KR100969777B1 - Forward data rate control method in mobile communication system - Google Patents

Abstract

The present invention provides a method for controlling a forward data rate in a base station of a mobile communication system that transmits packet data to a terminal having a best reception state among a plurality of terminals, the method comprising: a rate change factor for changing the forward data rate; Generating data rate adjustment information simultaneously applied to the terminals, and transmitting the generated data rate adjustment information to the terminals; and transmitting the generated data rate adjustment information to the terminals in a pilot reception intensity range adjusted by the data rate adjustment information. And receiving a corresponding data rate control value and transmitting the packet data to a terminal having the best reception state according to a data rate corresponding to the received data rate control value. As a result, the base station can determine the desired data rate control value and reflect it in the forward data rate, and consider the QoS parameters required for each service or user, thereby improving overall system performance. .

1xEV-DO, DRAI, DRC, Forward Data Rate, Forward Forward Target Error Rate.

Description

Forward data rate control method in mobile communication system             

1 is a block diagram showing the structure of a typical 1xEVDO system;

2 is a flowchart illustrating an operation of establishing a session according to an embodiment of the present invention;

3 is a flowchart illustrating an operation of receiving a DRAI in a terminal according to an embodiment of the present invention;

4 illustrates an example in which a DRC table is changed according to DRAI reception according to an embodiment of the present invention;

5 is a flowchart illustrating an operation for maintaining a forward target error rate according to another embodiment of the present invention;

6 is a flowchart illustrating an operation of transmitting a DRC in a terminal according to an embodiment of the present invention.

The present invention relates to a method for transmitting packet data in a mobile communication system, and more particularly, to a method for controlling a transmission rate of forward packet data that a terminal intends to receive.

Recently, a lot of researches have been conducted for high-speed data transmission in a code division multiple access (Mobile Access) system. A typical mobile communication system having a channel structure for such a high speed data transmission is a 1x EVDO (1x EVolution Data Only) system. The 1xEVDO system is a mobile communication system of a standard proposed by 3GPP2 (3rd Generation Partnership Project 2) to supplement data communication of the IS-2000 system.

Looking at the configuration of the forward channel of the 1xEVDO system, the time division multiplexing of the pilot channel, the forward medium access control (MAC: MAC) channel, the forward traffic channel and the forward control channel, etc. do. In this case, a bundle of time division multiplexed signals is referred to as a burst.

User data packets are transmitted in the forward traffic channel, and control messages and user data packets are transmitted in the forward control channel. The forward MAC channel is used to transmit reverse rate control and power control information or a designated channel for forward data transmission.

Unlike the forward channel, the reverse channel of the 1xEVDO system has a channel with different identification codes for each terminal, and the reverse channel for each terminal includes a pilot channel, a reverse traffic channel, a reverse MAC channel, and an access channel. User data packets are also transmitted in the reverse traffic channel, and the reverse MAC channel includes a data rate control (DRC) channel, a reverse rate indicator (RRI) channel, and the like. The access channel is used when the terminal transmits a message or traffic to the base station before the traffic channel is connected.

The structure and rate control operation of the 1xEVDO system and its related channel will be described with reference to FIG. 1 as follows.

Referring to FIG. 1, a 1xEVDO system is connected to the Internet network and transmits a packet data service node 40 (hereinafter referred to as a PDSN) 40 to transmit high-speed packet data to the base station 20, and the base station 20 ) Is configured as a base station controller (Access Node Control: ANC) (30). The base station 20 wirelessly communicates with the plurality of terminals 10 and transmits the high speed packet data to the terminal 10a having the best transmission rate.

In the case of the rate control of the forward channel, the terminal 10 measures the reception strength of the pilot transmitted by the base station 20 so that the terminals 10 are determined according to a predetermined fixed value based on the measured reception strength of the pilot. Determine the forward data rate you want to receive. The terminal 10 transmits DRC information corresponding to the determined forward data rate to the base station 20 for each predetermined slot. Then, the base station 20 receives the DRC information and transmits packet data by adjusting the data rate only to the terminal 10a having a good state. In this case, the DRC information refers to a value indicating a value obtained by converting a transmission rate that the terminal can transmit in a forward direction by measuring a channel state. The DRC information may vary depending on the implementation, but is to use a fixed value in the terminal manufacturing process.

The 1xEVDO scheme is a transmission scheme that greatly improves the data throughput of the forward link. The 1xEVDO scheme has a maximum power of a base station and changes the length of a packet using a single transmission shared channel. Send the data. If the channel condition is bad, a small amount of data is transmitted per unit time. That is, the 1xEVDO system transmits data through a data transmission shared channel to only one terminal at the same time among all the terminals in the base station.

