KR20030035605A - Method of Transmission Power Control for High Speed Downlink Packet Access Indicator in Asynchronous Mobile Communication System - Google Patents

Abstract

PURPOSE: A method for controlling transmission power to a high speed downlink packet access service indicator in an asynchronous mobile communication system is provided to control properly power of a transmission type indicator under any situation in a hand-off region. CONSTITUTION: The first node B(601) is a primary base station for transmitting a forward DCH(Dedicated Channel) and an HS_DSCH(High Speed Downlink Shared Channel) to a UE(User Element)(611). The second node B(603) is a secondary base station(node B) newly included as an active set and transmits only a forward DCH to the UE(611). The UE(611) receives the HS_DSCH and a forward DCH from the first node B(601) and a forward DCH from the second node B(603). The UE(611) also transmits a UL_DCH. The UL_DCH is a signal that the UE(611) transmits without distinction of nodes. The first node B(601) and the second node B(603) receive the UL_DCH transmitted from the UE(611) and analyze a channel state between the node B and the UE.

Description

Transmission power control scheme for high speed downlink packet access indicator in asynchronous mobile communication system {Method of Transmission Power Control for High Speed Downlink Packet Access Indicator in Asynchronous Mobile Communication System}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control apparatus and method in an asynchronous mobile communication system, and more particularly, to an apparatus for controlling transmission power of an indicator for a high speed downlink packet access (HSDPA) service. And to a method.

In general, a wideband code division multiple access (W-CDMA) scheme, which is an asynchronous scheme used in Europe, is a high-speed forward common channel (High) for HSDPA. Speed Downlink Shared Channel, hereinafter referred to as "HS_DSCH"). The HS_DSCH refers to a channel shared by various mobile terminals (hereinafter referred to as "UE") that support the HSDPA. In particular, the HS_DSCH is a channel allocated for transmission in a plurality of UEs by packet unit or other high-speed data according to the HSDPA service in a radio frame unit having a period of 10 ms. Thus, the HS_DSCH is time-divided and assigned to each of the several UEs.

Meanwhile, the W-CDMA scheme employing a two-stage approach uses a forward dedicated channel (hereinafter referred to as "DCH") together with the HS_DSCH. High-speed packet data for HSDPA is carried through the HS_DSCH, and an indicator thereof (hereinafter referred to as "HI") is included in the slot structure of the forward DCH and transmitted. The forward DCH has a structure in which power control can be performed in units of slots, and the actual transmit power control is referred to as a transmission power control coefficient (TPC) transmitted from UEs through respective slots of the reverse DCH. Through).

Through the HS_DSCH, several frames may be continuously transmitted or only one frame may be transmitted for one UE. When to send the HS_DSCH to each of the multiple UEs is determined by scheduling of a base station higher layer, which informs each of the multiple UEs through HI configured according to signaling of the higher layer or the forward DCH. .

The radio frame structure of the HS_DSCH for transmitting data according to the HSDPA service is shown in FIG. 1A. As shown in FIG. 1A, one radio frame has a period of 10 ms in the HS_DSCH 101, and one radio frame includes 15 slots (Slot # 1 to Slot # 14). Each of the 15 slots Slot # 1 to Slot # 14 consists of a data area of 2560 chips (20 × 2 ^k bits, where k = 0,1, ..., 6), and corresponds to each UE. One or a plurality of slots may be allocated.

Meanwhile, from the base station providing the HSDPA service, the forward DCH is transmitted together with the HS_DSCH through a forward physical channel (hereinafter, referred to as a "DPCH"). The structure of the forward DPCH for transmitting the forward DCH is shown in FIG. 1B.

Referring to FIG. 1B, in the forward DPCH 111, 15 slots Slot # 1 to Slot # 14 constitute one radio frame, and the radio frame has a period of 10ms. Each of the slots Slot # 1 to Slot # 14 has two data areas 112 and 116, a TPC area 113, and a transmission format combination indicator (hereinafter referred to as a “TFCI”) area ( 114), HI region 115 and pilot region (Pilot) 117. One slot of the forward DPCH may have various structures depending on the length of each of the regions.

The DATA1 region 112 and the DATA2 region 116 shown in FIG. 1B are referred to as a forward dedicated data physical channel (hereinafter, referred to as a "DPDCH"), and are used for transmitting user data or signaling information of an upper layer. Channel. The TPC region 113, the TFCI region 114, the HI region 115, and the pilot region 117 constitute a forward dedicated control physical channel (hereinafter referred to as “DPCCH”). The TPC area 113 is an area for transmitting a command for adjusting the transmission power of reverse channels transmitted from the UE, and the pilot area 117 transmits a pilot signal used by the UE to measure transmission power of a forward signal. It is an area to do. The transmit power measured by the pilot region 117 is used for power control of the forward signal received by the UE. In addition, the TFCI region 114 is a region for transmitting a codeword for informing the UEs when transport channels having different data rates are used as the forward DPCH. That is, the TFCI area 114 transmits TFCI corresponding to each of 1024 types of transport format combinations (hereinafter, referred to as "TFC"). Lastly, the HI area 115 is an area in which an indicator indicating whether to transmit the HS_DSCH according to the HSDPA service corresponding to the corresponding UE is transmitted. In case of transmitting the packet data to a specific UE through the HSDSCH, first, the HI filter of the DPCH channel indicates that there is data. Among the 15 slots, the slot may include a slot in which the HI field exists and a slot in which the HI field does not exist. The terminal and the base station promise in advance which time slot the HI bit will be transmitted, and transmit the field in which the HI bit is not transmitted in the form of a predetermined UMTS standard Release '99. Therefore, when the HSDPA service is not supported, the HI region 115 does not exist because the HS_DSCH is not transmitted.

However, when a predetermined UE that performs the HSDPA service moves to a soft handover area, a problem may occur in which the HSDPA service cannot be normally performed.

2 is a diagram illustrating a flow of forward and reverse signals when a predetermined UE receiving an HS_DSCH according to the HSDPA service is located in a soft handover area. In FIG. 2, only two Node Bs (base station transmitters) are considered for ease of explanation. In addition, it is assumed that each of the Node Bs belongs to different radio network controllers (hereinafter referred to as RNCs). The Node B and the RNC are terms used in an asynchronous mobile communication standard and are part of components of a UTRAN (hereinafter referred to as a "UTRAN"). The UTRAN collectively refers to other components in the asynchronous mobile communication standard except for the UE. The Node B is typically a term representing a base station, and the RNC is an element of the UTRAN controlling the Node Bs. There are a plurality of Node Bs controlled by the RNC.

The soft handover (hereinafter referred to as "SHO") refers to a procedure in which a UE moves from a current Node B to another Node B without interrupting a service currently being performed. To this end, when the UE moves to the soft handover area, the UE establishes a communication channel with the current Node B and the neighboring Node B to simultaneously communicate with the two Node Bs. On the other hand, if the received signal quality from any one Node B while performing communication with the two Node Bs does not reach an appropriate level, the channel with the corresponding Node B is released, and with the remaining one Node B with good received signal quality Maintain existing communication by keeping only the channel. Thus, the UE can continue to perform communication without interruption of communication.

More specifically, the soft handover, when the UE reaches a soft handover area, the UE adjusts the transmit power of Node Bs receiving signals from multiple base stations and transmitting to the UE. That is, the power strength received from the source Node B, which previously received the signal, and the power strength of the signal received from the target base station newly transmitting the signal to the UE are compared with the reference power by a simple or weighted sum. By determining whether the received signal strength is sufficient or not, a signal for adjusting the transmission power of the two Node Bs is transmitted to the Node Bs to adjust the transmission power of the Node Bs.

Referring to FIG. 2, the soft handover considering the performance of the HSDPA service, the first node B 201 transmits the HS_DSCH and the corresponding forward DPCH to the UE 211 according to the performance of the HSDPA service. In this case, the first node B 201 becomes a primary node B with respect to the UE 211. The second node B 203 transmits only a forward signal (forward DPCH) to the UE 211 when the UE 211 moves to the soft handover target region. In this case, the second node B 203 becomes a secondary node B with respect to the UE 211. As such, when the UE 211 is located in the soft handover area, a set of Node Bs capable of transmitting a signal to the UE 211 is called an active set.

However, as illustrated in FIG. 2, a series of problems may occur when the UE 211 receiving the HS_DSCH from the predetermined Node B 201 is located in the soft handover area.

This is because the HS_DSCH does not support soft handover as the first cause of the series of problems. This is because the HS_DSCH does not support soft handover because the HS_DSCH uses a lot of channel resources of the Node B as the HS_DSCH transmits relatively high speed data compared to the forward DCH. That is, in order for the HS_DSCH to support soft handover, channel resources are inefficiently operated because the source node B and the target node B must use the same channel resources for the high-speed data transmission during the soft handover. . In addition, in order to support soft handover of the HS_DSCH because the HS_DSCH does not support soft handover, all Node Bs in an active set must have an algorithm for supporting the HS_DSCH. However, this is because all Node Bs have to synchronize to implement the algorithm. That is, since the HS_DSCH is a channel shared by a plurality of UEs, precise scheduling of time points used by each UE is performed. In order to transmit the HS_DSCH to the UE from other Node Bs in consideration of the scheduling, accurate synchronization must be performed. . However, in the asynchronous mobile communication system, since the synchronization between the respective Node Bs is not matched, a timing problem may occur during soft handover. To solve this problem, implementation difficulties occur.

The second cause of the above-mentioned problems is the soft combining performed by the UE located in the soft handover area.

