CN101616477A - Method and device for controlling reverse traffic rate in mobile communication system - Google Patents

Abstract

A data rate for controlling a next reverse packet data frame in a mobile communication system in which a reverse packet data frame is transmitted from a mobile station to a base station on a reverse packet data channel at a data rate selected from a plurality of data rates systems and methods. The mobile station receives reverse control information for a data rate of a reverse packet data frame, and transmits a next reverse packet data frame at a data rate determined from the reverse control information.

Description

Method and device for controlling reverse traffic rate in mobile communication system

This application is a divisional application of an invention patent application with an application date of March 5, 2004, an application number of 200480005988.5, and an invention title of "Method and device for controlling reverse traffic rate in a mobile communication system".

technical field

The present invention generally relates to a mobile communication system, in particular to an interlaced rate control (IRC) method and device for effectively controlling reverse traffic.

Background technique

Generally, in a Code Division Multiple Access (CDMA) mobile communication system, multimedia services are supported using the same frequency band. The mobile station transmits data to the base station at the same time, and the identification of the mobile station is realized through the spreading code uniquely assigned to the mobile station.

The reverse data transmission from the mobile station to the base station is carried out on the reverse packet data channel (reverse packet data channel, R-PDCH) through the physical layer packet (physical layer packet, PLP), and the packet length is fixed. The data rate is variable for each packet and depends on the power of the mobile station sending the response packet, the total amount of data sent, the rate control bits provided from the base station on the forward rate control channel (RCCH) ( rate control bit, RCB) to control the data rate of each packet.

The base station determines the reverse rate of the mobile station by using the Rise over Thermal (RoT) ratio or the load obtained from the signal-to-noise ratio (SNR) of the mobile station in use. Noise ratio is the ratio of total received power to thermal noise. When the RoT is used, the reverse rate of the mobile station is controlled so that the RoT of the corresponding mobile station approaches the reference RoT, and when the RoT is not available, the reverse rate of the mobile station is controlled so that the load of the corresponding mobile station approaches the reference load. That is, the base station determines whether to increase, decrease, or maintain the data rate of each mobile station based on the RoT, the total amount of transmitted data, and the power state of all mobile stations in use. If the rate of the mobile station is effectively controlled, the throughput of the overall system can be increased.

The information for the rate control of the mobile station determined by the base station is sent to the corresponding mobile station in the form of a reverse control bit (RCB). If the RCB value received from the base station is "+1" indicating "rate increase", the mobile station increases the reverse rate in the next transmission interval. If the RCB value is "-1" indicating "rate decrease", the mobile station decreases the reverse rate in the next transmission interval. If the RCB value is '0' indicating 'rate maintain', the mobile station maintains the current reverse rate in the next transmission interval.

In some systems, the base station controls the traffic-to-pilot power ratio (TPR) of the mobile station instead of controlling the data rate of the mobile station. In a conventional mobile communication system, the base station performs power control on the reverse transmission of the mobile station. In the power control process, the mobile station directly controls the power of the pilot channel according to the power control command received from the base station, and controls channels other than the pilot channel according to the TPR having a fixed value. For example, if the TPR is 3dB, this indicates that the power ratio of the traffic channel to the pilot channel transmitted by the mobile station is 2:1. Thus, the mobile station determines the power gain of the traffic channel such that the traffic channel is twice as high in power as the pilot channel.

Even for other types of channels, the gain of the corresponding channel has a fixed value compared with the gain of the pilot channel. In a method of controlling TPR by a base station, in reverse transmission of a plurality of mobile stations controlling the base station by scheduling, the system notifies TPR allowed for each mobile station instead of directly notifying the scheduling result as a data rate. Here, TPR increases according to the increase of data rate. For example, if the data rate is tripled, the power allocated to the traffic channel by the mobile station is approximately tripled, which means doubling the TPR.

In a conventional mobile communication system, the relationship between the data rate of the reverse traffic channel and the TPR is known in advance from information tables to the mobile station and the base station. Thus, in effect, controlling the data rate of the mobile station is equivalent to controlling the TPR of the mobile station. Here, only one method of controlling the data rate of the mobile station by the base station will be described.

FIG. 1 is a flowchart illustrating the operation of determining a reverse rate by a mobile station according to the prior art. The mobile station can support at least 9.6Kbps, 19.2Kbps, 38.4Kbps, 76.8Kbps, 153.6Kbps, 307.2Kbps for R-PDCH, and can gradually increase, decrease or maintain the reverse rate according to the rate control bit (RCB).

Referring to FIG. 1, in step 110, a mobile station receives a rate control bit (RCB) and analyzes the received rate control bit. In step 120, the mobile station determines whether the value of the rate control bit indicates "rate increase". If the value of the rate control bit is "+1" indicating "rate increase", then in step 130, the mobile station sets the rate to be used in the next time interval to a value one step higher than the rate of the current time interval ( or rate), then proceed to step 170.

