WO2005011143A1

WO2005011143A1 - A power control method and apparatus for time division duplex code division multiple access system

Info

Publication number: WO2005011143A1
Application number: PCT/CN2004/000867
Authority: WO
Inventors: Bin Zhou; Hai Bi; Desuo Zhou; Hua Yang
Original assignee: Da Tang Mobile Communications Equipment Co., Ltd.
Priority date: 2003-07-25
Filing date: 2004-07-26
Publication date: 2005-02-03
Also published as: CN1479541A; CN1230016C

Abstract

The present invention discloses a power control method for time division duplex code division multiple access system, comprising: calculating the estimate value of the current transmission power based on the information acquired from the current reception signal; calculating the absolute value of the difference between the estimate value of the current transmission power adjusting step size; adjusting the signal transmission power according to the determined step size. At the same time the present invention provides a power control apparatus for time division duplex code division multiple access system, comprising : the signal transceiver unit, the power measure unit, the control and calculation unit, the storage unit and the power adjusting unit. According to the scheme of the present invention, it is enabled to reduce the burden of the air interface, simultaneously to ensure the dynamic adjusting of the power control step size to be performed in time and properly.-

Description

Method and device for power control of time division duplex code division multiple access system

Technical field

The present invention relates to code division multiple access mobile communication technology, and in particular, to a method and device for power control of a time division Chinese division code division multiple access (TDD CDMA) system. Background of the invention

In code division multiple access (CDMA) systems, the purpose of power control is mainly to overcome near-far effects, reduce system interference, and save power. This technology is to evaluate the received signal energy or signal-to-interference (SIR) index at the receiver. On the basis of this, the fading in the wireless channel is compensated in a timely and appropriate manner, thereby maintaining the communication quality of the user without causing unnecessary interference to other users in the same wireless resource, and ensuring system capacity.

In the existing CDMA system, power control is divided into forward power control and reverse power control, and the process is mainly divided into outer loop power control, inner loop power control and open loop power control. Reverse power control, also known as uplink power control, is designed to control the transmit power of the terminal. Reverse power control can make each terminal's transmit power remain the most reasonable to save energy and extend the battery life of the terminal. Forward power control, also known as downlink power control, generally involves the user terminal controlling the transmission power of the base station (Node B) according to the measurement result of the signal-to-interference ratio.

The above line power control method is taken as an example, and its control process is described as follows.

In the traditional uplink power control method, the base station assists the user terminal to adjust the transmit power of the user terminal, so that the terminal always maintains a reasonable transmit power. Specifically: The base station detects the SIR of the demodulated uplink traffic channel at a certain interval, and then compares it with the SIR target value (SIR target). If the measured value is higher than the target value, it sends a Command; otherwise, send a command to increase transmit power. Terminal received After the power control command, the transmission power is adjusted according to a predetermined step size. The target value of the SIR of the traffic channel is adjusted according to the quality of the communication link through an outer loop power control process.

However, in the above-mentioned power control process, how to determine the step size of the power adjustment is a difficult problem. In practical applications, such as: In current CDMA systems, a fixed step power control method is basically used. In this way, if the step size is too small, the effect of power control is not enough to overcome the rapid changes in the environment, for example: In the case of deep slow fading, the path loss can even change above 20 ~ 30dB; and if the step size is too large, In the case that the system does not need to change much power, the effect of instability will occur, which will increase the interference in the system and affect the capacity of the CDMA system. In addition, during a communication connection, the user's environment is also dynamically changing. Using a fixed step size does not guarantee that the power control effect is the best during the entire communication process.

In order to solve the above problems, some power control algorithms with multiple steps have been proposed. Generally, the SIR value and the SIR target value of the received signal are compared at the base station side, and the difference between them is obtained and determined by the size of the difference. Step size of uplink inner loop power control. This type of algorithm usually uses the following methods: Definition: ¾arg | If 0 <γ <δ then the step sizes Step _ne , ', such as Δ1 = ldB;

If the step size Step _ne , such as Δ2 = 2dB;

If δ ₂ <γ <δ then the step size is Δ3 ■ = 3dB „

However, if such a solution is adopted, the decision-making side that triggers the step size adjustment and the execution side that adjusts the transmission power are in two entities, a terminal and a base station, respectively. The base station not only needs to send a power control command, but also sends a power control step size adjustment It is indicated that this will increase the burden on the air interface and its reliability is affected by the channel environment. Summary of the invention

In view of this, a main object of the present invention is to provide a power control method for a time division duplex code division multiple access system, which can ensure that the power control step size can be adjusted dynamically and timely in a timely manner while reducing the burden on the air interface.