In FIG. 2, forward DPCHs transmitted from the first node B 201 and the second node B 203 and received by the UE 211 are concatenated and interpreted. The connection sum means that different Node Bs 201 and 203 transmit the same DPCH signal to the UE 211 and the UE combines respective signals received from the respective Node Bs. The purpose of the concatenation sum is to reduce the effects of noise by summing up the same information received through different paths and then interpreting them. That is, the connection sum is possible only when the same information is received from different Node Bs, and when different information is received, only the noise component is increased by the connection sum. Therefore, in the interpretation of the forward DCH, the downlink signals transmitted from the respective Node Bs 201 and 203 are interpreted in conjunction with each other except for the TPC 112 having different information from each other.

As described above, the HI bit 115 will also be concatenated and interpreted. In this case, when the UE 211 located in the soft handover area receives both the HS_DSCH and the forward DPCH from one Node B 201 and receives only the forward DCH from the other Node B 203, the UE 211. Will receive the HI from only one Node B. In this case, soft coupling cannot be performed. However, since the UE receives the Node B signals from the plurality of active base stations in the soft handover area and controls the transmission power of the Node Bs using the soft combined power, the signal power of the Node B transmitting the HSDSCH among the Node B signals. In spite of the shortage, if the signal power of the other Node B is sufficient, the UE sends a command to the Node Bs to lower the transmission power. In this case, since the node B transmitting the HSDSCH also lowers the transmission power, the probability that an error occurs due to insufficient transmission power of the HI bit is high. Therefore, it is necessary to appropriately control the transmit power of the HI bit. In order to control the transmission power of the HI bit, message transmission processes between a SRNC (Serving RNC), a Node B, and a UE should be defined.

Accordingly, an object of the present invention for solving the above problems is to provide an apparatus and method for performing reliable power control of an indicator for a high speed forward packet access (HSDPA) service in an asynchronous mobile communication system.

Another object of the present invention is to provide an apparatus and a method for accurately receiving a fast forward packet access indicator (HI) transmitted from a base station (UE) in a soft handover area.

It is still another object of the present invention to provide an apparatus and method for reliably transmitting a fast forward packet access indicator (HI) to a mobile station (UE) located in a soft handover area by a base station transmitting a fast forward common channel (HS_DSCH). Is in.

It is still another object of the present invention to provide an apparatus and method for granting a separate power offset to an indicator for reliable power control of an indicator for a high speed forward packet access (HSDPA) service in an asynchronous mobile communication system. .

Another object of the present invention is to determine the relative power offset of the HI in consideration of the number of Node B other than the primary base station to which the RNC transmits HS_DSCH when the RNC transmitting the HS_DSCH transmits HI. An apparatus and method for controlling the transmit power of HI for HS_DSCH are provided.

It is still another object of the present invention to measure the size of a common pilot signal and a pilot signal of each Node B in an active set by a UE receiving an HS_DSCH, and then transmit the result to the RNC transmitting the HS_DSCH so that the RNC receives the RNC. The present invention provides a method for controlling the transmission power of the HS_DSCH transmitted from the base station based on the data received from the UE.

It is still another object of the present invention to provide an apparatus and method for transmitting information so that a UE receiving an HS_DSCH can control a magnitude of a transmission power of HI transmitted from the primary base station using a feedback information field of UL_DCH. .

It is still another object of the present invention to determine the data to be transmitted in the feedback information field of UL_DCH to control the transmit power of HI by the UE receiving the HS_DSCH, the magnitude of the common pilot signal and the pilot signal of the individual Node Bs in the active set. The present invention provides an apparatus and method for measuring and determining the size of.

The present invention according to the first aspect for achieving the above object is the first base station of the plurality of mobile terminals in the first base station of the mobile communication system for providing a high speed forward packet access service to a plurality of mobile terminals In the method for performing power control for an indicator indicating the presence of packet data according to the fast forward packet access service transmitted to a predetermined mobile terminal located in a soft handover area with another second base station adjacent to the predetermined movement. Transmitting, by the terminal, channel environment information with the first base station and channel environment information with the second base station to the first base station, and wherein the first base station is determined by the channel environment information from the predetermined mobile terminal. Determine the power offset of the indicator to send to the mobile terminal, and to the power strength to transmit the packet data It characterized in that it comprises the step of transmitting the indicator by adding the power offset group.

The present invention according to the second aspect for achieving the above object is a first base station of the plurality of mobile terminals in a first base station of a mobile communication system providing a high speed forward packet access service to a plurality of mobile terminals In the method for performing a power control for the indicator indicating the presence of the packet data according to the fast forward packet access service transmitted to a predetermined mobile terminal located in a soft handover area with another second base station adjacent to the predetermined movement The terminal measures channel environment information with the first base station and channel environment information with the second base station, and determines the power offset of the indicator transmitted from the first base station based on the channel environment information. Transmitting to a base station; and powering the indicator of the indicator from the mobile station by the first base station. Receiving a set, and the power intensity for transmitting the packet data, it characterized in that it comprises the step of transmitting the indicator by adding the power offset.

Figure 1a is a view showing the structure of a conventional downlink channel.

Figure 1b is a view showing the structure of a conventional dedicated channel.

2 is a view for explaining dedicated power control in a conventional soft handover area (SHO).

3 is a diagram for explaining fast forward packet access indicator transmit power control in a conventional soft handover area (SHO);

4 is a diagram illustrating a power offset of a dedicated channel in a soft handover area (SHO) according to an embodiment of the present invention.

5A is a diagram showing a transmission power relationship between a conventional fast forward packet access indicator region and a data region.

5B and 5C illustrate a transmission power relationship between a fast forward packet access indicator region and a data region according to embodiments of the present invention.

6 is a diagram illustrating a process of determining a transmit power offset of a fast forward packet access indicator according to an embodiment of the present invention.

7A illustrates the structure of a feedback information field (FBI) of a reverse dedicated control physical channel according to an embodiment of the present invention.

FIG. 7B illustrates a structure of an uplink-oriented channel transmitted to the feedback information field of FIG. 7A. FIG.

8 is a graph illustrating a change in transmit power of a base station transmitting a fast forward packet access indicator according to an embodiment of the present invention.

9 illustrates a receiver structure of a mobile terminal according to an embodiment of the present invention.

10 is a view showing the structure of a transmitter of a mobile terminal according to an embodiment of the present invention.

11 is a diagram illustrating a base station receiver structure according to an embodiment of the present invention.

12 illustrates a base station transmitter structure according to an embodiment of the present invention.

13 is a diagram illustrating a procedure for power control of a fast forward packet access indicator according to an embodiment of the present invention.

14 is a diagram illustrating a power offset transmission path from a data frame transmission and a radio network controller (RNC) to a base station according to an embodiment of the present invention.

15 illustrates a frame protocol structure from an SRNC to a base station according to an embodiment of the present invention.

16 is a diagram illustrating a message structure in which a wireless network controller transmits a power offset of a fast forward packet access indicator according to an embodiment of the present invention to a base station.

17 is a view showing the structure of a data frame transmitted to a base station according to an embodiment of the present invention.

18 is a diagram illustrating a control flow of a process in which an SRNC transmits a power offset to a base station supporting fast forward packet access according to an embodiment of the present invention.

19 is a diagram illustrating a control flow of a process in which an SRNC transmits a control and a data frame to a base station through a DRNC according to an embodiment of the present invention.

20 is a diagram illustrating a structure of a control frame to which a power offset is added according to an embodiment of the present invention.

21 is a diagram showing the structure of a data frame to which a power offset is added according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the following description of the present invention, various embodiments of performing power control on the indicator so that an indicator (HI) indicating the presence of packet data according to the HSDPA service can be correctly delivered to a UE located in a soft handover area will be proposed. will be.

3 is a diagram illustrating the concept of the present invention for accurately delivering HI to a UE located in a soft handover area. In FIG. 3, for the purpose of understanding the present invention, it is assumed that there are two Node Bs in the active set of the UE, and each of the Node Bs in the active set belongs to a different RNC.

Referring to FIG. 3, the UE 311 has a first node B 305 and a second node B 335 in an active set. The UE 311 receives the forward DPCH and the HS_DSCH 321 from the first node B 305, but receives only the forward DPCH 323 from the second node B 335. Therefore, in the prior art, since the HI is transmitted with the same transmission power as pilot, TFCI, or DPDCH, which is another signal carried on the forward DCH, the UE 311 that receives the forward DCH cannot correctly interpret the HI. Could occur. In this case, a predetermined transmission power offset is applied to the HI transmitted by the forward DCH from the first node B 305. The transmission power offset applied to the HI may be determined by the RNC A 303 or by information 325 transmitted by the UE 311 having received the HS_DSCH of FIG. 3. The information 325 is data for the transmission power offset of the HI.

The concept of the present invention described above with reference to FIGS. 4 and 5A to 5C will be described in more detail as follows.

4 is a diagram illustrating setting of transmission power of a forward DCH transmitted in downlink transmission from a Node B to a UE in a third generation asynchronous mobile communication standard. In FIG. 4, Data 1 401 and Data 2 405 are transmitted to the transmission power P 411. The transmission power P 411 is determined by the TPC 402 transmitted from the UE and the quality of service (hereinafter referred to as "QoS") of data transmitted to the data 1 401 and the data 2 405. Is determined. The TPC 402, the TFCI 403, and the Pilot 406 are configured to provide the P _offset1 412, the P _offset2 413, the power P 411 to which the Data 1 401 and the Data 2 405 are transmitted. P _offset3 (414) is applied and transmitted. The value of the _{P offset1 (412), P offset2} (413), P offset3 (414) is determined by a higher layer. The HI 404 may be disposed in any of the TFCI 403, the data 401, 405, or the pilot 406. For example, when the HI 404 is replaced by a part of the Data 2 405 region of FIG. 4, the conventional transmission power control technique is illustrated in FIG. 5A. As the HI 501 and Data 2 502 of FIG. 5A are transmitted by the power offset P 411 of the data portion, there is no difference in the transmission power of the HI 501 and the Data 2 502. As described above, when there is no difference in the transmission power between the HI 501 and the data 2 502, a case where the reception power of the HI received by the UE is insufficient may occur.

