Patent Publication Number: US-10334560-B2

Title: Method and apparatus for user equipment receiving MBMS service processing semi-permanent scheduling from MBSFN subframe in wireless communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. application Ser. No. 14/115,198, which was the National Stage of International application PCT/KR2012/003492 filed on May 3, 2012, which claimed the benefit under 35 U.S.C. § 119(e) of a U.S. Provisional application filed on May 3, 2011 in the U.S. Patent and Trademark Office and assigned Ser. No. 61/481,878, and of a U.S. Provisional application filed on May 10, 2011 in the U.S. Patent and Trademark Office and assigned Ser. No. 61/484,645, the entire disclosure of each of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a wireless communication system and, in particular, to a semi-persistent scheduling-processing method and apparatus of a user equipment receiving MBMS in MBSFN subframe. 
     BACKGROUND ART 
     The mobile communication system has been developed for the user to communicate on the move. With the rapid advance of technologies, the mobile communication system has evolved to the level capable of providing high speed data communication service as well as voice telephony service. 
     Recently, as one of the next generation mobile communication system, Long Term Evolution (LTE) is on the standardization by the 3rd Generation Partnership Project (3GPP). LTE is a technology designed to provide high speed packet-based communication of up to 100 Mbps and aims at commercial deployment around 2010 timeframe. In order to accomplish the aim, a discussion is being held on several schemes: one scheme for reducing the number of nodes located in a communication path by simplifying a configuration of the network, and another scheme for maximally approximating wireless protocols to wireless channels. 
     Meanwhile, unlike voice service, the data service is provided on the resource determined according to the data amount to be transmitted and channel condition. Accordingly, the wireless communication system, especially cellular communication, is provided with a scheduler manages transmission resource allocation in consideration of the required resource amount, channel condition, data amount, etc. This is the fact in the LTE system as the next generation mobile communication system, and the scheduler located at the base station (eNB) manages the transmission resource allocation. 
     Recent studies are focused on the LTE-Advanced (LTE-A) for improving data rate with the adaptation of several new techniques to legacy LTE system. Multimedia Broadcast/Multicast Service one of the techniques to enhanced along with the LTE-A system. MBMS is a broadcast service provided in the LTE system. 
     Meanwhile, it increases signaling overhead to provide scheduling information on every transmission of data burst for the traffic requiring periodic radio resource allocation such as VoIP. Accordingly, a scheduling technique for providing the user equipment (UE), in advance, with the scheduling information allocating radio resource periodically in order for the UE to transmit data on the radio resource allocated periodically is referred to as Semi-Persistent Scheduling (SPS). 
     However, there is no clear rule specified how to processing the situation when the downlink subframe having the downlink resource allocated through SPS and the resource for providing MBMS. There is therefore a need of defining operations of the UE clearly. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     The present invention has been conceived to solve the above problem and aims to provide a SPS processing method and apparatus that is capable of allowing the UE receiving MBMS to process SPS in MBSFN subframe. 
     Solution to Problem 
     In accordance with an aspect of the present invention, a downlink-scheduling processing method of a terminal receiving Multimedia Broadcast/Multicast Service (MBMS) in a mobile communication system includes detecting occurrence of downlink scheduling at a certain Transmission Time Interval (TTI), determining whether to process the downlink scheduling depending on whether the terminal is configured transmission mode 9 or the TTI matches Multimedia Broadcast/Multicast Service Frequency Network (MBSFN) subframe, and processing or ignoring the downlink scheduling according to determination result. 
     In accordance with another aspect of the present invention, a terminal for receiving Multimedia Broadcast Multicast Service (MBMS) and processing downlink scheduling in a mobile communication system includes a transceiver which transmits and receives signals to and from a base station and a controller which detects occurrence of downlink scheduling at a certain Transmission Time Interval (TTI), determines whether to process the downlink scheduling depending on whether the terminal is configured transmission mode 9 or the TTI matches Multimedia Broadcast/Multicast Service Frequency Network (MBSFN) subframe, and controls to process or ignore the downlink scheduling according to determination result. 
     Advantageous Effects of Invention 
     According to the present invention, the UE receiving MBMS operates in one of unicast processing mode and MBMS processing mode selectively depending on whether a certain transmission time interval (TTI) is of MBSFN or the UE is in operating in transmission mode 9. Accordingly, when the subframe in which downlink resource is allocated through SPS matches the subframe designated for MBMS, it is possible to define the operation of the UE for processing the subframe as the subframe of the downlink resource allocated through SPS or as the subframe for MBMS. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating a concept of MBMS. 
         FIG. 2  is a diagram illustrating downlink channel mapping relationship for used in MBSFN transmission. 
         FIG. 3  is a diagram illustrating a structure of the downlink frame for use in the LTE system. 
         FIG. 4  is a signal flow diagram illustrating a MBSFN reception procedure of the UE. 
         FIG. 5  is a signal flow diagram illustrating a procedure of activating and deactivating SPS. 
         FIG. 6  is a diagram illustrating SPS operation and retransmission method in downlink. 
         FIG. 7  is a flowchart illustrating an operation procedure of the UE according to an embodiment of the present invention. 
         FIG. 8  is a diagram for explaining an MBMS counting request/response procedure in detail. 
         FIG. 9  is a block diagram illustrating a configuration of the UE according to an embodiment of the present invention. 
         FIG. 10  is a block diagram illustrating a configuration of the eNB according to an embodiment of the present invention. 
     
