KR20050071318A - Method for combinimg selective in a mobile communication system - Google Patents

Abstract

The present invention relates to a method for selectively combining the same broadcast data received through a plurality of paths in a mobile communication system. To this end, in the present invention, the selective association assistance data is periodically provided by the radio network controller through a common control channel for each cell. On the other hand, the mobile terminal checks by the selective combining auxiliary data whether duplicate broadcast data is received from the plurality of cells in a situation where the same broadcast service is provided from the plurality of cells. The selective combining may be performed based on a result of the check by the selective combining assistance data.

Description

Selective coupling method in mobile communication system {METHOD FOR COMBINIMG SELECTIVE IN A MOBILE COMMUNICATION SYSTEM}

The present invention relates to a data combining method in a mobile communication system, and more particularly, to a method for selectively combining the same broadcast data received through a plurality of paths.

Today, due to the development of communication technology, a code division multiple access (CDMA) mobile communication system provides a packet service for transmitting a large amount of data such as packet data and circuit data, as well as voice service. Furthermore, it is developing into multimedia broadcasting / communication capable of transmitting multimedia services. However, in a typical mobile communication system, since radio transmission resources are limited, it is not very efficient to transmit high-speed data one-to-one. For example, in order to provide a 64 kbps video streaming service to a user equipment (hereinafter referred to as "UE"), a radio resource capable of transmitting 64 kbps data should be allocated to the UE. However, if there are n such UEs, the demand for radio resources to allocate will also increase n times. Alternatively, if multiple UEs wish to receive the same service, a method of providing the same service through a common channel is possible. In this case, a service may be provided using the same radio resource regardless of the number of UEs located in the same cell and wishing to receive the same service. This enables efficient use of radio resources.

Accordingly, in order to support multimedia broadcasting / communication, a broadcasting service that provides a service to a plurality of UEs from one or several multimedia data sources has been discussed. A representative example thereof will be referred to as a multimedia broadcast / multicast service (hereinafter referred to as an MBMS service) proposed in 3GPP (3rd Generation Project Partnership: hereinafter referred to as "3GPP").

The MBMS service supports multimedia transmission forms such as real-time video, audio, still images, text, etc., and can provide audio data and video data simultaneously according to the application of the multimedia transmission format. Therefore, the MBMS service requires a large amount of transmission resources. In addition, the MBMS service may be provided through a broadcast channel in that multiple UEs may request the same MBMS service.

The MBMS service can be provided in two types of services. First of all, there is a point-to-point (hereinafter referred to as "PtP") service that serves a desired MBMS service for each UE. In this case, dedicated channels should be allocated to the UEs. Secondly, there is a point-to-multi-point (hereinafter referred to as "PtM") service that provides MBMS data for a plurality of UEs that request the same MBMS service. In this case, a common channel should be allocated for UEs that request the same MBMS service.

The aforementioned MBMS service is a service for efficiently transmitting the same data to multiple UEs in an asynchronous mobile communication system (hereinafter referred to as a "UMTS mobile communication system"). In particular, the MBMS service is advantageous for multimedia transmission with a large demand for radio transmission resources. Therefore, as the MBMS service may be used not only for high speed multimedia services but also for various purposes, applications suitable for the MBMS service will increase further in the future.

Even if the same MBMS service is provided to multiple UEs using the common channel, there are still limitations on radio resources. According to simulations, in order to maintain a block error rate of 10e-2 over 80 to 90% of cells while transmitting 64kbps data through a common channel, more than 30% of the cell's available transmission power must be used. .

Such research results may cause the following problems.

First, in order to provide MBMS service of satisfactory quality for all UEs located in one cell, most of the available transmission outputs of the cell should be used for one service.

Secondly, when limiting the available transmit power of a cell, UEs located at the cell boundary are likely to experience quality degradation.

In order to alleviate the above-mentioned problem, it has been proposed that a UE located at the cell boundary receives data from two or more cells when a particular service is simultaneously transmitted in several adjacent cells. However, only the discussion of the concept was carried out, and no concrete way to realize it was presented. Therefore, when a specific service is simultaneously transmitted in several neighboring cells, a proper scheme for exchanging control signals between the base station and the UE and by installing a new device in the UE to receive data transmitted from the various cells and then use the data appropriately This desperation will be asked.

Accordingly, an object of the present invention to solve the above problems is to provide a selective combining method for a mobile terminal located at a cell boundary to smoothly receive a broadcast service.

Another object of the present invention is to provide a selective combining method for maximizing the efficient use of forward wireless transmission resources.

It is still another object of the present invention to provide a method of selecting and combining only data having no error among the same data received through a plurality of paths.

It is still another object of the present invention to provide a method of performing selective combining using serial numbers assigned to data.

Another object of the present invention is to provide a method for performing selective combining using a serial number of a radio link control (RLC) layer.

It is still another object of the present invention to provide a method for identifying data received through different paths by serial numbers of a radio link control (RLC) layer and performing selective combining based on the identification result. .

Another object of the present invention is to provide a method for performing selective combining using a serial number of a forward error correction (FEC) layer.

It is still another object of the present invention to provide a method for identifying data received through different paths by serial numbers of a forward error correction (FEC) layer and performing selective combining based on the identification result. .

It is still another object of the present invention to provide a method of transmitting a serial number identifier for each cell in a network in which a plurality of serial number assigners exist.

Still another object of the present invention is to provide a method for determining whether to perform selective combining by a serial number identifier transmitted from a mobile terminal by a network.

It is still another object of the present invention to provide a method of performing selective combining of data from the serving cell and the target cell when the serial number identifier from the target cell and the serial number identifier from the serving cell match. Is in.

It is still another object of the present invention to provide a method of not performing selective combining of data from the serving cell and the target cell if the serial number identifier from the target cell and the serial number identifier from the serving cell do not match. In providing.

In a first aspect for achieving the above object, the present invention provides a mobile terminal, a serving cell for providing an arbitrary broadcast service through a main link set by the mobile terminal, and an auxiliary set by the mobile terminal. And at least one target cell among cells adjacent to the serving cell providing the arbitrary broadcast service through a link, and a wireless network controller providing broadcast data according to the arbitrary broadcast service to the serving cell and the target cell. A method for selectively combining broadcast data from the serving cell and the target cell by the mobile terminal in a mobile communication system, the method comprising: checking whether broadcast data is repeatedly received from the serving cell and the target cell; When broadcast data is repeatedly received, any one of the serving cell or the target cell Selecting only the broadcast data received from the cell and discarding the broadcast data received from the remaining cells; and reconfiguring the selected broadcast data in the order transmitted from the wireless network controller through the corresponding cells. do.

In a second aspect for achieving the above object, the present invention provides a mobile terminal, a serving cell for providing an arbitrary broadcast service through a main link established by the mobile terminal, and an auxiliary set by the mobile terminal. And at least one target cell among cells adjacent to the serving cell providing the arbitrary broadcast service through a link, and a wireless network controller providing broadcast data according to the arbitrary broadcast service to the serving cell and the target cell. In the mobile communication system, the mobile terminal selectively combines the broadcast data from the serving cell and the target cell, the apparatus comprising: checking whether the same broadcast data is received from the serving cell and the target cell is duplicated, and the broadcast If data is duplicated, one of the serving cell or the target cell And a redundancy checker that selects only broadcast data received from the cell and discards the broadcast data received from the remaining cells, and a reconfiguration buffer for reconfiguring the selected broadcast data in the order transmitted from the wireless network controller through the corresponding cells. It is characterized by.

In a third aspect for achieving the above object, the present invention provides a mobile terminal, a serving cell for providing an arbitrary broadcast service through a main link set by the mobile terminal, and an auxiliary set by the mobile terminal. And at least one target cell among cells adjacent to the serving cell providing the arbitrary broadcast service through a link, and a wireless network controller providing broadcast data according to the arbitrary broadcast service to the serving cell and the target cell. A mobile communication system, wherein the mobile terminal provides selective combining assistance data in the radio network controller to perform selective combining on broadcast data from the serving cell and the target cell. Sequentially within a predetermined range for each broadcast data according to a service Providing a monotonically increasing sequence number to the mobile terminal through the serving cell and the target cell, initializing a sequence number version when the arbitrary broadcast service is first started, and performing the advance on the broadcast data. Increasing the sequence number version by one when a minimum sequence number is assigned to the next broadcast data after a maximum sequence number in a predetermined range is given; and adding the sequence number version to the common control channel and the target of the serving cell. Periodically transmitting to the mobile terminal through a common control channel of a cell.

In a fourth aspect for achieving the above object, the present invention provides a method for the mobile terminal to selectively combine the broadcast data in a mobile communication system including a mobile terminal for receiving broadcast data from a plurality of cells. The method may include: forming a window by an arbitrary upward end point and an arbitrary downward end point, storing only broadcast data having a serial number not included in the window in the rearrangement buffer, and storing the rearranged buffer After changing the window by a serial number of broadcast data, transmitting the broadcast data whose serial number is not included in the changed window among the broadcast data stored in the rearrangement buffer to a higher layer, wherein the Any upward endpoint is one of the serial numbers of the broadcast data received so far. Chapter is determined by a higher sequence number, the downward end point is characterized by a value determined by taking the result of the modular operation value obtained by subtracting the size of the window to a predetermined natural number in the direction of the end point.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. DETAILED DESCRIPTION In the following detailed description, one exemplary embodiment of the present invention will be presented to accomplish the above technical problem. And other embodiments that can be presented with the present invention are replaced by the description in the configuration of the present invention. Meanwhile, in the embodiment of the present invention to be described below, only the MBMS service is limited, but it is obvious that the same may be applied to all broadcast services.

Before examining the present invention in detail, the terms to be frequently used are briefly summarized as follows.

Common Control Channel (MCCH): A channel in which information related to MBMS service is broadcast for each cell. The type of MBMS service provided for each cell and configuration information of a radio bearer for which the MBMS service is provided may be broadcast through the channel. In addition, various information that a UE needs to know in order to receive MBMS service may be transmitted through the common control channel.

Radio Link Control Packet Data Unit (RLC PDU): In the UMTS mobile communication system, the second layer is composed of a Radio Link Control (RLC) layer and a Medium Access Control (MAC) layer. The RLC layer configures the data delivered by the upper layer to an appropriate size and then inserts a header to pass the data to the lower layer (MAC layer) or interprets the header of the data transferred by the lower layer (MAC layer) to take an appropriate action and then move to the upper layer. It serves to convey. In this case, data exchanged between the RLC layer and a lower layer (MAC layer) is called an RLC PDU.

Forward Error Correction Packet Data Unit (FEC PDU): A newly defined layer for using outer coding in MBMS service. The FEC layer configures the data delivered by the upper layer to an appropriate size, and then inserts a header and delivers the data to the lower layer (RLC layer) or interprets the header of the data transmitted by the lower layer (RLC layer) and takes appropriate action. It serves to convey. In this case, data exchanged between the FEC layer and a lower layer (RLC layer) is called an FEC PDU.

RLC PDU SN (Radio Link Control Packet Data Unit Sequence Number): A serial number included in the header of the RLC PDU, which is monotonically increased in sequence according to the transmission order. It is used as information for distinguishing RLC PDUs for selective combining proposed in the present invention. In the present invention, "RLC SN" or "SN".

FEC PDU Forward Error Correction Packet Data Unit Sequence Number (SN): This is a serial number included in the header of the FEC PDU and sequentially monotonically increased according to the transmission order. It is used as information for distinguishing FEC PDUs for selective combining proposed in the present invention. In the present invention, it is referred to as "FEC SN".