6B and 6C are techniques proposed in the present invention to overcome the problems of the prior art as described above.

First, FIG. 6B illustrates a method of transmitting the transmission power of HI 511 and Data 2 512 differently. The Data 2 512 is transmitted to the transmit power P 411 of the data portion as in the prior art, and the HI 511 is transmitted by applying a power offset P offset ₄ 415 only for the HI. The power offset P _offset4 415 for HI may be determined by the RNC transmitting the HS_DSCH or by the information transmitted by the UE receiving the HS_DSCH.

FIG. 6C illustrates a method of transmitting the same transmission power of HI 521 and Data 2 522. That is, the transmission power of the Data 2 522 and the HI 521 is determined by adding the HI transmission power offset P _offset4 415 to the transmission power P 411 of the data portion. In the method of FIG. 5C, the UE reception power of the data 2 522 may be slightly excessive, but the interference due to the reception power of the HI 521 region is small because the portion occupied by the HI 521 in one slot of the forward DPCH is small. Noise generation will be minimal. In addition, since the received power of the HI 521 is the power of the transmission that the HI 521 can be correctly interpreted, there is an advantage of preventing error interpretation of the HI.

3, 4, 5b and 5c, the present invention described with reference to FIG. 5c again, the UE receiving the HS_DSCH is in the soft handover area, the Node Bs in the active set of the UE are each different RNC When the HI for the HS_DSCH is transmitted by being replaced by a part of the Data2 region, a separate transmission power offset is used to set the transmission power of the HI. The use of a separate transmit power offset for the HI is because the UE received power of the HI received from the primary base station does not have enough power to correctly interpret the HI.

Meanwhile, the above-described bar defines that a separate transmission power offset should be used for HI, and in an embodiment of the present invention to be described later, three methods of determining a separate transmission power offset for the HI are largely defined. I suggest it.

The first method is a method in which the UE reports channel environment information between each Node Bs in the current active set and the UE to the UTRAN so that the UTRAN determines the transmit power offset of the HI. The second method is a method in which the UE measures channel environment information between each Node Bs in the current active set and the UE to determine the transmit power offset of the HI and report it to the UTRAN. The third method is a method in which the UTRAN determines a transmission power offset to apply to HI according to the type of Node Bs in the active set of the current UE.

The first method may be performed by using a HI transmission power offset determined by using a site selection signal ("SSDT") used in a conventional asynchronous mobile communication standard. It is also possible to use several variable HI transmit power offsets. That is, in addition to the measurement reported by the UE, the UTRAN determines the transmission power offset of the HI according to the number and type of Node Bs in the active set of the UE. In this case, the number of the Node Bs is the number of Node Bs in the active set, and the type of the Node Bs is whether or not the Node Bs in the active set belong to the same RNC as the Node B transmitting the HS_DSCH.

In the method of determining the transmit power of HI using the SSDT, an RNC or a node B determines a transmit power offset to be applied to HI depending on whether Node B indicated by the temporary identifier transmitted by the UE indicates Node B transmitting HS_DSCH. Is to decide. That is, when the Node B indicated by the temporary identifier transmitted by the UE indicates the Node B transmitting the HS_DSCH, the RNC or the Node B applies the power offset P _offset4 fixed to the forward DPCH transmission power P with the transmission power of the HI for _{HS_DSCH} . To transmit.

In the method using the SSDT, if the Node B transmitting the HS_DSCH is the primary base station, the channel environment between the Node B and the UE is the best. Therefore, the HI transmission power offset is not required or a slightly larger value is applied. However, if the Node B is not the primary base station, it means that the channel environment with the UE receiving the HS_DSCH is not good. Therefore, a large HI power offset is required.

In addition, when using the SSDT, the UTRAN uses a fixed value for the transmit power offset of HI. That is, a fixed power offset is used for HI depending on whether the Node B transmitting the HS_DSCH is the primary base station. In addition to the fixed power offset, the channel environment of the Node Bs in the active set of the UE and the UE is changed. A variable power offset determined according to may be used for HI. An example in which the variable power offset can be used for HI is as described below.

The UE receiving the HS_DSCH reports to the UTRAN information about the channel environment between the current UE and the Node Bs in the active set. The UTRAN receives information about the channel environment between the UE transmitted from the UE and the Node Bs in the active set and the channel environment between the UE and the Node Bs transmitting the HI for HS_DSCH. The UTRAN uses the received information to determine a proper transmit power offset to be used by the Node B to transmit HI to the UE, and then transmits the transmit power offset information to the Node B.

A method for determining information on a transmission power offset to be used for transmission of HI by a UTRAN using information transmitted by the UE, wherein the UE receives pilot fields of a common pilot channel and a downlink dedicated channel received from respective Node Bs in an active set. The information to be transmitted is determined by using a measurement value such as a signal magnitude of. The measurement of the common pilot channel and the measurement of the pilot field of the downlink dedicated channel are examples of information used when the UE determines information to transmit to the UTRAN.

As an example of a process for determining information to be transmitted to the UTRAN by the UE, the UE has a larger signal size of a common pilot channel currently being received than a signal size of a previous common pilot channel of the Node B transmitting the HS_DSCH to the UE. If it is determined that the channel condition is good, information corresponding to the current channel condition is transmitted to the UTRAN. See Table 1 below to help understand the examples. In Table 1 below, it is assumed that the number of information transmitted by the UE to the UTRAN is 6 and the number of Node Bs in the active set of the UE is 2, so that each Node B is a Node B belonging to a different RNC.

In addition, it is assumed that the information indicating the current channel state uses a code for SSDT used in the 3G asynchronous mobile communication standard. In addition to the code for the SSDT may be transmitted using a separate encoding method. The UE to transmit the information about the channel status to the UTRAN as the basis of the determination of the channel status is the signal size of the common pilot channel at the time of the first entry into the soft handover region, and since then the UE is informed about the channel status. It is assumed that the size of the common pilot channel at the time of transmission.

Difference between reference and measured values (common pilot signal magnitude) Channel Status (UE Judgment) Transmission code UTRAN applied power offset 6 dB or more Very bad 00000 4 dB 4 dB or more Fairly bad 01001 3 dB 2 dB or more Bad 11011 2 dB 0 dB or more usually 10010 1 dB -2 dB or more good 00111 0 dB -4 dB or more Very good 01110 -2 dB

In Table 1, the UTRAN may determine a transmission power offset to be used for the transmission of HI by judging a signal for a current channel state received from the UE at a predetermined interval, and determine a change in the received information during several receptions. To determine the transmit power offset to use for the transmission of HI. In Table 1, the size of the transmit power offset applied to the HI in the UTRAN is smaller than the difference in the signal size of the CPICH measured by the UE in order not to cause a sudden change in the transmit power of the HI transmitted to the UE. In addition, if necessary, the size of the transmission power offset may be equal to or different from the signal strength of the CPICH measured by the UE.

Among the methods of determining the size of the transmission power offset to be applied to the transmission power of HI, making the size of the transmission power offset smaller than the difference of the CPICH signal size can reduce the size of the interference signal to the adjacent base station. There is an advantage, but there is a disadvantage that the transmission power of HI is less than the proper transmission power.

Among the methods of determining the size of the transmission power offset to be applied to the transmission power of the HI, a method in which the size of the transmission power offset becomes equal to the difference of the CPICH signal size is applied to change the received signal of the UE as it is. There may be advantages. However, there may be a drawback of using a transmission power offset to be applied to HI without considering a difference in data rates of DPCH and CPICH.

The third method, the method of which the size of the transmit power offset is larger than the size difference of the CPICH signal has an advantage of allowing the UE to receive an appropriate signal quickly by increasing the transmit power of HI to be transmitted to the UE.

In addition to the signal size of the common pilot channel of the Node B transmitting the HS_DSCH used in Table 1, the UE measures the current channel state of the Node B, and the size and activity of the common pilot signal of all the Node Bs in the active set. The difference between the magnitude of the common pilot signal of the Node B transmitting the HS_DSCH in the set and the magnitude of the common pilot signal having the largest signal strength among the other Node Bs except the Node B, and the forward DPCCH of the Node B transmitting the HS_DSCH. The size of the pilot field, the size of the pilot field of the forward DPCCH transmitted from all Node Bs in the active set, the size of the pilot signal of the forward DPCCH of the node B transmitting HS_DSCH in the active set, and other nodes except the node B The difference in magnitude of the common pilot signal having the largest signal strength among the Bs may be used.

The second method of determining the transmit power offset of the HI is that the UE measures the channel environment with the Node Bs in the active set, and uses the result to determine the transmit power offset of the HI and transmit it to the UTRAN.

In the second method, the UE estimates a channel environment with each Node B by measuring CPICH received power received from each Node B in the active set of the UE, received power of a pilot field of a forward DPCCH, and the like. It is determined whether the Bs belong to the same RNC as the Node B transmitting the HS_DSCH to determine the transmit power offset of the HI to receive.

In determining the transmit power offset of the HI, the UE may transmit the offset of the transmit power of the HI to the UTRAN using the SSDT used in the first method. In addition, the eight codewords used in the SSDT may correspond to offsets of transmit powers of different HIs to be transmitted to the UTRAN. Finally, the power offset of HI may be transmitted to the UTRAN using another codeword in a feedback information field (hereinafter referred to as "FBI") of the UL_DPCCH in which the SSDT code is transmitted.

