Patent Publication Number: US-2019191484-A1

Title: Communication system, reception device, and transmission device

Description:
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-242923, filed on Dec. 19, 2017, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present invention relates to a communication system which sends information with a predefined format to a reception device from a transmission device. 
     BACKGROUND ART 
     A User-plane protocol stack (hereinafter, referred to as a protocol stack) conforming to the 3GPP&#39;s LTE specification has a layered architecture which consists of PHY, MAC, and RLC layers and is constructed in a bottom-up manner (refer to Non-patent literature 1 shown below). Here, 3GPP is an abbreviation of Third Generation Partnership Project. Further, LTE is an abbreviation of Long Term Evolution. Further, PHY is an abbreviation of physical. Further, MAC is an abbreviation of Media Access Control. Furthermore, RLC is an abbreviation of Radio Link Control. 
     Further, a MAC-PDU structure is disclosed in Non-patent literature 2 shown below. Here, PDU is an abbreviation of Protocol Data unit. 
     For example, as an eNB for performing reception processing of a MAC-PDU, a configuration shown in  FIG. 1  may be used. Here, eNB is an abbreviation of E-UTRAN NodeB. Further, UTRAN is an abbreviation of Universal Terrestrial Radio Access Network. 
       FIG. 1  is a conceptual diagram illustrating a configuration of an eNB  404  that is a common eNB for performing reception processing of the MAC-PDU. 
     The eNB  404  includes an antenna-RF unit  441 , a PHY processing unit  442 , a MAC processing unit  443 , an RLC processing unit  444 , and a PDCP processing unit  445 . Here, PDCP is an abbreviation of Packet Data Convergence Protocol. 
     The antenna-RF unit  441  converts a wireless signal received in a wireless space into a signal for reception and sends it to the PHY processing unit  442 . The signal for reception is, for example, a baseband signal. 
     The PHY processing unit  442  is a CPU (Central Processing Unit) or the like for performing the processing of the PHY layer of the protocol stack. 
     The PHY processing unit  442  performs demodulation and decoding of the signal for reception inputted from the antenna-RF unit  441 . The PHY processing unit  442  obtains the MAC-PDU from the signal after demodulation and decoding and sends it to the MAC processing unit  443 . 
     The MAC processing unit  443  is a CPU or the like for performing the processing of the MAC layer of the protocol stack. 
     The MAC-PDU sent to the MAC processing unit  443  from the PHY processing unit  442  includes a MAC-Header and a MAC-Payload. 
     The MAC processing unit  443  obtains an LCID in the MAC-Header included in the MAC-PDU sent from the PHY processing unit  442 . Here, LCID is an abbreviation of Local Identifier. 
     The MAC processing unit  443  holds the LCID and data indicating a layer, that is either the MAC layer or the RLC layer, in which the content of the MAC-Payload has to be handled in advance. The data is disclosed on page 90 of Non-patent literature 2 shown below. 
     The MAC processing unit  443  determines the layer, that is either the MAC layer or the RLC layer, in which the content of the MAC-Payload has to be handled on the basis of the obtained LCID and the data. 
     Hereinafter, the MAC-Payload handled in the MAC layer is referred to as a MAC-Payload for MAC. The MAC-Payload for MAC does not have a format conforming to the standard for RLC. 
     Further, the MAC-Payload handled in the RLC layer is referred to as a MAC-Payload for RLC. The MAC-Payload for RLC has a format conforming to the standard for RLC. 
     The MAC-Payload for RLC is called a MAC SDU when it is viewed while focusing on the MAC. Here, SDU is an abbreviation of Service Data Unit. On the other hand, the MAC-Payload for RLC is called an RLC-PDU when it is viewed while focusing on the RLC. In the following description, the MAC-Payload for RLC, the MAC SDU, and the RLC-PDU are synonymous with each other. 
     When the MAC processing unit  443  determines that the obtained the MAC-Payload is the MAC-Payload for MAC, the MAC processing unit  443  processes the MAC-Payload. The details of the process are described in Non-patent literature 2 described below. 
     On the other hand, when the MAC processing unit  443  determines that the obtained MAC-Payload is the RLC-PDU, the MAC processing unit  443  sends the RLC-PDU to the RLC processing unit  444 . 
     The RLC processing unit  444  is a CPU or the like for processing the RLC layer of the protocol stack. 
