Multicast service providing method in mobile communication system

The present invention relates to a method of providing a Multimedia Broadcast / Multicast Service (MBMS) service of the Universal Mobile Telecommunications System (UMTS), and more particularly to a method of transmitting multicast data through a downlink shared channel.

UMTS (Universal Mobile Telecommunications System) is a third-generation mobile communication system that evolved from the European standard GSM (Global System for Mobile Communications) system, and connects GSM Core Network and WCDMA (Wideband Code Division Multiple Access). The goal is to provide improved mobile communication services based on technology.

Figure 1 shows a general UMTS network structure.

As shown in Figure 1, the UMTS system is largely composed of terminals, a UTRAN and a backbone network. A UTRAN is composed of one or more Radio Network Sub-systems (RNS), and each RNS is managed by one Radio Network Controller (RNC) and its RNC. It consists of one or more Node Bs (base stations).

Node B is managed by RNC, and is responsible for the role of UTRAN's access point (Access Point) to the terminal by receiving the information transmitted from the physical hierarchy of the terminal to the uplink and transmitting the data to the terminal to the downlink. To do. The RNC is responsible for the allocation and management of radio resources and is responsible for the role of an access point with the core network.

The main function of UTRAN is to configure and maintain a Radio Access Bearer (RAB) for calls between terminals and the backbone network. The backbone network applies end-to-end quality of service (QoS) requirements to the RAB, which supports the QoS requirements set by the backbone network. Therefore, UTRAN can meet the QoS requirements between terminations by configuring and maintaining the RAB.

The RAB service is again divided into the subordinate concept Iu Bearer service and Radio Bearer service. Here, the Iu Bearer service is responsible for the reliable transmission of user data between the UTRAN and the backbone network boundary node, and the Radio Bearer service is responsible for the reliable transmission of the user data between the terminal and the UTRAN.

Figure 2 shows the structure of the wireless protocol between the terminal and UTRAN based on the 3GPP wireless network standard.

Referring to FIG. 2, the radio protocol is composed of a physical layer, a data link layer and a network layer horizontally, and vertically, a user plane for transmitting data information and a control signal (Signaling) transmission. It is divided into a control plane for. The user plane is an area where user traffic information is transmitted such as voice and IP packets, and the control plane is an area where control information such as network interface and call maintenance and management is transmitted. Shown.

Each protocol hierarchy shown in Figure 2 is based on the lower three layers of the Open system interface (OSI) reference model, which is widely known in communication systems, and is L1 (first layer) and L2. It is divided into (2nd layer) and L3 (3rd layer).

The L1 layer (PHY) uses various wireless transmission technologies to provide information transmission services to the upper layers. The L1 layer is connected to a higher medium access control layer through a transport channel. Therefore, data moves between the MAC layer and the physical layer through the transmission channel.

The data transmitted through the transmission channel is transmitted according to the Transmission Time Interval (TTI). Physical channels carry data in fixed time units called frames. A Connection Frame Number (CF) is used between the UE and UTRAN to synchronize the transmission channels. The CFN value range is 0 to 255 for the remaining transmission channels excluding the paging channel (PCH). That is, the CFN is iteratively circulated with a period of 256 frames. In addition to CFN, System Frame Number (SFN) is used to synchronize physical channels. The SFN value range is 0 to 4095, and is repeated with a period of 4096 frames.

The Medium access control (MAC) hierarchy provides a MAC parameter reassignment service for the allocation and reallocation of radio resources, and is a higher level radio link control (Radio link control) through a logical channel. RLC) Concatenated with hierarchy. The MAC is provided with various logical channels depending on the type of information to be transmitted. Generally, when transmitting information on the control plane, the MAC uses a control channel, and when transmitting information on the user plane, it uses a traffic channel.

MAC is divided into MAC-b sublayer, MAC-d sublayer, and MAC-c / sh sublayer according to the type of transmission channel to be managed. The MAC-b sub-layer manages the BCH (Broadcast channel) of the transmission channel responsible for broadcasting system information, and the MAC-c / sh sub-layer manages the FACH (Forward access channel) and DSCH shared with other terminals. Manage shared transmission channels such as (Downlink shared channel). The MAC-c / sh sub-layer in UTRAN is located in Control RNC (CRNC) and manages the channels shared by all terminals in the cell, so there is one for each cell. And each terminal also has one MAC-c / sh sub-layer. The MAC-d sub-layer manages the DCH (Dedicated channel) of the dedicated transmission channel for a specific terminal. Therefore, the MAC-d sub-layer of UTRAN is located in the Serving RNC (SRNC) that manages the corresponding terminal, and each terminal also has one MAC-d sub-layer.

