Abstract:
The present invention relates to the field of mobile communication, including method, apparatus and system for implementing IuUp/NBUP procedure control. The method includes parsing a received UP frame; generating a control message based on a value obtained from the parsing, and buffering the control message; executing the buffered control message. When multiple time alignment or rate control messages are received, the dropping or suspending of the later received messages due to the execution of a control message may be avoided; by way of setting the state of the message and adding a message identification, the successive rate adjustment procedure may be optimized. The method according to an embodiment of the present invention is capable of originating a rate or time adjustment initiatively. The present invention also discloses an apparatus and system for implementing IuUp/NBUP procedure control, with a good good extensibility, which improves the response efficiency of the system.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of mobile communication, and more particularly, the present invention relates to a method for implementing procedure control of Iu Interface (an interface between a Radio Access Network and a Core Network)/Nb Interface (an interface between Media Gateways) User Plane protocol (abbreviated as IuUP/NbUP protocol). 
     BACKGROUND OF THE INVENTION 
     In a 3G mobile communication system, the software entity of UP (User Plane, a plane for transmitting user data) protocol generally exists in an MGM (Media Gateway), an RNC (Radio Network Controller) of UTRAN (UMTS Terrestrial Radio Access Network). The Iu Interface is an interface between a Radio Access Network and a Core Network, and the Nb Interface is an interface between Media Gateways. The two objects of IuUP/NbUP protocol includes: (1) transmitting UP data, guaranteeing the QoS (Quality of Service) of UP data transmission through the UP control signaling (UP initialization, rate control, time alignment and error event Indicator); (2) keeping the independence of the CN (Core Network), thus reducing the dependence of the CN on the Transfer Network Layer (TNL), e.g. RTP/UDP/IP, as far as possible. 
     An existing technical solution of IuUP/NbUP procedure control is shown in  FIG. 1 . An UP frame checking and distributing module  101  checks the UP frame number, performs CRC (Cyclic Redundancy Check) for the UP frames received by the system, and differentiates the data frames and the control frames depending on the PDUType (Pritocol data unit type) in the UP frame header. At present, only an SMpSDU (Support mode for predefined SDU size, SMpSDU) support mode is defined in the UP protocols of 3G standard (3GPP TS 25.415, 3GPP TS 29.415). Under the SMpSDU support mode, the PDUType value of a data frame is 0 or 1, while the PDUType value of a control frame is 14. The UP frame checking and distributing module  101  determines whether a received UP frame is a control frame or a data frame according to the PDUType value of this UP frame. If it is a control frame, the UP frame checking and distributing module  101  transmits it to an UP request-frame distributing/response-frame packaging and transmitting module  102 , and if it is a data frame, the UP frame checking and distributing module  101  transmits it to a data frame processing module  108 . 
     On receiving the control frame, the UP request-frame distributing/response-frame packaging and transmitting module  102  determines the type of the control frame depending on the Procedure Indicator in the frame header, and distributes the control frame to the corresponding procedure control module according to the type of the control frame. The procedure control module may be an UP initialization processing module  103 , an UP time alignment processing module  104 , an UP rate control processing module  105  and an UP error event processing module  106 . The processing procedure of each module will be described hereinafter. On receiving the control frame, if the UP request-frame distributing/response-frame packaging and transmitting module  102  determines the control frame is an initialization frame, the UP request-frame distributing/response-frame packaging and transmitting module  102  transmits it to the UP initialization processing module  103 . If the control frame is determined to be a rate control request frame, the UP request-frame distributing/response-frame packaging and transmitting module  102  transmits it to the UP rate control processing module  105 . If the control frame is determined to be a time alignment request frame, the UP request-frame distributing/response-frame packaging and transmitting module  102  transmits it to the UP time alignment processing module  104 . The processing procedure of the modules will be described below. 
     On receiving the initialization frame, the UP initialization processing module  103  extracts a set of RFCIs (RFCI: Radio Access Bearer Sub-flow Combination Indicators) supported by the sender and the length of the bearer sub-flow service data unit (SDU) corresponding to each set of RFCIs. Thereafter, according to the set of RFCIs, the data stream processing entity will be controlled to transmit and receive the UP data streams. 
