WO2004034605A1

WO2004034605A1 - A method and system of adaptive outerloop-power-control based on the measurement of ber

Info

Publication number: WO2004034605A1
Application number: PCT/CN2002/000849
Authority: WO
Inventors: Zhiyu Xu; Baijun Zhao
Original assignee: Utstarcom (China) Co., Ltd.
Priority date: 2002-09-26
Filing date: 2002-11-26
Publication date: 2004-04-22
Also published as: AU2002349456A1; CN100469182C; CN1486100A

Abstract

The present invention provides a method and a system of adaptive outer-loop-power-control based on the measurement of BER. The method comprises several steps as followed: measuring BER to obtain the measured value of BER at the front-end of a decoder; adjusting the object value of SIR depended on the measured value of BER; and comparing the object value to the measured value of BER, generating a control-power command. By using this method, the time of measurement should be reduced significantly during the process of the outer-loop-power-control. At the same time, the method is easy to be achieved, because it does not need to know the relationship between BER and SIR.

Description

A method based on bit error rate measurement

Adaptive outer loop power control method and system

The present invention relates to the field of mobile communications, and more particularly to an adaptive outer loop power control method and system based on bit error rate BER measurement in a third generation mobile communication system. Background technique

In direct spread spectrum/code division multiple access (DS/CDMA) mobile communication systems, conventional RAKE receivers require rigorous power control techniques to achieve satisfactory performance. In third-generation mobile communication systems, such as UMTS, WCDMA, cdma2000, etc., power control is divided into open loop power control and closed loop power control. Open loop control is a rough estimate of channel fading, while closed loop power control effectively tracks the fast fading of the signal. Closed loop power control consists of two parts: fast inner loop control and outer loop control. Fast inner loop control adjusts the transmit power of the user equipment (UE) through a series of power adjustment commands to achieve the current target signal-to-noise ratio (SIR). The outer loop power control allows the receiver to obtain appropriate performance metrics such as block error rate (BLER) and bit error rate (BER) by adjusting the target signal-to-noise ratio (SIR).

In "WCDMA for UMTS" by Harri Holma and Antti Toskala, John Wiley & Sons, 2001, the SIR target value needs to be adjusted according to the UE's moving speed and multipath fading environment. The greater the change in received power, the higher the SIR target value. If a fixed SIR target value is set, it is easy to make the communication quality too high or too low, resulting in unnecessary power boost and capacity loss. Therefore, the purpose of the outer loop power control is to provide the required quality: neither too bad nor too good. Too bad, can't satisfy the user's call quality; too good, it wastes capacity, and finally makes the network easy to be congested and the blocking rate is too high, which reduces the performance of the network. 1 is a process of implementing reverse closed loop power control in the prior art. The upstream receiver combines the received multipath signals through a rake receiver. The signals combined by the rake receiver are divided into two paths, one of which is deinterleaved and decoded by the deinterleaver 106 and the decoder 105, respectively. Interleaving/deinterleaving, also known as interleaving/deinterleaving, can be used to spread burst errors into random independent errors that are easily corrected by error correcting codes. The decoded signal measures the BLER or BER in the BLER/BER measurement unit 101 as an input parameter to the outer loop power control algorithm unit 102. The other way passes through the SIR measurer 104 for measuring the signal SIR to obtain the SIR measurement. The output parameter SIR target value of the outer loop power control algorithm unit 102 is then compared with the SIR measurement value in the comparator 103, and a power control command (TPC) is generated from the relationship between the two values. The TPC is sent to the UE through the common channel for uplink fast inner loop power control. For example, when the SIR measurement value > SIR target value, TPC = -1, that is, the UE is controlled to reduce the transmission power; when the SIR measurement value is <SIR target value, TPC = 1, that is, the UE is controlled to increase the transmission power.