    
    
     MODE FOR THE INVENTION 
     The present invention relates to a Semi-Persistent Scheduling (SMS) processing method and apparatus of a UE that is capable of processing SMS in MBSFN subframe. 
     Exemplary embodiments of the present invention are described with reference to the accompanying drawings in detail. The same reference numbers are used throughout the drawings to refer to the same or like parts. Detailed description of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present invention. 
       FIG. 1  is a diagram illustrating a concept of MBMS. 
     The MBMS service area  100  is a network area formed with a plurality of eNBs capable of Multimedia Broadcast/Multicast Service Single Frequency Network (MBSFN) transmission. 
     The MBSFN area  105  is the network area composed of several cells integrated for MBSFN transmission, and the cells of the MBSFN network are synchronized each other for MBSFN transmission. 
     All of the cells with the exception of MBSFN Area Reserved Cells  110  are used for MBSFN transmission. The MBSFN Area Reserve cell  110  are not used for MBSFN transmission but for other purpose on the radio resource allocated for MBSFN transmission with restricted transmit power. 
       FIG. 2  is a diagram illustrating downlink channel mapping relationship for used in MBSFN transmission. 
     As shown in  FIG. 2 , MCH  200  is used between the MAC layer and the physical layer, and the MCH  200  is mapped to PMCH  205  of the physical layer. 
     Typically, the unicast scheme for transmitting data to a specific UE uses Physical Downlink Shared Channel (PDSCH)  210 . 
       FIG. 3  is a diagram illustrating a structure of the downlink frame for use in the LTE system. 
     As shown in  FIG. 3 , a radio frame  300  consists of 10 subframes  305 . Here, each subframe is classified into one of normal subframe  310  for use in normal data transmission and Multimedia Broadcast/Multicast Service Single Frequency Network (MBSFN) subframe  315 . 
     The normal subframe and the MBSFN subframe are different from each other in number of Orthogonal Frequency Division Multiplexing (OFDM) symbols, length of cyclic prefix, and structure and number of Cell-specific Reference Signal (CRS). 
     Meanwhile, the MBSFN subframe is used for broadcasting/multi casting data in Rel-8 and Rel-9 systems. However, with the system advance, the MBSFN subframe can be used for unicast as well as broadcast/multicast in LTE Rel-10 or later. 
     In LTE, each UE is configured in a Transmission Mode (TM) associated with Multi-antenna technique and Reference Signal (RS) in order to use Physical Downlink Shared Channel (PDSCH) efficiently. 
     In LTE Rel-10, there are transmission modes of TM1 to TM9. Each UE is configured in one of the TMs for PDSCH transmission, TM8 introduced in Rel-9 and TM9 in Rel-10. 
     Particularly, TM9 supports Single User Multi-Input Multi-Output (SU-MIMO) having up to 8 ranks. TM9 supports multi-layer transmission up to 8 layers using Rel-10 Demodulation Reference Signal (DMRS) in demodulation. Although the Rel-10 DMRS is precoded, it is not necessary to notify the receiver of the corresponding precoder index. In order to support TM9, Downlink Control Information (DCI) format 2C is newly defined in Rel-10. It is noted that the terminals of releases prior to Rel-10 do not attempt decoding in MBSFN subframe. Accordingly, if it is required for all UEs to attempt decoding in MBSFN subframe, this means that the old release UEs has to be upgraded. 
     In the present invention, the MBSFN subframe-carrier unicast data reception capability is applied to the UEs requiring it, e.g. the UEs requiring high speed data communication, other than all UEs. 
     Among the aforementioned TMs, TM9 is the transmission mode of maximizing the transmission efficiency using multiple antennas. In the present invention, if it is required to increase the data throughput of a UE through unicast data reception in MBSFN subframe, the eNB configures the UE to operate in TM9 such that the UE operating in TM9 receives unicast data in MBSFN subframe. 
     For unicast data transmission, it is necessary to notify of the resource for transmitting data using PDCCH and the data are transmitted through PDSCH in the LTE system. The UE has to determine whether the PDCCH has the information on the resource allocated to the UE before receiving the actual data. 
     In the meantime, the resource allocation information for MBSFN is acquired through more complex procedure. The eNB notifies the UE of the transmission position of Multicast Control Channel (MCCH) per MBSFN Area through System Information Block 13 (SIB13) broadcast. The MCCH includes resource allocation information for MBSFN such that the UE decodes the MCCH to check the transmission position of MBSFN subframe. 
     As described above, the reason for providing the MBMS resource allocation information through a method different from the conventional unicast is because the MBMS has to be provided to even the UE in the idle mode. Accordingly, the transmission position of MCCH as control channel is notified using the SIB13 broadcast. 
       FIG. 4  is a signal flow diagram illustrating a MBSFN reception procedure of the UE. 
     The UE  400  receives SIB2 broadcast by the eNB at step  410 . The MBSFN-SubframeConfigList IE indicates the subframes capable of being used for MBSFN transmission. The MBSFN-SubframeConfigList IE includes MBSFN-SubframeConfig IE and indicates radio frame including MBSFN subframes and the subframes that can be used as MBSFN subframes in the radio frame. Table 1 shows an exemplary MBSFN-SubframeConfig IE. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 -- ASN1START 
                   
