WO2004030304A1

WO2004030304A1 - A open loop power control method for downlink common channels in cdma system

Info

Publication number: WO2004030304A1
Application number: PCT/CN2002/000746
Authority: WO
Inventors: Sheng Liu; Baijun Zhao
Original assignee: Utstarcom (China) Co., Ltd.
Priority date: 2002-09-30
Filing date: 2002-10-23
Publication date: 2004-04-08
Also published as: CN1487683A; AU2002344524A1; CN100452674C

Abstract

The present invention relates to a open loop power control method for downlink common channels in the CDMA (code division multiple address) system, including the following steps: distinguish the downlink common channels which diplex bearing specific logical channels, and judge the transmission format combination frame by frame to the downlink common channels beared the specific logical channels; according to the types of the transmission format combination of current wireless frame, control transmission power of wireless frame of downlink common channels which only bears specific logical channel frame by frame. In accordance with the invention disclosed open loop power control method for downlink common channels, utilizing the required powers and characteristics of different logical channels in the public downlink channels, proposes the power control and its methods of specific logical channels, improving the performance of the downkink channels and the utilization rate of wireless resources.

Description

Downlink in code division multiple access system

Common channel open-loop power control method TECHNICAL FIELD

The present invention generally relates to the field of communication technology, and more particularly, the present invention relates to an open-loop power control method for a downlink common channel in a code division multiple access (CDMA) communication system. Background technique

A code division multiple access (CDMA) system is a typical interference-limited system. In a CDMA system, users share the same frequency, and there are non-ideal correlation characteristics between the spreading codes of users. The useful power of any user will become interference to other users. The size of the user ’s transmit power directly affects the total capacity of the system. Therefore, power control technology is an important means to reduce inter-channel interference in CDMA systems. Has been widely used. Power control is divided into uplink power control and downlink power control according to the direction; according to different control methods, it is divided into two categories: closed-loop power control and open-loop power control. Among them, the closed-loop power control is performed by the receiving end comparing the received signal interference ratio (SIR) with its target value, and the resulting power control command is fed back to the transmitting end through the reverse link for power control, so it is only applicable to There is a dedicated channel to the wireless link; the open-loop power control does not require a bidirectional channel, it is directly controlled by the sender according to a certain strategy for its transmit power. For a common type channel with only one-way links, its power control can only be performed in an open-loop manner. Compared with closed-loop power control, the open-loop power control has a lower control rate and control accuracy.

In the wireless interface of the code division multiple access communication system, from the perspective of different protocol layers, the channels carrying various services of the user can generally be divided into three types, that is, logical channels, transmission channels, and physical channels. The logical channel directly carries user services, and the transmission channel is a service provided by the physical layer for the MAC (Media Access Control Layer). It is divided into a dedicated channel and a common channel according to whether the transmission is dedicated information for one user or public information for all users. Two categories: Physical channels are the ultimate manifestations of various types of information transmitted over the wireless interface. Each channel that uses a specific carrier frequency, spreading code, and relative phase and time of the carrier can be understood as a specific type of physical channel. The downlink physical channels in the 3GPP wideband code division multiple access WCDMA system can be divided into: downlink dedicated physical channels and downlink common physical channels. The downlink common physical channel includes: a common pilot channel (CPICH), a synchronization channel (SCH), a paging indicator channel (PICH), an access indicator channel (AICH), and a common control physical channel (CCPCH). The CCPCH physical channel is divided into a first (basic) common control object channel (P-CCPCH) and a second (secondary) common control physical channel (S-CCPCH) according to different transmission channels carried.

In a WCDMA system, the power of each downlink common physical channel is related to network planning parameters such as cell capacity and coverage, and is generally determined by the network planning process and transmitted at a relatively fixed power level.