Unlike the forward link, the reverse link has a channel having a different identification code for each terminal, and the terminal can transmit at a desired transmission rate. This reverse link is provided with a method for the upper limit transmission rate and overload control. The base station reports the upper limit rate for each terminal to the terminal through a reverse rate limit message (ReverseRateLimit Message), and the overload control for each slot through the reverse activity bit (RAB: RAB) of the MAC channel in the forward slot Report to the terminal. In this case, the RAB is intended for overload control through rate control in the transmission of reverse link traffic. If the RAB is '0', the UE can double or maintain the reverse rate, and the RAB If the value is '1', the terminal that is transmitting data at a transmission rate of 19.2kbps or more reduces or maintains the transmission rate of the reverse link to 1/2.

In the 1xEVDO system as described above, the base station transmits forward traffic at the data rate transmitted by the terminal to the scheduled terminal. That is, the terminal determines the forward data rate, and the base station uses the data rate required by the terminal as it is. However, in this manner, the channel state or network state determined by the base station cannot be broadcasted, and the maximum performance of the system is degraded because the base station does not consider the characteristics of the service to be transmitted or the user-specific characteristics. In addition, since only the channel characteristics set in the same manner are applied to the quality of service (QoS) that is differently required for each user or service, there is a problem in that the characteristics of each user and service cannot be sufficiently considered.

Accordingly, an object of the present invention is to provide a method for controlling a forward data rate determined by a terminal at a base station in a forward rate control in a 1xEVDO system.

Another object of the present invention is to provide a transmission rate control method for transmitting a transmission rate determination table, transmission rate correction information, and transmission error rate information to all terminals using a broadcast message.

Another object of the present invention is to provide a transmission rate control method for transmitting a transmission rate determination table and transmission error rate information for each terminal by using session setting attribute information stored for each terminal.

Another object of the present invention is to provide a transmission rate control method for transmitting a transmission rate determination table, transmission rate correction information, and transmission error rate information to a terminal using a unicast message.

The method for achieving the object of the present invention is a method for controlling the forward data rate in the base station of the mobile communication system for transmitting packet data to the terminal having the best reception state of the plurality of terminals, the forward data rate Transmitting the generated data rate adjustment information or transmission error rate information to the terminals by generating data rate adjustment information or transmission error rate information simultaneously applied to the terminals according to a rate change factor for changing a value; Receiving a data rate control value corresponding to a pilot reception strength range adjusted by the data rate adjustment information or the transmission error rate information from the data rate control unit, and transmitting the packet data according to the data rate corresponding to the received data rate control value. Terminal with the best reception It characterized in that it comprises the step of transmitting.

According to another aspect of the present invention, there is provided a method for controlling a forward data rate in a mobile communication system for transmitting packet data to a terminal having a best reception state among a plurality of terminals, according to the rate change factor. Generating data rate adjustment information or transmission error rate information applied to each terminal, and transmitting the generated data rate adjustment information or transmission error rate information to each of the terminals; and transmitting the data rate adjustment information or transmission error rate from the terminals. Receiving a data rate control value corresponding to a pilot reception intensity range adjusted by information, and transmitting the packet data to a terminal having the best reception state according to a transmission rate corresponding to the received data rate control value Characterized in that it comprises a.

The method for achieving the object of the present invention is a method for controlling the forward data rate in the base station of the mobile communication system for transmitting packet data to a plurality of terminals, corresponding to the range of the pilot reception strength of the base station Receiving a data rate control table including set data rate control values and data rate adjustment information or transmission error rate information generated according to a rate change factor from the base station, and applying the received data rate adjustment information or transmission error rate information And adjusting a range of the pilot reception strength of the rate control table, determining a data rate control value corresponding to the pilot reception intensity currently measured in the adjusted data rate control table, and determining the determined data rate control value. Said group It characterized in that it comprises the step of transmitting to the station.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used for the same reference numerals even though they are shown in different drawings. Also, in the following description, many specific details such as components of specific circuits are shown, which are provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. It will be self-evident to those of ordinary knowledge. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, referring to FIG. 1, the 1xEVDO system for controlling a forward data rate requested from a terminal by a base station according to an embodiment of the present invention will be described.

Referring to FIG. 1, the 1xEVDO system includes a base station 20 that communicates with a plurality of terminals 10. The terminal 10 has a data rate control (DRC: DRC) table for determining a forward rate.

The base station 20 transmits data through a transmission rate correction information (DRAI: DRAI) through an overhead message transmitted in a forward direction or a setting attribute of a MAC layer protocol and a MAC layer protocol message. ) Is transmitted to the terminal 10a having the best state among the terminals 10a, 10b, and 10c.

The terminal 10a adjusts the values of the DRC table to values within a range set by the base station 20 using the DRAI received from the base station 20. In addition, the strength of the received pilot is measured to transmit the DRC information corresponding to the measured pilot strength in the DRC table to the base station 20.