               
               
                 MBSFN-SubframeConfig ::= 
                 SEQUENCE { 
               
               
                 radioframeAllocationPeriod 
                   ENUMERATED {n1, n2, 
               
               
                 n4, n8, n16, n32}, 
               
               
                   radioframeAllocationOffset 
                   INTEGER (0..7), 
               
               
                   subframeAllocation 
                     CHOICE { 
               
               
                     oneFrame 
                       BIT STRING 
               
               
                 (SIZE(6)), 
               
               
                     fourFrames 
                       BIT STRING 
               
               
                 (SIZE(24)) 
               
               
                   } 
               
               
                 } 
               
               
                 -- ASN1STOP 
               
               
                   
               
            
           
         
       
     
     Here, the radio frame allocation period (radioFrameAllocationPeriod) and radio frame allocation offset (radioFrameAllocationOffset) are used for indicating the radio frame having MBSFN subframe, and the radio frame fulfilling equation “SFN mod radioFrameAllocationPeriod=radioFrameAllocationOffset” includes MBSFN subframes. 
     SFN is System Frame Number indicating the number of the radio frame. This repeats in the range from 0 to 1023. The subframe allocation (subframeAllocation) indicates the MBSFN subframes in the radio frame indicated by the equation. The indication may be done by one or four radio frames. In the case of using the unit of one radio frame, oneFrame IE indicates the subframe. Among the ten subframes of one radio frame, the 1 st , 2 nd , 3 rd , 6 th , 7 th , 8 th  subframes may be configured as MBSFN subframes. Accordingly, the oneFrame IE indicates the MBSFN subframe among the enumerated subframes using 6 bits. In the case of using the unit of four radio frames, the fourFrames IE indicates the MBSFN subframes. In order to cover four radio frames, total 24 bits are used to indicate MBSFN subframes among the enumerated subframes of every radio frame. Accordingly, the UE is capable of checking the subframe that may be configured as MBSFN subframes precisely. 
     If the terminal  400  wants to receive MBSFN data, it receives SIB13 broadcast by the eNB  405  at step  415 . The MBSFN-AreaList IE of the SIB13 including position information on MCCH transmission per MBSFN area of the cell such that the UE receives MCCH based on this information at step  420 . 
     The MBSFNAreaConfiguration IE of the MCCH indicates the position of the resource used for MBSFN transmission, and the UE receives MBSFN subframe using this information at step  425 . The UE acquires the position of the MBSFN subframe carrying the wanted MTCH in the MCH scheduling information MAC CE as one of MAC Control Elements (CEs) of the received MAC PDU at step  430 . The UE decodes the intended MTCH using the MCH scheduling information at step  435 . 
     As described above, in LTE Rel-10, the subframe designated for MBSFN transmission may be used in unicast transmission only for the TM9 UE. That is, the subframe is reserved as MBSFN subframe in the MBSFN-SubframeConfigList IE of SIB2, it may be used for unicast. Such a subframe may overlap with Transmission Time Interval (TTI) in which downlink scheduling (DL assignment) occurs by Semi-Persistent Scheduling (SPS). In this case, an appropriate UE operation is required. 
     It increases signaling overhead to provide scheduling information on every transmission of data burst for the traffic requiring periodic radio resource allocation such as VoIP. Accordingly, a scheduling technique for providing the user equipment (UE), in advance, with the scheduling information allocating radio resource periodically in order for the UE to transmit data on the radio resource allocated periodically is referred to as Semi-Persistent Scheduling (SPS). 
     SPS is applicable to PCell but not SCell in a Carrier Aggregation (CA) mode. 
       FIG. 5  is a signal flow diagram illustrating a procedure of activating and deactivating SPS. 
     The SPS is activated and deactivated using RRC signaling and PDCCH basically. 
     If the UE  500  wants to receive the service generating data periodically such as VoIP, the eNB  505  transmits RRCConnectionReconfiguration message including IE SPS-Config at step  510 . The corresponding IE includes SPS C-RNTI information, SPS interval, number of HARQ process, implicitReleaseAfter, etc. necessary for performing SPS. 
