KR101268580B1 - Method and apparatus for providing multimedia broadcast multicast service - Google Patents

Abstract

The present invention relates to a method and apparatus for providing a multimedia broadcast multicast service.

According to the present invention, the method for providing a multimedia broadcast multicast service (MBMS) by the base station according to an embodiment of the present invention, to determine the number of terminals receiving the multimedia broadcast multicast service, A single cell or multi-cell transmission scheme is determined by comparing the number with a predetermined single cell and multi-cell threshold.

MBMS, MBS, Feedback, Announcement, Multiplexing

Description

METHOD AND APPARATUS FOR PROVIDING MULTIMEDIA BROADCAST MULTICAST SERVICE}

The present invention relates to a method and apparatus for providing a multimedia broadcast multicast service. In particular, the present invention relates to a method and apparatus for providing multimedia broadcast multicast service transmission, feedback, notification and multiplexing.

The present invention is derived from the research conducted as part of the Ministry of Knowledge Economy's information and communication standard development project [Task Management Number: 2008-P1-01-06K51, Task name: WiBro Evol, Research on standardization technology].

The data transmission service in the conventional mobile communication system may be divided into a multimedia broadcast multicast service and a unicast service.

In the case of a unicast service, each terminal performs a service using different radio resources, and in the case of a broadcast multicast service, a service having higher efficiency of radio resources is performed by using the same radio resource for multiple terminals. Do this. Here, the broadcast multicast service is for called MBMS (Multimedia Broadcast Multicast Service) and, IEEE 802.16 MBS (Multicast Broadcast Service) referred to the case of ^{3GPP (3 rd Generation Partnership Project)} .

In general, various signals may occur due to fading and interference signals of a wireless channel. In the mobile communication system, an error correcting method is largely a hybrid automatic repeat request (ARQ) method, an error correcting code (forward error correction) method, a hybrid automatic repeat request (Retransmission method) and an error correction code method. HARQ) method may be mentioned.

Here, the hybrid retransmission (HARQ) scheme is to improve the error correction capability by operating the retransmission and the error correction code of the physical layer. That is, the hybrid retransmission (HARQ) scheme does not discard the previous data packet in which an error occurs, and inputs an error correction decoder to decode the next retransmitted data packet so that the error correction capability is improved. In general, since an error occurs only in a part of a packet, the error correction capability is improved by inputting to the decoder without discarding the packet in which the error occurs.

On the other hand, in order to use the error correction code of the physical layer, the amount of data to be stored is greatly increased. In order to reduce the amount of data to be stored, the hybrid retransmission (HARQ) method has a very fast error of data through the feedback channel. Report the occurrence and receive retransmissions quickly.

However, the conventional 3GPP WCDMA MBMS service does not perform a HARQ scheme, and uses a HARQ scheme for allocating a unique feedback channel for each UE when the MBMS service is transmitted only to a single cell in a Long Term Evolution (LTE) system. It was.

Therefore, in the case of LTE MBMS single cell service, the feedback channel performs feedback both when an error occurs and when it does not occur, so the amount of feedback increases, so that a limited number of feedback channels cannot be allocated to many terminals. have.

In the case of the IEEE 802.16e MBS service, a method of performing retransmission in the physical layer without using a feedback allocation resource is used. There is a problem in that unnecessary retransmission occurs even when a terminal having an error does not exist by performing retransmission for all data without using a feedback channel.

Accordingly, an object of the present invention is to provide a service providing method and apparatus for setting a transmission scheme to maximize radio resource efficiency according to the number of terminals when performing a broadcast multicast service.

In addition, the present invention provides a method and apparatus for providing a multimedia broadcast multicast service which prevents unnecessary data transmission and retransmission by inspecting a case in which a terminal to be received after service start does not exist and controls the amount of interference due to feedback overhead. It aims to do it.

In order to solve the above technical problem, a base station according to an embodiment of the present invention to provide a multimedia broadcast multicast service (MBMS),

a) determining the number of terminals receiving the multimedia broadcast multicast service; And b) determining a single cell or multi-cell transmission scheme by comparing the number of terminals identified in step a) with a predetermined single cell and multi-cell threshold.

Here, the step a) may include: requesting the terminal to receive a multimedia broadcast multicast service by the terminal through a broadcast channel; And receiving a reception intention for each multimedia broadcast multicast service through a feedback channel assigned to the terminal.