     The RLC processing unit  444  converts the RLC-PDU transferred from the MAC processing unit  443  that has a format conforming to the standard for RLC into a PDCP-PDU that does not conform to the standard for RLC. The RLC processing unit  444  sends the PDCP-PDU to the PDCP processing unit  445 . 
     The PDCP processing unit  445  converts the PDCP-PDU sent from the RLC processing unit  444  into User-Data having a format to perform a subsequent process. The PDCP processing unit  445  sends the User-Data to a User-Data processing unit. 
     Further, an abbreviation of a term and an explanation of a term that are described in this section are also applied to the section of “Description of Embodiments”. 
     Non-Patent Literature 1 
     3GPP TS 36.300 V14.3.0 (2017-06), [searched on 29 Nov. 2017], Internet (http://www.etsi.org/deliver/etsi_ts/136300_136399/136300/14.03.00_60/ts_136300v140300p.pdf) 
     Non-Patent Literature 2 
     3GPP TS 36.321 V14.3.0 (2017-06), [searched on 29 Nov. 2017], Internet (http://www.etsi.org/deliver/etsi_ts/136300_136399/136321/14.03.00_60/ts_136321v140300p.pdf) 
     Non-Patent Literature 3 
     3GPP TR 38.802 V14.0.0 (2017-03) 5.5, [searched on 29 Nov. 2017], Internet (https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=3066) 
     When the MAC-PDU does not include the MAC-Payload for MAC and includes only the RLC-PDU, the MAC processing unit  443  shown in  FIG. 1  obtains the RLC-PDU from the MAC-PDU and performs only a process of transferring it to the RLC processing unit. In this case, if the number of transferring times of the RLC-PDU can be reduced, a throughput of a transfer process decreases and whereby, processing latency for user data in the eNB can be improved by the amount of reduction. 
     Here, in 5G NR (New Radio), a Carrier aggregation in which sixteen Carrier Components (CCs) are aggregated is being studied (refer to Non-patent literature 3 described above). In this case, it is assumed that the MAC-PDU is received for each CC and the MAC-PDU does not include the MAC-Payload for MAC and includes only the MAC-Payload for RLC in all the CCs. In the case, the MAC processing unit needs to perform the transfer process by the number of times calculated by multiplying sixteen (the number of the CCs) by the number of Users to be processed. Processing cycle consumption of the MAC processing unit and the processing latency for the User-Data increase by the transfer process by the above-mentioned calculated number of times. Accordingly, in 5G NR, the reduction of the number of transferring times is especially effective in improving the processing latency for the user data in the eNB. 
     SUMMARY 
     An example object of the present invention is to provide a communication system or the like which can improve processing latency in a reception device. 
     The communication system of the present invention is a communication system which includes a transmission device for performing transmission of a PDU that is a Protocol Data Unit including a Payload consisting of one or more data elements to a reception device and the reception device for performing reception of the PDU, wherein the transmission device performs transmission of a first PDU that is the PDU which includes only a first element that is the data element scheduled to be changed from a first format that conforms to a predetermined standard to a second format that does not conform to the standard by the reception device in an element storage area for storing the data element of the Payload and a second PDU that is the PDU which includes only a second element that is the data element not being the first element in the element storage area and the reception device extracts the first PDU and the second PDU from the received PDU, sends the first PDU to a first processing unit for processing the first PDU, and sends the second PDU to a second processing unit for processing the second PDU so that the first and second PDUs are processed in the first and second processing units separately, respectively. 
     The communication system or the like of the present invention can improve processing latency in the reception device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary features and advantages of the present invention will become apparent from the following detailed description when taken with the accompanying drawings in which: 
         FIG. 1  is a conceptual diagram illustrating an example of a configuration of a common eNB which performs reception processing of a MAC-PDU; 
         FIG. 2  is a conceptual diagram illustrating an example of a configuration of a communication system according to this example embodiment; 
         FIG. 3  illustrates an example of a structure of a MAC-PDU in which only Padding and Media Access Control Control Element are included in a MAC-Payload; 
         FIG. 4  is a table showing an example of a structure of each field included in a MAC-PDU; 
         FIG. 5  illustrates an example of a structure of a MAC-PDU in which only Padding and Common Control Channel are included in a MAC-Payload; 
         FIG. 6  illustrates an example of a structure of a MAC-PDU in which only Padding and RLC-PDU are included in a MAC-Payload; and 
         FIG. 7  is a conceptual diagram illustrating a minimum configuration of a communication system according to an example embodiment. 