The cyclic redundancy check code (CRC) is usually used to measure the correctness of the received target data block when measuring the BLER. The algorithm in the 3GPP (Third Generations Partnership Project) specification is that the base station controller updates the SIR target value every time it receives a data block. The specific algorithm is as follows:

IF CRC check OK

Step—down =BLER_target * Step— size;

SIR— target (n+1) = SIR target(n) - Step— down;

ELSE

Step_up= Step— size - BLER target * Step size;

SIR— target (n+1) = SIR— target(n) + Step one up;

END

Step-size is the step value of the target SIR adjustment. For example, ldB, BLER_target is the target BLER value of the user service. There are some other calculations For the method, refer to Chinese patents CN1357985 and CN1360410, which are based on the frame error rate (FER) and block error rate (BLER) as input parameters for the outer loop power control.

However, the above-mentioned use of BLER as an input parameter for outer loop power control causes problems in high-quality data (for example, BER = 1 (T ⁶ ) transmission required in 3GPP TS 23.107: "QoS Concept and Architecture". At low BER, the BLER is also very low, which requires a considerable amount of time to make accurate measurements. For example, for a service with a transmission rate of 32 kbit/s and a data frame of 80 ms (including interleaving depth), BER target value = 10 The target BLER value requirement is less than 10_ ^3. At this time, in order to obtain reliable measurement accuracy, the BLER measurement parameter is generally greater than 5000 frames, that is, 400 seconds. Such long measurement time is not in practical application. Therefore, for high quality services, some soft information may be needed, for example, intermediate BLER measurements in multi-cycle Turbo decoding or intermediate BLER measurements in convolutional codes and Reed-Solomon codes. See H. Kawai, H. Suda and F. Adachi,, Outer-loop control of target SIR for fast transmit power control in turbo-coded W-CDMA mobile radio", Electronics Letters, vol. 35, no. 9, pp. 699-701, Mar. 1999. However, these soft messages are optional parameters in the 3GPP standard, and wireless network controllers (RNCs) do not always have access to these soft messages.

Therefore, an outer loop power control algorithm is needed to solve the problem of long BLER measurement time under high quality traffic.

In addition, in G. Fredrik and B. Jonas's Improved performance using nonlinear components in power control algorithms ", VTC99, Vol. 2, 1999, pp 1276-1280, and G. Fredrik and B, Jonas's "Estimation and Outer" Loop power control in Cellular Radio Systems "ACM Wireless Networks, 2001 refers to an outer loop power control algorithm based on analyzing the nonlinear relationship between BER and SIR. But due to fading channels The difference in environment, plus the influence of coding and decoding, is a nonlinear relationship between BER and SIR. It is very complicated to obtain the determined relationship between them.

Therefore, an outer loop power control algorithm is needed, which does not need to know the exact relationship between BER and SIR to achieve effective outer loop power control. Summary of the invention

In view of the above problems in the prior art, the present invention provides an adaptive outer loop power control method based on BER measurement, comprising the following steps: a. measuring BER to obtain BER measurement value; b. based on measured BER value Adjusting the SIR target value; c. comparing the SIR target value with the SIR measurement and generating a power control command, the method being characterized in that the measuring step includes measuring the BER of the decoder front end and the present invention also provides a BER based The measured adaptive outer loop power control system comprises: a BER measuring device for obtaining a BER measurement value; an outer loop power control device for terminating the SIR target value according to the BER measurement value; and a comparator for the SIR target The value is compared to the SIR measurement and a power control command is generated. The system is characterized in that: the BER measuring device is located at the front end of the channel decoder.

In the above method and system, using the transmission channel BER (TrCH BER ) of the channel decoder front end to adjust the SIR target value, the measurement time can be significantly reduced, the channel variation can be quickly converged and tracked, and the previous block rate based BLER is overcome. The algorithm converges too slowly and is not easy to implement in high-quality services, so that the target SIR can be quickly adaptively adjusted to achieve neither BER nor BER performance.

In addition, the method is further based on the formula target SIR value,

"" is used to adjust the convergence speed of the method in different fading environments, and its value root According to the channel environment and the fading depth, SIRi, _n+1 is the SIR target value of the i-th user n + 1 times, Bi is the BER target value of the user, and SIRi, _min is the minimum SIR required for the user service. value. In a typical channel fading environment, "the value can be 1.

Based on this formula, another advantage of the method and system is that it does not need to know the specific relationship between BER and SIR, and overcomes the complexity of the existing outer loop power control algorithm based on analyzing the nonlinear relationship between BER and SIR. .