The Radio link control (RLC) hierarchy supports the transmission of reliable data, and provides the segmentation and concatenation function of the RLC service data unit (SDU) transmitted from the upper hierarchy. It can be carried out. The RLC SDU transmitted from the upper level is adjusted in size according to the processing capacity in the RLC hierarchy, and then header information is added to the MAC hierarchy in the form of protocol data unit (PDU). Is transmitted to. In the RLC hierarchy, there is an RLC buffer for storing RLC SDU or RLC PDU from the upper level.

The Broadcast / multicast control (BMC) hierarchy has the ability to schedule Cell broadcast messages (CBs) transmitted from the backbone network and broadcast CBs to each UE located in a specific cell. Do. From the aspect of UTRAN, the CB message transmitted from the upper level is transmitted to the RLC hierarchy in the form of a BMC message with information such as message ID, serial number, coding scheme, etc. added, and is transmitted to the RLC hierarchy in the form of a logical channel CTCH (Common traffic channel). ) Is transmitted to the MAC hierarchy. In this case, the logical channel (CTCH) is mapped to the FACH (Forward access channel) of the transmission channel and the S-CCPCH (Secondary common control physical channel) of the physical channel.

The Packet data convergence protocol (PDCP) hierarchy sits above the RLC hierarchy and efficiently transfers data transmitted through network protocols such as IPv4 and IPv6 over wireless interfaces with relatively low bandwidth. To transmit. For this reason, the PDCP hierarchy performs a function to reduce unnecessary control information, and this function is called header compression, which is a header compression technique defined by the Internet Engineering Task Force (IETF). RFC2507 and RFC3095 (Robust header compression: ROHC) can be used. In these methods, only necessary information is always transmitted in the header part of the data, and less control information is transmitted, so that the amount of data to be transmitted can be reduced.

The Radio Resource Control (RRC) hierarchy located at the bottom of L3 is defined only in the control plane, and the transmission channels and transmission channels and related to the setting, resetting and canceling of the radio bearer (RB) etc. Control the physical channel. At this time, the RB means a service provided by the second layer for data transmission between the terminal and the UTRAN, and in general, setting the RB is a protocol necessary for providing a specific service. It means the process of defining the characteristics of the hierarchy and channels, and setting specific parameters and operation methods for each.

Hereinafter, the MAC sub-layer will be described.

The main function of the MAC hierarchy that exists between the RLC and the physical hierarchy is the function of mapping the logical channel and the transport channel. This is because the channel processing methods of the upper layer and the lower layer of the MAC are different. That is, in the upper layer of the MAC, the control channel on the control plane and the traffic channel on the user plane are divided and processed according to the content of the data transmitted by the channel. On the other hand, in the lower hierarchy, the mapping between channels is important because the channels are divided into a shared channel (Common Channel) and a dedicated channel (Dedicated Channel) depending on whether or not the channels can be shared.

FIG. 3 is a diagram showing the mapping relationship between the logical channel on the UE side and the transmission channel. On the UTRAN side, the direction of the arrow is opposite.

Another important feature of MAC is logical channel multiplexing. MAC obtains multiplexing gain, which enhances the efficiency of transmission channels, by mapping various logical channels to one transmission channel during channel mapping. Such multiplexing is used for SRB (Signaling Radio Bearer) or Packet Service (PS) RAB, especially because it can provide high gain for signal ring information and packet data in which data is transmitted intermittently. To. In the case of line (Circuit Service: CS) RAB, the multiplexing function is generally not used because the data is transmitted continuously.

Therefore, the MAC provides the flexibility of channel selection and the efficiency of channel resources through channel mapping and logical channel multiplexing. However, additional features are needed to support channel mapping and logical channel multiplexing. Therefore, MAC additionally performs the following four functions.

1. Priority Handling The MAC performs a Priority Handling function to support various channel mapping structures. The priority processing includes priority processing between two types of various UEs and priority processing for one UE.