     Here, SPS C-RNTI is used for indicating the scheduling information for initial SPS transmission and retransmission. The SPS interval indicates the interval of allocating radio resource. The implicitReleaseAfter is described in association with the SPS deactivation procedure. The SPS activation is performed in such a way that the eNB sends the UE the SPS C-RNTI and E-PDCCH including New Data Indicator (NDI) set to 0 at step  515 . The NDI is used to distinguish between initial transmission and retransmission and described using an example with reference to  FIG. 6 . 
     The UE starts SPS using the received SPS-Config information at step  520 . 
     The UE transmits data suing the radio resource allocated periodically at step  525 . In the state of transmitting data, if data transmission error occurs and thus retransmission is required, the eNB performs radio resource scheduling for retransmission separately in downlink. In uplink, however, retransmission is performed on the pre-designated radio resource. The retransmission-related operation is described with reference to  FIG. 6 . 
     If it is required to stop applying SPS, the eNB deactivates SPS at operation  530 . For this purpose, the eNB uses IE SPS-Config in the RRCConnectionReconfiguration message. The RRC signaling-based SPS activation/deactivation is applicable to both the downlink and uplink. 
     It is also possible to deactivate SPS implicitly using implicitReleaseAfter information. The implicitReleaseAfter is set to an integer of {2, 3, 4, 8} and, if MAC PDUs containing no MAC SDU, due to no data to transmit in the uplink data transmission process, occur as much as indicated by implicitReleaseAfter, the UE deactivates SPS implicitly. 
       FIG. 6  is a diagram illustrating SPS operation and retransmission method in downlink. If SPS operation is activated, although the radio resource for downlink data transmission is allocated periodically, the eNB has to allocate the radio resource for retransmission separately. For this purpose, the system uses NDI and HARQ process ID. The two IEs are sent to the UE in PDCCH along with SPS C-RNTI. 
     In the SPS operation, the New Data Indicator (NDI) is used for distinguishing between SPS initial transmission and retransmission. That is, if NDI is set to 0, this indicates SPS initial transmission. Otherwise if NDI is set to 1, this indicates that the corresponding scheduling information is for retransmission. 
     Meanwhile, the HARQ process ID is used to identify the data transmission for which the downlink scheduling (DL assignment) information is transmitted. Whenever data transmission occurs on the periodically allocated radio resource, the HARQ process ID increments by 1 and this is used to instruct the transmission of the corresponding data. 
     After receiving the RRCConnectionReconfiguration message including IE SPS-Config and activating the SPS operation, the UE receives PDCCH including SPS C-RNTI and NDI set to 0 at step  600 . On the PDSCH corresponding to the PDCCH, the initial SPS transmission occurs. 
     However, if a transmission error occurs and thus the UE sends the eNB a NACK, the eNB sends the UE the scheduling information for retransmission at step  605 . At this time, the SPS C-RNTI, HARQ process ID set to 0, and NDI set to 1 are included in PDCCH. The HARQ process ID indicates that the corresponding scheduling information is the retransmission downlink scheduling (DL assignment) information on the data transmitted at step  600 . Also, the NDI indicates that the corresponding scheduling information is of retransmission. 
     At step  610 , a new transmission corresponding to the periodic radio resource occurs. The scheduling information for retransmission is sent to the UE at operation  615 . The UE is aware of the retransmission-related scheduling information based on the NDI set to 1 and determines, based on the HARQ ID, whether the scheduling information is the retransmission downlink scheduling (DL assignment) information on the first data or the retransmission downlink scheduling (DL assignment) information on the second data. 
     At step  620 , the scheduling information for retransmission is sent to the UE again. At this time, since the HARQ process ID is set to 1, the scheduling information is the downlink scheduling (DL assignment) information corresponding to the second data transmission. The third data transmission occurs at step  625 . 
     As described above, the subframe designated for MBSFN transmission may be used in unicast transmission only for the TM9 UE and may overlap with TTI of downlink scheduling (DL assignment) of SPS. 