Thus, the method and system of the present invention can effectively achieve the goal of an outer loop power control algorithm: to obtain the desired BER and BLER with minimal transmit power. DRAWINGS

The above-described advantages and other advantages of the present invention will become more apparent from the detailed description of the invention. In the drawing:

1 is a block diagram of a prior art process for implementing a reverse closed loop power control; FIG. 2 is a block diagram of a process for implementing a reverse closed loop power control in accordance with the present invention;

3 is a flow chart for implementing a reverse closed loop power control process in accordance with the present invention;

4 is a flow chart for comparing the relationship between the BER measurement value and the BER target value; FIG. 5 is a flow chart for comparing the relationship between the SIR measurement value and the SIR target value; FIG. 6 is a case of channel coding and channelless coding. Coding gain comparison; Figure 7 shows the result of adjusting the SIR target value by the outer loop power control algorithm in accordance with the present invention;

Figure 8 shows the results of BER measurements in an outer loop power control algorithm in accordance with the present invention. Real body implementation Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the various figures, similar elements are numbered similarly. First preferred embodiment

2 is a block diagram of a process for implementing a reverse closed loop power control in accordance with the present invention. In Figure 2, a BER measurer 201 is placed at the front end of the decoder 205, i.e., the transmission channel BER (TrCH BER) is measured at the input of the decoder. The BER measurer 201 herein can be any of the BER measuring devices of the prior art. Although the figure shows that the BER measurer is located between the decoder and the deinterleaver, those skilled in the art will appreciate that the BER measurement unit can be located elsewhere in the decoder, enabling other locations for BER measurements, for example, when the BER measurer The BER measurement is obtained by regenerating the encoded data stream using a decoding and encoder to compare with the received interfered encoded data stream.

The transport channel BER is the result of an average BER measurement of a dedicated physical data channel (DPDCH) in a wireless connection, which refers to the BER parameter measured before the decoder in the case of coding. The measurement period is generally a transmission time interval (TTI). The TTI can be 10, 20, 40 or 80 ms. Different transport channels may use different TTIs.

The reason for measuring the BER at the input of the channel decoder is that they differ by a codec gain relative to the BER typically measured at the output of the channel decoder. For fixed decoders, such as convolutional codes and Turbo codes, the codec gain is relatively fixed and relatively easy to measure by simulation. Under fading channels, channel coding can significantly improve reception performance. 6, in the Rayleigh fading channel, at the same BER (eg 10_ ²⁾ performance, using a rate 1/2 convolutional code to obtain a receiver gain of 8dB codec receiver than without channel coding. Therefore, the difference between the codec gain of the input and output of the decoder is also used to solve the problem of high-quantity service BER measurement. When the need to measure the output of the decoder, for example, high-quality service BER = 1 (T ⁶ when, measurements may only need the input of the decoder corresponding to the BER = 1 (T ^2. Thus, for a transmission rate of 32kbit / s, The data frame is 80ms (including the interleaving depth). The 80ms TTI measurement interval can obtain the transmission channel BER measurement with a measurement error of ±4%, thus solving the high-quality service BLER/BER measurement of the normal outer loop power control algorithm. The problem of long time. It will be understood by those skilled in the art that the values given herein are merely exemplary, and they will vary according to the encoder and the channel. In addition, it should be noted that the measurement time interval is different according to different services. The transmission digital rate requirement and the accuracy of the BER measurement and measurement requirements are determined. Generally speaking, the larger the transmission digital rate, the shorter the measurement time, and the lower the BER value or the higher the measurement accuracy requirement, the measurement time The longer the interval.

The BER measurement result obtained from the BER measuring unit 210 is stored in the quality estimation (QE) field of the FP (frame protocol) frame. Node B transmits the uplink FP frame to the Outer Loop Power Control (OLPC) unit 202 located in the Radio Network Controller (RNC) via the lub interface, where reverse outer loop power control is performed.

After the SIR target value is obtained from the OLPC unit 202, the SIR measurement obtained from the SIR measurer 204 is compared in the comparator 203, thereby generating a power control command TPC, which is transmitted down to the UE for power control.

