KR20050088870A - Apparatus and method of forward power control in cdma 2000 system - Google Patents

Abstract

The present invention is to more efficiently control the power of the CDMA 2000 system by adjusting the size of the transmission power of the forward channels of the CDMA 2000 system, and calculates the difference in the transmission power value between the two channels (for example, FCH, DCCH) The present invention proposes a power control apparatus and method for adjusting a transmission power value of a channel in consideration of the calculated difference value.

Description

Apparatus and method for forward power control of CDM2000 system {APPARATUS AND METHOD OF FORWARD POWER CONTROL IN CDMA 2000 SYSTEM}

The present invention relates to power control of a CDMA mobile communication system, and more particularly, to a power control apparatus and method for a forward channel of a CDMA system.

1 is a block diagram of a general mobile communication system.

As shown in FIG. 1, a mobile communication system includes a mobile switching station (MSC) 100, a base station controller (BSC) 110, a base transceiver system (BTS) 120, and The terminal 130 may receive a communication service from them.

Among the mobile communication systems, in particular, the CDMA system requires a power control for optimizing the transmission power of each user since the transmission power of the user acts as an interference to other users. Power control is a technique of adjusting the transmit power of the terminal 130 and the BTS 120 to an appropriate level so that system performance can be maintained even at the lowest possible power level of radiated radio waves. The power control is divided into forward power control and reverse power control. Lose. In FIG. 1, control of transmission power of the BTS 120 is called forward power control, and control of transmission power of the terminal 130 is called reverse power control. In particular, the forward power control is to maximize the forward call capacity in the BTS 120 by minimizing the output of each forward channel according to the position of the mobile station, i.e., the terminal 130, to minimize the RF output of the entire BTS 120. Conventional forward power control generally controls the transmit power value of the forward call channel. However, in a system such as CDMA 2000, the call channel is also divided into several channels, and thus power control for each of the channels is required. A forward channel structure of a CDMA 2000 system is described below with reference to the drawings.

2 is a diagram illustrating a forward channel structure of a CDMA 2000 system.

As shown in FIG. 2, the forward channel of the CDMA 2000 system includes a common assignment channel, a common power control channel, a pilot channel, and a common control channel. It consists of a common control channel, a synchronization channel, a sync channel, a traffic channel, a paging channel, a broadcast channel, and a quick paging channel.

The pilot channels of these channels are the transmit pilot channel, the transmit diversity pilot channel, the auxiliary pilot channel, and the auxiliary transmit diversity pilot channel. Is made of.

In addition, the call channel includes a dedicated control channel (DCCH), a fundamental channel (FCH), a supplemental code channel (SCCH), a power control subchannel (PCS), and an additional channel. (Supplemental Channel, SCH).

On the other hand, in the CDMA 2000 system, a single terminal 130 provides a Concurrent Service, which is a service for simultaneously performing a voice call and a packet call. To this end, the CDMA 2000 system may use each physical channel of FCH, DCCH, and SCH, which are communication channels, in various ways. For example, voice traffic may be transmitted through FCH, signal traffic and data traffic may be transmitted through DCCH, and data traffic may be transmitted through SCH. This is one method of physical channel configuration and can be configured in other ways. As such, power control for each of the FCH, DCCH or SCH becomes very important in the concurrent service implemented using the FCH, DCCH or SCH together.

In particular, when the channel card provided in the BTS 120 processes the FCH and the DCCH, power control becomes more important when the DSP (Digital Signaling Processor) that manages the FCH and the DCCH is divided. When the DSP is divided, the interpretation of the reverse link is different due to the difference in processing time in each DSP, and in each channel element (CE) to which FCH and DCCH are allocated The power control result may vary. For this reason, the DCCH may not be able to apply an appropriate transmit power (tx gain or tx power) value by forward power control. Therefore, there is a case that proper power control for DCCH is not applied among concurrent services that use FCH and DCCH simultaneously.

