Patent Publication Number: US-2023139611-A1

Title: Communication system and method using large intelligent surface

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation application, claiming priority under § 365(c), of an International application No. PCT/KR2022/013323, filed on Sep. 6, 2022, which is based on and claims the benefit of a Korean patent application number 10-2021-0148735, filed on Nov. 2, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     The disclosure relates to communication technology using a large intelligent surface (LIS). 
     2. Description of Related Art 
     Currently, as a new radio (NR) standard that is a 5th generation (5G) data transmission method is completed by 3rd Generation Partnership Project (3GPP) Release 16 and standardization of 3GPP Release 17 is in progress, many studies are being conducted on beyond-5G data transmission technique. One of core beyond-5G techniques is a communication system using a meta-surface. The meta-surface includes a meta material. The largest difference between the meta-surface and a normal surface lies in that it is possible to adjust a reflection and a refraction by adjusting a density of a medium by applying a stimulus to the meta material and by transforming a wavelength form of a signal according to a generalized Snell&#39;s law. 
     A large intelligent surface (LIS) system that is one of systems using the meta-surface allows a data transmission beyond an existing large-capacity antenna system. 
     The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure. 
     SUMMARY 
     To secure a larger frequency bandwidth in 5G communication and 6th generation (6G) communication, communication using a millimeter wave (mmWave) (e.g., 10 to 100 gigahertz (GHz)) frequency or a terahertz (e.g., 0.1 to 10 terahertz (THz)) frequency is being discussed. In this frequency bandwidth, a free space loss (FSL) is very large and thus, it is important to minimize a pathloss by securing a line-of-sight (LOS). 
     Aspects of the disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide a communication system for minimizing a pathloss using a large intelligent surface (LIS). 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     In accordance with an aspect of the disclosure, a communication method using an LIS is provided. The communication method includes transmitting, by a terminal, preamble signals each with a different transmission time and transmission direction, receiving, by an LIS server, at least one preamble signal among the preamble signals through an LIS through which an incident radio wave is received and reflected and determining a reference angle of incidence for the at least one preamble signal, receiving, by a base station, the preamble signals that are delivered through a multipath from the terminal, transmitting, by the base station, identification information of a preamble signal having the largest reception power among the received preamble signals to the LIS server, and when the at least one preamble signal includes a preamble signal corresponding to the identification information received from the base station, controlling, by the LIS server, the LIS such that an angle of reflection at which a data service signal transmitted from the base station is reflected by the LIS corresponds to the reference angle of incidence determined for the preamble signal of the identification information. 
     In accordance with another aspect of the disclosure, a communication system using an LIS is provided. The communication system includes a terminal, a base station, an LIS including a meta-surface and in which an angle of reflection of an incident radio wave is adjusted according to an electrical stimulation, and an LIS server configured to control the LIS. The terminal may be configured to transmit preamble signals each with a different transmission time and transmission direction, the LIS server may be configured to receive at least one preamble signal among the preamble signals through the LIS and determine a reference angle of incidence for the at least one preamble signal, the base station may be configured to receive the preamble signals that are delivered through a multipath from the terminal, and transmit identification information of a preamble signal having the largest reception power among the received preamble signals to the LIS server, and the LIS server may be configured to, when the at least one preamble signal includes a preamble signal corresponding to the identification information received from the base station, control the LIS such that an angle of reflection at which a data service signal transmitted from the base station is reflected by the LIS corresponds to the reference angle of incidence determined for the preamble signal of the identification information. 
     A communication system using an LIS according to an example embodiment may determine a terminal that requests a data service and a location of the corresponding terminal, and may control the LIS such that a signal transmitted from a base station may be reflected by the LIS and delivered to the terminal, thereby minimizing a pathloss of the signal transmitted from the base station. 
     Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a block diagram illustrating an example terminal in a network environment according to an embodiment of the disclosure; 
         FIG.  2    illustrates a communication system using a large intelligent surface (LIS) according to an embodiment of the disclosure; 
         FIG.  3    illustrates an LIS included in a communication system according to an embodiment of the disclosure; 
         FIG.  4    is a flowchart illustrating a communication method using an LIS according to an embodiment of the disclosure; 
         FIG.  5 A  illustrates a location operation of a communication system according to an embodiment of the disclosure; 
         FIG.  5 B  illustrates a positioning operation of a communication system according to an embodiment of the disclosure; 
         FIG.  6    illustrates a detailed positioning operation of a communication system according to an embodiment of the disclosure; 
         FIG.  7 A  illustrates a location method for a plurality of terminals of a communication system according to an embodiment of the disclosure; 
         FIG.  7 B  illustrates a positioning method for a plurality of terminals of a communication system according to an embodiment of the disclosure; 
         FIG.  8    is a flowchart illustrating a communication method using an LIS according to an embodiment of the disclosure; and 
         FIG.  9    is a flowchart illustrating a communication method using an LIS performed by a base station, an LIS device, and a terminal in a communication system according to an embodiment of the disclosure. 
     
    
    
     Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
     DETAILED DESCRIPTION 
     The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents. 
     It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
       FIG.  1    is a block diagram illustrating an electronic device in a network environment according to an embodiment of the disclosure. 
     Referring to  FIG.  1   , an electronic device  101  in a network environment  100  may communicate with an external electronic device  102  via a first network  198  (e.g., a short-range wireless communication network), or communicate with at least one of an external electronic device  104  or a server  108  via a second network  199  (e.g., a long-range wireless communication network). According to an example embodiment, the electronic device  101  may communicate with the external electronic device  104  via the server  108 . According to an example embodiment, the electronic device  101  may include any one or any combination of a processor  120 , a memory  130 , an input module  150 , a sound output module  155 , a display module  160 , an audio module  170 , and a sensor module  176 , an interface  177 , a connecting terminal  178 , a haptic module  179 , a camera module  180 , a power management module  188 , a battery  189 , a communication module  190 , a subscriber identification module (SIM)  196 , and an antenna module  197 . In some example embodiments, at least one (e.g., the connecting terminal  178 ) of the above components may be omitted from the electronic device  101 , or one or more other components may be added in the electronic device  101 . In some example embodiments, some (e.g., the sensor module  176 , the camera module  180 , or the antenna module  197 ) of the components may be integrated as a single component (e.g., the display module  160 ). 
     The processor  120  may execute, for example, software (e.g., a program  140 ) to control at least one other component (e.g., a hardware or software component) of the electronic device  101  connected to the processor  120 , and may perform various data processing or computation. According to an example embodiment, as at least a part of data processing or computation, the processor  120  may store a command or data received from another components (e.g., the sensor module  176  or the communication module  190 ) in a volatile memory  132 , process the command or the data stored in the volatile memory  132 , and store resulting data in a non-volatile memory  134 . According to an example embodiment, the processor  120  may include a main processor  121  (e.g., a central processing unit (CPU) or an application processor (AP)) or an auxiliary processor  123  (e.g., a graphics processing unit (GPU), a neural processing unit (NPU), an image signal processor (ISP), a sensor hub processor, or a communication processor (CP)) that is operable independently of, or in conjunction with the main processor  121 . For example, when the electronic device  101  includes the main processor  121  and the auxiliary processor  123 , the auxiliary processor  123  may be adapted to consume less power than the main processor  121  or to be specific to a specified function. The auxiliary processor  123  may be implemented separately from the main processor  121  or as a part of the main processor  121 . 
     The auxiliary processor  123  may control at least some of functions or states related to at least one (e.g., the display module  160 , the sensor module  176 , or the communication module  190 ) of the components of the electronic device  101 , instead of the main processor  121  while the main processor  121  is in an inactive (e.g., sleep) state or along with the main processor  121  while the main processor  121  is an active state (e.g., executing an application). According to an example embodiment, the auxiliary processor  123  (e.g., an ISP or a CP) may be implemented as a portion of another component (e.g., the camera module  180  or the communication module  190 ) that is functionally related to the auxiliary processor  123 . According to an example embodiment, the auxiliary processor  123  (e.g., an NPU) may include a hardware structure specified for artificial intelligence model processing. An artificial intelligence model may be generated by machine learning. Such learning may be performed by, for example, the electronic device  101  in which artificial intelligence is performed, or performed via a separate server (e.g., the server  108 ). Learning algorithms may include, but are not limited to, for example, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning. The artificial intelligence model may include a plurality of artificial neural network layers. An artificial neural network may include, for example, a deep neural network (DNN), a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted Boltzmann machine (RBM), a deep belief network (DBN), and a bidirectional recurrent deep neural network (BRDNN), a deep Q-network, or a combination of two or more thereof, but is not limited thereto. The artificial intelligence model may additionally or alternatively, include a software structure other than the hardware structure. 
     The memory  130  may store various data used by at least one component (e.g., the processor  120  or the sensor module  176 ) of the electronic device  101 . The various data may include, for example, software (e.g., the program  140 ) and input data or output data for a command related thereto. The memory  130  may include the volatile memory  132  or the non-volatile memory  134 . 
     The program  140  may be stored as software in the memory  130 , and may include, for example, an operating system (OS)  142 , middleware  144 , or an application  146 . 
     The input module  150  may receive a command or data to be used by another component (e.g., the processor  120 ) of the electronic device  101 , from the outside (e.g., a user) of the electronic device  101 . The input module  150  may include, for example, a microphone, a mouse, a keyboard, a key (e.g., a button), or a digital pen (e.g., a stylus pen). 
     The sound output module  155  may output a sound signal to the outside of the electronic device  101 . The sound output module  155  may include, for example, a speaker or a receiver. The speaker may be used for general purposes, such as playing multimedia or playing record. The receiver may be used to receive an incoming call. According to an example embodiment, the receiver may be implemented separately from the speaker or as a part of the speaker. 
     The display module  160  may visually provide information to the outside (e.g., a user) of the electronic device  101  (e.g., a user). The display module  160  may include, for example, a control circuit for controlling a display, a hologram device, or a projector and control circuitry to control a corresponding one of the display, the hologram device, and the projector. According to an example embodiment, the display module  160  may include a touch sensor adapted to sense a touch, or a pressure sensor adapted to measure an intensity of a force incurred by the touch. 
     The audio module  170  may convert a sound into an electric signal or vice versa. According to an example embodiment, the audio module  170  may obtain the sound via the input module  150  or output the sound via the sound output module  155  or an external electronic device (e.g., the external electronic device  102  such as a speaker or a headphone) directly or wirelessly connected to the electronic device  101 . 
     The sensor module  176  may detect an operational state (e.g., power or temperature) of the electronic device  101  or an environmental state (e.g., a state of a user) external to the electronic device  101 , and generate an electric signal or data value corresponding to the detected state. According to an example embodiment, the sensor module  176  may include, for example, a gesture sensor, a gyro sensor, an atmospheric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illuminance sensor. 
     The interface  177  may support one or more specified protocols to be used for the electronic device  101  to be coupled with the external electronic device (e.g., the external electronic device  102 ) directly (e.g., by wire) or wirelessly. According to an example embodiment, the interface  177  may include, for example, a high-definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface. 
     The connecting terminal  178  may include a connector via which the electronic device  101  may be physically connected to an external electronic device (e.g., the external electronic device  102 ). According to an example embodiment, the connecting terminal  178  may include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., a headphone connector). 
     The haptic module  179  may convert an electric signal into a mechanical stimulus (e.g., a vibration or a movement) or an electrical stimulus which may be recognized by a user via his or her tactile sensation or kinesthetic sensation. According to an example embodiment, the haptic module  179  may include, for example, a motor, a piezoelectric element, or an electric stimulator. 
     The camera module  180  may capture a still image and moving images. According to an example embodiment, the camera module  180  may include one or more lenses, image sensors, image signal processors, or flashes. 
     The power management module  188  may manage power supplied to the electronic device  101 . According to an example embodiment, the power management module  188  may be implemented as, for example, at least a part of a power management integrated circuit (PMIC). 
     The battery  189  may supply power to at least one component of the electronic device  101 . According to an example embodiment, the battery  189  may include, for example, a primary cell which is not rechargeable, a secondary cell which is rechargeable, or a fuel cell. 
     The communication module  190  may support establishing a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device  101  and the external electronic device (e.g., the external electronic device  102 , the external electronic device  104 , or the server  108 ) and performing communication via the established communication channel. The communication module  190  may include one or more communication processors that are operable independently of the processor  120  (e.g., an AP) and that support a direct (e.g., wired) communication or a wireless communication. According to an example embodiment, the communication module  190  may include a wireless communication module  192  (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module  194  (e.g., a local area network (LAN) communication module, or a power line communication (PLC) module). A corresponding one of these communication modules may communicate with the external electronic device  104  via the first network  198  (e.g., a short-range communication network, such as Bluetooth™ wireless-fidelity (Wi-Fi) direct, or infrared data association (IrDA)) or the second network  199  (e.g., a long-range communication network, such as a legacy cellular network, a 5G network, a next-generation communication network, the Internet, or a computer network (e.g., an LAN or a wide area network (WAN))). These various types of communication modules may be implemented as a single component (e.g., a single chip), or may be implemented as multi components (e.g., multi chips) separate from each other. The wireless communication module  192  may identify and authenticate the electronic device  101  in a communication network, such as the first network  198  or the second network  199 , using subscriber information (e.g., international mobile subscriber identity (IMSI)) stored in the SIM  196 . 
     The wireless communication module  192  may support a 5G network after a 4th generation (4G) network, and a next-generation communication technology, e.g., new radio (NR) access technology. The NR access technology may support enhanced mobile broadband (eMBB), massive machine type communications (mMTC), or ultra-reliable and low-latency communications (URLLC). The wireless communication module  192  may support a high-frequency band (e.g., an mmWave band) to achieve, e.g., a high data transmission rate. The wireless communication module  192  may support various technologies for securing performance on a high-frequency band, such as, e.g., beamforming, massive multiple-input and multiple-output (MIMO), full dimensional MIMO (FD-MIMO), an array antenna, analog beam-forming, or a large scale antenna. The wireless communication module  192  may support various requirements specified in the electronic device  101 , an external electronic device (e.g., the external electronic device  104 ), or a network system (e.g., the second network  199 ). According to an example embodiment, the wireless communication module  192  may support a peak data rate (e.g., 20 Gbps or more) for implementing eMBB, loss coverage (e.g., 164 dB or less) for implementing mMTC, or U-plane latency (e.g., 0.5 ms or less for each of downlink (DL) and uplink (UL), or a round trip of 1 ms or less) for implementing URLLC. 
     The antenna module  197  may transmit or receive a signal or power to or from the outside (e.g., the external electronic device) of the electronic device  101 . According to an example embodiment, the antenna module  197  may include a slit antenna, and/or an antenna including a radiating element including a conductive material or a conductive pattern formed in or on a substrate (e.g., a printed circuit board (PCB)). According to an example embodiment, the antenna module  197  may include a plurality of antennas (e.g., array antennas). In such a case, at least one antenna appropriate for a communication scheme used in a communication network, such as the first network  198  or the second network  199 , may be selected by, for example, the communication module  190  from the plurality of antennas. The signal or the power may be transmitted or received between the communication module  190  and the external electronic device via the at least one selected antenna. According to an example embodiment, another component (e.g., a radio frequency integrated circuit (RFIC)) other than the radiating element may be additionally formed as a part of the antenna module  197 . 
     According to various example embodiments, the antenna module  197  may form an mmWave antenna module. According to an example embodiment, the mmWave antenna module may include a PCB, an RFIC disposed on a first surface (e.g., a bottom surface) of the PCB or adjacent to the first surface and capable of supporting a designated a high-frequency band (e.g., the mmWave band), and a plurality of antennas (e.g., array antennas) disposed on a second surface (e.g., a top or a side surface) of the PCB, or adjacent to the second surface and capable of transmitting or receiving signals in the designated high-frequency band. 
     At least some of the above-described components may be coupled mutually and communicate signals (e.g., commands or data) therebetween via an inter-peripheral communication scheme (e.g., a bus, general purpose input and output (GPIO), serial peripheral interface (SPI), or mobile industry processor interface (MIPI)). 