Another main object of the present invention is to provide a device for power control in a time division duplex code division multiple access system. By setting the device in a terminal or a base station, dynamic adjustment of a power control step size can be realized and the burden on an air interface can be reduced.

According to the first object of the present invention, a method for power control of a time division duplex code division multiple access system provided by the present invention includes:

a) Calculate the current transmission power estimate value based on the information obtained from the current received signal; b) Calculate the absolute value of the difference between the current transmission power estimate value and the currently used transmission power value obtained in step a);

c) determining the required power adjustment step size according to the result obtained in step b);

d) adjusting the signal transmission power according to the step size determined in step c).

The information obtained from the currently received signal in this method includes: the interference power value of the current traffic channel and the path loss value of the received signal.

Step a) of the method includes:

Calculate the open-loop estimated transmission power of the traffic channel based on the information obtained from the currently received signal;

Take out the last estimated transmission power;

A predetermined smoothing factor is used to calculate the current uplink transmission power weighted smoothed transmission power estimation value according to the obtained open loop estimated transmission power and the last transmission power estimation value.

In step a) of the method, the estimated transmission power value ^ρ τχ satisfies the formula "P + (1—) Ργχ last · Among them, "^-'." Is the last transmission power estimation value, "is a smoothing factor, and the open-loop estimated transmission power of the traffic channel,

And P satisfies the formula P

Where ^p ′ is a path loss value of the received signal,

PRX is the desired received power on this channel,

pppCHdes

And ^KA PDPCHdes satisfies the formula I PDPCH;

Among them, (5 ^). ^ / Is the received signal-to-interference ratio expected on the traffic channel,

H is the interference power value on the current traffic channel.

The interference power value of the traffic channel in this method is obtained by the following steps: For uplink power control, the interference power value of the uplink traffic channel is measured by the base station and broadcasted to the cell through system messages; for downlink power control, the downlink traffic channel's The interference power is measured by the terminal and reported to the base station periodically.

In the method, the power control is uplink power control on the terminal side in the CDMA system, and the interference power value of the service channel is the uplink time slot interference signal code rate, and is obtained by the following steps: The base station periodically measures the uplink time slot interference. For the signal code rate, the measurement result is broadcast to the cell through a system message. After receiving the system message, the terminal uses the interference signal code rate carried in the message as the interference power value of the current service channel.

Step c) of the method includes the following steps:

Setting a first predetermined threshold value and a second predetermined threshold value, and the greater than; comparing the magnitude relationship between the result obtained in step b) and the first predetermined threshold value and the second predetermined threshold value, if step b) If the result obtained is greater than the first predetermined threshold value, the power adjustment step size is increased by one step level; if the result obtained in step b) is less than the second predetermined threshold value, the power adjustment step size is decreased by one step level; if step b) The results are in The step size does not change between a predetermined threshold and a second predetermined threshold.

The method further includes:

Setting a first predetermined threshold value and a second predetermined threshold value ^δ ι, and said greater than; setting a third predetermined threshold value;

Step c) further includes: obtaining a path loss PL of the received signal. _SS ; Calculate the average value of the path loss estimates for the most recent scheduled times;

Calculate the path loss value PL of the received signal. The absolute value of the difference between _ss and the average value of the most recent predetermined path loss estimation value ^y = I ^PLOSS_JPM I; the step C) is: comparing the absolute value ^^^^-^ with a third predetermined threshold value ^ The relationship between the results, and the relationship between the result obtained in step b) and the first predetermined threshold value and the second predetermined threshold value, if the result obtained in step b) is greater than the first predetermined threshold value, or greater than the third predetermined threshold value A threshold value, the power adjustment step is increased by a step level;

If the result obtained in step b) is less than the second predetermined threshold value and is not greater than the third predetermined threshold value 4, the power adjustment step is reduced by one step level.

If the result obtained in step b) is between the first predetermined threshold value and the second predetermined threshold value and is not greater than the third predetermined threshold value, the step size is unchanged.