However, if the value of the rate control bit is not "+1" indicating "rate increase", the mobile station determines in step 140 whether the value of the rate control bit indicates "rate decrease". If it is determined that the value of the rate control bit is "-1" indicating "rate reduction", then in step 150 the mobile station sets the rate to be used in the next time interval to a value that is one step lower than the rate for the current time interval , and then proceed to step 170.

However, if it is determined that the value of the rate control bit is not "-1" indicating "rate down", then in step 160, the mobile station sets the rate to be used in the next time interval to the same value as the rate of the current time interval. In step 170, the mobile station transmits data frames at the next time interval according to the determined rate.

FIG. 2 is a sequence diagram illustrating an operation of determining a reverse rate by a mobile station according to the prior art. The RCB is sent from the base station to the mobile station once for each time interval. The RCB is used to control the reverse rate of the R-PDCH at the next transmission interval of the mobile station.

Referring to FIG. 2, during time interval t0, the mobile station transmits data frames on a packet data channel (PDCH) at a rate of 9.6 Kbps (see 210). In time interval t1, the base station determines whether to increase, decrease, or maintain the data rate of the mobile station in consideration of the RoT, the buffer state, and the power state of the corresponding mobile station, generates an RCB according to the determination result, and transmits the generated RCB to the mobile station ( See 220). The mobile station then receives the RCB, analyzes the RCB, and determines whether to increase, decrease or maintain the rate of the PDCH in the next time interval t2.

However, in this rate control method, the base station cannot effectively perform rate control on its mobile stations due to the delay between the time when the RCB is generated in the base station and the time when the RCB is actually applied in the mobile station.

For example, in the time interval t5, the base station receives data frames with a rate of 153.6Kbps from the mobile station, and in the same time interval, the base station determines to increase the data rate of the mobile station by one from the current rate of 153.6Kbps according to the conditions of other mobile stations. step, generate a corresponding RCB(+), and transmit the generated RCB(+1) to the mobile station. However, actually, since RCB(+) is transmitted at time interval t6, the time interval for actually applying RCB(+) becomes t7. As a result, in the time interval t7, the mobile station sets a rate of 614.4 Kbps, which is one step higher than the rate of 307.2 Kbps in the previous time interval t6.

When several mobile stations transmit reverse data at the same time, the data transmitted by other mobile stations becomes interference to the signal of a specific mobile station. Thus, the base station controls the operation in such a way that none of the rates or all RoT values of data transmitted by the mobile stations in the cell should exceed a certain threshold. In this case, when a base station increases the data rate of a particular mobile station, the base station must decrease the data rate of other base stations. Therefore, the data throughput of a mobile station receiving data service from a particular base station depends on the efficiency of reverse rate control.

However, as shown in FIG. 2, the mobile station determines from the RCB received from the base station whether to increase, decrease or maintain the next data rate compared to the data rate used in the previous time interval. In this case, due to the delay between the time when the RCB is generated in the base station and the time when the RCB is actually applied in the mobile station, reverse rate control cannot be effectively performed, resulting in a decrease in the data throughput of the entire system. deterioration.

Contents of the invention

Accordingly, it is an object of the present invention to provide a method and apparatus for controlling a reverse rate in a mobile communication system while taking into account the time difference between the time when a rate control bit (RCB) is generated by a base station and the time when an RCB is applied by a mobile station. Delay.

Another object of the present invention is to provide a method and apparatus for increasing the throughput of the overall system through efficient reverse rate control.

According to an aspect of the present invention, there is provided a method for controlling the data rate of the next reverse packet data frame in a mobile station system for operating at a data rate selected from a plurality of data rates at The reverse packet data frame is sent from the mobile station to the base station on the reverse packet data channel, the reverse packet data frame is sent by reverse control information sent from the base station to the mobile station on the forward rate control channel, and then the next reverse packet data frame is controlled. To the data rate of the packet data frame, the method includes the steps of: receiving by the mobile station through the reverse control information an increase or decrease information for the data rate of the reverse packet data frame; and after receiving the increase or decrease information , sending a next frame of reverse packet data at a data rate that is increased or decreased from the selected data rate in response to the increase or decrease information.

According to another aspect of the present invention, there is provided a method for controlling the data rate of the next reverse packet data frame in a mobile station system for a data rate selected from a plurality of data rates Send the reverse packet data frame from the mobile station to the base station on the reverse packet data channel, send the reverse packet data frame through the reverse control information sent from the base station to the mobile station on the forward rate control channel, and then control the next the data rate of the reverse packet data frame, the method comprising the steps of: retransmitting the reverse packet data frame according to an acknowledgment from the base station indicating whether the reception of the reverse packet data frame was successful; The reverse control information based on the data rate of the reverse packet data frame receives information about the increase, decrease or maintenance of the reverse packet data frame for retransmission; and after receiving the increase, decrease or maintenance information, in response to the The received increase, decrease or maintain information transmits the next reverse packet data frame at a rate resulting from the selected data rate increase, decrease or hold.