And, step b), if the number of the terminal is smaller than the threshold is determined by the single cell transmission method; And allocating a common feedback channel for the single cell via a control channel.

On the other hand, step b) includes the step of determining the multi-cell transmission method when the number of terminals is larger than the threshold; And allocating a common feedback channel for each cell if the number of terminals of each cell does not exceed a frequency of use of a predetermined feedback channel.

On the other hand, the apparatus for providing multimedia broadcast multicast service according to an embodiment of the present invention,

A communication unit for determining the number of terminals receiving the multimedia broadcast multicast service; And a controller for determining a single cell or multi-cell transmission scheme by comparing the identified number of terminals with a predetermined single cell and a multi-cell threshold.

Here, the communication unit requests a reception doctor for each multimedia broadcast multicast service through a broadcast channel to the terminal, and receives the reception doctor through a feedback channel assigned to the terminal.

The control unit may include a control channel for notifying at least one of an identifier for each multimedia broadcast multicast service, data transmission time information, and location information of a radio resource, a notification channel for grasping the number of terminals or notifying a change of a specific notification; and At least one of feedback channels for receiving feedback from the terminal is used.

If the number of terminals is smaller than the threshold, the controller determines the single cell transmission scheme or, if the number of terminals is larger than the threshold, determines the multi-cell transmission scheme.

The controller retransmits the data a predetermined number of times without allocating the common feedback channel when the number of terminals of each cell exceeds the frequency of use of the feedback channel.

According to the above configuration, when transmitting a plurality of multimedia broadcast multicast services in a cell in a multi-cell transmission that does not perform common feedback, a plurality of services may be transmitted at different traffic sizes according to time to prevent unnecessary retransmissions. Has

In addition, according to an embodiment of the present invention, since the HARQ scheme with feedback is used in the multimedia broadcast multicast service, the L1 / L2 control channel may be used for retransmission and notification, and may be quickly processed at the physical layer of the terminal. There is an effect that the terminal in the state can receive the retransmitted data without transmitting the feedback.

In addition, the present invention can prevent the unnecessary data transmission and retransmission by inspecting the case that the terminal receiving the service does not exist after starting the MBMS service, and can expect the effect of controlling the amount of interference due to feedback overhead Can be.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, and the like described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. Can be.

In the present specification, a terminal includes a mobile station (MS), a terminal, a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), and a user device. May refer to a user equipment (UE), an access terminal (AT), and the like, and may include all or some functions of a mobile terminal, a subscriber station, a portable subscriber station, a user device, and the like.

In this specification, a base station (BS) is an access point (AP), a radio access station (RAS), a node B, a base transceiver station (BTS) Mobile Multihop Relay) -BS, and may include all or some of the functions of an access point, a radio access station, a Node B, a base transceiver station, and an MMR-BS.

Now, a method and apparatus for providing a multimedia broadcast multicast service according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a network for providing an MBMS service according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the network for providing an MBMS service according to an embodiment of the present invention is connected to an MBMS service center (BM-SC) 100 that provides an MBMS service (BM-SC) 100 and a BM-SC. It includes a gateway 200, a base station 300, and a terminal 10 supporting the cast service.

In general, the MBMS service center BM-SC 100 is equipped with a real-time processing protocol RTP (Real Time Protocol) and User Datagram Protocol (UDP), RTP includes an error correction encoder, UDP UDP checksum generator is included.

The air interface protocol of the base station 300 and the terminal 10 is horizontally composed of a physical layer, a data link layer, and a network layer, and vertically transmits data information. It is divided into a user plane (User Plane) and a control plane (Control Plane) for transmitting a control signal (Signaling). In addition, the protocol layers are based on the lower three layers of the Open System Interconnection (OSI) reference model, which is widely known in communication systems, and includes L1 (first layer), L2 (second layer), and L3 (third layer). Hierarchical).

The physical layer as the first layer provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to the upper medium access control (MAC) layer through a transport channel. Data is transferred between the medium access control layer and the physical layer through this transport channel.

The MAC layer of the second layer provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission and performs segmentation and concatenation (RDU) service data unit (SDU) function from the upper layer. Can be.

The radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane, and the configuration, re-configuration, release and release of radio bearers are performed. It is in charge of the control of logical channels, transport channels and physical channels.

The base station 300 includes a communication unit for determining the number of terminals 10 receiving the MBMS service and a controller for determining a single cell or multi-cell transmission scheme according to the identified number of terminals 10.

