WO2005067167A1

WO2005067167A1 - Forward power control method in cdma system

Info

Publication number: WO2005067167A1
Application number: PCT/CN2005/000011
Authority: WO
Inventors: Zhouyu Deng
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2004-01-01
Filing date: 2005-01-04
Publication date: 2005-07-21
Also published as: CN100362764C; CN1642033A

Abstract

The present invention discloses a forward power control method in CDMA system, descent stepsize of forward transmission power has been set in advance using the said method, and performing the following step: starting a clearing-zero timer of frame amount counter; waiting for Power Measurement Report Message (PMRM) transmitted by Mobile Station (MS) during timing, and calculating raise stepsize in accordance with the PMRM transmitted by MS and the descent stepsize set in advance if the MS has transmitted the PMRM, then improving forward transmission power in accordance with calculated raise stepsize, and restarting the clearing-zero timer of frame amount counter; reducing forward transmission power in accordance with set descent stepsize if the clearing-zero timer of frame amount counter is overtime, and restarting the clearing-zero timer of frame amount counter. According to the method of the present invention, the size of raise stepsize can be changed in accordance with measurement report and relevant parameters, realizing rapid and exact adjustment of the forward transmission power to ensure the convergence of forward power and frame error ratio (FER).

Description

Forward power control method of code division multiple access system

Technical field

The present invention relates to a power control method of a code division multiple access system, and particularly to a forward power control method of a code division multiple access system. Background of the invention

The forward power control of a Code Division Multiple Access (Code Division Multiple Access, "CDMA") system mainly refers to the control of the base station's transmit power, and is usually reported by the Base Station Controller ("BSC") according to the mobile station. Power Measurement Report Message ("PMRM" for short) to complete.

A mobile station usually reports PMRM in two modes: one is a periodic mode in which the mobile station reports PMRM at a fixed time slot; the other is a threshold mode in which the mobile station reports PMRM when the number of received error frames reaches the threshold specified by ij. Because the threshold mode saves the air interface resources of the CDMA system than the periodic mode, it is often used in practical applications.

In the threshold mode, the mobile station is provided with a total frame counter and a frame error counter, which are respectively used to count the total number of frames and frame errors received by the mobile station on the forward basic channel. The total frame counter is a loop counter. When the counter reaches the set counting period, the mobile station will automatically clear its own counter and the errored frame counter, and immediately start counting again from zero.

In addition to the above-mentioned automatic clearing operation, after reporting PMRM, the mobile station will also clear the total frame counter and the error frame counter, but in order to avoid frequent power adjustments, the counter does not start immediately after clearing Counting for one cycle, but delaying for a period of time before starting counting.

In the threshold mode, the mobile station determines the reporting timing according to the value of the frame error counter. According to the protocol, when the count value of the errored frame counter is equal to the reporting threshold issued by the base station to the mobile station, the mobile station will send a PMRM to the BSC, and include the values of the total frame counter and the errored frame counter in the PMRM. The BSC performs forward power control according to the total number of frames and the number of errored frames reported by the mobile station. Figure 1 shows the steps of the aforementioned BSC to perform forward power control through PMRM:

Step 101: The BSC starts a waiting measurement report timer after the basic channel is established.

The waiting measurement report timer is used to determine the timing for the BSC to lower the forward transmission power. When the timer expires, the BSC lowers the forward transmission power once according to the set falling step. The duration of the waiting measurement report timer is set by those skilled in the art according to empirical values, and the duration is not associated with a counter on the mobile station side.

Step 102: In the process of waiting for the measurement report timer, the BSC waits for the mobile station to report PMRM. If the mobile station reports PMRM, then step 103 is performed; if the waiting measurement report timer expires and the mobile station does not report PMRM, then step 106 is performed. .

Step 103: Stop waiting for the measurement report timer, and calculate the current frame error rate (FER) of the mobile station according to the PMRM content.