     
    
    
     EXAMPLE EMBODIMENT 
     Next, a detailed explanation will be given for a first example embodiment with reference to the drawings. 
     Configuration and Operation 
       FIG. 2  is a conceptual diagram illustrating a configuration of a communication system  100  that is an example of a communication system according to this example embodiment. 
     The communication system  100  includes a User-Data generation unit  101 , a UE  202 , a propagation path  303 , an eNB  404 , and a User-Data processing unit  505 . 
     The UE  202  includes a PDCP-PDU generation unit  221 , an RLC-PDU generation unit  222 , a MAC-CE/CCCH generation unit  223 , a selection unit  224 , a MAC-PDU generation unit  225 , and an identification information assignment unit  226 . Further, the UE  202  includes a PHY processing unit  227  and an antenna-RF unit  228 . Here, “MAC-CE” is an abbreviation of Media Access Control Control Element. Further, “CCCH” is an abbreviation of Common Control Channel. 
     On the other hand, the eNB  404  includes the antenna-RF unit  441 , the PHY processing unit  442 , the MAC processing unit  443 , the RLC processing unit  444 , and the PDCP processing unit  445 . 
     The PHY processing unit  442  includes a sub-PHY processing unit  421  and an identification information processing unit  422 . 
     The MAC processing unit  443  includes a MAC-PDU processing unit  431  and a MAC-CE/CCCH processing unit  432 . 
     The RLC processing unit  444  includes a MAC-PDU processing unit  448  and an RLC-PDU processing unit  449 . 
     The User-Data generation unit  101  generates predetermined User-Data and sends it to the PDCP-PDU generation unit  221  of the UE  202 . 
     The PDCP-PDU generation unit  221  converts the User-Data sent from the User-Data generation unit  101  into the PDCP-PDU having a format conforming to the standard of PDCP and sends it to the RLC-PDU generation unit  222 . 
     The RLC-PDU generation unit  222  converts the PDCP-PDU sent from the PDCP-PDU generation unit  221  into the RLC-PDU conforming to the standard for RLC and sends it to the selection unit  224 . 
     The MAC-CE/CCCH generation unit  223  generates the MAC-CE and the CCCH. Here, the MAC-CE and the CCCH are disclosed in Non-patent literature 2 mentioned above. The MAC-CE and the CCCH belong to the MAC-Payload for MAC described in the section of “Background art”. The MAC-CE/CCCH generation unit  223  sends the generated MAC-CE or CCCH to the selection unit  224 . 
     The selection unit  224  holds the RLC-PDU sent from the RLC-PDU generation unit  222 , and the MAC-CE and the CCCH that are sent from the MAC-CE/CCCH generation unit  223 . Hereinafter, either of the RLC-PDU, the MAC-CE or the CCCH are defined as a Payload element. 
     The selection unit  224  selects a Payload element group (a plurality of Payload elements) to be subsequently sent to the MAC-PDU generation unit  225  from among the held Payload elements. When selecting the Payload element group, the selection unit  224  makes the selection so that the Payload element included in the selected Payload element group is either the RLC-PDU or one of the MAC-CE and the CCCH. 
     The selection unit  224  sends the selected Payload element group to the MAC-PDU generation unit  225 . 
     The MAC-PDU generation unit  225  stores the Payload element group sent from the selection unit  224  in a Payload element group storage area of the MAC-Payload, generates the MAC-PDU to which the MAC-Header is added, and sends it to the identification information assignment unit  226 . Here, the Payload element group storage area is an area in the MAC-Payload, excluding at least the area in which the Reserved and the Padding described in Non-patent literature 2 described above are stored. The Payload element is not stored in a Payload element group non-storage area that is an area other than the Payload element group storage area of the MAC-Payload. 
     When the MAC-PDU sent from the MAC-PDU generation unit  225  includes the RLC-PDU, the identification information assignment unit  226  stores first identification information in a predetermined storage position of the MAC-Header included in the MAC-PDU. A value of the first identification information is, for example, “1”. 