When the physical layer provides service to the MAC, the S-CGPCH is used to carry two types of transmission channels: a forward access channel (FACH) and a paging channel (PCH). S-CCPCH can either carry FACH or PCH transmission channels separately, or multiplex both transmission channels at the same time. Among them, the PCH transmission channel is used to carry a logical channel PCCH (paging control channel), and the FACH transmission channel is used to carry a BCCH (broadcast control channel), CCCH (common control channel), CTCH (common service channel), DCCH (dedicated control channel) ), DTCH (dedicated service channel) and other logical channels. For a detailed description of these channels and their multiplexing modes, please refer to the 3GPP specifications 3GPP TS 25.211, 3GPP TS 25.321, 3GPP TS 25.301, 3GPP TS 25.302, and other documents. For the usage of S-CCPCH, please refer to the 3GPP specifications TS 25.331, TS 25.302, TS 25.304 and other documents.

Among the logical channels carried by the FACH transmission channel carried by the S-CCPCH physical channel, the DTCH and DCCH logical channels exist only in the CELL-FACH state of the RRC (Radio Resource Control Layer) connection mode (RRC Connected Mode). Regarding the RRC information For a detailed description of the commands and their different modes and states, please refer to the 3GPP specifications TS 25.331 and other documents. One FACH transmission channel may carry DTCH and DCCH logical channels of different user equipments (UEs), and different users are distinguished by the UE-ID field of the MAC (Media Access Control) header of the FACH transmission channel. Among them, the DCCH logical channel is used to carry RRC signaling of the UE whose RRC connection is activated in the CELL-FACH state, and the DTCH logical channel is used to carry small amount of user data. In the CELL_FACH state, no dedicated physical channel is allocated to the UE, but RACH and FACH channels are used to transmit signaling information and a small amount of user plane data.

Specifically, in WCDMA, when a UE in an idle mode is triggered to leave the idle mode, the UE sends an RRC connection request message to the network. When the UE receives an acknowledgement message for the RRC connection establishment, it establishes an RRC connection. The UE enters the CELL_DCH or CELL_FACH state in the UTRAN (UMTS Terrestrial Radio Access Network) connection mode: If the RRC connection uses a dedicated transmission channel, it enters the CELL_DCH state; if a common transmission channel is used, Then enter CELL_FACH state. The CELL-FACH state is an important state next to CELL-DCH. Compared with the case where the Radio Network Controller (RNC) in the CELL-DCH state needs to allocate a pair of dedicated physical channels for an RRC connection, the CELL-FACH state The downlink of multiple UEs can be time-multiplexed into one S-CCPCH, and the uplink transmits data or signaling through a random access channel (RACH).

In the prior art, as one of the downlink common physical channels, the S-CCPCH channel does not perform power control. In order for all users in the cell to receive it correctly, all S-CCPCH channels can only be high enough. Only relatively fixed power transmission can ensure coverage of the entire cell. However, in this case, when the number of UEs in the CELL-FACH state reaches a certain number, the resulting interference will greatly affect the system performance, thereby offsetting the small data volume caused by the use of RACH / FACH. benefit. Summary of the invention

Therefore, an object of the present invention is to perform open-loop power control on a code division multiple access downlink common channel to improve radio resource utilization. An open-loop power control method for a downlink common channel in such a code division multiple access system proposed by the present invention includes the following steps: distinguishing a downlink common channel multiplexed with a dedicated type logical channel; The downlink common channel determines the transmission format combination of the downlink common channel on a frame-by-frame basis; and according to the transmission format combination type of the current radio frame, frame-by-frame control of the transmission power of the downlink common channel radio frame carrying only a dedicated type of logical channel. Type of logical channel: control the transmit power of the downlink: co-channel radio frame so that the transmitted downlink power is exactly what the particular user can receive, thereby reducing interference to other users caused by using full power transmission . By performing power control on the downlink common channel in this case, the radio resource utilization rate is improved. For this reason, the present invention aims to reduce the transmission power of the S-CCPCH physical channel when the downlink of multiple UEs is time-multiplexed in the CELLJFACH state by multiplexing one S-CCPCH physical channel. The RRC connection occupies limited channel resources to improve system capacity and wireless resource utilization.