Among the methods of transmitting the offset of the transmit power of HI, a description of a method of using SSDT is as follows.

FIG. 6 is an example for explaining a method of determining a transmit power offset of a HI. In order to help the understanding of the present invention, the number of Node Bs in the active set of the UE is two, and each Node B is a different RNC. Assume that it belongs to.

Referring to FIG. 6, the first node B 601 is a primary base station transmitting a forward DCH and HS_DSCH to the UE 611, and the second node B 603 is a secondary base station newly included as an active set. B) transmits only forward DCH to the UE 611. The UE 611 receives the HS_DSCH and the forward DCH from the first node B 601, and receives the forward DCH from the second node B 603. In addition, UL_DCH is transmitted to the first node B 601 and the second node B 603. The UL_DCH is a signal transmitted by the UE 611 without discriminating the Node B, and the first Node B 601 and the second Node B 603 receive the UL_DCH transmitted from the UE 611 to receive the Node B. Analyze channel state between UE and UE, respectively.

In the method of transmitting the HI transmit power offset to the UTRAN using the SSDT, when the UE 611 enters a soft handover area, the UE 611 establishes a common pilot channel of the first node B 601 and the second. After receiving the common pilot channel of the Node B 603 together, the magnitude of the signal of each common pilot channel is measured to establish a primary base station among the first Node B 601 and the second Node B 603. Select. The temporary identifier of the Node B selected as the primary base station is transmitted by the UE 611 to a Feedback Information field of UL_DCH, hereinafter referred to as "FBI" field, and is a temporary identifier for the transmitted primary base station. The identifier is received by each Node B in the active set of the UE 611. The Node B transmitting the HS_DSCH among the Node Bs in the active set determines whether it is a primary base station or not, and determines a transmission power offset of HI to be transmitted to the UE 611.

The structure of the FBI is shown in Fig. 7A, and the total length is 2 bits. Reference numeral 701 of FIG. 7A denotes a field of feedback information transmitted from the UE 611 to the base station when the transmission antenna diversity is used in W-CDMA as the S-field among the FBI fields. Reference numeral 703 denotes a feedback information field transmitted by the UE 611 to the base station when SSDT is used in W-CDMA as a D-field. The S-field 701 has a length of 0 bits or 1 bit. When the S-field 701 is 0 bits, it is a case where transmission antenna diversity is not used. The D-field 703 has a length of 0, 1, 2 bits. If the D-field 703 is 0 bits, SSDT is not used. If 1 bit is used, the SSDT is used together with the transmission antenna diversity. If the D-field 703 is 2 bits, the SSDT is used alone. to be. When the SSDT is used, the information transmitted in the FBI field is a coded codeword of a temporary identifier indicating a primary base station.

Tables 2 and 3 below show SSDT codewords that change depending on the length of the FBI field and the channel environment between Node Bs in the active set of the UE 611. The values shown in Table 2 and Table 3 below are codewords currently used in the W-CDMA standard. Among the codewords of Tables 2 and 3, parenthesized code bits are not transmitted when they are not transmitted within one frame because the radio frame of HS_DSCH used in W-CDMA consists of 15 slots. Indicates a sign bit that does not.

ID Code ID label long code Medium code Short code a 000000000000000 (0) 0000000 00000 b 101010101010101 (0) 1010101 01001 c 011001100110011 (0) 0110011 11011 d 110011001100110 (0) 1100110 10010 e 000111100001111 (0) 0001111 00111 f 101101001011010 (0) 1011010 01110 g 011110000111100 (0) 0111100 11100 h 110100101101001 (0) 1101001 10101

Table 2 shows SSDT codewords when 1 bit FBI is used. That is, the case where SSDT is used together with transmission antenna diversity is shown.

ID Code ID label long code Medium code Short code a (0) 0000000 (0) 0000000 (0) 000 (0) 000 000000 b (0) 0000000 (1) 1111111 (0) 000 (1) 111 000111 c (0) 1010101 (0) 1010101 (0) 101 (0) 101 101101 d (0) 1010101 (1) 0101010 (0) 101 (1) 010 101010 e (0) 0110011 (0) 0110011 (0) 011 (0) 011 011011 f (0) 0110011 (1) 1001100 (0) 011 (1) 100 011100 g (0) 1100110 (0) 1100110 (0) 110 (0) 110 110110 h (0) 1100 110 (1) 0011001 (0) 110 (1) 001 110001

Table 3 shows SSDT codewords when 2 Bit FBI is used. That is, Table 3 shows a case where SSDT is used alone.

In the SSDT, <Table 2> and <Table 3> are selectively used according to the method used, and the node B in the active set uses the codewords shown in Table 2 or Table 3 according to the selected method. To be used as a temporary identifier. In addition, the primary base station is re-selected every predetermined period determined by the upper layer, and the UE 611 uses the temporary identifier of the primary base station to transmit to the Node Bs in the active set.

In the conventional method of transmitting the transmit power offset of the HI simply by using the SSDT, only two of the transmit power offsets of the HI may be determined regardless of whether the UE determines the transmit power offset of the HI or the UTRAN. Accordingly, in the present invention, in determining a value for the transmit power offset of HI, in the method determined by the UTRAN, the UE can transmit various information about the channel environment with each Node B in the active set. Meanwhile, in the method of determining by the UE, the SSDT ID code corresponds to the transmission power offset value of the HI or information that is a determination criterion of the HI transmission power offset so that the UE can transmit various transmission power offsets of HI to be transmitted to the UTRAN. It provides a method that can be transmitted by. The present invention also provides a method for using a code other than the SSDT code in transmitting information that is a determination criterion for the HI transmit power offset or the HI transmit power offset.

Therefore, in the present invention, the information on the transmission power offset of the HI, the information on the channel environment between the UE and the node B in the active set measured by the UE in the SSDT codes of Tables 2 and 3, and a separate encoding method The information about the power offset relative to the code generated by using is transmitted in correspondence.

Referring to FIG. 6 again, the UE 611 of FIG. 6 is dedicated to each common pilot channel and forward DCH transmitted from the first node B 601 and the second node B 603. Measure the pilot field. The type of Node B currently being measured, that is, whether the Node B currently being measured belongs to the same RNC as the primary base station transmitting the HS_DSCH, determines the power offset to be used for HI, or the active set with the UE. Channel information between Node Bs is transmitted to the first Node B 601 through the FBI field of UL_DPCCH. Since the information transmitted through the FBI field of the UL_DPCCH is not related to the second node B 603 that is not the primary base station, the second node B 603 ignores the information transmitted through the FBI field. The first node B 601 receiving the power offset information to be used for the HI transmitted through the UL_DPCCH or the channel information between the UE and the Node Bs in the active set transmits the HI using the power offset information to be used for the transmitted HI. To determine the power, or to transmit information on the channel environment between the UE receiving the HS_DSCH and the Node Bs in the active area of the UE to the RNC to transmit the HI to the UE 611 as determined by the RNC. do.

In case of transmitting power offset information to be used for HI by using the SSDT codewords of Tables 2 and 3, the transmission period is determined according to the length of the SSDT codeword and the type of SSDT codeword used. The minimum value of the transmission period is when a 2-bit FBI field is used. In this case, as shown in Table 3, when a short SSDT codeword is used, 6 bits should be transmitted. Since the 2 bits per slot are used for the SSDT, a total of 3 slots is required. In addition, the maximum value of the transmission period is when a 1-bit FBI field is used. In this case, as shown in Table 2, when a long SSDT codeword is used, 15 bits should be transmitted. Since 1 bit is used for the SSDT, a required slot is 15 slots, that is, one frame.

The HI transmit power offset value used in the second method of determining the HI transmit power of the present invention is calculated as in Equation 1 below.

Equation 1 is to calculate the transmit power of HI in the soft handover region. When transmitting the HI to the UE 611, as in the HI, an offset according to the number and type of Node Bs in the active set of the UE to the transmission power P for the DPCH before soft handover region, And an offset according to channel environment change between the UE and the Node Bs in the active set to which the UE belongs, Is determined.

In Equation 1, if the UE 611 is located outside the soft handover area, the transmit power of HI is equal to the transmit power for DPCH, P.

Referring to FIG. 8, the following Equation 1 is solved.

FIG. 8 is a diagram illustrating a change in transmit power of a Node B transmitting HI, and illustrates elements necessary for determining transmit power of HI at time 850. In FIG. 8, the 802 curve shows a transmission power of HI to be transmitted by the Node B in consideration of the channel environment between the UE and the Node B even when the UE is located or not in the soft handover area. The 802 curve coincides with the transmit power P for DPCH when the UE is not located in the handover area. In other words, when out of the SHO, the transmit power for the DPCH and the transmit power of the HI become equal. In FIG. 8, the 801 curve is a transmission power for the DPCH of the Node B, which is changed due to the UE being included in the soft handover region t, and is a curve when the transmission power offset according to the present invention is not applied. In addition, the 832 offset of FIG. 8 is a power offset generated due to the number and type of Node Bs added to the UE and the active set of the UE because the UE is located in the soft handover area. The offset 832 is the number of Node Bs in the active set at time 850 in FIG. 8, whether the Node B is controlled by the same RNC as the Node B transmitting HS_DSCH, and the number of Node Bs received by the UE. It is determined by the difference in the reception power of the forward DCH, and has an average of 1 to 3 [dB].

