WO2017051964A1 - Terminal caching method and apparatus using multicast in mobile communication system - Google Patents

Abstract

Disclosed is a terminal caching method using a multicast in a mobile communication system, and particularly, the method comprising the steps of: receiving, from a base station, a group-radio network temporary identifier (G-RNTI), a temporary identifier of a multicast mobile caching (MMC) group comprising a reader terminal and terminals which are interested in content corresponding to a service request transmitted by the reader terminal; receiving, from the base station, the scheduling information transmitted to the reader terminal in response to the service request through an overhearing method by using the G-RNTI; receiving, from the base station, multicast data transmitted to a resource region indicated by the scheduling information, wherein the reader terminal is a terminal, for transmitting the service request first to the base station, among a plurality of terminals which are interested in the content.

Description

Terminal caching method and device using multicast in mobile communication system

The following description relates to a wireless communication system, and more particularly, to a method and apparatus for caching data to a terminal of a user using multicast.

Recently, in the mobile communication network, the load of the base station and the media server increases with the increase of the service request, and the deterioration of the service quality is problematic due to limited network resources. In order to prevent this, various wireless communication technologies have been developed.

Among these, the MBSFN (Multimedia Broadcast and Multicast Service Single Frequency Network) introduces a single frequency network function for the transmission of all base stations in a zone, thereby reducing service interference due to frequency switching during MBMS (Multimedia Broadcast and Multicast Service) transmission. Technology

In addition, caching is to receive the media content from the media server in advance to store the content, if the user requested content is stored immediately to save the content, if not stored so that the network load can be reduced by requesting the content to the media server It is a technique to do.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the general technology as described above, and an object of the present invention is to prevent congestion by providing a service to multiple users simultaneously with one frequency resource.

Another object of the present invention is to increase the frequency resource utilization by the other terminal overhearing and caching the data through the same downlink channel when any terminal receives data from the base station.

Technical objects to be achieved in the present invention are not limited to the above-mentioned matters, and other technical problems which are not mentioned are intended to those skilled in the art from the embodiments of the present invention to be described below. May be considered.

In order to solve the above technical problem, a method of caching multicast data from a base station by a terminal includes: a MMC (Multicast Mobile Caching) consisting of terminals having a content corresponding to a service request transmitted from a base station to a reader terminal and a reader terminal Receiving a Group-Radio Network Temporary Identifier (G-RNTI) which is a temporary identifier of a group, using the G-RNTI, overhearing scheduling information transmitted to a reader terminal in response to a service request from a base station and receiving multicast data transmitted from a base station to a resource region indicated by scheduling information, wherein the reader terminal first sends a service request to a base station among a plurality of terminals having content as an interest. It is a terminal.

The overhearing scheme may be blind detection of the received scheduling information.

The UE may receive the G-RNTI from the base station in a unicast manner through a physical downlink shared channel (PDSCH).

The terminals belonging to the MMC group may be determined by the base station in consideration of the channel state of the reader terminal, and the modulation and coding scheme (MCS) level of the scheduling information may be determined in consideration of the channel state of the reader terminal.

The caching method may further include receiving, from the base station, a paging signal instructing to transition from the idle state to the connected state, and transitioning back to the idle state if the G-RNTI is not received in the connected state.

In order to solve the technical problem, the base station supports the multicast caching of the terminal, MMC (Multicast Mobile Caching) consisting of the terminal having a content of the reader terminal and the content corresponding to the service request sent to the terminal of interest to the terminal Transmitting a group-radio network temporary identifier (G-RNTI), which is a temporary identifier of a group, transmitting scheduling information to a reader terminal, and transmitting multicast data to an MMC group. The terminal is a terminal that first sends a service request to a base station among a plurality of terminals having a content of interest.

The terminal for solving the above technical problem includes a processor operating in connection with a transmitter, a receiver, a transmitter, and a receiver, the processor having a terminal of interest from the base station and the content corresponding to the service request transmitted from the reader terminal Receives a Group-Radio Network Temporary Identifier (G-RNTI), which is a temporary identifier of a multicast mobile caching (MMC) group, and is transmitted to a reader terminal in response to a service request from a base station through the G-RNTI. ) Receiving information in an overhearing manner, and controlling the receiving unit to receive multicast data transmitted from the base station to the resource region indicated by the scheduling information, and the reader terminal to the base station among the plurality of terminals having the content of interest. The terminal that sent the service request first.

The base station for solving the above technical problem includes a processor operating in connection with a transmitter, a receiver, a transmitter, and a receiver, the processor having a reader terminal and a content corresponding to a service request transmitted by the reader terminal as a terminal of interest. Transmit Group-Radio Network Temporary Identifier (G-RNTI), which is a temporary identifier of a Multicast Mobile Caching (MMC) group, and transmits scheduling information to a reader terminal, and transmits multicast data to an MMC group. The transmitter is controlled so that the reader terminal is a terminal that first sends a service request to a base station among a plurality of terminals having a content of interest.

According to embodiments of the present invention, the following effects can be expected.

Firstly, since the user does not use additional frequency resources while viewing the cached data, it is possible to prevent an increase in congestion of the base station.

Second, users can flexibly select multicast target users in real time, thereby increasing frequency resource utilization.