Another object of the present invention is to propose a method for performing open-loop power control on an S-CCPCH physical channel in a W-CDMA communication system. The present invention proposes to adopt certain power control measures for the S-CCPCH. When the S-CCPCH carries a dedicated type of logical channel belonging to a specific user, the transmission format type of the S-CCPCH is determined frame by frame, and the transmission format is determined according to the determination. Type performs power control on the S-CCPCH frame by frame. In this way, the interference to the system and the occupation of the system caused by the S-CCPCH always sending at full power are avoided. By adopting certain power control measures for the S-CCPCH, the performance of the downlink is effectively improved, and the utilization rate of the wireless resources of the system is further improved. When performing power control on the S-CCPCH, as described above, the S-CCPCH is a public type channel and there is no corresponding dedicated uplink channel. Therefore, the present invention proposes to perform S-CCPCH Power control belongs to the open-loop power control method.

In order to achieve the above object, the present invention proposes a downlink public channel carrying a dedicated type of logical channel according to different logical channel types and required power requirements and characteristics carried in the downlink common channel of a code division multiple access communication system. Channel power control method.

The power control method of the downlink common channel in the code division multiple access communication system of the present invention will be described in detail below with reference to the accompanying drawings, in which:

1 is a schematic diagram of a combination of transmission formats of a code division multiple access transmission channel according to an embodiment of the present invention;

FIG. 2 is a structural block diagram of an SIR tracking loop according to an embodiment of the present invention; FIG. 3 is an implementation block diagram of an S-CCPCH open loop power control method according to an embodiment of the present invention. detailed description

In order to explain the present invention more clearly, the present invention is described by taking a WCDMA communication system as an example, but the present invention is not limited to this. Corresponding downlink common channels having similar structures and functions in other CDMA systems, when carried on them When the logical channel belongs to a dedicated type of a specific user, the method of the present invention may also be used to control the downlink power of the downlink common channel.

Referring to FIG. 1, FIG. 1 illustrates a transmission format combination of a transmission channel of a WCDMA system according to an embodiment of the present invention. As shown in FIG. 1, according to 3GPP specifications 3GPP TS 25.212, 3GPP TS 25.302 and other documents, when multiple transmission channels are multiplexed onto one physical channel, at each transmission time interval (TTI), the upper layer will perform a certain transmission. The Format Combination (TFC) transmits the transport block (TB) of each transmission channel to the physical layer. In order to inform the receiver of the TFC used in the current TTI, the Transmission Format Combination Indicator (TFCI) field of the physical channel gives the current used in the TTI. The index of the TFC. As mentioned earlier, the S-CCPCH is used to carry two types of transmission channels: the forward access channel (FACH) and the paging channel (PCH). Among them, the PCH transmission channel is used to carry the logical channel PCCH. Use BCCH, CCCH, CTCH, DCCH, DTCH and other logical channels. According to the 3GPP specifications 3GPP TS 25.212, 3GPP TS 25.301, 3GPP TS 25.302 and other documents, and referring to the document RP-000447 of the TSG-RAN working group of 3GPP, the TTI of any transmission channel carried on the S-CCPCH can only be taken as a wireless The frame length (10ms), and in each TTI, the PCCH logical channel carried on the PCH transmission channel and various logical channels carried on the FACH transmission channel can be multiplexed onto a radio frame of the S-CCPCH in the following manner: In a 10ms TTI, that is, a radio frame, the PCH and FACH transmission channels can appear individually or simultaneously in a TFC, and the FACH transmission channel may carry one or more logical channels such as BCCH, CCCH, CTCH, DCCH, and DTCH. For example, if a TFC contains a FACE [transmission channel, it may have multiple transmission blocks, and each transmission block may correspond to one of the logical channels such as BCCH, CCCH, CTCH, DCCH, DTCH, etc. That is to say, any one transmission block on the FACH transmission channel may only be one of the logical channels such as BCCH, CCCH, CTCH, DCCH, DTCH, and may not contain two or more logical channel data at the same time.