Priority processing between UEs corresponds to the case where data of various UEs is transmitted through a shared transmission channel (FACH or DSCH) on the downlink (Downlink). In this case, the MAC transmits the data of the UE with the highest priority first. That is, the MAC can improve the efficiency of channel resources by appropriately allocating shared channels for each transmission time interval (TTI) for each UE. This is related to the Dynamic Scheduling feature.

The priority processing for one UE corresponds to the case where various logical channels belonging to one UE are mapped to one transmission channel. The MAC determines the priority according to the Logical Channel Priority. This is related to Transport Format Combination selection, but the MAC selects the transmission format combination that can transmit the data of the high-priority logical channel first.

2. Transport Format Combination selection The MAC transmits each transport block (TB) to the physical hierarchy through the transmission channels. Transport Format (TF) means a regulation on the size and number of TBs transmitted by one transmission channel. When determining the TF for a particular transmission channel in this way, the MAC should even consider Transport Channel Multiplexing in the physical hierarchy.

Transmission channel multiplexing is the mapping of multiple transmission channels to a single coded composite transport channel (CCTrCH). Although the function is performed in the physical hierarchy, when determining the TF, the MAC should consider all transmission channels mapped to the same CCTrCH. Actually, the amount of data processed in the physical layer is the amount transmitted through CCTrCH, so the MAC determines the TF of each transmission channel in consideration of CCTrCH. At this time, the combination of each TF is combined with the transmission format. It is called (Transport Format Combination: TFC). Such TFCs are not determined by the MAC itself, but the MACs are selected from a set of available TFCs (TFC Set: TFCS) known by the RRC hierarchy. That is, the RRC informs the MAC of the TFCS that can be used for one CCTrCH at the time of initial setting, and the MAC selects an appropriate TFC in the TFCS for each TTI.

It is a function of MAC to select an appropriate TFC for each TTI within a given TFCS, which consists of two stages.

First, the MAC constructs a valid TFC set within the TFCS assigned to CCTrCH and selects the appropriate TFC within the configured valid TFC set. The valid TFC set is the set of each TFC that can actually be used for the corresponding TTI from the assigned TFCS, and this is to consider the channel environment that changes every moment. When selecting the TFC to be used for the TTI in such a valid TFC set, the MAC selects the TFC based on the priority of the logical channel. That is, the MAC selects a TFC that can preferentially transmit data of a logical channel having a high priority, and such selection of a TFC is also related to the priority processing function.

And since one transmission channel constitutes one CCTrCH for the shared transmission channels of Uplink such as RACH and CPCH, the term TF selection is used instead of TFC for those channels. To.

3. Identification In addition, MAC requires an identification function. The reason is that, firstly, since the shared transmission channel is shared and used by various UEs, it is necessary to identify the UE, and secondly, it is necessary to identify each logical channel by logical channel multiplexing. Is. Therefore, the MAC inserts four types of fields in the header of the MAC PDU for identification, as shown in Figure 4. Each field of the MAC header does not always exist, and whether or not it exists is determined by the mapping relationship between the logical channel and the transmission channel.

Terminal identification is required when dedicated logical channels such as DCCH and DTCH are mapped to shared transmission channels such as RACH, FACH, CPCH (Control Physical Channel), DSCH and USCH (Uplink Shared Channel). To identify the terminal, the MAC additionally transmits the Radio Network Temporary Identity (RNTI), which is the identification information of the terminal, to the UE-ID field of the header. At this time, since the types of RNTI include U-RNTI (UTRAN RNTI), C-RNTI (Cell RNTI) and DSCH-RNTI, the MAC also has a UE-ID type field indicating what kind of RNTI was used. It is additionally transmitted.

Identification between dedicated logical channels is done through the C / T field. The reason is that, firstly, unlike other logical channels, multiple dedicated logical channels are mapped to one transmission channel, and secondly, the dedicated logical channel is MAC-d in the Serving Radio Network Controller (SRNC). This is because the other logical channels are processed by MAC-c / sh in the Control Radio Network Controller (CRNC). Each dedicated logical channel mapped to one transmission channel has its own Logical channel identity, which is used as the C / T field value. If there is only one dedicated logical channel in the transmission channel, the C / T field will not be used.