The offset 833 of FIG. 8 is an offset of the forward DCH transmit power generated by the channel environment change between the UE and the Node Bs transmitting the HS_DSCH at time 850 in FIG. 8. The calculation of the 833 offset is a value that is determined by interpreting the common pilot signal of the Node B transmitting the HS_DSCH or by separately interpreting the pilot field of the forward DCH transmitted from the Node B transmitting the HS_DSCH to the UE. A value that depends on the distance between UEs and is inversely proportional to the square of the distance. The 833 offset is a value calculated by the measurement value measured by the UE since the Node B transmitting HI cannot use the TPC received from the UE to determine the transmit power of the HI when the number of Node Bs in the active set is two or more. to be.

In the present invention, the UE calculates an appropriate HI power offset, or information for the HI power offset, and transmits the information to the RNC so that the RNC can use the 802 curve. If the information for the HI power offset is sent to Node B, the Node B sends the HI power offset information to the RNC and then receives the appropriate HI transmit power value calculated at the RNC.

The offset 832 of FIG. 8 depends on the received power of the forward DPCH that the UE receives from the Node Bs in the activity set, and the number and type of Node Bs in the active set. The number of Node Bs in the active set is a value known to the UE, and the type of Node B is a value informed to the UE by the UTRAN or a value known to the UE, and each forward DPCH transmitted by the Node B in each active set Receive power is also a value that can be calculated by the UE.

The process of calculating the 832 offset may include determining a minimum and maximum value of a concatenation gain determined according to the number of Node Bs in the first active set, and then receiving a magnitude of the received power of the forward DCH received from each Node B in the active set. And calculate an offset value of 832 in consideration of the number of Node Bs belonging to the same RNC as the Node B transmitting HS_DSCH among the Node Bs in the active set. As an example of calculating the 832 offset value, a UE receiving an HS_DSCH is located in a handover region, the number of active sets of the UE is 2, and one node B among two Node Bs in the active set of the UE receives an HS_DSCH. If the node B belongs to a different RNC from the transmitting Node B, the 832 offset may have a minimum value when the difference between the received powers received from the two Node Bs is large, and the value is 1 dB. When the values of the received powers received from the two Node Bs are the same, the maximum value is 3dB. Which value is selected between the maximum value and the minimum value of the 832 offset value is the size of the received power of the pilot field of the CPICH or the forward DPCH that the UE receiving the HS_DSCH receives from each Node B in the active set of the UE. Can be calculated in consideration.

The offset 833 of FIG. 8 is a value determined according to a channel environment between the UE and the Node B transmitting the HI, and the channel environment refers to a distance between the UE and the Node B transmitting the HI and fading due to multipath. It is determined by. The 933 offset may be determined in various ways. The first method uses a common pilot channel signal received by the UE, and the second method uses a pilot channel signal of the forward DCH received by the UE. The third method may be a method of using a common pilot channel signal received by the UE and a dedicated pilot signal of the forward DCH.

The first method uses the current WCDMA standard scheme in which the UE measures the size of all common pilot signals received from the base stations in the active set every frame and reports them to the UTRAN. That is, the UTRAN compares the common pilot signals of not only the primary base station transmitting the HS_DSCH but also the secondary base station not transmitting the HS_DSCH, and determines the power offset in HI. same.

The UE measures the size of the common pilot signal of the Node B transmitting the HI every frame and decreases the 933 offset value when the signal size increases, and increases the 833 offset value when the signal size decreases. The initial value of the 833 offset value may be determined based on the size of the common pilot channel signal measured when the UE first enters the soft handover region, and the initial value may be 0 [dB]. When the UE stays in the soft handover region, the offset value increases or decreases according to the change of the common pilot channel signal size measured every frame. As an example of calculating the 833 offset value, if the signal size of the common pilot channel signal measured currently and the signal size of the common pilot channel measured one frame differs by 1 dB, the 933 offset is set to 1 dB or 0.5 dB or other value. Will be decided.

The size of the offset according to the increase or decrease of the signal size of the common pilot channel may be different for each soft handover region, and may be determined by dividing it into a city, a sub-center, and a suburb. For example, the determination of the 833 offset for the distance between the Node B transmitting the HS_DSCH and the UE, which is one of the factors for determining the 833 offset, will be inversely proportional to the fourth or fifth squared distance in the city center. In the case of sub-centers, it is inversely proportional to three squares; in suburban areas, it is inversely proportional to two squares.

In order to improve accuracy in the first method of determining the 833 offset, it may be used to determine the 833 offset by measuring the magnitude of the common pilot signal of another Node B in the active set. The difference between the measured signals of the two common pilot channels is the size of the common pilot signal of the secondary base station (Node B) of the Node B having the largest size of the common pilot signal among other secondary base stations (Node B) that transmits HS_DSCH. It is defined as the difference of the common pilot signal. An example of a method of determining an 833 offset using the difference of the common pilot signal is shown in Table 4 below.

Increase or decrease of common pilot channel signal difference Change in Common Pilot Channel Signal of Node B Transmitting HS_DSCH Offset according to channel environment transformation between UE and Node B transmitting HS_DSCH + has exist Use offset increased from previous offset value none Use the same offset value as the last offset - has exist Use offset reduced from previous offset value none Use the same offset value as the last offset

Table 4 shows a method of determining an offset using a difference of common pilot signals. In Table 4, the difference between the common pilot channel signal is greater than the difference of the common pilot signal measured in the previous frame, indicating that the distance between the Node B transmitting the HS_DSCH and the UE has become farther away or the UE is measuring the active signal. It means that the magnitude of the common pilot signal of another Node B in the set has changed. Therefore, if the signal size of the common pilot signal channel of the Node B transmitting the HS_DSCH is reduced, the UE uses the offset increased from the 833 offset value applied in the previous frame, and the UE B uses the offset of the common pilot channel signal of the Node B transmitting the HS_DSCH. If there is no change, it means that the common pilot channel signal of the Node B that does not transmit the HS_DSCH has changed. The change of the signal of the common pilot channel of the Node B that does not transmit the HS_DSCH has no relation to the setting of the transmit power of HI, and thus the 833 offset value applied to the previous frame is applied as it is.

In the method using the difference between the signal magnitudes of the two common pilot channels, the initial value of the 933 offset may be the initial value measured when the UE first enters the soft handover region. In this case, the initial value may be 0 dB.

A second method of determining the 833 offset is a method of measuring and using the pilot signal of the forward DCH received by the UE.

The method of using the common pilot signal, which is the first method of determining the 833 offset, has a measurement period of one frame and thus may not properly reflect the change in the channel environment when the channel environment is rapidly changing. It is necessary to quickly reflect the change in the channel environment, and when the update period of the SSDT code is fast, the size of the dedicated pilot signal of the forward DCH is measured and used. The method used is the same as the first method of determining the offset 833. That is, if the size of the pilot signal of the forward DCH of the Node B transmitting the HS_DSCH increases, the value of 833 offset is smaller than the offset of 833 which was applied to the previous frame.If the size of the dedicated pilot signal of the forward DCH decreases, the offset of 833 is used. Use a value greater than the 833 offset that was applied to the previous frame. The second method of determining the 833 offset may also use the size of the dedicated pilot signal of the forward DCH received from another Node B in the active set in order to increase the reliability, which is based on the principle of the first method of determining the 833 offset. same.

The third method of determining the 833 offset is to use both the common pilot signals of the Node B and the dedicated pilot signals of the forward DCH in the active set received by the UE. The first method of determining the 833 offset is suitable when the change of the channel environment is small or the update period of the SSDT code is long, and the second method of determining the 833 offset is the change period of the channel environment or the update period of the SSDT code It is suitable when is short. Therefore, the advantages of each method can be combined and used in the third method. An example of the third method of determining the 833 offset is as described below. For the purpose of understanding the present invention, the length of the SSDT code is 10 bits, the length of the D-field of the FBI field is 2 bits, and the relative power offset is used. Assume that the update period of is 5 slots.

In the example of the third method, the UE measures the pilot signal of the forward DCH in every slot for 5 slots, calculates the 933 offset by weighting it from the most recently measured value, and then applies relative power to HI transmission. The offset is calculated and transmitted to the Node B transmitting the HS_DSCH over the next 5 slots. After the second relative power offset is transmitted twice, the third relative power offset is transmitted to the Node B transmitting the HS_DSCH by determining the relative power offset with the 833 offset determined by the size of the common pilot signal. The reason for the above is to correct the relative power offset in consideration of the case where the actual number of pilot bits transmitted on the forward DCH is smaller than the number of bits of the common pilot channel, so that the actual channel environment cannot be properly reflected. In this case, the period of correcting the power offset using the common pilot channel may be changed to a period previously promised by the upper layers of the UE and the Node B.

The actual offset value that the UE sends to the Node B transmitting the HS_DSCH to determine the transmit power offset of the HI for the DCH transmit power is dependent on the UE receiving the HS_DSCH and the number and type of Node Bs in the active set of the UE. The sum of the offset 832 of FIG. 8 and the 833 offset value of FIG. 8 according to the channel environment change between the UE and the Node B transmitting the HS_DSCH. If the sum of the 832 offset and the 833 offset is defined as an HI transmit power offset transmitted by the UE to set a transmit power of HI, the HI transmit power offset may be set as shown in Table 5 below.