     According to an example embodiment, commands or data may be transmitted or received between the electronic device  101  and the external electronic device  104  via the server  108  coupled with the second network  199 . Each of the external electronic devices  102  and  104  may be a device of the same type as or a different type from the electronic device  101 . According to an example embodiment, all or some of operations to be executed by the electronic device  101  may be executed at one or more of the external electronic devices  102  and  104  and the server  108 . For example, if the electronic device  101  needs to perform a function or a service automatically, or in response to a request from a user or another device, the electronic device  101 , instead of, or in addition to, executing the function or the service, may request one or more external electronic devices to perform at least part of the function or the service. The one or more external electronic devices receiving the request may perform the at least part of the function or the service requested, or an additional function or an additional service related to the request, and may transfer an outcome of the performing to the electronic device  101 . The electronic device  101  may provide the outcome, with or without further processing of the outcome, as at least part of a reply to the request. To that end, a cloud computing, distributed computing, mobile edge computing (MEC), or client-server computing technology may be used, for example. The electronic device  101  may provide ultra low-latency services using, e.g., distributed computing or mobile edge computing. In an example embodiment, the external electronic device  104  may include an Internet-of-things (IoT) device. The server  108  may be an intelligent server using machine learning and/or a neural network. According to an example embodiment, the external electronic device  104  or the server  108  may be included in the second network  199 . The electronic device  101  may be applied to intelligent services (e.g., smart home, smart city, smart car, or healthcare) based on 5G communication technology or IoT-related technology. 
       FIG.  2    illustrates a communication system using a large intelligent surface (LIS) according to an embodiment of the disclosure. 
     Referring to  FIG.  2   , a wireless communication system  200  (hereinafter, a communication system) using an LIS according to an example embodiment may include a terminal  225  (e.g., the electronic device  101  of  FIG.  1   ) configured to request a data service, a base station (BS)  230  configured to provide the data service to the terminal  225 , an LIS by which a data service signal provided from the base station  230  is reflected, and an LIS server  220  configured to control the LIS. The data service signal may refer to at least one of a downlink data transmission signal and an uplink data transmission signal. A representation of the LIS may be replaced by a representation of a reconfigurable intelligent surface (RIS) or an intelligent reflecting surface (IRS). 
       FIG.  2    illustrates buildings  205  and  210  each with an LIS attached (or mounted or installed) to an exterior wall of each building. However, it is provided as an example only and the LIS may be designed in various forms other than a form attached to a building. 
     Although  FIG.  2    illustrates that a single LIS server  220  controls all of LISs, for example, LIS1 and LIS2, attached to the buildings  205  and  210 , it is provided as an example only. An individual LIS server may be present to control the LIS attached to each corresponding building  205  or building  210 . 
     In an example embodiment, the wireless communication system  200  may use a millimeter wave (mmWave) (e.g., 10 to 100 gigahertz (GHz)) frequency or a terahertz (e.g., 0.1 to 10 terahertz (THz)) frequency to secure a larger frequency bandwidth. Also, the wireless communication system  200  may employ beamforming technology using a multi-antenna to improve the power efficiency of wireless communication. A transmission side of transmitting a signal may improve directivity by concentrating a signal transmitted from each antenna in a specific direction (i.e., space) using a plurality of antennas (e.g., an array antenna) and a reception side of receiving the corresponding signal may increase sensitivity of a received signal that comes in the corresponding specific direction by concentrating reception of a radio wave in the specific direction and may block an interference signal by excluding a signal that comes in another direction. 
     In an example embodiment, an LIS may include a plurality of meta-surfaces and a beamforming function may be performed using the plurality of meta-surfaces. A radio wave incident to the LIS may be received and reflected by the plurality of meta-surfaces. The plurality of meta-surfaces included in the LIS may be controlled by the LIS server  220 . For example, density of the plurality of meta-surfaces may be adjusted by a stimulation (e.g., an electrical stimulation) generated from the LIS server  220 . The LIS server  220  may adjust a reflection and a refraction by transforming a wavelength form of an incident radio wave according to a generalized Snell&#39;s law by adjusting the density of the plurality of meta-surfaces. The LIS server  220  may concentrate a radio wave reception direction or may concentrate a reflected radio wave by appropriately controlling the density of the plurality of meta-surfaces included in the LIS. 
     Since a free space loss (FSL) is very large and a number of multipaths significantly decreases in a very high frequency bandwidth, such as an mmWave frequency or a THz frequency, it may be important to minimize a pathloss by securing a line-of-sight (LOS). 
     In a very high frequency communication environment, the LIS may improve communication performance of a very high frequency bandwidth by forming an additional multipath between the base station  230  and the terminal  225 . 
     For example, referring to  FIG.  2   , a data service signal transmitted from the base station  230  may not be directly delivered to the terminal  225  due to an obstacle  240 . The data service signal transmitted from the base station  230  may be reflected by the LIS attached to the exterior wall of the building  205  or building  210  and then delivered to the terminal  225 , instead of being directly delivered to the terminal  225 . 
     In an example embodiment, the terminal  225  may transmit preamble signals to receive a data service. The preamble signals may be transmitted through beams each with a different transmission time and transmission direction. The preamble signals may be identified based on identification information for identifying the preamble signals. Identification information of a preamble signal may include one of a beam index and an identification ID of the corresponding preamble signal. In an example embodiment, each of the preamble signals may include a unique identification ID of each corresponding preamble signal. In another example embodiment, each of preamble signals transmitted through beams may be identified using a beam index for identifying a corresponding beam. In an example embodiment, preamble signals may include preamble information. 
     In an example embodiment, the LIS server  220  may receive at least one preamble signal among preamble signals transmitted from the terminal  225  through the LIS attached to the exterior wall of the building  205  or building  210 , and may determine an angle of incidence at which each preamble signal is received. A radio wave reception direction of the LIS may be set by the LIS server  220  and an angle of incidence at which a corresponding preamble signal is received may be determined based on the radio wave reception direction of the LIS. 
     For example, the LIS server  220  may receive a first preamble signal transmitted from the terminal  225  through the LIS, for example, LIS1, attached to the building  205  and may receive a second preamble signal transmitted from the terminal  225  through the LIS, for example, LIS2, attached to the building  210 . The LIS server  220  may determine an angle of incidence at which the first preamble signal is received and an angle of incidence at which the second preamble signal is received. 
     In an example embodiment, the LIS server  220  may match and store preamble information included in a preamble signal being received, identification information of the corresponding preamble signal (e.g., an identification ID or a beam index of the preamble signal), and an angle of incidence at which the preamble signal is received. 
     Preamble signals transmitted from the terminal  225  may be reflected by the LIS. The preamble signals transmitted from the terminal  225  may be delivered to the base station  230  through a multipath. The base station  230  may receive preamble signals that include the preamble signal reflected by the LIS and are delivered through the multipath. The base station  230  may extract preamble information from the received preamble signals and may determine the terminal  225  to which the data service is to be provided. 
     In an example embodiment, the base station  230  may determine a preamble signal having the largest reception power among the received preamble signals. That the reception power is largest may represent that a signal is delivered with the best efficiency among a plurality of radio wave delivery paths. 
     In an example embodiment, the base station  230  may transmit identification information of the determined preamble signal to the LIS server  220 . When a preamble signal corresponding to the identification information received from the base station  230  is present in at least one preamble signal received through the LIS, the LIS server  220  may control the LIS such that an angle of reflection at which a data service signal transmitted from the base station  230  is reflected by the LIS corresponds to an angle of incidence at which the preamble signal of the corresponding identification information is incident. 
     Since the LIS server  220  controls the angle of reflection of the LIS, the data service signal transmitted from the base station  230  may be further better delivered to the terminal  225 . 
     For example, in  FIG.  2   , the base station  230  may receive the first preamble signal reflected by the LIS attached to the building  205  and the second preamble signal reflected by the LIS attached to the building  210 . Here, when reception power of the first preamble signal between two preamble signals is larger, the base station  230  may deliver an identification ID of the first preamble signal or a beam index of the first preamble signal to the LIS server  220  as identification information of the first preamble signal. The LIS server  220  may control the LIS (e.g., the LIS attached to the building  205 ) such that the angle of reflection at which the data service signal transmitted from the base station  230  is reflected by the LIS corresponds to the angle of incidence of the first preamble signal based on an angle of incidence of the first preamble signal corresponding to the identification information received from the base station  230  between the first and second preamble signals received from the terminal  225 . 
     The base station  230  may transmit the data service signal in various directions and, when the data service signal is reflected by the LIS attached to the building  205 , the data service signal with good signal quality may be delivered to the terminal  225 . 
     Hereinafter, an LIS is described with reference to  FIG.  3   . 
       FIG.  3    illustrates an LIS included in a communication system according to an embodiment of the disclosure. 
     Referring to  FIG.  3   , a plurality of LISs  310 ,  315 ,  320 , and  325 , a plurality of meta-surfaces (e.g., a meta-surface  365 ) included in each of the plurality of LISs  310 ,  315 ,  320 , and  325 , an LIS controller  305  configured to control the plurality of LISs  310 ,  315 ,  320 , and  325 , the base station (BS)  230 , and terminals, for example, a first terminal (MS1)  335  and a second terminal (MS2)  340 , configured to receive a signal transmitted from the base station  230  and reflected by the LISs  315  and  320 . In an example embodiment, the LIS controller  305  may be included in an LIS server (e.g., the LIS server  220  of  FIG.  2   ). 
     The plurality of LISs  310 ,  315 ,  320 , and  325  of  FIG.  3    may be attached to an exterior wall of a single building (e.g., the building  205  of  FIG.  2   ). Although  FIG.  3    illustrates four LISs, it is provided as an example for concise description. If necessary, the wireless communication system  200  may include a larger number of LISs. The plurality of LISs  310 ,  315 ,  320 , and  325  may be arranged in a two-dimensional (2D) array form. 
     A data service signal transmitted from the base station  230  to provide a data service may be reflected by a meta-surface included in the LISs  310 ,  315 ,  320 ,  325  and then delivered to the corresponding terminal. For example, a data service signal for the first terminal  335  may be reflected by a meta-surface of the LIS  315  and delivered to the first terminal  335  at an angle of incidence  345  and an angle of reflection  350 , and a data service signal for the second terminal  340  may be reflected by a meta-surface of the LIS  320  and delivered to the second terminal  340  at an angle of incidence  355  and an angle of reflection  360 . 
     The LIS controller  305  may rearrange scattering particles on the meta-surface by applying an electrical stimulation on each of the LISs  310 ,  315 ,  320 , and  325  and may control an angle of reflection (e.g., the angle of reflection  350 ,  360 ) at which a radio wave is reflected on the meta-surface. 
     Hereinafter, a communication method using an LIS is described with reference to  FIG.  4   . 
       FIG.  4    is a flowchart illustrating a communication method using an LIS according to an embodiment of the disclosure. 
     Referring to  FIG.  4   , the communication method using the LIS according to an example embodiment may include a location operation (operation  405 ) in which an LIS server (e.g., the LIS server  220  of  FIG.  2   ) finds an LIS with best reception quality of a preamble signal transmitted from a terminal (e.g., the terminal  225  of  FIG.  2   ) among a plurality of LISs (e.g., the plurality of LISs  310 ,  315 ,  320 , and  325  of  FIG.  3   ) in an initial access stage and a positioning operation (operation  410 ) in which the LIS server controls an angle of reflection at which a data service signal transmitted from a base station (e.g., the base station  230  of  FIG.  2   ) is reflected by each of the plurality of LISs. 
     In operation  405 , the LIS server may set radio wave reception directions of the plurality of LISs such that each of the plurality of LISs may receive a radio wave in a different direction. The terminal may transmit preamble signals to receive a data service from the base station and the LIS server may receive and reflect at least one preamble signal among preamble signals transmitted from the terminal through the plurality of LISs. Hereinafter, description is made for concise description based on an example of using a first preamble signal that is one of at least one preamble signal received through the plurality of LISs. 