Selective Combined Auxiliary Data: Data used together with RLC SN or FEC SN to perform selective combining by distinguishing the same broadcast data among broadcast data received from a plurality of cells. In the present invention, the RNC SN version or the FEC SN version and the selective combining indicator (hereinafter referred to as "SC identifier") are proposed as the selective combining assistant data.

RNC SN version: This is a count of the number of times the RLC SN is reset by the transmission of the RLC PDU, and is used when the RLC SN cannot determine whether the same RLC PDUs received from different cells due to the transmission delay.

FEC SN version: A count of the number of times the FEC SN is reset by the transmission of the FEC PDU, and is used when the FEC SN cannot determine whether the FEC PDUs received from different cells are identical due to the transmission delay.

SC identifier: Information indicating whether a specific MBMS service provided in an arbitrary cell supports selective combining.

In general, broadcast services often have one broadcast service provided simultaneously in adjacent cells. In particular, the MBMS service, which is one of broadcast services, is even more so. Therefore, when the UE receives broadcast data according to the same broadcast service from a plurality of cells, the UE uses only broadcast data in which no error occurs among the broadcast data. This is referred to as selective combining in the present invention. By using the selective coupling, a selective coupling gain can be obtained. For example, suppose that a UE receives broadcast data according to a specific broadcast service from both Cell # 1 and Cell # 2. In this case, when an error occurs in the broadcast data received in the cell # 1 and no error occurs in the same broadcast data received in the cell # 2, only the broadcast data received in the cell # 2 is used. As a result, it is possible to obtain broadcast data in which no error occurs.

In order to perform such selective combining, the UE must establish a radio link with a plurality of cells, and must be able to determine the same data among broadcast data received through different radio links. The present invention proposes a method of using selective combining auxiliary data and RLC SN or FEC SN to identify the same broadcast data.

A. First Embodiment

First, using the SN of the RLC PDUs received from the multiple links by the UE, in order to identify the RLC PDUs, the following must be satisfied in the network.

First, RLC PDUs of the same size must be transmitted on the links to be subjected to selective aggregation. This is possible by setting the same RLC PDU size for the links that will perform the selective aggregation.

Secondly, the same serial number should be assigned to RLC PDUs transmitted on the links to be subjected to selective aggregation. That is, if the RLC PDU received on the primary link and the RLC PDU received on the secondary link have the same SN, they should be the same RLC PDU. It is automatically met if the first condition is met. That is, the RLC PDUs transmitted through the primary link and the secondary link are serial numbered RLC PDUs after the same MBMS data transmitted from the core network is composed of RLC PDUs of the same size.

Thirdly, the UE should be able to identify RLC PDUs of links to be subjected to selective aggregation using the RLC SN. Since the RLC SN has a value between 0 and 127, SNs of RLC PDUs received at the same time through the primary link and the secondary link by the UE should not differ by more than 128/2 = 64. If the difference is greater than 64, the UE cannot determine the exact order of the RLC PDUs received on the secondary link. For example, if at any point in time a RLC PDU with an SN from the primary link is received and an RLC PDU with an SN from (a + 64) from the secondary link, then the UE receives an RLC PDU to receive from the secondary link. It is not possible to determine whether the PDU was transmitted by 64 RLC PDUs before the RLC PDU received from the primary link or the PDU to be transmitted by 64 RLC PDUs.

On the other hand, as a method of satisfying the third condition described above, two can be proposed. The first is to synchronize the data transmission per link in the network to some extent. Second, there is no restriction on data transmission per link, but a method of transmitting ancillary data that can be used as an identifier of RLC PDUs for each cell.

The present invention to be described below is constructed based on the second solution. However, even if the first solution is used, the essential part of the present invention is the same. For example, the operation of detecting the duplicately received data and the reconfiguring order of the selective combiner are the same.

In order to apply the second scheme, in the present invention, the UE periodically broadcasting the selective combining auxiliary data for each cell, and receiving the broadcasting data from two or more cells, may use the sequence number assigned to the selective combining auxiliary data and the broadcasting data. By using SN (Sequence Number), selective combining is performed.

In general, what is proposed in the present invention, the RNC providing any MBMS service announces the selective association assistance data for the MBMS service for each cell in which the MBMS service is provided. The selective association assistance data means data that the UE should recognize in order to perform selective association, for example, data indicating whether a specific MBMS service is capable of selective combining in the cell (SC identifier) or transmitted in the cell. May be ancillary data (RLC SN version) used for identifying the RLC PDU. When the UE finds another cell providing the MBMS service that it desires in a good wireless environment while receiving the MBMS service from any cell, the UE acquires the optional combined assistance data known from the found cell. The selective combining assistance data is used to perform a selective combining operation on MBMS data transmitted from the plurality of cells. As described above, the selective combining operation refers to an operation of discarding redundantly received RLC PDUs of the RLC PDUs received through the primary link and the secondary link, and delivering the reconfigured RLC PDUs to the RLC entity in the order of transmission. . The optional combined assistance data may be used to identify an RLC PDU received through a primary link and a secondary link in the process.

In the present invention, an optional combiner is provided as a device for performing the selective combining operation, and the selective combiner is located between the MAC layer and the RLC layer. The optional combiner is configured with the setting of the secondary link and is not used in the situation where only one of the plurality of links currently set exists. The secondary link indicates a physical layer / MAC layer to process MBMS data transmitted in a new cell.

As a preferred embodiment of the present invention, an operation of performing selective combining using the RLC SN version and the SC identifier as the selective combining auxiliary data will be described.

1 is a view showing the structure of a radio access network (hereinafter referred to as "UTRAN") in a UMTS mobile communication system for applying an embodiment of the present invention. In FIG. 1, a UTRAN is composed of a cell, a base station (hereinafter referred to as "Node B"), and a radio network controller (RNC). There may be a plurality of RNCs in the UTRAN, and each of the RNCs may control a plurality of Node Bs. Each Node B controls a plurality of cells. One RNC, Node Bs controlled by the RNC, and a plurality of cells controlled by the Node Bs are collectively referred to as a Radio Network Subsystem (RNS). In FIG. 1, only the structure of one RNS among a plurality of RNSs constituting the UTRAN is shown, and it is assumed that each of the two Node Bs constituting the RNS controls one cell. On the other hand, the cell typically only serves as a physical layer of the Node B to which it belongs. Therefore, in the embodiment of the present invention to be described later it should be noted that the Node B and the cell can be used interchangeably.

Referring to FIG. 1, the RNC 110 configures MBMS data provided from a core network into RLC PDUs and provides them to two adjacent cells 112 and 114. In addition, the RNC 110 periodically transmits selective combining assistance data for each MBMS service through the MCCH for each of the two neighbor cells 112 and 114. The optional association assistance data includes an RLC SN version and an SC identifier. The RLC SN version is auxiliary data used by the UE 116 to identify the back and forth relationship between the RLC PDUs received on the primary link and the RLC PDUs received on the secondary link. The RLC SN of the RLC PDU is primarily used to identify the front and back relationship between the RLC PDUs received from each link. However, since the RLC SN is only 7 bits, it may not reflect the difference in transmission conditions that may occur between links. For example, if there is a transmission difference of several hundred RLC PDUs between the primary link and the secondary link, the RLC SN is of no help in identifying the back and forth relationships of the received RLC PDUs. In other words, if the x-th RLC PDU is being transmitted on the primary link but the x + 500th RLC PDU is being transmitted on the secondary link, then an RLC SN with a value between 0 and 127 can help identify the back and forth relationships of the received RLC PDUs. This doesn't work. The RLC SN version is a parameter that creates an effect of extending the SN so that the UE can identify the RLC PDUs even when the transmission situation difference occurs. The RNC 110 increments the RLC SN version by 1 each time the SN of the RLC PDU configured for each link wraps, and periodically broadcasts the RLC SN version. An example of the recursion of the SAN can be assumed to return to zero at 127.

The SC identifier constituting the selective coupling assistance data is a value indicating whether selective coupling of the RLC PDU transmitted on the link and the RLC PDU on another link is possible. The SC identifier may be determined based on whether the RLC configuration of the link satisfies the aforementioned preconditions 1 and 2. For example, if a particular link is driven later than the links of adjacent cells, the second precondition that the SN grants of the RLC PDUs must be the same is not met. For such a link, the SC identifier can be set to 'enabled' to instruct the UEs not to perform selective combining. To illustrate the situation in which the above case actually occurs, the number of UEs that want to receive the MBMS service in any cell was not large enough to set the point to multipoint transmission at the time of the start of any MBMS service. However, there may be a case where several UEs move to the cell and start PTM transmission to the cell while the MBMS service is in progress. In this case, since the RLC SN scheme is different between the link of the cell and the link of another cell, the UE cannot perform selective coupling between the link configured in the cell and the link of another cell.

Any UE 116 detects that the wireless signal of the new cell 114 satisfies certain requirements, such as meeting the above threshold value, while receiving the MBMS service through the serving cell 112. The UE 116 then establishes a radio link capable of receiving MBMS service from the new cell 114. In order to establish a radio link with the new cell 114, the UE 116 must interpret the control information transmitted on the MCCH from the new cell 114. The control information includes optional combining assistance data. The UE 116 interprets the control information to determine whether the MBMS service desired by the new cell 114 is provided through a common channel. If the desired MBMS service is provided, check whether the selective combination is possible. If the selective combining is possible, the UE 116 interprets radio bearer information for the MBMS service from the control information to establish a secondary link capable of receiving the MBMS service. The radio bearer is composed of an RLC / MAC / PHY layer, and the link is composed of a MAC and a PHY layer. Accordingly, the UE 116 sets the radio link configured for the new cell 114 as the secondary link and the radio link configured for the serving cell 112 as the primary link.

The UE 116 configures an optional combiner to perform selective combining of RLC PDUs received on the primary link and RLC PDUs received on the secondary link. The UE 116 provides the selective combiner with RLC SN version information corresponding to the primary link and RLC SN version information corresponding to the secondary link. The selective combiner combines the SN of the received RLC PDU with a known RLC SN version, thereby obtaining an extended effect of the RLC SN. In the present invention, the combined value of the RLC SN version and the RLC SN is referred to as an extended RLC SN of the corresponding RLC PDU. The UE 116 uses the extended RLC SN to identify duplicate received RLC PDUs among the RLC PDUs received on the primary link and the secondary link. In addition, one of the duplicated RLC PDUs is discarded, and the other RLC PDU performs a duplication check operation. In addition, the RLC PDUs are sequentially reconfigured for the RLC PDUs provided through the redundancy check so that the RLC PDUs may be sequentially transmitted to the RLC layer. The duplicate check operation and the sequence reconstruction operation are selective combining operations proposed by the present invention.

For the embodiment of the present invention as described above the following operations will be described in detail.

First, signaling between the RNC and the cell and the UE should be proposed to provide selective combined assistance data.

Second, the operation of the RNC to manage and optionally transmit the optional joint assistance data should be proposed.

Third, an operation of performing selective combining by the UE using selective combining assistance data should be proposed.

1. Signaling

Hereinafter, signaling for transmitting selective combining assistance data according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 illustrates a process in which an RNC announces selective combining assistance data for each cell and receives the same by a UE for an embodiment of the present invention. The signaling illustrated in FIG. 3 assumes that the UE has been provided an arbitrary MBMS service through the serving cell, and then starts receiving a good signal through the target cell at any time. The serving cell refers to a cell previously providing any MBMS service to the UE, and the target cell refers to a cell newly providing the MBMS service due to the movement of the UE.

Referring to FIG. 2, the UE receives the MCCH from the serving cell in step 210. The UE, by receiving the MCCH, acquires selective association assistance data along with radio bearer information currently provided through the serving cell and for the type and link establishment of an MBMS service. The selective combining assistance data consists of an SC identifier for identifying whether the serving cell supports selective combining and an RLC SN version for identifying the currently transmitted RLC PDU.

