KR20070073538A - Method and system for controlling uplink channel coding scheme in a mobile communication system performing a dynamic channel assignment - Google Patents

Abstract

A method and a system for controlling an uplink channel coding scheme in a mobile communication system which executes dynamic channel assignment are provided to reduce an error rate as well as data rates by enabling a mobile terminal to change a channel coding scheme suitably according to rapid changes in channel circumstances. A mobile transmits a radio resource assignment request message to a base station in case user data or control information to be uplinked exists. The base station checks states of radio resources, based on the radio resource assignment request message. If it is judged that resource assignment can be executed, the base station creates the initial uplink TBF(Temporary Block Flow) and sets a TBF mode(701). Granting uplink transmission of the mobile terminal, the base station puts a USF(Uplink Status Flag) header, allocated to the mobile terminal, in a downlink RLC(Radio Link Control) block and transmits an RB(Radio Block) containing the RLC block to the mobile terminal(703-707). However, in case the created TBF is not the initial TBF, the base station judges channel circumstances through the RBs received from the mobile terminal, and determines coding schemes(CS-1~CS-4) for the next uplinked 4 RBs, respectively(709). Granting uplink transmission of the mobile terminal, the base station puts a USF header, allocated to the mobile terminal, in a downlink RLC block and transmits an RB containing the RLC block to the mobile terminal(711-715). At this moment, the base station downlinks RBs containing a combined USF, which indicates the determined coding schemes, to the mobile terminal(717).

Description

TECHNICAL AND SYSTEM FOR CONTROLLING UPLINK CHANNEL CODING SCHEME IN A MOBILE COMMUNICATION SYSTEM PERFORMING A DYNAMIC CHANNEL ASSIGNMENT}

1 is a diagram illustrating a structure of a packet transfer mode (PTM) multiframe in a general GPRS system

2 illustrates an uplink transmission operation using uplink slot allocation (USF granularity) in a general GPRS system;

3 is a flowchart illustrating the operation of a base station transmitting a USF in a general GPRS system

4 is a flowchart illustrating an operation of a terminal performing uplink transmission using a coding scheme allocated through USF in a general GPRS system.

5 illustrates an example of mapping a combined USF field and a coding scheme according to an embodiment of the present invention.

6 is a diagram illustrating an uplink transmission operation in a GPRS system according to an embodiment of the present invention.

7 is a flowchart illustrating an operation of a base station transmitting a combined USF in a GPRS system according to an embodiment of the present invention.

8 is a flowchart illustrating an operation of a terminal for performing uplink transmission with a coding scheme allocated through a combined USF in a GPRS system according to an embodiment of the present invention.

The present invention relates to a method and system for controlling a channel coding scheme in a mobile communication system, and more particularly, to a method and system for controlling an uplink channel coding scheme in a mobile communication system performing dynamic channel assignment. It is about.

In general, the mobile communication system performs data transmission and reception using a predetermined frequency band to ensure the user's activity. Such a mobile communication system has been rapidly developed in recent years, and this development is being made as the user's demand for data service such as wireless internet is increased from voice-oriented service. The difference between a voice-oriented mobile communication system and a system supporting data service is as follows.

Mobile communication systems supporting voice services should minimize time delay. In addition, the mobile communication system supporting the data service should minimize the error rate against the change of the wireless channel environment. Looking at a mobile communication system supporting existing data services, the General Packet Radio Services (GPRS) system based on the European system Global System for Mobile communication (GSM), and the CDMA 2000 based on North America's Code Divsion Multiple Access (CDMA) The technology is being developed and standardized in order to enable services using packet data protocols to existing mobile communication systems such as 1x systems.

Hereinafter, the present disclosure will be described, for example, as a GPRS system as a mobile communication system supporting data service and performing dynamic channel allocation.

The GSM system can allow multiple users to share the time slot of the RF carrier. Such shared transmission resources are managed by the base station, and a representative advantage obtained by introducing a packet data protocol in such a GPRS system is that data can be transmitted at a high data rate and the frequency band can be efficiently used. . Simply put, the concept of a GPRS system is that a "multi-slot operation" allows a user to occupy one or more transmission resources.

Packets transmitted in the GPRS system are mapped to one logical link control (LLC) frame, and the LLC frames are mapped to a plurality of Radio Link Control (RLC) blocks. The RLC block is again mapped to a radio block (RB) of a physical layer.