     The LIS server may tag and store preamble information of the first preamble signal received through each of the plurality of LISs, identification information of the first preamble signal, and reception information of each of the plurality of LISs. Identification information of a preamble signal may include one of an identification ID and a beam ID of the preamble signal. In an example embodiment, the identification ID of the preamble signal refers to a unique ID of the preamble signal and may be included in each preamble signal. In another example embodiment, the preamble signals may be identified using a beam index for identifying a beam used to deliver each preamble signal, without including a separate identification ID. 
     In an example embodiment, reception information of each of the plurality of LISs may include information on an angle of incidence corresponding to a radio wave reception direction of each LIS and delay time information and reception power information of the first preamble signal received through each LIS. 
     The LIS server may compare reception power of the first preamble signal received through each of the plurality of LISs, may determine an LIS corresponding to the largest reception power of the first preamble signal as a reference LIS for the first preamble signal, and may determine an angle of incidence of the reference LIS as a reference angle of incidence for the first preamble signal. 
     In operation  410 , the LIS server may determine the angle of reflection at which the data service signal transmitted from the base station is reflected by each of the plurality of LISs based on the reference angle of incidence determined in operation  405 . 
     For example, the base station may receive preamble signals delivered through a multipath from the terminal and may transmit identification information of the first preamble signal having the largest reception power among the received preamble signals to the LIS server. The LIS server may receive the identification information of the first preamble signal from the base station. 
     The LIS server may determine the first preamble signal as the preamble signal corresponding to the identification information received from the base station, among the one or more preamble signals received by the LIS server. The LIS server may control the plurality of LISs such that the angle of reflection at which the data service signal transmitted from the base station is reflected by each of the plurality of LISs corresponds to the reference angle of incidence determined in operation  405  for the first preamble signal, based on the reference angle of incidence of the first preamble signal. 
     In an example embodiment, when a distance between each of the plurality of LISs and the terminal is distant, the LIS server may control an angle of reflection of each of the plurality of LISs to correspond to the reference angle of incidence. When the distance is close, the LIS server may correct the angle of reflection of each of the plurality of LISs based on the reference angle of incidence and may control the reflected data service signal to direct the terminal. 
     Hereinafter, operations  405  and  410  are further description with reference to  FIGS.  5 A and  5 B . 
       FIG.  5 A  illustrates a location operation of a communication system according to an embodiment of the disclosure. 
       FIG.  5 B  illustrates a positioning operation of a communication system according to an embodiment of the disclosure. 
     Referring to  FIG.  5 A , a plurality of LISs  310 ,  315 ,  320 , and  325 , a terminal  225  configured to transmit a first preamble signal, an LIS receiver  510  configured to receive an analog signal through the plurality of LISs  310 ,  315 ,  320 , and  325  and to convert the analog signal to a digital signal, and the LIS controller  305  are illustrated. Here, the LIS receiver  510  and the LIS controller  305  may be included in the LIS server (e.g., the LIS server  220  of  FIG.  2   ). 
     Referring to  FIG.  5 A , the plurality of LISs  310 ,  315 ,  320 , and  325  may be controlled by the LIS controller  305  and may be set to receive a radio wave in different directions  535 ,  540 ,  545 , and  550 , respectively. However, it is provided as an example only. In another example embodiment, at least some of the plurality of LISs  310 ,  315 ,  320 , and  325  may be set to receive a radio wave in the same direction. 
     The terminal  225  may be beamformed in a specific direction through a multi-antenna of the terminal  225  and may transmit the first preamble signal. The terminal  225  may be beamformed in various directions and may transmit preamble signals. Here, the first preamble signal may be one of the preamble signals transmitted from the terminal  225 . 
     Each of the plurality of LISs  310 ,  315 ,  320 , and  325  may receive at least one preamble signal among the preamble signals transmitted from the terminal  225 . For example, each of the plurality of LISs  310 ,  315 ,  320 , and  325  may receive the first preamble signal transmitted from the terminal  225 . Although the following description is made for concise description based on an example of using the first preamble signal, an operation performed for the first preamble signal may be performed alike on at least one preamble signal received through the plurality of LISs  310 ,  315 ,  320 , and  325 . 
     The first preamble signal received through each of the plurality of LISs  310 ,  315 ,  320 , and  325  may be delivered to the LIS controller  305  through the LIS receiver  510 . The LIS receiver  510  may demodulate the first preamble signal received through each of the plurality of LISs  310 ,  315 ,  320 ,  325  and may convert the same to a digital signal. The LIS controller  305  may receive, from the LIS receiver  510 , and process the first preamble signal converted to the digital signal. 
     In an example embodiment, the LIS controller  305  may tag and store preamble information included in the first preamble signal received through each of the LISs  310 ,  315 ,  320 , and  325  and identification information of the first preamble signal for each of the LISs  310 ,  315 ,  320 , and  325 , together with information on an angle of incidence corresponding to each of the radio wave reception directions  535 ,  540 ,  545 , and  550  of the respective LISs  310 ,  315 ,  320 , and  325 , and delay time information and reception power information of the first preamble signal received through each of the LISs  310 ,  315 ,  320 , and  325 . 
     For example, the LIS controller  305  may tag preamble information and identification information included in the first preamble signal received through the LIS  325 , and information on the angle of incidence corresponding to the radio wave reception direction  550  of the LIS  325 , and delay time information and reception power information of the first preamble signal received through the LIS  325  as information on the LIS  325 , and may store the same in the LIS server  220 . The preamble information included in the first preamble signal may include identification information of the terminal  225  that requests a data service. 
     All of the plurality of LISs  310 ,  315 ,  320 , and  325  may receive the first preamble signal, but may differ from each other in terms of reception power. The LIS  325  of which the radio wave reception direction is directed toward the terminal  225  may receive the first preamble signal with relatively high reception power and the other LISs  310 ,  315  and  320  may receive the first preamble signal with reception power lower than that of the LIS  325  or may fail in receiving the first preamble signal. For the LIS  310  that fails in receiving the first preamble signal, there is no reception information of the LIS  310  on the first preamble signal. Therefore, the reception information of the LIS  310  on the first preamble signal may not be stored in the LIS server  220 . 
     The LIS server  220  may compare the reception power of the first preamble signal received through each of the plurality of LISs  310 ,  315 ,  320 , and  325 , may determine the LIS  325  having the largest reception power of the first preamble signal as a reference LIS for the first preamble signal, and may determine an angle of incidence corresponding to the radio wave reception direction  550  of the LIS  325  as a reference angle of incidence for the first preamble signal. 
     Referring to  FIG.  5 B , the LIS server (e.g., the LIS server  220  of  FIG.  2   ) may control an angle of reflection at which a data service signal transmitted from the base station  230  to a corresponding terminal  225  is reflected by each of the plurality of LISs  310 ,  315 ,  320 , and  325  based on the reference angle of incidence determined in  FIG.  5 A . 
     Referring to  FIG.  5 B , reflection directions  555 ,  560 ,  565 , and  570  in which the angle of reflection at which the data service signal transmitted from the base station  230  is reflected by the plurality of LISs  310 ,  315 ,  320 , and  325  are controlled based on the reference angle of incidence determined in  FIG.  5 A . 
     In an example embodiment, the LIS controller  305  may receive identification information of the first preamble signal from the base station  230 . The LIS controller  305  and the base station  230  may be connected in wired or wireless manner. 
     The LIS controller  305  may control the plurality of LISs  310 ,  315 ,  320 , and  325  such that the angle of reflection at which the data service signal transmitted from the base station  230  is reflected by each of the plurality of LISs  310 ,  315 ,  320 , and  325  corresponds to the reference angle of incidence in  FIG.  5 A  for the first preamble signal, based on the reference angle of incidence of the first preamble signal corresponding to the received preamble identification information. 
     In an example embodiment, when a distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is distant, the LIS controller  305  may control the angle of reflection of each of the plurality of LISs  310 ,  315 ,  320 , and  325  to be the same. When the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is close, the LIS controller  305  may correct the angle of reflection of each of the plurality of LISs  310 ,  315 ,  320 , and  325 , and control the reflected data service signal to be directed toward the terminal  225 . 
     For example, in the example of  FIG.  5 B , the LIS controller  305  may determine that the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is close and may correct the angle of reflection of each of the LISs  310 ,  315 , and  320  and control the LISs  310 ,  315 , and  320  such that the data service signal transmitted from the base station  230  may be reflected in the reflection directions  555 ,  560 , and  565  in which the terminal  225  is present. 
     When the LIS controller  305  determines that the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is distant, the LIS controller  305  may control reflection directions of the plurality of LISs  310 ,  315 ,  320 , and  325  to be the same as the reflection direction  570 . 
     In an example embodiment, whether the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is close may be determined based on reception power of the first preamble signal of each of the LISs  310 ,  315 ,  320 , and  325  stored in the LIS server  220 . For example, the LIS controller  305  may determine the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  based on the largest reception power among reception powers of the first preamble signal of the terminal  225  received through each of the plurality of LISs  310 ,  315 ,  320 , and  325 . For example, the LIS controller  305  may determine the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  based on the reception power of the first preamble signal received through the reference LIS, for example, the LIS  325 , of the terminal  225 . 
     When the determined distance is greater than or equal to a threshold, the LIS controller  305  may determine that the distance is distant. When the determined distance is less than the threshold, the LIS controller  305  may determine that the distance is close. 
     Hereinafter, a method of correcting the angle of reflection of each of the LISs  310 ,  315 ,  320 , and  325  when the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is close is described with reference to  FIG.  6   . 
       FIG.  6    illustrates a detailed positioning operation of a communication system according to an embodiment of the disclosure. 
     Referring to  FIG.  6   , a model in a three-dimensional (3D) planar form between a plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is illustrated. The plurality of LISs  310 ,  315 ,  320 , and  325  may be arranged in a two-dimensional (2D) array form on an x-y plane with a horizontal interval of d x  on the x-axis and a vertical interval of d y  on the y-axis. 
     In the example of  FIG.  6   , the LIS server  220  may perform operation  405  corresponding to the location operation of  FIG.  4    and may determine the LIS  325  as a reference LIS for the first preamble signal. The LIS server  220  may perform operation  410  corresponding to the positioning operation of  FIG.  4    and may determine that a distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is close. 
     When it is determined that the distance between each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the terminal  225  is close, the angle of reflection of each of the plurality of LISs  310 ,  315 , and  320  excluding the reference LIS may need to be corrected to correspond to the reflection directions  555 ,  560 , and  565  based on the reference angle of incidence for the first preamble signal determined in operation  405  of  FIG.  4    such that a radio wave incident to each of the plurality of LISs  310 ,  315 ,  320 , and  325  is reflected and delivered to the terminal  225 . 
     In an example embodiment, the angle of reflection of each of the plurality of LISs  310 ,  315 , and  320  may be corrected based on a distance between the plurality of LISs  310 ,  315 ,  320 , and  325  and the reference angle of incidence for the first preamble signal. 
     Referring to  FIG.  6   , angles of incidence of a radio wave incident from a terminal  225  to the reference LIS, for example, the LIS  325  for the first preamble signal are referred to as θ xz  and θ xy , respectively, on a plane on which the terminal  225  is projected on the x-z plane and a plane on which the terminal  225  is projected on the y-z plane. A distance perpendicular to the terminal  225  and the x-axis on the x-z plane is l xz , and a distance perpendicular to the terminal  225  and the y-axis on the y-z plane is l yz . 
     With the assumption that an angle of reflection from the LIS  315  on the x-z plane to be corrected to the terminal  225  is θ′ xz  and an angle of reflection from the LIS  320  on the y-z plane to the terminal  225  is θ′ yz , the LIS server  220  may perform a calculation according to a trigonometric method as follows. 
     