The UE checks whether the desired MBMS service is provided from the serving cell according to the type of the MBMS service. If the desired MBMS service is provided, the UE establishes a radio bearer using radio bearer information corresponding to the MBMS service. The radio bearer may be composed of an RLC layer, a MAC layer, and a PHY layer. The MAC layer and the PHY layer may be defined by the term "link". In the description below, the MAC layer and the PHY layer configured for the serving cell are referred to as a "main link".

Thereafter, the UE checks whether the serving cell supports selective combining by the SC identifier configuring the selective combining assistance data. If the serving cell does not support selective combining, the UE does not perform the selective combining proposed in the present invention. However, if the serving cell supports selective combining, the UE stores an RLC SN version that constitutes the selective combining assistance data.

The UE receives an RLC PDU from the serving cell on the primary link. The UE checks the RLC SN from the received RLC PDU, and if the RLC SN is confirmed as the initial value, increases the stored RLC SN version by one. For example, if a previous RLC PDU with an SN of 127 was received and the SN of the currently received RLC PDU returned to 0, the UE increments the currently stored RLC SN version by one.

The UE monitors whether a good signal is received by receiving signals from neighboring cells in a situation where an MBMS service is provided from the serving cell. Receiving the good signal means having a good wireless environment. When a good signal is detected, the UE recognizes an adjacent cell transmitting the signal as a target cell. In step 220, the UE receives the MCCH from the target cell, thereby obtaining selective coupling assistance data along with radio bearer information currently provided through the target cell and for the type of MBMS service and link establishment. do.

The UE checks whether the desired MBMS service is provided from the target cell according to the type of the MBMS service. The desired MBMS service is an MBMS service currently being provided from the serving cell. If the desired MBMS service is being provided, the UE checks whether the target cell supports selective combining by the SC identifier constituting the selective combining assistance data. If the target cell does not support selective combining, even if the serving cell supports selective combining, the UE does not perform the selective combining proposed by the present invention. In other words, if the target cell does not support selective aggregation, the UE does not configure a secondary link for the target cell. However, if the target cell supports selective combining, the UE configures a radio bearer using radio bearer information corresponding to the MBMS service. The radio bearer may be composed of an RLC layer, a MAC layer, and a PHY layer. In the description below, the MAC layer and the PHY layer configured for the target cell are referred to as "secondary links". When the secondary link is configured, the UE stores an RLC SN version that constitutes the selective association assistance data.

The UE receives an RLC PDU from the target cell on the secondary link. The UE confirms the RLC SN from the received RLC PDU and increments the stored RLC SN version by one when the RLC SN is changed to an initial value.

2. Operation of RNC

In order to implement the present invention, the RNC manages selective combining assistance data and periodically provides it for each cell. Hereinafter, an operation for periodically transmitting selective combining auxiliary data in the RNC will be described in detail.

The RNC periodically transmits selective association assistance data through the MCCH configured for each cell managed by the RNC. The optional combined assistant data is set for each MBMS service. Therefore, if n MBMS services are provided in one cell, n selective coupling assistant data may be periodically transmitted through the MCCH configured for the cell.

First, the RLC SN version constituting the selective association assistant data is managed and transmitted as follows by the RNC.

The RNC configures RLC entities to process MBMS data in cells whose MBMS service is initially requested among cells managed by the RNC. The RLC SN version corresponding to the random MBMS service is initialized to zero. Thereafter, RLC PDUs according to the MBMS service are sequentially transmitted through the RLC entity. In this case, the RLC PDU includes a SN that monotonically increases in sequence according to the transmission order. The SN is monotonically increased starting from zero and up to any predetermined number. As an example, the SN increases from 0 to 127, and returns to 0 after 127. When the SN returns to zero, the RNC increments the RLC SN version by one.

The RLC SN version of each cell managed by the above is periodically announced for the cell in which the arbitrary MBMS service is being provided, so that UEs wishing to perform selective combining for the arbitrary MBMS service in the cell are required to perform the RLC. Make sure you recognize the SN version.

Next, the SC identifier constituting the optional association assistance data is managed and transmitted by the RNC as follows.

The RNC manages an SC identifier indicating whether selective combining is supported for each MBMS service provided through cells controlled by the RNC. In this case, even a cell providing the same MBMS service may be divided into a cell supporting selective combining and a cell not supporting selective combining. In addition, a specific MBMS service may not provide a selective coupling regardless of the cell. By this information the SC identifier is managed by the RNC. The RNC periodically transmits SC identifiers set for each MBMS service for each cell. For example, if the RNC can selectively combine any MBMS service provided through cell # 1, the RNC sets the SC identifier for the arbitrary MBMS service to 'enabled' and periodically broadcasts through the cell # 1. . On the other hand, if the selective coupling is not possible for any MBMS service provided through cell # 2, the RNC sets the SC identifier for the arbitrary MBMS service to 'disabled' and periodically broadcasts through cell # 2.

3. Operation of the UE

Hereinafter, an operation of a UE performing selective combining according to an embodiment of the present invention will be described in detail.

3 is a diagram illustrating a control flow for a UE to perform selective combining according to an embodiment of the present invention. The control flow of FIG. 3 assumes a situation in which a radio link is established between a UE and a serving cell and a specific MBMS service is provided through the radio link.

Referring to FIG. 3, in step 301, the UE receives a signal from neighbor cells and detects whether a good signal among the received signals exists. The definition that the received signal is good can be made in various ways. For example, as a method of using the received signal strength, if the received signal intensity exceeds a predetermined threshold, it may be determined that the signal is good. The presence of the good signal implies that the UE is in close proximity to any neighbor cell (hereinafter referred to as the "target cell") that transmitted the good signal. Accordingly, the UE can simultaneously receive signals from the serving cell and the target cell. Meanwhile, the target cell may be one or more cells.

Assuming that there are a plurality of target cells, the UE receives the MCCH from the target cell in which the best signal is received in step 303. Through the MCCH, identifiers of the MBMS service provided by the target cell, radio bearer information of the provided MBMS service, selective coupling assistance data, and the like are transmitted. The UE checks the information received through the MCCH and proceeds to step 305. In step 305, the UE checks whether the desired MBMS service is provided by the target cell. If the desired MBMS service is provided, the process proceeds to step 307. Otherwise, if the desired MBMS service is not provided, the process proceeds to step 309.

In step 307, the UE determines whether the target cell supports selective combining based on the SC identifier among the checked selective combining assistance data. If it is determined by the SC identifier that the target cell supports selective combining, the process proceeds to step 311. Otherwise, if it is determined that the target cell does not support selective combining, the process proceeds to step 309.

When the UE proceeds to step 309, the UE returns to step 305 after confirming the information received through the MCCH from the target cell in which the next good signal is received. However, in step 311, the UE establishes a radio link, that is, a secondary link, with the target cell in order to receive the MBMS service desired by the UE. The secondary link is established by radio bearer information received through the MCCH. The radio bearer information includes physical layer information, MAC layer information, and the like. The physical layer information is information about a transport channel, and includes code information corresponding to a physical channel, a type of channel coding applied to a physical channel, a channel coding rate, a transmission time interval (TTI), and the like. The MAC layer information includes multiplexing information according to whether multiplexing is applied in the MAC layer and service identifier information according to whether a service identifier is used in the MAC layer. The UE sets a new physical layer by the physical layer information, and sets a new MAC layer by the MAC layer information. The secondary link refers to the newly configured physical layer and MAC layer.

When the secondary link is configured as described above, the UE configures an optional combiner for selective combining in step 313. Thereafter, the selective combiner is connected to the primary link with the serving cell and the secondary link with the target cell, and performs selective combining on broadcast data received through the primary link and the secondary link. A detailed description of the selective coupler will be described later with reference to FIG. 4.

In step 315, the UE continuously monitors whether a situation in which release of the primary link or the secondary link is required occurs. The situation in which the release is required corresponds to a situation in which a signal having an intensity less than a predetermined threshold is received. If such a situation is detected, the UE releases the link with the corresponding cell. For example, if the desired signal is not received through the primary link, the primary link established with the serving cell is released. Otherwise, if a desired signal is not received through the auxiliary link, the auxiliary link established with the target cell is released. If only one link exists in step 315, the UE terminates the selective combining operation by releasing the selective combiner configured in step 317.

4 is a diagram illustrating a structure of a UE for performing an embodiment of the present invention. The structure of the UE shown in FIG. 4 assumes a situation where an optional combiner is configured for selective combining. However, since only the primary link with the serving cell exists, only a configuration of processing a signal received from the serving cell will exist in a situation in which selective coupling is not performed. Therefore, the structure of the UE consists of only the main link 410 composed of the physical layer 412 and the MAC layer 414, and the RLC layer 440 only. Thereafter, when a new MBMS service provided from the serving cell is to be newly provided from a target cell, the UE configures a secondary link with the target cell. The structure of the UE configured with the secondary link is shown in FIG. 4.

Referring to FIG. 4, the UE obtains physical layer information and MAC layer information from the target cell to which the secondary link is to be configured through the MCCH. Thereafter, a new physical layer 422 is set by the physical layer information, and a new MAC layer 424 is set by the MAC layer information. The configuration of the physical layer 422 and the MAC layer 424 means that a new secondary link has been established. The UE then sets up an optional combiner 430 according to the present invention. Thereafter, the selective combiner 430 and the primary link 410 and the secondary link 420 are connected to the lower layer, and the selective combiner 430 and the RLC layer 440 are connected to the upper layer.

The optional combiner 430 includes a duplication checker 432 and a reordering buffer 434. The selective combiner 430 discards the duplicated RLC PDUs among the RLC PDUs received through the primary link 410 and the secondary link 420, and re-removes the duplicated RLC PDUs in the order of transmission. Configure and deliver to the RLC layer 440. That is, the same RLC PDU may be received through the primary link 410 and the secondary link 420. In this case, the redundancy checker 432 constituting the selective combiner 430 discards one of the RLC PDU received through the primary link 410 and the RLC PDU received through the secondary link 420 and the other one. Outputs only RLC PDUs. Meanwhile, the RLC PDUs output from the redundancy checker 432 may not be regarded as having the same order as the transmission order. Therefore, the RLC PDUs output from the redundancy checker 432 are temporarily stored in the reconfiguration buffer 434 and then reconfigured in the transmission order to the RLC layer 440.

In order to determine whether the redundancy checker 432 overlaps the RLC PDU provided from the primary link 410 and the RLC PDU provided from the secondary link 420, separate information is required. As an example of the information, the RLC SN which the RLC PDU has may be used. However, since the RLC SN is the same, it may not necessarily be determined as a duplicate RLC PDU. The reason is that the RLC SN is given with a predetermined period. When the RLC PDU provided through the primary link 410 and the RLC PDU provided through the secondary link 420 have a delay difference deviating from one period, The two RLC PDUs cannot be regarded as duplicates. This can be confirmed through the RLC SN version. As defined above, the RLC SN version is a value changed by the period. Therefore, even if the RLC SNs are the same, it may not be determined as a duplicate RLC PDU when the RLC SN versions are different. In order to solve this problem, the present invention proposes an extended RLC SN (Extended RLC SN) as additional information for identifying the duplication. The extended RLC SN is defined as in Equation 1 below.

Extended RLC SN_x = [RLC SN Version_x II RLC SN_x]

As shown in Equation 1, an extended RLC SN_x of an RLC PDU provided through a link x is a value obtained by concatenating an RLC SN version (RLC SN version_x) and an RLC SN (RLC SN_x) corresponding to the link x. . For example, if the RLC SN version of the primary link is "001" and the SN of the RLC PDU received on the primary link is "0000111", the extended RLC SN is "0010000111".