     The present invention proposes the UE operation appropriate for such a situation. The present invention also includes a procedure in which the UE provides the eNB of MBMS counting information such that the eNB is capable of determining the frequency or cell for providing a certain MBMS service. 
     When the TTI of scheduling (assignment) caused by SPS matches the MBSFN subframe in downlink, the TM9 UE has no need to process the downlink scheduling (DL assignment) but non-TM9 UE which is not capable of using the MBSFN subframe for unicast transmission ignores the downlink scheduling (DL assignment). 
     If it is necessary for the TM9 UE to process PMCH in the corresponding MBSFN subframe, the TM9 UE ignores the downlink scheduling (DL assignment). If it is not necessary for the TM9 UE to process PMCH in the MBSFN subframe, it has to process the downlink scheduling (DL assignment). 
       FIG. 7  is a flowchart illustrating an operation procedure of the UE according to an embodiment of the present invention. 
     The UE performs RRC connection establishment at step  700 . The UE receives MBSFN-SubframeConfigList in the SIB2 message of the PCell at operation  705 . 
     The UE determines whether it is necessary to receive MBMS, according to the user&#39;s intention, at step  710 . If it is necessary to receive MBMS, the UE receives the first message broadcast by the eNB at operation  715 . The first message may be transmitted in the form of System Information (SI) and include information MBMS services provided on the frequencies of serving and neighbor cells. For example, the identifiers of the MBMS services provided by the serving and neighbor cells may be provided as sorted by frequency. 
     The UE determines whether the interested MBMS service is provided by the serving cell or neighbor cell (i.e. current cell or neighbor frequency) at step  720 . It so, the UE sends the eNB an MBMS counting response message as the second message at operation  725 . The second message includes the information related to the frequency on which the interested MBMS service is provided. For example, this corresponds to the information on whether the UE-interested MBMS service is provided by the serving cell, i.e. the frequency on which the UE-interested MBMS service is provided is the serving frequency. 
     The UE detects that the downlink scheduling (DL assignment) occurs at the current TTI at step  730 . This assumes that the DL SPS is activated at a certain time and any downlink scheduling (DL assignment) configured by the activated SPS occurs at current TTI. Of course, the above operation is valid when the current serving cell is the PCell. 
     Then the UE determines whether the TTI corresponds to a measurement gap at operation  735 . The measurement gap is the duration in which the serving cell performs no transmission in order for the UEs in the neighbor cell to perform measurement on the corresponding frequency. 
     If it is the measurement gap, the UE ignores the downlink scheduling (DL assignment) information at step  760 . 
     Otherwise if it is not the measurement gap, the UE determines whether the TTI corresponds to MBSFN subframe at operation  740 . Whether it is the MBSFN subframe may be checked by referencing the MBSFN subframe configuration list (Mbsfn-SubframeConfigList). 
     If it is not MBSFN subframe, the UE processes the downlink scheduling (DL assignment) at operation  755 . 
     If it is MBSFN subframe, the UE determines whether the corresponding subframe carries the interested MBMS service at operation  745 . If the interested MBMS service is included, the UE ignores the corresponding downlink scheduling (DL assignment) at operation  760 . 
     Otherwise, if the interested MBMS service is not included, the UE determines whether the UE is configured in the TM9 at operation  750 . 
     If it is not configured in TM9, this means that the MBSFN subframe cannot be used for unicast and the UE ignores the downlink scheduling (DL assignment) at operation  760 . 
     Otherwise if it is configured in TM9, the UE processes the downlink scheduling (DL assignment) at operation  755 . 
     Returning to  FIG. 720 , if the interested MBMS service is not provided in the current cell or on the neighbor frequencies, the UE detects that the occurrence of downlink scheduling (DL assignment) configured at current TTI at operation  765 . The above operation is valid when the current serving cell is the PCell. 
     The UE determines whether the TTI corresponds to the measurement gap at step  770 . 
     If it is the measurement gap, the UE ignores the downlink scheduling (DL assignment) information at step  785 . 
     If it is not the measurement gap, the UE determines that it is configured in TM9 at operation  775 . 
     If it is configured in TM9, the UE processes the downlink scheduling (DL assignment) at operation  790 . 