       
         
           
             
               
                 
                   
                     θ 
                     xz 
                     ′ 
                   
                   = 
                   
                     
                       tan 
                       
                         - 
                         1 
                       
                     
                     ( 
                     
                       
                         
                           d 
                           x 
                         
                         
                           l 
                           xz 
                         
                       
                       + 
                       
                         tan 
                         ⁢ 
                         
                           θ 
                           xz 
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   1 
                 
               
             
           
         
       
       
         
           
             
               
                 
                   
                     θ 
                     yz 
                     ′ 
                   
                   = 
                   
                     
                       tan 
                       
                         - 
                         1 
                       
                     
                     ( 
                     
                       
                         
                           d 
                           y 
                         
                         
                           l 
                           yz 
                         
                       
                       + 
                       
                         tan 
                         ⁢ 
                         
                           θ 
                           yz 
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   2 
                 
               
             
           
         
       
     
     In Equation 1, θ′ xz  denotes the angle of reflection from the LIS  315  on the x-z plane to the terminal  225 , d x  denotes an x-axis interval between the LIS  315  and the LIS  325 , l xz  denotes the distance perpendicular to the terminal  225  and the x-axis on the x-z plane, and θ xz  denotes the angle of incidence of radio wave incident from the terminal  225  to the reference LIS, for example, the LIS  325 , for the first preamble signal on the plane on which the terminal  225  is projected on the x-z plane. 
     In Equation 2, θ′ yz  denotes the angle of reflection from the LIS  320  on the y-z plane to the terminal  225 , d y  denotes a y-axis interval between the LIS  320  and the LIS  325 , l yz  denotes the distance perpendicular to the terminal  225  and the y-axis on the y-z plane, and θ yz  denotes the angle of incidence of radio wave incident from the terminal  225  to the reference LIS, for example, the LIS  325 , for the first preamble signal on the plane on which the terminal  225  is projected on the y-z plane. 
     If the x-axis interval and the y-axis interval between the plurality of LISs  310 ,  315 ,  320 , and  325  are the same, Equation 1 and Equation 2 may be generalized to Equation 3 and Equation 4, respectively. 
     
       
         
           
             
               
                 
                   
                     θ 
                     xz 
                     ′ 
                   
                   = 
                   
                     
                       tan 
                       
                         - 
                         1 
                       
                     
                     ( 
                     
                       
                         
                           
                             d 
                             x 
                           
                           
                             l 
                             xz 
                           
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               n 
                               x 
                             
                             - 
                             1 
                           
                           ) 
                         
                       
                       + 
                       
                         tan 
                         ⁢ 
                         
                           θ 
                           xz 
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   3 
                 
               
             
           
         
       
       
         
           
             
               
                 
                   
                     θ 
                     yz 
                     ′ 
                   
                   = 
                   
                     
                       tan 
                       
                         - 
                         1 
                       
                     
                     ( 
                     
                       
                         
                           
                             d 
                             y 
                           
                           
                             l 
                             yz 
                           
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               n 
                               y 
                             
                             - 
                             1 
                           
                           ) 
                         
                       
                       + 
                       
                         tan 
                         ⁢ 
                         
                           θ 
                           yz 
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   4 
                 
               
             
           
         
       
     
     In Equation 3, θ′ xz  denotes the angle of reflection from the LIS  315  on the x-z plane to the terminal  225 , d x  denotes the x-axis interval between the LIS  315  and the LIS  325 , l xz  denotes the distance perpendicular to the terminal  225  and the x-axis on the x-z plane, θ xz  denotes the angle of incidence of radio wave incident from the terminal  225  to the reference LIS, for example, the LIS  325 , for the first preamble signal on the plane on which the terminal  225  is projected on the x-z plane, and n x  denotes a number of LISs provided to the x-axis. For example, in  FIG.  6   , n x  is 2. 
     In Equation 4, θ′ yz  denotes the angle of reflection from the LIS  320  on the y-z plane to the terminal  225 , d y  denotes the y-axis interval between the LIS  320  and the LIS  325 , l yz  denotes the distance perpendicular to the terminal  225  and the y-axis on the y-z plane, θ yz  denotes the angle of incidence of radio wave incident from the terminal  225  to the reference LIS, for example, the LIS  325 , for the first preamble signal on the plane on which the terminal  225  is projected on the y-z plane, and n y  denotes a number of LISs provided to the y-axis. For example, in  FIG.  6   , n y  is 2. 
     With the assumption that the terminal  225  and the LISs  310 ,  315 ,  320 , and  325  are present on a line-of-sight (LOS), the distance (l xz ) between the terminal  225  and the x-z plane and the distance (l yz ) between the terminal  225  and the y-z plane may be calculated using an FSL model. The FSL model may be represented as the following Equation 5. 
     
       
         
           
             
               
                 
                   
                     F 
                     ⁢ 
                     S 
                     ⁢ 
                     L 
                   
                   = 
                   
                     
                       D 
                       t 
                     
                     ⁢ 
                     
                       
                         
                           D 
                           r 
                         
                         ( 
                         
                           λ 
                           
                             4 
                             ⁢ 
                             π 
                             ⁢ 
                             d 
                           
                         
                         ) 
                       
                       2 
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   5 
                 
               
             
           
         
       
     
     Here, FSL denotes free space loss, D t  and D r  denote a directivity gain of a transmission antenna and a directivity gain of a reception antenna, respectively, λ denotes a wavelength of a signal, and d denotes a distance between an LIS and the terminal  225 . For example, d denotes the distance between the reference LIS, for example, the LIS  325 , for the first preamble signal and the terminal  225 . 
     Calculating the reception power (P r ) of the LIS using the FSL model, it may be represented as Equation 6. 
     
       
         
           
             
               
                 
                   
                     P 
                     r 
                   
                   = 
                   
                     
                       P 
                       t 
                     
                     ⁢ 
                     
                       D 
                       t 
                     
                     ⁢ 
                     
                       
                         
                           D 
                           r 
                         
                         ( 
                         
                           λ 
                           
                             4 
                             ⁢ 
                             π 
                             ⁢ 
                             d 
                           
                         
                         ) 
                       
                       2 
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   6 
                 
               
             
           
         
       
     
     In Equation 6, P t  denotes a transmission power (e.g., transmission power of the first preamble signal) of the terminal  225 , P r  denotes a reception power (e.g., reception power of the first preamble signal) of the reference LIS, for example, the LIS  325 , for the first preamble signal, D t  and D r  denote the directivity gain of the transmission antenna and the directivity gain of the reception antenna, respectively, λ denotes the wavelength of the signal, and d denotes the distance between the reference LIS, for example, the LIS  325 , for the first preamble signal and the terminal  225 . 
     In general, since the terminal  225  transmits a signal according to a target power set in the base station  230  during 5G communication, a value of P t  may be known by the wireless communication system  200 . If the reception power through the LIS of the first preamble signal transmitted from the terminal  225  is P r , the distance (d) may be represented as Equation 7. 
     