Accordingly, the redundancy checker 432 obtains extended RLC SNs for each of the RLC PDUs provided from the primary link 410 and the RLC PDUs provided from the secondary link 420, and compares the extended RLC SNs. You can check whether or not. However, it does not replace the SN of RLC PDUs with the extended RLC SN. The extended RLC SN is used only to determine the front-rear relationship between the RLC PDUs received from the primary link 410 and the secondary link 420.

Specific Behavior of Selective Coupling at the UE

Hereinafter, the operations of the redundancy checker and the reconfiguration buffer for selective coupling in the UE according to an embodiment of the present invention will be described in detail.

Example of operation of redundancy check unit

The redundancy checker 432 discards the RLC PDUs that have been repeatedly received through the primary link and the secondary link, or checks the unreceived RLC PDUs (hereinafter, referred to as "final lost PDUs"). That is, the redundancy checker 432 delivers only one RLC PDU among the plurality of RLC PDUs received from both the primary link and the secondary link to the upper layer, and discards the remaining RLC PDUs. In this case, the plurality of RLC PDUs may be received with a predetermined delay. Meanwhile, 'final lost PDU' not received through any one of the primary link and the secondary link is identified and notified to the upper layer. There may be various ways to implement the above-described operation of the redundancy checker 432. The following description may be one of the implementation examples.

First, variables to be used in the implementation example to be described below are as follows. Unless otherwise described below, the SN of the RLC PDU means the extended RLC SN proposed above.

V [Delivered]: The largest value of the SNs of the RLC PDUs delivered to the reconfiguration buffer 434, and is referred to as V [D].

S [Not Received]: An SN set of RLC PDUs (hereinafter referred to as "lost PDUs") first lost from either the primary link or the secondary link, and then referred to as S [NR]. The S [NR] is initially initialized to an empty set. Thereafter, if a lost PDU occurs from the primary link or the secondary link, it is checked whether the lost PDU has been delivered to the reconfiguration buffer 434 before that time. If it was never delivered to the reconfiguration buffer 434, the SN of the lost PDU is registered in S [NR]. However, if it was previously delivered to a higher layer, the lost PDU is ignored. On the other hand, if the SN of the lost PDU is already registered in S [NR], the SN of the lost PDU is erased in S [NR] as it is a lost RLC PDU on both primary and secondary links. Finally, if an RLC PDU having an SN registered in S [NR] is normally received over the remaining link, the SN of the normally received RLC PDU is erased in S [NR].

S [Missing]: An SN set of RLC PDUs that are both lost and not normally received on either the primary link or the secondary link, hereinafter referred to as S [M]. That is, the SN of the RLC PDU registered in the S [M] is an SN lost in both the primary link and the secondary link and erased in S [NR].

Looking at the operation of the redundancy check unit 432 using the defined variables as follows.

When the redundancy checker 432 receives the first PDU through the newly configured secondary link, the redundancy checker 432 initializes V [D] with the SN of the RLC PDU most recently received from the primary link and delivered to the reconfiguration buffer 424. Initialization of the V [D] is not performed by a separate procedure, and V [D] is the highest SN among SNs of RLC PDUs received through the primary link and delivered to a higher layer before the secondary link is configured. You can also update. The redundancy checker 432 then compares the SN of the RLC PDU first received over the secondary link with the SN recorded in the V [D]. If the SN of the RLC PDU is larger than the SN recorded in the V [D], the RLC PDU is transferred to the reconfiguration buffer 424. At this time, the V [D] is updated to the SN of the RLC PDU delivered to the reconstruction buffer 424. The redundancy checker 432 then performs the same operation when an RLC PDU having an SN greater than the SN recorded in the V [D] is received through the primary link and the secondary link.

However, the redundancy checker 432 determines that the SN of the first RLC PDU received through the secondary link or subsequent RLC PDU received through the primary link or the secondary link is equal to or smaller than the SN recorded in V (D). Check it. If the SN of the RLC PDU is equal to or less than the SN recorded in the V [D], the duplicate detection unit 432 checks whether there is an SN that matches the SN of the RLC PDU as an element of S [NR]. If not present in the S [NR], the duplicate detection unit 432 determines that duplicate reception and discards the RLC PDU. This is a case where the same RLC PDU is repeatedly received through the primary link and the secondary link. However, if the SN of the RLC PDU is present as an element in the S [NR], the redundancy checker 432 transfers the RLC PDU to the reconstruction buffer 434. And SN of the RLC PDU existing as an element in S [NR]. This corresponds to a case where the RLC PDU is previously lost on either the primary link or the secondary link, but the lost PDU is received on the remaining link.

Meanwhile, when the lost PDU is generated through the primary link or the secondary link, the redundancy checker 432 checks whether the SN of the lost PDU exists as an element of the S [NR]. If the SN of the lost PDU exists as an element in the S [NR], the redundancy check unit 432 deletes the SN of the lost PDU from the S [NR]. In addition, the SN of the lost PDU is registered as an element of S [M], and the SN registered as an element of S [M] is notified to the reconstruction buffer 434 for reference in reconstructing the received RLC PDUs. Make sure Meanwhile, the redundancy checker 432 removes the SN notified to the reconstruction buffer 434 from the S [M]. This is the case when the corresponding RLC PDU is lost on both the primary link and the secondary link. However, if the SN of the lost PDU does not exist as an element of S [NR], the redundancy check unit 432 registers the SN of the lost PDU as an element of S [NR].

The redundancy checker 432 considers a corresponding RLC PDU to be lost for the following situations.

First, when there is a situation where the difference between the SN of the RLC PDU received at an arbitrary time point per link and the SN of the immediately received RLC PDU is 1 or more, the RLC PDU having an unreceived SN is regarded as a lost PDU. To this end, the SN of the previously received RLC PDU must be managed for each link. For example, if an RLC PDU having 13 as an SN is received from the primary link at any time, but the SN of the immediately preceding RLC PDU is 10, the RLC PDUs having 11 and 12 as SN are regarded as unreceived PDUs. Meanwhile, as another example, a method of managing an SN of an RLC PDU to be received may also be proposed. For example, if an RLC PDU having a SN of 10 is received from a primary link at any point in time, but the SNs of consecutive RLC PDUs received are 13, the RLC PDUs having 11 and 12 as SNs may be regarded as unreceived PDUs. .

Secondly, when the first RLC PDU is received on the secondary link, the missing PDU can be identified by considering both the primary link and the secondary link. That is, when the SN of the RLC PDU first received on the secondary link after V (D) is initialized is larger than the initial value of V (D), between the initial value of V (D) and the SN of the first RLC PDU. An RLC PDU with an existing SN is considered a missing PDU. For example, if V (D) is initialized to 5, and the SN of the first RLC PDU received on the secondary link is 10, the RLC PDUs with 6, 7, 8, and 9 as SN are regarded as lost PDUs. . The situation is that the secondary link is transmitted 5 RLC PDUs ahead of the primary link. However, if the difference between the initial value of the V (D) and the SN of the first RLC PDU of the secondary link is less than 1, it is assumed that no lost PDU has occurred.

Example of the behavior of the reconfiguration buffer

The reconfiguration buffer 434 according to an embodiment of the present invention reconfigures the RLC PDUs delivered from the redundancy checker 432 in SN order and delivers the RLC PDUs to a higher layer by a predetermined rule. Specifically, the operation of the reconfiguration buffer 434 will be described. The reconfiguration buffer 434 stores the RLC PDUs transmitted from the redundancy checker 432 in the order of SN. Then, check the SNs of the stored RLC PDUs. The check considers missing PDUs for the gap of the SN. The reconfiguration buffer 434 stores the smallest SN among the SNs of the lost RLC PDUs in a variable called V (First Gap). When the first gap is determined, the reconfiguration buffer 434 transfers RLC PDUs having an SN smaller than the first gap to a higher layer. When delivery of the targeted RLC PDU is made, the reconfiguration buffer 434 updates the V (First Gap) with a new SN. The update of the first gap applies the same criteria as described above. When the first gap is updated, the reconfiguration buffer 434 transfers RLC PDUs having an SN smaller than the updated first gap to an upper layer. The update of the first gap is limited to the case where an RLC PDU corresponding to V (First Gap) is received and an RLC PDU corresponding to V (First Gap) is notified as the final unreceived PDU.

As described above, in the present invention, the redundancy checker transfers only one duplicated RLC PDUs among the RLC PDUs received from the primary link and the secondary link to the reconfiguration buffer, and discards the remaining received RLC PDUs. The redundancy checker also determines the last lost PDU and notifies the reconstruction buffer. The reconfiguration buffer is delivered to the upper layer when the order of the RLC PDUs delivered by the redundancy checker is correct, thereby obtaining a selective combining gain without affecting the operation of the RLC layer.

Example of Selective Combination

5 is a diagram illustrating an example of an operation of a selective combiner of a UE performing selective combining according to an embodiment of the present invention. In this case, the RLC PDUs having 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 as SNs are sequentially received at the reception points T (1) to T (9). I assume. Assume that RLC PDUs with SNs of 15, 16, 17, 18, 19, 20, 21, 22, 23, and 24 are sequentially received at the reception points T (1) through T (9), respectively. Doing. On the other hand, it is assumed that a secondary link is set at an arbitrary time T (0), and V (D) is initialized to 10 at this time.

Referring to FIG. 5, the redundancy check unit 432 receives a PDU having a SN of 11 (hereinafter referred to as “SN 11”) through the primary link to the T 1, and has an SN of 15 through the secondary link. Receive a PDU (hereinafter referred to as "SN 15"). Thereafter, the redundancy checker 432 updates V [D] to 15, and registers 12, 13, and 14, which are SNs existing between SN 11 and SN 15, to S [NR]. The SN 11 and the SN 15 are transferred to the reconfiguration buffer 434. The reconfiguration buffer 434 sets V (First Gap) to 12 and delivers SN 11, which is an RLC PDU having an SN lower than V (FIRST GAP), to the RLC layer.

At any point in time T (2), the redundancy check section 432 receives the SN 12 on the primary link and the SN 16 on the secondary link. The redundancy check unit 432 updates the V [D] to 16 based on the SN received through the secondary link, and selects 12 which is an element of the S [NR] based on the SN received through the primary link. Delete it. The SN 12 and the SN 16 are transferred to the reconstruction buffer 434. The reconfiguration buffer 434 updates the V (FIRST GAP) to 13 and forwards the SN 12 to a higher layer.

At any time point T (3), the redundancy check unit 432 receives the SN 13 on the primary link and the SN 17 on the secondary link. The redundancy checker 432 updates the V [D] to 17 based on the SN received through the secondary link, and selects 13 which is an element of the S [NR] based on the SN received through the primary link. Delete it. The SN 13 and the SN 17 are transferred to the reconstruction buffer 434. The reconfiguration buffer 434 updates the V (FIRST GAP) to 14 and delivers the SN 13 to a higher layer.

At any time point T (4), the redundancy check unit 432 receives the SN 14 on the primary link and does not receive an RLC PDU on the secondary link. The redundancy check unit 432 maintains V (D) at 17 and deletes 14, which is an element of S [NR], based on the SN received through the primary link. The SN 14 is then transferred to the reconstruction buffer 434. The reconstruction buffer 434 updates the V (FIRST GAP) to 18 and transfers the SN 14, the SN 15, the SN 16, and the SN 17 to a higher layer.

At any point in time T 5, the redundancy check unit 432 receives the SN 15 over the primary link and the SN 19 over the secondary link. The redundancy checker 432 updates the V (D) to 19 based on the SN received through the secondary link, and adds 18 to the S [NR] based on the SN received from the T (4). Register. Since the SN of the SN 15 received through the primary link is smaller than the V (D) and not an element of the S [NR], it may be determined that the received SN is a duplicated RLC PDU. Therefore, the redundancy checker 432 discards the SN 15 without being transferred to the reconstruction buffer 434. The SN 19 is delivered to the reconstruction buffer 434. The SN 19 is stored in the reconstruction buffer 434 until the SN 18 corresponding to the V (FIRST GAP) is received.

