, and the candidate BS filtering unit  1510  performs the filtering using the serving quality of the remaining candidate BSs. 
     Last, in the operation of the serving BS  1500  according to the embodiments discussed above with regard to  FIGS. 6-9  of the present disclosure, the serving BS  1500  does not wait for reception of the candidate BS list but directly generates the candidate BS list unlike the embodiments discussed above with regard to  FIGS. 2-5  and  FIGS. 10-13  of the present disclosure. Specifically, the controller  1520  acquires BS information of the adjacent BSs during the fronthaul establishment process with the adjacent BSs. Then, the candidate BS filtering unit  1510  calculates service quality by using the BS information of the adjacent BSs and selects adjacent BSs having the calculated service quality larger than or equal to a service quality threshold. Further, the candidate BS filtering unit  1510  generates a candidate BS list by the selected adjacent BSs. Then, the controller transmits the candidate BS list to the MS through the transceiver  1505 . 
     Thereafter, when the transceiver  1505  recognizes reception of the re-configured candidate BS list from the MS, the controller  1520  controls the member BS determiner  1515  to determine the candidate BSs included in the re-configured candidate BS list as targets to receive the member BS negotiation. Then, the member BS determiner  1515  performs the transaction negotiation with the targets to receive the member BS negotiation and identifies whether BS capability of the corresponding BS satisfies a BS capability state required for the cooperative communication-based cell of the MS. The targets to receive the member BS negotiation which satisfy the BS capability state are determined as final member BSs. Then, the controller  1520  controls the transceiver  1505  to transmit information on the final member BSs to the MS. 
     Meanwhile, since the configurations of the MS and the serving BS in  FIGS. 14 and 15  are equally applied to the member BS update processes in  FIGS. 5, 9 and 13  and overlap the previous description, a detailed description thereof will be omitted. 
     Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.