     On receiving the rate control request frame of a control originator, the UP rate control processing module  105  extracts the maximal rate demanded by the control originator, and then transmits the rate control message to the TC encoding/decoding channel, indicating the TC encoding/decoding channel to adjust the transmitting rate of the data frame to a predefined value. After a successful rate adjustment, the UP rate control processing module transmits a response frame to the control originator. 
     On receiving the time alignment request frame from the control originator, the UP time alignment processing module  104  extracts the time alignment value, and then transmits a time control message to the TC encoding/decoding channel, indicating the TC encoding/decoding channel to advance or postpone the transmitting time of the data frame by the predefined value. After a successful time alignment, the UP time alignment processing module transmits a response frame to the control originator. 
     When an error is found in the procedure for processing the data frame or the control frame, the UP error event processing module  108  will be informed. Upon the determination of the type of the error, the UP error event processing module  108  transmits an error event frame to the entity of the opposite end. As for the error event frame transmitted from the opposite end, the local end will record the event and inform the data-stream processing function entity to handle accordingly. 
     It can be seen from the above described technical solution of IUUP/NBUP procedure control that, during the procedure control, the operation of the execution entity of procedure control function, i.e. the TC encoding/decoding channel  107 , by the processing modules is asynchronous and monopolized. That is, the next operation request can not be executed before the previous operation request is ended. For example, on receiving a rate control request frame, the UP rate control processing module  105  transmits a rate control message to the TC encoding/decoding channel  107 , and the system also receives a time alignment request frame before the TC encoding/decoding channel  107  returns a response. Then the latter time alignment request will be suspended for the TC encoding/decoding channel  107  is processing the previous rate control request. According to the UP protocol of 3G standard (3GPP TS 25.415), in an UP support mode session, UP initialization is the first UP procedure control function, after which, the UP rate control processing module, the UP time alignment processing module and the UP error event processing module are all independent from each other, and cannot be restricted by each other when implementing the procedure control function. 
     For the processing of multiple successive rate control requests, according to the UP protocols of 3G standard, when the system receives multiple rate control request frames successively, the final rate control will be adopted. Thus, in this solution, only the first rate request will be processed normally, the next rate control request may be dropped. As a result, it is possible that the frame number in the response frame received by the rate control sender does not match with the frame number in the finally transmitted rate control frame, resulting in the failure of the final rate control. 
     This solution can process only the procedure control after the receipt of an UP control request, it does not support the origination of UP initialization, UP time alignment and UP rate control. According to the UP protocols of 3G standard, both of a RNC and a NGW may be not only an originator but also a handler of the UP control operations. When the RNC and MGW are the handlers of the UP control operation, it is impossible to implement the UP procedure control. 
     This solution supports only the procedure control processing under SMpSDU support mode. As the UP checking and distributing module does not differentiate the support modes when the UP frames are received, It is necessary to modify the software considerately when two versions of UP support modes need to be supported simultaneously. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method, apparatus and system for implementing IuUP/NbUP procedure control function. The method according to an embodiment of the present invention includes: 
     parsing a received UP frame; generating a control message based on a value obtained from the parsing, and buffering the control message; and executing the buffered control message. 
     According to the embodiments of the present invention, a method for implementing IuUP/NbUP procedure control includes: 
     parsing a received rate control request frame; generating a rate control message based on a rate value obtained from the parsing, and buffering the rate control message; adjusting a rate by use of the buffered rate control message. 
     According to the embodiments of the present invention, a method for implementing IuUP/NbUP procedure control includes: 
     sending, by a first system, an UP frame to a second system when the first system gets an origination command; 
     parsing, by the second system, the received UP frame, generating a control message based on a value obtained from the parsing, and buffering the control message, executing the buffered control message, and returning a response frame to the first system after executing the control message. 
     According to the embodiments of the present invention, an apparatus for implementing IuUP/NbUP procedure control includes: 
     an UP rate control request processing module or an UP time alignment request processing module for parsing a received UP frame and generating a control message based on a value obtained from the parsing and buffering the control message into a message queue processing module; 
     the message queue processing module for buffering the control message and sending the control message to a procedure control execution module; 
     the procedure control execution module for executing the buffered control message. 
     According to the embodiments of the present invention, an apparatus for implementing IuUP/NbUP procedure control includes: 
     an UP rate control request processing module for parsing a received rate control request frame and generating a rate control message based on a rate value obtained from the parsing and buffering the rate control message into a message queue processing module; 
     the message queue processing module for buffering the rate control message and sending the rate control message to a procedure control execution module; 
     the procedure control execution module for adjusting a rate by use of the buffered rate control message. 