     The above-mentioned storage position is, for example, an R Header Field that is a head of a first MAC-Sub-Header included in the MAC-Header (refer to page 68 of Non-patent literature 2 mentioned above). 
     Further, when the MAC-PDU sent from the MAC-PDU generation unit  225  includes the MAC-CE or the CCCH, the identification information assignment unit  226  stores second identification information in the above-mentioned storage position. When the value of the first identification information is “1”, the value of the second identification information is “0”. 
     The identification information assignment unit  226  sends the MAC-PDU to which one of the first identification information and the second identification information is assigned to the PHY processing unit  227 . 
     Hereinafter, one of the first identification information and the second identification information is referred to as the identification information. 
     The PHY processing unit  227  converts the MAC-PDU sent from the identification information assignment unit  226  into a signal for transmission and sends it to the antenna-RF unit  228 . 
     The antenna-RF unit  228  converts the signal for transmission sent from the PHY processing unit  227  into wireless electrical wave and transmits it to the propagation path  303 . 
     The propagation path  303  includes, for example, a base station, a relay station, and the like. The wireless electrical wave transmitted by the antenna-RF unit  228  reaches the antenna-RF unit  441  of the eNB  404  through the propagation path  303 . 
     The antenna-RF unit  441  converts the recieved wireless electrical wave into the signal for reception and sends it to the sub-PHY processing unit  421  of the PHY processing unit  442 . 
     The sub-PHY processing unit  421  obtains the MAC-PDU from the signal for reception sent from the antenna-RF unit  441  and sends it to the identification information processing unit  422 . 
     The identification information processing unit  422  determines whether the identification information stored in the storage position of the MAC-Header included in the MAC-PDU sent from the sub-PHY processing unit  421  is the first identification information or the second identification information. 
     When the identification information is the first identification information, the identification information processing unit  422  sends the MAC-PDU sent from the sub-PHY processing unit  421  to the MAC-PDU processing unit  448  of the RLC processing unit  444 . 
     On the other hand, when the identification information is the second identification information, the identification information processing unit  422  sends the MAC-PDU sent from the sub-PHY processing unit  421  to the MAC-PDU processing unit  431  of the MAC processing unit  443 . 
     The MAC-PDU processing unit  431  sends the MAC-CE and the CCCH that are the MAC-Payload included in the MAC-PDU sent from the identification information processing unit  422  to the MAC-CE/CCCH processing unit  432 . 
     The MAC-CE/CCCH processing unit  432  performs processing of the content indicated by the MAC-CE or the CCCH sent from the MAC-PDU processing unit  431 . This processing is, for example, a predetermined control process performed on the basis of the MAC-CE or the CCCH that is a control signal. The details of the control process is described in Non-patent literature 2 described above. 
     The MAC-PDU processing unit  448  of the RLC processing unit  444  sends the RLC-PDU that is the MAC-Payload included in the MAC-PDU sent from the identification information processing unit  422  to the RLC-PDU processing unit  449 . 
     The RLC-PDU processing unit  449  converts the RLC-PDU sent from the MAC-PDU processing unit  448  into the PDCP-PDU that does not conform to the standard of the RLC and conforms to the standard of the PDCP and sends it to the PDCP processing unit  445 . 
     The PDCP processing unit  445  converts the PDCP-PDU sent from the RLC-PDU processing unit  449  into the User-Data that does not conform to the standard of the PDCP and has a format suitable for the process performed in the User-Data processing unit  505  and sends it to the User-Data processing unit  505 . 
     Next, an example of the MAC-PDU that is sent to the PHY processing unit  227  by the identification information assignment unit  226  shown in  FIG. 2  will be described. 
       FIG. 3  illustrates a structure of a MAC-PDU  901  that is an example of the MAC-PDU which includes only the Padding and the MAC-CE in the MAC-Payload. Here, the Padding is described on page 69 of Non-patent literature 2 mentioned above. 
     The MAC-PDU  901  includes a MAC-Header  902  and a MAC-Payload  903 . 
     The MAC-Payload  903  includes MAC-CEs  911  to  91 N that are N Payload elements and a Padding  91 P. 
     The MAC-Header  902  includes Sub-Headers  921  to  92 N that are N Sub-Headers and a Padding-Sub-Header  92 P. 