According to another aspect of the present invention, there is provided a method for controlling the data rate of the next reverse packet data frame in a mobile station system for a data rate selected from a plurality of data rates Send the reverse packet data frame from the mobile station to the base station on the reverse packet data channel, send the reverse packet data frame through the reverse control information sent from the base station to the mobile station on the forward rate control channel, and then control the next The data rate of the reverse packet data frame, the method includes the steps of: receiving by the base station a reverse packet data frame sent at the selected data rate; The reverse control information of the data rate of the reverse packet data frame sends increase, decrease or maintain information.

According to another aspect of the present invention, there is provided an apparatus for controlling the data rate of the next reverse packet data frame in a mobile station system for a data rate selected from a plurality of data rates Send the reverse packet data frame from the mobile station to the base station on the reverse packet data channel, send the reverse packet data frame through the reverse control information sent from the base station to the mobile station on the forward rate control channel, and then control the next The data rate of the reverse packet data frame, the device includes: a receiver for receiving from the base station including information on increasing, decreasing or maintaining the data rate of the reverse packet data frame according to whether the reception of the reverse packet data frame is successful the reverse control information; the controller is used to determine the data rate of the next reverse packet data frame according to the received increase, decrease or maintain information based on the selected data rate; and the transmitter is used to determine the data rate of the next reverse packet data frame according to the selected data rate Send the next reverse packet data frame to the base station at the determined data rate.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when combined with the accompanying drawings, in which:

FIG. 1 is a flowchart illustrating the operation of determining a reverse rate by a mobile station according to the prior art;

2 is a sequence diagram illustrating an operation of determining a reverse rate by a mobile station according to the prior art;

3 is a block diagram illustrating an apparatus for controlling a reverse rate according to an embodiment of the present invention;

4 is a flow chart illustrating the operation of determining a reverse rate by a mobile station according to an embodiment of the present invention;

5 is a sequence diagram illustrating an operation of determining a reverse rate by a mobile station for RCD=1 frame (or 1 time interval) according to an embodiment of the present invention;

6 is a timing diagram illustrating an operation of determining a reverse rate by a mobile station for RCD=2 frames (or 2 time intervals) according to an embodiment of the present invention;

7 is a flowchart illustrating the operation of a base station in a system employing HARQ technology and energy reduction (energy reduction) technology according to another embodiment of the present invention;

8 is a sequence diagram illustrating an operation of determining a reverse rate by a mobile station in a system employing a HARQ technique and an energy reduction technique according to another embodiment of the present invention; and

FIG. 9 is a diagram for explaining a method for controlling TPR of each HARQ channel according to an embodiment of the present invention.

Detailed ways

Several preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, detailed descriptions of known functions and configurations incorporated herein are omitted for conciseness.

The present invention is directed to controlling a reverse data rate by using a rate control bit (RCB), wherein a mobile communication system determines a reference time when a base station generates the RCB and a mobile station applies the RCB in consideration of a predetermined delay time. Here, the "delay time" is called "rate control delay (RCD)". RCD-based rate control is also expressed as rate control based on ACID (ARQ (Automatic Repeat reQuest, automatic repeat request) Channel Indicator, ARQ channel indicator). That is, in determining the data rate of the mobile station, the RCB is analyzed on the basis of the rate of packet data corresponding to the preceding ACID, and then the rate of transmitted packet data corresponding to the same ACID is determined.

Also, the method of controlling the data rate of the mobile station is practically equivalent to the method of controlling the TPR of the mobile station. Thus, only the method of controlling the data rate of the mobile station by the base station will be described. However, the method of controlling TPR can also be applied to the rate control method proposed in the present invention.

FIG. 3 is a block diagram illustrating an apparatus for controlling a reverse rate according to an embodiment of the present invention. As shown in Figure 3, the rate control device includes a forward rate control channel (forward rate control channel, F-RCCH) receiver 10, a controller 20, and a reverse packet data channel (reverse packet datachannel, R-PDCH) transmitter 30. For each time interval, the F-RCCH receiver 10 receives the RCB by performing despreading, demodulation, decoding on the signal received from the base station using the spreading code assigned to the F-RCCH, and provides the received RCB to the control device 20.

The controller 20 analyzes the value of RCB to determine whether the base station requires an increase or decrease of the reverse rate, and determines a new reverse rate according to the determination result. Then, the R-PDCH transmitter 30 transmits the data frame according to the determined data rate under the control of the controller 20 . Here, RCB is not a value determined by matching the rate for the next time interval with the rate for the previous time interval, but by matching the rate for the next time interval The value determined by rate matching that has elapsed a predetermined rate control delay (RCD) interval before.

More specifically, assuming that the mobile station transmits one data frame per time interval, the RCD is the delay from when the i-th frame is transmitted when the RCB determined based on the i-th frame is received. The RCD is determined by agreement between the base station and the mobile station when the base station and the mobile station initiate mutual communication. Alternatively, the RCD may be determined by the mobile station. In another case, the RCD may be determined by the base station and then notified to the mobile station. In another case, RCD may be determined in advance between the base station and the mobile station.

