KR20050006642A - Outer loop power control method at packet non-transmission period in packet communication system - Google Patents

Abstract

PURPOSE: A method for controlling an outer loop power of a packet non-transmission interval in a packet communication system is provided to stably perform an outer loop power control in coping with a quick fading. CONSTITUTION: Data packets and data rate indication information for indicating a transmission rate of the data packets are transmitted to a base station. When there is no more data to be transmitted, the first null data rate information is continuously transmitted during a certain time interval in order to inform the base station about entering a packet non-transmission interval. After the first null data rate information is transmitted, the following null data rate information is periodically transmitted so that the base station can control outer loop power of the packet non-transmission interval.

Description

Outer Packet Power Control Method for Out-of-Transit Section in Packet Communication System {OUTER LOOP POWER CONTROL METHOD AT PACKET NON-TRANSMISSION PERIOD IN PACKET COMMUNICATION SYSTEM}

The present invention relates to a wireless packet mobile communication system supporting a multimedia service, and more particularly, to a method for performing outer loop power control of a packet non-transmission interval on a reverse link from a terminal to a base station.

In general, a code division multiple access (CDMA) mobile communication system is a third generation CDMA (hereinafter referred to as CDMA 2000) capable of transmitting not only voice but also high-speed data. It is said to have developed. Since the third generation CDMA mobile communication system can support a transmission rate of up to 2 Mbps (mega bit per second), it can be compared to the second generation CDMA mobile communication system supporting a transmission rate of about 9.6 kbps (kilo bit per second) or 14.4 kbps. You can transfer as much as 256 times as much data. Therefore, various multimedia services such as high quality voice, moving picture, and internet search are possible through this data transmission capability.

A large amount of data is divided into packets having a predetermined size and transmitted through wireless and wired sections. The transmission of packet data has a characteristic of discontinuous transmission (DTX) due to the nature of multimedia service, which means that a section in which a packet is transmitted and a packet non-transmission section in which a packet is not transmitted occur alternately at an arbitrary time. .

In order to increase the throughput of the reverse link in a wireless packet mobile communication system supporting multimedia services, it is essential to use a hybrid automatic repeat request (H-ARQ) technology. In this case, the H-ARQ indicates an acknowledgment (ACK) or a negative acknowledgment (NAK) indicating whether the physical layer packet is successfully received through the response channel of the forward link with respect to the physical layer packet transmitted from the UE. To transmit. The terminal receiving the acknowledgment transmits a new packet, and the terminal receiving the acknowledgment retransmits the previously transmitted packet. The base station may attempt to decode in combination with the same packet previously received for the retransmitted packet, thereby increasing the probability of success of the packet. In H-ARQ, the number of retransmissions is limited to three times. This means that up to two retransmissions are possible if the initial transmission fails.

On the other hand, power control to determine the transmission power of the terminal is divided into inner loop (power) loop control and outer loop (outer loop) power control. Internal cyclic power control is a power that allows the base station to adjust the transmit power by transmitting a power up / down command to the terminal by comparing the power level received from the terminal to a power control set point. Means control. Outer loop power control is to change the reference point for the inner circulation power control according to the channel environment, such as Doppler, fading, etc., it is possible to properly maintain the quality of the frame. In order to set the frame error probability to 1%, an external power control may be used to set an appropriate power control reference point according to the channel environment.

In the case of using the H-ARQ, the external cyclic power control in the packet transmission interval is performed according to the successful reception of data. That is, each time the H-ARQ physical layer packet is successfully received, the reference point is reduced by a predetermined value, for example, (1/99) dB, and the reference point is received after the packet reception fails even after receiving the maximum number of retransmissions. Is increased by a predetermined value, for example 1 dB. At this time, before the maximum number of retransmissions is reached, the reference point is not adjusted even if the packet fails to be received. This is because the external cyclic power control aims to set the final residual packet error probability to 1%.