     Otherwise if it is not configured in TM9, the UE determines whether the current TTI corresponds to an MBSFN subframe at step  780 . The UE may check the MBSFN subframe configuration list (Mbsfn-SubframeConfigList) received in the SIB2 to verify the MBSFN subframe. 
     If the current TTI is the MBSFN subframe, the UE ignores the downlink scheduling (DL assignment) at step  785 . Otherwise if the current TTI is not MBSFN subframe, the UE processes the downlink scheduling (DL assignment) at operation  790 . 
     If it is determined that the UE is configured in TM9 at step  775 , the UE processes the downlink scheduling (DL assignment) immediately. However, instead of the downlink data, the MBSFN service may be transmitted at the corresponding TTI. In this case, there may be transmission error in the processed downlink scheduling (DL assignment) such that the UE may send the eNB a NACK. Since the eNB is retransmitting the corresponding data, it is not any operation error. 
     According to another embodiment of the present invention, although the UE determines whether the TTI is MBSFN subframe by referencing the MBSFN subframe configuration list (Mbsfn-SubframeConfigList) received in SIB2, the subframe indicated as MBSFN subframe in the MBSFN subframe configuration list (Mbsfn-SubframeConfigList) may be used for the purpose of unicast. 
     Accordingly, after determining whether the subframe carries MBSFN service finally at step  430  of  FIG. 4 , it is possible to process the downlink scheduling (DL assignment) at step  785 . 
       FIG. 8  is a diagram for explaining an MBMS counting request/response procedure in detail. 
     The MBMS counting request/response procedure has been mentioned at steps  715  and  725  of  FIG. 7 . In more detail, the eNB  805  provides the UE  800  with the MBMS service information at operation  815 . This information is broadcast in the form of System Information (SI), legacy SIB or newly defined SIB. The corresponding message is a COUNTING REQUEST message transmitted to a plurality of unspecific UEs. The COUNTING REQUEST message may be transmitted through MCCH and include following informations. 
     (1) MBMS service identifier 
     (2) information on frequency layer providing or to be used for providing MBMS service 
     The above message may include only the list of frequencies for providing MBMS service, the MBMS service provided through a certain frequency may be determined by the UE through a certain method, e.g. based on MBMS service guide information provided to the UE. The eNB transmits the COUNTING REQUEST message through the cells operating on all frequency layers. 
     If the message is received from the eNB and if the UE is receiving or wants to the corresponding MBMS service, it may send the eNB a COUNTING RESPONSE message. For this purpose, the UE sends the eNB an MBMS COUNTING RESPONSE message at step  820 . 
     The MBMS COUNTING RESPONSE message includes the information on the frequency for providing UE-interested MBMS service. In detail, the UE served by a cell of the frequency layer which does not provide the MBMS service may indicates this in the COUNTING RESPONSE message, which may include the following informations. 
     (1) Identifier of MBMS service which is currently received or wanted to receive among the MBMS services included in the COUNTING REQUEST message 
     Information indicating whether the frequency layer on which the MBMS service received currently or wanted to receive is provided is the serving frequency (In the case that Carrier aggregation is configured, it may indicate whether the frequency layer is the frequency layer of the PCell or SCell). 
     The eNB generates an MBMS Service Counting Results Report based on the information included in the COUNTING RESPONSE message received in the cells control by it at step  825 . This message include following informations. 
     (1) number of UEs which is interested in or receiving the corresponding MBMS service, per MBMS service 
     (2) number of UEs having the frequency layer providing the MBMS service thereon as the serving frequency and number of UEs having that frequency layers as non-serving frequencies among the UEs which are interested in or receiving the corresponding MBMS service, per MBMS service. 
     According to another embodiment of the present invention, the following information may be included. 
     (3) number of UEs which are interested in or receiving the corresponding MBMS service per frequency layer 