Figure 5 shows the MAC header information based on the mapping relationship between the conventional dedicated logical channel and the transmission channel.

As shown in Figure 5, the C / T field exists only when multiple dedicated logical channels (DCCH or DTCH) are mapped, the N display means that there is no header at all, and-the display is mapping related. Means that there is no. Also, since the UE-ID field always exists together with the UE-ID type field, it is simply written as UE-ID.

4. Traffic Volume Measures and Transport Channel Type Switching To help the RRC dynamically control the radio bearer, the MAC has a volume measurement and transmission channel type. Perform functions such as change.

Traffic measurement is performed on the transmission channel. The MAC measures the RLC buffer amount of all the logical channels mapped to the transmission channel for each TTI, and then calculates the transport channel traffic volume by combining them. In this case, the traffic volume of the transmission channel indicates the amount of data that the transmission channel should transmit in the future.

The MAC reports the measurement results to the RRC, but the measurement results are reported when certain conditions are met, unlike the traffic volume measurement performed for each TTI. There are two types of reporting: an event trigger method that reports when the measurement result deviates from the critical value, and a periodic method that reports at predetermined time intervals.

Upon receiving the report of the measurement result, the RRC determines whether the current transmission channel is suitable for each wireless bearer, and if not, instructs the MAC to change the transmission channel of the wireless bearer. After all, the transmission channel type change can be said to be a function for efficiently managing the resources of the transmission channel by selecting and using an appropriate transmission channel according to the given amount of data.

Hereinafter, the description will be given to the Multimedia Broadcast / Multicast Service (MBMS).

MBMS is a service that uses a unidirectional point-to-multipoint bearer service to transmit multimedia data such as audio, video, and video to multiple terminals. MBMS is divided into broadcast mode and multicast mode. That is, the MBMS service is divided into an MBMS broadcasting service and an MBMS multicast service.

MBMS broadcast mode is a service that transmits multimedia data to all users in the broadcast area. At this time, the broadcasting area refers to an area where broadcasting services are possible. There are one or more broadcasting areas in one PLMN, one or more broadcasting services are provided in one broadcasting area, and one broadcasting service is provided to a plurality of broadcasting areas.

MBMS multicast mode is a service that transmits multimedia data only to specific user groups in the Multicast area. At this time, the multicast area refers to an area where the multicast service is possible. There are one or more multicast areas in one PLMN, and one or more multicast services are provided in one multicast area. In addition, one multicast service is provided to a plurality of multicast regions.

Users are required to join a Multicast group in order to receive a particular multicast service in MBMS multicast mode. At this time, the multicast group refers to a group of users who receive a specific multicast service, and participation refers to the act of joining a multicast group gathered to receive a specific multicast service.

MBMS data is transmitted from the RNC to the terminal via the base station using the services of the PDCP layer, RLC layer, MAC layer and physical layer located on the user plane of the UTRAN protocol. That is, the MBMS data transmitted from the core network (CN) is transmitted to the RLC UM individual through the RLC UM SAP after header compression is performed in the PDCP hierarchy, and the RLC UM individual is again a common traffic channel which is a logical channel. It is transmitted to the MAC hierarchy through. After attaching a MAC header to the transmitted MBMS data, the MAC layer is transmitted to the physical layer of the base station through the common transmission channel, and the transmitted MBMS data is common after undergoing processes such as coding and modulation in the physical layer. It is transmitted to the terminal through the physical channel.

MBMS RB of radio bearer (RB) for MBMS is responsible for transmitting user data of one specific MBMS service transmitted from the core network to UTRAN to a specific terminal group. MBMS RB is roughly divided into point-to-multipoint and point-to-point. UTRAN selects and uses one of the above two types of MBMS RBs to provide MBMS services. To select an MBMS RB, UTRAN first knows the number of users of a particular MBMS service in a cell. UTRAN sets a threshold internally, but if the number of users in the cell is less than the threshold, set a point-to-point MBMS RB and if the number of users in the cell is greater than the threshold Sets a point-to-many MBMS RB.

The Third generation partnership project (3GPP) wireless system proposes a High Speed Downlink shared channel (HS-DSCH), especially to support packet data services.