In order to control the forward data rate in the 1xEVDO system having such a structure, the DRC table and the DRAI are transmitted to the UE to adjust boundary values of the DRC table. In the present invention, the DRAI is transmitted to the UE by using a broadcast type message, a configuration attribute, and a unicast message to transmit the DRC table and the DRAI, and the DRAI transmission operation using these methods will be described as follows.

First, instead of considering the service of the terminal or the characteristics of the terminal, a method of using a broadcast message according to a rate change factor may be considered. Here, the rate change factor is state information of a base station, and information such as interference between the base station and other base stations, traffic amount of the base station and base station control period, and inter-sector interference in the base station.

In the case of transmitting the DRC table and the DRAI using the broadcast type message, all terminals in the base station have the same DRAI value. That is, in this case, all the terminals obtain the DRC value to be reported to the base station by applying the same boundary value to the pilot carrier / interference (C / I) information of the received base station.

The base station transmits the DRC table and DRAI determined by the base station to all the terminals in the base station using a broadcast message. As an example of transmitting the DRC table and the DRAI through the broadcast message, a DRC table message (hereinafter referred to as a DRCTM) and a rate correction information, which are forward link traffic channel MAC protocol messages, are transmitted. The DRC table and the DRAI are transmitted to the terminal through a message (hereinafter referred to as DRAIM). Here, the DRCTM and DRAIM are transmitted to the terminal through a forward control channel. In addition, the DRC suitable for the strength of the pilot signal received through the physical layer is determined, and in order to use the DRC table information received in the MAC protocol, the DRC table and DRAI are defined as public data so that the physical layer protocol determines the DRC. Make table information and DRAI available. The DRC table is set to an appropriate initial value in advance in implementation.

Since the broadcast message is transmitted to all terminals, all the terminals have the same DRC Table and DRAI values. That is, in this case, all the terminals apply the same boundary value to the received pilot C / I information of the base station to obtain a DRC value to report to the base station. A structure of the MAC layer header of the forward control channel is shown in Table 1 below.

In Table 1, the Length field indicates the length of the header (8 bits), and the ATI Record field is a field for specifying the address of the terminal and is set to 2 bits '00' when indicating that the message is a broadcast message.

The structure of the DRCTM is as shown in Table 2 below, and the description of the DRCTM is as follows.                     

In Table 2, the MessageID field indicates an identifier value corresponding to DRCTM, and the DRC0 field indicates that a boundary value corresponding to DRC0 of the DRC table is specified in steps of 255 in 0.125 dB units. The boundary value here has a value between -20 dB and 11.875 dB. That is, when the DRC0 value is 0, the base station reports the DRC value '0' to the UE when the pilot power of the base station is -20 dB or less and the threshold value is -20 dB. In this way, when DRC0 is 1, -19.875 dB is set as the boundary value, and when 255 (0xFF) is 11.875 dB.

The FixedDRCGap field indicates whether the boundary value range of each DRC value is the same. Herein, when the FixedDRCGap field is 1, all DRC values have the same range. In this case, the DRCGap field indicates that the range is specified in units of 0.125 dB when each DRC value has the same range. For example, when the value of the DRC0 field is 01010000 (0x50 = 80) and the FixedDRCGap field is 1, and each DRC fields have the same range [from -10 dB to the same range], the value of the DRCGap field is 1000 (0x8). ), The range of each DRC value is 1 dB. In this case, the DRC table is shown in Table 3 below.

In Table 2, when the FixedDRCGap field is 0, a different range value for each DRC value is specified using the DRC1Gap to DRCEGap fields in 16 steps of 0.125 dB.

Meanwhile, the structure of the DRAIM is as shown in Table 4 below, and the DRAIM will be described as follows.                     

In Table 4, the MessageID field indicates an identifier value corresponding to DRAIM. The DRAIMessageSequence field represents sequence information between several DRAIMs transmitted, and the base station configures the DRAIM by increasing the value of the DRAIMessageSequence field by 1 for each DRAIM transmission.

In addition, the DataRateAdustmentInformation field is an 8-bit field representing the value of DRAI, and the information represented by the 8-bit may vary according to implementation. The structure of the DataRateAdustmentInformation field is shown in Table 5 below.

Bit name Length (bits)   Sign One   Delta 7

In Table 5, one bit of the eight bits is set as a sign bit and seven bits are set as a delta bit. The Sign bit is a bit indicating whether to add or subtract a value representing a Delta bit to boundary values corresponding to each DRC when obtaining a DRC value using the measured C / I. In other words, if the Sign bit is 0, it can be interpreted as adding a Delta value, and if it is 1, subtracting it. The Delta bit represents the size of a value to be added to the boundary of the DRC in a predetermined unit. For example, when expressed in units of 0.025 dB, the 8-bit DataRateAdjustmentInformation field corrects the transmission rate by adding or subtracting values ranging from -3.175 dB to 3.175 dB to the boundary value of the DRC.