The method further includes:

Set more than one interval for the absolute value of the difference obtained in step b), each interval corresponding to a reference step size;

Set more than one interval for the absolute value of the difference between the path loss P _SS of the received signal and the average value of the most recent predetermined path loss estimate ^γ = I ^Ploss ", each interval corresponding to a parameter Test step

Step C) further includes:

Get the path loss PL of the received signal. _SS ;

Calculate the average of the most recent predetermined path loss estimates;

Calculate the absolute value of the difference between the path loss P _{SS of the} received signal and the average value of the most recent predetermined path loss estimation value =. ^SS — |; obtain the reference step corresponding to the interval to which the current value of I ^PLOSS_JPM I belongs;

Obtaining a reference step size corresponding to the interval to which the result obtained in step b) belongs;

A larger one is selected as the power adjustment step size from the obtained reference step sizes. In this method, the path loss PL of the received signal is obtained. _ss is the power fading value on the beacon channel obtained by measuring the received beacon channel signal.

In this method, the beacon channel is a downlink pilot time slot or a main common control physical channel. Step d) of the method includes: extracting a transmission power control command from a currently received signal, and if the transmission power control command instructs to increase the terminal transmission power, then increasing the transmission power according to the step determined in step c); if the transmission power control The command indicates that the terminal transmit power is reduced, and then the transmit power is reduced according to the step size determined in step c).

Step d) of the method includes: comparing the magnitude relationship between the current transmission power estimated value obtained in step a) and the currently used transmission power value. If the current transmission power estimated value is greater than the currently used transmission power value, then follow step c) The determined step size increases the transmission power; if the current transmission power estimated value is less than the currently used transmission power value, the transmission power is reduced according to the step size determined in step c).

According to another object of the present invention, a device for power control of a time division duplex code division multiple access system provided by the present invention is characterized in that it includes:

A signal transceiver unit, configured to receive a signal transmitted by the other party to obtain a signal parameter, and And transmitting signals to each other;

A power measurement unit, configured to obtain a currently used transmission power;

A control and calculation unit, configured to obtain a current transmission power estimate value according to a signal received by the signal transceiver unit, and obtain a currently used transmission power through the power measurement unit; and calculate the current transmission power and the current transmission power estimation value. Absolute value of the difference;

The storage unit is configured to store a currently used transmission power value and a previous transmission power value; a power adjustment unit is configured to adjust a transmission power according to a calculation result of the control and calculation unit. The device further includes:

The control and calculation unit further includes a loss deviation calculation module for calculating an average value of the path loss estimates of the latest predetermined times and an absolute value of a difference between the path loss of the received signal and the average value of the path loss estimates of the most recent predetermined times. Value

The storage module also stores previously estimated path losses.

As can be seen from the above, the present invention provides a method and device for power control of a time division duplex code division multiple access system. The estimated transmission power obtained by the open-loop power control method is the same as the actual transmission power at the current moment. Compare and use this difference as the basis for adjusting the step size of the closed-loop power control. While the step size of the power adjustment can be dynamically changed according to the environment, the adjustment of the step size of the power control is implemented as far as possible within the step size adjuster, thereby avoiding the air interface required for the adjustment at the network side. The signaling overhead is highly implementable. In addition, the present invention further directly uses the estimated value of the path loss as a basis for adjusting the power control step size, thereby improving the accuracy and reliability of the power adjustment. Brief description of the drawings

FIG. 1 is a flowchart of a power control method combining an open loop and a closed loop according to a first preferred embodiment of the present invention;

FIG. 2 is a power control method combining open loop and closed loop according to a second preferred embodiment of the present invention. Flow chart of the law;

3 is a flowchart of a power control method in which an open loop and a closed loop are combined according to a third preferred embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a power control device for a time division duplex code division multiple access system according to the present invention. Mode of Carrying Out the Invention

The present invention will be described in further detail below with reference to the drawings and specific embodiments.

In a time-division duplex CDMA system, because the uplink and downlink use the same frequency to transmit signals, they are used only in time-sharing. At the same time, the time interval between the uplink and downlink can be ensured by the frame structure design to be small enough to ensure that During the interval between trips, the user terminal can still think that its wireless environment does not change even when it is moving at high speed. In this way, it can be basically considered that the uplink and downlink transmission characteristics of the TDD mobile communication system are consistent.