Effects obtained in the embodiments of the present invention are not limited to the above-mentioned effects, and other effects not mentioned above are usually described in the technical field to which the present invention pertains from the description of the embodiments of the present invention. Can be clearly derived and understood by those who have That is, unintended effects of practicing the present invention may also be derived from those skilled in the art from the embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are provided to facilitate understanding of the present invention, and provide embodiments of the present invention together with the detailed description. However, the technical features of the present invention are not limited to the specific drawings, and the features disclosed in the drawings may be combined with each other to constitute new embodiments. Reference numerals in each drawing refer to structural elements.

1 illustrates an example of a multimedia broadcast and multicast service (MBMS) through a single frequency network within a MBSFN service area.

2 illustrates an example of a caching method in a mobile communication network.

3 illustrates a procedure for requesting a service, analyzing a content of a requested service, selecting a terminal of similar interest, selecting an MMC group, and transmitting a G-RNTI according to an embodiment of the present invention.

4 illustrates a process of selecting and paging a terminal from a gateway, an MME, and a base station according to an embodiment of the present invention.

5 is a URI-keyword table and keyword-index table used in content analysis of a requested service according to an embodiment of the present invention.

6 is a terminal-index table used in similar interest terminal selection according to an embodiment of the present invention.

7 illustrates the flow of a keyword matching and paging process according to an embodiment of the present invention.

8 illustrates a flow of a process of transmitting a G-RNTI and a security key to a MMC group by a base station after paging according to an embodiment of the present invention.

9 is a flowchart illustrating a process of receiving downlink resource allocation related scheduling information in an overhearing manner based on a G-RNTI received by an MMC group according to an embodiment of the present invention.

10 is a flowchart illustrating a process of transmitting G-RNTI and security key and transmitting scheduling information and multicast data according to an embodiment of the present invention.

11 is a flowchart illustrating a method for caching multicast data from a base station by a terminal according to an embodiment of the present invention.

12 is a flowchart illustrating a method for a base station to support multicast data caching of a terminal according to an embodiment of the present invention.

13 shows a configuration of a terminal and a base station that can be applied to an embodiment of the present invention.

The terms used in the present invention have been selected as widely used general terms as possible in consideration of the functions in the present invention, but this may vary according to the intention or precedent of the person skilled in the art, the emergence of new technologies and the like. In addition, in certain cases, there is also a term arbitrarily selected by the applicant, in which case the meaning will be described in detail in the description of the invention. Therefore, the terms used in the present invention should be defined based on the meanings of the terms and the contents throughout the present invention, rather than the names of the simple terms.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps which may obscure the gist of the present invention are not described, and procedures or steps that can be understood by those skilled in the art are not described.

Throughout the specification, when a portion is said to "comprising" (or including) a component, this means that it may further include other components, except to exclude other components unless otherwise stated. do. In addition, the “…” described in the specification. Wealth ”,“… The term “unit”, “module”, etc. refer to a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software. Also, “a” or “one”, “the” and similar related terms are not intended to be altered herein in the context of describing the present invention (particularly in the context of the following claims). Unless otherwise indicated or clearly contradicted by context, it may be used in the sense including both the singular and the plural.

In the present specification, embodiments of the present invention have been described based on data transmission / reception relations between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, various operations performed for communication with a mobile station in a network consisting of a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an advanced base station (ABS), or an access point.

In addition, a 'mobile station (MS)' may be a user equipment (UE), a subscriber station (SS), a mobile subscriber station (MSS), a mobile terminal, an advanced mobile station (AMS), a terminal. (Terminal) or a station (STAtion, STA) and the like can be replaced.

Also, the transmitting end refers to a fixed and / or mobile node that provides a data service or a voice service, and the receiving end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in uplink, a mobile station may be a transmitting end and a base station may be a receiving end. Similarly, in downlink, a mobile station may be a receiving end and a base station may be a transmitting end.

In addition, the description that the device communicates with the 'cell' may mean that the device transmits and receives a signal with the base station of the cell. That is, a substantial target for the device to transmit and receive a signal may be a specific base station, but for convenience of description, it may be described as transmitting and receiving a signal with a cell formed by a specific base station. Similarly, the description of 'macro cell' and / or 'small cell' may not only mean specific coverage, but also 'macro base station supporting macro cell' and / or 'small cell supporting small cell', respectively. It may mean 'base station'.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802.xx system, 3GPP system, 3GPP LTE system and 3GPP2 system. That is, obvious steps or portions not described among the embodiments of the present invention may be described with reference to the above documents.

In addition, all terms disclosed in the present document can be described by the above standard document. In particular, embodiments of the present invention may be supported by one or more of the standard documents P802.16e-2004, P802.16e-2005, P802.16.1, P802.16p, and P802.16.1b standard documents of the IEEE 802.16 system. have.

1 illustrates an example of a multimedia broadcast and multicast service (MBMS) through a single frequency network within a MBSFN service area.