On the other hand, unlike the method using the broadcast message, in the case of a service having a high time constraint such as a real-time service, the initial transmission error rate can be further lowered to prevent an increase in delay due to an error occurring in the initial transmission. In this case, since the characteristics of the service or the terminal are considered, the MAC layer protocol configuration attribute and the unicast message are used. Here, the rate change factor is information known to the base station, transmission requirements for each user (terminal information, service type, service quality), and the like.

When defining a DRC table with a value of session configuration information stored for each terminal and using a different DRC table for each terminal, the MAC layer protocol configuration attribute is used to control the DRC table.

All protocols of the 1x EVDO system determine protocol-specific parameter settings to be used in the system when a session is established. When a session is opened with one of these settings, the DRC table is used as a configuration attribute of a MAC protocol (for example, a forward traffic channel MAC protocol). That is, when the power of the terminal is turned off and on again or the session setting value is changed, the session parameters are reset. In this case, the base station may set a value of the DRC table to be used for each terminal. In this case, protocol setting values may be different for each base station. If the setting value is changed, the protocol setting values must be negotiated again to set the DRC value. A structure of a complex configuration attribute record of a forward traffic channel MAC protocol defined as a DRC table attribute when using such a configuration attribute is shown in Table 6 below. The following describes the type setting record.

In Table 6, the Length field of the record has a value indicating the length of the record except for the Length field in octets, and the AttributeID field has a preset value as a DRC table attribute. In addition, the ValueID field represents identifiers of attribute values to be provided, and the DRC0 to DRCEGap fields have the same meanings as the DRC0 to DRCEGap fields of Table 2 and have initial values determined according to each implementation.                     

An operation of exchanging such setting attributes will now be described with reference to the accompanying drawings.

2 is a flowchart illustrating an operation of establishing a session according to an embodiment of the present invention.

Prior to establishing an initial session between an access terminal and an access network, in step 200, the terminal transmits a message (UATIRequest) requesting a unicast address (Unicast Access Terminal Identifier) to the base station. Accordingly, the base station transmits a message (UATIAssignment) for setting the unicast address to the terminal to set the unicast address.

Then, in step 230, the terminal and the base station determines the configuration properties, when the connection configuration is complete. The process of determining the configuration attributes is divided into two parts in which the base station processes configuration property request values of the terminal and two parts in which the terminal processes configuration request values of the base station.

In step 240, the base station transmits a message (ConfigurationStart) to start the determination of the session configuration attribute to the terminal. The terminal then sends a configuration prompt completion message (ConfigurationComplete). Then, in step 230, the terminal and the base station exchanges keys. Then, the request value of the base station is processed after requesting the configuration attribute of the terminal. In this example, the base station transmits a message (ConfigurationRequest) including a DRC table to the terminal to process the requested configuration attribute value (step 270).                     

After processing the request value of the base station, the terminal transmits a response message (ConfigurationResponse) in step 280. Accordingly, the base station transmits a configuration attribute completion message (ConfigurationComplete). After the negotiation of such session attributes, the terminal and the base station re-initialize the protocol, which has been initialized to the default configuration attribute values for session establishment, by applying newly set attributes and apply new configuration values.

The added configuration attribute may be defined as public data of a corresponding protocol to report a DRC corresponding to a DRC table configured in a physical layer that sets and transmits an actual DRC value.

On the other hand, if a different DRC table or DRAI value is set for each terminal, and the base station and the terminal change the type of transmitted data or the quality of service (QoS) parameter value during the data transmission process, the unicast (Unicast) Use a message.

The unicast message adjusts the DRC table to perform initial rate correction appropriate for the service.

The base station adjusts the DRAI value and performs DRC table and DRAI through the data rate control table message (DRCTM) and the data rate adjustment information message (DRAIM), which are forward traffic channel MAC protocol messages, to perform the initial transmission rate correction appropriate for the QoS. Send to the terminal. Here, the DRAI may be transmitted through a forward control channel or a forward traffic channel in the form of a unicast message for each terminal. Unlike the case of using the configuration attribute when using the MAC protocol messages, there is no need to reconfigure the data channel when the DRC table and the DRAI are changed during the transmission process. In this case, the terminal defines the DRC table and DRAI as public data to use the DRC table information received by the MAC protocol so that the physical layer protocol can use the DRC table information and DRAI. The DRC table may be set to an appropriate initial value in advance when implemented.

The structure of the DRCTM and the DRAIM in the case of using such a unicast message is as shown in Tables 2 and 4, and the description of the DRCTM and the DRAIM includes the DRCTM of the method using the broadcast message. As it is the same as the description of DRAIM, it is omitted.

The forward rate control operation is described by applying the above schemes.