Based on the above considerations, the above row power control is taken as an example. The idea of the present invention is to use an open-loop power control method to estimate the transmit power that a user terminal should use, and compare it with the actual transmit power at the current moment, and use this difference as a closed loop. Basis for power control step size adjustment. In this way, the network only needs to broadcast the uplink slot interference measurement value to the cell periodically. When the terminal performs the uplink power control step size adjustment, the adjustment of the power control step size is completely implemented in the user terminal, thereby avoiding The signaling overhead on the air interface required by the network side for adjustment is highly implementable. At the same time, the present invention directly uses the estimated value of the path loss as a basis for adjusting the power control step size, and the terminal can also send the currently used step size value to the base station end through uplink signaling.

Further analysis, usually in a CDMA system, a closed-loop power control process is necessary, which can enable a terminal or a base station to meet relevant channel quality requirements with as little power as possible. Closed-loop power control can pass the interaction process between the base station and the terminal with a certain adjustment step size. Reach the balance of the signal-to-interference ratio. In the design of the existing CDMA system, a beacon channel generally exists in the downlink direction, and the transmit power of the beacon channel is broadcast to the entire cell range through a system message, which can be used as a reference for user terminals when implementing uplink open-loop power control. In the Time Division Synchronous Code Division Multiple Access (TD-SCDMA) system that has been standardized in the Third Generation Mobile Communications Standards Organization (3GPP), a special time slot, such as the downlink pilot (DwPTS), or the main common control physical channel ( PCCPCH) for beacon channel purposes. Because the same frequency is used for the uplink and downlink of the TDD system, the open-loop power control of the system can be done very accurately for a single user terminal. However, directly applying the open-loop power control often results in an excessively large adjustment of the transmit power, which makes the The stability of the entire system is reduced. Therefore, in the uplink or downlink power control, the principle of open loop power control can be used, and the signal of the beacon channel whose transmission power is known and the interference information of the current traffic channel are used to estimate the uplink or downlink signal should have Transmit power, and adaptively adjust the step size of the closed-loop power control according to this information to perform stable and accurate transmit power adjustment, so as to achieve an optimized power control effect.

The uplink power control process in a CDMA system is taken as an example to describe a preferred embodiment of the present invention. When performing uplink power control in the present invention, the step size of the terminal power adjustment is divided into at least two or more levels, for example: the step size is divided into five levels, which are 0.5dB, 0.8dB, ldB, 1.2dB, 1.5dB. The information obtained by measuring the downlink signal is used to trigger the adjustment of the step size of the closed-loop power control, and the decision of the step size adjustment and the execution of the transmission power adjustment are all completed at the terminal.

Referring to FIG. 1, FIG. 1 is a flowchart of a power control method combining an open loop and a closed loop according to a first preferred embodiment of the present invention.

Step 120: The terminal 100 calculates an estimated transmission power P _{τχ of the} current uplink transmission power weighted smoothing according to the related parameters obtained from the current received signal.

In this step, the process of obtaining related parameters from the currently received signal includes: receiving a service signal transmitted by the base station 105 through the downlink wireless channel 110, and obtaining the downlink from the The perturbation power on the wireless channel 110. The signal of the beacon channel is received through the beacon channel, and the signal fading value on the beacon channel is obtained by measuring the signal. The signal fading value can be used as the path loss of the received signal.

The specific calculation of _ρτχ refers to formula (1):

^P TX = ^aP DPCH + 0- ^{a P} TXJast (\) In formula (1), ^ is the transmission power estimated value after weighting and smoothing the current uplink transmission power; ρτχ ″ _{α the} last estimated transmission power ^{P of the} terminal 100 ^ value;

"Is a smoothing factor;

^P OPCH represents the open-loop estimated transmit power of the service channel, which can be calculated with reference to formula (2):

^ DPC-PDPCHdes + ^ Loss (2) In formula (2), in order to receive the path loss of the signal, in the TD-SCDMA mobile communication system, a special time slot of downlink pilot or the main common control physical channel is specifically used For the purpose of the beacon channel, the measured signal fading value on the beacon channel is used here. Value

Represents the desired received power on this channel _{1 10} , you can refer to the formula

(3) Calculation:

PDPCHdes

W ^IK ) DPCH One "

^{In J} PDPCH (3) Formula (3), (^^^ / indicates a desired received signal-to-interference ratio on the channel no; / wc "indicates interference power on the downlink wireless channel 110, and in this embodiment ⁷ ^^ The value of c / is equal to the value of the interference signal code rate (ISCP) of the uplink time slot. The specific acquisition method may be that the base station 105 periodically measures the uplink time slot ISCP, and periodically transmits the measurement result through the system message. Broadcast to the cell; connected The terminal 100 in the mode should monitor the system broadcast message at the same time, and after receiving the ISCP parameter of the uplink time slot, update the corresponding internal saved value.