On the other hand, according to the 3GPP specifications 3GPP TS 25.301, TS 25.331 and other documents describing the functions of each logical channel, the PCCH logical channel carried by the PCH transmission channel and the logical channels carried by the FACH transmission channel and their transmission power have the following characteristics:

(a) The PCCH logical channel carried by the PCH transmission channel and the BCCH and CTCH logical channels carried by the FACH transmission channel do not belong to a specific user. They should be transmitted at full power to cover the entire cell to ensure that all users in the cell can receive it correctly. The information of these channels is the same as other common downlink physical channels, and is generally determined by the network planning process. Therefore, no open-loop is implemented on the PCCH logical channel carried by the PCH transmission channel and the BCCH and CTCH logical channels carried by the FACH transmission channel. Power Control;

(b) According to 3GPP TS 25.331, the CCCH logical channel carried by the FACH transmission channel is mainly used to transmit downlink RRC messages when the DCCH has not been allocated in the CELL-FACH state. This situation often occurs when a UE has just entered the CELL-FACH state and is dedicated at this time. The link has not been established and no downlink DCCH can be used. Therefore, the CCCH logical channel carried by the FACH transmission channel is a relatively rare logical channel, and the CCCH may contain RRC messages that control multiple UEs simultaneously. Therefore, in order to simplify the power control process, the CCCH carried by the FACH transmission channel can be considered The logical channel also covers the entire cell with full power transmission, ensuring that all users in the cell can receive the channel information correctly. Similarly, no open-loop power control is performed on the CCCH logical channel carried by the FACH transmission channel;

(c) The DCCH and DTCH logical channels carried by the FACH transmission channel are targeted at specific users, so they only need to send at the appropriate power so that specific users can receive them correctly, without having to send the same to other logical channels carried by the FACH transmission channel. Send at full power „By performing power control on a specific type of user-specific logical channel carried on the FACH transmission channel carried on the S-CCPCH physical channel, the specific user can receive it correctly, which can avoid or The interference caused by full power transmission to other users is reduced. Therefore, the present invention performs open loop power control on the DCCH and DTCH carried by the FACH.

According to the above analysis, the open-loop power control method of the S-CCPCH proposed by the present invention is as follows:

First, in order to be able to perform slow power control on the DCCH and DTCH carried by FACH, the RNC should establish a corresponding SIR tracking loop for each UE that is in the CELL_FACH state and DCCH / DTCH has been established. The SIR tracking loop and closed loop The external power control loop in power control is similar. When the UE is in the CELL_FACH state, its downlink channel is: physical channel S-CCPCH, transmission channel FACH, logical channel DCCH / DTCH; the uplink channel is: Physical channel PRACH (random access physical channel), transmission channel RACH, logical channel DCCH / DTCHL When the UE receives the DCCH and DTCH on the downlink FACH, it can measure the quality of the channel at the same time. In order to track the SIR currently required by the UE, the UE should report the received quality measurement values of the received DCCH and DTCH on the FACH on the uplink DCCH carried by the RACH to the RC through the RRC measurement report, and the RNC measures the received quality The value is used as the input of the SIR tracking loop to obtain the SIR currently required by the UE. The measurement value of the reception quality of the DCCH and DTCH on the FACH by the UE is preferably a transmission block error rate (BLER). Figure 2 shows a block diagram of a typical SIR tracking loop. In addition, the uplink RRC measurement report of the UE also includes measurement values such as CPICH Ec / o, and is used to calculate the downlink power in an open loop. The measurement values such as CPICH Ec / No are specified by 3GPP TS25.215, which are measurement values that the UE should support.

According to the previous analysis, when the S-CCPCH has the following transmission channel multiplexing modes, no power control is performed:

a) S-CCPCH only carries PCH transmission channels;

b) there is only FACH transmission channel on S-CCPCH, and all FACH only carry one or more logical channels of BCCH, CTCH, CCCH;

c) S-CCPCH carries PCH and FACH, and all FACH only carries one or more logical channels of BCCH, CTCH CCCH;

For other S-CCPCH physical channels that include a dedicated type of logical channel DCCH / DTCH, the downlink transmission power is controlled by each radio frame as follows:

If the TFC of the current radio frame contains only one FACH transmission channel, and the FACH transmission channel carries a DCCH or DTCH logical channel, the downlink transmit power of the frame S-CCPCH can be determined according to the calculation method described below.