However, since no data is transmitted in the packet non-transmission period, external cyclic power control using the data packet is impossible. The base station does not know how long the packet non-transmission period lasts. Since the channel environment may be changed during the packet non-transmission period, if the external circulation power control is not performed in the packet non-transmission period, it may be impossible to allocate proper power to the packet transmission at the time when the packet starts to be transmitted. Using too much or too little power for packet transmission reduces data throughput by reducing the probability of successful packet transmission.

In the known conventional technology, external cyclic power control is performed by using information of a control channel transmitted at predetermined time intervals in a packet non-transmission interval. In detail, when the UE is in a packet non-transmission interval, the UE may transmit information indicating a null data rate at a predetermined period at a time agreed with the base station by the system time, and includes a reverse link-rate indication channel (R). -RICH). R-RICH is used to indicate the reverse data rate of the packet in the packet transmission interval, but is used to indicate the null data rate in the non-packet transmission interval.

The base station lowers the power control reference point by a predetermined value upon successful reception of the information indicating the null data rate at the promised time. On the other hand, if the reception of the information indicating the null data rate fails, i.e., the information indicating the data rate is received or the received energy of the R-RICH is lost because it does not reach the detection threshold, the base station sets the power control reference point by a predetermined value. Up.

The external cyclic power control according to the prior art is suitable to be applied when the packet length is relatively long, and shows a deterioration in performance when the packet length is short. For example, if the data packet length is 5ms, the length of the information transmitted through the R-RICH is also 5ms. Short length of information is likely to succeed or fail due to fast fading such as Rayleigh fading in the radio section. External cyclic power control should be designed to keep up with the long term change of channel environment such as Doppler. If the reference point is adjusted according to fast fading, power control is not stable. Therefore, when the external communication power control is performed using the null data rate during the packet non-transmission period in the packet communication system, the error probability of the R-RICH is determined by fast fading, so that the external circulation power control is adapted to the channel characteristics different from the packet transmission period. There is a need for a way to prevent it.

In addition, since it is difficult for the base station to immediately recognize that the terminal enters the packet non-transmission period, it is difficult to determine whether the terminal does not transmit data or whether data is lost due to an error during transmission. In this case, although the base station is a packet non-transmission period, there was a problem that the external cyclic power control of the packet non-transmission period could not be performed immediately.

Accordingly, the present invention, which was devised to solve the problems of the prior art operating as described above, provides a method for performing external cyclic power control of a packet non-transmission interval in a packet communication system using complex automatic retransmission.

The present invention provides a method of continuously and repeatedly transmitting null data rate information in such a manner that external cycle power control of a packet non-transmission interval can be performed in a packet non-transmission interval.

The present invention provides a method of transmitting null data rate information having a length longer than the data rate indication information of the packet transmission interval so that the external cyclic power control can be performed in the packet nontransmission interval.

The present invention provides a method of performing external cyclic power control by combining a plurality of data rate indication information to determine whether a packet is not transmitted.

In one embodiment of the present invention, in a packet communication system, a method for performing external cyclic power control of a packet non-transmission interval by a terminal,

Transmitting data packets and data rate indication information indicating a data rate of the data packets to a base station;

Continuously transmitting first null data rate information having a length equal to the data rate indication information for a predetermined time period to notify the base station that the base station enters a packet non-transmission period when it is determined that there is no more data to transmit;

And transmitting the subsequent null data rate information periodically so that the base station can perform the external cyclic power control of the packet non-transmission period after transmitting the first null data rate information.

According to another embodiment of the present invention, in a packet communication system, a method for performing external cyclic power control of a packet non-transmission interval by a terminal,

Transmitting data packets and data rate indication information indicating a data rate of the data packets to a base station;

Transmitting first null data rate information having a length longer than the data rate indication information to inform the base station that the base station enters a packet non-transmission period when it is determined that there is no more data to transmit;

After transmitting the first null data rate information, the base station periodically transmits subsequent null data rate information having a length longer than the data rate indication information so that the base station can perform external cyclic power control of the packet non-transmission interval. Characterized in that it comprises a process.

