KR20110077663A - Method for determining cell edge area and reducing interference in communication between enodeb and mobile terminal - Google Patents

Abstract

PURPOSE: A cell boundary area decision method and reducing interference method on communication are provide to decide whether a mobile terminal is located in the cell boundary area of a mobile terminal base-station based on a RTT(Round Trip time) value or not. CONSTITUTION: An EPC(Evolved Packet Core) receives the RTT(Round Trip Time) value from a first base-station(302). The EPC decides whether the mobile terminal locates based on the RTT value in the cell boundary area of the first base-station or not(304). The EPC starts a procedure of reducing interference on communication between the mobile terminal and the first base-station when the mobile terminal is located in the cell boundary. The procedure of reducing interference on communication that is between the mobile terminal and the first base-station comprises coordinated multiple point transmission/reception technique.

Description

How to determine cell boundary area and reduce communication interference {METHOD FOR DETERMINING CELL EDGE AREA AND REDUCING INTERFERENCE IN COMMUNICATION BETWEEN eNodeB AND MOBILE TERMINAL}

The present invention relates to a mobile communication network, and more particularly, to a method for determining a cell boundary region in a mobile communication network and a method for reducing communication interference.

Recently, due to the rapid development of communication, computer network, and semiconductor technology, various services using wireless communication networks are not only provided, but the demands of consumers are increasing day by day, and the global mobile communication technology is exploding. to be. In response to this diversified wireless communication technology, many organizations in Europe, Japan, the United States, and China are forming 3GPP (3rd Generation Project Group) to develop international standard technology. 3GPP recently completed research on LTE-Advanced system that has almost completed standardization of Long Term Evolution (LTE) system based on new wireless access technology and meets IMT-Advanced requirements of International Telecommunications Union-Radio (ITU-R). I'm going.

On the other hand, as the demand for the quality of wireless communication service increases due to the rapid development of the communication environment, there is an increasing need for performance improvement for cell edge users, which suffer from SINR attenuation far from the base station. In LTE-Advanced system, various techniques for improving the communication performance at the cell boundary area have been discussed, among them, Coordinated Multipoint Transmission and Reception (CoMP) technology and Inter-Cell Interference Management (ICIM; Inter). Cell Interference Management technology. The cooperative multipoint transmission / reception technique is a cooperative transmission technique between base stations in order to improve performance of a cell boundary user, and there is a joint transmission scheme in which a plurality of base stations simultaneously transmit data to one terminal. Inter-Cell Interference Management (ICIM) technology is designed to reduce or eliminate the cause of interference by reducing the transmission power of the corresponding base station in the neighboring cell causing the interference or switching to another base station, and for the specific base station to perform dynamic scheduling. A method of controlling interference by differently allocating and arranging transmission / reception resources of several cells geographically separated using the same.

Meanwhile, in a method in which a cooperative multipoint transmission / reception technique operates, such as a combined transmission scheme, it is generally determined whether the terminal is located at a cell boundary region based on a pathloss measurement between the terminal and the base station. However, in addition to the case where the terminal is actually located in the cell boundary region, there may be a case where the path loss measurement value is increased under certain RF conditions. In this case, frequent cooperative multipoint transmission and reception operations can be generated to increase the load on the network.

In addition, in the conventional cooperative multi-point transmission and reception technology, the combined transmission scheme is mainly based on transmit diversity (Tx Diversity), and the improvement in cell performance is insignificant, requiring a further improved technology.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and the method of reducing interference in communication and determining whether the mobile terminal is located in the cell boundary region of the base station based on the RTT value and operating in MIMO Provided is a method of applying combined transmission among cooperative multipoint transmission / reception techniques to a base station and a terminal.

According to an embodiment of the present invention, a method for determining whether a mobile terminal is located in a cell boundary region of a base station is provided. In a mobile communication system comprising a mobile terminal, a plurality of base stations, a first base station of the plurality of base stations to control the mobile terminal and an Evolved Packet Core (EPC) coupled to communicate with the plurality of base stations, CLAIMS 1. A method of determining whether a mobile terminal is located at a cell boundary of a base station, the method comprising: receiving, by the EPC, a Round Trip Time (RTT) value of the mobile terminal from the first base station; And determining, by the EPC, whether the mobile terminal is located at a cell boundary of the first base station based on the RTT value.