Step 125: Calculate the absolute value of the difference between the transmission power P _present currently being used by the terminal 100 and the estimated transmission power after weighted smoothing of the current uplink transmission power.

Step 130,135, calculated in step 125 the obtained ^{Δ = Ι} _ ^p ^ ^es a first predetermined threshold value and ^ 'and compares a second predetermined threshold value, it is determined in the range, and the corresponding step according to the determination result Long adjustment.

Wherein, the power difference threshold value In the following embodiments of the present invention, the range of the first predetermined threshold value is selected from 1 to 1.5 dB, and the range of the second predetermined threshold value is selected from 0.2 to 0.5 dB. The above specific judgment principles are as follows:

If the current Δ value is greater than the first predetermined threshold, it indicates that the current transmission power is significantly different from the required transmission power estimated by the open-loop power control, and then the power adjustment step of the terminal is increased by a step level in step 135;

If the current Δ value is less than the second predetermined threshold value, it means that the difference between the current transmission power and the required transmission power estimated by the open-loop power control is small, then the step of adjusting the power adjustment step of the terminal is reduced by a step level in step 135

If the current Δ value is between the first predetermined threshold value A and the second predetermined threshold value, it indicates that the difference between the current transmission power and the required transmission power estimated by the open-loop power control is suitable for the power adjustment step size of the terminal, then in step 135 Do not adjust the step size.

When the step size before the adjustment has reached the maximum, that is, when the maximum step size has reached 1.5 dB, if the condition for increasing the step size is still satisfied after the above determination process, the maximum step size is still maintained at this time; similarly, when the When the step size has reached the minimum case, if the condition for reducing the step size is still satisfied after the above determination process, the minimum step size is still maintained at this time. In practical applications, the conditions A and S of the two triggering step adjustments can be judged in order according to their numbering order, that is, the comparison result of the currently obtained Δ value and the comparison of the currently obtained Δ value and result. Of course, the reverse order can also be used.

Step 140: The terminal 100 extracts a transmit power control (TPC, Transmit power control) command from a signal transmitted by the base station, and determines whether the terminal transmit power needs to be increased or the terminal transmit power is reduced according to the command.

The specific process of this step may be performed according to the current standard, that is, according to the current standard of the CDMA system, the base station estimates the received terminal signal-to-interference ratio at a frequency of up to 200 Hz and compares it with the target SIR. When the SIR measured by the base station is greater than the target SIR, a TPC = 0 command is sent to the terminal in the next 5ms subframe to instruct the terminal to reduce the transmit power; when the measured SIR is less than the target SIR, the next SIR is A command of TPC = 1 is sent to the terminal within a 5ms subframe, instructing the terminal to increase the transmission power. After receiving and extracting the TPC command, the terminal determines whether the TPC value is 0 or 1; if it is 0, then it is determined that the transmission power of the terminal needs to be reduced; if it is 1, it is determined that the transmission power of the terminal needs to be increased.

Step 145: The terminal adjusts the transmission power of the terminal according to the step size determined in step 135 and the instruction obtained in step 140, and transmits a signal according to the adjusted transmission power, so that the signal is transmitted to the base station (Node) through the uplink wireless channel 115. B) 105.

When using this scheme for simulation, compared with the fixed step size algorithm (with a step size of 1 dB) under the same service intensity, the call drop rate (1%) can be reduced. The call drop criterion used here is: If the SIR value of the received signal is continuously lower than the target SIR value for 140ms, then the terminal is judged to drop the call.

Referring to FIG. 2, FIG. 2 shows a flowchart of a power control method in which an open loop and a closed loop are combined in a second preferred embodiment of the present invention, where an auxiliary step adjustment step 205 is added. For brevity of description, the same parts as in FIG. 1 will not be described here in detail, and the description will be focused here. Different from Fig.1.

In step 120, the terminal 100 calculates the transmission power estimated value P _{τχ of the} current uplink transmission power weighted smoothing according to the related parameters obtained from the current received signal.