According to another embodiment of the present invention, in a packet communication system, a method for performing external cyclic power control of a packet non-transmission interval by a base station,

Receiving data rate and data rate indication information indicating a transmission rate of the data packets from a terminal and performing external cyclic power control of a packet transmission interval using the data packets;

Checking whether the first null data rate information is continuously received from the terminal for a predetermined time interval;

And when the first null data rate information is continuously received during the predetermined time interval, performing external cyclic power control of the packet non-transmission interval by using the subsequent null data rate information received from the terminal. do.

According to another embodiment of the present invention, in a packet communication system, a method for performing external cyclic power control of a packet non-transmission interval by a base station,

Receiving data rate and data rate indication information indicating a transmission rate of the data packets from a terminal and performing external cyclic power control of a packet transmission interval using the data packets;

Checking whether first null data rate information having a length longer than the data rate indication information is received from the terminal;

And when the first null data rate information having a length longer than the data rate indication information is received, performing external cyclic power control of the packet non-transmission interval using the subsequent null data rate information received from the terminal. It is characterized by.

1 is a view showing a simplified configuration for power control in a packet communication system according to the present invention.

2 is a diagram illustrating an external cyclic power control operation in a packet transmission interval.

3 is a diagram illustrating transmission of data rate indication information in a packet non-transmission interval.

4 is a diagram illustrating transmission of null data rate information in a packet non-transmission period according to an embodiment of the present invention.

5 is a diagram illustrating transmission of null data rate information in a packet non-transmission period according to another embodiment of the present invention.

6 is a diagram illustrating an external cyclic power control operation in a packet non-transmission interval according to the present invention.

7 is a flowchart illustrating the operation of a terminal according to an embodiment of the present invention.

8 is a flowchart illustrating the operation of a base station according to an embodiment of the present invention.

In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

The present invention described below is to perform the external cyclic power control of the packet non-transmission interval in the packet communication system.

1 illustrates a simplified configuration for power control in a packet communication system according to the present invention.

As shown, a mobile station (MS) 10 reverses a reverse rate indicator channel (R-RICH) transmitter 12 that transmits data rate indication information indicating a reverse data rate. Reverse Packet Data Channel (R-PDCH) 14 for transmitting data traffic, including transmitter 14. The base station determines the transmit power of the R-RICH receiver 22 and the terminal 10 receiving the reverse data through the R-PDCH and the R-RICH receiver 22 receiving the data rate indication information through the R-RICH. And a power control processor 26. The determined transmit power is transmitted to the terminal 10 through the forward channel on the power control command.

The power control processor 26 performs external cyclic power control using the data packets received through the R-PDCH in the packet transmission section, and uses the data rate indication information received through the R-RICH in the non-packet transmission period. Perform cyclic power control. Here, the external circulation power control refers to an operation of adjusting a power control set point for internal circulation power control.

2 illustrates an external cyclic power control operation in a packet transmission interval. Here, the maximum number of retransmissions for the same data packet is three times, and the reference point is increased when the reception of the packet is unsuccessful even after three transmissions.

As shown, the terminal transmits reverse data through a reverse packet data channel (R-PDCH) and transmits the reverse data rate through a reverse rate indication channel (R-RICH). Reverse Rate Indicator Information (hereinafter referred to as RRI) is transmitted. In sequence numbers such as '00', '10', and '21' identifying data packets, the first number represents the index of the H-ARQ channel and the second number represents the data packet transmitted through the corresponding H-ARQ channel. Means the number of retransmissions. In each H-ARQ channel, the 0th packet is marked as '00' for initial transmission, '01' for retransmission of the 0th packet, and '02' for the last third transmission of the 0th packet.

Each time the base station successfully receives data packets of the H-ARQ physical layer, the base station decreases the power control reference point by a predetermined value, for example, (1/99) dB, and the last packet according to the maximum number of retransmissions (that is, the third packet). If reception fails, the power control reference point is increased by a predetermined value, for example, 1 dB. The base station does not adjust the power control reference point if it fails to receive a packet other than the last, i.e., if it fails to receive the first packet or the second packet.

