Abstract:
The disclosure is related to a method and used in a user equipment that supports Device to Device transmission in Time Division Duplex system and a user equipment thereof. In one embodiment, UE receives downlink signaling to obtain a first configured frame structure, or determining a first configured frame structure by itself in step 1, and transmits a first D2D signaling to indicate the first configured frame structure in step 2; wherein the first configured frame structure indicates a uplink or downlink direction for all the subframes within one radio frame. The technical solution of the disclosure solves the problem of interference of the downlink signals for the UEs configured with different frame structures in D2D communication in eIMTA scenario.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/CN2014/079474, filed on Jun. 9, 2014, and claims benefit to Chinese Patent Application No. CN 201310236734.5, filed on Jun. 13, 2013, all of which is hereby incorporated by reference for all purposes. The International Application was published in China on Dec. 18, 2014 as WO2014198207 A1 under PCT Article 21 (2). 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The disclosure is related to a subframe scheduling scheme in the Time Division Duplex (TDD) system, and more particular to a subframe scheduling scheme in the TDD system of the Long Term Evolution (LTE) Device to Device (D2D) configuration. 
         [0004]    2. Related Art 
         [0005]    The traditional LTE system of 3rd Generation Partnership Project (3GPP) defines the frame structure of the TDD system, as shown in Table 1, in which D indicates downlink subframe, U indicates uplink subframe, S indicates special subframe. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 TDD LTE frame structure 
               
             
          
           
               
                 TDD 
                   
                   
               
               
                 UL/DL 
                 DL-UL 
               
               
                 frame 
                 switch point 
                 Subframe Index 
               
             
          
           
               
                 structure 
                 period 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
               
                 #0 
                 5 ms 
                 D 
                 S 
                 U 
                 U 
                 U 
                 D 
                 S 
                 U 
                 U 
                 U 
               
               
                 #1 
                 5 ms 
                 D 
                 S 
                 U 
                 U 
                 D 
                 D 
                 S 
                 U 
                 U 
                 D 
               
               
                 #2 
                 5 ms 
                 D 
                 S 
                 U 
                 D 
                 D 
                 D 
                 S 
                 U 
                 D 
                 D 
               
               
                 #3 
                 10 ms  
                 D 
                 S 
                 U 
                 U 
                 U 
                 D 
                 D 
                 D 
                 D 
                 D 
               
               
                 #4 
                 10 ms  
                 D 
                 S 
                 U 
                 U 
                 D 
                 D 
                 D 
                 D 
                 D 
                 D 
               
               
                 #5 
                 10 ms  
                 D 
                 S 
                 U 
                 D 
                 D 
                 D 
                 D 
                 D 
                 D 
                 D 
               
               
                 #6 
                 5 ms 
                 D 
                 S 
                 U 
                 U 
                 U 
                 D 
                 S 
                 U 
                 U 
                 D 
               
               
                   
               
             
          
         
       
     
         [0006]    In the traditional 3GPP version, the data communication occurs between the base station and the user equipment (UE). In 3GPP R (Release) 12, D2D communication is approved and discussed. The essential characteristics of D2D is to allow data transfer between the UEs. For FDD and TDD system, 3GPP has concluded that the UE is not allowed for simultaneous receiving and transmitting in D2D system in the RAN1 (Radio Access Network Working Group 1) #73 meeting. Furthermore, for avoiding the interference of the downlink data on D2D communication, the UE occupies the uplink subframe of the subframe (TDD) for D2D communication. The downlink subframe needs further discussion. 
         [0007]    The other important issue about TDD system in 3GPP R12 is eIMTA (Enhanced Interference Traffic Adaptation). The frame structure of the traditional TDD system is configured via SIB (System Information Block), and the shortest configuration period is 640 ms (millisecond). eIMTA allows TDD system to adjust the frame structure dynamically (10 millisecond period). RAN1 #73 meeting concluded that the common physical layer signaling is used to dynamically configure the frame structure of the current frame. For 3GPP R12 and the previous LTE system, the optional range of SIB and the fame structure configured by the common physical layer signaling is TDD UL/DL frame structure #{0,1,2,3,4,5,6}. 
         [0008]    Therefore, the D2D solution needs to support eIMTA scenario. One typical scenario is that two UEs performing D2D communication are in the coverage of the different service cells (or one is within the coverage of the service cell and the other one is outside the coverage of the service cell). At this point it requires studying how to perform the resource allocation for D2D communication. 
       SUMMARY 
       [0009]    One principle for D2D resource allocation is to pretect the D2D user equipment (UE) from the downlink interference generated by the system equipment. Based on the inventor&#39;s research, it is found that in some specific scenarios the two UEs performing D2D communication may experience interference from the different downlink equipments. Two scenarios below are the examples for the two user equipments UE1, UE 2 performing D2D communication. 
         [0010]    Scenario I: UE1 and UE 2 are respectively camping on the two service cells with different frame structures. 
         [0011]    Scenario II: UE1 is under the service cell&#39;s coverage while UE2 is outside the coverage of the service cell (i.e. UE2 is not interfered by the downlink signals). 
         [0012]    The disclosure provides a unified solution for the different scenarios. 
         [0013]    The disclosure provides a method used in a user equipment that supports Device to Device transmission in Time Division Duplex system. The method comprises receiving a downlink signaling to obtain a first configured frame structure, or determining a first configured frame structure by itself; and transmitting a first D2D signaling to indicate the first configured frame structure. 
         [0014]    In one embodiment, the first configured frame structure indicates an uplink or downlink direction for all the subframes within one radio frame. 
         [0015]    The step of receiving a downlink signaling to obtain a first configured frame structure is applicable for the user equipment within the network coverage. That is, the user equipment is able to receive the downlink configured frame structure signaling from the service cell. There are two types of the downlink signaling in LTE network, which are System Information Block (SIB) and the common physical layer signaling. The former is suitable for a traditional scenario, and the latter is suitable for eIMTA scenario. 
         [0016]    The step of determining a first configured frame structure by itself is applicable for the user equipment outside of the network coverage. That is, the user equipment can not reliably receive the data from the service cell or the user equipment does not search out the accessible cells. Therefore, the user equipment needs to determine the first configured frame structure by itself. 
         [0017]    Specifically, according to one aspect of the disclosure, the first D2D signaling is a physical layer signaling. 
         [0018]    To support eIMTA, the user equipment in D2D communication needs to dynamically inform the paired user equipment in D2D communication of the status of its frame structure. 
         [0019]    Specifically, according to one aspect of the disclosure, when the UE determines the first configured frame structure by itself, the first configured frame structure is configured as uplink frame structure. 
         [0020]    For the user equipment outside of the network coverage, it is not interfered by the downlink signals of the service cell. Therefore, all the subframes may be suitable for receiving the D2D signals. 
         [0021]    Specifically, according to one aspect of the disclosure, the disclosure further comprises: 
         [0022]    receiving a second D2D signaling to obtain a second configured frame structure; 
         [0023]    wherein the second configured frame structure indicates a uplink or downlink direction for all the subframes within one radio frame. 
         [0024]    In one embodiment, the aforementioned aspects are suitable for D2D communication with the peer configuration. That is each user equipment needs to report its frame structure to the peer user equipment, and in the meanwhile needs to receive a signaling corresponding to the frame structure from the peer user equipment. For D2D communication with the master-slave configuration, the slave UE only needs to report its frame structure to the master UE through signaling without acquiring the frame structure of the master UE. 
         [0025]    In the D2D communication, the possible D2D communication resource scheduling (for example physical resource allocation, Hybrid Automatic Repeat Request (HARQ), retransmission resource allocation, power control, etc.) comprises the following approaches: 
         [0026]    Approach 1: the system controls all the resource scheduling; 
         [0027]    Approach 2: UE controls all the resource scheduling; 
         [0028]    Approach 3: the system and UE together control the resource scheduling. 
         [0029]    Approach 1 may require the excessive control signaling and may have larger delay. Approach 2 may generate a certain extent of interference on the non-D2D communication in the cell. Approach 3 is a reasonable solution. For example, the system allocates the frequency-domain resources, and the UE determines the time resources for D2D communication by itself. For Approach 2 and Approach 3, the UE is likely to determine the subframes available for D2D reception and D2D transmission. In eIMTA scenario of TDD, it is possible that the two UEs in D2D communication are configured with the different frame structures. Therefore, for a given UE, the available subframes for D2D reception may be different from the available subframes for D2D transmission. 
         [0030]    Specifically, according to one aspect of the disclosure, the disclosure further comprises: 
         [0031]    receiving the D2D signals in a subframe corresponding to the uplink subframe of the first configured frame structure. 
         [0032]    The essence of the above aspect is that the UE can only receive the D2D signals in the uplink subframe of the configured frame structure so as to avoid the downlink interference. 
         [0033]    Specifically, according to another aspect of the disclosure, the disclosure further comprises: 
         [0034]    selecting a suitable subframe out of the subframes corresponding to the UL subframe of the second configured frame structure; and 
         [0035]    transmitting the D2D signals on the suitable subframe. 
         [0036]    The essence of the above aspect is that (in order to assure that the D2D receiving UE may receive the D2D signals) the UE transmits the D2D signals on the selected (one or more) subframe (s), which is (are) configured as UL subframe (s) for the D2D receiving UE. In one embodiment, the UE selects the suitable subframe(s) by itself. In another embodiment, the UE selects the suitable subframe(s) according to the instruction of the downlink selection signaling. 
         [0037]    Specifically, according to one aspect of the disclosure, the UE receives the downlink signaling to obtain the first configured frame structure. The downlink signaling is SIB or a physical layer signaling. The first configured frame structure is one of TDD UL/DL frame structure #{0,1,2,3,4,5,6}. 
         [0038]    The disclosure provides a method used in UE that supports D2D transmission under TDD system, comprising: 
         [0039]    receiving a first D2D signaling to obtain a first configured frame structure; 
         [0040]    wherein the first configured frame structure indicates a uplink or downlink direction for all the subframes within one radio frame. 
         [0041]    Specifically, according to one aspect of the disclosure, the method further comprises: 
         [0042]    selecting one (or more) suitable subframe (s) corresponding to the UL subframe of the first configured frame structure; and 
         [0043]    transmitting the D2D signals on the suitable subframe(s). 
         [0044]    Specifically, according to one aspect of the disclosure, the first D2D signaling is a physical layer signaling. 
         [0045]    Specifically, according to one aspect of the disclosure, the first configured frame structure are configured as UL subframes; or the first configured frame structure is one of TDD UL/DL frame structure #{0,1,2,3,4,5,6}. 
         [0046]    The disclosure provides a user equipment (UE) comprising: 
         [0047]    a first module for receiving a downlink signaling to obtain a first configured frame structure, or determining a first configured frame structure by itself; and 
         [0048]    a second module for transmitting a first D2D signaling to indicate the first configured frame structure; 
         [0049]    wherein the first configured frame structure indicates a uplink or downlink direction for all the subframes within one radio frame. 
         [0050]    The UE comprises, but not limited to mobile phones, tablet computers, data cards, laptops, and etc. 
         [0051]    In one embodiment, the UE further comprises a third module for receiving a second D2D signaling to obtain a second configured frame structure; wherein the second configured frame structure indicates a uplink or downlink direction for all the subframes within one radio frame. 
         [0052]    In one embodiment, the UE further comprises 
         [0053]    a fifth module for selecting a suitable subframe(s) out of the subframes corresponding to the UL subframes of the second configured frame structure; and 
         [0054]    a sixth module for transmitting the D2D signal on the suitable subframe. 
         [0055]    In one embodiment, the UE further comprises a fourth module for receiving the D2D signal in one (or more) subframe(s) out of the subframes corresponding to the UL subframe of the first configured frame structure. 
         [0056]    The disclosure solves the problem that the UE in D2D communication cannot determine the subframe for D2D signal transmission in eIMTA scenario. Through allowing the UE to transmit the configured frame structure to assure the peer UE being able to determine the subframe(s) for transmitting D2D signal, the disclosure maximumly maintain the compatibility with the existing systems. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0057]    The above and other exemplary aspects, features and advantages of certain exemplary embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0058]      FIG. 1  is a schematic diagram illustrating two UE in D2D communication camping on two different service cells respectively according to one embodiment of the present disclosure; 
           [0059]      FIG. 2  is a schematic diagram illustrating one UE in D2D communication is in the coverage of the service cell and the other UE in D2D communication is outside the coverage of the service cell according to one embodiment of the present disclosure; 
           [0060]      FIG. 3  is a schematic diagram illustrating two UE in D2D communication at the same service cell according to one embodiment of the present disclosure; 
           [0061]      FIG. 4  is a schematic flow chart illustrating the D2D communication according to one embodiment of the present disclosure; 
           [0062]      FIG. 5  is a block diagram illustrating the device transmitting the configured frame structure signaling in an user equipment according to one embodiment of the present disclosure; and 
           [0063]      FIG. 6  is a block diagram illustrating the device receiving the configured frame structure signaling in a user equipment according to one embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0064]    The following description with reference to the accompanying drawings is provided to explain the exemplary embodiments of the disclosure. Note that in the case of no conflict, the embodiments of the present disclosure and the features of the embodiments may be arbitrarily combined with each other. 
       Embodiment I 
       [0065]    Embodiment I illustrates two UEs in D2D communication located at two different service cells, as shown in  FIG. 1 . In  FIG. 1 , the first UE  30  is in the coverage of the first service cell  10 , and the second UE  40  is in the coverage of the second service cell  20 . The first UE  30  and the second UE  40  perform D2D communication. 
         [0066]    For the first UE  30 , in Step S 103 , the first UE  30  receives the SIB signaling of the first service cell  10  to obtain the configured frame structure of the first cell  10 . In Step  304 , the D2D signaling is transmitted to the second UE  40  to indicate the configured frame structure of the first cell  10 . In Step S 403 , the D2D signaling from the second UE  40  is received to obtain the configured frame structure of the second cell  20 . 
         [0067]    For the second UE  40 , in Step S 204 , the common physical layer signaling of the second service cell  20  is received to obtain the configured frame structure of the second service cell  20 . In Step  403 , the D2D signaling is transmitted to the first UE  30  to indicate the configured frame structure of the second cell  20 . In Step  304 , the D2D signaling from the first UE  30  is received to obtain configured frame structure of the first cell  10 . 
         [0068]    In Embodiment I, the configured frame structure is TDD UL/DL frame structure, which is one of TDD UL/DL frame structure #{0,1,2,3,4,5,6}. 
       Embodiment II 
       [0069]    Embodiment II illustrates that one UE in D2D communication is in the coverage of the service cell and the other UE in D2D communication is outside the coverage of the service cell, as shown in  FIG. 2 . In  FIG. 2 , the first UE  30  is in the first service cell  10 , and the second UE  40  is outside of the service cell. The first UE  30  and the second UE  40  perform D2D communication. 
         [0070]    For the first UE  30 , in Step S 103 , the first UE  30  receives the SIB signaling of the first service cell  10  to obtain the configured frame structure of the first cell  10 . In Step  403 , the signaling from the second UE  40  is received to obtain the configured frame structure of the second UE  40 . 
         [0071]    For the second UE  40 , in Step  404 , the frame structure of the second UE  40  is determined as uplink frame structure. The Step  404  is completed in the second UE  40 . In Step S 403 , a signaling is transmitted to the first UE  30  to indicate the configured frame structure of the second UE  40 . In Embodiment II, the first UE  30  is master, and the second UE  40  is slave. 
       Embodiment III 
       [0072]    Embodiment III illustrates that the two UEs in D2D communication are at the same cell, as shown in  FIG. 3 . In  FIG. 3 , the service cell for the third UE  60  and the forth UE  80  is the third service cell  50 . 
         [0073]    For the forth UE  80 , in Step S 401 , the forth UE  80  receives receives the SIB signaling of the third cell  50  to obtain the configured frame structure of the third cell  50 , which is TDD UL/DL frame structure # 0 . In Step S 601 , the forth UE  80  receives the D2D signaling from the third UE  60  to obtain the configured frame structure of the third UE  60 , which is TDD UL/DL frame structure # 4 . In Step S 801 , the forth UE  80  transmits the D2D signaling to indicate the configured frame structure as TDD UL/DL frame structure # 0 . 
         [0074]    For the third UE  60 , in Step S 402 , the third UE  60  receives the downlink common physical layer signaling for eIMTA configured frame structure from the third cell to obtain the current configured frame structure of the third cell  50 , which is TDD UL/DL frame structure # 4 . In Step S 601 , the third UE  60  transmits the D2D signaling to indicate the configured frame structure as TDD UL/DL frame structure # 4 . In Step S 801 , the third UE  60  receives the D2D signaling from the forth UE  80  to obtain the configured frame structure of the forth UE  80 , which is TDD UL/DL frame structure # 0 . 