FIG. 3 is a diagram according to the related art, and illustrates transmission power values of a fundamental channel (FCH) and a dedicated control channel (DCCH) in which power control on a channel is not performed. Is a diagram showing the case where the transmit power value of is lower than the transmit power value of the FCH.

4 is a diagram according to the related art, and illustrates a case where a transmission power value of the DCCH is higher than a transmission power value of the FCH.

3 and 4 compare transmission power values of channels during concurrent services, and in particular, graphs comparing the transmission power values of 1.25 ms units of FCH and DCCH.

3 illustrates an example in which the transmit power value of the FCH is greater than the transmit power value of the DCCH, and since the forward power control for the DCCH is not performed correctly from the terminal 130's point of view, a high FER (Frame Error Rate) occurs for the DCCH. The data transmitted on the DCCH becomes invalid.

4 is a case where the transmit power value of the DCCH is higher than the transmit power value of the FCH in contrast to FIG. 3. 4 is a state in which an output higher than a transmission power value required for forward power control of a DCCH is used, and unnecessary waste of system output occurs, which may act as interference to another terminal 130.

As shown in FIG. 3 and FIG. 4, when the DSP allocated to the FCH and the DSP allocated to the DCCH are different, the transmission power values at each DSP show a considerable difference. In particular, since the DCCH is more sensitive to the radio section than the FCH, when the power control is incorrect, the error rate is higher in the radio section. Therefore, there is a need for efficient power control for stable system implementation.

On the other hand, when performing the forward power control during the Concurrent service based on the FCH, since both the terminal and the system operates based on the information of the FCH, the transmission power value of the DCCH should be changed to be equal to the transmission power value of the FCH. For this purpose, in implementing the Concurrent Service in the CDMA2000 system, it is necessary to synchronize the transmit power values of the FCH and DCCH.

An object of the present invention is to provide a power control apparatus and method capable of power control for each forward channel of a CDMA 2000 system.

Another object of the present invention is to provide a power control apparatus and method that can adjust the transmit power of a dedicated control channel (DCCH) in preparation for the transmit power of a forward basic channel (FCH) of a CDMA 2000 system. have.

It is another object of the present invention to provide a power control apparatus and method for efficient forward power control for DCCH.

Still another object of the present invention is to provide a power control apparatus and method for ensuring stable operation and performance in a concurrent service.

The present invention is to synchronize the transmission power values of a plurality of channels used in implementing a Concurrent Service in a Code Division Multiple Access (CDMA) 2000 system. To this end, the present invention calculates the difference in the transmission power value of each channel and adjusts the transmission power value of the channel so as to reduce the magnitude of the difference value.

More specifically, the apparatus of the present invention is a power control apparatus for forward power control of a mobile communication system, the first digital signal processor for performing signal processing for transmission of the first channel, which is one of the forward channels (DSP) And a signal processing for transmitting a second channel among forward channels, and adjusting a transmit power value of the second channel according to a difference between the transmit power value of the first channel and the transmit power value of the second channel. The difference between the two transmission power values is calculated by receiving a transmission power value of the first channel and a transmission power value of the second channel from a second DSP, the first DSP and the second DSP, and calculating the difference between the two transmission power values. And a transmission power determination unit for outputting a difference value of power to the second DSP.

In addition, the method of the present invention using such a device includes a first process of receiving a transmission power value of each of a first channel and a second channel of a forward channel in a power control method for forward power control of a mobile communication system; And a second step of calculating a difference value between the received transmission powers of the two channels, and a third step of adjusting the transmission power value of the second channel according to the difference value of the transmission power. Control method.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. An embodiment to be described below relates to a case of controlling a transmit power value of a DCCH with respect to a transmit power value of an FCH. That is, in the present embodiment, the FCH may be the first channel and the DCCH may be the second channel.