Step 104: Compare the calculated FER with a preset target FER set by the BSC. If the calculated FER is greater than the target FER, go to step 105; otherwise, go to step 106; where the target FER is determined according to the requirements of the system and the protocol .

Step 105: The BSC increases the forward power by a rising step size, restarts the waiting measurement report timer, and then returns to step 102.

Step 106: The BSC reduces the forward power by a falling step, restarts the waiting measurement report timer, and then returns to step 102.

It should be noted that both the ascending step and the descending step are set by a person skilled in the art according to the transdermal value, and the ascending step and the descending step are independent and there is no restriction relationship between them. The foregoing forward power control method using the threshold mode can dynamically adjust the forward transmission power according to the frame error rate of the current mobile station receiving data frames, but in practical applications, this method cannot also be fast and stable according to the data frame quality. The forward power is adjusted, and the convergence of the forward power and FER cannot be guaranteed.

The main reason for the above situation is: In the prior art, the rising step and falling step of adjusting the forward transmission power are fixed. Therefore, the rise and fall of the power can only be determined according to the FER in PMRM, but not the total number of frames. The difference between the two increases and decreases. For example, if the target FER is also set to 2%, when the total number of frames is 2 and the number of error frames is 2, the algorithm decides to increase by one step; when the total number of frames is 100 and the number of error frames is 2, the algorithm also decides By increasing the same step size, the above-mentioned forward power adjustment is either inferior to the leaf, or due to the excessive adjustment, the forward transmission power and the sharp fluctuation of FER are generated.

In addition, in the prior art, the ascending and descending steps are set separately, which makes there is no mutual restriction between the ascending and descending steps and the target FER. If the configuration is improper, it will cause forward transmission. Power and adjusted FER cannot converge to a fixed value.

Also, in the prior art, the physical meaning of the waiting measurement report timer duration is ambiguous and has no relationship with the threshold of the total frame counter on the mobile station side, so it cannot be known that the total frame counter of the mobile station is automatically cleared. Zero information cannot be synchronized with the total frame counter of the mobile station, which will cause the BSC to not reduce the forward transmission power in a timely or too fast manner, and will also cause the forward power adjustment to be either untimely or fluctuating violently. Summary of the invention

In order to solve the above technical problem, the present invention provides a forward power control method of a code division multiple access system, which realizes variable step size adjustment of the forward power, so that the code division multiple access system can quickly ensure the quality of the forward transmission while rapidly The power is regulated steadily, and the forward transmission power and the frame error rate received by the mobile station are converged. The forward power control method of a code division multiple access system according to the present invention includes the following steps: a. Starting a timer for clearing a total frame counter;

b. During the counting process of the total frame counter reset timer, waiting for a power measurement report message on the mobile station, if a power measurement report message on the mobile station is received, proceed to step c; if the total frame counter is cleared The timer expires, then go to step d;

c. Calculate the rising step size of the forward transmission power based on the power measurement report message reported by the mobile station and the preset step size of the forward transmission power decrease, increase the forward transmission power according to the calculated rising step size, and restart the total number of frames The counter clears the timer, and then returns to step b; d. Reduces the forward transmission power according to a preset falling step, and restarts the total frame counter clear timer, and then returns to step b.

The calculation of the rising step size described in step c uses the following formula:

_{T TC} W P + W D-Fx P-Fx D ^

US = ~ = —- x DS

TxF-W_T

Among them, US is the step size of the forward transmission power increase; DS is the preset step size of the forward transmission power drop; F is the preset target frame error rate; P is the power measurement report: reported by Xiao Xi Total number of frames; W-P is the number of errored frames reported in the power measurement report message; D is the number of frames counted by the mobile station total counter delay; W-D is the number of errored frames during the delay count, which is based on the actual operation of the system The experience value set by the situation; T is the total number of frames in the counting period of the mobile station total frame counter; W_T is the average number of error frames in the counter period of the total number of frames for which no power measurement report message is reported, and is set according to the actual operating conditions of the system Experience value.