     The Sub-Headers  921  to  92 N correspond to the MAC-CEs  911  to  91 N, respectively. Specifically, each of the Sub-Headers  921  to  92 N corresponds to each of the MAC-CEs  911  to  91 N when the least significant digit of a reference number of the Sub-Headers  921  to  92 N is equal to the least significant digit of a reference number of the MAC-CEs  911  to  91 N. 
     Each Sub-Header consists of Header Fields R/F2/E/LCID (refer to page 68 of Non-patent literature 2 mentioned above). 
     A value (R value) of the R Header Field of the Sub-Header  921  is “0”. The R value of “0” indicates that the MAC-Payload of the MAC-PDU  901  does not include the RLC-PDU. “0” of the R value is a value of the second identification information that is stored by the identification information assignment unit  226  shown in  FIG. 2 . 
     Further, the Padding-Sub-Header  92 P is the Sub-Header corresponding to the Padding  91 P (refer to page 69 of Non-patent literature 2 mentioned above). 
       FIG. 4  is a table showing an example of the structure of each field included in the MAC-PDU  901  shown in  FIG. 3 . 
     Here, in the table of  FIG. 4 , the Sub-Header field, the Padding-Sub-Header field, the Payload element (MAC-CE) field, and the Padding field that are shown in  FIG. 3  are listed. In  FIG. 4 , it is assumed that the MAC-Payload  903  shown in  FIG. 3  includes only the MAC-CE  911  and the Padding  91 P. 
     In row No.  1  of the table shown in  FIG. 4 , it is indicated that a first Sub-Header corresponding to the MAC-CE that is a first Payload element consists of a data string of 8 bits and the values of the Header Fields R/F 2 /E/LCID are  0 / 0 / 1 / 11011 , respectively in this order. Here, the Header Fields R/F 2 /E/LCID are described on page 68 of Non-patent literature 2 mentioned above. Further, because the values of the Header Fields F 2 /E in row No.  1  are not directly relevant to the present invention, the explanation is omitted. 
     The R value of “0” indicates that the MAC-Payload of the MAC-PDU  901  does not include the RLC-PDU. “0” of the R value is a value of the second identification information that is stored by the identification information assignment unit  226  shown in  FIG. 2 . 
     Further, it is described that “11011” of the value of the Header Field of the LCID corresponds to the MAC-CE on page 90 of Non-patent literature 1 mentioned above. 
     In row No.  2  of the table shown in  FIG. 4 , it is indicated that the Padding-Sub-Header corresponding to the Padding consists of a data string of 8 bits and the values of the Header Fields R/F 2 /E/LCID are  0 / 0 / 0 / 11111 , respectively in this order. “11111” of the value of the Header Field LCID indicates the Padding. This is described on page 90 of Non-patent literature 2 mentioned above. Further, because each of the values of the Header Fields R/F 2 /E in row No.  2  is not directly relevant to the present invention, the explanation is omitted. 
     In row No.  3  of the table shown in  FIG. 4 , it is indicated that the first Payload element is the MAC-CE, and LCGID/Data-Size of the MAC-CE are 01/0000ffff, respectively in this order. Here, “LCGID” is an abbreviation of Logical Channel Group Identifier. This is described on pages 72 and 73 of Non-patent literature 2 mentioned above. 
     In row No.  4  of the table shown in  FIG. 4 , it is indicated that a number of consecutive bits of “0” are appended as the Padding and the number of consecutive 0s is equal to a value calculated by multiplying 8 by 5. 
       FIG. 5  illustrates a structure of a MAC-PDU  901   a  that is an example of the MAC-PDU which includes only the Padding and the CCCH in the MAC-Payload. 
     The MAC-PDU  901   a  includes a MAC-Header  902   a  and a MAC-Payload  903   a.    
     The MAC-Payload  903   a  includes a CCCH  911   a  that is the Payload element and the Padding  91 P. 
     The MAC-Header  902   a  includes a Sub-Header  921   a  and the Padding-Sub-Header  92 P. 
     The Sub-Header  921   a  corresponds to the CCCH  911   a.    
     The R value of the Sub-Header  921   a  is “0”. The R value of “0” indicates that the MAC-Payload of the MAC-PDU  901   a  does not include the RLC-PDU. “0” of the R value is a value of the second identification information that is stored by the identification information assignment unit  226  shown in  FIG. 2 . 