On the other hand, in the operation of the current FCH, commercial DSPs apply power control to the transmit channel gain value received from an upper block (e.g., the transmit power determiner of the present invention), thereby applying each channel (CE). The transmission power for each star will be determined. The tx channel gain determined in this process is reported to the upper level through the host port interface (HPI) in units of power control groups (PCGs). The upper block reads the transmission channel gain value on the HPI at a specific PCG time (the first PCG time based on the frame offset). Where PCG is the smallest unit in which power control occurs, typically 1.25ms.

In the present invention, the power control for synchronizing the transmission power of the DCCH in the Concurrent Service is performed by using the reporting process of the transmission channel gain value.

5 is a diagram illustrating a power control device according to the present invention.

As shown in FIG. 5, the present invention may be implemented using a device including a channel card 500 and a transmission power determiner 510. The power control apparatus according to the present invention, including the channel card 500 and the transmission power determination unit 510 of FIG. 5, may be included in a base station (BS). Meanwhile, in a system in which the BS is divided into a base station controller (BSC) 110 and a base transceiver system (BTS) 120, the channel card 500 determines the transmission power of the BTS 120. The unit 510 is generally included in the BSC 110.

The channel card 500 includes a DSP and uses this to perform signal processing for each channel. In the present invention, the channel card 500 includes at least DSP A which performs signal processing on the FCH and DSP B which performs signal processing on the DCCH. The channel card 500 loads the transmission power values of the FCH and the DCCH in a reverse traffic frame and outputs them to the transmission power determination unit 510 which is an upper block. In addition, the channel card 500 may receive a difference value between the transmit powers of the FCH and the DCCH from the transmit power determiner 510 and determine the transmit power of the FCH and the DCCH accordingly.

The transmit power determiner 510 receives the transmit power values of the channels from the DSP included in the channel card 500, calculates a difference value of the transmit powers, and outputs the difference values to the DSP.

6a to c are diagrams illustrating an embodiment of power control using the power control device proposed by the present invention.

As shown in FIG. 6A, the channel card 500 includes a DSP A which performs signal processing on an FCH and a DSP B which performs signal processing on a DCCH. DSP A and DSP B load transmission power values of FCH and DCCH in reverse traffic frames for each frame and output the same to the transmission power determining unit 510. Here, since the CDMA 2000 system generally uses a frame having a size of 20 ms, the output process of the transmission power value is also generally made 20 ms in consideration of the size of the frame. On the other hand, although the control of the transmission power value is generally made in one frame period, depending on the characteristics of the system may be made of several frames or more than two times in one frame. In addition, DSP A and DSP B generally output the transmission power values of the FCH and DCCH to the transmission power determination unit 510 in the first PCG of each power control cycle.

The transmit power determiner 510 calculates a difference between the transmit power of the FCH received from DSP A and DSP B and the transmit power of the DCCH, and again calculates the difference between the calculated transmit powers of the two channels. Output to The calculated difference between the two transmit powers may also be referred to as a delta value.

As illustrated in FIG. 6B, the transmit power determiner 510 outputs a delta value, which is a difference between two transmit powers, to DSP A and DSP B, respectively. Of course, if the transmission power values of the FCH and the DCCH are synchronized by adjusting only the transmission power values of the DCCH, the delta value may be output only to the DSP B.

As shown in FIG. 6C, the DSP B of the channel card 500 updates the transmit power value of the DCCH according to the delta value received from the transmit power determiner 510, and sets the transmit power value of the DCCH to the transmit power value of the FCH. Synchronize to. That is, the DSP B decreases the transmission power value of the DCCH when the delta value received from the transmission power determining unit 510 indicates that the transmission power value of the DCCH is greater than the transmission power value of the FCH, and the delta value is the transmission power value of the DCCH. If it is smaller than the transmit power value of the FCH, the difference between the transmit power value of the FCH and the transmit power value of the DCCH is decreased by increasing the transmit power value of the DCCH. These processes are described again with reference to the flowchart.