       
         
           
             
               
                 
                   d 
                   = 
                   
                     
                       λ 
                       
                         4 
                         ⁢ 
                         π 
                       
                     
                     ⁢ 
                     
                       
                         
                           
                             P 
                             t 
                           
                           
                             P 
                             r 
                           
                         
                         ⁢ 
                         
                           D 
                           t 
                         
                         ⁢ 
                         
                           D 
                           r 
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   7 
                 
               
             
           
         
       
     
     In Equation 7, D t  and D r  denote the directivity gain of the transmission antenna and the directivity gain of the reception antenna, respectively, λ denotes the wavelength of the signal, d denotes the distance between the reference LIS, for example, the LIS  325 , for the first preamble signal and the terminal  225 , P t  denotes the transmission power of the first preamble signal of the terminal  225 , and P r  denotes the reception power of the first preamble signal through the reference LIS, for example, the LIS  325 , for the first preamble signal. 
     The distance (l xz ) and the distance (l yz ) using a trigonometric function are relational expressions including the distance (d) and may be represented as Equation 8 and Equation 9, respectively. 
       l xz =d sin θ xz   Equation 8
 
       l yz =d sin θ yz   Equation 9
 
     In Equation 8, l xz  denotes the distance perpendicular to the terminal  225  and the x-axis on the x-z plane, d denotes the distance between the reference LIS, for example, the LIS  325 , for the first preamble signal and the terminal  225 , and θ xz  denotes the angle of incidence of radio wave incident from the terminal  225  to the reference LIS, for example, the LIS  325 , for the first preamble signal on the plane on which the terminal  225  is projected on the x-z plane. 
     In Equation 9, l yz  denotes the distance perpendicular to the terminal  225  and the y-axis on the y-z plane, d denotes the distance between the reference LIS, for example, the LIS  325 , for the first preamble signal and the terminal  225 , and θ yz  denotes the angle of incidence of radio wave incident from the terminal  225  to the reference LIS, for example, the LIS  325 , for the first preamble signal on the plane on which the terminal  225  is projected on the y-z plane. 
     In an example embodiment, the LIS server  220  may correct the angle of reflection of each of the plurality of LISs  310 ,  315 , and  320  using Equation 1 to Equation 9 and may control the plurality of LISs  310 ,  315 , and  320  according to the corrected angle of reflection. The LIS server  220  may correct the angle of reflection of each of the plurality of LISs  310 ,  315 , and  320  and may deliver the data service signal transmitted from the base station  230  to the terminal  225  with high efficiency. 
     Hereinafter, an example embodiment of providing communication for a plurality of terminals in the wireless communication system  200  is described with reference to  FIGS.  7 A and  7 B . 
       FIGS.  7 A and  7 B  illustrate a location method and a positioning method for a plurality of terminals in a communication system according to various embodiments of the disclosure. 
     Referring to  FIG.  7 A , a plurality of LISs  310 ,  315 ,  320 , and  325 , the LIS controller  305  configured to control the plurality of LISs  310 ,  315 ,  320 , and  325 , a first terminal  753  configured to transmit a first preamble signal, and a second terminal  755  configured to transmit a second preamble signal are illustrated. 
     Referring to  FIG.  7 A , the plurality of LISs  310 ,  315 ,  320 , and  325  may be controlled by the LIS controller  305  and set to receive a radio wave in different directions, for example, radio wave reception directions  730 ,  735 ,  740 , and  745 , respectively. However, it is provided as an example only. In another example embodiment, at least some of the plurality of LISs  310 ,  315 ,  320 , and  325  may be set to receive a radio wave in the same direction. 
     The first terminal  753  may be beamformed in a specific direction through a multi-antenna of the first terminal  753  and may transmit the first preamble signal, and the second terminal  755  may be beamformed in a specific direction through a multi-antenna of the second terminal  755  and may transmit the second preamble signal. 
     The first preamble signal transmitted from the first terminal  753  may be received through the LISs  320  and  325  among the plurality of LISs  310 ,  315 ,  320 , and  325 , and the second preamble signal transmitted from the second terminal  755  may be received through the LISs  310  and  315  among the plurality of LISs  310 ,  315 ,  320 , and  325 . 
     Although the plurality of LISs  320  and  325  may receive the first preamble signal and the plurality of LISs  310  and  315  may receive the second preamble signal, they may differ from each other in terms of reception power. The LIS  325  of which the radio wave reception direction  745  is directed toward the first terminal  753  may receive the first preamble signal with relatively high reception power and the LIS  320  may receive the first preamble signal with reception power lower than that of the LIS  325 . 
     The LIS  310  of which the radio wave reception direction  730  is directed toward the second terminal  755  may receive the second preamble signal with relatively high reception power and the LIS  315  may receive the second preamble signal with reception power lower than that of the LIS  310 . 
     The plurality of LISs  320  and  325  and the plurality of LISs  310  and  315  have different radio wave reception directions and, here, the plurality of LISs  320  and  325  may not receive the second preamble signal and the plurality of LISs  310  and  315  may not receive the first preamble signal. 
     The first preamble signal and the second preamble signal received through at least some of the plurality of LISs  310 ,  315 ,  320 , and  325  may be delivered to the LIS controller  305  through the LIS receiver  510 . The LIS receiver  510  may demodulate the received first preamble signal and second preamble signal and may convert the same to a digital signal. The LIS controller  305  may receive, from the LIS receiver  510 , and process the first preamble signal and the second preamble signal each converted to the digital signal. 
     In an example embodiment, the LIS controller  305  may tag and store preamble information included in the first preamble signal received through each of the LISs  320  and  325  and identification information of the first preamble signal for each of the LISs  320  and  325  with information on an angle of incidence corresponding to the radio wave reception direction  740 ,  745  of each LIS  320 ,  325 , and delay time information and reception power information of the first preamble signal. For example, the LIS controller  305  may tag preamble information and identification information of the first preamble signal received through the LIS  325 , information on the angle of incidence corresponding to the radio wave reception direction  745  of the LIS  325 , and the delay time information and the reception power information of the first preamble signal received through the LIS  325 , as information on the LIS  325  and may store the same in the LIS server  220 . The preamble information included in the first preamble signal may include identification information of the first terminal  753  that requests a data service. 
     In an example embodiment, the LIS controller  305  may tag preamble information included in the second preamble signal received through each of the LISs  310  and  315  and identification information of the second preamble signal for each of the LISs  310  and  315  with information on the angle of incidence corresponding to the radio wave reception direction  730 ,  735 , and delay time information and reception power information of the second preamble signal of each LIS  310  and  315 . For example, the LIS controller  305  may tag preamble information and identification information of the second preamble signal received through the LIS  310 , information on the angle of incidence corresponding to the radio wave reception direction  730  of the LIS  310 , and delay time information and reception power information of the second preamble signal received through the LIS  310  as information on the LIS  310 , and may store the same in the LIS server  220 . The preamble information included in the second preamble signal may include identification information of the second terminal  755  that request the data service. 
     The LIS server  220  may compare the reception power of the first preamble signal received through each of the plurality of LISs  310 ,  315 ,  320 ,  325  and may determine the LIS  325  corresponding to the largest reception power of the first preamble signal as a first reference LIS for the first preamble signal, and may determine an angle of incidence corresponding to the radio wave reception direction  745  of the corresponding LIS  325  as a first reference angle of incidence for the first preamble signal. 
     The LIS server  220  may compare the reception power of the second preamble signal received through each of the plurality of LISs  310 ,  315 ,  320 , and  325 , may determine the LIS  310  corresponding to the largest reception power of the second preamble signal as a second reference LIS for the second preamble signal, and may determine an angle of incidence corresponding to the radio wave reception direction  730  of the corresponding LIS  310  as a second reference angle of incidence for the corresponding second preamble signal. 
     Referring to  FIG.  7 B , the LIS server  220  may control an angle of reflection at which a data service signal transmitted from the base station  230  to the corresponding first terminal  753  and second terminal  755  is reflected by each of the plurality of LISs  310 ,  315 ,  320 , and  325 , based on the first reference angle of incidence and the second reference angle of incidence. 
       FIG.  7 B  illustrates reflection directions  730 ,  760 ,  765 , and  745  in which the angle of reflection at which the data service signal transmitted from the base station  230  is reflected by the plurality of LISs  310 ,  315 ,  320 , and  325  are controlled based on the first reference angle of incidence and the second reference angle of incidence determined in  FIG.  7 A . 
     In an example embodiment, the base station  230  may receive preamble signals transmitted from the first terminal  753 , including the first preamble signal, and may receive preamble signals transmitted from the second terminal  755 , including the second preamble signal. The base station  230  may transmit identification information of the first preamble signal corresponding to the largest reception power among the preamble signals transmitted from the first terminal  753  to the LIS controller  305  and may transmit identification information of the second preamble signal corresponding to the largest reception power among the preamble signals transmitted from the second terminal  755  to the LIS controller  305 . 
     In an example embodiment, the LIS controller  305  may receive the identification information of the first preamble signal and the identification information of the second preamble signal from the base station  230 . The LIS controller  305  and the base station  230  may be connected in a wired or wireless manner. 
     In an example embodiment, when the LIS controller  305  receives identification information of at least two preamble signals from the base station  230 , the LIS controller  305  may divide the plurality of LISs  310 ,  315 ,  320 , and  325  into a number of groups corresponding to a number of the received identification information and may control the same for each group. 
     For example, the LIS controller  305  may control the LISs  320  and  325 , such that an angle of reflection at which the data service signal transmitted from the base station  230  is reflected by each of the LISs  320  and  325  receiving the first preamble signal corresponds to the first reference angle of incidence of the first preamble signal, based on the identification information of the first preamble signal. 