Step 125: Calculate the absolute value of the difference between the currently used transmission power P _{present of the} terminal 100 and the estimated transmission power after weighted smoothing of the current uplink transmission power, ^Δ =-

. In step 130, the value of ^{Δ =} ^-^^^ 1 calculated in step 125 is compared with the first predetermined threshold value and the second predetermined threshold value to determine its range.

The auxiliary step adjustment step 205 includes:

Step 210: Obtain an average value of the path loss estimation values of the last two or more times ^:

In formula (4), 'is the path loss measurement value of the previous i times, M is the number of times taken to calculate ^, and in this embodiment, M = 2 is taken, that is, the average value of the path loss estimation values of the previous two times is taken.

Step 220: Calculate the signal fading on the beacon channel (that is, the path loss of the received signal)

The absolute value of the difference between P _Loss and the average of the path loss estimates is ^γ = I ^PLOSS "^.

Step 225, judge

Whether it is greater than the third predetermined threshold, and according to the judgment result, it proceeds to step 135 for step size adjustment.

Wherein, the third predetermined threshold value ranges from 0.5 to 1 dB in this embodiment.

Step 135: Adjust the step size according to the judgment results of steps 130 and 225. The specific step adjustment principles are:

If the current transmission power is greater than the first predetermined threshold value, it indicates that the current transmission power is significantly different from the required transmission power estimated by the open-loop power control; or if the current transmission power is greater than the third predetermined threshold value, which indicates that the channel environment is greatly changed, in step 135 Increase the power adjustment step of the terminal A stride level

If the current Δ is less than the second predetermined threshold value, it means that the difference between the current transmission power and the required transmission power estimated by the open-loop power control is small; and at the same time, it is not larger than the third predetermined threshold value ^{δ, which} indicates that the channel environment has not changed significantly. In step 135, the power adjustment step of the terminal is reduced by a step level.

If the current Δ is between the first predetermined threshold value and the second predetermined threshold value ^, it means that the difference between the current transmission power and the required transmission power estimated by the open-loop power control is suitable for the power adjustment step of the terminal; The third predetermined threshold value indicates that the channel environment has not changed greatly, and the step size is not adjusted in step 135.

Wherein, the above-mentioned auxiliary step adjustment process 205 may be performed in parallel with the steps 120-130 at the same time, or may be performed in any order.

Step 140: The terminal 100 extracts a TPC command from a signal transmitted by the base station, and determines whether the terminal transmission power needs to be increased or the terminal transmission power is reduced according to the command.

Step 145: The terminal adjusts the transmission power of the terminal according to the step determined in step 135 and the instruction obtained in step 140, and transmits a signal according to the adjusted transmission power, so that the signal is transmitted to the base station through the uplink wireless channel 115. Node B) 105.

Referring to FIG. 3, FIG. 3 shows a flowchart of a power control method in which an open loop and a closed loop are combined in a third preferred embodiment of the present invention, where a hierarchical processing of measurement parameters is added. For brevity of description, the same parts as those in FIGS. 1 and 2 are not described here in detail, and parts different from those in FIGS. 1 and 2 are mainly described here.

In this embodiment, the parameter Δ is classified. Divide Δ into multiple intervals, and there is a —correspondence relationship between each interval and the step level. In this embodiment, there are 3 intervals, which are: interval ^σ ι = „ ^Β , interval ^σ 2 = [2dB, 6dB), interval σ ₃ = [6dB, ∞), and the reference step sizes corresponding to each interval are: 0.5dB, ldB, 1.5dB. Divide ^ into multiple Intervals, and there is a —correspondence relationship between each interval and step level, in this embodiment:

The three intervals are: = [° ^dB ' ^2dB ); «2 = [2dB, 6dB). A ₃ = [6dB, ∞), the reference step sizes corresponding to the intervals are: 0.5dB, ldB, 1.5dB.

In step 315, compared with step 130 in the above two embodiments, it is modified to determine which interval ^σ "the current Δ value belongs to, and select the power adjustment step size ΔPl corresponding to the interval.

In step 310, compared with step 225 in the second embodiment, it is modified to determine which interval "" the current value ^ belongs to, and select the power adjustment step size ΔP2 corresponding to the interval.

In step 320, compared with step 135 in the above two embodiments, it is modified to select the maximum value of ΔP1 and ΔP2, that is, AP = max (AP1, ΔP2) as the step size of the actual power adjustment.