HI Transmit Power Offset for HS_DSCH Short code 0.5 dB 00000 1 dB 01001 1.5 dB 11011 2 dB 10010 2.5 dB 00111 3 dB 01110 3.5 dB 11100 4 dB 10101

In Table 5, the code used is a short code used for 1-bit FBI among SSDT ID codes. In Table 5, the HI transmission power offset is a UE receiving an HS_DSCH and a Node B in an active set of the UE. It was determined by considering the offset of 1 ~ 3 [dB] by the type and number of and the offset to the change of channel environment. Table 5 is an example of the HI transmit power offset determined by the present invention. Among the eight offset values shown in Table 5, the HI transmission power offset to be transmitted to the Node B transmitting the HS_DSCH may be determined by adding the 832 offset and the 933 offset of FIG. 8, and then rounded to select the nearest value. It was made. Receiving the HI transmit power offset, the Node B uses the HI transmit power offset during the HI transmit power update period or uses the initial value for transmitting the first slot transmitting the HI and then transmits the TPC transmitted by the UE from the next slot. It is also possible to adjust the transmit power of HI using.

In the method for transmitting the information about the transmit power of the HI to the Node B, if the UE transmitting the information about the transmit power of the HI directly determines the HI transmit power offset, the information about the HI transmit power is the HI transmit power offset If the RNC determines the HI transmission power, the information on the HI transmission power transmitted by the UE may be information for determining the HI transmission power.

The first method is for the UTRAN (especially RNC) to determine the transmit power of the HI for HS_DSCH in consideration of feedback information transmitted from the UE and the number and type of Node Bs in the active set of the UE known to the RNC. The method uses the UE to determine the HI transmit power offset using information such as the number and type of Node Bs in the active set of the UE and information measured by the UE, e.g., common pilot signal sizes of the Node Bs in the active set. It informs B or RNC, and determines the transmission power of HI according to the said value.

There may be a third method in addition to the first method and the second method of determining the transmit power of the HI. The third method of determining the transmit power of the HI is that the UTRAN (particularly RNC) does not use feedback information from the UE. The value you know is used to determine the transmit power of the HI. The information used by the RNC in determining the transmit power of HI includes the number and type of Node Bs in the active set of the UE receiving the HS_DSCH, and the common pilots of the Node Bs in the active set periodically reported by the UE through the UL_DPDCH. The magnitude of the signal. The advantage of the third method is that since the UE does not need to receive feedback information using UL_DPCCH, the UE does not need to calculate information or an offset value for the transmit power of HI and the complexity of UE hardware due to not transmitting the feedback information. Will decrease.

9 is a diagram illustrating a receiver structure of a terminal (UE) capable of receiving in a multipath according to an embodiment of the present invention. The multipath is a word that refers to a path in which a Node B transmission signal is directly received by the UE or indirectly received by an obstacle or the like when the UE is not located in the soft handover area, and the UE is in the soft handover area. If is located at, refers to the paths received from the Node Bs in the active set to the UE.

The UE receives the RF signals transmitted from the Node Bs in the active set of the UE through the antenna 901 of FIG. 9, and then bases the RF signals carried on the carrier through the RF unit 902. Convert to a signal in the middle frequency band. The output of the RF unit 902 is provided to the demodulator 903 and demodulated, and then input to the demixer #n 930 from the descrambler # 1 (Descrambler) 910 to perform descramble. Rough The number of demixers is a value determined by how many forward scrambling codes the UE can simultaneously demix. This may vary from manufacturer to manufacturer. In this case, the forward mixed code is a code used to distinguish each node B or a base station in the W-CDMA scheme. In FIG. 9, in order to facilitate understanding of the present invention, the demixer # 1 910 is used to demix a signal of the Node B # 1 that does not transmit the HS_DSCH in the active set, and the demixer #n (930). Suppose is used to demix the signal of Node B #n transmitting HS_DSCH.

The output from the demixer # 1 910 is input to the despreader # 1 911 to distinguish each downlink channel by multiplying the Walsh code corresponding to the Walsh code multiplied by each downlink channel in the Node B transmitter. Do the work. The Walsh code used to distinguish the channels is referred to as an Orthogonal Variable Spreading Factor (OVSF) code in the W-CDMA scheme, and its length is determined according to the data rate of each channel. The output of the despreader # 1 911 may be a downlink common channel signal, a downlink dedicated channel signal, and a downlink common pilot channel signal. The downlink common channel signal may be a broadcasting channel through which Node B system information is transmitted, a paging channel for transmitting signaling information to a UE, or a forward access channel. have. In addition, the downlink dedicated channel signal refers to a dedicated channel transmitted by the Node B # 1 to the UE.

The common pilot channel output from the despreader # 1 911 is input to the common channel pilot estimator 912 to adjust the phase change of the UE received signal and the magnitude of the common pilot signal according to the change in the channel environment between the Node B # 1 and the UE. It allows you to estimate. The phase of the transmission signal of the Node B # 1 estimated by the common channel pilot estimator 912 is input to the phase compensator 913 to compensate the phase of the downlink dedicated channel received by the UE from Node B # 1, and the phase The magnitude of the common pilot signal estimated by the compensator 913 is input to the downlink power control command generator 950 to be data for generating downlink power command information or downlink channel information.

The demultiplexer 914 of FIG. 9 distinguishes a downlink dedicated data physical channel (forward DPDCH) and a downlink dedicated data control channel (forward DPCCH) from a downlink-dedicated channel signal outputted with phase compensation from the phase compensator 913. Output The downlink dedicated channel is separated by passing through the demultiplexer 914 in a time division multiplexed form of the forward DPDCH and the forward DPCCH. The output of the demultiplexer 914 is a downlink dedicated channel data field, HI, TFCI, dedicated channel pilot, and TPC. The downlink-only data field is input to the deinterleaver 915 and deinterleaved, and then is input to the decoder 916 to be converted into data before channel encoding and transmitted to the upper layer of the UE. The dedicated channel pilot, which is the output of the demultiplexer 914, is input to the dedicated channel pilot estimator # 1 917 of FIG. 9 to become data for measuring the size of the dedicated channel pilot signal. The dedicated channel pilot signal magnitude estimated by the dedicated channel pilot estimator # 1 917 is input to the downlink transmission power control command generator 950 of FIG. 9 to become downlink transmission power command information or downlink channel information. . The TPC, which is the output of the demultiplexer 914, is an uplink power control command transmitted by Node B # 1 to control uplink signal power of the UE, and is used as an uplink power control command transmitted by the UE and a downlink power control command. It is input to the generator and becomes data for generating downlink transmission power command information.

Meanwhile, the demixer 930 of FIG. 9 performs a demixing process of the downlink signal transmitted from the node B # n, and the operation principle is the same as that of the demixer # 1 910. The signal output from the demixer #n 930 is input to the despreader #n 931, and is divided into a common pilot channel, a downlink dedicated channel signal, a downlink common channel signal, and a downlink shared channel signal. The operation principle of the despreader #n 931 is the same as that of the despreader # 1 911. The common pilot channel output from the despreader #n 931 is input to the common channel pilot estimator #n 932 to output a phase change according to the channel environment from the node B #n to the UE using a phase compensator 933. The data is input to the downlink power control command generator 950 to generate downlink power command information or downlink channel information. The principle of the common pilot channel estimator #n 932 is the same as the common channel pilot estimator # 1 912. The downlink dedicated channel signal output from the despreader #n 931 is separated into a TPC, a dedicated channel pilot, a TFCI, a downlink dedicated channel data field, and an HI through a phase compensator 933 and a demultiplexer 934.

The phase compensator 933 has the same principle as the phase compensator 913, and the demultiplexer 934 has the same function as the demultiplexer 914. The downlink-only data field is input to the deinterleaver 935, deinterleaved, and then input to the decoder 936 to be converted into data before channel encoding and transmitted to the upper layer of the UE. The dedicated channel pilot output from the demultiplexer 934 is input to the dedicated channel pilot estimator #n 937 of FIG. 9 to be data for measuring the size of the dedicated channel pilot signal, and the dedicated channel pilot estimator #n ( The principle of 937 is the same as the dedicated channel pilot estimator # 1 917. The dedicated channel pilot signal magnitude estimated by the dedicated channel pilot estimator #n 937 is input to the downlink power control command generator 950 of FIG. 9 to become downlink power command information or downlink channel information. .

The TPC, which is the output of the demultiplexer 914, is an uplink power control command transmitted by Node B # n to control uplink signal power of the UE, and is used as an uplink power control command transmitted by the UE and a downlink power control command. It is input to the generator and becomes data for generating downlink transmission power command information. The downlink common channel signal output from the despreader #n 931 may be a broadcasting channel, a forward access channel, and the like, and the broadcasting channel transmits system information, and the forward access channel is a higher layer of Node B or The signaling information transmitted from the upper layer of the mobile communication network to the UE is transmitted. The downlink shared channel, which is the output of the despreader #n 931, is inputted to the deinterleaver 938 and deinterleaved, inputted to the decoder 939, decoded, and then transmitted to the upper layer of the UE. The downlink shared channel is a channel through which only user data is transmitted. The operation of the deinterleaver 938 is the same as that of the deinterleaver 915 and the deinterleaver 935, and the operation of the decoder 939 is performed by the decoder ( Operation 916 and decoder 936 are the same.

The downlink power control command generator 950 of FIG. 9 receives a signal from a Node B # 1 when a mobile UE reaches a soft handover area and receives a signal from a Node B as well as an existing Node B. A downlink dedicated channel (forward DPCCH) receives a TPC, a dedicated channel pilot signal size, a common pilot signal size, and receives a TPC, a dedicated channel pilot signal size, and a common pilot signal size received from the Node B # 2; Generates HI power control information, TFCI transmission power control information for downlink shared channel linked thereto, and downlink channel information to which the HS_DSCH is transmitted.

10 is a diagram showing the structure of a transmitter of a UE according to an embodiment of the present invention.