     The LIS controller  305  may control the LISs  310  and  315  such that an angle of reflection at which the data service signal transmitted from the base station  230  is reflected by each of the LISs  310  and  315  receiving the second preamble signal corresponds to the second reference angle of incidence of the second preamble signal, based on identification information of the second preamble signal. 
     In an example embodiment, when a distance between each of the LISs  320  and  325  and the first terminal  753  is distant, the LIS controller  305  may control the angle of reflection of each of the LISs  320  and  325  to be the same. When the distance between each of the LISs  320  and  325  and the first terminal  753  is close, the LIS controller  305  may correct the angle of reflection of each of the LISs  320  and  325  and control the reflected data service signal to be directed toward the first terminal  753 . The distance between each of the LISs  320  and  325  and the first terminal  753  may be determined based on reception power of the first preamble signal of the first reference LIS, for example, the LIS  325 . 
     In an example embodiment, when a distance between each of the LISs  310  and  315  and the second terminal  755  is distant, the LIS controller  305  may control the angle of reflection of each of the LISs  310  and  315  to be the same. When the distance between each of the LISs  310  and  315  and the second terminal  755  is close, the LIS controller  305  may correct the angle of reflection of each of the LISs  310  and  315  and may control the reflected data service signal to be directed toward the second terminal  755 . The distance between each of the LISs  310  and  315  and the second terminal  755  may be determined based on reception power of the second preamble signal of the second reference LIS, for example, the LIS  310 . 
     When the determined distance is greater than or equal to a threshold, the LIS controller  305  may determine that the distance is distant. When the determined distance is less than the threshold, the LIS controller  305  may determine that the distance is close. 
     Hereinafter, a detailed operation of a communication method using an LIS is described with reference to  FIG.  8   . 
       FIG.  8    is a flowchart illustrating a communication method using an LIS according to an embodiment of the disclosure. 
     Referring to  FIG.  8   , in operation  805 , an LIS server (e.g., the LIS server  220  of  FIG.  2   ) may receive at least one preamble signal among preamble signals transmitted from a terminal (e.g., the terminal  225  of  FIG.  2   ) using an LIS (e.g., the LIS  310  of  FIG.  3   ). For example, the LIS server may receive a first preamble signal using a plurality of LISs (e.g., the plurality of LISs  310 ,  315 ,  320 , and  325  of  FIG.  3   ) each of which a radio wave reception direction is differently set. 
     The LIS server may tag and store preamble information of the first preamble signal received through the plurality of LISs and identification information of the first preamble signal for each LIS with information on an angle of incidence corresponding to a radio wave reception direction of each LIS, and delay time information and reception power information of the first preamble signal received through each LIS. 
     In operation  810 , the LIS server may determine a reference angle of incidence at which the first preamble signal transmitted from the terminal is received through the LIS. For example, the LIS server may determine the LIS that receives the first preamble signal with the largest reception power among the plurality of LISs and may determine the angle of incidence corresponding to the radio wave reception direction of the determined LIS as a reference angle of incidence of the first preamble signal. 
     In an example embodiment, operations  805  and  810  may correspond to operation  405  of  FIG.  4    corresponding to a location operation. 
     In operation  815 , a base station (e.g., the base station  230  of  FIG.  2   ) may receive preamble signals transmitted from the terminal, including the first preamble signal reflected by the LIS. When the base station receives the preamble signals, the base station may determine the terminal that requests a data service based on the received preamble signals. 
     In operation  820 , the base station may determine a preamble signal having the largest reception power among the received preamble signals. That the reception power is largest may represent that a signal is delivered with the best efficiency among a plurality of radio wave delivery paths. 
     In operation  825 , the base station may transmit identification information of the determined preamble signal to the LIS server. For example, the base station may transmit identification information of the first preamble signal having the largest reception power among the received preamble signals to the LIS server. 
     In operation  830 , the LIS server may control the LIS such that an angle of reflection of a data service signal transmitted from the base station corresponds to a reference angle of incidence for the corresponding terminal, based on the identification information received from the base station. 
     In an example embodiment, when a preamble signal corresponding to the identification information received from the base station is present in at least one preamble signal received through the LIS, the LIS server may control the LIS such that the angle of reflection at which the data service signal transmitted from the base station is reflected by the LIS corresponds to an angle of incidence at which the preamble signal of the corresponding identification information is incident. 
     For example, the LIS server may control the plurality of LISs such that the angle of reflection at which the data service signal transmitted from the base station corresponds to the reference angle of incidence of the first preamble signal, based on the reference angle of incidence of the first preamble signal corresponding to the received preamble identification information. 
     In an example embodiment, operations  815 ,  820 ,  825 , and  830  may be included in operation  410  of  FIG.  4    corresponding to a positioning operation. 
     Hereinafter, a signal flow among a base station, an LIS device, and a terminal included in the wireless communication system  200  is described with reference to  FIG.  9   . 
       FIG.  9    is a flowchart illustrating a communication method using an LIS performed by a base station, an LIS device, and a terminal in a communication system according to an embodiment of the disclosure. 
     Referring to  FIG.  9   , a signal flow among the base station  230 , an LIS device  905 , and the terminal  225  is illustrated. The LIS device  905  may include a plurality of LISs (e.g., the plurality of LISs  310 ,  315 ,  320 , and  325  of  FIG.  3   ) and an LIS server (e.g., the LIS server  220  of  FIG.  2   ). 
     In operation  910 , the base station  230  may transmit a synchronization signal for downlink establishment. In operation  915 , the synchronization signal may be reflected in various directions by the plurality of LISs and then delivered to the terminal  225 . 
     The terminal  225  may receive the reflected synchronization signal in various directions through beam sweeping. 
     In operation  920 , the terminal  225  may transmit preamble signals in various directions in which the synchronization signal is received. The preamble signals may be received and reflected through the LIS. In operation  925 , the preamble signals transmitted from the terminal  225  may be delivered to the base station  230  through a multipath including a path through which the preamble signals are reflected by the LIS. 
     The LIS server may receive at least one preamble signal among the preamble signals transmitted from the terminal  225  through the plurality of LISs. For example, the LIS server may receive the first preamble signal transmitted from the terminal  225  through the plurality of LISs. The first preamble signal received through the plurality of LISs may be delivered to the LIS server. 
     In operation  940 , the LIS server may detect preamble information and identification information from the first preamble signal. 
     In operation  945 , the LIS server may tag and store the preamble information and the identification information included in the first preamble signal, information on an angle of incidence corresponding to a radio wave reception direction of the LIS that receives the first preamble signal, and delay time information and reception power information of the first preamble signal received through the corresponding LIS as information on the corresponding LIS. 
     The LIS server may compare the reception power of the first preamble signal received through each of the plurality of LISs, may determine the LIS corresponding to the largest reception power of the first preamble signal as a reference LIS for the first preamble signal, and may determine an angle of incidence corresponding to a radio wave reception direction of the corresponding LIS as a reference angle of incidence for the first preamble signal. 
     When the base station  230  receives the preamble signals delivered in operation  925 , the base station  230  may detect preamble information and identification information of the preamble signals, in operation  930 . In operation  935 , the base station  230  may determine the terminal  225  that requests a data service based on the detected preamble information. The base station  230  may transmit a data service signal for the determined terminal  225   
     In operation  950 , the base station  230  may determine a preamble signal having the largest reception power among the received preamble signals and may transmit identification information of the determined preamble signal to the LIS server. For example, the base station  230  may transmit identification information of the first preamble signal having the largest reception power among the received preamble signals to the LIS server. 
     When the LIS server receives the identification information of the preamble signal, the LIS server may perform a positioning operation for the terminal  225  that requests the data service, in operation  955 . Description related to the positioning operation is made above with reference to  FIG.  4    and  FIG.  5 B  and thus, repeated description is omitted. 
     When the positioning operation is completed in operation  955 , the data service signal transmitted from the base station  230  may be reflected by the LIS and concentrated in a direction in which the terminal  225  is present. 
     In operation  960 , the terminal  225  may receive the data service signal with high reception power by receiving the data service signal in a direction in which the preamble signal is transmitted in operation  920 . 
     A method for wireless communication using an LIS (e.g., the LIS  325 ) may include transmitting, by the terminal  225 , preamble signals each with a different transmission time and transmission direction, receiving, by the LIS server  220 , at least one preamble signal among the preamble signals through an LIS (e.g., the LIS  325 ) through which an incident radio wave is received and reflected and determining a reference angle of incidence for the at least one preamble signal, receiving, by the base station  230 , the preamble signals that are delivered through a multipath from the terminal  225 , transmitting, by the base station  230 , identification information of a preamble signal having the largest reception power among the received preamble signals to the LIS server  220 , and when the at least one preamble signal includes a preamble signal corresponding to the identification information received from the base station  230 , controlling, by the LIS server  220 , the LIS (e.g., the LIS  325 ) such that an angle of reflection at which a data service signal transmitted from the base station  230  is reflected by the LIS (e.g., the LIS  325 ) corresponds to the reference angle of incidence determined for the preamble signal of the identification information. 
     The determining of the reference angle of incidence may include receiving, by the LIS server  220 , the at least one preamble signal transmitted from the terminal  225  using the plurality of LISs  310 ,  315 ,  320 , and  325  each of which a different radio wave reception direction is differently set, and determining, by the LIS server  220 , the reference angle of incidence for the at least one preamble signal based on the radio wave reception direction  535 ,  540 ,  545 ,  550  of each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the reception power of the at least one preamble signal. 