The base station determines the value of the DRAI by reflecting the rate change factor according to the influence of the neighboring cells, or the base station determines the value of the DRAI in consideration of the transmission characteristics (QoS parameters) required for each service or user. In this case, when data is transmitted at a transmission rate higher than the value set in the initial DRC table in preparation for the fixed transmission power of the base station, an error occurs in the initial transmission. However, since the default value of the DRC table is a value set for a sufficiently low target error rate, the overall cell throughput is improved even if an initial transmission error occurs to some extent.

Then, the base station transmits the determined DRAI value to the terminal in accordance with service or user-specific transmission requirements.

Then, after receiving the DRAI, the UE adjusts DRC values preset in the following DRC table according to the received DRAI value. The reception operation of the UE will be described with reference to the accompanying drawings.

3 is a flowchart illustrating an operation of receiving a DRAI in a terminal according to an embodiment of the present invention.

When the UE receives the DRAI in step 300, it is checked whether the sign bit of the DataRateAdjustmentInformation field is '0' in step 310. In step 320, when the sign bit is '0', the boundary value of the DRC table is increased by the Delta bit. After that, the process proceeds to step 300 and waits for reception of a new DRAI. The actual DRC value is determined according to each step of FIG. 5A, and the terminal determines the DRC value according to the reception strength (C / I: Carrier to Interference or Epilot / Nt) of the pilot power transmitted by the base station. On the other hand, if the sign bit is not '0' in step 310, the threshold value of the DRC table is reduced by Delta bits in step 330, and then step 300 is performed.

Accordingly, the base station receives the DRC value and schedules the terminal, and uses the data rate and the transmission slot corresponding to the DRC value transmitted by the terminal for the scheduled terminal. This operation is described in more detail with reference to FIG. 4, which shows an example of the DRC table as follows. The DRC table is not predetermined, and other values may be used according to implementation.

4 is a diagram illustrating an example in which a DRC table changes according to DRAI reception according to an embodiment of the present invention.

The DRC value is preset in accordance with the reception strength (C / I) of the pilot received from the base station. For example, if the reception strength of the pilot received from the base station is -9.25 dB, the terminal transmits a DRC value of 0x5 to the base station. And if the strength of the pilot of the base station received from the base station is 1.25dB, the terminal transmits a DRC value of 0xC to the base station. Then, the base station receives the DRC value, schedules the terminal, and transmits data using the data rate and the transmission slot corresponding to the DRC value being transmitted for the scheduled terminal.

The DRC value of the DRC table is adjusted to a value within a range set by the base station, that is, a DRAI value. For example, if the DRAI value is '00010100' and the correction is made in 0.025dB unit as illustrated above, the sign bit is 0, which means upward adjustment of the threshold value, and the Delta bit is '0010100', so the value of 0.5dB DRAI value '00010100' means + 0.5dB. In this case, adjust the pilot reception strength range used in the table by 0.5 dB. As described above, an example of changing the table by receiving a DRAI value ('00010100') in the table in which the reception strength range is adjusted is as follows.

If the reception strength of the pilot received from the base station before the terminal receives the DRAI value ('00010100') is -9.25 dB, the terminal transmits a DRC value of 0x5 to the base station. However, after receiving the DRAI value ('00010100'), the DRC value of 0x4 is transmitted to the base station in the DRC table adjusted up by 0.5 dB. Therefore, although the base station receives the pilot of the same size according to the DRAI value transmission, the base station transmits different DRC values and schedules them with different data rates and transmission slots, thereby enabling modification of transmission characteristics according to the type of user or service. do. The change in the range of the DRC table indicating the pilot reception reception strength for determining the DRC value may be limited to a maximum and minimum possible range, which may be fixed when the terminal is implemented, and the base station and the terminal transmit signal signals. It can then be received and negotiated or specified.

In an embodiment of the present invention as described above, a method of controlling a transmission rate by adjusting a DRC table by transmitting a DRAI to a terminal according to a rate change factor has been described, but in another embodiment of the present invention, a packet transmitted from a terminal A rate control method for adjusting a DRC table by transmitting a target error rate of forward transmission from a base station to terminals according to data transmission information (ACK, NAK) or type of service and requirements will be described.

The channel condition received by the terminal is dynamically changed according to factors such as interference and mobility around. In this situation, if the same DRC value is always reported for the same pilot reception strength, the reception error rate continuously changes according to the channel change. To compensate for this, the 1x-EVDO terminal currently uses the transmission error rate set at the time of manufacture of the terminal. To ensure that the DRC decision table is constantly changing. That is, if the error rate of the forward transmission is lower than the target error rate, the boundary value of the DRC table is decreased little by little, requiring a higher transmission rate for the same pilot reception strength. On the contrary, if the transmission error rate is higher than the target error rate, the boundary value of the DRC table is decreased. Increasingly, lower transmission rates are required for the same pilot reception strength. This operation is similar to the outer loop power control used in the voice transmission of the conventional CDMA system, and is a process for guaranteeing a predetermined error rate regardless of channel conditions.