The communication unit informs the broadcast channel of the system of the control channel of the multimedia broadcast multicast service in order to count the number of terminals 10 before starting the service. The communication unit queries the terminal 10 for the service receiving intention through the control channel and determines the number of the terminals 10 in response. At this time, the control channel includes at least one of identifier information for each service, radio resource location of the feedback channel, and information on the transmission channel information. Here, the announcement channel serves to grasp the number of the terminals 10 or to notify a change of a specific announcement, and the feedback channel refers to a channel for receiving feedback from the terminal 10.

The control unit controls the overall operation and function of the base station 300, and determines a single cell or multi-cell transmission scheme according to the number of terminals 10 identified by the communication unit. In addition, if the expected frequency of feedback use according to the number of terminals 10 for each cell exceeds a preset threshold, all cells of the multi-cell do not perform the feedback, and if the threshold is not exceeded, the control is performed to perform the feedback.

In the multi-cell transmission scheme, the control unit allocates a common feedback channel for each cell so that retransmission is performed for each cell. When the feedback channel is not allocated, the control unit simultaneously performs retransmission.

When the terminal 10 intends to receive the service, the terminal 10 receives the control channel by acquiring the location information of the multimedia broadcast multicast service control channel from the broadcast channel of the system. Then, the response is performed with the feedback channel assigned to the notification channel inquiring the intention of receiving the service.

The base station 300 and the network side may repeatedly perform such notification to determine the number of the terminals 10 and determine the service transmission scheme in consideration of the number.

According to the service reception response, the MBMS service data passes through the gateway 200, and then is transmitted to the terminal 10 via the base station 300. The physical layer of the terminal 10 receives data passing through a wireless channel. After decoding is performed, a cyclic redundancy check (CRC) error is checked.

That is, after performing channel decoding, the physical layer of the terminal 10 performs a CRC check to determine whether an error occurs in the data packet, and transmits the CRC check result to the base station 300.

According to an embodiment of the present invention, a part of the L1 / L2 control channel is used as the multimedia broadcast multicast service announcement channel. Here, the notification may be used when a service is started, when a specific content of the control channel of the service is changed or when a response is requested to confirm the existence of the terminal receiving the service.

In more detail, in order to reduce power consumption in the mobile communication system, the terminal 10 operates by dividing the state of the terminal 10 into a connected state and an IDLE state.

When the terminal 10 is in the connected state, for example, it is connected to the base station 300 to receive unicast service, and when the terminal 10 is in the IDLE state, it does not receive unicast service. Is a small state that periodically checks system information and paging reception.

On the other hand, in the case of a multimedia broadcast multicast service, the terminal 10 may receive a service in both a connection state and an IDLE state. Therefore, in the case of broadcast multicast service, the control channel and data transmission are performed in such a manner as to reduce power consumption of the terminal 10 in the IDLE state. Therefore, the terminal 10 usually stays in the IDLE state most of the time.

In the case of a unicast service, the base station 300 transmits an L1 / L2 control channel including identifier information of the terminal 10 to the terminals 10. Then, the terminal 10 reads the control channel to check the service opportunity of the terminal 10 and transmits and receives data. In addition, since the L1 / L2 control channel transmits paging information to the terminal 10 in the IDLE state, the terminal 10 in the IDLE state periodically receives the L1 / L2 control information. This L1 / L2 control channel has an advantage that can be processed quickly in the physical layer of the terminal 10.

However, in the conventional 3GPP WCDMA and IEEE 802.16e multimedia broadcast multicast service, the control information is transmitted through the multimedia broadcast multicast control channel, not the L1 / L2 control channel received by the physical layer. Accordingly, the terminal 10 obtains data scheduling time information through the multimedia broadcast multicast control channel.

At this time, the multimedia broadcast multicast control channel is a channel that does not process quickly in the physical layer and processes a signal in a protocol higher than the MAC layer. That is, the conventional method did not accommodate the HARQ method with feedback, so that the fast processing of the physical layer was unnecessary.

However, according to an embodiment of the present invention, since the HARQ scheme with feedback is used, the L1 / L2 control channel may be used for retransmission. In addition, the L1 / L2 control channel is used for known purposes.

Meanwhile, the multimedia broadcast multicast transmission method according to the number of terminals according to an embodiment of the present invention will be described with reference to FIGS. 2 to 5.