When using this scheme for simulation, compared with the fixed step size algorithm (step size using IdB) under the same service intensity, the call drop rate can be reduced (1%). The call drop criterion used here is: If the SIR value of the received signal is continuously lower than the target SIR value for 140ms, then the terminal is judged to drop the call.

Although in the three embodiments described above, TPC commands are used for power control, in fact, the present invention can also perform power control without TPC commands. For example: Compare the current uplink transmit power weighted smoothed transmit power estimate value ^P ^ with the current transmit power value P _present . If ^ "^ Pp ^, then it can be determined that the terminal transmit power should be increased; if ^pτχ <P _present , It is determined that the transmission power of the terminal needs to be reduced.

If the method of the present invention is used to implement the step adjustment of the downlink power control at the base station side, the terminal needs to periodically report the path loss value measured on the downlink pilot signal and the interference information in the downlink signal service channel.

Referring to FIG. 4, a device for power control of a time division duplex code division multiple access system according to the present invention, include:

The signal transceiver unit is configured to receive a signal transmitted by the other party to obtain a parameter of the signal, send it to the control and calculation unit, and transmit the signal to the other party;

A power measurement unit, configured to obtain the currently used transmission power P _present and send the measurement result to the control and calculation unit;

A control and calculation unit, configured to obtain the weighted and smoothed transmission power estimated value of the current uplink transmission power according to the signal parameters received from the signal transceiver unit, and obtain the currently used transmission power P _present through the power measurement unit; and calculate the current used The absolute value of the difference between the transmit power of the

-And send the calculation result to the power adjustment unit;

A storage unit, configured to store a currently used transmission power value p _present and a previous transmission power value;

The power adjusting unit is configured to adjust the transmission power according to the calculation result of the control and calculation unit. In addition, the control and calculation unit may further include a loss deviation calculation module, configured to calculate an average value of the most recent predetermined path loss estimation value, and calculate an average of the path loss of the received signal and the most recent predetermined path loss estimation value. Absolute value difference

7-Loss-Dead M | · The storage module also stores previously estimated path losses.

The method and device provided by the present invention can be applied to a time division duplex code division multiple access system including: CDMA, TD-SCDMA, Wideband Code Division Multiple Access (WCDMA), CDMA2000, and the like.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the present invention. Within the scope of protection.

Claims

Claim

1. A method for power control of a time division duplex code division multiple access system, comprising:

2. The method according to claim 1, wherein the information obtained from the currently received signal comprises: the interference power value of the current traffic channel and the path loss value of the received signal.

3. The method according to claim 2, characterized in that step a) comprises: calculating an open-loop estimated transmission power of a service channel based on information obtained from a currently received signal;

Take out the last estimated transmission power;

4. The method according to claim 3, wherein, in step a), the estimated transmission power value ^ρ τχ satisfies a formula ^P = ^aP D''cH + G-c) P _TXJast ; wherein ^ρ _,' are Last estimated transmit power, "is the smoothing factor,

Estimate the transmit power for the open loop of the traffic channel,

And P satisfies the formula P ⁼ PDPCHdes + ^ Loss; where P, is a path loss value of the received signal,

^^ PH is the desired received power on this channel, ,, ρ, a PRX pppcHdes

And _s , and „PP Y„ _N ^ ^1K > DPCH-· Γ ΛΛ _PDPCHdes satisfies the formula 1 PDI'C;

Wherein, (S ^) _{D /} ' _C "is a desired received signal-to-interference ratio on the service channel, and is an interference power value on the current service channel.

5. The method according to claim 2, wherein the interference power value of the service channel is obtained by the following steps: For uplink power control, the interference power value of the uplink service channel is measured by the base station, and is sent to the cell through a system message. Internal broadcast; for downlink power control, the interference power of the downlink traffic channel is measured by the terminal and reported to the base station periodically.

6. The method according to claim 5, wherein the power control is uplink power control on the terminal side in a CDMA system, and the interference power value of the traffic channel is an uplink time slot interference signal code rate, and is determined by Steps to obtain: The base station periodically measures the interference signal code rate of the uplink time slot, and broadcasts the measurement result to the cell through a system message. After receiving the system message, the terminal uses the interference signal code rate carried in the message as the current service channel's Interference power value.