At any time point T 6, the redundancy check unit 432 does not receive an RLC PDU on the primary link, but receives an SN 20 on the secondary link. The redundancy checker 432 updates the V (D) to 20 based on the SN received through the secondary link, and the SN 20 is transferred to the reconstruction buffer 434.

At any point in time T 7, the redundancy check unit 432 receives the SN 17 over the primary link and the SN 21 over the secondary link. The redundancy checker 432 updates the V (D) to 21 based on the SN received through the secondary link, and discards the SN 17 as a duplicately received RLC PDU. The SN 21 passes to the reconstruction buffer 434. The redundancy checker 432 confirms that the SN 16 is a lost PDU at T (7). However, since the SN 16 has already been received over the secondary link and delivered to the higher layer, it is discarded without being registered in the S [NR].

At any point in time T 8, the redundancy check unit 432 does not receive any RLC PDUs on the primary and secondary links.

At any point in time T 9, the redundancy check unit 432 receives the SN 19 over the primary link and the SN 23 over the secondary link. The redundancy checker 432 updates V (D) to 23 based on the SN received through the secondary link, and discards the SN 19 received through the primary link as it has already been delivered to a higher layer. . The SN 23 is delivered to and stored in the reconstruction buffer 434. On the other hand, based on the SN received through the primary link to the T (9), it is confirmed that the SN (18) is a lost PDU. Since the SN 18 is already registered in S [NR] at that time, the 18 is removed from S [NR] and 18 is registered in S [M] as a new element. The redundancy checker 432 notifies the reconstruction buffer 434 that a new element is registered in S [M], so that the RLC PDU with SN 18 is the last lost PDU. And 18 registered in S [M]. The reconfiguration buffer 434 updates the V (FIRST GAP) to 22, which is the location of the next lost PDU by being informed that the SN 18 is the last lost PDU, and SNs which are RLC PDUs having SNs earlier than 22. (19), the SN 20 and the SN 21 are transmitted to the upper layer.

B. Other Embodiments

Hereinafter, as another embodiment of the present invention, we propose a selective combining method in the case of using the outer coding scheme for MBMS service.

To this end, in the detailed description to be described later, the hierarchical structure and the outer coding / decoding for supporting the outer coding scheme will be outlined, and then the selective combining method according to another embodiment of the present invention will be described in detail.

1. Hierarchy

Prior to proposing the present invention, a method of using outer coding has been proposed as one of methods for reducing forward transmission power in an MBMS service. The outer coding is a technique of increasing coding gain by applying channel coding to data to be transmitted repeatedly. In order to perform the outer coding, a new layer called forward error correction (FEC) is required.

6 illustrates a protocol structure of a network and a terminal when the FEC layer is introduced.

Referring to FIG. 6, the FEC layer 605 of a network located in an RNC divides or concatenates data transmitted from an upper layer to an appropriate size, and inserts a serial number for each data block and temporarily stores the data. The FEC layer 605 then transfers the data blocks to the RLC layer 610 through outer coding when as many data blocks as needed are accumulated in the buffer. If the FEC layer 605 does not exist, the RLC layer 610 adjusts the size of the data to an appropriate size and inserts a serial number. However, if the FEC layer 605 has already performed the operation, the RLC layer 610 does not perform this operation. That is, the data received from the FEC layer 605 is transferred to the MAC layer 615. The data processed by the MAC layer 615 is transferred to the physical layer 620 again, and the physical layer 620 performs channel coding on the received data once again, and then transmits the data to the terminal through a wireless channel. .

Meanwhile, the physical layer 625 of the terminal processes the received signal and delivers it to the MAC layer 630. The MAC layer 630 processes the received data and transfers the received data to the RLC layer 635. When the FEC layer 640 is used, the RLC layer 635 takes no action and thus transfers the data to the FEC layer 640. The FEC layer 640 examines the serial number of the received data and performs channel decoding. The channel decoding performed at this time corresponds to the outer decoding corresponding to the outer coding.

As described above, when the FEC layer is used, the layer assigning and confirming the serial number used for selective combining becomes the FEC layer, not the RLC layer. Therefore, it is necessary to slightly change the structure presented in the first embodiment of the present invention. That is, the UE must perform a selective combining operation using the FEC SN of the FEC, and the selective combiner is present between the RLC layer and the FEC layer. A second embodiment of the present invention will be described in more detail with reference to FIG. 8.

2. Outer Coding / Decoding

Hereinafter, an outer coding and decoding technique performed by adding an FEC layer will be described in an embodiment of the present invention. In the following description, the outer coding is performed in a network, that is, RNC, and the outer decoding is performed by a terminal.

7 is a diagram for schematically describing outer coding and outer decoding.

In a typical wireless communication system, channel coding is performed at the physical layer, but if coding is performed at a separate layer once more, a stronger coding gain can be obtained. This is called outer coding. In addition, the receiving side performs decoding more efficiently using a method called erasure decoding. This is called outer decoding.

Hereinafter, the outer coding and the outer decoding will be described in more detail with reference to FIG. 7.

The layer in charge of the outer coding on the transmitting side is composed of k data blocks 705 to 720 having the same size of data transmitted from the upper layer. And (n, k) coding is performed on each column of the k data blocks separately. That is, (n, k) coding is performed on bits of the same position of each data block. As a result, (n-k) parity blocks (data blocks consisting only of parity bits) 725-730 are generated. The physical layer of the transmitter performs channel coding on the n data blocks (k systematic blocks and nk parity blocks) 705 to 730 individually, performs a CRC operation, and then receives the received data. To the side.

The physical layer on the receiving side performs channel decoding on the data blocks received from the transmitting side, and discards the data blocks in error through the CRC operation. For example, if an error occurs in the second data block 710, the data block 710 is discarded in the physical layer. The physical layer transfers the blocks that pass the CRC test to the layer responsible for the outer decoding, and discards the blocks that do not pass the CRC test. The layer in charge of the outer decoding at the receiving side reconstructs the received blocks into the original n blocks 750 to 775. Also, blocks discarded because they do not pass the CRC test are regarded as erase bits. For example, if the second and sixth blocks did not pass the CRC test, the blocks are considered erasure bits. That is, the outer decoder considers the code words in the second and sixth positions as erase bits. The erasure bits are bits in which an error occurs in the transmission process and whose value cannot be determined. The outer decoder can perform the outer decoding more efficiently by identifying the exact positions of the erase bits. For example, in the case of a Reed Solman (RS) code of (16, 12), if the decoder correctly locates the erase bits, the error of 4 bits is corrected. On the other hand, if the decoder does not know the location of the erase bits correctly, it can correct only one or two bits of error. Hereinafter, decoding that accurately knows and performs the position of erase bits is called erasure decoding. The erasure decoding scheme is used in the outer coding and the outer decoding proposed to support the MBMS service. To this end, each data block is assigned a serial number in a layer for performing outer coding. The serial number is assigned in the FEC layer, and is expected to have a 7 bit size similar to the RLC serial number in the first embodiment of the present invention.

When the receiver in charge of the outer decoding performs the outer decoding, the layer performs the error correction operation through the outer decoding on each column of each data block. The situation in which the outer decoding can be performed corresponds to a situation in which k original data blocks and n-k parity blocks are both received. The error corrected data blocks are delivered to a higher layer.

The outer coding and outer decoding operations will be described below with reference to an example. It is assumed that (16, 12) RS coding is used, and the size of each data block is assumed to be 100 bits.

1. Outer coding layer at the sender: Wait until 1200 bits of data arrive from the upper layer.

2. Transmitter outer coding layer: reconstructs 1200 bits into 12 100 bit blocks.

3. Transmitter Outer Coding Layer: Perform (16,12) RS coding on bits in the same location of each block with respect to columns.

4. Transmitter Outer Coding Layer: As a result of operation 3, four parity blocks of 100 bits are newly created.

5. Sender outer coding layer: inserts serial number information into the original data block and parity blocks and forwards it to the physical layer.

6. Transmit physical layer: performs channel coding and CRC operation on each block.

7. Transmit physical layer: Radio channel transmission.

8. Receive physical layer: performs channel decoding and CRC operation on the received blocks.

9. Receive side physical layer: Pass the blocks that passed the CRC test to the upper layer and discard the failed blocks.

10. Outer side decoding layer: interprets the serial number of blocks delivered by the physical layer.

11. Receive side outer decoding layer: rearranges each block in order, replacing blocks that are lost during transmission with erase bits.

12. Receive side outer decoding layer: perform (16,12) RS decoding operation on each column of blocks.

13. Receive side outer decoding layer: 1200 bits of error-corrected data as a result of operation 12 are transmitted to the upper layer.

For reference, in the above-described operation, if the number of erase bit blocks exceeds a certain number, decoding is impossible. In this case, the data is transferred directly to the upper layer without decoding.

B-1. Second embodiment

8 is a diagram illustrating the structure of a UE for performing another embodiment of the present invention. The structure of the UE shown in FIG. 8 assumes a situation where an optional combiner is configured for selective combining. However, since only the primary link with the serving cell exists, only a configuration of processing a signal received from the serving cell will exist in a situation in which selective coupling is not performed. Therefore, the structure of the UE consists of only the main link 810 composed of the physical layer 812, the MAC layer 814, and the RLC layer 816, and the FEC layer 840 only. Thereafter, when a new MBMS service provided from the serving cell is to be newly provided from a target cell, the UE configures a secondary link with the target cell. The structure of the UE configured with the secondary link is shown in FIG. 8.

Referring to FIG. 8, the UE obtains physical layer information, MAC layer information, and RLC layer information from the target cell to which the secondary link is to be configured through the MCCH. Thereafter, a new physical layer 822 is set by the physical layer information, and a new MAC layer 824 is set by the MAC layer information. A new RLC layer 826 is set based on the RLC layer information. The configuration of the physical layer 822, the MAC layer 824, and the RLC layer 826 means that a new secondary link 820 is established. The UE then sets up an optional combiner 830 in accordance with the present invention. Thereafter, the selective combiner 830 and the primary link 810 and the secondary link 820 are connected to the lower layer, and the selective combiner 430 and the FEC layer 840 are connected to the upper layer.

The optional combiner 830 includes a duplication checker 832 and a reordering buffer 834. The selective combiner 830 discards the duplicated FEC PDUs among the FEC PDUs received through the primary link 810 and the secondary link 820, and re-executes the duplicated FEC PDUs in the order of transmission. It is configured to deliver to the FEC layer (840). That is, the same FEC PDU may be received through the primary link 810 and the secondary link 820. In this case, the redundancy checker 832 constituting the selective combiner 830 discards one of the FEC PDUs received through the primary link 810 and the FEC PDUs received through the secondary link 820 and the other one. Outputs only FEC PDUs. Meanwhile, the FEC PDUs output from the redundancy checker 832 may not be regarded as having the same order as the transmission order. Accordingly, the FEC PDUs output from the redundancy checker 832 are temporarily stored in the reconfiguration buffer 834, and then reconfigured and forwarded to the FEC layer 840 in the transmission order.