The base station continuously accumulates statistics on ACK or NAK transmitted by the terminals and changes the DRC table of the terminals based on the statistics. However, the base station cannot know how much the quantitative DRC table change value transmitted by the base station affects the actual terminal. That is, the DRC table is transmitted by the base station, but the subject that determines the DRC is the terminal, and the reception channel situation (receive pilot strength) for each terminal varies in accordance with the location, movement, and moving speed of each terminal, and is common to all terminals. Since the DRC change information cannot be applied, the base station cannot know how much the transmission error rate of the terminal will change. Therefore, the base station should transmit a transmission target FER of the forward transmission to the terminal. A method of transmitting such a forward target error rate is described below.

The base station transmits the target error rate of the forward transmission, not the DRC table itself, to the terminal, and the terminal adjusts the DRC table according to the target error rate of the received forward transmission to change the DRC table to suit the corresponding error rate. For example, when the base station transmits a target error rate of 5% when the current terminal determines a DRC with a target error rate of 1%, the terminal gradually changes the DRC table. That is, if the transmission using the DRC table is normal, the boundary value of the DRC table is reduced by (0.5 / 95) dB, and when the transmission error occurs, the boundary value of the DRC table is increased by (0.5 / 5) dB. This method is similar to the outer loop power control used for voice transmission in the conventional CDMA system.

The base station defines a forward target error rate message in the form of a forward traffic channel MAC protocol message to transmit the target error rate of the forward transmission. A structure of such a forward link target frame error rate message (FLTFERM) will be described with reference to Table 7 below.

In Table 7, the MessageID field of the forward target error rate message has an 8-bit identifier value as a message identifier field. The FLTFERMessageSequence field is an 8-bit long field representing sequence information between various forward target error rate messages transmitted. The FLTFERMessageSequence field is incremented by 1 for each transmission by the base station. The ForwardLinkTargetFER field is a 4-bit field representing the value of the forward target error rate. The information represented by the 4 bits may vary depending on the implementation. An example of the ForwardLinkTargetFER is shown in Table 8 below.                     

In Table 7, the forward target error rate message is individually transmitted for each broadcast type message or terminal through the forward control channel. The terminal changes the boundary value of the DRC table to suit the forward target error rate transmitted through the forward target error rate message. In addition, a DRC suitable for the strength of the pilot signal received through the physical layer is determined. In this case, the terminal declares the target error rate as public data so as to use the target error rate information received by the MAC protocol so that the physical layer protocol can use the error rate. The target error rate disclosure data is set to an appropriate initial value in advance in implementation.

As described above, in addition to the method of transmitting the forward target error rate to the terminal using the forward target error rate message, the forward target error rate may be defined and transmitted by defining a configuration attribute of the forward traffic channel MAC protocol. The forward target error rate setting speed structure is described in Table 9 below.                     

In Table 9, the Length field has a value indicating the length of the record except for the Length field in octets. The AttributeID field has a value promised as the FLTFER attribute, and the value of the ForwardLinkTargetFER field has a 4-bit length value as shown in Table 10 below, and may have a specific initial value depending on the implementation.

These configuration attributes are defined as public data of the corresponding protocol to form a DRC table suitable for the configuration attributes negotiated at the physical layer that sets and transmits the actual DRC value.

When the target error rate transmission method of the forward transmission is used, the terminal must vary the adjustment value of the table according to the received target error rate. For example, if you use the target error rate of 1%, the boundary value of the DRC table is reduced by (0.5 / 99) dB for each normal data frame received, and the error in the DRC table for each error occurred in the received data frame. Increasing the threshold by 0.5dB ensures transmission performance that always converges to a target error rate of 1%. If you use the target error rate of 5%, you can satisfy the 5% error rate by using (0.5 / 95) dB decrease or (0.5 / 5) dB increase or decrease of the threshold value of the DRC table, unlike 1% error rate. . The operation of the physical layer protocol of the terminal in connection with such DRC table adjustment will be described with reference to the drawings.

5 is a flowchart illustrating an operation for maintaining a forward target error rate at a transmitting side of a terminal according to another embodiment of the present invention. Herein, the variable represented by "x" is a variable that stores the current target error rate. For example, in the case of 1%, the variable stores a value of 0.01.

As shown in FIG. 5, the terminal determines whether the frame currently received in step 510 is data transmitted to the terminal. As a result of the check, if the data is not transmitted to the user, the operation is terminated. Here, the terminal receives a first slot of a data frame transmitted to the terminal using a Walsh cover corresponding to the MAC index assigned to the terminal. In this case, if the transmitted data is retransmission data, the terminal combines the current reception frame with the previous reception frame in step 525 and proceeds to step 530. On the other hand, if the retransmission data is not determined whether an error occurs in step 530. In this case, if an error occurs, in step 531, the UE increases the DRC table boundary currently used by as much as the result value (dB) of Equation 1 below.