7 is a flowchart illustrating a power control process according to an embodiment of the present invention.

In step 700 of FIG. 7, the transmit power determiner 510 receives transmit power values of two channels, FCH and DCCH, from DSP A and DSP B of the channel card 500. In general, the transmit power values of FCH and DCCH are output by DSP A and DSP B included in the reverse traffic frame at the beginning of each frame. Meanwhile, the transmission power determiner 510 generally receives the transmission power values of the FCH and the DCCH at the first PCG of each frame, that is, the frame boundary. In this case, the transmission power determiner 510 preferably receives a transmission power value based on a full rate of FCH and DCCH from DSP A and DSP B.

In step 702, the transmission power determiner 510 calculates a delta value that is a difference between the transmission power of the FCH and the transmission power of the DCCH. The delta value can be both negative and positive, and in the case of a negative delta value, it is preferable to perform a complement operation.

In step 704, the transmission power determiner 510 outputs a delta value to DSP B of the channel card 500 at the time point of outputting the forward DCCH traffic frame to DSP B every frame, that is, 20 ms. The delta value at this time is a difference value between the transmission powers of the FCH and the DCCH every 20ms.

In operation 706, the DSP B adjusts a transmission power value of the DCCH such that a difference between the transmission power value of the FCH and the transmission power value of the DCCH is reduced with reference to the delta value received from the transmission power determination unit 510.

The processes of steps 700 to 706 will be described with reference to the drawings.

8 is a diagram illustrating a process of performing power control on each frame according to an embodiment of the present invention.

8A-8D are power control procedures for one frame, and FIG. 8E shows the start of the power control procedure in the next frame. That is, FIGS. 8A and 8E are the same process except that the performed frame is different.

FIG. 8A corresponds to step 700 of FIG. 7. In FIG. 8A, the transmit power determiner 510 receives the transmit power value of the FCH and the transmit power value of the DCCH from DSP A and DSP B, respectively, in the first PCG of every frame.

8B corresponds to step 702 of FIG. 7, and the transmission power determiner 510 calculates a delta value that is a difference between two transmission powers from the transmission power value of the FCH and the DCCH transmission power value input in FIG. 8A. .

8C corresponds to step 704 of FIG. 7. In FIG. 8C, the transmission power determiner 510 outputs the delta value calculated in FIG. 8B to the DSP B. Of course, the transmission power determiner 510 may output a delta value to DSP A to adjust the transmission power value of the FCH, or output a delta value to both DSP A and DSP B to adjust the transmission output value of both the FCH and DCCH. . However, in the present embodiment in which the transmit power value of the FCH is synchronized with the transmit power value of the DCCH, the delta value is output to the DSP B to adjust the transmit power value of the DCCH.

Meanwhile, in FIG. 8C, the time point when the DSP B receives the forward DCCH traffic frame from the transmission power determiner 510 becomes the 14th PCG based on the frame offset. The DSP B adjusts the transmit power value of the DCCH according to the delta value received from the transmit power determiner 510 together with the forward DCCH traffic frame, and then transmits the packet according to the adjusted transmit power value from the frame boundary. At the frame boundary where the forward DCCH traffic frame is transmitted, the DCCH transmit power value adjusted using the delta value received from the upper layer at the time of receiving the packet is synchronized with the FCH. That is, after receiving the delta value, which is a difference between the FCH and DCCH transmission powers for the previous 20ms forward frame, from the transmission power determining unit 510, the DCCH transmission power value for the next 20ms forward frame is determined using the delta value. It is similar to.

FIG. 9 is a diagram according to the present invention and illustrates transmission power values of FCH and DCCH in which power control is performed according to the present embodiment.

In FIG. 9, since the transmit power value of the FCH and the transmit power value of the DCCH are almost the same, it is as if the transmit power value of the FCH is not displayed. 9, it can be seen that transmission power values of the FCH and the DCCH are synchronized.