2 is a diagram illustrating a multimedia broadcast multicast transmission method for each case according to the number of terminals according to an embodiment of the present invention.

Referring to FIG. 2, Case1 represents a single cell, Case3 represents a multi-cell transmission in which feedback is performed, and Case2 and Case3 represent a multicell transmission in which no feedback is performed.

Here, "A" and "S" mean the number of terminals 10 in the identified cell, and the number "A" of terminals 10 is smaller than a predetermined single cell and multi-cell threshold. The number "S" of the terminal 10 means a number greater than a predetermined single cell and multi-cell threshold.

First, FIG. 3 is a flowchart illustrating a single cell transmission method according to a first embodiment of the present invention.

Referring to FIG. 3, the single cell transmission method according to the first embodiment of the present invention will be described on the assumption of Case 1 of FIG. 3.

The base station 300 requests reception intention for each MBMS service through a broadcast channel of the system in order to determine the number of terminals 10 before starting the MBMS service or while the service is in progress (S310).

If there is a service reception intention, the terminal 10 obtains location information of a control channel in the broadcast channel, and responds to the service reception intention to the allocated feedback channel (S320).

The base station 300 determines the number A of the terminals 10 identified by the reception intention response, and the number A of the identified terminals 10 is smaller than a predetermined single cell and multi-cell threshold. Therefore, a single cell transmission method is determined (S330). The base station 300 allocates a common feedback channel for a single cell through a control channel (S340), and transmits single cell MBMS service data through a transmission channel (S350).

After decoding the received service data, the terminal 10 performs a CRC check to determine whether an error has occurred in the data packet (S360). When an error occurs as a result of the CRC test, an error report is performed through the common feedback channel (S370).

The base station 300 retransmits corresponding MBMS data according to the error report of the terminal 10 (S380). Here, retransmission means that retransmission of MBMS data retransmits data already transmitted in order to correct an error caused by a poor wireless channel environment. For example, a hybrid retransmission (HARQ) scheme may be included.

According to an embodiment of the present invention, it is preferable that the base station 300 does not transmit service data in a multiplexing manner when a plurality of multimedia broadcast multicast services exist in a cell in such a single cell transmission. This is because, when multiplexed, the terminal 10 may perform an error report on a common feedback channel even for an error of service data that the terminal 10 does not wish to receive, thereby inducing unnecessary retransmission.

4 is a flowchart illustrating a multi-cell transmission method according to a second embodiment of the present invention.

Referring to FIG. 4, the multi-cell transmission method according to the second embodiment of the present invention will be described on the assumption of the case 3 of FIG. 3, but the process for the base station 300 to determine the number of terminals 10. Since steps S410 and S420 are similar to those of FIG. 1, description thereof is omitted.

The base station 300 determines the number of the terminals 10 identified by the reception intention response, and transmits the multi-cells when the determined number of the terminals 10 is larger than a predetermined single cell and multi-cell threshold. Determine in the manner (S430). At this time, the number A of terminal devices 10 in one cell is smaller than a predetermined single cell and multi-cell threshold, but the total number of terminals 10 in seven cells (7 * A) is in advance. Multi-cell service is performed because the number is greater than the determined single-cell and multi-cell threshold.

The base station 300 anticipates that the number A of terminals 10 of each cell is smaller than the frequency of use of a predetermined feedback channel, and allocates a common feedback channel to the terminal 10 for each cell (S440). Through the multi-cell MBMS service data is transmitted (S450).

After decoding the received service data, the terminal 10 performs a CRC check to determine whether an error occurs in the data packet (S460). When an error occurs as a result of the CRC test, an error report is performed through the common feedback channel for each cell (S470).

The base station 300 retransmits the corresponding MBMS data according to the error report of the received terminal 10 (S480).

According to an embodiment of the present invention, when a plurality of multimedia broadcast multicast services are transmitted in a cell in a multi-cell transmission that performs common feedback as in Case 3, the base station 300 multiplexes the services to prevent unnecessary retransmissions. It is preferable not to transmit.

5 is a flowchart illustrating a multi-cell transmission method according to a third embodiment of the present invention.

Referring to FIG. 5, the multi-cell transmission method according to the third embodiment of the present invention will be described on the assumption of Case 2 and Case 4 of FIG. 3, but the base station 300 determines the number of terminals 10. Steps S510 and S520, which are processes for the above, are similar to those of FIG. 1, and thus description thereof is omitted.