If the TFC of the current radio frame includes only the FACH transmission channel, and all logical channels DCCH and DTCH carried by the FACH transmission channel belong to the same UE, then Determine the downlink transmit power of the frame S-CCPCH according to the calculation method to be described below. If the TFC of the current radio frame contains only the FACH transmission channel, and the bearer DCCH and DTCH belong to two or more UEs, the downlink power required by each UE is calculated separately according to the calculation method described below, and the largest one is selected. Value as the downlink transmission power of the frame S-CCPCH. If the FACH contained in the TFC of the current wireless frame not only carries one or more logical channels such as DCCH, DTCH, BCCH, CTCH, CCCH, etc., or also includes a transmission channel carrying PCCH, the frame S-CCPCH need not be calculated And transmit at a preset power, the power makes it cover the entire cell to ensure that all users in the cell can correctly receive the information of the channel.

If the TFC of the current radio frame does not contain the FACH transmission channel carrying the DCCH / DTCH, the frame S-CGPCH is transmitted at a preset power, which power covers the entire cell to ensure that all users in the cell can receive it correctly Information to this channel. In this case, the S-CCPCH transmission power of the frame is not controlled.

When performing S-CCPCH power control according to the above method, in order to optimize the performance of S-CCPCH, the present invention further proposes that the RNC may preferably perform S-CCPCH packet scheduling control according to the following principles:

□ Avoid situations in which the FACH carries not only DCCH, DTCH, but also one or more logical channels such as BCCH, CTCH, CCCH, etc., or the transmission channel carrying PCCH in the TFC of the S-CCPCH radio frame;

□ In this case, that is, the TFC of the S-CCPCH wireless radio only contains the FACH transmission channel, and the DCCH and DTCH carried by the S-CCPCH radio belong to two or more UEs, the RNC should try to use as much as possible in packet scheduling. The downlink transmission power of the UE is arranged as close as possible to the DTCH / CCH of the UE.

When the fan needs to calculate the downlink transmission power of the S-CCPCH, the existing method may be adopted. For example, the literature "Radio network planning and Optimization for UMTS" can be adopted, (J. Laiho, A. Wacker, T. Novosad, etc., Published by John Wiley & Sons, 2002):

Each parameter in the above formula represents the following quantities:

ρχ downlink transmit power at the current moment;

a downlink orthogonality factor (0≤ «≤1) related to a specific UE,« = 1 means completely orthogonal;

W chip rate;

R bit rate of the data portion of the physical channel;

The total maximum downlink transmit power of the P _max base station;

λ The ratio of the transmit power of the downlink common pilot channel CPICH to P _max ;

V _DL downlink load factor (0 ~: 100%), the ratio of the current total transmit power of the base station to the total maximum transmit power;

m _H is CPICH Ec / No, which is the ratio of the energy of each chip of the received CPICH to the total power of the received band;

^SIR ',' The received signal-to-interference ratio currently required for this physical channel.

Among them, (/ w.) _OTffl is the current measurement result reported by the UE, is the current measurement result reported by the base station, ^. 'Is the current SIR target output by the previous fan SIR tracking loop. In addition, if the orthogonality of the downlink is not considered, Equation (1) can be further simplified.

In addition, for the slow open-loop power control of S-CCPCH, the present invention also proposes that the S-CGPCH downlink transmit power at the current moment for a specific UE can be further calculated according to the following formula:

P (k) = -P (k -l) + (\-fi) P k) (2)

Where the factor is 0 ~ 1, the closer the value is to 0, then the power value before ¾ It plays a smaller role, and the current power is mainly determined by the power value calculated in the open loop. On the contrary, the closer the value is to 1, the larger the role of the previous power value ", and the current power is less affected by the power value calculated by the open loop. For the UE, at the current time k according to formula (1) The calculated value, (is the S-CCPCH downlink transmit power at the current time corresponding to the UE smoothed by formula (2). Compared with the downlink transmit power calculated directly by formula (1), using formula (2) can smooth out the direct The instability caused by measurement parameter errors in the calculation can better adapt to changes in the channel environment due to UE movement.

