JP2006050649A - Distributed transmission apparatus with re-transmission function and method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve re-transmission of a data frame in a distributed transmission apparatus that is a transmission apparatus comprised of individual CCU and PCU units. <P>SOLUTION: The present invention relates to a distributed transmission apparatus and method thereof in a communication system wherein re-transmission of a data frame can be requested by a receiver MS. According to the present invention, a transmission unit CCU in the distributed transmission apparatus transmits a data frame to the receiver MS and the transmitted data frame is stored. Further, the apparatus also comprises a control unit PCU for transmitting the data frame to the transmission unit CCU for transmission to the receiver MS and transmitting control data to the transmission unit CCU for controlling the re-transmission of the data frame, and this control unit PCU controls the transmission unit CCU to re-transmit, to the receiver MS, the data frame stored in the transmission unit CCU. Thus, necessity of communication between the PCU and the CCU is reduced, namely, in the case of re-transmission, capacity of a secondary link is not wasted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a distributed transmission apparatus and method in a communication system that can request retransmission of a data frame.

  In communication configurations that can request retransmission when a data frame is received in error, an automatic repeat request (ARQ) protocol can be used to control retransmission. In a communication system using the ARQ protocol, a transmitter transmits a data frame to a receiver and receives a confirmation frame from the receiver. Hereinafter, the communication channel between the transmitter and the receiver is referred to as a primary link.

  The transmitter is divided into two parts: a protocol control unit (PCU) and a channel coding unit (CCU). The PCU includes an implementation of the ARQ protocol used over the primary link. The CCU includes lower layer functions such as channel coding and modulation for the primary link. The service of the CCU is used by the PCU. The PCU and CCU are located at different locations. Hereinafter, the communication channel between the PCU and the CCU is referred to as a secondary link.

  This type of situation is, for example, in a cellular GPRS (carrier packet radio service) network, as shown in FIG. 1, a mobile station (MS) and a base transceiver station (BTS) controlled by a base station controller (BSC). Can occur when communicating between. The function of the CCU which is a channel codec unit based on GPRS is included in the BTS, and the function of the PCU which is a packet control unit based on GPRS is included in the BSC. Alternatively, in some embodiments, the PCU may not be located at the BSC, but may be located at the BTS or GSN (GPRS support node). Hereinafter, it is assumed that the PCU is located in the BSC.

  The ARQ protocol is used for the radio interface that forms the primary link between the mobile station MS and the GPRS network via BTS and BSC. A secondary link is formed by the Abis interface between the BSC and the BTS.

  According to conventional communication methods using ARQ, the PCU stores all data frames transmitted from the GPRS network until they are no longer needed. The exact time at which a transmitted data frame is no longer needed depends on the confirmation frame received from the mobile station MS for the transmitted data frame and the ARQ protocol used.

  When a data frame is transmitted, the PCU transmits it to the CCU via the Abis interface, and the CCU transmits the data frame to the mobile station MS via the radio interface. Retransmissions must be done in exactly the same way. Therefore, the same data frame must be transmitted many times through the Abis interface, which consumes communication resources.

  The object of the present invention is therefore to improve the retransmission of data frames in a distributed transmission device, which is a transmission device consisting of individual CCU and PCU units.

  According to a feature of the present invention, this object is a distributed transmission device in a communication system capable of requesting a retransmission of a data frame by a receiver MS, which transmits the data frame to the receiver MS and its transmission A transmission unit CCU for storing the transmitted data frame, a data frame to the transmission unit CCU for transmission to the receiver MS, and control data to control the retransmission of the data frame The control unit PCU is achieved by a distributed transmission device that controls the transmission unit CCU to retransmit the data frames stored in the transmission unit CCU to the receiver MS.

  According to another characteristic of the invention, the object is a transmission method of a distributed transmission device in a communication system in which a receiver MS can request retransmission of a data frame, the data frame being received by the receiver MS. Transmit from the control unit PCU to the transmission unit CCU, transmit the data frame from the transmission unit CCU to the receiver MS, store the transmitted data frame in the transmission unit CCU, and retransmit the data frame Transmitting the control data from the control unit PCU to the transmission unit CCU to control the transmission unit CCU, the transmission unit CCU retransmitting the data frame stored in the transmission unit CCU to the receiver MS. Is achieved by a transmission method controlled by.