In one embodiment, a method of reducing interference in communication between a mobile terminal and a base station is provided. In a mobile communication system comprising a mobile terminal, a plurality of base stations, a first base station of the plurality of base stations to control the mobile terminal, and an Evolved Packet Core (EPC) coupled to communicate with the plurality of base stations. A method of reducing interference in communication between the mobile station and the first base station when located in a cell boundary region of the first base station, wherein the EPC is a round trip time (RTT) value of the mobile station from the first base station. Receiving; Determining, by the EPC, whether the mobile terminal is located at a cell boundary of the first base station based on the RTT value; And initiating, by the EPC, a process of reducing interference in communication between the mobile terminal and the first base station when the mobile terminal is located at a cell boundary of the first base station.

In an embodiment, the procedure of reducing interference in communication between the mobile terminal and the first base station may include a coordinated multiple point transmission and reception technique.

In an embodiment, the procedure of reducing interference in communication between the mobile terminal and the first base station may include Inter-Cell Interference Management (ICIM).

In one embodiment, the mobile communication system may follow the standard of Long Term Evolution (LTE) -Advanced.

According to an embodiment of the present invention, when the mobile terminal is located in a boundary region of a cell of one or more other base stations adjacent to a cell of the first base station and the first base station, the first base station and the one or more other base stations cooperate with each other. A method is provided for communicating with the mobile terminal. A mobile terminal comprising a plurality of antennas, a plurality of base stations, a first base station of the plurality of base stations, the mobile terminal is in charge of the mobile terminal, each of the plurality of base stations includes a plurality of antennas; and can communicate with the plurality of base stations In a mobile communication system including an Evolved Packet Core (EPC) coupled to each other, when the mobile terminal is located in the boundary region of the cell of the first base station and at least one other base station adjacent to the cell of the first base station; 1. A method of causing a base station and one or more other base stations to cooperatively communicate with the mobile terminal, wherein the EPC determines whether the mobile terminal is located at a boundary area between a cell of the first base station and a cell of the one or more other base stations. The EPC, the mobile terminal is the boundary between the cell of the first base station and the cell of the at least one other base station In response to determining that the station is located in a station, instructing the first base station to initiate a coordinated multiple point transmission and reception mode in which the first base station and the one or more other base stations are in communication with the mobile terminal. Making; And the first base station communicates with the mobile terminal in cooperative multipoint transmission / reception mode together with the one or more other base stations, wherein the first base station and the one or more other base stations are multiple-input and multiple-related to the mobile terminal. output).

In an embodiment, the EPC determines whether the mobile terminal is located at a boundary area between a cell of the first base station and a cell of the one or more other base stations, wherein the EPC is determined from the first base station. Receiving a round trip time (RTT) value of the RTT; And determining, by the EPC, whether the mobile terminal is located at a cell boundary of the first base station based on the RTT value.

In the method of the cooperative multipoint transmission / reception technique, the mobile terminal is determined to be located in the cell boundary region of the base station based on the RTT value, thereby increasing the accuracy of the determination of whether the terminal is located in the cell boundary region. Sending / receiving operations can be generated only when actually needed to reduce the load on the network. In addition, it is possible to improve the performance of eliminating interference at the cell boundary area by providing a method in which MIMO is applied to combined transmission among cooperative multi-point transmission and reception techniques.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present invention, when the same numbers indicate the components described in the drawings and the description, generally refer to the same components.

1 is a schematic diagram of an exemplary communications network environment 100 in which the present invention may be practiced. Although FIG. 1 illustrates that the communication network environment 100 includes two base stations 110 and one mobile terminal 130, this is for convenience of explanation and the number and arrangement of actual base stations and terminals may be different. Care must be taken.

As shown in FIG. 1, the network environment 100 may include a base station (eNodeB; 110A, 110B, etc .; referred to as 110 when referring to general matters about the base station), an evolved packet core (EPC) 120, and a mobile terminal 130A. 130B and 130C; if referred to general matters for the mobile terminal, it is referred to as 130). The base station 110 is connected to communicate with the EPC 120.