In order for DSCH to provide multicast services, it should support point-to-multi radio bearers, where common logical channels such as CTCH or MTCH (MBMS traffic channel) should be mapped to DSCH. .. However, since the conventional DSCH only transmitted the data of the dedicated logical channel, the MAC header did not include a field for identifying the logical channel mapped to the DSCH. Therefore, when transmitting common logical channel data through DSCH, if the MAC header does not include a field indicating the logical channel type, the terminal cannot know the type of logical channel to which the data received through DSCH belongs. That is, it does not know what kind of logical channel the received data should be transmitted to, but this increases the probability that a communication error will occur.

The above references are incorporated herein by reference as appropriate for the appropriate teaching of additional or alternative details, features and / or technical background.

<p> An object of the present invention is to provide a data transmission method capable of distinguishing the types of service data when transmitting multicast service data through a shared channel.</p><p> Another object of the present invention is to provide a data transmission method capable of providing a multicast service through a shared channel.</p>

<p> In order to achieve such an object, in a wireless system in which service data of a logical channel is mapped to a common transmission channel and transmitted to a terminal, the multicast service method according to the present invention assigns a logical channel identifier to the transmitted service data. It includes a stage of adding and a stage of mapping the corresponding service data to a common transmission channel.</p><p> Preferably, the logical channel is a common logical channel or a dedicated logical channel, and the common logical channel is a common traffic channel (CTCH), a common control channel, an MBMS traffic channel (MTCH) or an MBMS control. It is a channel (MBMS Control channel: MCCH).</p><p> Preferably, the common transmission channel is a Downlink Shared Channel (DSCH).</p><p> Preferably, the common transmission channel is a high speed downlink shared channel (HS-DSCH).</p><p> Preferably, the service data is Multimedia Broadcast / Multicast Service (MBMS) data.</p><p> Preferably, the service data is an MBMS protocol data unit and the MBMS protocol data unit is a MAC protocol data unit.</p><p> Preferably, the logical channel identifier is a Target Channel Type Field (TCTF), which indicates whether the logical channel mapped to the common transmission channel is a common logical channel or a dedicated logical channel. The logical channel identifier is added when service data is transmitted from the Medium Access Control (MAC) hierarchy to the lower hierarchy.</p><p> Preferably, the logical channel identifier is added by a common type MAC entity such as the MAC-c / sh hierarchy that manages the common radio resources of all terminals in the cell. To do.</p><p> Preferably, the logical channel identifier is included in the header of the service data, which header is the MAC header.</p><p> The multicast service method according to the present invention further includes a step of adding a terminal identifier and an indicator indicating the type of the terminal identifier to the transmitted service data. The terminal identifier is characterized by being an MBMS radio network temporary identifier (RNTI), a terminal group identifier, or an MBMS service identifier.</p><p> To achieve this purpose, a wireless communication system that maps service data of a common logical channel or a dedicated logical channel to a downlink shared channel (DSCH) or a high-speed downlink shared channel (HS-DSCH) and transmits it to a terminal. In the multicast service method according to the present invention, when the service data is transmitted from the Medium Access Control (MAC) layer through the DSCH or HS-DSCH, an indicator indicating a logical channel mapping type is also transmitted to the corresponding service data. ..</p><p> Preferably, the service data is Multimedia Broadcast / Multicast Service (MBMS) data.</p><p> Preferably, the service data is an MBMS protocol data unit, and the MBMS protocol data unit is a MAC protocol data unit.</p><p> Preferably, the indicator is a Target Channel Type Field (TCTF).</p><p> Preferably, the MAC hierarchy is a MAC-c / sh hierarchy that manages common resources of all terminals in the cell.</p><p> Preferably, the directive is included in a header of service data, which header is a MAC header. The MAC header further includes a terminal identifier and an indicator indicating the type of terminal identifier.</p><p> Preferably, the terminal identifier is an MBMS wireless network temporary identifier (MBMS RNTI), a terminal group identifier or an MBMS service identifier.</p><p> In order to achieve such an object, in a wireless communication system that transmits service data received through a downlink shared channel to a higher layer of a terminal, the multicast service method according to the present invention reads a logical channel identifier from the service data. This includes a step of recognizing the logical channel to which the corresponding data is transmitted and a step of transmitting the received data to the upper layer of the terminal through the recognized logical channel.</p><p> Preferably, the received data is Multimedia Broadcast / Multicast Service (MBMS) data.</p><p> Preferably, the logical channel identifier is a Target Channel Type Field (TCTF).</p><p> Preferably, when the transmitted logical channel is a common logical channel, the received data is transmitted to the Resource Link Control (RLC) hierarchy through the common logical channel. Further, when the logical channel to be transmitted is a dedicated logical channel, the received data is transmitted to the MAC-d layer that manages the dedicated resource through the dedicated logical channel.</p><p> Preferably, the recognition step is performed in a common type medium access control (MAC) hierarchy of terminals, such as the MAC-c / sh hierarchy.</p><p> In order to achieve such an object, in a wireless communication system that transmits data received through a downlink shared channel to a higher layer of a terminal, the multicast service method according to the present invention is a logical channel identifier and a terminal from the received data. It includes a step of reading an identifier and a step of transmitting the received data to a higher layer through a predetermined logical channel based on the read logical channel identifier and terminal identifier.</p><p> Preferably, the logical channel identifier is a Target Channel Type Field (TCTF).</p><p> Preferably, the terminal identifier is an MBMS wireless network temporary identifier (MBMS RNTI), a terminal group identifier or an MBMS service identifier.</p><p> Preferably, the transmission step is a step of checking whether the logical channel identifier indicates a common logical channel, a step of checking whether the terminal identifier indicates a terminal group to which the corresponding terminal belongs, and a step of checking whether the reception is performed according to the check result. It consists of a stage of transmitting data to a higher layer.</p><p> Preferably, when the logical channel identifier points to a common logical channel and the terminal identifier points to a terminal group to which the terminal belongs, the received data is transmitted to the Resource Link Control (RLC) hierarchy through the common logical channel. On the other hand, the logical channel identifier indicates the common logical channel, but if the terminal identifier does not indicate the terminal group to which the terminal belongs, the received data is discarded.</p><p> Preferably, when the logical channel identifier indicates a dedicated logical channel and the terminal identifier indicates a terminal group to which the terminal belongs, the received data is transmitted to the MAC-d hierarchy. On the other hand, the logical channel identifier indicates the dedicated logical channel, but if the terminal identifier does not indicate the terminal group to which the terminal belongs, the received data is discarded.</p><p> Further advantages, objectives and features of the present invention will be in part set forth in the description below, and in part may be apparent to one of ordinary skill in the art during the following tests or confirmed from the practice of the present invention. The objects and advantages of the present invention may be recognized and achieved as specifically set forth in the appended claims.</p>