MBSFN system 100 includes MBMS service area 102. MBMS service area 102 refers to a group of wireless transmission cells when a particular MBMS service is available and surrounds a number of MBSFN areas 104, 106, 108. MBSFN regions 104, 106, 108 include multiple MBSFN region reserved cells or base stations 110. For example, a particular sport or other program may be broadcast by cells or base stations 110 in MBMS service area 102 at a particular time. Cells or base stations 110 in MBSFN area 106 use the same frequency to perform synchronized transmission. Accordingly, the terminal in the MBSFN region 106 recognizes that one cell transmits MBMS data broadcasted by several cells or base stations 110, even if the terminal moves in the MBSFN region 106. You can get a seamless service.

However, frequency resources for MBSFN are always fixed, which degrades the utilization of frequency resources. For example, if there is no multicast service user in the MBSFN zone, frequency resources are wasted. In addition, the MBSFN system 100 may provide a multicast service only to predetermined users. That is, it does not provide a multicast service by selecting only specific users in real time.

2 illustrates an example of a caching method in a mobile communication network.

In a conventional mobile communication network, as the service request increases, the load of the base station and the media server increases, thereby degrading service quality due to limited network resources. In order to prevent this, a method of providing a user with a cache server at a base station and storing media content transmitted from a media server has been proposed. When the user requests media content (S201), the base station checks whether the corresponding content exists in the cache server. If the requested content does not exist, the base station requests the content from the media server (S202), receives the content response from the media server (S203), stores the content in the cache server, and responds to the content (S204). If the requested content is stored in the cache server in the base station (S201), the content is transmitted to the terminal without the request to the media server (S205).

However, in the case of base station caching having a cache server in the base station as shown in FIG. 2, the service delay time and the load of the server can be reduced as compared to the case where there is no caching, but the congestion of the radio section (terminal to base station) is not reduced. In particular, in a congestion situation, content stored in the cache server in the base station may not be smoothly delivered to the terminal.

Before describing the embodiments of the present invention with reference to the accompanying drawings, a brief description of a terminal caching method using multicast proposed in an embodiment of the present invention. Specific terms used in the embodiments of the present invention are provided to help the understanding of the present invention, and the use of the specific terms may be changed into other forms without departing from the technical spirit of the present invention.

According to an embodiment of the present invention, a plurality of terminals are classified into one reader terminal and other terminals having similar contents interests as those of the reader terminal. The reader terminal is one terminal that first requests a base station for a service of content among a plurality of terminals having similar contents interests. When one reader terminal requests a content service, the server first analyzes content categories and interests of users before the same plurality of service requests are received from other terminals. Subsequently, the base station or the server first transmits the corresponding content to the terminals of the users having similar interests before the user requests, and each terminal stores the received contents. That is, if one of the terminals having similar contents interests requests a service first, the other terminals have a high probability of requesting the same service, and the server transmits the content to each of a plurality of terminals having similar contents interests in advance. Accordingly, network congestion can be lowered by reducing the repeated procedure compared to the case where each terminal requests the same service without caching.

The probability that the content provided through caching becomes the information required by the user is called a fitting rate. Caching has an effect on improving network congestion because a high conformance rate can reduce duplication compared to when each terminal makes a service request. In order to improve the fit ratio, grouping for selecting a terminal having similar interests as the content requested by the reader terminal should be effectively performed. According to an embodiment of the present invention, grouping is performed at the MME and the gateway. The MME performs deep packet inspection (DPI) that inspects the contents of the service request packet and media category keyword classification of the service requested content. The gateway performs a media category keyword derived from the MME based on the content interest data of the pre-written users. By comparison, users who have the same interests as the content requested for the service are selected.

In addition, according to an embodiment of the present invention, even if caching is performed, channel state is also considered to ensure communication quality of the reader terminal. Accordingly, the base station analyzes the channel state of the user terminals selected by the MME and the gateway to select the terminal having a channel state that can ensure the communication quality of the reader terminal.

According to an embodiment of the present invention, the gateway, the MME, and the base station select a terminal having a channel state capable of ensuring the communication quality of the reader terminal with the same content interest as the content requested by the reader terminal. The selected terminal is defined as a multicast mobile caching (MMC) terminal. The leader terminal and the MMC terminal are collectively defined as an MMC group. When the MMC group is determined according to this method, caching is performed for terminals having similar interests, and thus, it can be expected that the fit ratio is improved.

In order to transmit the same content data to the MMC group, it is necessary for the MMC group to share downlink resource allocation related scheduling information. According to an embodiment of the present invention, a method of receiving scheduling information through overhearing is provided so that an MMC group receives scheduling information related to downlink resource allocation. Overhearing refers to a process in which an MMC terminal listens to data transmitted from a base station to a reader terminal. For overhearing, the reader terminal and the MMC terminal must share the same identifier in the network. A temporary identifier shared by an MMC group in order to receive scheduling information related to downlink resource allocation of the same content is defined as a group-radio network temporary identifier (G-RNTI). The MMC group receives the same G-RNTI to the base station, through which the MMC terminal may overhear scheduling information transmitted from the base station to the reader terminal.

In addition, the MMC terminal may receive the same content data transmitted from the base station to the reader terminal through the overhearing scheduling information. Accordingly, the MMC group may store the same content data in each terminal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

3 illustrates a part of a procedure for performing terminal caching in an MBSFN system according to an embodiment of the present invention. 3 illustrates a procedure of requesting a service, analyzing a content of a requested service, selecting a terminal of similar interest, selecting an MMC group, and transmitting a G-RNTI in one embodiment of the present invention. In addition, FIG. 5 to be described together is a URI-keyword table and keyword-index table used in content analysis of a requested service during the procedure shown in FIG. 3. FIG. 6 is a terminal-index table used for terminal selection of similar interest in the procedure shown in FIG. 3. 5 and 6 illustrate the interests of subscription users in advance by the server operator, and is shared between the gateway and the MME.