In order to confirm whether the redundancy checker 832 overlaps the FEC PDU provided from the primary link 810 and the FEC PDU provided from the secondary link 820, separate information is required. As an example of the information, the FEC SN that the FEC PDU has may be used. However, since the FEC SNs are the same, it is not necessarily assumed that they are duplicate FEC PDUs. The reason is that the FEC SN is given with a predetermined period. When the FEC PDU provided through the primary link 810 and the FEC PDU provided through the secondary link 820 have a delay difference of one period or more, The two FEC PDUs cannot be regarded as duplicates. This can be confirmed with the FEC SN version. As defined above, the FEC SN version is a value changed by the period. Therefore, even if the FEC SNs are the same, if the FEC SN versions are different, it may not be determined as a duplicate FEC PDU. In order to solve this problem, the present invention proposes an extended FEC SN as an additional information for identifying the duplication. The extended FEC SN is defined as in Equation 2 below.

Extended FEC SN_x = [FEC SN Version_x II FEC SN_x]

As shown in Equation 2, the extended FEC SN_x of the FEC PDU provided through the link x is a value obtained by concatenating the FEC SN version (FEC SN version_x) and the FEC SN (FEC SN_x) corresponding to the link x. . For example, if the FEC SN version of the primary link is "001" and the SN of the FEC PDU received on the primary link is "0000111", then the extended FEC SN is "0010000111".

Accordingly, the redundancy checker 832 obtains the extended FEC SNs for each of the FEC PDUs provided from the primary link 810 and the FEC PDUs provided from the secondary link 820, and compares the expanded FEC SNs. You can check whether or not. However, it does not replace the SN of FEC PDUs with the extended FEC SN. The extended FEC SN is used only to determine the front-rear relationship between the FEC PDUs received from the primary link 810 and the secondary link 820.

On the other hand, the FEC SN version is a value managed by the FEC layer of the network, like the RLC SN version in the first embodiment of the present invention, and is provided for each FEC PDU. The FEC SN version is incremented by 1 each time the FEC SN value returns from 127 to zero. Through the MCCH configured for each cell, the FEC SN version value of the FEC PDU transmitted at the corresponding time point is broadcast.

The redundancy checker 832 and the reconstruction buffer 834 in the second embodiment of the present invention described above are essentially identical to the redundancy checker 432 and the reconstruction buffer 434 in the first embodiment of the present invention. Do the same. However, the first embodiment uses an RLC SN but the second embodiment uses a FEC SN. That is, as in the first embodiment, in the second embodiment, the redundancy check unit and the reconstruction buffer can be operated using V [D], V [FG], S [NR], and S [M]. However, in the second embodiment, the difference is that the FEC SN is used to manage the variables. Therefore, in the operation of the redundancy check unit and the reconfiguration buffer in the second embodiment, the RLC PDU is replaced with the FEC PDU, the RLC SN is replaced with the FEC SN, and the extended RLC SN is replaced with the extended FEC SN in the operations described in the first embodiment. Exactly matches

B-2. Third embodiment

The first and second embodiments of the present invention describe the operation of the UE and the operation of the network in the case where there are entities for constructing data to be selectively combined in an appropriate size and providing serial numbers for each cell. The entity for assigning serial numbers after configuring data to an appropriate size was the RLC layer in the first embodiment and the FEC layer in the second embodiment. For convenience of explanation, an entity for assigning a serial number after configuring data to an appropriate size is referred to as a serial number assigning device.

From the network's point of view, another way to provide selective combining is to configure only one serial numbering device and allow the cells to share the device to allow selective combining. As described above, a network managing a RLC SN version or a FEC SN version is provided in a situation in which multiple cells share a single serial numbering device. For reference, the operation of the UE for the case where the serial number assigning device is configured for each cell and the case where several cells share the same serial number assigning device is the same. Therefore, the description to be described later is limited to the operation of the network.

9 shows an example of a network in which only one serial number assigning device is configured. For example, any MBMS service is provided to Cell 1 915-1, Cell 2 915-2, Cell 3 915-3, Cell 4 915-4, and Cell 5 915-5. In order to provide the MBMS service, the RNC configures one serial number assigning device 905 and storage devices 910-1, 910-2, 910-3, 910-4, and 910-5 for each cell. It was.

As described above, the serial number assigning device may be an FEC layer or an RLC layer depending on the presence or absence of the FEC layer. That is, when the FEC layer is configured as in the second embodiment, the FEC layer serves as a serial number assigning device. When the FEC layer is not configured as in the first embodiment, the RLC layer serves as a serial number assigning device. In the serial number assigning device, data assigned with serial numbers is individually transmitted for each cell. At this time, before being transmitted to each cell, it is stored in the storage device. As described above, the entity storing data before being transmitted for each cell may be a MAC layer in the first embodiment and an RLC layer in the second embodiment. Data stored in the storage device is transmitted cell by cell at an appropriate time. Therefore, even though the serial numbers are assigned through one serial number assigning device, the transmission time may be different for each cell.

As shown in FIG. 9, when one serial number providing device provides data to multiple storage devices, RLC SN version or FEC SN version information is managed in a storage device configured for each cell as follows.

First, a storage device providing data to any cell initially sets the RLC SN version or the FEC SN version to zero. The storage device then stores the number of PDUs transmitted to the cell in a variable called N (PDU). The N (PDU) increases monotonically between 0 and 127, and then returns to zero after 127. If the FEC SN or RLC SN has a different size, the size of N (PDU) is adjusted accordingly. As soon as the N (PDU) becomes 0 at 127, the storage device increments the RLC SN version or the FEC SN version by one. That is, the RLC SN version or FEC SN version is incremented by one when N (PDU) returns to 0 from the maximum value. The storage device periodically transmits the RLC SN version or the FEC SN version on the MCCH.

The selective combining operation is established only in cells where the serial numbering device is the same. However, the current standard does not define a method by which a UE can know which serial numbering device receives a cell. Therefore, the present invention defines a new parameter, called a serial number identifier, and proposes a method in which the parameter is transmitted periodically for each cell.

FIG. 10 shows an example of a network in which a serial number assigning device is configured, and shows an example of periodically transmitting the serial number assigning device identifier for each cell.

Referring to FIG. 10, any serial number assigning device 1005-1 provides data to cell 1 1015-1, cell 2 1015-2, and cell 3 1015-3, and another serial number. The numbering device 1005-2 provides data to cells 4 1015-4 and 51010-5. The network assigns unique identifiers to the serial numbering devices 1005-1 and 1005-2. At this time, the identifier assigned to the serial numbering device should not overlap with the identifiers assigned to the peripheral serial numbering device. For example, the size of the serial number identifier may be about 5 bits. An operation of assigning an identifier to each serial number assigning device 1005-1 or 1005-2 may be performed by an operator using O & M.

The network periodically transmits the serial number identifiers for each cell, thereby allowing the UE to determine whether to perform selective association. For example, when UE # 1 1020-1 recognizes that the serial number assigning device identifier of cell 1 1015-1 and the serial number identifier of cell 3 1015-3 are the same, the cell 1 1015. -1) or attempt to selectively combine by setting the secondary link to the cell 3 (1015-3). If UE # 2 1020-2 recognizes that the serial number identifier of cell 3 1015-3 and the serial number identifier of cell 4 1015-4 are different from each other, UE # 2 1020-2 does not attempt selective combining. . That is, a UE moving between cells assigned serial numbers by different serial number assigning devices does not perform the selective combining proposed by the present invention. However, for a UE moving between cells assigned a serial number by the same serial number assigning device, the selective combining proposed in the present invention is performed.

FIG. 11 is a diagram illustrating a control flow according to operation of a UE in a network having the structure of FIG. 10. The operation of the UE according to FIG. 11 is essentially the same as the operation of the UE according to the first embodiment described with reference to FIG. 3. However, in determining whether the UE performs selective combining, it will be said that there is a difference in referring to whether the serial number identifier of the target cell matches the serial number identifier of the serving cell. The control flow of FIG. 11 assumes a situation in which a radio link is established between a UE and a serving cell and a specific MBMS service is provided through the radio link.

Referring to FIG. 11, in step 1101, the UE receives a signal from neighbor cells and detects whether a good signal among the received signals exists. The definition that the received signal is good can be made in various ways. For example, as a method of using the received signal strength, if the received signal intensity exceeds a predetermined threshold, it may be determined that the signal is good. The presence of the good signal implies that the UE is in close proximity to any target cell that transmitted the good signal. Accordingly, the UE can simultaneously receive signals from the serving cell and the target cell. Meanwhile, the target cell may be one or more cells.

Assuming that there are a plurality of target cells, the UE receives the MCCH from the target cell in which the best signal is received in step 1103. Through the MCCH, identifiers of the MBMS service provided by the target cell, radio bearer information of the provided MBMS service, selective coupling assistance data, and the like are transmitted. The UE checks the information received through the MCCH and proceeds to step 1105. In step 1105, the UE checks whether the desired MBMS service is provided by the target cell. If the desired MBMS service is provided, the process proceeds to step 1107. Otherwise, if the desired MBMS service is not provided, the process proceeds to step 1109.

In step 1107, the UE determines whether the target cell supports selective combining based on the SC identifier among the checked selective combining assistance data. If it is determined by the SC identifier that the target cell supports selective combining, the process proceeds to step 1111. Otherwise, if it is determined that the target cell does not support selective combining, the process proceeds to step 1109.

In step 1111, the UE compares the serial number identifier obtained from the serving cell with the serial number identifier obtained from the target cell. If the serial number identifier obtained from the serving cell and the serial number assigning device identifier obtained from the target cell are the same by the comparison, the process proceeds to step 1113. Otherwise, if the serial number assigning device identifiers from the target cell and the serving cell do not match, the process proceeds to step 1109.

When the UE proceeds to step 1109, the UE returns to step 1105 after confirming the information received through the MCCH from the target cell in which a good signal is received. However, if the UE proceeds to step 1113, the UE establishes a radio link, that is, a secondary link, with the target cell in order to receive the desired MBMS service. The secondary link is established by radio bearer information received through the MCCH. The radio bearer information includes physical layer information, MAC layer information, and the like. The physical layer information is information about a transport channel, and includes code information corresponding to a physical channel, a type of channel coding applied to a physical channel, a channel coding rate, a transmission time interval (TTI), and the like. The MAC layer information includes multiplexing information according to whether multiplexing is applied in the MAC layer and service identifier information according to whether a service identifier is used in the MAC layer. The UE sets a new physical layer by the physical layer information, and sets a new MAC layer by the MAC layer information. The secondary link refers to the newly configured physical layer and MAC layer.

If the configuration of the secondary link is completed as described above, the UE configures an optional combiner for selective combining in step 1115. Thereafter, the selective combiner is connected to the primary link with the serving cell and the secondary link with the target cell, and performs selective combining on broadcast data received through the primary link and the secondary link.

In step 1117, the UE continuously monitors whether a situation in which the release of the primary link or the secondary link is required occurs. The situation in which the release is required corresponds to a situation in which a signal having an intensity less than a predetermined threshold is received. If such a situation is detected, the UE releases the link with the corresponding cell. For example, if the desired signal is not received through the primary link, the primary link established with the serving cell is released. Otherwise, if a desired signal is not received through the auxiliary link, the auxiliary link established with the target cell is released. If only one link exists in step 1117, the UE terminates the selective combining operation by releasing the selective combiner configured in step 1119.

B-3. Fourth embodiment

12 is a diagram showing the structure of a UE for performing another embodiment of the present invention. The structure of the UE shown in FIG. 12 assumes a situation where an optional combiner is configured for selective combining when receiving data from two or more links. Here, selective combining is a technique for receiving data through multiple cells (or links) to reduce the possibility of data loss. Therefore, how many cells (or links) the terminal receives data does not have an essential effect on the operation of the terminal. However, for convenience of description, it is assumed that the data is received from only two cells.

Referring to FIG. 12, the optional combiner 1220 includes a duplication checker 1215 and a reordering buffer 1210, and the duplication checker 1215 includes a plurality of links. Fields 1225 and 1230. The reordering buffer 1210 is connected to a serial number assigning device 1205.