 In step 1132, the DRC table is readjusted according to the range of allowable DRC table boundary values. That is, if the maximum value of the increased boundary values is larger than the allowable range, the DRC table is newly configured such that the maximum value of the allowable range becomes the maximum boundary value of the adjusted DRC table. Thereafter, in step 533, the terminal transmits a NAK to the base station and ends the operation corresponding to the slot T.

On the other hand, if the error does not occur in step 530, the UE reduces the DRC table boundary value by the result value (dB) of Equation 2 in step 541.

을 목표 오류율로 전송하는 경우 한번 오류가 발생하면 DRC 테이블의 경계 값에 5000dB을 더하게 되어 비현실적인 DRC 테이블을 사용하게 되므로 이런 경우를 방지하고자 허용 가능 범위와 비교하여 테이블을 새로 조절한다. 상기 <수학식 1> 및 상기 <수학식 2>를 통해 구한 경계 값 조정치는 본 발명의 다른 실시 예에서 구체적인 이해를 위해 사용한 값일 뿐이며 실제 구현에 따라 다양한 조정 값들이 사용될 수 있다.In step 1142, the DRC table is readjusted according to the range of allowable DRC table boundary values. That is, if the minimum value of the reduced boundary value is smaller than the allowable range, the DRC table is newly configured such that the minimum value of the allowable range becomes the minimum boundary value of the adjusted DRC table. Then, in step 1143, the UE transmits the data frame to the upper layer. In step 1144, the ACK is transmitted to the base station, and the operation corresponding to the slot T ends. For example, in steps 1132 and 1142, for example, the terminal

In case of sending error at target error rate, if error occurs once, 5000dB is added to the DRC table boundary value and unrealistic DRC table is used. The boundary value adjustment values obtained through Equation 1 and Equation 2 are just values used for specific understanding in other embodiments of the present invention, and various adjustment values may be used according to actual implementation.

The operation of the terminal for maintaining the forward target error rate and the operation of transmitting the DRC adjusted according to the operation of the terminal when receiving the DRAI of FIG. 3 will be described with reference to the drawings.

6 is a flowchart illustrating an operation of transmitting a DRC in a terminal according to an embodiment of the present invention. Here, the public data "DRCGating" is a variable indicating the transmission mode of the DRC, "FrameOffset" is a variable indicating the reverse transmission time compared to the PN 0-offset, "DRCLength" stores how many slots to send one DRC value divided into Variable, where "T" represents the current slot number.

As shown in FIG. 6, in step 1000, the UE determines whether the current state is the DRC gating mode, that is, the public data DRCGating is 1. As a result of determination, if the current state is DRC gating mode, the UE checks whether it is time to transmit the DRC value in step 1005, that is, the (T + 2-frame offset) mod DRC length is zero. As a result of the check, if the terminal is not 0, the terminal proceeds to 1000 without transmitting the DRC value and performs an operation for determining the DRC value of the next slot T + 1. If the terminal is 0, the terminal proceeds to step 1020.

On the other hand, if the DRC gating is not 1 in step 1000, the UE checks whether the (T + 1-frame offset) mod DRC length is 0 in step 1010. That is, it is determined whether to update the DRC value. As a result, if it is not 0, the process proceeds to step 1040, and if it is 0, the UE inquires a new DRC value corresponding to the average pilot reception strength received in step 1020 in the DRC table, and in step 1030 the DRC value is inquired. Change to the new DRC value. Then, in step 1040, the DRC value is transmitted to the base station. In step 1000, the DRC transmission operation is performed during the next slot (T + 1).

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, in the present invention, the base station may determine a data rate control value of a desired degree and reflect it in the forward data rate, and may consider the transmission characteristics (QoS parameters) required for each service or user. In addition, since the target error rate is transmitted to the terminal, the desired error rate can be set and maintained differently for each terminal, thereby improving the performance of the overall system.

Claims (29)