The reader terminal 10 sends a service request to the base station 20 (S301). As described above, the reader terminal refers to a terminal that first transmits a service request for content to a base station among a plurality of terminals having similar interests. In addition, the service request is a request for transmission of specific media content and includes a Uniform Resource Identifier (URI) of the specific media.

The base station 20 performs the first paging after receiving the service request from the reader terminal 10 (S302). In the first paging, a paging signal is transmitted to terminals having a history of reproducing a URI of content that has received a service request in the past. Terminals in the idle state that receive the paging signal from the base station 20 transition to the connected state.

The base station 20 transmits the service request received from the reader terminal 10 to the gateway 30 (S303). The service request to be delivered is the same as the service request received from the reader terminal, and includes the URI of the content which received the service request.

The gateway 30 performs deep packet inspection (DPI) on the received service request (S304). DPI refers to a method that examines the contents of a packet as well as the source and destination information of the packet. Accordingly, the gateway 30 analyzes the contents of the received service request packet.

The gateway 30 performs media category classification on the contents of the service request packet analyzed through the DPI using the URI-keyword table shown in FIG. 5 (S305). The URI-keyword table of FIG. 5 is a table prepared in advance, and media categories such as sports, science, movies, music, and dramas are matched by keywords for each URI. The gateway 30 derives the media category keyword of the service requested content by looking up the URI of the service request analyzed through the DPI in the URI-keyword table of FIG. 5.

The gateway 30 derives the category index of the service requested content by using the keyword-index table shown in FIG. 5 with respect to the derived media category keyword (S306). The keyword-index table of FIG. 5 is also prepared in advance, and is a table in which indexes of, for example, 0000, 0001, 0010, 0011, 0100, etc. are determined for each category of sports, music, drama, film, science, and the like. The gateway 30 searches the derived media category keyword in the keyword-index table to derive the media category index of the service requested content. The gateway 30 transmits the derived category index to the mobility management entity (MME) 40 together with the paging notification (S306). The paging notification is a signal that the gateway informs the MME to paging the base station after selecting the paging target.

The MME 40 selects the terminal 60 having the media category of the service requested content as the content interest, using the terminal-index table shown in FIG. 6 with respect to the received category index (S307). The terminal-index table of FIG. 6 is prepared in advance, and is a table in which content interests of the user of the terminal are organized by category index for each terminal. The MME 40 finds the received category index in the terminal-index table of FIG. 6 and selects the terminal 60 having the media category of the service requested content as the content interest. For example, if the content requested by the leader terminal is a baseball video, the gateway derives 0000, which is an index of the sports category, and the MME selects a terminal having a 0000 from the terminal-index table, that is, a terminal interested in sports.

The MME 40 transmits an identifier of the selected terminal 60 and a paging command for an idle terminal among the selected terminals 60 to the base station 20 to access the selected terminal 60 (S308). .

The base station 20 transmits a paging signal to the selected terminal 60 in the idle state based on the identifier of the selected terminal 60 received from the MME 40.

Among the selected terminals 60, the selected terminal 60 in the connected state maintains the connected state, and the selected terminal 60 in the idle state transitions to the connected state (S310), so that all the selected terminals 60 are base stations. Is connected to. The selected terminal 60 transmits its channel status report to the base station (S311).

The base station 20 determines the MMC group in consideration of the channel state of the selected terminal 60 according to the received channel state report (S312). The determination of the MMC group in consideration of the channel state is for ensuring the communication quality of the reader terminal 10. For example, the base station 20 may determine the Modulation and Coding Scheme (MCS) level based on the channel state of the reader terminal 10 and thereby guarantee the quality of the reader terminal 10. Preferably, the base station 20 may select a terminal that is equal to or greater than the channel state of the reader terminal 10. Alternatively, the terminal may be selected such that the worse state of the channel state is less than the threshold value than the reader terminal 10. In addition, if retransmission is to be made depending on the situation after the multicast data transmission in order to prevent the degradation of the reader terminal, retransmission of another terminal may be suspended and the retransmission of the reader terminal 10 may be processed first.

The MMC group is a terminal in which terminal caching is performed according to an embodiment of the present invention. The MMC group has a channel category capable of ensuring the communication quality of the reader terminal 10 while having the media category of the terminal selected by the reader terminal 10 and S312, that is, the content requested for service (S301) as the content interest. Excitation terminal (hereinafter, MMC terminal 50).

The base station 20 generates the G-RNTI and transmits the same G-RNTI and security key to the MMC group, that is, the reader terminal 10 and the MMC terminal 50. The G-RNTI is a temporary identifier shared by the MMC group in order to receive scheduling information related to downlink resource allocation of the same content. By receiving the same G-RNTI, the MMC groups share the same identifier. The base station 20 transmits the G-RNTI and the security key to the MMC group in a unicast manner through a physical downlink shared channel (PDSCH).