Specific Behavior of Selective Coupling at the UE

Hereinafter, the operations of the redundancy checker and the reconfiguration buffer for selective coupling in the UE according to an embodiment of the present invention will be described in detail.

Examples of variables managed by the duplicate checker

The duplication checker 1215 manages the following variables for each cell in which a link is established. In this case, the UE establishes a link with n cells, and names each cell as c_1 1225,..., And c_n 1230.

Variables managed by the duplicate checker 1215 for any cell x include the following.

VR (c_x): Serial number of the PDU expected to be received next from cell x. 1 is added to the serial number of the most recently received PDU from cell x.

VM (c_x): A set of serial numbers of unreceived PDUs from cell x.

On the other hand, the duplication checker 1215 manages the following variables in common for all cells.

VD: A set of serial numbers of PDUs that the duplication checker 1215 has delivered to the reordering buffer 1210. This is used for duplicate acknowledgments.

Highest_delivered_SN: Among the serial numbers of PDUs that the duplication checker 1215 has delivered to the reordering buffer 1210, it represents the highest serial number.

Permanently_missing_SN: A set of serial numbers of final unreceived PDUs.

Variables Managed by Reconfiguration Chopper

The reordering buffer 1210 manages the following variables.

First_missing_SN: The RB considers the RLC PDUs corresponding to the gap of the SN as unreceived RLC PDUs, of which the serial number of the unreceived PDU with the lowest serial number (or corresponding to the earliest occurrence of the earliest point in time) Is stored in the variable.

Example of operation of redundancy check unit

The duplication checker 1215 manages each variable and performs the duplication check as follows. Unlike the previous embodiment, it is assumed that the optional combiner 1220 is configured at the time the initial link is established. That is, it is assumed that the optional combiner 1220 is also configured when the UE configures a physical layer / MAC layer / RLC layer to receive MBMS service in any cell 1. In the previous embodiment, it is assumed that the UE moves to another cell 2 and establishes another link in cell 2 to configure the optional combiner 1220 when there is more than one link. The difference derived from the two situations is the initialization operation of the V (D) variable or Highest_delivered_SN. In other words, if the optional combiner is present even in a single link situation, the initialization of V (D) described in the previous embodiment is not necessary.

1. The duplication checker 1215 receives the PDU from any cell x.

2. The duplication checker 1215 compares the serial number of the received PDU with VR (c_x).

3. If the serial number of the received PDU is larger than VR (c_x), proceed to 4; if the same, skip 4 and proceed to 5.

4. The duplication checker 1215 adds serial numbers corresponding to the serial number of the received PDU and the VR (c_x) to the VM (c_x). The serial number to be included in the VM (c_x) also includes VR (c_x).

5. The duplication checker 1215 updates the serial number of the PDU which received the VR (c_x) by adding 1 to it.

6. The duplication checker 1215 compares the serial number of the received PDU with Highest_delivered_SN. If Highest_delivered_SN is greater than the serial number of the received PDU, go to 7. If not, proceed to 11.

7. Update Highest_delivered_SN with the serial number of the received PDU.

8. The received PDU is transferred to the reconfiguration buffer 1210.

9. Add the serial number of the delivered PDU to the VD.

10. End the process and wait for the next PDU to be received.

11. Check that the serial number of the received PDU is included in the VD. If the serial number of the received PDU is included in the VD, the process proceeds to 12. On the other hand, if the serial number of the received PDU is not included in the VD proceeds to 14.

12. Discard the received PDU.

13. End the process and wait for the next PDU to be received.

14. Deliver the received PDU to the RB.

15. Add the serial number of the delivered PDU to the VD.

16. End the process and wait for the next PDU to be received.

On the other hand, the duplication checker 1215 manages the VM variable and checks the final unreceived PDU as follows.

1. The duplication checker 1215 monitors serial numbers stored in VM variables managed for each cell.

2. If a duplicate checker 1215 has any serial number stored in all VM variables, the duplicate checker 1215 stores the serial number in Permanently_missing_SN. For example, any UE is receiving PDUs from Cell 1, Cell 2, and Cell 3, VM (c_1) = [10, 15, 18], VM (c_2) = [10, 13, 15], VM ( c_3) = [10, 15], the serial numbers 10 and 15 are stored in Permanently_missing_SN.

3. The duplication checker 1215 reports the serial numbers stored in Permanently_missing_SN to the reordering buffer 1210.

4. The duplication checker 1215 removes the serial numbers reported to the reordering buffer 1210 from Permanently_missing_SN.

5. The duplication checker 1215 removes the serial numbers reported to the reordering buffer 1210 from the VM variables.

Example of the behavior of the reconfiguration buffer

In this case, the operation of the reordering buffer 1210 is as follows. The reordering buffer 1210 stores the PDUs delivered by the duplication checker 1215 in the serial number order, and considers the PDUs corresponding to the increment of the serial number equal to or greater than 1 as unreceived PDUs. . The operation of the reordering buffer 1210 will be described in more detail as follows.

1. The PDU delivered by the Duplication Checker 1215 arrives at the Reordering Buffer 1210.

2. Reordering Buffer 1210 stores the PDUs in order based on the serial number.

3. If the serial number of the received PDU is the same as First_missing_SN, it means that the PDU corresponding to First_missing_SN is no longer an unreceived PDU. Therefore, First_missing_SN is updated with the serial number of the unreceived PDU having the lowest serial number among the remaining unreceived PDUs.

4. Forward PDUs with serial numbers lower than the updated First_missing_SN to the upper layer.

5. When the DC reports the serial numbers of the final unreceived PDUs, the reordering buffer 1210 considers that the unreceived PDUs corresponding to the serial numbers have been received.

6. If one of the serial numbers of the last unreceived PDUs matches First_missing_SN, it means that the PDU corresponding to First_missing_SN is no longer an unreceived PDU. Therefore, First_missing_SN is updated with the serial number of the unreceived PDU having the lowest serial number among the remaining unreceived PDUs.

7. Pass PDUs with serial numbers lower than the updated First_missing_SN to the upper layer.

B-4. Fifth Embodiment

The fifth embodiment of the present invention provides an operation of a selective combiner that implements the functions of a re-ordering buffer and a duplication check.

UE structure

FIG. 13 is a diagram illustrating a RLC structure of a UE when a selective coupling function is included in an RLC entity according to a fifth embodiment of the present invention.

Referring to FIG. 13, the selective combiner 1335 receives RLC PDUs from a plurality of cells through a lower layer. The RLC PDUs duplicated from the RLC PDUs are discarded and the remaining RLC PDUs are reconstructed. The reconstructed RLC PDUs forward to the RLC layer 1330.

The selective combiner 1335 manages the SCR-window to perform the above-described operation. Meanwhile, the SCR-window identifies a front and rear relationship between RLC PDUs received from various cells and manages RLC PDUs stored in a re-ordering buffer. In order to perform the operation of the re-ordering buffer, the SCR-window manages variables next_expect_SN and ScrWindow_UpperEdge.

Structure and Operation Example of SCR-window

14 shows the structure of the SCR-window.

Referring to FIG. 14, the SCR-window 1465 includes an ScrWindow_UpperEdge 1450 and an SCR_WINDOW_SIZE 1455.

The ScrWindow_UpperEdge 1450 means the highest serial number among serial numbers of the RLC PDUs received by the UE up to the present time. Therefore, if the serial number of the newly received RLC PDU is higher than the existing ScrWindow_UpperEdge, the ScrWindow_UpperEdge is updated with the new serial number. That is, the ScrWindow_UpperEdge is updated with the serial number of the newly received RLC PDU.

The SCR_WINDOW_SIZE 1455 is a parameter set by the RNC and notified to the UEs. The SCR_WINDOW_SIZE 1455 means a maximum value of a transmission difference that may occur between two adjacent cells. If the RNC informs UEs by setting SCR_WINDOW_SIZE between any two cells to x, the RNC should ensure that the transmission difference between the two cells does not exceed x RLC PDUs.

The SCR-window 1465 is formed by an upper end point and a lower end point. In the SCR-window 1465, the ScrWindow_UpperEdge 1450 is an upward endpoint. Meanwhile, the downward end point is determined by a result of modulo operation of ScrWindow_UpperEdge SCR_WINDOW_SIZE to 128. The SCR-window 1465 proceeds in the same direction each time the ScrWindow_UpperEdge 1450 is updated.

If the serial number of the RLC PDU received at any point is located in the SCR-window, the serial number of the RLC PDU is considered to be smaller than ScrWindow_UpperEdge, and if the serial number of the RLC PDU is located outside the SCR-window, Is considered greater than ScrWindow_UpperEdge.

For example, suppose ScrWindow_UpperEdge is 100 and SCR_WINDOW_SIZE is 64 at any point in time.

At this point, the SCR-window has an upward endpoint of 100 and a downward endpoint of 36. The serial number 50 is located in the SCR-window when an RLC PDU having a serial number 50 arrives at any point after the point in time. Therefore, the serial number is smaller than 100, which is ScrWindow_UpperEdge.

In addition, when an RLC PDU having a serial number of 30 arrives at any point after the time, the serial number 30 is located outside the SCR-window. Therefore, the serial number is greater than 100, which is ScrWindow_UpperEdge. Therefore, the ScrWindow_UpperEdge is updated to 30, and the new downward end point of the SCR-window is 96, calculated as -34 by 128 modules.

On the other hand, if the RLC PDU with the serial number 120 arrives at any point after the point in time, the serial number 120 is located in the SCR-window, so the serial number 120 is smaller than ScrWindow_UpperEdge.

As described above, the SCR-window is a device that can determine whether the ScrWindow_UpperEdge moves with the update, and whether the serial number of the received RLC PDU is larger or smaller than the ScrWindow_UpperEdge. Also, only RLC PDUs with serial numbers on the SCR-window can be stored in the re-ordering buffer. For example, if the SCR-window is [downward endpoint = 0, upward endpoint = 64], only RLC PDUs with serial numbers between 0 and 64 are stored in the re-ordering buffer. As the SCR-window moves, the serial numbers of the RLC PDUs stored in the re-ordering buffer change.

Meanwhile, as another variable used in the optional combiner, next_expect_SN is a variable in which the serial number of the first unreceived PDU is stored among the unreceived PDUs. That is, it is the same variable as first_Gap of the previous invention. The initial value of the ScrWindow_UpperEdge is one less than the serial number of the RLC PDU initially received by the optional combiner. In addition, the initial value of the next_expect_SN is the serial number of the first RLC PDU received by the optional combiner.

Example of operation of the optional combiner

15 illustrates the operation of the selective coupler according to the fifth embodiment.

The operation of the selective combiner shown in FIG. 15 may include forming or changing a window (SCR_Window), storing broadcast data (RLC PDU) received by the window in a rearranged buffer, or transmitting the same to a higher layer; After updating the serial number (nex_expected_SN) of the unreceived broadcast data, the broadcast data stored in the rearrangement buffer is transferred to the upper layer.

Referring to FIG. 15, the optional combiner receives an arbitrary RLC PDU whose serial number is SN in step 1505. The selective combiner checks whether the serial number SN is located in the SCR-window in step 1507. If the SN is located in the SCR-window, the process proceeds to step 1525. If not, proceed to step 1510. The fact that the SN is not located in the SCR-window means that the SN is greater than ScrWindow_UpperEdge.

In step 1510, the selective combiner stores the previously received RLC PDU in a re-ordering buffer. The optional combiner then updates the ScrWindow_UpperEdge to the SN in step 1512. In step 1515, the optional combiner newly sets the SCR-Window by the updated ScrWindow_UpperEdge. That is, the SCR-window is updated by moving the downward end point of the SCR-window by the size moved by the ScrWindow_UpperEdge. For example, if ScrWindow_UpperEdge is 10 and SN is 15 in step 1507, the ScrWindow_UpperEdge is moved to 15 by 5. In addition, in step 1515, the lower end point also moves by five.