Figure 3 shows a block diagram of the S-CCPCH slow open-loop power control implementation according to the present invention. In this figure, the protocol data units of logical channels such as BCCH, PCCH, CCCH, CTCH, DCCH, DTCH, etc. are first mapped into transmission blocks of the transmission channel FACH / PCH according to specifications such as 3GPP TS25.321. Thereafter, these FACH / PCH transport blocks will enter the FACH / PCH packet scheduling unit. This unit determines the priority of each FACH / PCH transport block and determines each radio frame of each S-CCPCH (for S_CCPCH (TTI) is the TFC, and outputs the connection frame number (CFN), the FACH / PCH transmission block of the corresponding frame, and the corresponding transmission format indication (TFI) to the data frame protocol processing unit of FACH and PCH.

On the other hand, according to the results of FACH / PCH packet scheduling, the S-CCPCH multiplexed with the FACH transport channel carrying DTCH / DCCH is first distinguished, and the S-CCPCH that does not reuse the FACH carrying DTCH / DCCH is The frames are power controlled and transmitted at a predetermined full power to cover the entire cell. For the S-CCPCH multiplexed with the FACH carrying DTCH / DCCH, the used TFC will be judged on a frame-by-frame basis, and the downlink transmit power of the current frame will be determined based on the TFC of the described S-CCPCH.

In FIG. 3, five cases are shown, where case (1) is that the TFC of the current radio frame contains only one FACH transmission channel, and the FACH transmission channel carries a DCCH or DTCH logical channel; case (2) is the current wireless The TFC of the frame contains only the FACH transmission channel, and all the logical channels carried by the FACH transmission channel Both DCCH and DTCH belong to the same UE; case (3) is that the TFC of the current radio frame contains only FACE [transmission channel, and the bearer DCCH and DTCH belong to two or more UEs; case (4) is the TFC of the current radio frame The FACH contained in it not only carries one or more logical channels such as DCCH, DTCH, BCCH, CTCH, CCCH, etc., or also includes a transmission channel carrying PCCH; Case (5) is that the TFC of the current radio frame does not include the carrying DCCH / FACH transmission channel of DTCH.

In FIG. 3, when calculating downlink power according to formulas (1) and (2), the current SIR target value provided by the SIR tracking ring of the corresponding UE and the related measurement results reported by the current UE and Node B will be used. The FACH power level value of each frame of each S-CCPCH is also sent to the data frame protocol processing unit of FACH and PCH at the same time. Among them, the FACH data frame protocol processing unit will use the connection frame number (CFN) output by the FACH packet scheduling unit, the FACH / PCH transmission block of the corresponding frame, and the corresponding transmission format indication (ΊΤΙ), as well as those obtained by open-loop power control. The transmission power level value of the corresponding frame forms a FACH data frame; and the PCH data frame protocol processing unit will use the connection frame number (CF) output by the FACH packet scheduling unit, the corresponding FACH / PCH transmission block, and the corresponding transmission Format indication (TFI), etc., to form a PCH data frame.

FACH and PCH data frames are transmitted to Node B through the interface lub between Node B and RNC. Finally, Node B completes the S-CCPCH multiplexing of FACH PCH and the mapping of physical channels. For detailed description of FACH PCH data frame protocol, please refer to 3GPP TS25.434, TS25.435 and other protocols).

It should be noted that, although the embodiments of the present invention provide five scenarios for determining the downlink transmit power of the current S-CCPCH frame, the present invention is mainly when the S-CGPCH only carries a dedicated type of logical channel DTCH / During CCH, power control is performed on the S-CCPCH radio frame, and the transmission power of the S-CCPCH radio frame in such a case is adjusted to reduce interference to other users and improve radio resource utilization. When the S-CCPCH does not carry the above-mentioned dedicated type of logical channels or in addition to other dedicated logical channels, the S-CCPCH is The radio frame does not perform power control and is transmitted at a predetermined power in a manner well known to those skilled in the art.