The number of errored frames W-D during the delay counting period according to the present invention is zero.

Before starting the frame total counter reset timer in step a, the method further includes: setting a counting duration of the frame total counter clear timer to a total number of frames of a counting period of the mobile station frame total counter;

Before restarting the total count counter clear timer described in step c, the method further includes: Setting the counting duration of the frame total counter clear timer to the sum of the total number of frames in the counting period of the mobile station total frame counter and the number of frames counted by the mobile station frame total counter delay;

Before restarting the frame total counter reset timer in step d, the method further includes: setting a counting duration of the frame total counter clear timer to a total number of frames of a counting cycle of the mobile station frame total counter.

A fixed forward transmission power step-up is set in advance, and increasing the forward transmission power according to the calculated step-up in step c further includes:

cl. Compare the calculated rising step size with a preset fixed rising step size, and determine the calculated rising step size divided by the preset fixed rising step size to obtain a multiple N;

c2. According to the multiple N determined in step cl, the forward transmission power is continuously increased N times according to a preset fixed rising step size.

The timer for clearing the total number of frames of the present invention is counted in a decreasing manner;

In step b, the timer for clearing the total frame counter expires and the timer of the timer for clearing the total frame counter is decremented to zero.

By applying the forward power control method of the present invention, the following beneficial effects can be obtained: First, because in the method of the present invention, the rising step size can be changed according to the content of the measurement report, so it can be more quickly based on The system needs to adjust the forward transmission power in a timely manner, and quickly adjust the forward transmission power to the required range to ensure the quality of service provided by the system to users. For example, when encountering a large fading, the method of the present invention can quickly increase the step size, supplement the fading, and improve the transmission quality; and when the wireless environment is relatively stable, the method of the present invention can fine-tune the power , To ensure the stability of power.

Secondly, in the method of the present invention, the rising step size and the falling step size can be related to each other, and it is ensured that the forward transmission power and FER can be quickly converged under the condition that the falling step size is flexibly configured.

Third, the method of the present invention sets a timer for clearing the total number of frames in the BSC to clear the timer. Simulate the timing of the automatic clearing of the total frame counter of the mobile station to ensure that when the mobile station † J¾ total count is automatically cleared, the BSC frame total counter clear timer is synchronized to exceed, so as to achieve more accurate and timely forward power. control. Brief description of the drawings

FIG. 1 is a flowchart of a forward power control method based on a measurement report in an existing CDMA system;

2 is a flowchart of a forward power control method based on a measurement report in a code division multiple access system according to a preferred embodiment of the present invention;

FIG. 3 is a schematic diagram of a power control optimization algorithm model based on a measurement report in a code division multiple access system according to a preferred embodiment of the present invention. Mode of Carrying Out the Invention

To make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings.

In order to obtain the information of automatic clearing of the total frame counter on the mobile station side, and to solve the problems caused by reporting the PMRM by using the threshold mode in the prior art, the method of the present invention sets a counter for simulating the total frame number of the mobile station in the BSC. The timing of the clearing of the total frame counter of the automatic station clears the analog timer, which is simply referred to as the total frame counter clear timer. At the same time, in order to make the transmission power and FER converge faster in the process of power control, the method described in the present invention also proposes a power control optimization algorithm model that is compatible with the process of the present invention and a variable rising step based on the model. Long calculation method.

The following describes in detail a method for setting the duration of the frame totalizer clear timer with reference to a preferred embodiment of the present invention. Because the frame total counter reset timer is used to simulate the timing of clearing the mobile station total frame counter, the duration of the timer should be equal to the mobile The period of the total station counter counts the total number of frames, that is, when the leafr times out, it should be when the mobile station total counter is cleared. However, it is considered that in the prior art, the mobile station is reporting

After PMRM, the counting of the next cycle does not start immediately, but it starts after a period of time. Therefore, the total number of frames in the cycle statistics at this time is equivalent to the total number of frames and movement of the counting period of the mobile station frame counter. The sum of the number of frame delay counters. Therefore, the frame total counter reset timer according to the present invention has two corresponding durations: after the frame total counter clear timer expires, restarting the frame total counter clear setter and setting its timing duration For shift

PWR—REP— FRAMES The total number of frames in the counting period of the total frame counter, that is, 5 X according to the inch resolution.