Therefore, upon receiving the i-th frame, the base station generates an RCB based on the received i-th frame, and transmits the generated RCB on the R-RCCH. The mobile station receives the RCB, determines the rate of the next frame from the rate of the i-th frame, and transmits the next frame at the determined rate.

As mentioned above, the rate is also controlled based on ACID. Assume that the mobile station sequentially transmits packet data corresponding to ACIDs having values of 00, 01, 10, and 11 at four different time intervals. In this case, assuming that the rate of the current packet data corresponding to ACID=00 is 19.2Kbps and RCB(+) is received, the mobile station can transmit the next packet data corresponding to ACID=00 at 38.4Kbps. That is, in determining the rate at which packet data is currently transmitted, the mobile station determines the rate at which packet data is to be transmitted next based on the rate of previous packet data corresponding to the same ACID.

FIG. 4 is a flowchart illustrating the operation of determining a reverse rate by a mobile station according to an embodiment of the present invention. The mobile station supports at least 9.6Kbps, 19.2Kbps, 38.4Kbps, 76.8Kbps, 153.6Kbps, and 307.2Kbps for R-PDCH, and gradually increases, decreases or maintains the reverse rate according to the rate control bit (RCB).

Referring to FIG. 4, in step 310, the mobile station receives and analyzes a rate control bit (RCB) at an nth time interval. In step 320, the mobile station determines whether the value of the RCB indicates "rate increase". If the value of the rate control bit is "+1" indicating "rate increase", then in step 330 the mobile station sets the rate R(n+1) to be used in the next time interval "n+1" to a rate R(n+1) higher than the occurrence The rate R(n-RCD) for the time interval of the scheduled RCD before the current time interval is incremented by a step value (or rate) and then proceed to step 370 . This can be expressed as shown in Equation 1 below.

R(n+1)=R(n-RCD)++..........(1)

If it is determined in step 320 that the value of RCB is not '+1' indicating 'rate increase', then in step 340 the mobile station determines whether the value of RCB indicates 'rate decrease'. If it is determined that the value of RCB is "-1" indicating "rate drop", then in step 350, the mobile station sets the rate R(n+1) to be used in the next time interval "n+1" to a rate R(n+1) that is less than that occurring in The rate R(n-RCD) of the time interval of the scheduled RCD before the current time interval is decreased by the value of one step, and then proceed to step 370 . This can be expressed as shown in Equation 2 below.

R(n+1)=R(n-RCD)--..........(2)

If it is determined in step 340 that the value of RCB is not "-1" indicating "rate drop", then in step 360, the mobile station sets the rate R(n+1) to be used in the next time interval "n+1" to is the same value as the rate R(n-RCD) for the time interval of the scheduled RCD that occurred before the current time interval. This can be expressed as shown in Equation 3 below.

R(n+1)=R(n-RCD)..........(2)

In step 370, the mobile station transmits data frames in the next time interval "n+1" according to the determined rate R(n+1).

In the present invention, the rate control delay (RCD) is the time required when the mobile station transmits one frame in reverse, taking into account processing delays in the base station and the mobile station. Thereafter, the base station transmits the RCB forward, and the mobile station receives the RCB and applies the received RCB to the data rate of the next frame. RCBs are specified by frames. For example, RCB may be set in one frame or two frames.

5 is a timing diagram illustrating an operation of determining a reverse rate by a mobile station for RCD=1 frame (or 1 time interval) according to an embodiment of the present invention. Referring to FIG. 5, during time interval t0, the mobile station transmits data frames on the PDCH at a rate of 9.6 Kbps (see 410). At time interval t1, the base station determines whether to increase, decrease, or maintain the data rate of the mobile station based on the RoT, buffer state, and power state of the mobile station, generates an RCB according to the determination result, and transmits the generated RCB (see 420).

The RCB is received at the mobile station in time interval t1, and the mobile station determines a data rate to apply in time interval t2 from the received RCB. In determining the data rate to apply in time interval t2, the mobile station is not based on the rate used for the previous time interval t1 but on the rate used for a predetermined RCD or time interval t0 that occurs one frame before the current time interval. rate to determine the data rate. Such rate control is called "interlaced rate control" because rate control is performed separately on odd and even frames as shown in FIG. 5 .

For example, the mobile station uses a rate of 9.6 Kbps during time interval t1. The base station determines a rate at which the mobile station is increased according to state information of the mobile station in time interval t1, generates RCB(+) according to the determination result, and transmits the generated RCB(+) to the mobile station. RCB(+) is received at the mobile station in time interval t2, and based on the received RCB(+), the mobile station sets the rate to be used in time interval t3 to a rate of 19.2Kbps, which is higher than that used for time interval t1 , that is, the rate of the time interval of the RCD occurring before the current time interval increases by one step by 9.6Kbps.