     Further, the Padding-Sub-Header  92 P is the Sub-Header corresponding to the Padding  91 P. 
       FIG. 6  illustrates a structure of a MAC-PDU  901   b  that is an example of the MAC-PDU which includes only the RLC-PDU in the MAC-Payload excluding the Padding. 
     The MAC-PDU  901   b  includes a MAC-Header  902   b  and a MAC-Payload  903   b.    
     The MAC-Payload  903   b  includes RLC-PDUs  911   b  to  91 Nb that are N Payload elements and the Padding  91 P. 
     The MAC-Header  902   b  includes Sub-Headers  921   b  to  92 Nb that are N Sub-Headers and the Padding-Sub-Header  92 P. 
     The Sub-Headers  921   b  to  92 Nb correspond to the RLC-PDUs  911   b  to  91 Nb, respectively. Specifically, each of the Sub-Headers  921   b  to  92 Nb corresponds to each of the RLC-PDUs  911   b  to  91 Nb when the value of the third digit (counting from left to right) of the reference number of the Sub-Header is equal to the value of the third digit (counting from left to right) of the reference number of the RLC-PDU. 
     The R value of the Sub-Header  921   b  is “1”. The R value of “1” indicates that the MAC-Payload of the MAC-PDU  901   b  includes only the RLC-PDU along with the Padding and a Reserved (not shown), in other words, the MAC-Payload does not include the MAC-CE and the CCCH. “1” of the R value is the value of the first identification information that is stored by the identification information assignment unit  226  shown in  FIG. 2 . 
     The Padding-Sub-Header  92 P is the Sub-Header corresponding to the Padding  91 P. 
     Further, in the above-mentioned description, a case of an Up-Link in which the User-Data is sent to the eNB from the UE has been explained as an example. However, in a case in which data is sent to the UE from the eNB, a similar configuration can be used. 
     In this case, the terms used in the above-mentioned description for explaining the operation of the communication system  100  should be changed as follows. 
     The words “User-Data”, “UE”, “User-Data generation unit”, “eNB”, and “User-Data processing unit” should be changed to “Data”, “eNB”, “Data generation unit”, “UE”, and “Data processing unit”, respectively in this order. 
     Effect 
     The transmission device of the communication system according to this example embodiment uses either the Payload element only for MAC or the Payload element only for RLC as the Payload element stored in the MAC-Payload of the MAC-PDU for transmissions. Further, the transmission device stores identification information indicating whether the Payload element is only for MAC or for RLC in the predetermined storage position of the MAC-Header of the MAC-PDU for transmissions. 
     The reception device of the communication system determines whether the Payload element stored in the MAC-Payload of the received MAC-PDU is only for MAC or for RLC by the identification information. The reception device sends the received MAC-PDU to either the MAC processing unit for performing a process related to the MAC or the RLC processing unit for performing a process related to the RLC on the basis of a determination result so that a process related to the MAC is performed by the MAC processing unit and a process related to the RLC is performed by the RLC processing unit separately. 
     Therefore, in the communication system, the transfer process in which the MAC processing unit of the reception device transfers the RLC-PDU to the RLC-PDU processing unit is not performed unlike the method described in the section of “Background art”. 
     Therefore, the communication system can improve the processing latency in the reception device that occurs in the transfer process in which the MAC processing unit transfers the RLC-PDU to the RLC-PDU processing unit. 
       FIG. 7  is a conceptual diagram illustrating a configuration of a communication system  100   x  that is a minimum configuration of the communication system according to this example embodiment. 
     The communication system  100   x  includes a transmission device  202   x  and a reception device  404   x.    
     The transmission device  202   x  performs transmission of the MAC-PDU including the MAC-Payload consisting of one or more data elements to the reception device. Here, “MAC-Payload” is an abbreviation of Media Access Control Payload. “MAC-PDU” is an abbreviation of Media Access Control Protocol Data Unit. 
     Further, the reception device  404   x  performs reception of the MAC-PDU. 
     The transmission device  202   x  performs transmission of a first MAC-PDU and a second MAC-PDU. Here, the first MAC-PDU is the MAC-PDU including only a first element in an element storage area for storing the data element of the MAC-Payload. The first element is the data element scheduled to be changed from the first format that conforms to the standard related to the RLC that is the Radio Link Control to the second format that does not conform to the standard by the reception device. Further, the second MAC-PDU is the MAC-PDU including only the second element that is the data element not being the first element in the element storage area. 