When the packet communication system supports the discontinuous transmission mode (DTX), when it is determined that there is no data to be transmitted, the terminal stops transmitting data and enters a packet non-transmission period. Since data is not transmitted in the packet non-transmission period, the base station cannot perform external cyclic power control using the data packet. Accordingly, the terminal continuously transmits data rate indication information through the R-RICH without transmitting data. In the non-packet transmission period, since no data is transmitted, the data rate indication information indicates a null data rate and is thus called null data rate information. The base station performs out-of-water switching power control using null data rate information instead of the data packet in the packet non-transmission period.

3 shows transmission of data rate indication information in a packet non-transmission interval. The data rate indication information transmitted by the terminal through the R-RICH is used for external cyclic power control by the base station.

As shown, the terminal intermittently transmits data rate indication information indicating null data rate, that is, null data rate information, through the R-RICH in the packet non-transmission period. Here, intermittent means that null data rate information is discontinuously transmitted, and a transmission period of null data rate information is indicated as Null_R-RICH_tx_period.

In the packet non-transmission period, the UE transmits null data rate information to the base station at intervals of Null_R-RICH_tx_period starting from User_Specific_Null_R-RICH_offset, which is time information indicated by the base station. The time point information is a value indicating a time offset from when the terminal confirms that there is no more data to transmit to the first null data rate information and reduces interference caused by null data rate information transmitted by other terminals. It is used to make. The null data rate information is transmitted with the same power as the data rate indication information of the packet transmission interval.

However, since the length of the physical layer packet used for transmission through the R-RICH is relatively short, the R-RICH is sensitive to fast fading. In this case, the increase / decrease of the power control reference point may not be performed stably in the packet non-transmission period. Accordingly, the present invention proposes a method for the base station to immediately recognize the non-packet transmission interval and perform external cyclic power control under the same conditions as in the packet transmission interval.

4 illustrates transmission of null data rate information in a packet non-transmission interval according to the present invention. The null data rate information transmitted by the terminal through the R-RICH is used for external cyclic power control by the base station.

As shown, if it is determined that there is no more data to transmit, the terminal enters a packet non-transmission interval and continuously transmits null data rate information for a predetermined interval NoTx_Indication_length. Here, null data rate information is illustrated as being repeatedly transmitted three times. The base station repeatedly receives null data rate information for a predetermined period and detects that the terminal has entered the non-packet transmission period.

The base station can recognize that the terminal has entered the packet non-transmission interval even with only one null data rate information reception. However, if the null data rate information is lost due to an error in the wireless section, the base station determines whether a packet error has occurred. It may be difficult to immediately determine whether the terminal has not transmitted the data packet. Accordingly, the terminal repeatedly transmits null data rate information so that the base station can recognize the start of the packet non-transmission interval more accurately.

After continuously transmitting null data rate information, the UE transmits null data rate information to the base station at intervals of Null_R-RICH_tx_period starting from User_Specific_Null_R-RICH_offset, which is time information indicated by the base station. Here, the null data rate information is transmitted with a power smaller than the data rate indication information of the packet transmission interval, for example, 1/2 of the power or with the same power.

When the base station recognizes that the packet non-transmission period starts, it starts the external cyclic power control of the packet non-transmission period. A detailed description of the external cyclic power control operation of the packet non-transmission interval according to the present invention will be described later.

In FIG. 4, null data rate information of the packet non-transmission interval has the same length L as data rate indication information in the packet transmission interval. In a modified embodiment of the present invention, the null data rate information is transmitted with a length longer than the data rate indication information of the packet transmission interval. Transmission of null data rate information according to this embodiment is illustrated in FIG. 5.

Referring to FIG. 5, in the packet transmission interval, the UE continuously transmits data rate indication information having a predetermined length L1 through the R-RICH. Upon entering the packet non-transmission interval, the UE continuously transmits null data rate information having a length of L2 greater than L1 over a predetermined period through R-RICH, and then periodically transmits null data rate information having a length of L2. To send. Wherein L2 is for example twice the L1. Similarly, null data rate information having a length of L2 is transmitted with less power, for example, 1/2 power than data rate indication information having a length of L1.