     According to the embodiments of the present invention, a system for implementing IuUP/NbUP procedure control includes: 
     an UP initialization origination processing module, an UP time alignment origination processing module and an UP rate control origination processing module in a first system, for send an UP frame to a second system when the first system gets an origination command; 
     an IuUP/NBUP procedure control device in the second system for parsing the received UP frame, generating a control message based on a value obtained from the parsing, and buffering the control message, executing the buffered control message, and returning a response frame to the first system after executing the control message. 
     It can be seen that: (1) the method and system of the present invention possess relatively good extensibility because the coexistence of multiple UP support modes has been taken into account and the software architecture does not need a significant modification; (2) by way of buffering multiple UP frames on receiving multiple UP frames, it can be ensured that all the procedure modules are kept independent with each other and are not restricted by each other, which solves the problem of being suspended by each other; (3) the origination operation and processing operation of UP procedure control may be supported simultaneously; (4) the repeated and successive rate control requests may be handled properly, and optimization may be implemented when the rate controls are originated successively, thus reducing the number of unnecessary rate control frames between the devices and avoiding repeated rate adjustment when the requirements of rate control are the same. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural diagram illustrating the IuUP/NbUP procedure control function according to the prior art; 
         FIG. 2  is a structural diagram illustrating the IuUP/NbUP procedure control function according to an embodiment of the present invention; 
         FIG. 3  is a flow chart for processing a rate control request frame according to an embodiment of the present invention; 
         FIG. 4  is a flow chart illustrating the TC encoding/decoding channel returning the rate control response message according to an embodiment of the present invention; 
         FIG. 5  is a flow chart illustrating the TC encoding/decoding channel originating a rate adjustment request control message according to an embodiment of the present invention; 
         FIG. 6  is a flow chart illustrating process on the reception of the rate control response frame according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIG. 2 , a system for implementing IuUP/NbUP procedure control function includes an UP request-frame distributing/response-frame packaging and transmitting module  12  under Support mode for predefined Service Data Unit size (SMpSDU), an UP data frame processing module  11 , an UP initialization request processing module  14 , an UP time alignment request processing module  15 , an UP rate control request processing module  16 , an UP error event processing module  17  and a TC encoding/decoding channel  21 . Wherein, the control message is executed by the procedure control execution module in the embodiment of the present invention, the procedure control execution module may be implemented in a variety of manners. In an embodiment of the present invention, the procedure control execution module is the TC encoding/decoding channel  21 . 
     The System May Also Include: 
     A message queue processing module  22 , for buffering the control messages from the UP time alignment request processing module and the UP rate control request processing module; 
     An UP support mode determining module  8  for determining the support mode of an UP frame; 
     A predefined support mode processing module  10  for processing an UP frame of a predefined support mode; 
     An UP frame checking and determining module  9  for determining whether a received UP frame is a request frame or a response frame; 
     An UP initialization origination processing module  18  for processing an initialization operation originated by control plane signaling; 
     An UP time alignment origination processing module  19  for processing a time alignment control operation originated by the procedure control function executing entity; 
     An UP rate control origination processing module  20  for processing a rate adjustment control operation originated by the procedure control function executing entity; 
     An UP request-frame packaging and transmitting/response-frame distributing module  13  for distributing a response frame to the UP initialization origination processing module  18 , the UP time alignment origination processing module  19  or the UP rate control origination processing module  20  based on the type of the response frame, and packaging and transmitting a request frame originated by the procedure control function executing entity. 
     A preferred embodiment of the present invention is given below. As shown in  FIG. 2 , when the system receives an UP frame, the UP support mode determining module  8  determines the type of the UP support mode based on the PDUType value in the UP frame header first. At present, the UP protocols of 3G standard defines only the SMpSDU support mode, but different manufacturers may have different support modes. Each support modes corresponds to a module for processing that UP support mode. The support modes is determined, the UP frame may be processed by the corresponding processing module. 