     The reception device  404   x  extracts the first MAC-PDU and the second MAC-PDU from the received MAC-PDU, sends the first MAC-PDU to a first processing unit, and sends the second MAC-PDU to a second processing unit so that the first and second MAC-PDUs are processed in the first and second processing units, respectively. 
     Therefore, in the communication system, the transfer process in which one processing unit of the reception device  404   x  receives the MAC-PDU and transfers the first MAC-PDU to another processing unit for performing a process related to the RLC is not performed unlike the method described in the section of “Background art”. 
     Therefore, the communication system  100   x  can improve the processing latency in the reception device  404   x  that occurs in the transfer process. 
     Therefore, because the communication system  100   x  has the above-mentioned configuration, the communication system  100   x  has an effect described in the section of “Advantageous Effects of Invention”. 
     Further, the communication system  100   x  shown in  FIG. 7  may be, for example, the communication system  100  shown in  FIG. 2 . Further, the transmission device  202   x  may be, for example, the UE  202  shown in  FIG. 2 . Further, the reception device  404   x  may be, for example, the eNB  404  shown in  FIG. 2 . Further, the first MAC-PDU may be, for example, the MAC-PDU for RLC. Further, the second MAC-PDU may be, for example, the MAC-PDU for MAC. Further, the first processing unit may be, for example, the RLC processing unit  444  shown in  FIG. 2 . Furthermore, the second processing unit may be, for example, the MAC processing unit  443  shown in  FIG. 2 . 
     Each example embodiment of the present application has been described above. However, the present invention is not limited to the example embodiment described above. Various changes, replacement, or adjustment can be applied to the configuration of each exemplary embodiment described above without departing from the basic technical idea of the present invention. For example, the configuration of the element shown in each drawing is shown as an example to give a better understanding of the present invention. Therefore, the configuration of the element is not limited to the configuration shown in these drawings. 
     The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes. 
     Supplementary Note 1 
     A communication system including a transmission device for performing transmission of a PDU that is a Protocol Data Unit including a Payload including one or more data elements to a reception device and the reception device for performing reception of the PDU, wherein the transmission device performs the transmission of a first PDU that is the PDU which includes only a first element that is the data element scheduled to be changed from a first format that conforms to a predetermined standard to a second format that does not conform to the standard by the reception device in an element storage area for storing the data element of the Payload and a second PDU that is the PDU which includes only a second element that is the data element not being the first element in the element storage area, and the reception device extracts the first PDU and the second PDU from the received PDU, sends the first PDU to a first processing unit for processing the first PDU, and sends the second PDU to a second processing unit for processing the second PDU so that the first and second PDUs are processed in the first and second processing units separately, respectively. 
     Supplementary Note 2 
     The communication system according to Supplementary note 1, in which the Payload is a Media Access Control Payload, the PDU is a Media Access Control PDU, and the standard is a standard related to an RLC that is a Radio Link Control. 
     Supplementary Note 3 
     The communication system described in Supplementary note 2 in which the first element includes an RLC-PDU. 
     Supplementary Note 4 
     The communication system described in Supplementary note 2 or Supplementary note 3 in which the second element includes a Media Access Control Control Element or a Common Control Channel. 
     Supplementary Note 5 
     The communication system described in any one of Supplementary notes 1 to 4 in which the data element is not stored in an element non-storage area that is an area not being the element storage area of the Payload. 
     Supplementary Note 6 
     The communication system described in Supplementary note 5 in which a Reserved and a Padding are stored in the element non-storage area. 
     Supplementary Note 7 
     The communication system described in any one of Supplementary notes 1 to 5 in which the transmission device assigns identification information indicating whether the PDU is the first PDU or the second PDU to the PDU to be transmitted. 
     Supplementary Note 8 
     The communication system described in Supplementary note 7 in which the transmission device stores the identification information in a Header included in the PDU. 
     Supplementary Note 9 
     The communication system described in Supplementary note 8 in which a storage position according to the storage is an R Header Field included in a Sub-Header that is a head of the Header. 
     Supplementary note 10 
     The communication system described in any one of Supplementary notes 7 to 9 in which the reception device extracts the first PDU and the second PDU from the received PDU on the basis of identification information. 