The present invention is embodied in a mobile communication system such as UMTS (universal mobile telecommunications system) developed by 3GPP. However, the present invention also applies to communication systems operated by other standards.

The present invention provides a method for determining to what logical channel the terminal should transmit the data received through the DSCH when the UTRAN transmits point-to-multi-radio bearer data to the terminal through the downlink shared channel (DSCH). Present. The DSCH of the present invention provides not only a point-to-point wireless bearer service but also a point-to-point wireless bearer service, and particularly transmits data of a common traffic channel such as CTCH and MTCH to a specific terminal group.

In the present invention, the DSCH used to provide the point-to-multi-radio bearer service to distinguish it from the conventional DSCH is called the point-to-many DSCH and is used to provide the point-to-point wireless bearer service. DSCH is called point-to-point DSCH. Also in the present invention, the DSCH includes a high speed downlink shared channel (HS-DSCH) so that the DSCH is replaced by HS-DSCH.

The present invention transmits multicast service data transmitted through a downlink shared channel (DSCH) including an indicator indicating whether the data is multicast data or dedicated data. The directive is included in the header of the MAC PDU as a Target Channel Type Field (TCTF).

Hereinafter, embodiments of the present invention will be described in detail.

Since the conventional shared transmission channel (DSCH) only transmitted the data of the dedicated logical channel, the MAC header did not include a field for identifying the type of logical channel mapped to DSCH. However, in order to provide multicast service as well as dedicated service, DSCH should support point-to-multi-radio bearer (RB), and in order for the DSCH to support point-to-multi-radio bearer (RB), Common logical channels such as CTCH or MTCH should be mapped to DSCH.

FIG. 6 shows the structure of MAC PDU for point-to-many DSCH according to the present invention.