     If it is determine that the support mode is not SMpSDU, the UP frame may be sent to the predefined support mode processing module  10 . If it is determine that the support mode is SMpSDU, the UP frame may be sent to the UP frame checking and determining module  9 . The UP frame checking and determining module further checks the frame number of the UP frame, performs the CRC check and determines the type of the UP frame according to the value of PDUType of the UP frame. If the value of PDUType is 0 and 1, the UP frame is a date frame, and will be sent to the data frame processing module  11 . If the value of PDUType is 14, the UP frame is a control frame; then it may be determined whether the UP frame is a request frame or a response frame based on the Ack/Nack field in the frame header (Please refer to 3GPP TS 25.415 for the specific UP control frame structure). If the UP frame is a request frame, it will be distributed to the UP request-frame distributing/response-frame packaging and transmitting module  12 ; otherwise, it will be distributed to the UP request-frame packaging and transmitting/response-frame distributing module  13 . 
     On receiving a request frame, the UP request-frame distributing/response-frame packaging and transmitting module  12  determines the control type of the request frame based on the Procedure Indicator field in the frame header, then distributes the request frame to the UP initialization request processing module  14  if it is determined that the request frame is an initialization frame, to the UP time alignment request processing module  15  if it is determined that the request frame is a time alignment request frame, to the UP rate control request processing module  16  and the UP error event processing module  17  if it is determined that the request frame is a rate control request frame. 
     On receiving a response frame, the UP request-frame packaging and transmitting/response-frame distributing module  13  determines the control type of the response frame based on the Procedure Indicator field in the frame header, and then distributes the response frame to the UP initialization origination processing module  18 , the UP time alignment origination processing module  19  or the UP rate control origination processing module  20  according to the type of the response frame. Upon the triggering of the control plane signaling from a third party or the triggering of the encoding/decoding channel of the local end, the UP initialization origination processing module  18 , the UP time alignment origination processing module  19  and the UP rate control origination processing module  20  will transmit control messages to the UP request-frame packaging and transmitting/response-frame distributing module  13 , and the control messages will be packaged into the corresponding request frames uniformly and the request frames will be transmitted to the UP protocol entity of the opposite end. 
     The individual modules for processing the request frame will be described below. 
     An operation control block is set in each of the UP initialization request processing module  14 , the UP time alignment request processing module  15 , the UP rate control request processing module  16  and the UP error event processing module  17  for saving the information such as the frame number of the request frame, the operation state and the like. When these request processing modules transmit a response frame to an entity of the opposite end, the frame number of the corresponding request frame will be filled back in the response frame, which can ensure the control originator to match the request frame and the response frame properly. 
     On receiving an initialization frame, the UP initialization request processing module  14  will extract a set of RFCIs (including the bearer sub-flow SDU size corresponding to each RFCI in the set of RFCIs) supported by the control originator, and thereafter will control the UP dada frame processing module  11  according to the set of RFCIs to transmit and receive the UP data streams. 
     On receiving a time alignment request frame of the control originator, the UP time alignment request processing module  15  will extract the time alignment value, and transmit a time control message to the TC encoding/decoding channel  21 , indicating the TC encoding/decoding channel  21  to advance or postpone the transmitting time of the UP data frame processing module  11  by an designated value of time. The time control message is buffered in a FIFO (First In First Out) message queue processing module  22  before being transmitted to the TC encoding/decoding channel  21 , and the message queue processing module  22  extracts the queue-header message and transmits it to the TC encoding/decoding channel  21 . If the operation of TC encoding/decoding channel  21  is time-out, the queue-header message will be deleted and the next time control message in the queue will be processed. If a response message from the TC encoding/decoding channel  21  is received, the queue-header message will be deleted from the queue, and the response message of successful time alignment will be returned to the UP time alignment request processing module  15 , and will be transmitted to the control originator by the UP time alignment request processing module  15 . 
     On receiving a rate control request frame from the control originator, the UP rate control request processing module  16  will extract the maximal rate that the control originator demands, and transmit a rate control message to the TC encoding/decoding channel  21 , indicating the TC encoding/decoding channel  21  to adjust the transmitting rate of the UP data frame processing module  11  to the designated value. Similarly the rate control message needs to be buffered in the FIFO message queue processing module  22  before being transmitted to the TC encoding/decoding channel  21 . The message queue processing module  22  extracts the queue-header message and transmits it to the TC encoding/decoding channel  21 . If the operation of TC encoding/decoding channel  21  is time-out, the queue-header message will be deleted and the next rate control message in the queue will be processed. When the response message from the TC encoding/decoding channel  21  is received, the queue-header message will be deleted from the queue, and the response message of successful rate control will be returned to the UP rate control request processing module  16 , and will be transmitted to the control originator by the UP rate control request processing module  16 . 
     The time control message and the rate control message transmitted from the UP time alignment request processing module  15  and the UP rate control request processing module  16  to the TC encoding/decoding channel  21  may share the same message queue processing module  22 , or may use the separate message queue processing modules in their corresponding request processing modules. When sharing the same message queue processing module  22 , the same message queue processing module  22  will process the control messages in a FIFO sequence, which ensures that one control operation will not be forced to be suspended or dropped due to the execution of the other control operations. When employing the separate message queues in their corresponding request processing modules, the system needs to check the states of the other request operations when it executes one control request operation. If the other operations are being executed, the current operation will be buffered in its message queue and will be executed when the other processing modules become idle. 
     Similarly, the UP time alignment request processing module  15  and the UP rate control request processing module  16  may share one execution entity, e.g., TC encoding/decoding channel  21 , to execute the control request operations. Alternatively, the processing modules related with data-stream processing can be used as execution entities of different control request operations. For example, the TC encoding/decoding channel  21  can be used for executing rate adjustment operation, and the UP data-frame processing module  11  can be used for executing time alignment operation. 
     Hereinafter the procedure that the UP rate control request processing module  16  processes the rate control request frames will be further described. As shown in  FIG. 3 , the operation control block of the UP rate control request processing module  16  only saves the information of the latest rate control request including the rate, operation state (Waiting or Termination), frame number of the request frame. On receiving the rate control request frame from the control originator (step S 10 ), firstly, it checks whether the latest operation state buffered in its operation control block is Waiting or Termination (step S 11 ). 
     If the state is Termination, it judges whether the rate of this rate control request is equal to the currently buffered rate (step S 12 ), and if yes, an ACK Frame will be directly returned to the control originator (step S 13 ), that is, a success response will be directly replied to the control originator, thereby avoiding meaningless control operations to the TC encoding/decoding channel and hence improving the response efficiency of the system. If the rate of this rate control request is not equal to the currently buffered rate, the information of the rate control request frame will be buffered in the operation control block and an MsgID will be generated (step S 14 ), then a waiting timer is started, and a rate control message is transmitted to the message queue processing module  22  with the message ID=MsgID, and the state of its operation control block is set as Waiting (step S 15 ). Then the message queue processing module  22  transmits the rate control message to the TC encoding/decoding channel (step S 16 ). The TC encoding/decoding channel executes the rate control request operation (step S 17 ). 
     If the state is Waiting, it is also necessary to determine whether the rate of this rate control request is equal to the currently buffered rate (step S 18 ), and if yes, the frame number of the request frame in the operation control block is updated as the frame number of the current rate control request frame (step S 19 ); and if not, the information of the rate control request frame is buffered in the operation control block and a new MsgID is generated (step S 20 ). Then the waiting timer is stopped first, and is restarted again, and this rate control message is sent to the message queue processing module  22  with the message ID=MsgID (step S 21 ). Then the message queue processing module  22  transmits the rate control message to the TC encoding/decoding channel  21  (step S 22 ), and the TC encoding/decoding channel  21  executes the rate control operation (step S 23 ). The procedure of the TC encoding/decoding channel  21  returning a rate control response message and the procedure of the processing of the UP rate control request processing module  16  will be described below. 
     As shown in  FIG. 4 , when the TC encoding/decoding channel  21  returns the previous rate control response message to the message queue processing module  22 , the message queue processing module  22  will return the rate control response message to the operation control block of the UP rate control request processing module  16  and delete the queue-header message (step S 30 ). 
     On receiving the rate control response message, the UP rate control request processing module  16  judges whether the state of its operation control block is Waiting, and whether the MsgID of this response message matches with that saved in the operation control block (step S 31 ). If the state is Waiting and it matches, the waiting timer is stopped, and the state of the operation control block is set as Termination (step S 22 ). Then it is determined, by use of the rate control response message, whether the operation of the TC encoding/decoding channel is successful (step S 33 ), and if yes, a rate control Ack Frame is constructed and transmitted, in which the frame number of the AcK frame is that saved in the operation control block (step  34 ). If it is not successful, a rate control Nack Frame is constructed and transmitted, in which the frame number of the NacK frame is that saved in the operation control block (step S 35 ). If the state is not Waiting or it does not match, the rate control response frame is dropped, which is recorded in log (step S 36 ). In this way, the MsgID will not be matched until the TC encoding/decoding channel  21  returns the last rate control response frame. At this time, the UP rate control request processing module  16  returns a response frame to the control originator according to the frame number of the latest rate control request frame, thus ensuring the properness of the successive rate control processing, so that the later rate control request frame will not be answered until the earlier rate control request frames are dropped. 
     If an error is found when processing the UP data frame or the UP control frame, the UP error event processing module  17  will be informed. After determining the error type, the UP error event processing module  17  will transmit an error event frame to the entity of the opposite end. As for the error event frame transmitted from the opposite end, the local end will record the event and inform the data-stream processing function entity to handle accordingly. 
     As can be seen from  FIG. 2  that the present invention also supports the control origination of the UP control operation. UP initialization is driven by the control plane signaling, and in general, UP initialization is originated when the call establishes a link. Rate control and time alignment are control operations originated by the UP data frame processing module  11  according to the requirements for processing the UP Data-streams, or may be originated by the TC encoding/decoding channel. When a TFO (Tandem Free Operation) connection is established between a 3G MGW and a GSM central office, the core network will originate rate control to the RAN (Radio Access Network), which is generally undertaken by the TC encoding/decoding channel  21  on MGW during the TFO negotiation. Hereinafter an example of the TC encoding/decoding channel  21  originating a control operation will be described. 
     An origination operation control block is set in each of the UP initialization origination processing module  18 , the UP time alignment origination processing module  19  and the UP rate control origination processing module  20  for saving the information such as a duplicate of a transmitting frame, operation state and the retransmission counter. If the entity of the opposite end has no response, the entity of the local end will retransmit the buffered duplicate of the control frame and begin to count. When the count exceeds a designated number of times (e.g. it can be set 3 times by the system), the current operation will be terminated. The operation state is Waiting when waiting for the response frame, while the operation state is Idle when the response frame of the opposite end is received or retransmission times exceeds the designated number of times. 
     As shown in  FIG. 5 , after the TC encoding/decoding channel  21  transmits a rate adjustment request message to the UP rate control origination processing module  20  (step S 40 ). The UP rate control origination processing module  20  checks the state of the origination operation saved in its origination operation control block firstly (step S 41 ). If the state is Idle, the UP rate control origination processing module  20  constructs and buffer the rate control request frame (step S 42 ), and the waiting timer is started, the transmission counter is increased by 1 and the state of the origination operation is set as Waiting (step S 43 ), then the rate control request frame is transmitted (step S 44 ). If the state of the origination operation is Waiting, the UP rate control origination processing module  20  judges whether the request adjustment rate required by the TC encoding/decoding channel  21  is equal to the request adjustment rate buffered in its origination operation control block (step S 45 ), and if yes, the rate adjustment request message of the TC encoding/decoding channel  21  will be dropped (step S 46 ); and if not, the waiting timer is stopped, the retransmission counter is reset to 0, the operation state is set as Idle, the memory for buffering the rate control request frame is released, which is recorded in log (step S 47 ). Then the process returned to step S 42 , the rate control request frame is constructed and buffered again (step S 42 ), the waiting timer is restarted, and the retransmission counter is reset to 1 (step S 43 ), the rate control request frame is retransmitted (step S 44 ). 
     Then as shown in  FIG. 6 , on receiving the earliest rate control response frame (step S 50 ), firstly, the UP rate control origination processing module  20  checks whether the frame number matches with the frame number saved in the origination operation control block, and whether the operation state is Waiting (step S 51 ). If the frame number does not match or the operation state is not Waiting, the rate control response frame will be dropped, which is recorded in log (step S 52 ). If the frame number matches and the operation state is Waiting, the waiting timer will be stopped, the state of the origination operation control block will be set as Idle, the retransmission counter will be set to 0, and the memory for buffering the rate control request frame will be released (step S 53 ). Then the UP rate control origination processing module  20  determines whether the entity of the opposite end is successful according to the response frame (step S 54 ), and if yes, the UP rate control origination processing module  20  constructs a rate control ACK Frame and transmits it to the TC encoding/decoding channel  21  (step S 55 ); otherwise, the UP rate control origination processing module  20  constructs a rate control Nack Frame and transmits it to the TC encoding/decoding channel  21  (step S 56 ).