     Supplementary Note 11 
     The communication system described in any one of Supplementary notes 1 to 10 in which the first processing unit and the second processing unit are the devices separated from each other. 
     Supplementary Note 12 
     The communication system described in Supplementary note 11 in which the device is a central processing device. 
     Supplementary Note 13 
     A reception device which receives a first PDU that is a PDU being a Protocol Data Unit including a Payload including one or more data elements which includes only a first element that is the data element scheduled to be changed from a first format that conforms to a predetermined standard to a second format that does not conform to the standard in an element storage area for storing the data element of the Payload and a second PDU that is the PDU which includes only a second element that is the data element not being the first element in the element storage area that are transmitted from a transmission device, extracts the first PDU and the second PDU from the received PDU, sends the first PDU to a first processing unit for processing the first PDU, and sends the second PDU to a second processing unit for processing the second PDU so that the first and second PDUs are processed in the first and second processing units separately, respectively. 
     Supplementary Note 14 
     A transmission device which extracts a first PDU which includes only a first element that is a data element scheduled to be changed from a first format that conforms to a predetermined standard to a second format that does not conform to the standard in an element storage area for storing the data element of a Payload and a second PDU which includes only a second element that is the data element not being the first element in the element storage area from the received PDU that is a Protocol Data Unit including the Payload including one or more data elements, sends the first PDU to a first processing unit for processing the first PDU, and sends the second PDU to a second processing unit for processing the second PDU so that the first and second PDUs are processed in the first and second processing units separately, respectively. 
     Supplementary Note 15 
     A communication method for performing transmission of a PDU that is a Protocol Data Unit including a Payload including one or more data elements and performing reception of the PDU, wherein 
     the transmission is transmission of a first PDU that is the PDU which includes only a first element that is the data element scheduled to be changed from a first format that conforms to a predetermined standard to a second format that does not conform to the standard by the reception in an element storage area for storing the data element of the Payload and a second PDU that is the PDU which includes only a second element that is the data element not being the first element in the element storage area and 
     at the time of the reception, the first PDU and the second PDU are extracted from the received PDU, the first PDU is sent to one processing unit for processing the first PDU, and the second PDU is sent to another processing unit for processing the second PDU so that the first and second PDUs are processed in two different processing units separately, respectively. 
     REFERENCE SIGNS LIST 
       100  and  100   x  communication system 
       101  User-Data generation unit 
       202  UE 
       202   x  transmission device 
       221  PDCP-PDU generation unit 
       222  RLC-PDU generation unit 
       223  MAC-CE/CCCH generation unit 
       224  selection unit 
       225  MAC-PDU generation unit 
       226  identification information assignment unit 
       227  PHY processing unit 
       228  and  441  antenna-RF unit 
       303  propagation path 
       404  eNB 
       404   x  reception device 
       442  PHY processing unit 
       421  sub-PHY processing unit 
       422  identification information processing unit 
       443  MAC processing unit 
       431  MAC-PDU processing unit 
       432  MAC-CE/CCCH processing unit 
       444  RLC processing unit 
       445  PDCP processing unit 
       448  MAC-PDU processing unit 
       449  RLC-PDU processing unit 
       505  User-Data processing unit 
       901 ,  901   a,  and  901   b  MAC-PDU 
       902 ,  902   a,  and  902   b  MAC-Header 
       903 ,  903   a,  and  903   b  MAC-Payload 
       911 ,  911   a,    912 , and  91 N MAC-CE 
       911   b,    912   b,  and  91 Nb RLC-PDU 
       91 P Padding 
       921 ,  921   a,    921   b,    922 ,  922   a,    922   b,    92 N,  92 Na, and  92 Nb Sub-Header 
       92 P Padding-Sub-Header 
     The previous description of embodiments is provided to enable a person skilled in the art to make and use the present invention. Moreover, various modifications to these example embodiments will be readily apparent to those skilled in the art, and the generic principles and specific examples defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not intended to be limited to the example embodiments described herein but is to be accorded the widest scope as defined by the limitations of the claims and equivalents. 
     Further, it is noted that the inventor&#39;s intent is to retain all equivalents of the claimed invention even if the claims are amended during prosecution. 
     While the invention has been particularly shown and described with reference to example embodiments thereof, the invention is not limited to these embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the claims.