Patent Publication Number: US-2009232161-A1

Title: Hierarchical header format and data transmission method in communication system

Description:
TECHNICAL FIELD 
     The present invention relates to a hierarchical header format and a data transmission method in a communication system. 
     This work was supported by the IT R&amp;D program of MIC/IITA [2005-S-404-12, Research &amp; Development of Radio Transmission Technology for 3G Evolution]. 
     BACKGROUND ART 
     Communication systems require security of transmitted data. The security is more important in wireless communication systems than wired communication systems. The security is a function for preventing transmitted data from being lost or damaged. Various methods are used so as to prevent loss or damage in transmitted data in communication systems. One of the methods is the automatic repeat request (ARQ) method. The ARQ method is a method in which, when a receiver fails to receive predetermined data from a transmitter or fails to decode the data, the failure is notified to the transmitter so that the transmitter may transmit the data again. 
     The transmitter divides a service data unit (SDU) of a medium access control (MAC) protocol into ARQ blocks and transmits the same to the receiver. The receiver notifies the transmitter of the receiving status of the respective ARQ blocks. In this instance, the transmitter and the receiver must identify the transmitted blocks because it is possible to know which blocks the receiver has received and whether the receiver will request an ARQ for a predetermined block when they have identified the blocks. In order to identify the respective blocks, a block sequence number for identifying the transmitted blocks is applied to the respective blocks. 
     However, since the ARQ method transmits data in a fixed manner according to a predetermined transmission amount, radio resources may be wasted when there is not a large amount of transmitted data. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior alt that is already known in this country to a person of ordinary skill in the art. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     The present invention has been made in an effort to provide a header format for efficiently using radio resources and processing data at a high data rate in the case of transmitting data between layers in a communication system. 
     Technical Solution 
     In one aspect of the present invention, a method for transmitting data between layers in a communication system includes: determining a transmission method for a service packet according to quality of service (QoS) of the service packet; determining a transmission amount of the service packet according to the transmission method; fragmentizing and concatenating the service packet according to the transmission amount and generating at least one fragmentation block; generating a data packet including the at least one fragmentation block and information on the at least one fragmentation block; inserting information on the number of fragmentation blocks into the data packet; and transmitting the data packet. 
     The determining of a transmission method for a service packet includes selecting one of a transparent mode, an acknowledged mode, and an unacknowledged mode depending on the QoS requested by the service packet. 
     In another aspect of the present invention, a method for generating a data packet includes: fragmentizing and concatenating a service packet of an upper layer according to a transmission amount of a service packet, and generating at least one fragmentation block; inserting at least one fragmentation block information field corresponding to the at least one fragmentation block into the data packet; inserting the at least one fragmentation block into the data packet; and inserting information on the data packet into the data packet. 
     In another aspect of the present invention, a method for generating a transmission block includes: determining a transmission method for a service packet according to a quality of service (QoS) of the service packet; fragmentizing and concatenating the service packet according to a transmission amount of the service packet, and generating a fragmentation block; generating a data packet including the fragmentation block and information on the fragmentation block; generating a control packet for controlling data transmission according to the transmission method; generating the transmission block including the at least one data packet and the control packet; and inserting information on the transmission block into the transmission block. 
     According to the exemplary embodiments of the present invention, it is possible to efficiently use the radio resource and efficiently process data with a high data rate by using the hierarchical header format. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram for a communication system according to an exemplary embodiment of the present invention. 
         FIG. 2  is a flowchart for a data transmission method by an ARQ controller according to an exemplary embodiment of the present invention. 
         FIG. 3  is a configuration of a TB of a MAC layer and a header field of the TB according to an exemplary embodiment of the present invention. 
         FIG. 4  and  FIG. 5  show a first type and a second type of RLC PDU of a payload field of a TB according to an exemplary embodiment of the present invention. 
         FIG. 6  shows an RLC information field of an RLC PDU of a TB according to an exemplary embodiment of the present invention. 
         FIG. 7  and  FIG. 8  show a first type and a second type of FB information field of an RLC PDU of a TB according to an exemplary embodiment of the present invention. 
         FIG. 9  shows a configuration of an RLC control PDU according to an exemplary embodiment of the present invention. 
     
    
    
     MODE FOR THE INVENTION 
     In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
     Throughout this specification and the claims which follow, unless explicitly described to the contrary, the word “comprising” and variations such as “comprises” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. Also, the terms “unit”, “device”, and “module” in the present specification represent a unit for processing a predetermined function or operation, which can be realized by hardware, software, or a combination of hardware and software. 