     The eNB sends the Multi-cell/multicast Coordination Entity (MCE) the MBMS Service Counting Results at operation  830 . Then the MCE performs necessary operation based on the counting result at step  835 . For example, if there are too may UEs to perform inter-frequency handover for receiving a certain MBMS service, MCE may determine to provide the MBMS service on multiple frequency layers and perform the process required for this. 
       FIG. 9  is a block diagram illustrating a configuration of the UE according to an embodiment of the present invention. 
     The UE transmits and receives data to and from higher layers  910  and transmits and receives controls messages through the control message processor  915 . When the UE transmits a control signal or data to the eNB, the control signal or data are multiplexed by the multiplexer/demultiplexer  905  and then transmitted through the transceiver  900  under the control of the controller. In reception mode, the UE receives physical signal by means of the transceiver  900 , demultiplexes the received signal by means of the modulator/demodulator  905 , and delivers the demodulated signal to the higher layer processor  910  or the control message processor  915 . 
     Although the drawing is directed to the case where the UE includes a plurality of blocks responsible for different functions, this is just an exemplary embodiment and the present invention is not limited thereto. For example, the functions of the multiplexer/demultiplexer  905  may be performed by the controller  920 . 
     In this case, the controller  920  may detects the occurrence of downlink scheduling at a certain Transmission Time Interval (TTI). The controller  920  determined whether to process the downlink scheduling depending on whether the UE is configured in TM9 or the TTI matches the MBSFN (Multimedia Broadcast multicast service Single Frequency Network) subframe. The controller  920  controls the UE to process or ignore the downlink scheduling according to the determination result. 
     In more detail, the controller  920  determines whether the TTI matches the measurement gap and, if so, controls to ignore the downlink scheduling. 
     If the TTI does not match the measurement gap, the controller  920  determines whether the UE is configured in TM9 and, if not configured in TM9, determines whether the TTI matches an MBSFN subframe and, if so, controls to ignore the downlink scheduling. 
     If the TTI does not match any MBSFN subframe, the controller  920  controls to process the downlink scheduling. 
     If the UE is configured in TM9, the controller  920  controls to process the downlink scheduling. 
       FIG. 10  is a block diagram illustrating a configuration of the eNB according to an embodiment of the present invention. As shown in  FIG. 10 , the eNB of the present invention includes a transceiver  1005 , a controller  101 , a multiplexer/demultiplexer  1020 , a control message processor  1035 , higher layer processors  1025  and  1030 , and a scheduler  1015 . 
     The transceiver  1005  transmits data and control signals on downlink carriers and receives data and control signals on uplink carriers. In the case that a plurality of carriers is configured, the transceiver  1005  may transmit and received data and control signals over a plurality of carriers. 
     The multiplexer/demultiplexer  1020  multiplexes the data generated by higher layer processors  1025  and  1030  and the control message processor  1035  and demultiplexes the data received through the transceiver  1005  and delivers the demultiplexed data to the higher layer processors  1025  and  1030 , control message processor  1035 , and/or the controller  1010 . The control message processor  1035  may takes an action necessary for processing the control message transmitted by the UE and delivers the controls message to be transmitted to the UE to the higher layer. 
     The higher layer processors  1025  and  1030  may be formed per UE per service and processes the data generated in the user service such as FTP and VoIP to transfer the processed data to the multiplexer/demultiplexer  1020  or processes the data output from the multiplexer/demultiplexer  1020  to transfer the processed data to the service applications of the higher layer. 
     The control unit  1010  determines the timing of MBMS transmission and control the transceiver for MBMS transmission. 
     The scheduler  1015  allocates transmission resource to the UE at an appropriate timing in consideration of the buffer state, channel state, and active time of the UE and controls the transceiver to process the signal transmitted by or to be transmitted to the UE. 
     The specification and drawings are to be regarded in an illustrative rather than a restrictive sense in order to help understand the present invention. It is obvious to those skilled in the art that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention.