JP2007288746A - Communication terminal, and data transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably transmit SDUs even if troubles caused by wireless errors occur in PDU transmission. <P>SOLUTION: A wireless communication terminal 10 has an RLC layer 120 which receives transmission target SDUs from upper layers and generates one or more PDUs based on the SDUs to output them to lower layers. In addition, the wireless communication terminal 10 also has a lower layer (mainly, a layer 1) which detects that troubles occur in transmission before completion of transmitting all generated PDUs, and an upper layer (mainly, a layer 3) which instructs link re-establishment as a trigger of SDU retransmission to the RLC layer 120 if a trouble occurrence is detected. The RLC layer 120 has a storage 121 which stores transmission target SDUs received from upper layers, and a regeneration 122 which regenerates PDUs based on the stored SDUs to output them to lower layers if link re-establishment is instructed from an upper layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication terminal and a data transmission method in the communication terminal.

In a mobile communication system such as a W-CDMA (Wideband-Code Division Multiple Access) system, the protocol configuration of the radio interface of the radio communication terminal is layer 1 (physical layer), layer 2 (data link layer), and layer 3 (network layer). ) 3 layers. In packet transmission at a wireless communication terminal in the W-CDMA system, a PDU (Protocol Data Unit) is generated from an SDU (Service Data Unit) in Layer 2 and transmitted based on a transmission request from Layer 3 ( For example, see Patent Document 1 below).
JP 2004-179917 A

  When a plurality of PDUs generated by layer 2 are being transmitted, if a radio abnormality occurs between the wireless communication terminal and the network, retransmission of retransmissions, or the like, the PDU cannot be transmitted. Thereafter, layer 3, which is an upper layer, instructs layer 2 to re-establish the link. However, normally, when the link reestablishment at layer 2 is performed, the SDUs and PDUs to be transmitted held at layer 2 are deleted, so that the SDUs to be transmitted are transmitted as a result. Not.

  The present invention has been made to solve the above problems, and provides a communication terminal and a data transmission method capable of reliably transmitting an SDU even if a PDU transmission failure occurs due to a radio abnormality or the like. The purpose is to provide.

  In order to achieve the above object, a communication terminal according to the present invention receives a transmission target SDU from an upper layer, generates one or more PDUs from the SDU, and outputs a PDU generation layer to the lower layer. A communication terminal comprising: a detecting means for detecting that a failure has occurred in transmission before transmission of all generated PDUs is completed; and a PDU generation layer when a failure has been detected by the detecting means And an instruction unit for instructing the retransmission of the SDU, and the PDU generation layer holds the holding unit for holding the SDU to be transmitted received from the higher layer, and holds the instruction when the instruction unit instructs the retransmission of the SDU. Regenerating means for regenerating a PDU from the SDU held by the means and outputting it to a lower layer.

  In the communication terminal according to the present invention, the SDU to be transmitted is held in the PDU generation layer, and if a failure occurs before transmission of all the PDUs generated from the SDU is completed, the PDU is stored from the held SDU. Regenerate. Therefore, according to the communication terminal according to the present invention, even if a failure occurs in PDU transmission, the regenerated PDU is transmitted, so that the SDU can be transmitted reliably.

  The communication terminal is based on the W-CDMA system, and the PDU generation layer is preferably a layer 2 layer. According to this configuration, the present invention can be easily and reliably implemented in a communication terminal using the W-CDMA system.

  By the way, the present invention can be described as an invention of a communication terminal as described above, and can also be described as an invention of a data transmission method in the communication terminal as follows. This is substantially the same invention only in different categories, and has the same operations and effects.

  That is, in the data transmission method according to the present invention, data in a communication terminal including a PDU generation layer that receives an SDU to be transmitted from an upper layer, generates one or more PDUs from the SDU, and outputs the PDU to a lower layer. A detection method for detecting that a transmission failure has occurred before transmission of all generated PDUs is completed, and when a failure has been detected in the detection step, the PDU generation layer An instruction step for instructing retransmission of the SDU, and when the PDU generation layer is instructed to retransmit the SDU in the holding step for holding the SDU to be transmitted received from the higher layer, and in the instruction step, A regeneration step of regenerating a PDU from the held SDU and outputting it to a lower layer. To.

  According to the present invention, if a failure occurs before the transmission of all PDUs is completed, the PDU is regenerated from the held SDU. Therefore, even if a failure occurs in the transmission of the PDU, the regenerated PDU is transmitted. Therefore, SDU can be transmitted reliably.

  Hereinafter, preferred embodiments of a communication terminal and a data transmission method according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 shows a configuration of a wireless communication terminal (communication terminal) 10 according to the present embodiment. In the present embodiment, the wireless communication terminal 10 is capable of mobile communication using the W-CDMA method.

  FIG. 2 shows a hardware configuration of the wireless communication terminal 10. As shown in FIG. 2, a wireless communication terminal 10 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, a ROM (Read Only Memory) 103, an operation unit 104, a wireless communication unit 105, a display 106, and an antenna. It is configured by hardware such as 107. When these components operate, the functions of the wireless communication terminal 10 described below are exhibited.

  The configuration of the wireless communication terminal 10 shown in FIG. 1 shows a layer configuration in a wireless communication protocol. As shown in FIG. 1, the wireless communication terminal 10 includes a layer 1 (11), a layer 2 (12), a layer 3 (13), a TAF 14, and an application 15.

  Layer 1 (11) performs data transmission / reception by physical wireless communication, reception level measurement, synchronization detection, and the like. Specifically, the layer 1 (11) has a physical layer, and the physical layer has the above function. The layer 1 (11) transmits the PDU output from the higher layer (layer 2 (12)), that is, transmits the PDU to the network (mobile communication network). The layer 1 (11) is also a detection unit that detects that a transmission failure has occurred before the transmission of all the PDUs transferred from the higher layer is completed. Specifically, this detection is performed by synchronization detection or the like. When layer 1 (11) detects the occurrence of a failure in transmission as described above, layer 1 (11) notifies layer 3 (13) to that effect.

  Layer 2 (12) is a higher layer than layer 1 (11), and performs transmission on a logical channel. Specifically, the layer 2 (12) includes an RLC (Radio Link Control) layer 120 as shown in FIG. The RLC layer 120 is a PDU generation layer that generates one or more PDUs that are packetized data from SDUs that are transmission target data received from an upper layer. Here, the SDU includes both a control (RRC: Radio Resource Control) message and user data. In addition, the RLC layer 120 receives PDUs as received data from lower layers, assembles SDUs from the PDUs, and passes them to higher layers.

  The RLC layer 120 includes a holding unit 121 (holding unit) that holds SDUs that are transmission target data received from an upper layer. Specifically, the SDU is held by storing the SDU in a memory that can be accessed by the RLC layer 120. In addition, when the RLC layer 120 is instructed to reestablish the link (connection at the layer 2 (12) level) by an upper layer, the RLC layer 120 receives the PDU from the SDU that holds the reestablishment instruction as a trigger for retransmission of the SDU. A regeneration unit 122 (regeneration unit) that regenerates and outputs to a lower layer is included. The PDU regeneration is performed in the same manner as the first PDU generation. However, when all the PDUs to be transmitted are output to the lower layer before the reestablishment instruction, the RLC layer 120 does not determine that it is an SDU retransmission instruction and does not regenerate the PDU. . It should be noted that functions other than the holding unit 121 and the regeneration unit 122 in the RLC layer 120 are not shown as functional blocks in FIG. The above PDU generation and regeneration processing will be described in more detail later.

  The layer 2 (12) has a MAC (Medium Access Control) layer (not shown). The MAC layer is located between the RLC layer 120 and the layer 1 (11), and performs mapping and concealment processing of PDUs received from higher layers to each channel.

  Layer 3 (13) is an upper layer of layer 2 (12), and performs radio resource control, call control, mobility management, and the like. Further, the layer 3 (13) passes the SDU to be transmitted to the RLC layer 120 based on an instruction from the higher layer. In addition, when the layer 3 (13) receives a notification from the layer 1 (11) that the transmission has failed before the transmission of all PDUs is completed, the layer 3 (13) instructs the RLC layer 120 to establish a link. Since the link establishment instruction triggers SDU retransmission in the RLC layer 120, the layer 3 (13) substantially detects that a failure has occurred in the layer 1 (11). It serves as an instruction means for instructing retransmission of the SDU. However, in such a configuration, it is not necessary to cause layer 3 (13) to perform special processing.

  Specifically, the layer 3 (13) includes an RRC layer, a GMM (GPRS Mobility Management) layer, an MM (Mobility Management) layer, a CC (Call Control) layer, and an SM (Session Management) layer. (All not shown). Each function of the layer 3 (13) is realized by the following functions of these components. The RRC layer is located between the RLC layer 120 and the GMM layer, MM layer, CC layer, and SM layer, and transmits and receives messages. The GMM layer is an upper layer of the RRC layer, and performs mobility management, authentication control, and the like related to packet communication and the like. The MM layer is an upper layer of the RRC layer, and performs mobility management, authentication control, and the like related to voice communication and the like. The SM layer is an upper layer of the GMM layer and performs call control such as packet communication. The CC layer is an upper layer of the MM layer and performs call control such as voice communication.

  The TAF 14 is an upper layer of the layer 3 (13), receives an instruction from the application 15, and instructs the lower layer (layer 3 (13)). The application 15 is a user interface and handles user data. As shown in FIG. 1, the application 15 is a layer higher than the TAF 14 and the layer 2 (12).

  Subsequently, processing (data transmission method) executed by the wireless communication terminal 10 of the present embodiment will be described with reference to the sequence diagram of FIG. This process is a process when data is transmitted from the wireless communication terminal 10 triggered by a user operation or the like. In the following, as illustrated in FIG. 3, the processing of the radio communication terminal 10 is performed by using the RLC layer 120, a layer higher than the RLC layer 120 (hereinafter referred to as an upper layer), and a lower layer (hereinafter referred to as the RCL layer 120). This process will be described as each process of the three configurations. The upper layer specifically corresponds mainly to layer 3 (13), and the lower layer specifically corresponds mainly to layer 1 (11).

  First, an SDU transmission request is made from the upper layer to the RLC layer 120, and the SDU is passed to the RLC layer 120 (S01). In the RLC layer 120, the SDU is held by the holding unit 121 (S02, holding step). Subsequently, in the RLC layer 120, a PDU is generated from the SDU (S03). A PDU, usually an SDU, is divided into a predetermined unit data length (in this embodiment, the packet data length), and a header including control information such as the data length is added to the PDU. When the data length of the SDU does not need to be divided, the division is not necessarily performed. This header includes a sequence number (SN) in order to specify the PDU. The sequence number is a continuous integer value. If the wireless communication terminal 10 uses up to m−1 (m is an integer) by the time the PDU is generated (this value is managed by the wireless communication terminal 10). ), The sequence number of the generated PDU is determined in order such as m, m + 1, m + 2.

  The generated PDU is output together with the transmission request from the RLC layer 120 to the lower layer (S04). Subsequently, the PDU output from the RLC layer 120 is transmitted by the lower layer (S05). Transmission is performed by sequentially transmitting PDUs from the lower layer to the network. Here, if the PDU is normally transmitted and the wireless communication terminal 10 receives an Ack corresponding to the transmission of the PDU from the transmission destination, the PDU and SDU are deleted from the RLC layer 120 and the memory is released. Note that an SDU is formed in the destination terminal from the PDU transmitted from the wireless communication terminal 10 and normally received by the destination terminal.

  In the present embodiment, it is assumed that a radio abnormality occurs between the radio communication terminal 10 and the network during the sequential transmission of PDUs. The radio abnormality occurs, for example, because the radio communication terminal 10 goes out of the communication area of the mobile communication system, and disables communication between the radio communication terminal 10 and the network. A failure also occurs in the transmission of PDUs due to the occurrence of radio abnormality.

  If a transmission failure occurs before the transmission of all PDUs is completed, the occurrence of this failure is detected by the lower layer. This detection is performed, for example, by detecting loss of synchronization as described above. When the occurrence of a failure is detected, the lower layer notifies that fact to the upper layer (S06, detection step). Subsequently, the upper layer notified of the occurrence of the failure gives an instruction to re-establish the link to the RLC layer 120 (S07, instruction step).

  Also in the conventional wireless communication terminal, when the occurrence of a failure is detected in the lower layer, this is notified to the upper layer and an instruction to re-establish the link is given. However, in the conventional wireless communication terminal, when the link is re-established, the SDU and PDU are erased in the RLC layer 120, and the SDU cannot be retransmitted.

  Also in this embodiment, when a link reestablishment instruction is given from the upper layer to the RLC layer 120, the reestablishment is performed. Subsequently, in the RLC layer 120, an instruction to re-establish the link is used as a trigger for retransmission of the SDU, and the SDU held by the holding unit 121 is read by the regenerating unit 122 of the RLC layer 120, A PDU is regenerated from the SDU (S08, regeneration step). The PDU regeneration is performed in the same manner as the PDU generation in S03 described above. However, the sequence number is reset and assigned from 0. That is, as shown in FIG. 3, if three PDUs are regenerated, their sequence numbers are 0, 1, and 2, respectively. This is because the regenerated PDU is not associated with the state of the memory or the like of the wireless communication terminal 10 before regenerating, and the SDU can be reliably formed from the regenerated PDU at the transmission destination. . In the present embodiment, the reason why the PDU generated in S03 is not used for retransmission is to make it possible to clearly distinguish the PDU related to the first transmission and the PDU related to the retransmission at the transmission destination.

  Subsequently, as in S04 and S05, the PDU regenerated from the RLC layer 120 is output to the lower layer (S09), and the PDU is sequentially transmitted by the lower layer (S10). As described above, when the PDU is normally transmitted and the wireless communication terminal 10 receives an Ack corresponding to the transmission of the PDU from the transmission destination, the PDU is deleted from the RLC layer 120 and the memory is released. The SDU held by the holding unit 121 is also erased from the RLC layer 120, and the memory used to hold the SDU is released (S11).