     A hierarchical header format and a data transmission method in a communication system according to an exemplary embodiment of the present invention will be described. 
       FIG. 1  is a block diagram for a communication system  100  according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 1 , the communication system  100  includes a terminal information storage unit  110 , a packet controller  115 , and a scheduler/control protocol data unit (PDU) collector  117 , and the terminal information storage unit  110  includes a buffer  111  and an ARQ controller  113 . 
     The buffer  111  of the terminal information storage unit  110  receives an SDU from an upper layer and temporarily stores the SDU. 
     The ARQ controller  113  includes functions of a general radio link control (RLC) layer including a retransmission function for providing great data accuracy. Also, the ARQ controller  113  determines a data transmission mode based on the QoS of an SDU  200  stored in the buffer  111 . Here, the data transmission mode includes a transparent mode, an acknowledged mode, and an unacknowledged mode. 
     The transparent mode is generated when the ARQ controller  113  provides no overhead to the FB that is transmitted by an upper layer when generating an RLC PDU. Hence, the transparent mode is appropriate for services that have great requirements on the real-time transmission. 
     The acknowledged mode is generated when the ARQ controller  113  adds a PDU header including a sequence number (SN) to the payload of the PDU when generating the PDU, and a receiver responds to the PDU transmitted by a transmitter. The response is provided so that the receiver may request the transmitter to retransmit the PDU that is not received by the receiver. Since the acknowledged mode guarantees data transmission without an error, the acknowledged mode is appropriate for the services that have a low requirement for the real-time transmission and have a great requirement for the data accuracy. 
     The unacknowledged mode allows the receiver to know which PDU is lost during transmission since the ARQ controller  113  of the transmitter adds a PDU header including a sequence number to each PDU and transmits the PDU. Therefore, the unacknowledged mode is appropriate for the service that has requirements for the real-time transmission and the packet sequence. 
     The packet controller  115  collects various RLC control PDUs through the scheduler/control PDU collector  117  according to the data transmission mode determined by the ARQ controller  113 , and transmits the collected RLC control PDUs to a MAC layer  120  and the ARQ controller  113  by considering the resource allocation condition and using scheduler-based allocation, piggybagging, or indication bit insertion. 
     The MAC layer  120  receives an RLC data PDU from the ARQ controller  113 , receives an RLC control PDU from the packet controller  115 , multiplexes them to configure a transport block (TB)  300  that is appropriate for the radio channel, and transmits the transport block to the physical layer  130 . 
     Here, the TB  300  is configured to provide the hybrid ARQ (HARQ) and multi-input multi-output (MIMO) of the physical layer. 
       FIG. 2  is a flowchart for a data transmission method by an ARQ controller according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 2 , the ARQ controller ( 113  of  FIG. 1 ) determines the data transmission mode according to the QoS of the SDU stored in the buffer (S 110 ), and determines the transmission amount of the service packets according to the determined data transmission mode (S 120 ). 
     The ARQ controller  113  fragmentizes and concatenates the SDU depending on the data transmission amount determined by a scheduler according to the data transmission method, and generates a fragmentation block (FB) (S 130 ). 
     The ARQ controller  113  generates a PDU including the generated FB and information on the FB (S 140 ), and adds radio link control information including a PDU retransmission method and the number of fragmentation blocks included in the PDU to the generated PDU to thus generate an RLC data PDU. 
     The ARQ controller  113  transmits the generated RLC data PDU to the MAC layer (S 150 ). 
       FIG. 3  is a configuration of a TB of a MAC layer and a header field of the TB according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 3 , the TB  300  that is transmitted from the MAC layer  120  to the physical layer  130  includes a MAC header field and a payload field, and the payload field includes at least one RLC PDU  320 . Here, each RLC PDU  320  is an RLC control PDU or an RLC data PDU. 
     The MAC header field  310  includes one number field  311  and at least one size field  313 , and the number field  311  indicates the number of RLC PDUs  320  included by the TB  300 , and the at least one size field  313  indicates the size of the at least one RLC PDU  320  included by the TB  300 . 
     Here, the TB  300  may not have the MAC header field  310 . 
       FIG. 4  and  FIG. 5  show a first type and a second type of RLC PDU of a payload field of a TB according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 4 , the first type of RLC PDU  320  includes an RLC header field and an RLC payload field, the RLC header field includes an RLC information field  321  and an FB information field  323 , and the RLC payload field includes at least one FB  325 . The FB information field  323  includes information on each of the FBs  325  included by the RLC payload field. 