The selective combiner transfers RLC PDUs having a serial number outside the new SCR-window to higher layers among RLC PDUs stored in the re-ordering buffer in step 1417. For example, suppose the RLC PDU with the serial number 75 is stored in the re-ordering buffer. The serial number 75 was located in the window before the SCR-window moved (74 to 10). However, after the window is moved (79 to 15), it is located outside the window. Therefore, the RLC PDU is delivered to the RLC layer. Here, the RLC PDU of serial number 75 is stored in the re-ordering buffer, indicating that there is an unreceived RLC PDU before that. In addition, the fact that the serial number 75 is located outside the SCR-window means that there is no possibility of receiving the unreceived RLC PDU. Therefore, the unreceived PDU of the serial number 75 is delivered to the upper layer even though the sequence reconstruction is not completed.

The optional combiner checks whether next_expect_SN is located outside the SCR-window in step 1520. If next_expect_SN is located outside the SCR-window, the process proceeds to step 1560. Otherwise, if the next_expect_SN is located inside the SCR-window, the optional combiner proceeds to step 1495 and waits for the next RLC PDU to arrive.

The next_expect_SN located outside the SCR-window means that there is no possibility of receiving an unreceived RLC PDU corresponding to the next_expect_SN. Therefore, a new next_expect_SN should be set and RLC PDUs having a serial number smaller than the new next_expect_SN among the RLC PDUs stored in the re-ordering buffer should be delivered to the upper layer. Steps 1560 and 1565 are steps for the aforementioned operation.

In step 1560, the selective combiner updates next_expect_SN with the serial number of the first unreceived RLC PDU of the re-ordering buffer. For example, if there are unreceived RLC PDUs with serial numbers 100, 120, and 10 in the re-ordering buffer, update the serial number 100 with the new next_expect_SN.

Thereafter, the selective combiner proceeds to step 1565, and transmits RLC PDUs having a serial number smaller than the next_expect_SN to a higher layer. The RLC PDUs are RLC PDUs whose order has been successfully reconstructed. Once the delivery is complete, the optional combiner completes all processes in step 1595 and waits for a new RLC PDU to arrive.

However, if the SN is included in the SCR-window in step 1507, the flow proceeds to step 1525.

The selective combiner determines whether the PDU has been previously received in step 1525. This is possible by checking whether the SN of the PDU is already stored in the re-ordering buffer. That is, if an RLC PDU having a serial number SN is already stored in the re-ordering buffer, it means that the RLC PDU has been repeatedly received. In step 1540, the selective combiner discards the duplicated RLC PDU. The process proceeds to step 1595 to complete the process and waits for the next RLC PDU to arrive.

However, if the RLC PDU whose SN is the serial number is not stored in the re-ordering buffer, the RLC PDU is not duplicated. Therefore, the selective combiner proceeds to step 1530 to store the RLC PDU in the re-ordering buffer, and proceeds to step 1535.

In step 1535, the selective combiner checks whether the serial number of the RLC PDU is equal to next_expect_SN. If it is not the same, proceed to step 1595 to complete all processes and wait until the next RLC PDU arrives.

However, if the serial number of the received RLC PDU is the same as next_expect_SN, the flow proceeds to step 1545. In step 1545, the optional combiner updates next_expect_SN with the serial number of the first unreceived RLC PDU of the re-ordering buffer.

In operation 1550, the selective combiner delivers RLC PDUs having a serial number smaller than next_expect_SN to a higher layer. The RLC PDUs are RLC PDUs whose order has been successfully reconstructed.

After completing the step 1550, the selective combiner proceeds to step 1595 and finishes all processes and waits for the arrival of the next RLC PDU.

As described above, the present invention allows taking advantage of selective binding based on RLC SN and FEC SN, thereby taking advantage of the selective binding. Therefore, the UE has an effect of receiving a higher quality service from the same radio resource.

1 is a diagram showing a wireless access network structure in an asynchronous mobile communication system for applying an embodiment of the present invention.

2 illustrates signaling for providing selective combining assistance data according to an embodiment of the present invention.

3 is a diagram illustrating a control flow performed in a mobile terminal according to an embodiment of the present invention.

4 is a view showing the structure of a mobile terminal according to an embodiment of the present invention.

FIG. 5 shows an example of the operation of the select coupler in FIG. 4. FIG.

6 is a diagram illustrating a protocol structure of a network and a terminal when a forward error correction layer is introduced.

7 is a diagram for conceptually explaining outer coding / decoding.

8 is a view showing the structure of a mobile terminal according to another embodiment of the present invention.

9 is a diagram illustrating an example of a network in which only one serial number assigning device is configured to apply embodiments of the present invention.

10 is a diagram illustrating an example of a network including a plurality of serial number assigning devices for applying embodiments of the present invention.

FIG. 11 is a diagram illustrating a control flow according to operation of a UE in a network having the structure of FIG. 10. FIG.

12 is a view showing the structure of a mobile terminal according to another embodiment of the present invention.

13 is a view showing the structure of a radio link controller of a mobile terminal according to a fifth embodiment of the present invention;

14 is a view showing the structure of the SCR-window in FIG.

15 is a view showing the operation of the selective coupler according to the fifth embodiment of the present invention.

Claims (19)

A serving cell providing an arbitrary broadcast service through a mobile terminal, a primary link established by the mobile terminal, and a cell adjacent to the serving cell providing the arbitrary broadcast service through an auxiliary link established by the mobile terminal; In a mobile communication system including at least one target cell, and a wireless network controller for providing broadcast data according to the broadcast service to the serving cell and the target cell, the mobile terminal from the serving cell and the target cell In the method for selectively combining broadcast data, Receiving broadcast data from the serving cell and the target cell; Checking whether broadcast data is repeatedly received from the serving cell and the target cell; If the broadcast data is duplicated, only broadcast data received from one of the serving cell or the target cell is selected. Discarding broadcast data received from the remaining cells; And reconstructing the selected broadcast data by the order in which they are transmitted from the radio network controller through corresponding cells. The same extended sequence number as claimed in claim 1, wherein extended sequence numbers corresponding to each of broadcast data from the serving cell and extended sequence numbers corresponding to each of broadcast data from the target cell exist. And determining that broadcast data of the same extended sequence number has been repeatedly received. 3. The extended sequence number of claim 2, wherein the extended sequence number is a sequence number version corresponding to the number of times repeated in all sequence numbers belonging to a predetermined range, and within the predetermined range for each of the broadcast data. And the sequence number assigned by monotonically increasing by means of a concatenated value. 4. The method as claimed in claim 3, wherein the sequence number version is periodically provided from the serving cell and the target cell through a common control channel. 5. The method of claim 4, wherein the information indicating whether or not to support the selective combining for the MBMS service provided by the serving cell or the target cell through the common control channel is selected as optional combining auxiliary data along with the sequence number version. Said method characterized in that it is transmitted. The method as claimed in claim 1, wherein the selective combining is not performed if the serial number identifier received through the serving cell and the serial number identifier received through the target cell do not match. A serving cell providing an arbitrary broadcast service through a mobile terminal, a primary link established by the mobile terminal, and a cell adjacent to the serving cell providing the arbitrary broadcast service through an auxiliary link established by the mobile terminal; In a mobile communication system including at least one target cell, and a wireless network controller for providing broadcast data according to the broadcast service to the serving cell and the target cell, the mobile terminal from the serving cell and the target cell An apparatus for selectively combining broadcast data, Receives broadcast data from the serving cell and the target cell, checks whether broadcast data is repeatedly received from the serving cell and the target cell, and if the broadcast data is repeatedly received, any of the serving cell or the target cell. A duplicate check unit which selects only broadcast data received from one cell and discards broadcast data received from the other cell; And a reconfiguration buffer for reconfiguring the selected broadcast data in the order transmitted from the wireless network controller through the corresponding cells. The method of claim 7, wherein the redundancy checker compares the extended sequence numbers corresponding to each of the broadcast data from the serving cell with the extended sequence numbers corresponding to each of the broadcast data from the target cell. And determining that broadcast data having the same extended sequence number has been repeatedly received when a sequence number exists. 10. The method of claim 8, wherein the extended sequence number is a sequence number version corresponding to the number of times repeated in all sequence numbers belonging to a predetermined range, and sequentially within the predetermined range for each of the broadcast data. And the sequence number assigned by monotonically increasing by means of a concatenated value. 10. The apparatus of claim 9, wherein the sequence number version is periodically provided from the serving cell and the target cell through a common control channel. 11. The method of claim 10, wherein the information indicating whether or not to support the selective coupling for the MBMS service provided by the serving cell or the target cell through the common control channel is selected as an optional association assistance data with the sequence number version. Said device characterized in that it is transmitted. The method of claim 7, wherein the duplication checker does not perform the selective combining if the serial number assigning device identifier received through the serving cell and the serial number assigning device identifier received through the target cell do not match. The apparatus described above. A serving cell providing an arbitrary broadcast service through a mobile terminal, a primary link established by the mobile terminal, and a cell adjacent to the serving cell providing the arbitrary broadcast service through an auxiliary link established by the mobile terminal; In a mobile communication system including at least one target cell, and a wireless network controller for providing broadcast data according to the broadcast service to the serving cell and the target cell, the mobile terminal from the serving cell and the target cell A method for providing selective combining assistance data in the radio network controller to perform selective combining on broadcast data, the method comprising: Assigning sequence numbers sequentially monotonically increased within a predetermined range for each of broadcast data according to the arbitrary broadcast service, and providing them to the mobile terminal through the serving cell and the target cell; The sequence number version is initialized when the broadcast service is first started, the sequence number is assigned to the next broadcast data after the maximum sequence number in the predetermined range is given to the broadcast data. Increasing the version by 1, And periodically transmitting the sequence number version to the mobile terminal through a common control channel of the serving cell and a common control channel of the target cell. The method as claimed in claim 13, wherein the serving cell or the target cell transmits information indicating whether to support selective combining for the broadcast service through the common control channel. In the mobile communication system comprising a mobile terminal for receiving broadcast data from a plurality of cells, the mobile terminal selectively combines the broadcast data, Forming a window by an arbitrary upward end point and an arbitrary downward end point, Storing only broadcast data having a serial number not included in the window in a rearrange buffer; Changing the window by the serial number of the broadcast data stored in the rearrangement buffer, and then transmitting the broadcast data whose serial number among the broadcast data stored in the rearrangement buffer is not included in the changed window to an upper layer; Include, Here, the arbitrary upward endpoint is determined by the highest serial number of serial numbers of broadcast data received so far, and the downward endpoint is a predetermined value obtained by subtracting the size of the window from the upward endpoint. Wherein said method is determined by a result of taking a modular operation with a natural number. The method of claim 15, If the serial number of the first unreceived broadcast data among the unreceived broadcast data is not included in the window, the serial number of the next unreceived broadcast data among the unreceived broadcast data among the broadcast data stored in the rearrangement buffer And transmitting the broadcast data having a smaller serial number to the upper layer. The method of claim 15, And when the broadcast data having the serial number included in the window is received for the first time, storing the broadcast data in the rearrangement buffer. 18. The method as claimed in claim 17, wherein the broadcast data is discarded if broadcast data having a serial number included in the window is already stored in the rearrange buffer. The method of claim 17, If the serial number of the broadcast data contained in the window and stored in the rearrange buffer is the same as the serial number of the first unreceived broadcast data among the unreceived broadcast data, the first of the broadcast data stored in the rearrange buffer And transmitting the broadcast data having a serial number equal to or less than a serial number of unreceived broadcast data to the upper layer.