As shown in Figure 6, the MAC PDU transmitted through DSCH consists of a MAC header and a MAC SDU. The MAC header contains information such as TCTF, UE ID Type and MBMS identifier (m-RNTI).

The MAC header contains a TCTF field to identify the type of logical channel. The TCTF field indicates whether the channel mapped to DSCH is a dedicated logical channel (DTCH / DCCH) or a common logical channel (CTCH, BCCH, CCCH, MTCH, MCCH). That is, it indicates whether the multicast service data transmitted through the downlink shared channel (DSCH) is multicast data or dedicated data.

The UE ID Type field indicates whether the type of UE ID contained in the MAC header is U-RNTI, C-RNTI, DSCH-RNTI, or MBMS identifier (m-RNTI). ..

The MBMS identifier (m-RNTI) field indicates terminal identifier information. Generally, for point-to-point DSCH, DSCH-RNTI is used as the UE ID in the MAC header, but for point-to-many DSCH, UE ID. The MBMS identifier (m-RNTI) is used as. Further, instead of the MBMS identifier, the MBMS service identifier or the terminal group identifier is used as the UE ID.

Therefore, the UTRAN MAC attaches MAC header information to the RLC PDU transmitted through the MTCH to form a MAC PDU, that is, a transmission block, and then transmits the RLC PDU to the physical hierarchy through the DSCH.

Figure 7 shows the structure of CRNC common type MAC for point-to-many DSCH. The common type MAC of the CRNC supports MBMS with UTRAN, and MAC-c / sh is used as the common type MAC of the CRNC.

As shown in FIG. 7, there is one RLC UM individual (Unacknowledged Mode Entity) 11 of RLC 10 for each MBMS point-to-multi-radio bearer. Different RLC UM individuals transmit MBMS data with different quality of service (QoS). One RLC UM individual has one MTCH. Also, MTCH is used instead of CTCH in Figure 7.

After receiving the RLC PDU through CTCH, MAC-c / sh20 adds m-RNTI and UE ID to the RLC PDU and then performs TCTF multiplexing (S21, S23, S24). At this time, step S22 means flow control between MAC-c / sh and MAC-d.

After that, MAC-c / sh has a downlink scheduling function that appropriately allocates downlink shared channels to terminals for each transmission time interval (TTI) and a priority handling function that transmits high-priority data first. (S25). At this time, MAC-c / sh20 can perform the following three types of priority processing.

1. Priority processing between MBMS multicast groups (or MBMS services) 2. Priority processing for one MBMS multicast group (or one MBMS service) 3. Data-to-data priority processing within MBMS multicast groups (or MBMS services) For example, if the data for a diverse MBMS multicast group is transmitted on a downlink through a common transmission channel such as FACH, DSCH or HS-DSCH, the MAC-c / sh20 will have the highest priority MBMS data first. To transmit. This is related to the Dynamic Scheduling feature, which can increase the efficiency of channel resources by appropriately allocating common channels to terminals at each transmission time interval (TTI).

Then, when various logical channels belonging to one MBMS service or one MBMS multicast group are mapped to one transmission channel, MAC-c / sh20 prioritizes by logical channel priority (Logical Channel Priority). decide. This is related to Transport Format Combination selection, where MAC-c / sh selects the Transport Format Combination (TFC) that transmits the data of the high-priority logical channel first. (S26).

MAC-c / sh is a downlink code in which the corresponding MAC PDU is transmitted for each TTI after selecting the TFC of each data to be transmitted to the point-to-many DSCH channel, that is, PDSCH (Physical Downlink shared channel) (PDSCH). Select the channel code for (Physical Channel) (S27). The PDSCH channel code on a particular PDSCH radio frame is used to carry the MBMS service or MBMS multicast group data in question.

Figure 8 shows the structure of the terminal common MAC for point-to-many DSCH. The common type MAC of the terminal supports MBMS in the UE, and MAC-c / sh is used as the common type MAC in the terminal.

As shown in FIG. 8, the physical hierarchy of terminals belonging to the MBMS multicast group first receives DSCH control information through DPCH, and then receives DSCH during a specific radio frame according to the contents of the received DSCH control information. Decide if you want to. If the DSCH control information signals that DSCH is received during a specific radio frame for the MBMS service, the physical hierarchy of the terminal will send a MAC PDU after receiving the DSCH during the specific radio frame by the DSCH control information. Decode and transmit to MAC-c / sh of the terminal through the transmission channel.