Although FIG. 5 illustrates an operation of repeatedly transmitting null data rate information having a length of L2 at the start of a packet non-transmission interval, if L2 is large enough, the first null data rate information may be transmitted only once. This is because the longer the length of the null data rate information, the less the influence of fast fading during transmission, and therefore, it is easier for the base station to detect the null data rate information.

Likewise, the base station combines and receives the information received through the R-RICH, and if the reception result is null, recognizes that the base station enters the packet non-transmission interval. When the base station recognizes that the packet non-transmission period starts, it determines whether the reception is successful by combining the null data rate information periodically received thereafter, and performs external cyclic power control according to the result.

6 illustrates an external cyclic power control operation in a packet non-transmission interval according to the present invention. Here, the maximum number of times of reception of null data rate information is three times, and the reference point is increased when the reception of null data rate information is not successful until the maximum number of times of reception is reached.

As shown, the terminal periodically transmits null data rate information through the R-RICH. Each time the base station receives null data rate information, it checks whether there is null data rate information that failed to be received previously, and if present, combines the previously failed null data rate information with the currently received null data rate information. Determine whether the information is successfully received.

Specifically, the base station determines whether the reception is successful by combining the null data rate information previously failed to receive and the second null data rate information even after receiving the second null data rate information after the failure of the first null data rate information. . Here, the base station may determine whether the currently received null data rate information is successfully received by combining one or more null data rate information previously failed to receive with the currently received null data rate information.

If the base station fails to receive the first and second null data rate information, the base station maintains the power control reference point. Increase by 1 dB. Upon successful reception of null data rate information, the power control reference point is reduced by a predetermined value, for example (1/99) dB.

Herein, the case where the maximum number of receptions is 3 has been described, but as mentioned above, even when the maximum number of receptions is 2, 4, or more, the base station sets a power control reference point when the second, fourth, or more reception failures occur. Is increased.

7 is a flowchart illustrating the operation of a terminal according to the present invention.

Referring to FIG. 7, in step 100, the terminal transmits reverse data packets together with data rate indication information. The data rate indication information indicates a transmission rate of reverse data packets transmitted in the same time interval. If there is no more data to transmit in step 110, in step 120, the terminal repeatedly transmits null data rate information for a predetermined time period or data rate indication information to inform the base station that it enters the packet non-transmission interval. Null data rate information with a longer length is transmitted. In another case, the terminal may continuously transmit null data rate information having a longer length for a predetermined time interval. The time interval is specified by the base station at call setup.

In step 130, the UE periodically transmits null data rate information with less power than data rate indication information. When reverse data to be transmitted is generated in step 140, the terminal stops transmitting null data rate information and returns to step 100.

8 is a flowchart illustrating the operation of a base station according to an embodiment of the present invention.

Referring to FIG. 8, the base station receives data rate indication information and data packets from the terminal in step 200 and performs external cyclic power control using the data packets in step 210. That is, when the base station successfully receives the data packet, the base station decreases the power control reference point by a predetermined value. On the other hand, if it fails to receive the data packet, the number of receptions is counted and it is checked whether the counted reception count reaches the maximum number of retransmissions. If the maximum number of retransmissions is reached, the power control reference point is increased by a predetermined value.

In step 220, the base station determines whether a packet non-transmission interval is detected. In more detail, when the base station receives null data rate information continuously for a predetermined period from the terminal, the base station determines that a non-packet transmission period is detected. In other cases, when the base station receives null data rate information having a length twice as large as the data rate indication information, the base station determines that a packet non-transmission interval has been detected. If the packet non-transmission interval is not detected, the process returns to step 200 and if detected, the process proceeds to step 230.

In step 230, the base station performs external cyclic power control using null data rate information received from the terminal. That is, when the base station successfully receives null data rate information, the base station decreases the power control reference point by a predetermined value. On the other hand, if it fails to receive the null data rate information, the number of receptions is counted and it is checked whether the counted reception count reaches the maximum reception count. If the maximum number of receptions has been reached, the base station increases the power control reference point by a predetermined value.

If it is determined in step 240 that the packet non-transmission interval has ended, the base station returns to step 200. The end of the packet non-transmission period is determined by receiving data rate indication information from the terminal or receiving a packet data channel signal of a predetermined threshold value or more.