  Furthermore, the object is a transmission unit CCU of a distributed transmission device in a communication system that can request retransmission of a data frame by a receiver MS, the distributed transmission device comprising a transmission unit CCU and a control unit PCU. The transmission unit CCU receives a data frame from the control unit PCU for transmission to the receiver MS, transmits the data frame to the receiver MS, and stores the transmitted data frame, and The transmission unit CCU receives control data from the control unit PCU to control retransmission of data frames, and retransmits the stored data frame to the receiver MS when there is a retransmission command from the control unit PCU. Accomplished by a transmission unit CCU configured to transmit.

  Furthermore, an object of the present invention is a control unit PCU of a distributed transmission apparatus in a communication system that can request retransmission of a data frame by a receiver MS, wherein the distributed transmission apparatus transmits to the control unit PCU. The control unit PCU transmits data frames to the transmission unit CCU for transmission to the receiver MS and transmits control data to the transmission unit CCU to control retransmission of the data frames; and The control unit PCU is achieved by a control unit PCU configured to control the transmission unit CCU to retransmit the data frame stored in the transmission unit CCU to the receiver MS.

  If the receiver MS does not receive the data frame correctly, the control unit PCU receives a retransmission request from the transmission unit CCU, which is transmitted by the receiver MS to the transmission unit CCU. .

  According to an embodiment of the invention, the control unit PCU adds an identification number to each data frame transmitted from the control unit PCU to the transmission unit CCU and uses this identification number to command retransmission of the data frame. To do. That is, the control unit PCU transmits the identification number of the data frame already transmitted and requested to the transmission unit CCU, and retransmits the requested data frame stored in the transmission unit CCU at the first transmission by the transmission unit CCU. To control retransmission.

  Alternatively, the control unit PCU defines a numbering sequence for each data frame transmitted from the control unit PCU to the transmission unit CCU, and commands retransmission of the data frame based on this numbering sequence.

  More specifically, the number of data frames is not transmitted, and they are based on counters provided in both the control unit PCU and the transmission unit CCU, for example. Each counter is incremented when a data frame is transmitted from the control unit PCU to the transmission unit CCU. The retransmission is performed by transmitting the difference between the requested data frame number or the current value of the counter of the control unit PCU and the requested data frame number from the control unit PCU to the transmission unit CCU. , By retransmitting the requested data frame to the receiver MS.

  Furthermore, according to the invention, the control unit is located remotely with respect to the transmission unit.

  The present invention is applicable to various ARQ protocols used for communications where a retransmission (one or more) is required by the receiver when a data frame is received in error. For example, the present invention is applicable to stop-and-weight ARQ protocol, go-back-N ARQ protocol, selective rejection ARQ protocol and hybrid ARQ protocol.

  In the present invention, the transmitted packet is stored not in the memory of the control unit PCU but in the memory of the transmission unit CCU. Therefore, the PCU does not need to send a packet to the CCU each time a retransmission is needed, but instructs the CCU to send a packet from the CCU's memory to the receiver. Thus, the PCU remains in full control of the ARQ protocol.

  According to one aspect of the present invention, in a base station for a distributed transmission device for a communication system that can request retransmission of a data frame by a receiver, the distributed transmission device includes the base station and the base station. A base station controller, the base station controller being remotely located with respect to the base station, the base station receiving a data frame from the base station controller for transmission to a receiver, The data frame received from the base station controller is transmitted to the receiver and the data frame received from the base station controller is stored, and the base station receives the control data for controlling the retransmission of the data frame. A base station is provided that receives from a station controller and retransmits a data frame from the stored data frame to the receiver based on the control data upon a retransmission command from the base station controller Is done.