     As shown in  FIG. 5 , the second type of RLC PDU  320  includes an RLC information field  321 , at least one FB information field  323 , and at least one FB  325  corresponding to at least one FB information field  323 . The FB information field  323  of the second type of RLC PDU field  320  includes information on the FB  325  provided next to the FB information field  323 . 
       FIG. 6  shows an RLC information field of an RLC PDU of a TB according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 6 , the RLC information field  321  includes a type field  321   a , a link identifier field  321   b , and a sequence number field  321   c , and further includes a piggybagging indicator field  321   d , an end of buffer (EOB) indicator field  321   e , and an FB number field  321   f.    
     The type field  321   a  displays the type of RLC PDU, and includes information for processing to the packet controller, the ARQ, or other layers. Also, the type field  321   a  displays whether the RLC PDU  320  is a data PDU or a control PDU. 
     The link identifier field  321   b  identifies the link to which the RLC PDU  320  belongs in the case of requesting to retransmit the RLC PDU  320 , and is an identifier of the corresponding link for operating the ARQ. 
     The sequence number field  321   c  indicates a sequence number that is allocated for the ARQ operation to the FB  325 . 
     The piggybagging indicator field  321   d  indicates that a control PDU is included in the TB  325  in the piggybagging format so as to increase the data transmission efficiency according to the determination of the MAC layer. 
     The EOB indicator field  321   e  notifies that the buffer has no more SDU to be transmitted to the lower layer from the upper layer. 
     The FB number field  321   f  indicates the entire number of FBs included in the RLC PDU  320  when the number of FBs included in the RLC PDU  320  is plural. The information of the RLC information field  321  can limit the number of bits in consideration of byte-based operation in the realized structure of a high data rate system. For example, the type field  321   a  is configured to have 3 bits, the link identifier field  321   b  is configured to have 4 bits, the piggybagging indicator field  321   d  is configured to have 1 bit, the sequence number field  321   c  is configured to have 11 bits, the EOB indicator field  321   e  is configured to have 1 bit, and the FB number field  321   f  is configured to have 4 bits. 
       FIG. 7  and  FIG. 8  show a first type and a second type of FB information fields of an RLC PDU of a TB according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 7 , the first type of FB information field  323  includes a fragmentation control (FC) field  323   a , a starting pointer (SP) field  323   b , and an ending pointer (EP) field  323   c , and further includes an extension indicator (E) field  323   d.    
     The FC field  323   a  includes fragmentation information on the SDU of a first part, a middle part, and a last part included in the FB, and other control information. 
     The SP field  323   b  indicates starting pointer information on the FB included in the RLC PDU  320 , and the EP field  323   c  indicates the ending pointer of the FB included in the RLC PDU  320 . 
     The E field  323   d  is an indicator for notifying an existence of an additional FB when the RLC PDU  320  has the additional FB. 
     As shown in  FIG. 8 , when one FB includes an SDU that is not fragmentized, the type 2 FB information field  323  includes a length field  323   e  and further includes an E field  323   d.    
     Here, the length field  323   c  indicates the length of the FB, that is, the length of the SDU, and the E field  323   d  is an indicator of existence of an additional FB when the RLC PDU  320  has an additional FB. 
       FIG. 9  shows a configuration of an RLC control PDU according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 9 , the RLC control PDU  320  includes an RLC information field  327  and a message field  329 . 
     The RLC information field  327  includes a type field  327   a  and a message identifier field  327   b , and may further include a link identifier field  327   c.    
     The type field  327   a  indicates the type of the RLC control PDU  320 , and includes information on processing for the packet controller, the ARQ controller, or other layers. Here, the type field  327   a  can indicate whether the RLC PDU  320  is an RLC data PDU or an RLC control PDU. 
     The message identifier field  327   b  includes a transmitting object and a receiving object of the RLC control PDU  320 . 
     The link identifier field  327   c  is an identifier for identifying the link to which the RLC PDU  320  belongs in the case of requesting the receiver to retransmit the RLC PDU  320 , and is an identifier of the corresponding link for operating the ARQ. 
     The above-described embodiments can be realized through a program for realizing functions corresponding to the configuration of the embodiments or a recording medium for recording the program in addition to through the above-described device and/or method, which is easily realized by a person skilled in the art. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.