The workflow of the present invention will be described below with reference to FIG. First, the BER of the decoder front end is measured and transmitted to the OLPC unit 202 in step 310. Next, in step 320, the OLPC unit adjusts the SIR target value based on the relationship between the BER measurement and the desired BER target value. After passing the outer loop power control unit, if the SIR target value changes, the OLPC unit 202 notifies the node B of the new SIR target value via the lub FP control frame "uplink outer loop power control" signaling. In step 330, after node B obtains the SIR target value, it compares it with the SIR measurement measured by SIR measurer 204, thereby generating a TPC that controls the UE's transmit power.

The specific adjustment method in step 320 of FIG. 3 will be described below with reference to FIG. In the present In the art, in order to effectively perform BER-based power control, it is necessary to clearly understand the relationship between transmission power, SIR, and BER. The only thing currently known is that there is no linear relationship between BER and SIR, but an exponential relationship. For related content, see A. Sampath, PS Kumar and Jack M. Holtzman's On Setting Reverse Link Target SIR in a CDMA System ", VTC97, 1997. Many outer loop power control algorithms based on analyzing the nonlinear relationship between BER and SIR are Complicated. Complex algorithms can make the RNC processing time too long, thus reducing the accuracy and real-time performance of power control, and the present invention overcomes these shortcomings and can quickly converge and track channel changes.

In step 321 of Fig. 4, the OLPC obtains the BER measurement value, and then in step 322, the SIR target value is adjusted by comparing the relationship between the BER measurement value and the BER target value. Assume that the BER of the i-th user measured at the nth time is represented by BERi(n), and the target BER is represented by Bi, so the n + 1th SIR target value can be obtained according to the following formula:

Where SIRi, _min is the minimum SIR required for the current service of the i-th user. The lowest SIR in the formula is to ensure that the algorithm does not converge to zero. α is used to adjust the convergence speed of the algorithm in different fading environments. When “the larger the adjustment step is, the smaller the convergence is, the slower the convergence, but the smaller the amplitude of the SIR target is. The smaller the smaller the adjustment step is. Large, the faster the convergence, but the amplitude of the oscillation of the SIR target value is larger, resulting in greater interference in a short time. Typical values for a range from 1 to 3. In a district environment, there is often a case of deep fading, for example, 1 or 2, and in suburban and rural areas, where the fading variation is low, α may be, for example, 3. According to the above formula, the SIR target value Adjust the step size to la

In general, the value can be . In this case, the formula is reduced to

In digital communication, in the case of additive white Gaussian noise channel (AW GN) high signal-to-noise ratio, the relationship between SIR and BER is usually expressed using the formula BER=exp(-SIR)/2. Formula (2), which is further compressed into

Thus, the SIR target value can be adjusted based on the relationship between the BER target value and the actual BER measurement. The specific adjustments are as follows (see steps 3221 - 3223 in Figure 4):

1) If ΒΕ(η) = Βί, SIRi(n)=ln(l/2 Bi), SIRi, _n+ i=SIR _in

The SIR target value remains unchanged;

2) ^ BERi(n)<Bi, SIRi(n)>lii(l/2 Bi), SIR _i)n+ i= ^^SIR _i)n i

SIR^ri)

The SIR target value is lowered by a certain step size;

3) If BER^^Bi, SIRi(n)<ln(l/2 Bi), SIRi, „ ₊ i= ^) SIR _in

The SIR target value is increased by a certain step size. One of the advantages of this algorithm is that it can be adaptively adjusted according to the actual situation of the channel.

SIR step size. When the difference between the BER target value and the actual BER measurement is large,

SIR step

BER measurement from

The motion is reduced until the algorithm converges. The convergence between the BER target value and the actual BER measurement value is very close, and the SIR target value remains unchanged.

As can be seen from the above description, this algorithm does not need to know the specific relationship between BER and SIR, and it is relatively simple to implement. The complexity of the outer loop power control algorithm based on analyzing the nonlinear relationship between BER and SIR is overcome.