As another example, the mobile station uses a rate of 38.4 Kbps during time interval t5. The base station determines the rate at which the mobile station is increased according to the state information of the mobile station in time interval t5, generates RCB(+) according to the determination result, and transmits the generated RCB(+) to the mobile station. RCB(+) is received at the mobile station in time interval t6, and based on the received RCB(+), the mobile station sets the rate to be used in time interval t7 to a rate of 76.8Kbps, which is higher than that used for time interval t5 , that is, the rate of 38.4Kbps of the time interval of the RCD occurring before the current time interval is increased by one step.

FIG. 6 is a timing diagram illustrating an operation of determining a reverse rate by a mobile station for RCD=2 frames (or 2 time intervals) according to an embodiment of the present invention. Referring to FIG. 6, during time interval t0, the mobile station transmits data frames on the PDCH at a rate of 9.6 Kbps (see 510). At time interval t1, the base station determines whether to increase, decrease, or maintain the data rate of the mobile station based on the RoT, buffer state, and power state of the mobile station, generates an RCB according to the determination result, and transmits the generated RCB (see 520).

The RCB is received at the mobile station in time interval t2, and the mobile station determines a data rate to apply in time interval t3 from the received RCB. In determining the data rate to apply in time interval t3, the mobile station is not based on the rate used for the previous time interval t2 but on the rate used for a predetermined RCD or 2 frames prior to the current time interval t0. rate to determine the data rate.

For example, the mobile station uses a rate of 9.6 Kbps during time interval t1. The base station determines a rate at which the mobile station is increased according to state information of the mobile station in time interval t1, generates RCB(+) according to the determination result, and transmits the generated RCB(+) to the mobile station. RCB(+) is received at the mobile station in time interval t3, and based on the received RCB(+), the mobile station sets the rate to be used in time interval t4 to a rate of 19.2Kbps, which is higher than that used for time interval t1 , that is, the rate of the time interval of the RCD occurring before the current time interval increases by one step by 9.6Kbps.

As another example, the mobile station uses a rate of 38.4 Kbps during time interval t5. The base station determines the rate at which the mobile station is reduced according to the status information of the mobile station in time interval t5, generates RCB(-) according to the determination result, and transmits the generated RCB(-) to the mobile station. RCB(-) is received at the mobile station in time interval t7, and based on the received RCB(-), the mobile station sets the rate to be used in time interval t8 to a rate of 19.2Kbps, which is higher than that used for time interval t5 , that is, the rate 38.4Kbps of the time interval of the RCD occurring before the current time interval is reduced by one step.

In FIG. 5, since RCD=1 frame, rate control is performed separately on two parts (even frame and odd frame). In FIG. 6, since RCD=2 frames, rate control is separately performed on three parts (first frame, second frame, third frame).

In the interleaving rate control method according to the present invention, the mobile station applies information for increasing (+), decreasing (-) or maintaining (0) to the RCB based on the rate used when the base station generates the RCB, so that the base station Inverse rate control errors caused by delays with the mobile station can be eliminated. Thus, by using the staggered rate control method, the mobile station accurately applies the rate calculated during base station scheduling, thereby effectively controlling the reverse rate of the mobile station.

In order to describe the operation of determining the reverse rate of the mobile station by applying the staggered rate control method to the system using the energy reduction technique, it is necessary to first describe the Hybrid Automatic Retransmission Request (HARQ) technique.

HARQ technology is generally used to increase reverse throughput in wireless packet mobile communication systems supporting multimedia services. The HARQ technique is a technique performed on physical layer packets. Hereinafter, an operation of transmitting a frame in the reverse direction using such a HARQ technique will be described.

The base station notifies the mobile station whether the physical layer packet is successfully received through a forward acknowledgment (ACK) channel in response to receiving the physical layer packet from the mobile station. If the physical layer packet is successfully received, the base station sends an ACK signal on the ACK channel indicating successful reception of the physical layer packet. However, if the reception of the physical layer packet fails, the base station transmits a negative acknowledgment (NAK) signal indicating that the reception of the physical layer packet fails on the ACK channel. The mobile station analyzes the signal received on the ACK channel to determine whether the physical layer packet was successfully transmitted. If an ACK signal is received, the mobile station transmits a new packet, and if a NAK signal is received, the mobile station retransmits a previously transmitted packet.

If decoding of a packet previously received from the mobile station fails, the base station combines the retransmitted packet with the previously received packet before attempting to decode, thereby contributing to an increase in the decoding success rate.

In systems using HARQ technology, in order to determine the reverse rate the mobile station uses energy reduction techniques. In the energy reduction technique, when a mobile station attempts retransmission upon receiving a NAK signal from a base station after performing initial transmission in a system using the HARQ technique, the energy of the retransmission packet is set to a value smaller than that of the initially transmitted packet. That is, in this technique, the traffic channel used to retransmit the packet has a lower gain than the initially transmitted packet.

FIG. 7 is a flowchart illustrating operations of a base station in a system employing a HARQ technique and an energy reduction technique according to an embodiment of the present invention. FIG. 8 is a sequence diagram illustrating an operation of determining a reverse rate by a base station in a system employing a HARQ technique and an energy reduction technique according to another embodiment of the present invention. In FIG. 8, the height of the packet data channel represents the channel gain.