Meanwhile, the present invention has been described with reference to an embodiment of controlling transmission power of FCH and DCCH, but this is to help understanding of the present invention, and the present invention is equally applicable to channels other than FCH and DCCH. Can be. In addition, the present invention can be extended to not only two channels but also more channels. For example, if the present invention is applied to three channels, the difference value between two channels is calculated based on the transmission power value of one channel, and then the difference value can be reduced. It is to adjust the transmit power value of two channels. In the same way, the present invention can be applied to four or more channels.

By applying the present invention as described above, the system can operate more stably by synchronizing the transmission power values of a plurality of channels used in the concurrent service.

The present invention implements efficient forward power control for the DCCH through synchronizing the transmission power values for the FCH and DCCH having different channel characteristics to ensure stable operation and performance in the radio section for the DCCH channel. This can increase stability and efficiency for concurrent services that use FCH and DCCH simultaneously.

1 is a configuration diagram of a mobile communication system.

2 illustrates a forward channel structure of a code division multiple access (CDMA) 2000 system.

FIG. 3 is a diagram according to the related art, and illustrates transmission power values of a fundamental channel (FCH) and a dedicated control channel (DCCH) in which power control on a channel is not performed. A diagram showing the case where the transmit power value of is lower than the transmit power value of the FCH.

4 is a diagram according to the prior art, in which the transmission power value of the DCCH is higher than the transmission power value of the FCH.

5 illustrates a power control device according to the present invention.

6 is a diagram illustrating power control using a power control device proposed by the present invention.

7 is a flow chart of a power control process according to an embodiment of the present invention.

8 illustrates a process of performing power control on each frame, according to an embodiment of the present invention.

FIG. 9 is a diagram according to the present invention, showing transmission power values of FCH and DCCH in which power control is performed;

Claims (10)

In the power control device for the forward power control of the mobile communication system, A first digital signaling processor (DSP) for performing signal processing for transmission of a first channel, which is one of the forward channels; A second DSP for performing signal processing for transmission of a second channel among the forward channels, and adjusting a transmission power value of the second channel according to a difference between the transmission power value of the first channel and the transmission power value of the second channel; , The difference between the two transmit power values is calculated by receiving the transmit power value of the first channel and the transmit power value of the second channel from the first DSP and the second DSP, and calculate the difference between the calculated transmit powers of the two channels. And a transmission power determination unit for outputting the second power to the second DSP. The method of claim 1, The first DSP receives a difference value between the transmit powers of the two channels from the transmit power determiner and adjusts a transmit power value of the first channel according to the difference value. The method of claim 1, The transmission power determiner receives the transmission power values of the first channel and the second channel from the first DSP and the second DSP every frame, calculates a difference between the two transmission powers, and outputs the calculated values to the second DSP. Power control device of a mobile communication system. The method of claim 1, The transmission power determining unit receives a transmission power value of each channel from the first power control group (PCG) of each frame of the first channel and the second channel. The method of claim 1, The first channel is a basic channel (Fundamental Channel, FCH), the second channel is a dedicated control channel (Power Control Device) of the mobile communication system. The method of claim 1, And the second DSP adjusts a transmission power value of the second channel so as to reduce a difference value between the transmission powers of the two channels. In the power control method for the forward power control of the mobile communication system, A first process of receiving a transmission power value of each of a first channel and a second channel of the forward channels; A second process of calculating a difference between transmission powers of the received two channels; And a third process of adjusting a transmission power value of the second channel according to the difference value of the transmission power. The method of claim 7, wherein The power control method of the mobile communication system is to input the transmission power value of the first step every frame. The method of claim 7, wherein Wherein the first channel is a basic channel and the second channel is a designated control channel. The method of claim 7, wherein Adjusting the transmission power value of the third process is to reduce the difference value of the transmission power of the two channels.