In addition, the GPRS system is based on a time division multiple access (TDMA) scheme, and a TDMA frame is the basis of all transmission operations. One TDMA frame is divided into eight time slots, and the time slot is a basic unit of data or control information transmission. Hereinafter, the TDMA frame will be referred to simply as a frame.

FIG. 1 is a diagram illustrating a structure of a packet transfer mode (PTM) multiframe in a general GPRS system. In FIG. 1, each block corresponding to a number from 0 to 51 represents one frame.

In general, in the PTM, the GPRS terminal is composed of four frame units in the remaining frames except for the T frames 11 and 15 and the I frames 13 and 17 in the repetition of 52 frames (0 to 51) as shown in FIG. Packet data and control information are transmitted and received using 12 radio blocks (RBs) B0 to B11, and timing correction and neighboring cells of a GPRS terminal using T frames 11 and 15 and I frames 13 and 17. Acquires synchronization information of a neighbor cell. Hereinafter, the term "terminal" in the present specification will be understood to mean a GPRS terminal.

If there is user data or control information to be transmitted on the uplink, the terminal transmits a message requesting radio resource allocation to the base station. When the base station checks the state of radio resources and allocates resources, the base station generates an uplink temporary block flow (TBF) to set the TBF mode and uplink packet assignment so that the terminal can use the PDCH. ) Send a message.

The uplink packet allocation message includes an uplink slot allocation (USF granularity) field to allow a terminal to use a plurality of radio blocks (RBs) for uplink transmission per uplink status flag (USF). The terminal receiving the uplink packet allocation message transmits user data or control information using the RB allocated to the corresponding terminal among the radio blocks R0 to B11. The USF of the PDCH is used when multiplexing the RBs transmitted uplink from multiple terminals to the base station. The USF included in the initial transmission of each RB in the downlink is composed of three bits of information bits to distinguish eight (2 ³ ) USF states. As described above, the GPRS system can multiplex uplink traffic according to the information bits of the USF.

In the case of downlink, a base station of a GPRS system transmits data by changing a coding scheme according to a wireless channel state, and a terminal receives data received from the base station through a stealing flag of a normal burst. Determine the coding scheme. In the case of uplink, the coding scheme to be used by the terminal when the TBF is allocated at the base station is determined, and the terminal must continue to use the predetermined coding scheme unless the TBF configuration is changed by the control information transmitted from the base station.

In a GPRS system in which a coding scheme is determined according to the above scheme, PDCH allocation methods for packet data transmission are classified into fixed allocation, dynamic allocation, and extended dynamic allocation. If the dynamic allocation method or the extended dynamic allocation method is applied and the USF allocated through the base station is found, the interval for allowing uplink transmission of the terminal through the USF is one RB unit. However, when uplink slot allocation (USF granularity) is set together, transmission is performed during four RB intervals when the allocated USF is decoded.

That is, the UE checks the availability of uplink transmission resources by looking at the USF of the downlink channel, and checks the setting of uplink slot allocation (USF granularity) and transmits data during the corresponding RB interval in the next uplink.

2 is a diagram illustrating an uplink transmission operation using uplink slot allocation (USF granularity) in a general GPRS system.

In FIG. 2, reference numerals B0 to B7 denote RBs, and FIG. 2 shows that uplink slot allocation (USF granularity) is set and the terminal decodes the USF received from the base station. Illustrating the operation of performing uplink transmission with the proposed coding scheme.

3 and 4, the operation of the base station transmitting the conventional USF and the operation of the terminal receiving the USF and performing uplink transmission will be briefly described.

3 is a flowchart illustrating an operation of a base station transmitting a USF through a downlink of a general GPRS system.

First, if there is user data or control information to be transmitted on the uplink, the terminal transmits a message requesting radio resource allocation to the base station, and if the base station checks the state of the radio resource and allocates resources, the terminal transmits the uplink in step 301. Create an uplink temporary block flow (TBF) for the TBF mode. The base station includes the USF header allocated to the terminal in the downlink RLC block in step 303, and transmits the RB including the RLC block to the terminal in step 305.

FIG. 4 is a flowchart illustrating an operation of a terminal performing uplink transmission using a coding scheme allocated through USF in a general GPRS system.

The terminal receives and decodes the USF from the downlink RLC block transmitted from the base station in step 401, and checks whether there is a USF allocated to the decoded USF in step 403. If the terminal finds the USF allocated to the UE, in step 405, the terminal divides the RLC block to be transmitted using the coding scheme assigned to the USF. In step 407, the terminal performs channel encoding using a coding scheme assigned to the USF, and then performs uplink transmission.