7 and 8, if the mobile station transmits packets on the PDCH at time interval t0, in step 700, the base station receives the packets transmitted by the mobile station on the PDCH channel and attempts to demodulate the received packets. In step 710, the base station determines whether the demodulation of the packet was successful. If it is determined that the demodulation is successful, then in step 715, the base station sends an ACK signal on the ACK channel to the mobile station to receive the next packet. At the same time, the base station sends RCB or traffic-to-pilot ratio control bit (TPRCB).

However, if it is determined that the demodulation has failed, then in step 720, the base station transmits a NAK signal 701 to the mobile station on the ACK channel. At this time, the base station does not send RCB 702 because the data rate used for retransmitting packets is not different from the data rate used for initially sending packets and thus TPR control is unnecessary.

Upon receiving the NAK signal 701, the mobile station attempts a retransmission at time interval t2. At this time, as shown in FIG. 8, the energy reduction technique is applied to the packets retransmitted on the PDCH at the time interval t2. Thus, no RCB 702 is received from the base station, and the retransmitted packet is lower in energy than the packet originally sent at time interval t0. The transmission energy of the retransmitted packet can be reduced to 1/2 or 1/4 compared with the transmission energy of the initially transmitted packet.

In step 730, the base station receives the packet retransmitted from the mobile station on the PDCH at time interval t2. In step 740, the base station combines the initial transmission packet received at time interval t0, that is, the packet received at the time interval two RCDs before the current time interval, with the current retransmitted packet and performs demodulation. Thereafter, in step 750, the base station determines whether demodulation is successfully achieved. If it is determined that the demodulation has failed, the base station sends a NAK signal in step 755, and then returns to step 730 to receive a retransmission packet.

For convenience of explanation, in FIG. 7 , when the base station sends a NAK signal in step 755, the base station keeps waiting for retransmission packets. However, in practice, the base station stops retransmission when the number of retransmissions exceeds the predetermined number of retransmissions. Preferably, the predetermined number of retransmissions including the initial transmission is set to 3 or lower.

If it is determined in step 750 that the retransmission packet is successfully demodulated, in step 760, although not shown in FIG. 8, the base station transmits an ACK signal at time interval t2 to inform the mobile station that the packet has been successfully received. At the same time, the base station sends RCB 702 in order to control the rate or TPR of the mobile station.

The operation of controlling the reverse rate or TPR by the mobile station in the system employing the HARQ technique and the energy reduction technique will now be described. It should be noted that this operation is in principle equivalent to the operation in relation to FIGS. 5 and 6 .

Referring back to FIG. 8, once the RCB 702 is received, the mobile station determines whether to increase, decrease or maintain the data rate or TPR according to the command of the RCB 702. The mobile station controls the rate or TPR of packets to be transmitted at time interval t4 based on the information on rate increase/decrease/maintain of packets transmitted at time interval t2. Since the RCD corresponds to two time intervals as shown in FIG. 5 , the mobile station follows the operation described with respect to FIG. 5 . Thus, a detailed description thereof is omitted for brevity. In this case, the operation of controlling the reverse rate by the mobile station is equivalent to that described with respect to FIG. 4 .

However, in an alternative method, the mobile station may control the rate or TPR of packets to be transmitted at time interval t4 based on the increase/drop/remain information for packets transmitted at time interval t0. Here, when the mobile station controls the rate or TPR of the packets to be transmitted at the time interval t4 based on the increase/drop/maintain information for the packets transmitted at the time interval t0, such operation should not violate the Principle of operation of the described embodiment. More specifically, since the energy reduction technique is used, the gains of the respective packet data channels are set to different values, but the packets transmitted by the mobile station at time intervals t0 and t2 have the same rate. Thus, based on the rate of packets sent at time interval t0, the rate at time interval t4 is increased according to RCB(+) 702.

In a system without energy reduction techniques, the mobile station based on the proposed method of the present invention always increases, decreases or maintains the rate of packets sent based on the time interval of RCD that occurred before the current time interval.

Furthermore, although the base station sends TPRCB, the mobile station does not increase, decrease or maintain the current The rate at which packets are to be sent.

A method for transmitting the current packet data frame by using ACID can be expressed as shown in Equation 4 below.

FIG. 9 is a diagram for explaining a method for controlling TPR of each HARQ channel according to an embodiment of the present invention.

In normal HARQ operation, there are several HARQ channels and each HARQ channel is identified with an ARQ Channel Identifier (ARQ Channel Identifier, ACID). For example, if there are 4 HARQ channels, these HARQ channels correspond to ACID=0, ACID=1, ACID=2, ACID=3 respectively, and the HARQ operation is performed independently for each ACID. Although this specification describes the HARQ channel as different channels by separating each ACID, the HARQ channel may be each different frame of one packet data channel.

For better understanding, the operation of a conventional HARQ system using a frame length of 10 ms will be described in detail below.