Frame, where PWR_REP_FRAMES is the period reporting parameter issued by the base station to the mobile station; and after receiving the measurement report, the frame total counter reset timer is restarted, and its timing duration is set to be The sum of the total number of frames in the counting period and the number of mobile counter delay count frames. According to the protocol, the number of delayed count frames is 4 times the PWR_REP_ DELAY frame, where PWR_REP_ DELAY is the delay sent by the base station to the mobile station. Parameters, so

PWR REP FRAMES

At this time, the duration of the timer is 5 X 2 ~ "+ 4 X PWR_REP_DELAY frames.

After the above-mentioned frame total counter reset timer can be synchronized and timed out when the mobile station's total frame counter is automatically cleared, in order to achieve the purpose of simulating the mobile station's frame total counter reset timing, realizing timely and accurate Forward transmission power is adjusted down.

FIG. 2 shows a PMRM-based forward power control method flow in a code division multiple access system according to the present invention. In the method of the present invention, a step size of the forward transmission power is set in advance, and the step size is set by a person skilled in the art according to factors such as the system environment and transmission quality requirements. As shown in FIG. 2, the method according to the present invention includes the following steps:

Step 201: After the basic channel is established, the BSC starts a timer for clearing the total number of frames, and clears the timer for the total number of frames according to the timer setting principle described above.

PWR—REP— The duration of the FRAMES is set to the counting period of the mobile station total frame counter. The total number of frames is 5 X 2 ~~ ^ frame.

Step 202: During the counting of the frame count counter clear timer, the BSC waits for the mobile station to report PMRM. If the mobile station reports PMRM, it proceeds to step 203; if the frame count counter clear timer expires, the mobile station does not report PMRM, go to step 205.

In a preferred embodiment of the present invention, the frame total counter clearing timer may be counted down. If the timer is decremented from the preset counting time to 0, the timer may be judged to have timed out.

Step 203: The BSC stops the frame count counter reset timer, calculates the rising step size according to the total number of frames and the number of error frames reported by the mobile station, and increases the forward transmission power according to the calculation result.

The calculation method of the rising step size in this step will be described in detail below.

Step 204: The BSC restarts the total counter reset timer, and sets the duration of the timer to the total number of frames in the counting period of the mobile station total frame counter and the mobile station delay count frame.

PWR—REP— FRAMES

The sum of the numbers is 5x2 2 + 4xPWR— REP— DELAY frames, and then returns to step 202.

Step 205: The BSC stops the timer for clearing the total number of frames, and reduces the forward transmission power by a falling step according to a predetermined falling step.

Step 206: The BSC restarts the timer for clearing the total number of frames and sets the timer.

PWR_REP— FRAMES

The time length is the total number of frames of the counting period of the mobile station frame counter 5 X frames, and then returns to step 202.

The above steps 201 to 206 constitute a cycle, that is, when the number of error frames is equal to the threshold of the number of error frames, the mobile station reports PMRM to BSC, and BSC ^^ increases or maintains the forward transmission power according to the FER at this time, and reduces the mobile station's Receive a FER so that it is less than or equal to the target FER; and when the total frame counter clear timer expires, it indicates that the number of error frames within a predetermined time is within a predetermined threshold Within, the forward power currently used may exceed actual needs, and the forward transmit power should be appropriately reduced to increase the receiving FER of the mobile station. After reducing the forward transmission power one or more times, the received average FER is made close to the target FER until the mobile station reports PMRM again. After the above-mentioned cyclic process of increasing and decreasing the forward transmission power, the receiving FER of the mobile station is kept close to the target FER, and the convergence from the FER to the target FER is achieved.