  According to another aspect of the present invention, in a base station controller for a distributed transmission device for a communication system that can request retransmission of a data frame by a receiver, the distributed transmission device includes the base station. A controller and a base station, the base station controller being remotely located with respect to the base station, the base station controller transmitting a data frame to the base station for transmission to a receiver; The base station stores the data frame transmitted from the base station controller, and the base station controller transmits control data for controlling retransmission of the data frame to the base station, and Base station controller and controls the base station to retransmit to the receiver there is provided a data frame from the data frame stored in the over scan station based on the control data.

  According to still another aspect of the present invention, there is provided a transmission method in a base station for a distributed transmission device for a communication system capable of requesting retransmission of a data frame by a receiver, the distributed transmission device Comprises a base station and a base station controller, wherein the base station controller receives data from the base station controller for transmission to a receiver in a transmission method such as being remotely located with respect to the base station. A frame is received, a data frame received from the base station controller is transmitted to the receiver, a data frame received from the base station controller is stored, and control data for controlling retransmission of the data frame is stored in the base frame. And retransmitting a data frame from the stored data frame to the receiver based on the control data upon receiving a retransmission command from the base station controller. A transmission method is provided.

  According to still another aspect of the present invention, there is provided a control method in a base station controller for a distributed transmission device for a communication system, wherein a retransmission of a data frame can be requested by a receiver, the distributed transmission described above. An apparatus comprises a base station controller and a base station, wherein the base station controller transmits data to the base station for transmission to a receiver in a control method such as being remotely located with respect to the base station. Transmitting a frame, the base station stores the data frame transmitted from the base station controller, and transmits control data for controlling retransmission of the data frame to the base station. The data frames from the stored data frame to Shon based on the control data is controlled to retransmit to the receiver, the control method characterized by comprising the step of is provided.

  An advantage of the present invention is that the need for communication between the PCU and the CCU is reduced, i.e., the capacity of the secondary link is not wasted during retransmission. In the case of the cellular network shown in FIG. 1, the required Abis capacity is reduced.

  Furthermore, the present invention is effective in EGPRS (Enhanced General Packet Radio Service) where the use of IR (Incremental Redundancy) mode results in a very large number of retransmissions and the amount of data in each frame is large.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  In the GPRS network shown in FIG. 1, a packet control unit PCU is located at the base station controller BSC and a channel codec unit CCU is located at the base transceiver station BTS to form a distributed transmitter. The PCU communicates with the CCU via the Abis interface.

  The transmission of data frames from the GPRS network to the mobile station MS performed according to the present invention is described below with reference to FIG.

  Note that in the description of the present invention, the unit of transmission is referred to as a frame. However, the term frame should be understood to also include the meaning of the terms packet and block.

  When a data frame is first transmitted from the network to the MS, the PCU sends it to the CCU for transmission (step S1). Next, the CCU transmits a data frame to the MS via the radio interface and stores the data frame in a memory provided in the CCU (step S2).

  When retransmission is requested by the MS from the PCU via the BTS based on the ARQ protocol to be used, the PCU identifies the data frame for which retransmission has been requested (step S4). Upon identifying the requested data frame, the PCU retransmits only the signaling element, rather than retransmitting the entire frame over the Abis interface, and the CCU uses this to identify the requested data frame. (Step S5). The CCU then searches the memory for the requested data frame and transmits it to the MS over the primary link (step S6). The PCU is kept in full control of ARQ.

  The PCU will then explain how to signal the CCU which frame to retransmit.

  According to an embodiment of the present invention, the PCU adds an identification number to each frame transmitted from the PCU to the CCU. When retransmission is requested by the MS, the PCU sends the identification number of the data frame already transmitted and requested to the CCU. The CCU uses this identification number to identify the requested data frame in memory and retransmits the data frame to the MS.

  According to another embodiment of the invention, the PCU defines a numbering sequence for data frames sent to the CCU for transmission. The number is not transmitted to the CCU, and is based on, for example, a counter provided in both the PCU and the CCU. Each counter is incremented when a data frame is transmitted from the PCU to the CCU via the Abis interface. When retransmission is requested by the MS, the PCU transmits to the CCU the difference between the requested data frame number or the current value of the counter and the requested data frame number. The CCU identifies the requested data frame in memory based on the number sent from the PCU and retransmits the requested data frame to the MS.