  The above is description of the process performed with the radio | wireless communication terminal 10 of this embodiment. Next, processing performed by the wireless communication terminal 10 of this embodiment when a wireless abnormality occurs after all PDUs have been transmitted by the lower layer will be described with reference to the sequence diagram of FIG. As shown in FIG. 4, in the PDU transmission (S05), when transmission of all PDUs is completed, the occurrence of a PDU transmission failure by the lower layer is detected, and the link reestablishment from the upper layer is performed. Even if there is an instruction, PDU regeneration and transmission are not performed. In this case, the SDU held by the holding unit 121 is erased from the RLC layer 120 triggered by a link regeneration instruction from the higher layer, and the memory used to hold the SDU is released. The In the RLC layer 120, whether or not all PDUs have been transmitted is detected by, for example, notification from a lower layer.

  This is because transmission of all PDUs from the wireless communication terminal 10 is performed, so that all PDUs may be received at the transmission destination, and retransmission may be useless. Because.

  As described above, according to the present embodiment, the regenerated PDU is transmitted even if a failure occurs in the transmission of the PDU, so that the SDU can be reliably transmitted. In addition, in the W-CDMA wireless communication terminal 10 as in the present embodiment, it is easy and reliable if SDU retention and PDU regeneration are performed in the RLC layer 120 of layer 2 (12). The present invention can be implemented. In a radio system, transmission errors are likely to occur, and retransmission of PDUs in layer 2 (12) depends on the environment. Therefore, charging based on the number of PDUs in layer 2 (12) is usually not carried out very much, Even when charging is performed based on the number of received SDUs, the network side does not receive SDUs twice, so that the problem of charging due to retransmission does not occur.

  In the present embodiment, the wireless communication terminal 10 has the layer configuration shown in FIG. However, the communication terminal according to the present invention does not necessarily have the above-described layer configuration. The communication terminal receives the SDU to be transmitted from an upper layer, generates one or more PDUs from the SDU, and generates a lower layer. As long as it has a PDU generation layer to be output to.

  In this embodiment, link reestablishment from the upper layer is used as a trigger for SDU retransmission in the RLC layer 120. However, an SDU retransmission instruction may be issued from the upper layer to the RLC layer 120. .

  Further, in the present embodiment, the cause of the PDU transmission failure has been described as a wireless abnormality, but any failure other than a wireless abnormality can be detected by the wireless communication terminal 10. For example, it may be a transmission failure due to recycle out of retransmission.

It is a figure which shows the function structure of the radio | wireless communication terminal in embodiment of this invention. It is a figure which shows the hardware constitutions of the radio | wireless communication terminal in embodiment of this invention. It is a sequence diagram which shows the process (data transmission method) performed with the radio | wireless communication terminal in embodiment of this invention. It is a sequence diagram which shows the process (data transmission method) performed with the radio | wireless communication terminal in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Wireless communication terminal, 11 ... Layer 1, 12 ... Layer 2, 120 ... RLC layer, 121 ... Retention part, 122 ... Regeneration part, 13 ... Layer 3, 14 ... TAF, 15 ... Application.

Claims (3)

A communication terminal including a PDU generation layer that receives an SDU to be transmitted from an upper layer, generates one or more PDUs from the SDU, and outputs the PDU to a lower layer.
Detecting means for detecting a failure in transmission before transmission of all the generated PDUs is completed;
An instruction means for instructing the PDU generation layer to retransmit the SDU when the detection means detects that the failure has occurred;
The PDU generation layer is
Holding means for holding SDUs to be transmitted received from the upper layer;
A regenerating unit that regenerates a PDU from the SDU held by the holding unit and outputs it to a lower layer when instructed to retransmit the SDU by the instruction unit;
A communication terminal comprising: The communication terminal is based on a W-CDMA system,
The PDU generation layer is a layer 2 layer.
The communication terminal according to claim 1. A data transmission method in a communication terminal including a PDU generation layer that receives an SDU to be transmitted from an upper layer, generates one or more PDUs from the SDU, and outputs the PDU to a lower layer,
A detection step of detecting that a transmission failure has occurred before transmission of all the generated PDUs is completed;
An instruction step for instructing the PDU generation layer to retransmit the SDU when it is detected that the failure has occurred in the detection step;
The PDU generation layer is
A holding step of holding a transmission target SDU received from the higher layer;
When instructed to retransmit the SDU in the instructing step, a regenerating step of regenerating a PDU from the SDU held in the holding step and outputting the PDU to a lower layer;
A data transmission method comprising:

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