The base station 20 transmits downlink resource allocation related scheduling information to the reader terminal 10. The MMC terminal receives the downlink resource allocation related scheduling information transmitted to the reader terminal in an overhearing manner (S315). The overhearing is performed through blind detection of the received scheduling information. The blind detection refers to a process of finding out what the current modulation scheme is from the received signal. The MMC terminal 50 determines a modulation scheme through blind detection, and then demodulates the received scheduling signal through an equalization process.

4 illustrates a part of a procedure for performing terminal caching in an MBSFN system according to an embodiment of the present invention. 4 illustrates a process of selecting and paging a terminal from a gateway, an MME, and a base station in detail according to an embodiment of the present invention.

The service request S301 of the reader terminal 10 includes a URI of a specific media. For example, the URI "http://www.youtube.com/watch?v=rf3d5Y8M4sI" is included in the service request. The base station 20 transfers the service request received from the reader terminal 10 to the gateway 30 as it is. The URI of the specific media is also transmitted to the gateway 30 through the base station 20.

The gateway 30 analyzes the contents of the data packet received through the DPI and derives the URI of the specific media. The gateway 30 derives a media category keyword matching the URI of the specific media derived from the DPI result using the URI-keyword table of FIG. 5 previously prepared. For example, the gateway 30 derives a media category keyword of “sport” as a video of a sports field as a URI of “http://www.youtube.com/watch?v=rf3d5Y8M4sI” in FIG. 5. In addition, the gateway 30 derives the media category index through the keyword index table of FIG. 5 previously prepared. For example, the gateway 30 derives a keyword index of '0000' for the keyword 'sports' in FIG. 5. The gateway 30 transmits the index derived together with the paging notification to the MME (S306).

The MME 40 selects the terminal 60 having the same interest as the content of the service request by using the terminal-index table of FIG. 6 prepared in advance based on the received index. The terminal-index table of FIG. 6 is a table in which content interest for each user terminal is pre-filled with an index. The MME 40 may select the terminal 60 that is interested in the media category of the service requested content through the terminal-index table of FIG. 6. For example, if the media category index of the service-requested content is '0000' indicating sports, and terminal 1 and terminal 2 have '0000' in the terminal-index table, the terminal 1 and terminal 2 are interested in sports. As a terminal, it is a terminal which can raise the fitting ratio of MMC group selection. Therefore, the MME 40 selects the terminal 1 and the terminal 2 and transmits a paging command for the terminal in the idle state of the base station 20 (S308).

The base station 20 transmits a paging signal only to the terminal 1 (51) and the terminal 2 (52) that has received the paging command among the terminal 70 in the cell (S309). Accordingly, only the terminal 1 51 and the terminal 2 52 of the terminal 70 in the cell transition to the base station.

7 illustrates a part of a procedure for performing terminal caching in an MBSFN system according to an embodiment of the present invention. 7 illustrates the flow of keyword matching and paging in detail according to an embodiment of the present invention.

The service request is transmitted from the reader terminal 10 to the base station 20 (S301). The base station 20 transmits the received service request to the gateway 30. The gateway 30 performs DPI on the received service request packet (S304).

The gateway 30 derives the category keyword of the content and the index of the keyword by using the URI derived from the DPI result using the URI-keyword table and keyword-index table of FIG. 5. The gateway 30 transmits a paging notification to the MME 40 together with the index of the keyword (S306).

The MME 40 selects the terminal 60 having the same interest as the content of the service request based on the received keyword index of FIG. 6. The MME 40 transmits a paging command for the terminal in the idle state, together with the paging information (S308).

The base station 20 transmits a paging signal to the terminal 1 51 and the terminal 2 52 which are in an idle state among the terminal 60 having the same interest as the content of the service request based on the paging command and the paging information received by the MME. send.

According to this procedure, when one of the similar content use groups requests the service of the content at a specific place and at a specific time, the base station wakes up all the groups with similar interests once connected. Subsequently, the base station determines an MMC group for a terminal capable of smooth communication among them according to channel conditions, and distributes the corresponding content to increase the suitability. Statistically, users with similar interests use or do not use the communication network by requesting or not requesting services at similar times with respect to the content for that interest. Therefore, it is difficult for the user to use the service smoothly at the time of traffic congestion, and the operator has a problem of spending network operation cost at the time of the busy traffic. Accordingly, in order to reduce the burden on both network operators and users, it is necessary to provide services based on the prediction of appropriate fit ratio. In order to increase the fit rate, effective grouping to select an MMC group is required. The criteria for grouping are interests and channel conditions, and the gateway 30 and the MME 40 select a terminal based on the interests. Thereafter, the base station 20 selects an MMC group, that is, a terminal to be finally cached, based on the channel state among the selected terminals. The terminal, which is not selected as the MMC group among the terminals awakened in the connected state according to the transmission of the paging signal of the base station 20, returns to the idle state again without receiving the G-RNTI and the security key.

8 illustrates a part of a procedure for performing terminal caching in an MBSFN system according to an embodiment of the present invention. 8 illustrates a flow of a process of transmitting a G-RNTI and a security key to a MMC group by a base station after paging according to an embodiment of the present invention.