In addition, it should also be pointed out that although the present invention is described by taking the S-CCPCH channel of WCDMA as an example in the embodiment, the method involved in the present invention is not limited to this. The S-CCPCH is similar to the power control of the common downlink channel, and the principle of the method proposed by the present invention is also applicable. For example, those skilled in the art can easily know that in the CDAM2000 system, the forward common control channel (F-CCCH) can also use the method of the present invention to perform power control.

Claims

1. An open loop power control method for a downlink common channel in a code division multiple access system, characterized in that the method includes the following steps:

a) distinguishing downlink common channels multiplexed with dedicated type logical channels;

b) judging, on a frame-by-frame basis, the downlink common channel carrying a dedicated type of logical channel, the transmission format combination of the downlink common channel;

c) According to the current transmission format combination type of the radio frame, the transmission power of the downlink common channel radio frame carrying only the dedicated type logical channel is controlled on a frame-by-frame basis.

2. The method according to claim 1, wherein the code division multiple access system is a WCDMA system, the downlink common channel is an S-CCPCH physical channel, and the dedicated type logical channel is DCCH and / or DTCH logical channel.

3. The method according to claim 2, wherein the frame-by-frame control of the transmission power of a downlink common channel radio frame that only carries a dedicated type of logical channel comprises: if the transmission format combination of the current radio frame is only Including the FACH transmission channel and carrying DCCH or DTCH, the current SIR target value of the corresponding UE generated by the SIR tracking loop and the current measurement result of the corresponding UE are used to calculate the downlink transmit power of the frame S-CCPCH.

4. The method according to claim 3, characterized in that if all the DCCH and DTCH carried on the FACH transmission channel belong to the same UE, the current SIR target value of the corresponding UE generated by the SIR tracking loop is used, and the corresponding The current measurement result of the UE calculates the downlink transmit power of the S-CCPCH in the frame.

5. The method according to claim 3, wherein if the DCCH and DTCH carried on the FACH transmission channel belong to two or more UEs, the current SIR target value of the corresponding UE generated by the SIR tracking loop is used. And the current measurement result of the corresponding UE, directly calculate the downlink power required by each UE separately, and select the maximum value as the downlink transmit power of the frame S-CCPCH.

6. The method according to claim 3, 4 or 5, wherein the SIR tracking loop is a corresponding SIR tracking loop established by the RNC for each UE that is in the CELL-FACH state and has established a dedicated link. Road, where:

The UE reports the reception quality measurement values of the DCCH and DTCH on the received FACH to the RNC through the RRC measurement report;

The RNC then uses the received quality measurement value as the input of the SIR tracking loop to calculate the SIR target value currently required by the UE.

7. The method according to claim 6, wherein the measured value of the received quality is a transmission block error rate, and the reported uplink RRC measurement report of the UE further includes a CPICH Ec No measurement value.

8. The method according to claim 3, wherein the downlink transmission power ^{p (fe)} of the common channel at the current moment of the UE can be further calculated by the following formula:

Where is a factor of 0 ~ 1, which is the power value directly calculated by the UE at the current time k, using the current SIR target value of the corresponding UE generated by the SIR tracking loop, and the current measurement result of the corresponding UE.

9. The method according to claim 2 or 3, further comprising the step of performing packet scheduling on the S-CCPCH physical channel.

10. The method according to claim 9, characterized in that the step of scheduling the S-CCPCH physical channel comprises preventing the transmission format of the S-CCPCH radio frame from simultaneously carrying DCCH, DTCH and BCCH, CTCH. One or more logical channels of the CCCH, or include a PCCH transmission channel.

11. The method according to claim 9, characterized in that, if the combination of transmission formats of the current radio frame includes only FACH transmission channels, and the bearer DCCH and DTCH belong to two or more UEs, the RNC DTCH / DCCH of UEs with similar required downlink transmission power are arranged together in packet scheduling.