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 those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention enables accurate and efficient external circulation power control under the same conditions as in the packet transmission period in the non-packet transmission period. In particular, it is possible to perform stable external circulation power control in response to fast fading.

Claims (14)

In a packet communication system, a method for performing external cyclic power control of a packet non-transmission interval by a terminal, Transmitting data packets and data rate indication information indicating a data rate of the data packets to a base station; Continuously transmitting the first null data rate information for a predetermined time interval to inform the base station that the base station enters a non-transmission period when it is determined that there is no data to be transmitted; And transmitting the subsequent null data rate information periodically so that the base station can perform the external cyclic power control of the packet non-transmission interval by the base station after transmitting the first null data rate information. . 2. The method of claim 1, wherein the first and subsequent null data rate information has a longer length than the data rate indication information. 2. The method of claim 1, wherein the subsequent null data rate information is periodically transmitted with a predetermined period from a predetermined time offset after transmitting the first null data rate information. In a packet communication system, a method for performing external cyclic power control of a packet non-transmission interval by a terminal, Transmitting data packets and data rate indication information indicating a data rate of the data packets to a base station; Transmitting first null data rate information having a length longer than the data rate indication information to inform the base station that the base station enters a packet non-transmission period when it is determined that there is no more data to transmit; After transmitting the first null data rate information, the base station periodically transmits subsequent null data rate information having a length longer than the data rate indication information so that the base station can perform external cyclic power control of the packet non-transmission interval. The method comprising the step of. The method as claimed in claim 4, wherein the first null data rate information is continuously transmitted for a predetermined time interval. 5. The method as claimed in claim 4, wherein the subsequent null data rate information is periodically transmitted with a predetermined period from a predetermined time offset after transmitting the first null data rate information. A method for performing external cyclic power control of a packet non-transmission interval by a base station in a packet communication system, Receiving data rate and data rate indication information indicating a transmission rate of the data packets from a terminal and performing external cyclic power control of a packet transmission interval using the data packets; Checking whether the first null data rate information is continuously received from the terminal for a predetermined time interval; And when the first null data rate information is continuously received during the predetermined time interval, performing external cyclic power control of the packet non-transmission interval by using the subsequent null data rate information received from the terminal. Said method. 8. The method of claim 7, wherein the first and subsequent null data rate information has a longer length than the data rate indication information. The method of claim 7, wherein the performing of the external cyclic power control of the packet non-transmission interval, If the null data rate information is successfully received from the terminal, the reference point for power control is adjusted downward, and if it is not successfully received, the receiving point is counted and compared with a predetermined maximum number of receptions, and the counted number of receptions is determined. And adjusting the reference point for power control when the maximum number of receptions is reached. 10. The method of claim 9, wherein the performing of the external cyclic power control of the packet non-transmission interval, And determining whether the most recently received null data rate information is successfully received by combining a predetermined number of null data rate information received from the terminal. A method for performing external cyclic power control of a packet non-transmission interval by a base station in a packet communication system, Receiving data rate and data rate indication information indicating a transmission rate of the data packets from a terminal and performing external cyclic power control of a packet transmission interval using the data packets; Checking whether first null data rate information having a length longer than the data rate indication information is received from the terminal; And when the null data rate information having a length longer than the data rate indication information is received, performing external cyclic power control of the packet non-transmission interval using the null data rate information received from the terminal. Said method. 12. The method of claim 11, wherein the first null data rate information is continuously received for a predetermined time interval. The method of claim 11, wherein the performing of the external cyclic power control of the packet non-transmission interval, If the null data rate information is successfully received from the terminal, the reference point for power control is adjusted downward, and if it is not successfully received, the receiving point is counted and compared with a predetermined maximum number of receptions, and the counted number of receptions is determined. And adjusting the reference point for power control when the maximum number of receptions has been reached. The method of claim 13, wherein the performing of the external cyclic power control of the packet non-transmission interval, And determining whether the most recently received null data rate information is successfully received by combining a predetermined number of null data rate information received from the terminal.