After determining the MCS group (S312), the base station 20 transmits the G-RNTI and the security key to the MCS group (S313). Transmission of the G-RNTI and the security key is performed through the PDSCH in a unicast manner to each reader terminal 10 and the MCS terminal 50.

The G-RNTI and the security key are transmitted to each of the terminals 10 and 51 in unicast through a physical downlink shared channel (PDSCH). The G-RNTI is delivered through PDSCH / Downlink Shared Channel (PDSCH) / Common Control Channel (CCCH) / Signaling Radio Bearer 0 (SRB0) in an RRC connection setup step. The G-RNTI may be configured in a bit string size (16 bits), but is not limited to such an implementation form and may be implemented in various forms and number of bits. The terminal that has not received the G-RNTI and the security key is not selected as an MMC group and returns to an idle state again. For example, in FIG. 8, terminal 2 52 is a terminal that is not selected as an MMC group. The base station 20 does not transmit the G-RNTI and the security key to the terminal 2 (52).

9 illustrates a part of a procedure for performing UE caching in an MBSFN system according to an embodiment of the present invention. 9 is a flowchart illustrating a process of receiving an overhearing method of downlink resource allocation related scheduling information based on a G-RNTI received by an MMC group according to an embodiment of the present invention.

The base station 20 transmits downlink resource allocation related scheduling information to the reader terminal 10. The MMC terminal 50 receives the downlink resource allocation related scheduling information transmitted to the reader terminal 10 in an overhearing manner (S315). Overhearing refers to a process in which the MMC terminal 50 overhears the data transmitted from the base station 20 to the reader terminal 10. Specifically, overhearing is a process in which the MMC terminal 50 detects the G-RNTI, which is a temporary identifier for sharing scheduling information specifically transmitted to the reader terminal 10. The MMC terminal 50 receives the same G-RNTI as the reader terminal 10 from the base station 20, through which the MMC terminal 50 may overhear scheduling information transmitted from the base station to the reader terminal 10. have. In an embodiment of the present invention, the overhearing is performed through blind detection of the received scheduling information.

By receiving the scheduling information, the MMC terminal 50 obtains allocated resource information of the same multicast data as that of the reader terminal 10. The MMC terminal 50 receives the multicast data transmitted to the resource region indicated by the scheduling information in the same manner as the reader terminal 10 based on the received scheduling information (S317). Accordingly, the MMC terminal 50 may store data of the same content as the content requested by the reader terminal 10 in the terminal. That is, the MMC terminal 50 does not directly request content, but receives and stores data according to a request of the reader terminal 10 having similar interests. Thereafter, the MMC terminal may perform a caching by responding to a content when the stored media content corresponds to the requested media at the request of the user and requesting a service from the base station when the requested media is not stored.

FIG. 10 illustrates a part of a procedure for performing UE caching in an MBSFN system according to an embodiment of the present invention. FIG. 10 is a flowchart illustrating a transmission process of a G-RNTI and a security key and transmission of scheduling information and multicast data according to an embodiment of the present invention.

The terminal 60 having the media category of the service requested content as the content interest is transitioned to the connected state by the paging signal transmission of the base station 20 (S310). The base station 20 determines the MMC terminal 50 to belong to the MMC group based on the channel state among the terminal 60 in the connected state. For example, in FIG. 10, terminal 1 51, which is a terminal capable of ensuring the communication quality of the reader terminal 10, is determined as an MMC group, but terminal 2, which is a terminal that cannot guarantee the communication quality of the reader terminal 10. 52 cannot be determined as an MMC group. Accordingly, the terminal 2 52 that is not determined as the MMC group is switched to the idle state again.

The base station 20 transmits a G-RNTI and a security key to the reader terminal 10 and the MMC terminal 50, for example, the terminal 1 51 in FIG. 10. The reader terminal 10 and the MMC terminal 50 receive scheduling information through the G-RNTI. The reception of the scheduling information is performed in such a manner that the MMC terminal 50 overhears the scheduling information S314 transmitted to the reader terminal 10 (S315).

The reader terminal 10 and the MMC terminal 51 obtain the same downlink resource allocation information related scheduling information, and based on this, receive the same multicast data transmitted to the resource region indicated by the scheduling information (S316, S317). ).

When re-receipt of the same data is required due to incomplete reception of data, data retransmission may be performed (S318 and S319). Data retransmission is performed in the same way as data transmission. However, the base station 20 may suspend the retransmission of the MMC terminal 50 and may preferentially process the retransmission of the reader terminal 10 in order to prevent communication quality degradation of the reader terminal 10.

11 is a flowchart illustrating a method of caching multicast data of an MMC terminal 50 according to an embodiment of the present invention. 11 illustrates the embodiment described above according to a time series flow. Therefore, even if not explicitly shown or described in Figure 11 it can be easily seen that the above-described proposals can be applied to the same or similar.

Multicast data reception of the MMC terminal 50 starts from the selection process to the MMC group.

The terminal is selected by the terminal 60 having the media category of the content requested by the MME 40 as the content interest, and receives a paging signal from the base station 20 (S1110), and transitions from the idle state to the connected state. do.