In the conventional GPRS system, the terminal transmits data through a PDCH allocated by a fixed allocation, dynamic allocation, or extended dynamic allocation method when transmitting packet data as described above, and the attribute of the uplink TBF generated through the base station is TBF generated. The channel coding scheme is also determined in this process. When receiving the PDCH in the downlink, it is possible to change the channel coding scheme in RB units according to channel conditions through a stealing flag included in a normal burst.

Therefore, even in the uplink, there is a method of changing the coding scheme according to the channel situation, but since this is performed through an RLC control block (not shown) in the terminal, transmission of control information is additionally required during data reception. Like the link, the channel coding scheme cannot be controlled in units of RBs, so there is a problem in that it cannot adapt to rapid channel environment changes.

The present invention provides a method and system for controlling uplink channel coding scheme in a mobile communication system performing dynamic channel allocation.

The present invention provides a method and system for controlling uplink channel coding scheme suitable for fast channel environment change in a mobile communication system performing dynamic channel allocation.

The method of the present invention is a method for controlling uplink channel coding scheme of a mobile communication system that performs dynamic channel allocation, wherein a base station receiving a radio resource allocation request for uplink transmission from a terminal is based on a radio block received from the terminal. Determining a low channel state, the base station pre-determining a coding scheme of a plurality of radio blocks next uplinked from the terminal according to the determined channel state, and the base station performing the determined coding scheme The notifying includes downlink transmission of the plurality of radio blocks to which the combined uplink status plug USF is allocated to the terminal.

In the mobile communication system performing dynamic channel allocation, the system of the present invention receives a radio resource allocation request for uplink transmission from a terminal and determines a channel state based on a radio block received from the terminal. A plurality of radio blocks to which a combined uplink status plug (USF) assigned a combined uplink status plug (USF) indicating a coding scheme of a plurality of radio blocks next uplink transmitted from the terminal according to a channel state are respectively determined in advance. And a terminal for channel-transmitting the plurality of radio blocks according to a coding scheme identified through the combined uplink status plug and transmitting the uplink.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

First, the basic concept of the present invention, when the base station is set uplink slot allocation (USF granularity), the USF allocates a coding scheme to be applied to the RB transmitted uplink by identifying the channel environment through the packet data received from the terminal Notifies the terminal through the USF field of the remaining RB rather than the RB. Thereafter, the RB transmitted uplink is decoded using a coding scheme informed to the terminal. The terminal checks the USF field of the remaining three RBs, not the RBs to which the USF is actually allocated, obtains a coding scheme designated by the base station, splits the RLC block according to the specified coding scheme, performs channel encoding, and then uplinks the packet. send.

The present invention uses a dynamic allocation method or an extended dynamic allocation method as a PDCH allocation method for packet data transmission, is applied when uplink slot allocation (USF granularity) is set, and the following base station operation and terminal operation are required. . In more detail, the dynamic allocation method or the extended dynamic allocation method is described. In the fixed allocation method, an RB for PDCH transmission is determined by a network such as a base station, whereas the USF is included in all RBs in the downlink. Use dynamic resource allocation. In the dynamic allocation method, the terminal decodes the USF header of the RLC block received through the RB, and if the decoding result is the same as the USF value assigned to the terminal by the network such as a base station, the next RB is allocated to be used for PDCH transmission. This is how you do it.

The extended dynamic allocation method is used when the RB reception for decoding the USF of the time slot allocated for transmission cannot be performed due to the limitation of the multi-slot class. If a read USF value is found, the method also allows PDCH transmission for the next RB configured with a higher number of time slots, including the next RB of the corresponding slot. When the dynamic allocation method or the extended dynamic allocation method is used, uplink slot allocation (USF granularity) may be used.

In addition, if the uplink TBF is set up with uplink slot allocation (USF granularity) as dynamic allocation or extended dynamic allocation, the terminal uses the original assigned coding scheme to send packets for the next four RB intervals of the USB allocated RB. Will be sent. Upon receiving this, the base station determines a channel condition and allocates the determined coding scheme to the USF fields of three consecutive RBs after the RB to which the USF is allocated.

5 is a diagram illustrating a mapping example of a combined USF field and a coding scheme according to an embodiment of the present invention.