The specific operation in step 330 of Fig. 3 will be described below with reference to Fig. 5. After passing the outer loop power control algorithm, if the SIR target value changes, the OLPC unit 202 informs the node B through the Iub FP control frame "uplink outer loop power control" signaling. The target SIR value is then compared in comparator 203 with the SIR measurement obtained from SIR measurer 204. If the SIR measurement value > SIR target value, TPC = -1, it is necessary to control the UE to reduce the transmission power. If the SIR measurement value <SIR target value, TPC = +1, it is necessary to control the UE to increase the transmission power. Thus, the outer loop power control method of the present invention is completed.

The simulation results of the method of the present invention will be described below with reference to Figs. 7 and 8. 7 is a result of adjusting an SIR target value according to the outer loop power control method of the present invention, and FIG. 8 is a BER measurement result in the outer loop power control method according to the present invention. In Figure 7, the initial SIR target value is 7dB, the initial target BER measurement is 5*1 (T ⁵ , and the BER target value is 10Λ, that is, the current service is a high-quality data service; at the measurement time point η = (10, 20, 30, 40), due to sudden changes in the fading environment, The channel BER measurement suddenly changes: BER _n = ΒΕΙ^+ΑΙΟΛ 1 \ 10, 10 ² ); The parameter SIR deviation represents the standard deviation of the SIR target value (a logarithmic normal distribution of random variables) with a value of ldB. The time interval measurement unit in the figure is a TTI.

As can be seen from Figure 7, the outer loop power control method quickly adjusts the SIR target value to about 7.9 dB based on the difference between the BER target value and the BER measurement value, while the BER measurement value in Figure 8 is stable at 10- ⁶ nearby. When the BER measurement value changes drastically due to channel fading, as it is an order of magnitude smaller at n = 10, the power control method according to the present invention can quickly lower the SIR target value, thereby reducing the UE transmit power and reducing the other User interference. When the channel fading returns to its original state, the method can quickly track and increase the SIR target value to the original stable SIR value of 7.9 dB. Similarly, when the BER measurement value is n = 30, it is increased by an order of magnitude. According to the difference between the BER measurement value and the BER target value, the method increases the target SIR value, so that the UE increases the transmission power, thereby making the BER measurement value. Quickly narrow the gap with the BER target value and reduce the impact of the team's high quality data services. It should be noted here that the BER measurement in Figure 8 is calculated from the channel BER in the QE combined with the channel coding gain. This explains that at time points 10, 20, 31 and 41, the BER measurement will be as low as 10· ⁷ and 1 (Γ ⁸ orders of magnitude.

As can be seen from the above description, the present invention provides methods and systems for performing outer loop power control in high quality communications. It can reduce the measurement time of the outer loop power control under the premise of high shield business. It uses the BER measurement information in the quality estimation (QE) domain, that is, the transmission channel BER to adjust the SIR target value, which is easy to implement, can quickly converge and track channel changes, and can quickly and adaptively adjust the SIR target value to achieve not too bad, nor Too good "BER performance. Moreover, it does not need to know the specific relationship between BER and SIR, overcoming the complexity of the existing outer loop power control algorithm based on analyzing the nonlinear relationship between BER and SIR. Two preferred embodiments N2002/000849

In the first embodiment, the case where the RNC is separated from the Node B is described. The Node B needs to transmit the BER measurement value to the RNC through the Iub interface. If there is any change in the SIR target value, the RNC also needs to pass the corresponding signaling through the Iub interface. Notify node B.

However, for a system that adopts a centralized control mode, that is, a system in which the RNC and the Node B functions are concentrated in the Node B, it is not necessary to transmit various parameters between the Node B and the RNC through the Iub interface, and only the Node B itself is Outer loop power control is available. The manner in which it is implemented is similar to the implementation in the first embodiment, and will not be described here. Third preferred embodiment

The first and second embodiments of the present invention describe the uplink outer loop power control algorithm in Node B, which can also be similarly applied to the downlink outer loop power control calculation in the mobile station. At this time, the functions of the RNC and Node B are concentrated in the mobile station. The embodiment is similar to the embodiment of the first embodiment, and the same portions will not be described in detail, and only the differences will be described below.