The communication network environment 100 preferably corresponds to Long Term Evolution (LTE) advanced, but for example, code division multiple access (CDMA), wIDeband code division multiple access (WCDMA), global system for mobile communications (GSM), UMTS ( Conventional mobile networks and next-generation mobile networks, including 2G, 3G, 3.5G, and future 4G, including Universal Mobile Telecommunications System (WiMAX), WorldwIDe Interoperability for Microwave Access (WiMAX), high speed downlink packet access (HSDPA), and future developments It can include all of the networks.

In one embodiment of the present invention, the base station 110 may be a macro base station or a femto-type base station, but is not limited thereto. In one embodiment, the EPC 120 is an access gateway that manages an access service between an IP-based wired network and a wireless access network, a gateway function for routing and forwarding packets, and a connection with an external PDN (System Architecture Evolution Access Gateway; And a mobility management entity (not shown) for performing mobility management and authentication of a terminal, management of bearers, sessions, and non-access stratum (NAS) signaling control, and the like. In one embodiment, the terminal 130 may be provided with a plurality of internal or external antennas to communicate with the base station 110 that is in charge of itself.

In an embodiment of the present invention, the terminal 130 and the base station 110 may communicate by applying a multiple-input and multiple-output (MIMO). MIMO is a technique of increasing the capacity in proportion to the number of antennas used by using a number of antennas in the base station and the terminal. For example, if M is installed in the base station and N in the terminal, the average transmission capacity increases by M × N. Since MIMO is a technique known in the art, a detailed description thereof will be omitted.

An operation according to an embodiment of the present invention will be described. As shown in FIG. 1, the terminal 130A is currently located inside a cell of the base station 110A, and the terminal 130B is located at a cell boundary between the base station 110A and the base station 110B, and the terminal 130C. ) Is located inside the cell of the base station 110B. The terminal 130 and the base station 110 may communicate by applying 2 × 2 MIMO, for example. Where the terminal 130 is currently located, the base station 110A of the jurisdiction may determine by measuring a round trip time (RTT) value. If the terminal at the position of the terminal 130A moves to the position of the terminal 130B, the base station 110A and the base station 110B are regarded as a common virtual cell managing the cell boundary area together with the base station 110A. The base station 110B may communicate with the corresponding terminal 130B by a joint transmission method of the cooperative multipoint transmission / reception schemes, wherein the base station 110A and the base station 110B are together with respect to the terminal 130B. It can operate with 4x4 MIMO. Thereafter, when the terminal returns to the position of the terminal 130A again, the cooperative multipoint transmission / reception mode may be turned off and communication with the base station 110A may be performed again. When the terminal moves to the position of the terminal 130C, the cooperative multipoint The transmit / receive mode may be turned off and handed over to the base station 110C.

2 is a block diagram of the base station 110 and the EPC 120 according to an embodiment of the present invention. It is noted that the components shown in FIG. 2 are exemplary, and each component may be integrated, separated, or omitted according to a design specification, and the connection relationship of each component may also be changed.

As shown in FIG. 2, the base station 110 may include a communication unit 112 capable of transmitting and receiving various data with the EPC 120. The communication unit 112 may be used to transmit the RTT value to the EPC 120, and the base station 110 may transmit a multi-point transmit / receive mode request message and multiple-input and multiple- MIMO to the adjacent base station via the EPC 120. output may be used to send a codebook share request message for transmission preparation. In one embodiment, the communication unit 112 may receive a cooperative multi-point transmit and receive mode start command from the EPC 120.

As shown in FIG. 2, the base station 110 may further include an RTT measurement unit 114. In one embodiment of the present invention, the RTT measurement unit 114 may measure a round trip time (RTT) to the terminal 130 and the base station 110. The method for measuring the RTT is regulated in 3GPP, and can be specifically known from, for example, "Method for Determining the Round Trip Time" of WO2009 / 131507, and the detailed description thereof is omitted.