In FIG. 5, since one USF field is composed of 3 bits, the usable bits through three consecutive RBs are 9 bits in total. In the coding scheme, four of CS-1, CS-2, CS-3, and CS-4 exist. In order to express four coding schemes, two bits of information per RB are required. Therefore, a total of 8 bits required to represent a coding scheme for four RBs can be represented by a combination of three USF field values obtained from three RBs. After the base station receives the uplink transmitted packet from the terminal to determine the channel condition, the terminal determines one of the four coding schemes for each of the next four RBs to be transmitted and transmits it through the USF header. 5 schematically shows an example of mapping between three USF field values USF1, USF2, and USF3 and four coding schemes CS-1 to CS-4.

6 is a diagram illustrating an uplink transmission operation in a GPRS system according to an embodiment of the present invention.

In FIG. 6, the base station transmits a coding scheme determined to the terminal by using the combined USF field through three RBs, as described with reference to FIG. 5, and the terminal decodes the combined USF field and then transmits four RBs. Determine a coding scheme for to perform uplink transmission.

When the base station transmits a coding scheme using the USF field, for example, CS-1 maps to "1", CS-2 maps to "2", CS-3 maps to "3", CS-4 maps to "4", and " 0 "represents the coding scheme determined through the control message. In order to check whether the resource is allocated for uplink transmission, the terminal always checks the USF transmitted from the base station, and if it finds an RB including the allocated USF, four consecutive RB transmission blocks B0 to B3 and B4 to For B7), the transmission using the previously obtained coding scheme information.

At this time, the UE receives the first, second, and third RBs of the four RBs, and uses four combined schemes (CS-1 to CS) to be used for the packet to be transmitted when the next USF allocation is detected through the combined USF field 61. -4) is obtained. The decoded coding scheme is first used for splitting the RLC block to send. Since the uplink transmission is operated by repeating the above process, the coding scheme can be adaptively changed even in a fast channel change situation.

For example, suppose that a coding scheme is applied in order of CS-1 to CS-4 for four RBs. As shown by reference numeral 63a, the terminal transmits an uplink using CS-1 as a coding scheme for a B4 block. Do this. In addition, as shown by reference numerals 63b, 63c, and 63d, the terminal performs uplink transmission using CS-2, CS-3, and CS-4 as coding schemes for blocks B5, B6, and B7, respectively.

Hereinafter, an operation of a base station for transmitting a combined USF and an operation of a terminal for receiving a combined USF and performing uplink transmission will be described with reference to FIGS. 7 and 8.

7 is a flowchart illustrating an operation of a base station transmitting a combined USF in a GPRS system according to an embodiment of the present invention.

First, if there is user data or control information to be transmitted on the uplink, the terminal transmits a message requesting radio resource allocation to the base station, and if the base station checks the state of the radio resource and allocates the resource, the terminal transmits the uplink in step 701. A TBF mode is set by generating an initial uplink temporary block flow (TBF). If the base station allows uplink transmission in step 703, the base station proceeds to step 705 to include the USF header allocated to the terminal in the downlink RLC block, and transmits the RB including the RLC block to the terminal in step 707. .

Since the USF transmitted to the terminal through the operations of steps 701 to 707 is an initial USF transmitted to the terminal, the base station does not determine the coding scheme in consideration of the channel situation. In this case, it may be possible for the base station to transmit the default value of the predetermined USF.

If the temporary block flow (TBF) generated in step 701 is not the first TBF, the base station proceeds to step 709 to determine the channel condition through the RBs received from the terminal, the terminal of the next four blocks uplink transmission The coding schemes CS-1 to CS-4 are determined for the RBs, respectively. If the base station allows uplink transmission in step 711, the base station proceeds to step 713 to include the USF header allocated to the terminal in the downlink RLC block, and transmits the RB including the RLC block to the terminal in step 715. . At this time, the base station includes the coding scheme determined through the step 709 of the coding schemes CS-1 to CS-4 in the combined USF in the downlink RLC blocks of the RB interval in which uplink transmission is allowed, as in step 717, respectively. send.

8 is a flowchart illustrating an operation of a terminal for performing uplink transmission with a coding scheme allocated through a combined USF in a GPRS system according to an embodiment of the present invention.

The terminal receives and decodes the USF from the downlink RLC block transmitted from the base station in step 801, and checks whether there is a USF allocated to the decoded USF in step 803. If the UE finds the USF assigned to the UE, in step 805, it is determined whether the RB transmission is the first transmission after generating the uplink TBF, and if it is determined that the transmission is the first transmission, the terminal proceeds to step 807 and the coding scheme assigned to the USF. Split the RLC block to be transmitted using.