7. The method according to claim 1, wherein the step c) comprises the following steps:

Set a first predetermined threshold value and a second predetermined threshold value, and the magnitude relationship between the result greater than the comparison step b) and the first predetermined threshold value and the second predetermined threshold value, if obtained in step b) If the result is greater than the first predetermined threshold value, the power adjustment step size is increased by one step level; if the result obtained in step b) is less than the second predetermined threshold value, the power adjustment step size is decreased by one step level; if obtained in step b) As a result, the step size is unchanged between the first predetermined threshold value and the second predetermined threshold value.

8. The method according to claim 1, further comprising: setting a first predetermined threshold value and a second predetermined threshold value, and the greater than; Set a third predetermined threshold value A;

Step c) The method further includes: obtaining a path loss P _{SS of the} received signal; calculating an average value of the path loss estimation value of the latest predetermined times;

'Calculate the path loss value PL of the received signal. The absolute value of the difference between _ss and the average value of the most recent predetermined path loss estimation value ^γ = I ^PLOSS_ ^ I; the step c) is: comparing the absolute value ^{? / =} 1 ¹ ^ ^{5_ /} ^ with a third predetermined gate The magnitude relationship between the limits, and the magnitude relationship between the result obtained in step b) and the first predetermined threshold value A and the second predetermined threshold value,

If the result obtained in step b) is greater than the first predetermined threshold value or greater than the third predetermined threshold value ^, the power adjustment step size is increased by one step size level;

If the result obtained in step b) is less than the second predetermined threshold value and not greater than the third predetermined threshold value, the power adjustment step size is reduced by one step level.

If the result obtained in step b) is between the first predetermined threshold value and the second predetermined threshold value, and ^ is not greater than the third predetermined threshold value, the step size is unchanged.

.

9. The method according to claim 1, further comprising: setting more than one interval for the absolute value of the difference obtained in step b), each interval corresponding to a reference step size;

Is the path loss PL of the received signal. The average of _ss and the latest predetermined path loss estimate

The absolute value of the difference ^{Y =} \ ^ρ ^ ~ ^Ρμ \ sets more than one interval, each interval corresponds to a reference step;

Step c) further includes:

Get the path loss PL of the received signal. _SS ; Calculate the average of the path loss estimates for the last predetermined times ^;

Calculate the path loss of the received signal! The absolute value of the difference between ^ and the average value ^ of the most recent predetermined path loss estimate ^ = ^Y. ^ss ; obtain the reference step corresponding to the interval to which the value of current = \ ^{?> ss} ~ ^Pm I belongs;

Obtaining a reference step size corresponding to the interval to which the obtained result belongs;

A larger one is selected as the power adjustment step size from the obtained reference step sizes.

10. The method according to any one of claims 2, 8 or 9, wherein the path loss P _ss of the received signal is a beacon channel obtained by measuring a received beacon channel signal. Power fading value.

The method according to claim 10, wherein the beacon channel is a downlink pilot time slot or a main common control physical channel.

12. The method according to claim 1, characterized in that step d) comprises: extracting a transmission power control command from a currently received signal, and if the transmission power control command instructs to increase the terminal transmission power, determining according to step c) If the transmission power control command instructs to reduce the terminal transmission power, the transmission power is reduced according to the step determined in step c).

13. The method according to claim 1, characterized in that step d) comprises: comparing the magnitude relationship between the current transmission power estimated value obtained in step a) and the currently used transmission power value, if the current transmission power estimated value If the value is greater than the currently used transmission power value, the transmission power is increased according to the step size determined in step c); if the estimated value of the current transmission power is less than the currently used transmission power value, the transmission power is decreased according to the step size determined in step c).

14. A power control device for a time division duplex code division multiple access system, characterized in that it includes:

A control and calculation unit, configured to obtain a current transmission power estimate value from a signal received by the signal transceiver unit, and obtain a currently used transmission power through the power measurement unit; and calculate a currently used transmission power and a current transmission power estimation value The absolute value of the difference; the storage unit is configured to store the currently used transmission power value and the previous transmission power value; the power adjustment unit is configured to adjust the transmission power according to the calculation result of the control and calculation unit.

15. The device according to claim 14, further comprising: the control and calculation unit further comprising a loss deviation calculation module, configured to calculate an average value of the most recent predetermined path loss estimation value, and calculate a received signal The absolute value of the difference between the path loss of

The storage module also stores previously estimated path losses.