On the other hand, in this embodiment, by controlling the timing duration of the frame count counter clear timer, the timing of the forward transmission power rising and falling corresponds to the timing of clearing the mobile station frame total timer to achieve accurate forward transmission power. Down.

The calculation method of the rising step size described in step 203 will be described in detail below.

In order to achieve power convergence and FER convergence in the power control process, the present invention proposes a power control optimization algorithm model based on a measurement report and a rising step size calculation method based on the model. The power control optimization algorithm model is established according to the power convergence principle and the FER convergence principle.

The power convergence principle refers to: During the mobile station's forward power control for a period of time, the amplitude of the BSC increasing the forward transmission power should be equal to the total amplitude value of the forward transmission power reduced one or more times by the BSC. Its mathematical expression is shown in formula (1):

US = NxDS (1)

Among them, US is the rising step size of the forward transmission power of the BSC;

DS is the step size for BSC forward transmission power reduction;

The number of times the timer has timed out to clear the BSC-side frame total counter between the mobile station's two PMR reports, that is, the number of times the BSC reduces the forward transmit power between the mobile station's two PMRM reports.

The FER convergence principle means that during a period of power control of the mobile station, the actual forward FER of the call calculated by the BSC should be equal to the target FER. Its mathematical expression is shown in formula (2): W_P + W_D + N x W_T _p ( ₂ )

P + D + NxT one

Among them, F is the target FER set by BSC;

P is the total number of frames reported in PMRM, W_P is the number of error frames reported in PMRM; D is the total number of mobile station frame counter counter count frames, and its value is 4 times PWR_REP_ DELAY, errored frames during this period The number is W-D;

PWR—REP— FRAMES

T is the total number of frames in the counting period of the mobile station's total frame counter, and its value is 5 X. The average number of errored frames during the period when PMRM is not reported is W-T, and because PMRM is not triggered, W-T- must be less than W- P.

The above-mentioned measurement control-based power control optimization algorithm model is shown in Figure 3. Figure 3 shows the process of the BSC increasing and decreasing the forward transmission power during the time when the mobile station performs PMRM twice. As shown in FIG. 3, in the above process, the total number of frames received by the mobile station on the forward basic channel is P + D + NXT, and the number of error frames therein should be W_P + W—D + NXW-T, such as As shown by the small box in Fig. 3, at this time, the average FER is W_P + W_D + xW_T.

P + D + Nx T

It can also be seen from FIG. 3 that after the mobile station reports the PMRM message, the BSC increases the forward transmission power and when the frame count counter clear timer expires, that is, when the frame count counter of the mobile station is cleared, Reduce the forward transmit power one or more times.

According to the content mentioned above, if the forward transmission power is to be converged, it is necessary to ensure that the increased power value and the reduced total power value of the BSC during the above-mentioned cycle are equal, which is to implement formula (1); if it is to achieve FER To converge, it is necessary to ensure that the average FER is equal to the target FER during the above-mentioned loop process, that is, to implement formula (2). Therefore, the power control optimization algorithm shown in Fig. 3 can achieve both transmission power convergence and FER convergence.

Combining formula (1) and formula (2), eliminating the variable N in the formula, the relationship between the rising step size and the falling step size can be derived, as shown in formula (3): _TT . W P + W D-FxP-FxD ^. ^,

US = ~~ = = xDS {3)

TxF-W_T

Among them, the number of errored frames W-D during the delay period of the total frame counter and the average number of frame errors W-T when the total frame counter is cleared can be estimated based on experience. Therefore, the formula (3) can be used to derive the size of the rising step US according to the total number of frames P and the number of error frames W_P reported by the mobile station, given the falling step DS.

In addition, from the above analysis, it can be seen that if the rising step and falling steps that satisfy the relationship of formula (3) are used in the process of power control, the transmission power convergence and FER convergence can be achieved.