Here, the terminal can check whether the RB transmission is the first transmission as follows. That is, the terminal changes a predetermined state flag to "start" when generating a TBF. And if the USF assigned in step 803 is found and the state flag is "start", the state flag is changed to "first matched", and if the assigned USF is found and the state flag is "first matched", the state is "multiple matched". Change the flag. In step 805, the terminal checks whether the status flag is "first matched", and if it is "first matched", proceeds to step 807, otherwise proceeds to step 813. The terminal changes the status flag to "finished" at the end of TBF.

In step 809, the terminal performs channel encoding using a coding scheme assigned to the USF, and then performs uplink transmission. At this time, the UE acquires the coding schemes CS-1 to CS-4 through the USF field in step 811 to split and transmit the RLC block, but in the case of transmission according to the initial TBF generation, the terminal has not yet received the combined USF from the base station. Therefore, the terminal may separately obtain coding schemes CS-1 to CS-4 for initial transmission through signaling with the base station, or may use a coding scheme determined by default with the base station.

On the other hand, if it is determined in step 805 that it is not the first RB transmission after generating the uplink TBF, the terminal proceeds to step 813 to perform channel encoding using the coding schemes CS-1 to CS-4 obtained in the previous transmission. Then, uplink transmission is performed. Here, the USF decoded and used by the terminal is a combined USF (see reference numeral 61 of FIG. 6) obtained from three RBs in a previous transmission.

As described above, according to the present invention, when a channel environment changes in a mobile communication system that performs dynamic channel allocation, the terminal does not transmit a separate control message to the base station while reducing the data rate to change the channel coding scheme. By changing the coding scheme in units of RB and changing the coding scheme in response to a rapid channel environment change, the data rate can be reduced and the error rate can be reduced.

Claims (11)

In the uplink channel coding scheme control method of a mobile communication system performing dynamic channel allocation, Determining a channel state by a base station receiving a radio resource allocation request for uplink transmission from a terminal based on a radio block received from the terminal; Determining, by the base station, a coding scheme of a plurality of radio blocks, which are next uplinked from the terminal, according to the determined channel state in advance; And transmitting, by the base station, downlink transmission to the terminal of a plurality of radio blocks to which a combined uplink status plug (USF) for informing the determined coding scheme is allocated. The method of claim 1, And said combined uplink status plug is downlink transmitted over a plurality of successive radio blocks. The method of claim 1, The combined uplink status plug is used when uplink slot allocation (USF granularity) is set. The method of claim 3, wherein When performing uplink transmission in units of four radio block intervals according to the uplink slot allocation, the combined uplink status plug is allocated to the remaining three radio blocks except for the radio block in which the existing uplink status plug is disposed. Uplink channel coding scheme control method characterized in that it is represented by a successive combination of three uplink state plugs. The method of claim 4, wherein One uplink status plug contains 3 bits of information bits, And said combined uplink status plug represents a coding scheme for four radio blocks with two bits of information per radio block. The method of claim 1, And transmitting the channel by uplinking each of the plurality of radio blocks according to the coding scheme identified through the combined uplink status plug, and transmitting the uplink channel coding scheme. In a mobile communication system for performing dynamic channel allocation, Receiving a radio resource allocation request for uplink transmission from the terminal and determining a channel state on the basis of the radio block received from the terminal, and according to the determined channel state of the next plurality of radio blocks to be transmitted upstream from the terminal A base station for pre-determining a coding scheme and downlink transmitting a plurality of radio blocks to which the combined uplink status plug (USF), which is notified of the determined coding scheme, is assigned; And a terminal configured to channel-transmit the plurality of radio blocks according to the coding scheme identified through the combined uplink status plug and to transmit the uplink channel coding scheme. The method of claim 7, wherein The base station performs uplink channel coding scheme control, characterized in that the downlink transmission through a plurality of radio blocks successive to the combined uplink status plug. The method of claim 7, wherein And the base station uses the combined uplink status plug when uplink slot allocation (USF granularity) is set. The method of claim 9, When the base station performs uplink transmission in units of four radio block intervals according to the uplink slot allocation, the combined uplink status plug has three remaining radio blocks except for a radio block in which an existing uplink status plug is disposed. A mobile communication system for performing uplink channel coding scheme control, characterized in that it is represented by successive combinations of three uplink state plugs assigned to. The method of claim 10, One uplink status plug contains 3 bits of information bits, The combined uplink status plug is a mobile communication system for performing uplink channel coding scheme control, characterized in that the coding scheme for four radio blocks with two bits of information per radio block.

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