The base station 300 determines the number of the terminals 10 identified by the reception intention response, and if the number S of the terminals 10 in at least one or more single cells is larger than a predetermined single cell and multiple cell threshold, It is determined by the cell transmission method (S530). Here, the number S of the terminals 10 means a number greater than a predetermined single cell and multi-cell threshold.

Subsequently, the base station 300 anticipates that the expected frequency of the feedback is greater than the frequency of use of the predetermined feedback channel so that the terminal 10 does not perform the error report on the common feedback channel. That is, the multi-cell MBMS service data is transmitted through the transmission channel without assigning the common feedback (S540).

In case of Case2 and Case4, the base station 300 retransmits data in a CC (Chase combing) or IR (Incremental Redundancy) scheme to a certain number of times for all MBMS data of multiple cells (S560). Diversity gain can be achieved by transmitting at the same time. In this case, when retransmitting data, a new parity bit is added to the retransmitted data in order to further gain channel coding. The CC scheme is a scheme in which retransmitted data transmits the same data as previously transmitted data.

Meanwhile, the base station 300 multiplexes and transmits a plurality of services in order to prevent unnecessary retransmission when a plurality of multimedia broadcast multicast services are transmitted in a cell in a multi-cell transmission that does not perform common feedback. At this time, the base station 300 may transmit a plurality of services in different traffic sizes according to time. For this reason, for example, if the multiplexing is not performed, a waste of resources transmitted without data to the radio resource occurs when the traffic cannot fill the radio resource space. Thus, multiplexing when transmitting a plurality of services has the advantage of reducing the waste of radio resources.

In a multi-cell transmission method using a common feedback channel, a feedback channel can be allocated to each cell and retransmission can be performed for each cell. If the multiple cells simultaneously perform retransmission, it takes time to collect and process feedback channel information allocated for each cell in order to determine whether the multiple cells retransmit at the same time, and the complexity of feedback processing may occur. Can be. Therefore, a method of performing retransmission for each cell has an advantage of reducing system complexity and data reception time. And, in the case of multi-cell transmission without the terminal 10 generating an error in the cell, there is an advantage that the radio resource to be used can be used for other data transmission.

Meanwhile, according to an embodiment of the present invention, in order to prevent unnecessary data transmission when the terminal 10 receiving the broadcast multicast service does not exist, the 3GPP MBMS service performs counting and recounting. .

Here, the count means counting the number of the terminals 10 before starting the service as described above, and the retweezer means counting the number of the terminals 10 during the service.

The base station 300 determines the number of terminals 10 receiving the broadcast multicast service through the aggregation and re-aggregation process, and determines how to perform the service. That is, in the process of aggregation and re-aggregation, the terminal 10 sends a response to the base station 300 when there is a willingness to receive a broadcast multicast service. In this case, when the terminal 10 is in a connected state, the terminal 10 receives a radio resource or performs a response using a radio resource that has already been allocated. In contrast, when the terminal 10 is in the IDLE state, the terminal 10 may perform a response using a wireless access channel.

The common feedback channel proposes a method of allocating feedback channels to each other according to whether the terminal 10 is in a connected state or an IDLE state.

The connected terminal 10 has a feedback channel that is already allocated, for example, if there is a feedback channel that is already allocated for a unicast service, the channel 10 is used as it is.

On the other hand, the terminal 10 in the IDLE state does not have an assigned feedback channel, and uses a part of the unicast feedback channel that can be used by the terminal 10 in the connected state as a common feedback channel. That is, the terminal 10 in the IDLE state may allocate and use a part of the 3GPP random access channel IEEE 802.16 ranging channel as a shared channel.

At this time, since the size of the feedback channel in the connected state is smaller than the feedback of the terminal 10 in the IDLE state, when an error occurs simultaneously in the connected state and the terminal 10 in the IDLE state, the terminal 10 in the connected state has priority. Feedback can be transmitted to minimize system uplink interference. That is, the present invention gives a feedback priority to the terminal 10 in the connected state when an error occurs in the terminal 10 in the connected state and the IDLE state at the same time.

When the base station 300 receives the feedback from the connected terminal 10 and informs the location of the retransmission data through the L1 / L2 control channel, the terminal 10 in the IDLE state retransmits the data without transmitting the feedback. There is an advantage that can be received.