Those skilled in the art can understand that the method for forward power control of the variable rising step size proposed by the present invention can also be replaced by a method of changing the power control frequency by fixing the rising step size. For example, when the rising step size calculated by the above method is relatively large, the calculated rising step size and the fixed rising step size may be first compared to determine the calculated rising step size divided by a multiple N of the fixed rising step size; Then, according to the determined multiple N, the forward transmission power is continuously increased N times at a faster frequency in accordance with a preset rising step size, and the same effect as that of the method of the present invention can be obtained, while avoiding the Sudden change in transmit power.

Those skilled in the art can also understand that, for the relationship formula (3) of the rising and falling step lengths, the simplified formula can be substituted by simplifying the parameters. For example, to simplify the calculation, W_D may be set to 0, that is, the number of error frames during the delay period of the total frame counter is 0, without exceeding the scope of the present invention.

It can be found through comparison that the technical solution of the present invention is different from the prior art in that, first, the forward power control method based on the measurement report in the code division multiple access system proposed by the present invention is cleared by setting a total frame counter on the BSC side. The timer simulates the total frame counter on the mobile station side, thereby obtaining the information that the total frame counter on the mobile station side is cleared, and realizes the forward transmission function. Timely and accurate adjustment of the rate; Secondly, the ascending step size in the solution of the present invention is variable, and the ascending step size can be determined according to the measurement report and related parameters, so as to achieve rapid and accurate adjustment of the forward transmission power; third, The solution of the present invention obtains the relationship between the rising step size and the falling step size according to the power convergence principle and the FER convergence principle, thereby ensuring fast convergence of the forward power and the FER.

Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, those skilled in the art should understand that various changes can be made in form and details, and Without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

Claim

1. A forward power control method for a code division multiple access system, characterized in that it includes the following steps:

a. Start the total frame counter clear timer;

b. During the counting of the total frame counter reset timer, wait for the mobile station to report a power measurement report message, and if the power measurement report message reported by the mobile station is received, proceed to step c; if the total frame counter clear timer expires, Then go to step d;

2. The forward power control method for a code division multiple access system according to claim 1, wherein the calculation of the rising step size in step c uses the following formula:

_TT . W P + W D-FxP-FxD ^ _c

US =-"" = xDS

TxF-W—T

Among them, US is the rising step size of forward transmission power; DS is the preset step size of forward transmitting power drop; F is the preset target frame error rate; P is the total number of frames reported in the power measurement report message. WJP is the number of errored frames reported in the power measurement report message; D is the number of frames counted by the mobile station total counter delay; W-D is the number of errored frames during the delay count, which is based on the experience set by the actual operating conditions of the system Value; T is the total number of frames in the counting period of the mobile station total frame counter; W_T is the average number of errored frames in the period of the total frame counter of the unreported power measurement report message, which is an empirical value set according to the actual operation of the system.

3. The forward power control method for a code division multiple access system according to claim 2, wherein the number of errored frames W-D during the delay counting period is zero.

4. The forward power control method for a code division multiple access system according to claim 1, further comprising: before starting the frame total counter reset timer in step a, setting the frame total counter clear. The timer duration is the total number of frames in the counting period of the mobile station total frame counter;

Before restarting the frame total counter reset timer described in step c, the method further includes: setting a counting time of the frame total counter clear timer to a counting period of the mobile station total frame counter and a total number of mobile frame counters Sum of frames counted by delay;

5. The forward power control method for a code division multiple access system according to claim 1, wherein a fixed forward transmission power step-up step is set in advance, and the calculated step-up step in step c is increased before The transmit power further includes:

c2 According to the multiple N determined in step cl, the forward transmission power is continuously increased N times according to a preset fixed rising step size.

6. The forward power control method for a code division multiple access system according to claim 1, wherein the frame total counter clear timer is counted in a decreasing manner;