In the mobile station service, the BER target value is notified to the mobile station after being set by the RNC. The mobile station measures the BER value according to the aforementioned method and adjusts the SIR target value according to the algorithm. The mobile station simultaneously measures the SIR of the received signal, and compares it with the SIR target value to obtain a downlink fast inner loop power control command, and then sends it to the node B for downlink power control. Fourth preferred embodiment

The present invention can also be implemented in the following manner when the quality requirements of the user service are not high. At this point, the system architecture shown in Figure 1 can still be employed, i.e., the BLER/BER is measured at the back end of the decoder, except that the outer loop power control unit 102 is replaced by the outer loop power control (OLPC) unit 202 of the present invention. In this case, if the measured parameter is BER, the outer ring according to the present invention can be directly implemented according to formula (1). Power control method. If the measured parameter is BLER, then a scaling device is needed to convert the BLER value to the BER value in some way before performing the subsequent operations. Subsequent operations are the same as those described in the first embodiment and will not be described in detail herein. The invention has been described in detail above on the basis of preferred embodiments. Although the preferred embodiment is described in terms of a logarithmic relationship between BER measurements and BER target values, those skilled in the art will appreciate that other relationships between BER measurements and BER target values can also be used to implement the present invention, for example , use the exponential relationship between them or use recursive methods.

Although the preferred embodiment of the present invention describes the implementation of outer loop power control based on equations (1)-(3), those skilled in the art will appreciate that the control can also be implemented in other ways, for example, through a program. , look up the table or through the combination of software and hardware.

In the present invention, the user equipment UE may be any user equipment having a wireless access function, including but not limited to a mobile phone, a portable computer, a personal digital assistant, and the like. Although the invention is illustrated in a preferred embodiment of the invention for use in a DS/CDMA system, the invention is also applicable to all systems requiring outer loop power control, including but not limited to IS95 systems, WCDMA systems, TD-SCDMA, and Cdma2000 system, etc.

Although the invention has been described in terms of the preferred embodiments thereof, these descriptions are only for the purpose of illustration and should not be construed as limiting. A person skilled in the art can make various modifications and improvements to the present invention, and these modifications and improvements are included in the scope and spirit of the invention as defined in the appended claims.

Claims

Claims An adaptive outer loop power control method based on BER measurement, including the following: a. Measuring BER to obtain BER measurements;

B- adjust the SIR target value based on the measured BER value;

c. Comparing the SIR target value with the SIR measurement and generating a power control command, the method is characterized in that the step of measuring the BER comprises the step of measuring the BER at the front end of the decoder.

2. Method according to claim 1, characterized in that said step b adjusts the target SIR based on the following formula:

Adjusting the convergence speed of the method in the same fading environment, the value varies according to the channel environment and the fading depth. SI, _n+1 is the SIR target value of the i-th user n + 1 time, and Bi is the BER target of the user. The value, SIRi, _min is the minimum SIR value required for the user's business.

3. Method according to claim 2, characterized in that the step size of the SIR target value adjustment is I a ■ SIR

4. The method according to claim 2, wherein when α = 1, the above formula is rounded to step b at this time as follows

Way to adjust the target SIR: 1) If ΒΕ (η) = B _i}

, the SIR target value remains unchanged;

2) If ΒΕ (ϋ)<Βί SIRi(n)>In(l/2 B , SIR _{i n+} i= ln(l/2J5,.) _SIR

SIR^ri)

SIR target value is lowered; and

3) If BERI(n)>Bi , SIRi(n)<ln(l/2 B , SIR _{i n+1} = ^1η ( '1⁄2 , _η ,

The SIR target value is raised.

The method according to any one of claims 1 to 4, wherein: the step c is compared based on the following manner: if the SIR measurement value > the SIR target value, the power control command is set to -1, which is required The UE is controlled to reduce the transmission power. If the SIR measurement value is <SIR target value, the power control command TPC=+1 is performed, and the UE needs to be controlled to increase the transmission power.