The terminal in the connected state transmits each channel status report to the base station 20 (S1120). The terminal is determined as the MMC terminal 50 belonging to the MMC group when the communication quality of the reader terminal 10 can be guaranteed based on the channel status report from the base station. The terminal determined as the MMC terminal 50 receives the G-RNTI and the security key from the base station 20 (S1130). Since the terminal that has not received the G-RNTI and the security key from the base station 20 is not determined by the MMC terminal 50, the terminal transitions to the idle state.

Upon receiving the G-RNTI and the security key, the MMC terminal 50 receives the downlink resource allocation related scheduling information received by the reader terminal 10 from the base station in an overhearing manner (S1140). The overhearing of the MMC terminal 50 is performed through blind detection of the received scheduling information. The MMC terminal 50 receives the same downlink resource allocation related scheduling information as the leader terminal 10 due to over-earing.

The MMC terminal 50 receives data transmitted from the base station to the resource region indicated by the scheduling information in the same manner as the reader terminal 10 based on the scheduling information (S1150). That is, the MMC terminal 50 receives the media content data requested by the reader terminal 10. The MMC terminal may perform caching by storing the received media content data and responding to the content when the user requests it.

12 is a flowchart illustrating a method in which a base station supports multicast data caching of an MMC terminal 50 according to an embodiment of the present invention. 12 illustrates an embodiment described above according to a time series flow. Accordingly, similarly to the case of FIG. 11, even if not explicitly illustrated or described in FIG. 12, it is easily understood that the above-described proposals may be applied identically or similarly.

The base station 20 transmits a paging signal to the terminal selected by the terminal 60 having the media category of the content requested by the MME 40 as the content interest (S1210). The terminal receiving the paging signal from the base station 20 transitions from the idle state to the connected state.

The terminal that receives the paging signal from the base station 20 and transitions to the connected state transmits channel state information to the base station 20. The base station 20 receives channel state information from the terminal (S1220). The base station 20 determines the terminal capable of guaranteeing the communication quality of the reader terminal 10 as the MMC terminal 50 belonging to the MMC group based on the received channel state report (S1230).

The base station 20 transmits the G-RNTI and the security key to the MMC group, that is, the reader terminal 10 and the MMC terminal 50. The base station 20 transmits the G-RNTI and the security key to each reader terminal 10 and the MMC terminal 50 in a unicast manner through a physical downlink shared channel (PDSCH).

The base station 20 transmits multicast resource related scheduling information to the reader terminal 10 (S1250). In this case, the scheduling information 3 is transmitted in a form in which scheduling information is transmitted to the reader terminal 10, but the MMC terminals 50 overhear this scheduling information, and as a result, the reader terminal 10 and the MMC terminal ( 50), the scheduling information is multicasted. Overhearing of the MMC terminal 50 is performed through blind detection of the received scheduling information. The MMC terminal 50 receives the same downlink resource allocation related scheduling information as the leader terminal 10 due to over-earing.

After transmission of the scheduling information, the base station 20 transmits multicast data to the MMC groups 10 and 50 (S1260). Since the same scheduling information is transmitted to each of the MMC groups through overhearing, the same data is also transmitted to each terminal in the multicast data.

13 is a diagram illustrating a configuration of a terminal and a base station according to an embodiment of the present invention. In FIG. 13, the terminal 1300 and the base station 1400 may include radio frequency (RF) units 1310 and 1410, processors 1320 and 1420, and memories 1330 and 1430, respectively. Although FIG. 13 illustrates only a 1: 1 communication environment between the terminal 1300 and the base station 140, a communication environment may also be established between a plurality of terminals and a plurality of base stations.

Each RF unit 1310, 1410 may include a transmitter 1312, 1412 and a receiver 1314, 1414, respectively. The transmitting unit 1312 and the receiving unit 1314 of the terminal 1300 are configured to transmit and receive signals with the base station 1400 and other terminals, and the processor 1320 is functionally functional with the transmitting unit 1312 and the receiving unit 1314. In connection, the transmitter 1312 and the receiver 1314 may be configured to control a process of transmitting and receiving signals with other devices. In addition, the processor 1320 performs various processes on the signal to be transmitted and then transmits the signal to the transmitter 1312, and performs the process on the signal received by the receiver 1314.

If necessary, the processor 1320 may store the information included in the exchanged message in the memory 1330. With such a structure, the terminal 1300 can perform the method of various embodiments of the present invention described above.

The transmitting unit 1412 and the receiving unit 1414 of the base station 1400 is configured to transmit and receive signals with other base stations and terminals, and the processor 1420 is functionally connected to the transmitting unit 1412 and the receiving unit 1414 and The 1414 and the receiver 1414 may be configured to control a process of transmitting and receiving a signal with other devices. In addition, the processor 1420 may perform various processing on a signal to be transmitted, transmit the same to the transmitter 1412, and may process a signal received by the receiver 1414. If necessary, the processor 1420 may store information included in the exchanged message in the memory 1430. With this structure, the base station 1400 can perform the method of the various embodiments described above.

The processors 1320 and 1420 of the terminal 1300 and the base station 1400 respectively instruct (eg, control, adjust, manage, and the like) operations at the terminal 1300 and the base station 1400, respectively. Respective processors 1320 and 1420 may be connected to memories 1330 and 1430 that store program codes and data. The memories 1330 and 1430 are connected to the processors 1320 and 1420 to store operating systems, applications, and general files.

The processors 1320 and 1420 of the present invention may also be referred to as a controller, a microcontroller, a microprocessor, a microcomputer, or the like. Meanwhile, the processors 1320 and 1420 may be implemented by hardware or firmware, software, or a combination thereof.

When implementing embodiments of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) configured to perform the present invention. Field programmable gate arrays (FPGAs) may be provided in the processors 1320 and 1420.

Meanwhile, the above-described method may be written as a program executable on a computer, and may be implemented in a general-purpose digital computer which operates the program using a computer readable medium. In addition, the structure of the data used in the above-described method can be recorded on the computer-readable medium through various means. Program storage devices that may be used to describe storage devices that include executable computer code for performing the various methods of the present invention should not be understood to include transient objects, such as carrier waves or signals. do. The computer readable medium includes a storage medium such as a magnetic storage medium (eg, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (eg, a CD-ROM, a DVD, etc.).

It will be understood by those skilled in the art that embodiments of the present invention can be implemented in a modified form without departing from the essential characteristics of the above description. Therefore, the disclosed methods should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the detailed description of the invention, and all differences within the equivalent scope should be construed as being included in the scope of the present invention.

The terminal caching method using multicast as described above has been described with reference to an example applied to 3GPP LTE / LTE-A system, but it is possible to apply to various wireless communication systems including IEEE 802.16 in addition to 3GPP LTE / LTE-A. Do.

Claims (10)

1. A method for caching multicast data from a base station by a terminal in a wireless communication system,

   Group-Radio Network Temporary Identifier (G-RNTI), which is a temporary identifier of a multicast mobile caching (MMC) group, which is composed of a terminal having a content of a reader terminal and a content corresponding to a service request transmitted by the reader terminal as an interest. Receiving;

   Using the G-RNTI, receiving scheduling information transmitted from a base station to a reader terminal in response to the service request in an overhearing manner;

   Receiving multicast data transmitted from the base station to a resource region indicated by the scheduling information,

   The reader terminal is a terminal that first sends the service request to the base station of the plurality of terminals having the content of interest,

   How to cache multicast data.
2. The method of claim 1,

   The overhearing method may blind detection the received scheduling information.

   How to cache multicast data.
3. The method of claim 1,

   The terminal receives the G-RNTI from the base station in a unicast scheme through a physical downlink shared channel (PDSCH),

   How to cache multicast data.
4. The method of claim 1,

   The terminals belonging to the MMC group are selected by the base station in consideration of the channel state of the reader terminal.

   Modulation and Coding Scheme (MCS) level of the scheduling information, characterized in that determined in consideration of the channel state of the reader terminal,

   How to cache multicast data.
5. The method of claim 1,

   The caching method,

   Receiving a paging signal from the base station instructing to transition from an idle state to a connected state; And

   If the G-RNTI is not received in the connected state, transitioning to an idle state again, further comprising:

   How to cache multicast data.
6. A method for supporting a multicast data caching of a terminal by a base station in a wireless communication system,

   Group-Radio Network Temporary Identifier (G-RNTI), which is a temporary identifier of a multicast mobile caching (MMC) group, consisting of a reader terminal and terminals having a content corresponding to a service request transmitted by the reader terminal as a concern Transmitting;

   Transmitting scheduling information to the reader terminal;

   Transmitting multicast data to the MMC group,

   The reader terminal is a terminal that first sends the service request to the base station of the plurality of terminals having the content of interest,

   How to apply.
7. The method of claim 5,

   The base station transmits the G-RNTI to the terminal through a unicast scheme through a physical downlink shared channel (PDSCH),

   How to apply.
8. The method of claim 5,

   Terminals belonging to the MMC group are determined by the base station in consideration of the channel state of the reader terminal,

   Modulation and Coding Scheme (MCS) level of the scheduling information, characterized in that determined in consideration of the channel state of the reader terminal,

   How to apply.
9. A terminal for caching multicast data from a base station in a wireless communication system,

   A transmitter;

   Receiver; And

   A processor operating in connection with the transmitter and the receiver,

   The processor is a G-RNTI (Group-Radio Network), which is a temporary identifier of a multicast mobile caching (MMC) group, which is composed of a terminal having interest as a reader terminal and a content corresponding to a service request transmitted by the reader terminal from the base station. Receives a temporary identifier (ID), receives the scheduling information transmitted to the reader terminal in response to the service request from the base station through the G-RNTI in an overhearing manner, and the scheduling information from the base station Control the receiving unit to receive the multicast data transmitted to the indicating resource region,

   The reader terminal is a terminal that first sends the service request to the base station of the plurality of terminals having the content of interest,

   Terminal.
10. A base station supporting multicast data caching of a terminal in a wireless communication system,

    A transmitter;

    Receiver; And

    A processor operating in connection with the transmitter and the receiver,

    The processor is a G-RNTI (Group-Radio Network) which is a temporary identifier of a multicast mobile caching (MMC) group, which is composed of a reader terminal and terminals having an interest in a content corresponding to a service request transmitted by the reader terminal. Transmits a temporary identifier, transmits scheduling information to a reader terminal, controls the transmitter to transmit multicast data to the MMC group,

    The reader terminal is a terminal that first sends the service request to the base station of the plurality of terminals having the content of interest,

    Base station.

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