         [0075]    In Embodiment III, the forth UE  80  is a non eIMTA configured UE. The third UE  60  is an eIMTA configured UE. Although they are in the same service cell, the configured frame structures of the forth UE  80  and the third UE  60  are different. 
         [0076]    In another embodiment of Embodiment III, the D2D singling is a physical layer signaling. 
       Embodiment IV 
       [0077]    Embodiment IV illustrates the process of D2D communication, as shown in  FIG. 4 . In  FIG. 4 , the service cell for UE U 1  is N 1 , and the service cell for UE U 2  is N 2 . U 1  and U 2  perform D2D communication. In  FIG. 4 , the steps in the block F 1  and the steps in the block F 2  are optional. 
         [0078]    For U 1 , in Step S 21 , U 1  receives the first downlink signaling transmitted from N 1  to obtain the configured frame structure S 1 . In Step  22 , the first D2D signaling is transmitted to indicate the configured frame structure S 1 . In Step S 23 , the second D2D signaling is received to obtain the configured frame structure S 2 . 
         [0079]    For U 2 , in Step S 31 , U 2  receives the second downlink signaling transmitted from N 2  to obtain the configured frame structure S 2 . In Step S 32 , the first D2D signaling is received to obtain the configured frame structure S 1 . In Step S 33 , the second D2D signaling is transmitted to indicate the configured frame structure S 2 . 
         [0080]    In Embodiment IV, the downlink signaling is SIB. The configured frame structure is one of TDD UL/DL frame structure #{0,1,2,3,4,5,6}. 
         [0081]    In an alternative embodiment of Embodiment IV, in Step S 34 , UE U 2  selects a first subframe within the first subframe set (according to the instruction of N 2  or by itself). In Step S 35 , the first D2D signal is transmitted on the first subframe. In Step S 24 , UE U 1  receives the D2D signal on the first subframe. 
         [0082]    In the alternative embodiment of Embodiment IV, the first subframe set is a set composed of the subframes of the uplink subframe corresponding to S 1 . 
         [0083]    In an alternative embodiment of Embodiment IV, in Step S 25 , UE U 1  selects a second subframe within the second subframe set (according to the instruction of N 1  or by itself). In Step S 36 , the second D2D signal is transmitted on the second subframe. In Step S 36 , UE U 2  receives the D2D signal on the second subframe. 
         [0084]    In the alternative embodiment of Embodiment IV, the second subframe set is a set composed of the subframes of the uplink subframe corresponding to S 2 . 
       Embodiment V 
       [0085]    Embodiment V illustrates a block diagram illustrating the device transmitting the configured frame structure signaling in a user equipment, as shown in  FIG. 5 . In  FIG. 5 , the device  100  transmitting the configured frame structure signaling comprises a processing module  101 , a first transmitting module  102 , and a first receiving module  103 . The processing module  101  is for obtaining a first frame structure. For the UE within the coverage of the service cell, the processing module  101  obtains the first frame structure according to the downlink signaling of the service cell. For the UE outside of the coverage of the service cell, the processing module  101  determines the first frame structure as uplink frame structure itself. The first transmitting module  102  transmits the D2D signaling to indicate the first configured frame structure. The first receiving module  103  receives the D2D signal on the subframe of the uplink subframe corresponding to the first frame structure. 
         [0086]    In an alternative embodiment, the first frame structure is one of TDD UL/DL frame structure #{0,1,2,3,4,5,6}, which are uplink frame structure. 
       Embodiment VI 
       [0087]    Embodiment VI illustrates a block diagram illustrating the device receiving the configured frame structure signaling in a user equipment, as shown in  FIG. 6 . In  FIG. 6 , the device  200  receiving the configured frame structure signaling comprises a second receiving module  201 , a selecting module  202  and a second transmitting module  203 . The second receiving module  201  receives the D2D signaling to obtain the second frame structure. The selecting module  202  selects a suitable subframe from the subframes of the uplink subframes corresponding the second frame structure. The second transmitting module  203  transmits the D2D signal on the suitable subframe. 
         [0088]    In an alternative embodiment, the second frame structure is one of TDD UL/DL frame structure #{0,1,2,3,4,5,6}. 
         [0089]    Those of ordinary skill will be appreciated that all or part of the above method may be accomplished by a program instructing related hardware. The program may be stored in a computer-readable storage medium, such as read-only memory, a hard disk or CD-ROM. Alternatively, all or part of the steps of the above-described embodiments may be accomplished by one or more integrated circuits. Accordingly, each module in the above-described embodiments may be accomplished by hardware implementation, or may also be realized by the form of software modules. The present disclosure is not limited to any particular form of combination of software and hardware. 
         [0090]    Although the present disclosure is illustrated and described with reference to specific embodiments, those skilled in the art will understand that many variations and modifications are readily attainable without departing from the spirit and scope thereof as defined by the appended claims and their legal equivalents.