  The CCU stores the transmitted data frame until the PCU commands the CCU to delete it. The timing of erasure depends on the confirmation frame received by the PCU from the MS and the ARQ protocol used.

  Furthermore, according to another method of erasing data frames in the CCU, the data frame is held in the CCU for a certain period of time, or the number of frames in the CCU memory is fixed and the old frame is replaced with a new frame. . In any case, no frame erasure signaling is required between the PCU and the CCU. This is because the PCU can calculate whether a frame is still present in the CCU memory. If the PCU determines that there are no frames in memory, the conventional method is entered, ie the PCU retransmits all frames.

  The present invention is also effective in EGPRS, particularly when the PCU is remotely located with respect to the BTS. In EGPRS, the use of IR (Incremental Redundancy) mode increases the number of retransmissions and the amount of data in each frame. When applying the present invention, the need to communicate all data frames from the PCU to the CCU or BTS is reduced, and the capacity of the Abis interface can be saved for other users, for example.

  While the present invention has been described with reference to preferred embodiments, this is merely illustrative of the invention and is not intended to limit the invention in any way. It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the true spirit and scope of the invention as defined in the claims.

  An advantage of the present invention is that the need for communication between the PCU and the CCU is reduced, i.e., the capacity of the secondary link is not wasted during retransmission. In the case of the cellular network shown in FIG. 1, the required Abis capacity is reduced.

  Furthermore, the present invention is effective in EGPRS (Enhanced General Packet Radio Service) where the use of IR (Incremental Redundancy) mode results in a very large number of retransmissions and the amount of data in each frame is large.

1 is a schematic block diagram illustrating elements of a cellular communication network related to the present invention. 3 is a flowchart of a retransmission method according to the present invention.

Explanation of symbols

BSC base station controller BTS base transceiver station MS mobile station PCU protocol control unit CCU channel coding unit

Claims (4)

  In a base station for a distributed transmission device for a communication system that can request retransmission of a data frame by a receiver, the distributed transmission device includes the base station and a base station controller, The base station controller is remotely located with respect to the base station, and the base station receives data frames from the base station controller and receives data frames received from the base station controller for transmission to a receiver. Storing the data frame transmitted to the receiver and received from the base station controller, the base station transmitting control data for controlling retransmission of the data frame to the base station controller And et received, the base station, wherein the retransmitting the data frame from the retransmission the stored data frame when the command from the base station controller to the receiver based on the control data.   In a base station controller for a distributed transmission device for a communication system that can request retransmission of a data frame by a receiver, the distributed transmission device includes the base station controller and a base station. The base station controller is remotely located with respect to the base station, the base station controller transmits a data frame to the base station for transmission to a receiver, the base station from the base station controller; The transmitted data frame is stored, and the base station controller transmits control data for controlling retransmission of the data frame to the base station and stored in the base station. Base station controller and controls the base station to retransmit to the receiver on the basis of the data frame from the data frame to the control data. A transmission method in a base station for a distributed transmission device for a communication system that can request retransmission of a data frame by a receiver, the distributed transmission device comprising: the base station; a base station controller; Wherein the base station controller is remotely located with respect to the base station in a transmission method,
Receive data frames from the base station controller for transmission to the receiver,
Transmitting the data frame received from the base station controller to the receiver, storing the data frame received from the base station controller;
Control data for controlling retransmission of a data frame is received from the base station controller, and a data frame from the stored data frame at the time of a retransmission command from the base station controller is received based on the control data. Re-send to instrument
A transmission method comprising the steps of: A control method in a base station controller for a distributed transmission device for a communication system capable of requesting retransmission of a data frame by a receiver, the distributed transmission device comprising: the base station controller; a base station; In the control method, wherein the base station controller is remotely located with respect to the base station,
Transmitting a data frame to the base station for transmission to a receiver, the base station storing the data frame transmitted from the base station controller;
Control data for controlling retransmission of the data frame is transmitted to the base station, and the base station retransmits the data frame from the data frame stored in the base station to the receiver based on the control data. Controlled to send,
A control method comprising the steps of:

Images