A method for controlling a forward data rate in a base station of a mobile communication system transmitting packet data to a terminal having a best reception state among a plurality of terminals, Generating data rate adjustment information simultaneously applied to the terminals according to a rate change factor for changing the forward data rate, and transmitting the generated data rate adjustment information to the terminals; Receiving a data rate control value corresponding to a pilot reception strength range adjusted by the data rate adjustment information from the terminals; And transmitting the packet data to a terminal having the best reception state according to a transmission rate corresponding to the received data transmission rate control value. The method of claim 1, And transmitting the generated data rate adjustment information through a forward control channel using a broadcast message. The method of claim 1, The rate change factor is information regarding the interference between the base station and other base stations, the amount of traffic in the base station and base station control period, and the inter-sector interference in the base station as the state information of the base station. A method of controlling a forward data rate in a base station of a mobile communication system transmitting packet data to a terminal having a best reception state among a plurality of terminals, Generating data rate adjustment information applied to each terminal according to the rate change factor and transmitting the generated data rate adjustment information to the respective terminals; Receiving a data rate control value corresponding to a pilot reception strength range adjusted by the data rate adjustment information from the terminals; And transmitting the packet data to a terminal having the best reception state according to a transmission rate corresponding to the received data transmission rate control value. The method of claim 4, wherein And transmitting the generated data rate adjustment information through a forward control channel using a unicast message. The method of claim 4, wherein And transmitting the generated data rate adjustment information through a forward traffic channel using a unicast message. The method of claim 4, And transmitting the generated data rate adjustment information through a forward traffic channel using a medium access control layer protocol configuration attribute. The method of claim 7, wherein The data rate adjustment information is defined as a value of the session configuration information stored for each terminal. The method of claim 4, wherein The rate change factor is the rate control method, characterized in that the information on the status information of the base station, the situation for each terminal, the type of service for each terminal and the quality of service required for each terminal. In the method for controlling the forward data rate in the terminal of the mobile communication system for transmitting packet data to the terminal having the best reception state among the plurality of terminals, Receiving a data rate control table including data rate control values set corresponding to a range of pilot reception intensity of the base station and data rate adjustment information generated according to a rate change factor from the base station; Adjusting the range of the pilot reception strength of the data rate control table by applying the received data rate adjustment information, and determining a data rate control value corresponding to the pilot reception intensity currently measured in the adjusted data rate control table; Process, And transmitting the determined data rate control value to the base station. The method of claim 10, And receiving the data rate adjustment information through a forward control channel using a broadcast service. The method of claim 10, And receiving the data rate adjustment information through a forward control channel using a unicast message. The method of claim 10, And receiving the data rate adjustment information through a forward traffic channel using a medium access control layer protocol configuration attribute. The method of claim 13, The data rate adjustment information is defined as a value of the session configuration information stored for each terminal. The method of claim 10, The rate change factor is the rate control method, characterized in that the information on the status information of the base station, the situation for each terminal, the type of service for each terminal and the quality of service required for each terminal. A method for controlling a forward data rate in a base station of a mobile communication system transmitting packet data to a terminal having a best reception state among a plurality of terminals, Determining a target error rate of forward transmission applied to the terminals according to the packet data transmission information transmitted from the terminals and transmitting the target error rate to the terminals; Receiving a data rate control value corresponding to a pilot reception strength range adjusted by a target error rate of the forward transmission from the terminals; And transmitting the packet data to a terminal having the best reception state according to a transmission rate corresponding to the received transmission rate control value. The method of claim 16, And transmitting the determined target error rate of the forward transmission to the terminals simultaneously through a forward control channel using a forward target error rate message. The method of claim 16, And transmitting the determined target error rate of the forward transmission by using a forward target error rate message for each terminal through a forward traffic channel. The method of claim 16, And transmitting the determined target error rate of the forward transmission by the terminal through a forward control channel using a forward target error rate message. The method of claim 16, And transmitting the determined target error rate of the forward transmission is transmitted through a forward traffic channel using a medium access control layer protocol configuration attribute. The method of claim 16, The packet data transmission information indicates a reception situation for each terminal of the packet data received from the base station, a service type for each terminal, a service quality required for each terminal, and the like. In the method for controlling the forward data rate in the terminal of the mobile communication system for transmitting packet data to the terminal having the best reception state among the plurality of terminals, Receiving a target error rate of forward transmission determined according to packet data transmission information from a base station; Adjusting a data rate control table by applying a target error rate of the received forward transmission; Determining a data rate control value corresponding to the pilot reception intensity currently measured in the adjusted data rate control table; And transmitting the determined data rate control value to the base station. The method of claim 22, The packet data transmission information indicates a reception situation for each terminal, a service type for each terminal, and a quality of service required for each terminal, for the packet data received from the terminal to the base station. The method of claim 22, And receiving the determined target error rate of forward transmission through a forward control channel using a forward target error rate message. The method of claim 22, And the receiving of the determined target error rate of forward transmission is received through a forward traffic channel using a forward target error rate message. The method of claim 22, And receiving the determined target error rate of forward transmission is received through a forward traffic channel using a medium access layer protocol setting attribute. The method of claim 22, wherein adjusting the data rate control table comprises: Querying the data rate control table and transmitting a data rate control value determined according to a target error rate of the received forward rate; Confirming whether packet data is received from the base station according to the determined data rate control value; Checking whether the received packet data is packet data transmitted to the packet data when the packet data is received; Adjusting a boundary value of the data rate control table according to whether or not an error of the received packet data occurs in the case of packet data transmitted to itself; And re-adjusting the adjusted data rate control table within a preset allowable range. The method of claim 27, And adjusting the threshold value of the data rate control table to reduce the threshold value of the data rate control table when the packet data is normally received. The method of claim 27, And adjusting the threshold value of the data rate control table to increase the threshold value of the data rate control table when an error occurs in the received packet data.

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