On the other hand, the base station 300, which has received an error report through the common feedback channel, informs the terminal 10 of which (specific) radio resource the multimedia broadcast multicast service data is retransmitted using the L1 / L2 control channel. At this time, the base station 300 may transmit the L1 / L2 control channel in a synchronous hybrid retransmission (Synchronous HARQ) method at a predetermined time. The reason for transmitting the L1 / L2 control channel at a predetermined time is to minimize power consumption of the terminal 10 in the IDLE state.

After the service is started, the base station 300 or the network checks whether there is a terminal receiving the service as a shared feedback channel. When the error reporting is not performed for a predetermined time due to the good wireless channel situation of all the terminals 10, the terminal 10 responds through the shared channel by transmitting an L1 / L2 control channel allocated as a multimedia broadcast multicast notification channel. Do it.

Here, the base station 300 or the network is assigned a random probability value to the terminal 10 in order to prevent a large number of terminals 10 at the same time to generate a large interference to the neighboring cell at the same time, the terminal 10 is random probability In response to this, the common feedback channel may be used to perform a response. In this case, the announcement channel for the multimedia broadcast multicast service is transmitted to the L1 / L2 control channel, and an identifier for each service is assigned and transmitted only at a predetermined time. The reason why the terminal 10 is used only for a predetermined time is to minimize the power of the terminal 10 when reading the known channel when the terminal 10 is in the IDLE state.

Meanwhile, when several operators (carriers or carriers) exist in neighboring cells, and different services are serviced at different frequencies, operators may allow a service to the terminal 10 that is not subscribed to the operator. have. In this case, when the terminal 10 wishes to receive a service not provided by the subscribed operator, the terminal 10 needs frequency and parameter information required for receiving the service.

In this case, the terminal 10 receives a service provided from an unsubscribed operator and moves to another frequency, called a frequency layer convergence, and after the service is terminated, the terminal 10 returns to the subscribed operator frequency. This is called frequency layer dispersion.

In general, a 3GPP WCDMA system does not use an L1 / L2 control channel to perform frequency layer convergence and frequency layer dispersion.

However, the system according to an embodiment of the present invention proposes a method of using the L1 / L2 control channel for a known purpose when performing frequency layer convergence and frequency layer dispersion.

For example, when the first operator cell to which the terminal 10 subscribes does not provide a service that the terminal 10 wants to receive and is provided by a second operator who does not subscribe, the terminal 10 subscribes to the first operator to which the terminal 10 subscribes. It is known to perform a service desired by another second operator from the cell of the L1 / L2 control channel, and receives the service on another frequency.

Next, after the desired service is terminated, the terminal 10 receives a notification of returning to the first operator cell from the L1 / L2 control channel provided by the second operator cell receiving the service and returns to the first operator cell to which the subscriber has subscribed. Can be.

In general, in the case of a unicast service, the terminal 10 reports the end of the service to the base station 300 and the network. This is a procedure for the base station 300 and the network to return the radio resource and the identifier to the other terminal.

In the multimedia broadcast multicast service according to an embodiment of the present invention, when the terminal 10 terminates the service, a method of not reporting the service termination is proposed. This is because, when a small number of terminals 10 report service termination, a small amount of radio resources required for reporting are consumed, but a large number of radio resources are consumed when many terminals 10 report.

As described above, according to an exemplary embodiment of the present invention, when a plurality of multimedia broadcast multicast services are transmitted in a cell in a multi-cell transmission that does not perform common feedback, a plurality of services are transmitted with different traffic sizes according to time. This has the effect of preventing unnecessary retransmissions.

In addition, according to an embodiment of the present invention, since the HARQ scheme with feedback is used in the multimedia broadcast multicast service, the L1 / L2 control channel may be used for retransmission and notification, and thus may be quickly processed in the physical layer of the terminal 10. In addition, the terminal 10 in the IDLE state has an advantage of receiving the retransmitted data without transmitting the feedback.

In addition, the present invention can prevent the unnecessary data transmission and retransmission by inspecting the case that the terminal 10 receiving the service does not exist after starting the MBMS service, and can control the amount of interference due to feedback overhead It works.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded And such an embodiment can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

1 is a diagram illustrating a network for providing an MBMS service according to an exemplary embodiment of the present invention.

2 illustrates a method for multimedia broadcast multicast transmission for each case according to the number of terminals according to an embodiment of the present invention.