6. The method according to claim 2, wherein: the SIR target value is required to be greater than a minimum SIR value of the service

7. Method according to claim 1, characterized in that step b is done in the radio network controller RNC.

8. The method according to claim 7, wherein: the BER measurement obtained at the front end of the channel decoder is transmitted by the Node B to the RNC through the lub interface through the quality estimation domain of the uplink FP frame.

9. The method according to claim 8, wherein: if the SIR target value obtained in the RNC changes, the RNC notifies the Node B through the lub interface through the FP control frame "Upper Loop Power Control" signaling.

10. An adaptive outer loop power control system based on BER measurement, comprising: a BER measuring device for obtaining BER measurements,

An outer loop power control device for adjusting the SIR target value according to the BER; a comparator for comparing the SIR target value with the SIR measurement value and generating a power control command,

The system is characterized in that: said BER measuring device is located at the front end of the channel decoder.

11. The system of claim 10, wherein the outer loop power control device is configured to adjust the target SIR based on the following formula:

"" is used to adjust the convergence speed of the method in different fading environments, and its value varies according to the channel environment and the fading depth. SIRi, _n+1 is the SIR target value of the i-th user n + 1 times, Bi is The user's BER target value, SIRi, _min, is the minimum SIR value required for the user's service.

12. The system according to claim 11, wherein the outer loop power control device adjusts the SIR target value by a step size of la SIR,

13. The system according to claim 11, characterized in that, when "1", the above formula is cylindricalized into the outer ring at this time.

The power control device is configured to adjust the target SIR in the following manner:

1) If ΒΕ (ιι) = Bi,

, the SIR target value remains unchanged;

2) If ΒΕ (η) <Βί, SIRi (n)> In (l / 2 B, SIR i n + i = l¾ IRin,, SIR target value is lowered; and

3) If ΒΕ (ϋ)>Βί , SIRi(n)<ln(l/2 B ,

The SIR target value is raised.

14. A system according to any one of claims 10 - 13, characterized in that the comparator is configured to compare based on: If the SIR measurement > 8111 target value, then the power control command =- 1. It is necessary to control the UE to reduce the transmission power; if the SIR measurement value <SIR target value, the power control command TPO+1 is required, and the UE needs to be controlled to increase the transmission power.

15. The system according to claim 11, wherein: the system requires that the SIR target value be greater than a minimum SIR value of the service.

16. System according to claim 10, characterized in that the outer loop power control device is located in the radio network controller RNC.

17. The system of claim 16 wherein: the BER measurer transmits the BER measurement to the RNC via the lub interface through the quality estimation field of the uplink FP frame.

18. The system according to claim 17, wherein: if the SIR target value obtained in the RNC changes, the RNC notifies the Node B through the FP control frame outer loop power control "signaling" through the lub interface.

19. An adaptive outer loop power control method based on BER measurement, comprising the following steps:

A- measure the BER to obtain the BER measurement;

B- adjust the SIR target value based on the measured BER value;

c Compare the SIR target value with the SIR measurement and generate a power control command characterized by:

The step b is implemented based on the following formula:

"" is used to adjust the convergence speed of the method in different fading environments, and its value varies according to the channel environment and the fading depth. SIRi, _n+1 is the SIR target value of the i-th user n + 1 times, Bi is The user's BER target value,

Is the minimum SIR value required for this user's business.

20. The method according to claim 19, wherein in the step a, if the block error rate BLER value is measured, it can be converted into a BER value first.

21. An adaptive outer loop power control system based on BER measurement, comprising: a BER measuring device for obtaining BER measurements,

An outer loop power control device for adjusting an SIR target value according to a BER; and a comparator for comparing the SIR target value with the SIR measurement value and generating a power control command, wherein:

The outer loop power control device is configured to adjust the target based on the following formula

SIR target value:

"" is used to adjust the convergence speed of the method in different fading environments, and its value varies according to the channel environment and the fading depth. SIRi, _n+1 is the SIR value of the i-th user n + 1 times, Bi Is the BER target value of the user, SIRi, _min is the minimum SIR value required for the user's service.

22. The method according to claim 21, wherein: said BER measuring device comprises a BLER measuring device and a scaling device, said scaling device for converting the measured block error rate BLER value to a BER value.