As shown in FIG. 2, the base station 110 may further include a cooperative communication control unit 116. The cooperative communication control unit 116 may control to transmit data to one terminal simultaneously with an adjacent base station using a cooperative multipoint transmission / reception technique. In one embodiment, in response to receiving the cooperative multipoint transmission / reception mode start command from the EPC 120, the cooperative communication control unit 116 operates the information and / or cooperative multipoint transmission / reception mode of the terminal through the communication unit 112. Send a cooperative multipoint transmit / receive mode request message requesting the request. In addition, in an embodiment, in response to receiving the cooperative multi-point transmission / reception mode request message from another neighboring base station, request to share a codebook for preparing MIMO transmission with the Ack message to the corresponding neighboring base station through the communication unit 112. To send a message. In one embodiment, when the base station 110 communicates with an adjacent base station in a cooperative multipoint transmission / reception mode, the cooperative communication control unit 116 may also simultaneously perform scheduling of communication resources with the adjacent base station.

As shown in FIG. 2, the base station 110 may further include a MIMO control unit 118. The MIMO control unit 118 may allow MIMO to be applied when the base station 110 having the plurality of antennas and the terminal 130 having the plurality of antennas communicate.

As shown in FIG. 2, the EPC 120 may include a communication unit 122 capable of transmitting and receiving data with the base station 110. The communication unit 122 may be used to transmit and receive various types of information including the RTT from the base station 110.

As shown in FIG. 2, the EPC 120 may further include a common cell region determiner 124. The common cell region determination unit 124 may determine whether the terminal 130 is located in the cell boundary region based on the RTT received from the base station 110. In determining the range of the cell boundary region from the base station 110, in one embodiment, it may be set to a specific range when the mobile communication network is installed, and in another embodiment between the base station 110 and the terminal 130 In consideration of the communication situation, the common cell region determiner 124 may dynamically change the range of the cell boundary region. In an embodiment, when determining that the terminal 130 is located in the common cell region, the common cell region determination unit 124 may transmit a command to start the cooperative multipoint transmission / reception mode to the corresponding base station 110.

3 is a logic flow diagram of applying a cooperative multipoint transmission / reception technology mode between two or more base stations 110 and an EPC 120 according to an embodiment of the present invention. It is noted that the steps shown in FIG. 3 are exemplary, and each step may be combined, separated or omitted, and the order of the steps may be changed.

First, in a mobile communication system in which each base station operates with, for example, 2 × 2 MIMO, the base station 110A may periodically measure an RTT value with the terminal 130 (step 300). Thereafter, the measured RTT value may be transmitted to the EPC 120 (step 302). Upon receiving the RTT value, the EPC 120 may determine whether the terminal 130 is located at a cell boundary between the base station 110A and the base station 110B (step 304). If located in the cell boundary region, EPC 120 may instruct base station 110A to initiate a cooperative multipoint transmit / receive mode (step 306). The base station 110A, instructed to initiate the cooperative multipoint transmission / reception mode, may transmit the information of the terminal 130 and / or the cooperative multipoint transmission / reception mode request message to the base station 110B via the EPC 120 ( Step 308). The base station 110B, which has received the information of the terminal 130 and / or the cooperative multipoint transmission / reception mode request message, of the codebook for preparing MIMO transmission with the Ack message to the base station 110A via the EPC 120. A message requesting sharing can be sent (step 310). Thereafter, the base station 110A and the base station 110B may operate in a cooperative multipoint transmission / reception mode to communicate with the terminal 130. In this case, the base station 110A and the base station 110B become a 4 × 4 MIMO, for example. 130) (step 312).

Thereafter, if the terminal 130 leaves the cell boundary area and comes back into the cell of the base station 110A, the base station 110A transmits a cooperative multipoint transmission / reception mode end request message to the base station 110B via the EPC 120. And a response message from the base station 110B to terminate the cooperative multipoint transmission / reception mode and the base station 110A may communicate with the terminal 130 alone (step 314). If the terminal 130 leaves the cell boundary area and enters the cell of the base station 110B, the base station 110B transmits a cooperative multipoint transmission / reception mode end request message to the base station 110A via the EPC 120. In response to the response message from the base station 110B, the cooperative multipoint transmission and reception mode may be terminated, and then a handover procedure may be initiated from the base station 110A to the base station 110B (step 316).