The terminal MAC-c / sh40 demultiplexes the TCTF field from the received MAC PDU (S43), and the information in the TCTF field inserted in the MAC PDU shows a dedicated logical channel (DTCH or DCCH) mapping, or is common. Check if it shows a logical channel (eg, CTCH, MTCH or MCCH) mapping.

As a result of the check, when the information in the TCTF field shows the mapping of the dedicated logical channel (DTCH or DCCH), MAC-c / sh40 processes the data in the same way as the conventional point-to-point DSCH. That is, when the information in the TCTF field indicates the dedicated logical channel mapping, the terminal MAC-c / sh reads the UE ID from the MAC header and determines whether the corresponding UE ID is its own ID. As a result of the determination, if the corresponding UE ID is itself, the terminal MAC-c / sh transmits the corresponding MAC PDU to the MAC-d hierarchy.

However, if the information in the TCTF field inserted in the MAC PDU indicates a common logical channel (eg, CTCH or MTCH) mapping, the terminal MAC-c / sh contains the UE ID Type field with MBMS RNTI (m-RNTI). Check if you want to instruct. If the UE ID Type field does not indicate inclusion of m-RNTI, MAC-c / sh discards the corresponding MAC PDU.

On the other hand, if the UE ID Type field indicates the inclusion of m-RNTI, MAC-c / sh40 reads m-RNTI from the MBMS identifier field (S43), and the read m-RNTI tries to receive the terminal. Check if you want to direct the multicast service. As a result of the check, if the read m-RNTI does not indicate the multicast service that the terminal is trying to receive, the corresponding MAC PDU is discarded.

On the other hand, when instructing the multicast service that the relevant m-RNTI is trying to receive, the MAC-c / sh40 uses the type of logical channel (eg, CTCH) and identification information inserted in the relevant MAC PDU. Then, the RLC PDU is transmitted to the RLC UM individual 31 of the terminal RLC layer 30 through the corresponding common logical channel (CTCH). That is, in the terminal MAC-c / sh40, data (MAC PDU) is transmitted from any kind of logical channel based on the information in the TCTF and MBMS identifier fields inserted in the MAC PDU, and the terminal RLC hierarchy is transmitted through any logical channel. You will know if it will be transmitted.

As described above, the present invention can include the TCTF field in the header of the MAC PDU transmitted by DSCH to understand the type of logical channel to be mapped when DSCH assists the point-to-multi-radio bearer. it can. As a result, the terminal MAC-c / sh that receives the DSCH data has an effect that it can easily grasp what kind of logical channel the data is transmitted from and what kind of logical channel the data is transmitted to the terminal RLC hierarchy.

The present invention has been described based on the embodiments shown in the drawings, but this is merely an example, and a person having ordinary knowledge in the present technical field can obtain various modifications. And it should be understood that other equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention should be defined by the technical idea of the attached claims.

The present invention will be described in detail with reference to the following drawings. In these drawings, the same reference numbers refer to the same elements.<figref num="1">Figure 1 shows the network structure of a general UMTS system.</figref><figref num="2">Figure 2 shows the structure of the Radio Access Interface protocol between a single terminal and UTRAN, based on the 3GPP Radio Access Network Standard.</figref><figref num="3">FIG. 3 is a diagram showing an example of the mapping relationship between the logical channel and the transmission channel on the UE side.</figref><figref num="4">Figure 4 shows the MAC PDU structure for traditional point-to-point DSCH.</figref><figref num="5">FIG. 5 is a diagram showing MAC header information based on the mapping relationship between the conventional dedicated logical channel and the transmission channel.</figref><figref num="6">FIG. 6 is a diagram showing the structure of MAC PDU for point-to-many DSCH according to the present invention.</figref><figref num="7">FIG. 7 is a diagram showing the common type MAC structure of CRNC and the multicast data processing method for point-to-many DSCH.</figref><figref num="8">FIG. 8 is a diagram showing a common type MAC structure of terminals and a multicast data processing method for point-to-many DSCH.</figref>

Code description

MBMS: Multimedia Broadcast / Multicast Service TCTF: Target Channel Type FieldRRC: Radio Resource Control