The mobile station sends an initial transmit packet on a series of HARQ channels starting at a certain start time t=0. That is, at t=0, the mobile station transmits initial transmission packet data on the HARQ channel of ACID=0 which is the first HARQ channel. At t=10 ms, the mobile station transmits initial transmission packet data on the HARQ channel with ACID=1 as the second HARQ channel. At t=20ms, the mobile station transmits initial transmission packet data on the HARQ channel of ACID=2 as the third HARQ channel. At t=30ms, the mobile station transmits initial transmission packet data on the HARQ channel of ACID=3 which is the fourth HARQ channel.

The mobile station receives ACK or NAK from the base station in response to the initial transmission packet transmitted on the HARQ channel of ACID=0, and if the NAK is received, the mobile station performs retransmission through the HARQ channel of ACID=0 at t=40ms. If a NAK is received from the base station in response to the initial transmission packet transmitted on the HARQ channel of ACID=1, the mobile station performs retransmission through the HARQ channel of ACID=1 at t=50 ms.

As described above, a general HARQ operation is performed using several HARQ channels. The interleave rate control method proposed in the present invention is equivalent to controlling the rate of the mobile station or the TPR of the mobile station for each HARQ channel or ACID in the HARQ operation.

Because in HARQ operation, the rate control delay (RCD) is defined by the time period between HARQ channels corresponding to the same ACID, the rate control or TPR for the HARQ channels corresponding to the same ACID is equivalent to the received rate The control bit (RCB) controls the rate at which the time interval of the RCD occurs before the current time interval.

FIG. 9 illustrates a procedure for controlling TPR per HARQ channel or ACID as described above. For example, in FIG. 9, the number of HARQ channels is four. Thus, as shown in FIG. 9, ACID=0, 1, 2, and 3. For convenience of explanation, in the example of FIG. 9 , a response signal such as ACK or NAK for supporting HARQ is omitted. Although an ACK or NAK signal is applied, the rate control operation of FIG. 9 is performed in the same manner except that a retransmission packet is sent in response to a NAK.

In order to perform a TPR control operation for each HARQ channel or ACID, the mobile station may use an internal parameter authorized_tpr as described with respect to FIG. 9 . authorized_tpr refers to a parameter managed by the mobile station to update its maximum TPR value permitted by the base station in order to control its own rate, and it is updated for each ACID. Thus, in this example, authorized_tpr becomes an arrangement (arrangement) of size 4, which is authorized_tpr[4]. Here, authorized_tpr[0] is used for the TPR control of the mobile station of the HARQ channel with ACID=0; authorized_tpr[1] is used for the TPR control of the mobile station of the HARQ channel with ACID=1; authorized_tpr[2] is used for the control of the ACID =2 for the TPR control of the mobile station for the HARQ channel; and authorized_tpr[3] is for the TPR control for the mobile station for the ACID=3 HARQ channel.

In FIG. 9, reference numeral 901 denotes a series of TPRCBs transmitted from the base station to the mobile station, and reference numeral 902 denotes a series of R-PDCHs transmitted in the reverse direction by the mobile station. Also, the numbers 19.2 and 38.4 indicate the data rate in Kbps. In addition, in FIG. 9 , reference numeral 903 denotes an identifier of time lapse in units of 10 ms, and reference numeral 904 denotes ACID which is an identifier of each HARQ channel.

Referring to FIG. 9, operations of the base station and the mobile station will be described in detail.

The mobile station transmits a 19.2Kbps packet on the HARQ channel with ACID=0 at t=t0. At this time, the mobile station sets the value of authorized_tpr[0] to a TPR value corresponding to 19.2Kbps. The mobile station transmits a 38.4Kbps packet on the HARQ channel with ACID=1 at t=t1. At this time, the mobile station sets the value of authorized_tpr[1] to a TPR value corresponding to 38.4Kbps. The mobile station transmits a 38.4Kbps packet on the HARQ channel with ACID=2 at t=t2. At this time, the mobile station sets the value of authorized_tpr[2] to a TPR value corresponding to 38.4Kbps. In addition, the mobile station receives the TPRCB indicating "increase" from the base station at t=t2.

Thus, the mobile station updates the value of authorized_tpr[0] to a TPR value corresponding to 38.4Kbps. Since the mobile station transmits a packet of 19.2 Kbps on the HARQ channel of ACID=0 and then receives a TPRCB indicating "increase" in response thereto, the mobile station increases authorized_tpr[0] corresponding to the same ACID by one step.

The mobile station transmits a 76.8 Kbps packet on the HARQ channel with ACID=3 at t=t3. At this time, the mobile station sets the value of authorized_tpr[3] to a TPR value corresponding to 76.8Kbps.

Furthermore, the mobile station receives a TPRCB indicating "increase" from the base station at t=t3. Thus, the mobile station updates the value of authorized_tpr[1] to a TPR value corresponding to 76.8Kbps. Since the mobile station transmits a 38.4 Kbps packet on the HARQ channel of ACID=1 and then receives a TPRCB indicating "increase" in response thereto, the mobile station increases authorized_tpr[1] corresponding to the same ACID by one step.