On the other hand, the present invention has been described as an embodiment of applying a cooperative multi-point transmission and reception technology when determining whether the mobile terminal is located in the cell boundary region using the RTT value. However, the present invention is not limited thereto, and a method of determining whether a mobile station is located in a cell boundary region by using an RTT value may include inter-cell interference, for example, an inter-cell interference management (ICIM) technique. It can be applied to other ways to improve the system.

Although the foregoing methods have been described through specific embodiments, the foregoing methods may also be embodied as computer readable codes on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the above-described embodiments can be easily inferred by programmers in the art to which the present invention belongs.

In addition, while the present invention has been described in connection with some embodiments, it is to be understood that various modifications and changes can be made without departing from the spirit and scope of the invention as will be understood by those skilled in the art. You will need to know It is also contemplated that such variations and modifications are within the scope of the claims appended hereto.

1 is a schematic diagram of an exemplary communications network environment 100 in which the present invention may be practiced.

2 is a block diagram of a base station 110 and an EPC 120 according to an embodiment of the present invention.

3 is a logic flow diagram of applying a cooperative multipoint transmission and reception technology mode between two or more base stations 110 and an EPC 120, in accordance with an embodiment of the present invention.

Claims (7)

In a mobile communication system comprising a mobile terminal, a plurality of base stations, a first base station of the plurality of base stations to control the mobile terminal, and an Evolved Packet Core (EPC) coupled to communicate with the plurality of base stations. A method for determining whether the mobile terminal is located in a cell boundary region of a base station, Receiving, by the EPC, a Round Trip Time (RTT) value of the mobile terminal from the first base station; And Determining, by the EPC, whether the mobile terminal is located at a cell boundary of the first base station based on the RTT value / RTI > A mobile terminal comprising a mobile terminal, a plurality of base stations, a first base station of the plurality of base stations having jurisdiction over the mobile terminal, and an Evolved Packet Core (EPC) coupled to communicate with the plurality of base stations. A method of reducing interference in communication between the mobile terminal and the first base station when located in a cell boundary region of the first base station, Receiving, by the EPC, a Round Trip Time (RTT) value of the mobile terminal from the first base station; Determining, by the EPC, whether the mobile terminal is located at a cell boundary of the first base station based on the RTT value; And Initiating, by the EPC, a process of reducing interference in communication between the mobile terminal and the first base station when the mobile terminal is located at a cell boundary of the first base station; / RTI > The method of claim 2, And a procedure for reducing interference in communication between the mobile terminal and the first base station comprises coordinated multiple point transmission and reception techniques. The method of claim 2, The procedure of reducing interference in communication between the mobile terminal and the first base station includes Inter-Cell Interference Management (ICIM). The method of claim 2, And the mobile communication system conforms to the specification of Long Term Evolution (LTE) -Advanced. A mobile terminal comprising a plurality of antennas, a plurality of base stations, wherein a first base station of the plurality of base stations controls the mobile terminal, each of the plurality of base stations including a plurality of antennas, and capable of communicating with the plurality of base stations In a mobile communication system including an Evolved Packet Core (EPC) coupled to, when the mobile terminal is located in the boundary region of the cell of one or more other base stations adjacent to the cell of the first base station and the first base station; A method of causing a base station and the one or more other base stations to cooperate to communicate with the mobile terminal, Determining, by the EPC, whether the mobile terminal is located at a boundary area between a cell of the first base station and a cell of the one or more other base stations; In response to the EPC determining that the mobile terminal is located at a boundary area between a cell of the first base station and a cell of the one or more other base stations, the first base station tells the first base station and the one or more other base stations; Instructing to initiate a coordinated multiple point transmission and reception mode in communication with the mobile terminal; And In response to receiving the command from the EPC, the first base station communicating with the mobile terminal in a cooperative multipoint transmit / receive mode with the one or more other base stations; Wherein the first base station and the one or more other base stations operate with multiple-input and multiple-output (MIMO) for the mobile terminal. The method of claim 6, The step of determining, by the EPC, the mobile terminal is located at a boundary area between a cell of the first base station and a cell of the one or more other base stations, Receiving, by the EPC, a Round Trip Time (RTT) value of the mobile terminal from the first base station; And And determining, by the EPC, whether the mobile terminal is located at a cell boundary region of the first base station based on the RTT value.

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