Referring to FIG. 10, the downlink dedicated channel and HI power control information and the downlink shared channel TFCI power control information output from the 950 downlink power control command generator of FIG. 9 are included in the downlink power control command generator 1011 of FIG. 10. ) Is converted into a codeword indicating a downlink dedicated channel power control command and TFCI transmission power offset information or downlink channel information. The downlink dedicated channel power control command is transmitted through the TPC field of UL_DPCCH and is broadcast to all Node Bs in the active set of the UE. The downlink shared channel TFCI and HI transmit power offset related information or downlink channel information is a value determined by the downlink transmit power control command generator 1350 of FIG. 13. The uplink transmit power control command generator 1011 outputs a TFCI for downlink shared channel and a codeword indicating HI transmit power offset and downlink channel information to the S field among the FBI fields of UL_DPCCH, and outputs the downlink dedicated channel to the TPC field of UL_DPCCH. Send a power control command. The multiplexer 1016 of FIG. 10 receives a value to be input to the FBI field 1012 and a value to be input to the TPC 1013 from the uplink power control command generator 1011, and pilots at the physical layer of the UE. In operation 1014, the TFCI 1015 is input and multiplexed to generate UL_DPCCH data. Data of the UL_DPCCH is input to the spreader 1017 of FIG. 10 and spread to the OVSF code to be used for the UL_DPCCH.

The multiplier 1017 spreads the multiplier 1020 to multiply the transmit power gain of the UL_DPCCH by the multiplier 1020, and then inputs the summer 1005 to add the UL_DPDCH. The UL_DPDCH is interleaved in the interleaver 1003 after the user data 1001 for the UL_DPDCH is encoded in the encoder 1002, and spread in an OVSF code suitable for a transmission rate in which the UL_DPDCH is transmitted in the spreader 1004. After spreading in the spreader 1004 and multiplied by a transmit power gain that adjusts the transmit power of the UL_DPDCH in the multiplier 1021, it is input to the summer 1005 and summed with the UL_DPCCH. The UL_DPDCH and UL_DPCCH input and summed into the summer 1005 are mixed with the scrambling code used by the UE in the multiplier 1021 for UL_DCH. The mixed signal is input to the modulator 1007, modulated, and then multiplied by a carrier in the RF unit 1008 to be broadcast to the Node B through the antenna 1010.

11 is a diagram showing the structure of a Node B receiver according to an embodiment of the present invention.

Referring to FIG. 1, a signal of a UE received through the antenna 1101 of FIG. 11 is changed into a signal of an intermediate frequency or a base frequency band by an RF device 1102, and then demodulated by a demodulator 1103, and a demultiplexer. Inversely at 1104. The scrambling code used for the demixing is the same scrambling code used by the UE in the multiplier 1006 of FIG. 10. The scrambling code enables the Node B to distinguish signals from several UEs. The signal output from the demultiplexer 1104 is input to the despreader 1105 of FIG. 11 and divided into UL_DPCCH and UL_DPDCH.

The UL_DPCCH output from the despreader 1105 is input to the demultiplexer 1106 and divided into pilot, TFCI, FBI, and TPC. The uplink dedicated channel pilot is input to the dedicated channel pilot estimator 1107 to estimate a phase change of a signal according to a channel environment from the UE to the Node B and a magnitude of a signal of the uplink dedicated channel pilot. The estimated phase change value is input to the phase compensator 1110 of FIG. 11 to compensate for the phase of the UL_DPDCH output from the despreader 1105. That is, since the UL_DPDCH is received by the Node B through the same channel environment as the UL_DPCCH, the UL_DPDCH according to the change of the channel environment between the UE and the Node B is an estimated phase change value output from the dedicated channel pilot estimator 1107. It is possible to compensate the phase distortion of the.

The dedicated channel pilot signal magnitude output from the dedicated channel pilot estimator 1107 is input to the uplink transmission power control command generator 1108 and becomes data for generating a TPC that Node B uses to control uplink transmission power. On the other hand, the output FBI of the demultiplexer 1106 is input to the downlink channel transmission power controller 1109 and then used to generate a downlink dedicated channel power control command. Also, the output TPC of the demultiplexer 1106 is input to the downlink transmission power controller 1109 and then used to generate a downlink shared channel power control command.

The downlink transmission power controller 1109 generates a command for controlling the transmission power of the downlink shared channel TFCI and HI using the FBI information input from the demultiplexer 1106, wherein the FBI information is used to transmit the TFCI and HI. It may be power offset and downlink channel information. When the FBI information is configured as described above, the TFCI and HI transmission power offset or downlink channel information are transmitted by being encoded with an SSDT ID code or another code, and thus used by the downlink transmission power controller 1109 after being decoded. The downlink channel information is not directly used by the Node B, but is transmitted to the UTRAN to be a material for determining the power offset to be used for the HS_DSCH. Thereafter, the uplink-only data channel signal output from the phase compensator 1110 of FIG. 11 is input to the deinterleaver 1111 and deinterleaved, and then decoded by the decoder 1112 and transmitted to the upper layer of the Node B.

12 is a structure of a Node B transmitter according to an embodiment of the present invention.

In FIG. 12, the user data to be transmitted to the forward DPDCH is encoded through the encoder 1201, and then interleaved by the interleaver 1202 and input to the multiplexer 1205. The multiplexer 1205 is a TPC for controlling the transmission power of the UL_DCH output from the TFCI 1204, the pilot 1203, the uplink transmission power control command generator 1206, the forward DPDCH output from the interleaver 1202, HI 1230 and TFCI are received as inputs and multiplexed to generate forward DCH. The uplink transmit power control command generator 1206 is the same device as the uplink transmit power control command generator 1108 of FIG. 11, and after setting the TPC using the signal size of the dedicated pilot channel of UL_DPCCH, the forward DCH Transmit on forward DPCCH. The channel gain set for adjusting the transmit power of the forward DCH in the multiplier 1232 is input to the spreader 1207 and spread to the OVSF code used by the forward DCH. Is multiplied and input to summer 1220. The channel gain set for adjusting the transmit power of the forward DCH is set by an uplink dedicated channel power control command output from the uplink transmit power controller 1109 of FIG. 11, and the transmit power of the HI 1230 is shown in the figure. It is determined by the transmission power output from the uplink transmission power controller 1109 of 11 or the transmission power transmitted by the RNC.

The encoder 1211 of FIG. 12 is an encoder for encoding HS_DSCH data transmitted from the Node B to the UE. The encoded HS_DSCH is input to the interleaver 1212 and interleaved, and then spread in the spreader 1213 with an OVSF code for the HS_DSCH. The signal spread from the spreader 1213 is input to the multiplier 1233, multiplied by the channel gain for transmission power control of the HS_DSCH, and input to the summer 1220.

The downlink common channels 1215 of FIG. 12 are input to a multiplier 1230 and multiplied by a channel gain suitable for the common channels and input to a summer 1220. In this case, the downlink common channel 1215 may include a primary common control physical channel through which a broadcasting channel is transmitted, and a secondary common control physical channel through which a forward access channel and a paging channel are transmitted. And a common pilot channel. The dedicated user channel 1217 of FIG. 12 is dedicated channels transmitted to other users in the node B. After encoding, interleaving, and spreading, the multiplier 1231 multiplies the channel gains suitable for the dedicated channels. And input to summer 1220.

The summer 1220 of FIG. 12 receives the downlink common channel, the downlink-dedicated channels, and the downlink shared channel as inputs, and adds them to the multiplier 1221. The multiplier 1221 multiplies the scrambling code used by the node B and outputs the multiplier to the modulator 1222. The modulator 1222 receives the downlink signals of the mixed node B as an input, modulates the downlink signals, and outputs the modulated signals to the RF device 1223. The RF device 1223 uploads downlinked signals of the modulated Node B to a carrier and transmits them to the UEs in the Node B through the antenna 1225.

According to the present invention, a method for determining a power offset value when transmitting HI based on the number of cells transmitting HI and the number of cells not transmitting HI, and when UE determines the power offset value, the UE measurement information. Details of the method for transmitting to the Node B will be described in detail together with the drawings.

FIG. 13 is a diagram illustrating the concept of the present invention, and to facilitate understanding of the present invention, a primary base station (Node B) 1305 and a secondary base station (Node B) 1335 belonging to different RNCs in an active set of UEs. It is assumed that the number of cells connected at each base station is N and M, respectively. Here, the primary base station is a primary Node B 1305 of FIG. 13, which is a base station transmitting an HS_DSCH and a corresponding forward DPCH to the UE 1311, and the secondary base station is the secondary of FIG. 13. As the Node B 1335, the base station transmits only a downlink signal (forward DCH) to the UE 1311 due to the position shift of the UE 1311. When the same information is being transmitted in the RNC, the maximum number of cells that can be connected to the UE can be specified as eight, which means that the M and N values are integers from 0 to 7, respectively. . In this case, the power offset of HI may be determined based on M and N values. Here, M value is defined as the number of cells that do not transmit the HS_DSCH and N value is defined as the number of cells that transmit the HS_DSCH. In addition, the cells transmitting the HS_DSCH may be cells within an active set in the RNC 1302. M and N can be known by the RNC and the UE. Thus, the power offset is determined by the RNC or the UE.

If the power offset determiner is an RNC, SRNC is possible. In this case, the SRNC uses a Radio Link Setup / Addition message to obtain information about M and N. That is, the SRNC may determine a cell for transmitting the HS_DSCH and then set a HI transmission power offset through a Radio Link Setup / Addition Request message. In this case, if the corresponding cell does not support the HSDPA service, the SRNC is informed of the corresponding information through a Radio Link Setup / Addition Response message. Thereafter, the SRNC may control the HI transmit power by determining an adjusted power offset for optimizing the HI transmit power in a transmission environment and transmitting the adjusted power offset to a cell supporting the HS_DSCH.