In the process of controlling the rate or TPR of packets to be transmitted on the HARQ channel of ACID=0 at t=t4, since the value of authorized_tpr[0] is a value corresponding to 38.4Kbps, the mobile station can transmit packets of 38.4Kbps . In the example of FIG. 9, the mobile station transmits packets of 38.4 Kbps. Such operations are continuously repeated. As described above, the mobile station controls the TPR for each HARQ channel or ACID. Also, as shown in this example, the mobile station can control its own TPR value for each HARQ channel by using the internal parameter authorized_tpr.

There is a currently transmitted packet data frame corresponding to the same ACID among a plurality of previously transmitted packet data frames, and there is a rate of the corresponding packet data frame. As mentioned above, the packet data frame rate can be used in the same expression as TPRCB. Here, the TPRCB permitted by the rate at which the packet data frame was transmitted earlier will be denoted by TPRCB{ACID(P)}, where P stands for "previous".

Additionally, the rate at which the next packet data frame will be transmitted will be denoted by TPRCB{ACID(N)}, where N stands for "next". The mobile station determines whether to increase, decrease or maintain the rate based on control information received from the base station.

The foregoing description can be expressed as shown in Equation 4 below.

TPRCB{ACID(N)}＝TPRCB{ACID(P)}+Delta ..........(4)

That is, the rate of the currently transmitted packet data is increased or decreased by Delta based on the rate of the packet data frame corresponding to the same ACID among the previously transmitted packet data frames. Here "Delta" means a "value" that is increased or decreased based on the control information received from the base station.

As known from the foregoing description, the mobile station applies the RCB based on the rate used when the base station generated the RCB, thereby preventing reverse rate control errors due to processing delays between the base station and the mobile station. Thus, using the interleaving rate control method according to the present invention, the mobile station accurately applies the rate calculated during base station scheduling, thereby effectively controlling the reverse rate of the mobile station.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit of the invention as defined in the appended claims and range.

Claims (11)

1. A method for controlling transmission power of an uplink in a mobile station of a mobile communication system, the method comprising: sending uplink data in a first transmission interval; and receiving transmission power control information via a downlink control channel; determining a transmission power of the uplink data to be sent in the second transmission interval, the transmission power being determined based on the received transmission power control information and the transmission power of the uplink data sent in the first transmission interval, Wherein, the first transmission interval and the second transmission interval are included in the same hybrid automatic repeat request (HARQ) process. 2. The method of claim 1, further comprising transmitting uplink data in a second transmission interval according to the determined transmission power. 3. The method of claim 1, further comprising analyzing received transmit power control information. 4. The method of claim 3, wherein analyzing the received transmission power control information comprises determining whether the received transmission power control information indicates an increase or a decrease in transmission power. 5. The method of claim 1, wherein transmission intervals of the same HARQ process have the same Automatic Repeat Request (ARQ) Channel Indicator (ACID). 6. The method of claim 5, wherein the transmission power of the uplink data to be transmitted in the second transmission interval is determined by TPRCB{ACID(N)}=TPRCB{ACID(P)}+Delta, where TPRCB{ACID(P)}: Traffic-Pilot Ratio Control Bits (TPRCB) corresponding to the transmission power of the uplink data to be sent in the second transmission interval; TPRCB{ACID(N)}: TPRCB corresponding to the transmission power of the uplink data transmitted in the first transmission interval; and Delta: Indicates the value of increasing or decreasing the transmission power according to the transmission power control information. 7. An apparatus for controlling transmission power of an uplink in a mobile station of a mobile communication system, comprising: a receiver for receiving transmit power control information on a downlink control channel; a controller for determining the transmission power of the uplink data to be transmitted based on the received transmission power control information and the transmission power of the uplink data previously transmitted in the same Hybrid Automatic Repeat Request (HARQ) process; and a transmitter for transmitting uplink data according to the transmission power determined by the controller. 8. The apparatus of claim 7, wherein the controller analyzes the received transmission power control information. 9. The apparatus of claim 8, wherein the controller determines whether the received transmission power control information indicates to increase transmission power or to decrease transmission power. 10. The apparatus of claim 7, wherein the uplink data and previously transmitted uplink data include the same automatic repeat request (ARQ) channel indicator (ACID). 11. The apparatus of claim 10, wherein the controller determines the transmission power of the uplink data to be transmitted according to TPRCB{ACID(N)}=TPRCB{ACID(P)}+Delta, where TPRCB{ACID(P)}: Traffic-Pilot Ratio Control Bits (TPRCB) corresponding to the transmission power of the uplink data to be sent in the second transmission interval; TPRCB{ACID(N)}: TPRCB corresponding to the transmission power of the uplink data transmitted in the first transmission interval; and Delta: Indicates the value of increasing or decreasing the transmission power according to the transmission power control information.

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