     The determining of the reference angle of incidence for the at least one preamble signal based on the radio wave reception direction and the reception power may include determining an LIS (e.g., the LIS  325 ) through which a first preamble signal included in the at least one preamble signal is received with the largest reception power among the plurality of LISs  310 ,  315 ,  320 , and  325 , and determining, by the LIS server  220 , an angle of incidence corresponding to the radio wave reception direction (e.g., the radio wave reception direction  550 ) of the determined LIS (e.g., the LIS  325 ) as the reference angle of incidence of the first preamble signal. 
     The controlling of the LIS may include, when the at least one preamble signal includes a preamble signal corresponding to the identification information received from the base station  230 , controlling, by the LIS server  220 , the plurality of LISs  310 ,  315 ,  320 , and  325  such that an angle of reflection at which the data service signal transmitted from the base station  230  is reflected by each of the plurality of LISs  310 ,  315 ,  320 , and  325  corresponds to the reference angle of incidence determined for the preamble signal of the identification information. 
     The controlling of the plurality of LISs  310 ,  315 ,  320 , and  325  may include determining a distance between the terminal  225  and each of the plurality of LISs  310 ,  315 ,  320 , and  325 , determining whether the distance is close, and when the distance is determined to be close, correcting the angle of reflection at which the data service signal transmitted from the base station  230  is reflected by each of the plurality of LISs  310 ,  315 ,  320 , and  325 . 
     The determining of the distance may include determining the distance based on the largest reception power among reception powers of the one or more preamble signals received through the plurality of LISs  310 ,  315 ,  320 , and  325 , and the determining whether the distance is close may include determining that the distance is distant when the determined distance is greater than or equal to a threshold. 
     The correcting may include correcting the angle of reflection of each of the plurality of LISs  310 ,  315 ,  320 , and  325  based on a distance between the plurality of LISs  310 ,  315 ,  320 , and  325  and the reference angle of incidence determined for the preamble signal of the identification information. 
     The LIS (e.g., the LIS  325 ) may be attached to an exterior wall of a building. 
     The method for wireless communication may further include transmitting, by the base station  230 , a synchronization signal, receiving, by the terminal  225 , the synchronization signal reflected by the plurality of LISs  310 ,  315 ,  320 , and  325  in a plurality of directions, and transmitting, by the terminal  225 , the preamble signals in the plurality of directions. 
     The method for wireless communication may further include transmitting, by the base station  230 , the data service signal, and receiving, by the terminal  225 , the data service signal reflected by the plurality of LISs  310 ,  315 ,  320 , and  325 . 
     The wireless communication system  200  using an LIS according to an example embodiment may include the terminal  225 , the base station  230 , an LIS (e.g., the LIS  325 ) including a meta-surface and in which an angle of reflection of an incident radio wave is adjusted according to an electrical stimulation, and the LIS server  220  configured to control the LIS (e.g., the LIS  325 ). The terminal  225  may transmit preamble signals each with a different transmission time and transmission direction, the LIS server  220  may receive at least one preamble signal among the preamble signals through the LIS (e.g., the LIS  325 ) and may determine a reference angle of incidence for the at least one preamble signal, the base station  230  may receive the preamble signals that are delivered through a multipath from the terminal  225 , and may transmit identification information of a preamble signal having the largest reception power among the received preamble signals to the LIS server  220 , and when the at least one preamble signal includes a preamble signal corresponding to the identification information received from the base station  230 , the LIS server  220  may control the LIS (e.g., the LIS  325 ) such that an angle of reflection at which a data service signal transmitted from the base station  230  is reflected by the LIS (e.g., the LIS  325 ) corresponds to the reference angle of incidence determined for the preamble signal of the identification information. 
     The LIS server  220  may receive the at least one preamble signal transmitted from the terminal  225  using the plurality of LISs  310 ,  315 ,  320 , and  325  each of which a radio wave reception direction is differently set, and may determine the reference angle of incidence for the at least one preamble signal based on the radio wave reception direction  535 ,  540 ,  545 ,  550  of each of the plurality of LISs  310 ,  315 ,  320 , and  325  and the reception power of the at least one preamble signal. 
     The LIS server  220  may determine an LIS (e.g., the LIS  325 ) through which a first preamble signal included in the at least one preamble signal is received with the largest reception power among the plurality of LISs  310 ,  315 ,  320 , and  325 , and may determine an angle of incidence corresponding to the radio wave reception direction (e.g., the radio wave reception direction  550 ) of the determined LIS (e.g., the LIS  325 ) as the reference angle of incidence of the first preamble signal. 
     The LIS server  220  may tag and store reception power information of each of the plurality of LISs  310 ,  315 ,  320 , and  325  through which the first preamble signal is received, delay time information of the first preamble signal, identification information of the first preamble signal, and information on an angle of incidence corresponding to the radio wave reception direction of each LIS. 
     When the at least one preamble signal includes a preamble signal corresponding to the identification information received from the base station  230 , the LIS server  220  may control the plurality of LISs  310 ,  315 ,  320 , and  325  such that an angle of reflection at which the data service signal transmitted from the base station  230  is reflected by each of the plurality of LISs  310 ,  315 ,  320 , and  325  corresponds to the reference angle of incidence determined for the preamble signal of the identification information. 
     The LIS server  220  may determine a distance between the terminal  225  and each of the plurality of LISs  310 ,  315 ,  320 , and  325 , may determine whether the distance is close, and when the distance is determined to be close, correct the angle of reflection at which the data service signal transmitted from the base station  230  is reflected by each of the plurality of LISs  310 ,  315 ,  320 , and  325 . 
     The LIS server  220  may determine the distance based on the largest reception power among reception powers of the one or more preamble signals received through the plurality of LISs  310 ,  315 ,  320 , and  325 , and may determine that the distance is distant when the determined distance is greater than or equal to a threshold. 
     The LIS server  220  may correct the angle of reflection of each of the plurality of LISs  310 ,  315 ,  320 , and  325  based on a distance between the plurality of LISs  310 ,  315 ,  320 , and  325  and the reference angle of incidence determined for the preamble signal of the identification information. 
     The base station  230  may transmit a synchronization signal, and the terminal  225  may receive the synchronization signal reflected by the plurality of LISs  310 ,  315 ,  320 , and  325  in a plurality of directions, and may transmit the preamble signals in the plurality of directions. 
     The electronic device according to various example embodiments may be one of various types of electronic devices. The electronic device may include, for example, a portable communication device (e.g., a smartphone), a computer device, a portable multimedia device, a portable medical device, a camera, a wearable device, or a home appliance device. According to an example embodiment of the disclosure, the electronic device is not limited to those described above. 
     It should be appreciated that various example embodiments of the disclosure and the terms used therein are not intended to limit the technological features set forth herein to particular example embodiments and include various changes, equivalents, or replacements for a corresponding example embodiment. In connection with the description of the drawings, like reference numerals may be used for similar or related components. As used herein, “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “A, B, or C,” each of which may include any one of the items listed together in the corresponding one of the phrases, or all possible combinations thereof. Terms such as “first”, “second”, or “first” or “second” may simply be used to distinguish the component from other components in question, and do not limit the components in other aspects (e.g., importance or order). It is to be understood that if an element (e.g., a first element) is referred to, with or without the term “operatively” or “communicatively”, as “coupled with,” “coupled to,” “connected with,” or “connected to” another element (e.g., a second element), it means that the element may be coupled with the other element directly (e.g., by wire), wirelessly, or via a third element. 
     As used in connection with various example embodiments of the disclosure, the term “module” may include a unit implemented in hardware, software, or firmware, and may interchangeably be used with other terms, for example, “logic,” “logic block,” “part,” or “circuitry”. A module may be a single integral component, or a minimum unit or part thereof, adapted to perform one or more functions. For example, according to an example embodiment, the module may be implemented in a form of an application-specific integrated circuit (ASIC). 
     Various example embodiments as set forth herein may be implemented as software (e.g., the program  140 ) including one or more instructions that are stored in a storage medium (e.g., an internal memory  136  or an external memory  138 ) that is readable by a machine (e.g., the electronic device  101 ) For example, a processor (e.g., the processor  120 ) of the machine (e.g., the electronic device  101 ) may invoke at least one of the one or more instructions stored in the storage medium, and execute it. This allows the machine to be operated to perform at least one function according to the at least one instruction invoked. The one or more instructions may include a code generated by a complier or a code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term “non-transitory” simply means that the storage medium is a tangible device, and does not include a signal (e.g., an electromagnetic wave), but this term does not differentiate between where data is semi-permanently stored in the storage medium and where the data is temporarily stored in the storage medium. 
     According to an example embodiment, a method according to various example embodiments of the disclosure may be included and provided in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or be distributed (e.g., downloaded or uploaded) online via an application store (e.g., PlayStore™), or between two user devices (e.g., smart phones) directly. If distributed online, at least part of the computer program product may be temporarily generated or at least temporarily stored in the machine-readable storage medium, such as memory of the manufacturer&#39;s server, a server of the application store, or a relay server. 
     According to various example embodiments, each component (e.g., a module or a program) of the above-described components may include a single entity or multiple entities, and some of the multiple entities may be separately disposed in different components. According to various example embodiments, one or more of the above-described components may be omitted, or one or more other components may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, according to various example embodiments, the integrated component may still perform one or more functions of each of the plurality of components in the same or similar manner as they are performed by a corresponding one of the plurality of components before the integration. According to various example embodiments, operations performed by the module, the program, or another component may be carried out sequentially, in parallel, repeatedly, or heuristically, or one or more of the operations may be executed in a different order or omitted, or one or more other operations may be added. 
     While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.