In order to deliver information on whether a specific cell in the active set supports the HSDPA service to the SRNC, in the present invention, a Radio Link Setup Response message may be configured as shown in Tables 6 and 7 below. Table 6 below shows an example of a Radio Link Setup Response message between RNC and Node B, and Table 7 below shows an example of a Radio Link Setup Response message between RNC and RNC.

In the present invention, a technique for transmitting the power offset value for the HI transmission from the RNC to the Node B will be described in detail with reference to the accompanying drawings. The power offset value determined based on the M value and N should be transmitted to the node B.

The method for transmitting the determined power offset value may use an NBAP message, which is a signal message between the Node B and the RNC. A radio link setup message may be used as a message capable of transmitting a power offset among the NBAP messages.

Table 8 below shows a structure of a Radio Link Setup message for setting a power offset value for HI. In Table 8, PO4 represents a reference power offset for HI transmission.

The number of cells transmitting the HS_DSCH can be changed whenever the active set is changed by the UE's handover operation. In this case, the N value and the M value may be changed, and at this time, a power offset value for HI may be newly determined based on the changed N value and M value. At this time, there is a method of transmitting this value to the Node B using a frame protocol shown in FIG. 15 and a method of transmitting using a Radio Link Reconfiguration message among NBAP messages. Node Bs to receive the power offset correspond to Node Bs including a specific cell transmitting HS_DSCH.

Table 9 below shows a structure of a Radio Link Reconfiguration message to which the power offset value is added. In Table 9, PO4 represents a power offset value of transmit power for HI transmission.

FIG. 14 is a diagram illustrating the concept of the present invention and shows a data frame transmission of a UE and a power offset transmission path from an RNC to a Node B for better understanding of the present invention. It is assumed that there are RNC A 1402 and RNC B 1404 belonging to different RNS, and are connected to different Node Bs, respectively. In this case, only one 1411 of the downlink information transmitted from the Node B to the UE 1431 transmits two pieces of information 1421, the forward DCH and the HS_DSCH, and the remaining cells 1412, 1413, and 1414 are the forward DCH. Only (1422, 1423, 1424) is sent. This is briefly summarized in FIG. 18.

The first method described in FIG. 18 is to transmit a power offset to the Node B 1405 including a cell in which the HS_DSCH is transmitted. That is, a method related to the case where the RNC 1402 connected to the Node B including the cell in which the HS_DSCH is transmitted is the SRNC of the UE will be described. FIG. 22 is a diagram illustrating a structure of a message in which an RNC transmits an HI power offset to a Node B. FIG. As shown in FIG. 22, the RNC may transmit to node B by adding a power offset to spare 2201 of the HS_DSCH control frame.

In step 1801 of FIG. 18, the SRNC transmits a control frame including HI power offset information. The structure of the control frame is shown in FIG. In the control frame transmission scheme proposed by the present invention, the RNC 1402 in FIG. 14 transmits all Node Bs including a cell for transmitting HI. That is, a control frame is transmitted to all node Bs of the RNC connected to the cell transmitting HI, that is, the node B 1405 and the node B 1406 of FIG. 14, so that all cells 1411, 1412, 1413) to receive the power offset. Another method of transmitting the HI power offset information to the Node B is to transmit the HS_DSCH data frame only to the cell 1411 transmitting the HS_DSCH in the RNC 1402 of FIG. 14.

FIG. 17 illustrates a structure of a DSCH data frame when a power offset is transmitted from the RNC to a Node B using a data frame. 17 shows an example of a method of adding a power offset to a DSCH data frame.

FIG. 17 may include power offset information in a data frame and fill the power offset in an empty space of a header, and transmit the power offset information to the node B. However, the adjacent power offset 1702 is a data power offset, not a TFCI power offset. 17 illustrates a method of adding a power offset to spare bits parallel to the TFI bits. In this case, since the spare bit is 3 bits, the number of power offsets that can be transmitted from the RNC to the Node B can be eight.

As another method of transmitting a power offset from the RNC to the NodeB, there are a method using the control frame and both methods using the d data frame.

In step 1802 of FIG. 18, the node B receives a control frame including a power offset transmitted by the SRNC in step 1801 of FIG. 18. In this case, when receiving a data frame instead of a control frame, only the Node B 1405 including the cell 1411 transmitting the HS_DSCH receives the data frame.

In step 1803 of FIG. 18, the cells in the Node B receive HI power offset information. When receiving a data frame in step 1702, only the cell 1411 transmitting the HS_DSCH receives the power offset.

Finally, in step 1804 of FIG. 18, cells corresponding to each radio link transmit HI using the HI power offset of the node B. FIG.

19 illustrates a method for a case where the RNC 1402 connected to a Node B including a cell for transmitting the HS_DSCH is a DRNC. The SRNC transmits a power offset to the DRNC by using a control frame. FIG. 20 is a diagram illustrating a structure of a control frame when the SRNC transmits a power offset using a control frame to the DRNC. The control frame refers to a radio frame used when transmitting control information from the SRNC to the DRNC. A control frame cyclic redundancy check (CRC) is transmitted to a header portion of the control frame in addition to a frame type, that is, a region indicating whether a control frame or a data frame is present. do. The control frame CRC is defined as a 7-bit empty space as in the following 4-bit empty space for extra data transmission. Another way in which the SRNC transmits a power offset to the DRNC is a method of adding power offset information to the HS_DSCH data frame transmitted from the SRNC to the DRNC. 21 is a diagram illustrating an HS_DSCH data frame structure to which the power offset is added. As shown in FIG. 21, the power offset value may be transmitted in parallel with the Common Transport Channel Priority Indicator (CmCH-PI) of the HS_DSCH data frame. Referring to FIG. 21, a header portion added when an HS_DSCH data frame is received at a base station has a 4-bit empty space 2101 for extra data transmission, such as 2102, which is an empty space of the data portion. That part is filled with the power offset for HI.

In step 1901 of FIG. 19, the SRNC 1404 transmits a control frame or data frame to the DRNC 1402. In step 1902, the DRNC 1402 transmits a control frame or a data frame to the Node Bs 1405 and 1406. In step 1903, the Node B receives an HI power offset within a control frame or data frame. Finally, in step 1904, the Node B transmits HI to the UE in accordance with the received power offset.

In applying the power offset to the Node B, the following describes a method of differently applying the power offset by using a signal message transmitted from the UE. One example of using a signal message received from the UE is a method using SSDT. SSDT is site selection diversity transmit power control (TPC), which enables faster and more flexible handover by applying macro diversity connection sum at the connection sum point. At this time, each cell transmitting the HI is given a temporary identifier, and the UE in the SHO region periodically transmits primary cell information to the base station in the active set through the uplink FBI region. The primary cell is selected as a cell in which the UE receives the strongest signal. Accordingly, Node Bs that transmit HI may apply different offsets by distinguishing a case where the corresponding cell is a primary from other cases. There are three ways to apply the power offset.

In the first method, the power offset value received from the SRNC in the above embodiment is used as it is, and in the case of non-primary (hereinafter referred to as "non-primary") There is a method of transmitting by adding a constant power offset value from the power offset. For example, if the constant power offset value is 3dB, when the power offset value received from the SRNC is 5dB, each cell transmits HI at a power offset of 5dB when the primary is primary, and non-primary (non-primary). primary) transmits HI with a power offset of 8 dB.

Alternatively, the power offset value received from the SRNC may be used in the case of non-primary, and may be weakly transmitted by a predetermined power offset value in the case of the primary. Finally, only the primary can maintain the power offset.

As described above, the present invention performs power control on HI transmitted to a UE located in a soft handover area, and provides a power offset by the power control, thereby continuously providing HSDPA service without interruption even during handover. It works. In addition, there is an effect that can accurately deliver HI to the UE located in the soft handover area.

Claims (4)

A predetermined movement located in a soft handover area with a second base station adjacent to the first base station among the plurality of mobile terminals in a first base station of a mobile communication system providing a high speed forward packet access service to a plurality of mobile terminals; In the method for performing a power control for the indicator indicating the presence or absence of packet data according to the fast forward packet access service transmitted to the terminal, Transmitting, by the predetermined mobile terminal, channel environment information with the first base station and channel environment information with the second base station to the first base station; The first base station determines the power offset of the indicator transmitted to the predetermined mobile terminal based on the channel environment information from the predetermined mobile terminal, and adds the power offset to the power strength for transmitting the packet data. The method comprising the step of transmitting. The method of claim 1, The channel environment information may include the number of base stations supporting the fast forward packet access service among the base stations in an active state corresponding to the predetermined mobile terminal and the number of base stations not supporting the fast forward packet access service. Way. A predetermined movement located in a soft handover area with a second base station adjacent to the first base station among the plurality of mobile terminals in a first base station of a mobile communication system providing a high speed forward packet access service to a plurality of mobile terminals; In the method for performing a power control for the indicator indicating the presence or absence of packet data according to the fast forward packet access service transmitted to the terminal, The predetermined mobile station measures channel environment information with the first base station and channel environment information with the second base station, and determines the power offset of the indicator transmitted from the first base station based on the channel environment information. Transmitting to the first base station; Receiving, by the first base station, the power offset of the indicator from the predetermined mobile terminal, and adding the power offset to the power strength for transmitting the packet data to transmit the indicator. . The method of claim 3, The channel environment information may include the number of base stations supporting the fast forward packet access service among the base stations in an active state corresponding to the predetermined mobile terminal and the number of base stations not supporting the fast forward packet access service. Way.