3 is a flowchart illustrating a single cell transmission method according to a first embodiment of the present invention.

4 is a flowchart illustrating a multi-cell transmission method according to a second embodiment of the present invention.

5 is a flowchart illustrating a multi-cell transmission method according to a third embodiment of the present invention.

Claims (19)

A method for providing a multimedia broadcast multicast service (MBMS) by a base station, a) determining the number of terminals receiving the multimedia broadcast multicast service; b) determining a single cell or multi-cell transmission scheme by comparing the number of terminals identified in step a) with a predetermined single cell and multi-cell threshold; c) receiving an error report via a common feedback channel assigned to the terminal after the multimedia broadcast multicast service is started; And d) performing data retransmission according to the error report to the terminal; Service providing method comprising a. The method of claim 1, Step a) is Requesting the terminal to receive the multimedia broadcast multicast service by the terminal through a broadcast channel; And Receiving a reception intention for each multimedia broadcast multicast service through a feedback channel allocated to the terminal; Service providing method comprising a. The method of claim 1, B), Determining by the single cell transmission method when the number of terminals is smaller than the threshold; And Allocating a common feedback channel for the single cell via a control channel Service providing method comprising a. The method of claim 1, B), Determining by the multi-cell transmission method when the number of terminals is larger than the threshold; And Allocating a common feedback channel to each cell if the number of terminals of each cell does not exceed a frequency of use of a predetermined feedback channel; Service providing method comprising a. delete The method of claim 4, If the number of terminals of each cell exceeds the frequency of use of the feedback channel, the common feedback channel is not allocated. And multi-cell retransmitting data a certain number of times simultaneously so as to obtain diversity gain of the multi-cell transmission. The method of claim 1, Allocating an identifier and a random probability value for each service using a L1 / L2 control channel as a notification channel for a multimedia broadcast multicast service when there is no error report for a predetermined time from the terminal; And Receiving a response from the terminal through the common feedback channel according to the random probability value Service providing method comprising a. The method of claim 7, wherein The random probability value is, And a notification channel is transmitted through the control channel and is transmitted only at a predetermined time. The method of claim 1, Between steps c) and d), And transmitting a retransmission time according to the feedback channel at a predetermined time. And transmitting at least one of a location of a radio resource of retransmission data and a hybrid retransmission (HARQ) variable value through an L1 / L2 control channel. The method of claim 6, The retransmission is to perform a hybrid retransmission (HARQ) using a feedback channel, Do not multiplex the multimedia broadcast multicast service when using the common feedback channel; or And if the common feedback channel is not used, performing the multiplexing. 11. The method of claim 10, The hybrid retransmission (HARQ) is, Giving priority to feedback to the first terminal in the connected state, and allowing the second terminal in the IDLE state to receive the retransmitted data without performing the feedback. The method of claim 7, wherein The L1 / L2 control channel, And at least one of a frequency layer convergence and a frequency layer dispersion operation. An apparatus for providing a multimedia broadcast multicast service, A communication unit for determining the number of terminals receiving the multimedia broadcast multicast service; And And a controller for determining a single cell or a multi-cell transmission scheme by comparing the identified number of terminals with a predetermined single cell and a multi-cell threshold. The controller may retransmit the data a predetermined number of times without allocating a common feedback channel when the number of terminals of each cell exceeds the frequency of use of the feedback channel. The method of claim 13, Wherein, And requesting a reception doctor for each multimedia broadcast multicast service through a broadcast channel to the terminal, and receiving the reception doctor through a feedback channel assigned to the terminal. The method according to claim 13 or 14, The control unit, A control channel for notifying at least one of a multimedia broadcast multicast service-specific identifier, data transmission time information, and location information of a radio resource, a notification channel for identifying the number of terminals or for notifying a change of a specific notification, and providing feedback from the terminal. And at least one of feedback channels for receiving. 16. The method of claim 15, The control unit, And determining the single cell transmission method when the number of terminals is smaller than the threshold, or determining the multi-cell transmission method when the number of terminals is larger than the threshold. delete 17. The method of claim 16, The control unit, And a L1 / L2 control channel is used as the notification channel when there is no error report for a predetermined time from the terminal. 17. The method of claim 16, The control unit, When the common feedback channel is used in the multi-cell transmission scheme, the multimedia broadcast multicast service is not multiplexed, and when the common feedback channel is not used, the service is provided. Device.

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