CN100367685C

CN100367685C - Method for improving outer ring power control performance under multi-service circumstances

Info

Publication number: CN100367685C
Application number: CNB2005100244721A
Authority: CN
Inventors: 张严
Original assignee: Spreadtrum Communications Shanghai Co Ltd
Current assignee: Xiamen Ziguang Exhibition Rui Technology Co Ltd
Priority date: 2005-03-18
Filing date: 2005-03-18
Publication date: 2008-02-06
Anticipated expiration: 2025-03-18
Also published as: CN1665156A

Abstract

The present invention provides a method for improving outer ring power controlling performance under the condition of multiple services. The method comprises the following steps: step A, firstly, selecting a transmission channel as a referential transmission channel for outer ring power control; step B, carrying out outer ring power control for the referential transmission channel and simultaneously estimating the transmission channel block error rate of other transmission channels; step C, judging whether the outer ring power control of the referential transmission channel is converged, and judging whether the quality estimation of other transmission channels basically satisfies a corresponding quality objective value if the outer ring power control is converged; step D, keeping a rate adaption attribute value corresponding to each transmission channel unchanged if the quality estimation satisfies the corresponding quality objective value. If the quality of one or more services in other transmission channels is slightly better or worse, rate adaption attribute values corresponding to the transmission channels are regulated, and the rate adaption attribute values of transmission channels with slightly worse quality are increased; the rate adaption attribute values of transmission channels with slightly better quality are reduced. The method ensures the QoS requirement of all services for users by altering corresponding rate adaption attributes of the transmission channels, and therefore, the present invention has the advantages of reducing the waste of power resources and improving the capacity of a system.

Description

Method for improving outer loop power control performance under multi-service condition

Technical Field

The present invention relates to a power control method in a Code Division Multiple Access (CDMA) mobile communication system, and more particularly, to a method for improving outer loop power control performance under a multi-service condition.

Background

The CDMA mobile communication system is a self-interference system, namely, the increase of the power of one user will also increase the interference to other users, and the aim of introducing the outer loop power control is to ensure the quality of service (QoS) of the user by using the minimum power resource, avoid the waste of the power resource, reduce the interference to other users and improve the system capacity.

The basic principle of the outer loop power control is to determine the target value of the signal-to-interference ratio of the inner loop power control by comparing the actually estimated or monitored service quality (such as the block error rate or the bit error rate) with the service quality requested by the user (such as the target value of the block error rate or the bit error rate), so as to achieve the purpose of meeting the service quality required by the user.

The basic method of Outer Loop Power Control (OLPC) is shown in fig. 1, where the quality of the received signal is generally expressed by the block error rate (BLER) of the transport channel (TrCH), OLPC first sets an initial target value of the signal-to-interference ratio (SIRtarget), then estimates the BLER (block error rate) of the corresponding TrCH, i.e. the estimated value of the block error rate of the transport channel (BLERest), comparing with a block error rate target value (BLERTarget) given by an upper layer, if BLERRest (estimated value of the block error rate of a transmission channel) is less than the BLERTarget (target value of the block error rate), which shows that the actual service quality is better than the target value and power waste exists, reducing SIRtarget (target value of signal to interference ratio) of Inner Loop Power Control (ILPC); if BLERRest is greater than BLERTarget, which indicates that the actual QoS is lower than the target value, the SIRtarget of ILPC is increased. The relationship between OLPC and ILPC is shown in fig. 2, and the basic method of ILPC is that the receiving end compares the measured/estimated signal-to-interference ratio (SIRest) of the received signal with SIRtarget, and if SIRest < SIRtarget, a power adjustment command (called TPC) is sent to increase the transmission power of the transmitting end; if SIR > SIRtarget, transmit TPC order in order to reduce the transmission power of the transmitting end.

In this document, we call the TrCH that estimates BLERest the reference transport channel, denoted as TrCHref (reference transport channel), and the traffic transmitted on this TrCH is called reference traffic. It should be noted that, under the condition of logical channel multiplexing, multiple services may be transmitted on one TrCH, and at this time, we consider these services as an equivalent service; in addition, in the actual communication process, there is a dedicated signaling channel for carrying the signaling of the access stratum and the non-access stratum to serve the communication between users, and the signaling channel corresponds to a TrCH and also has a corresponding QoS requirement, where we consider the transmission service of the signaling to be an equivalent service.

Under the condition of multiple services, the rate matching process of the physical layer plays an important role in ensuring the QoS of each service. The rate matching is to match the number of bits to be transmitted with the number of bits available for a corresponding frame by using a bit repetition or puncturing method. The physical layer performs rate matching on each TrCH, whether bits on each TrCH are repeated or punctured is related to the number of available bits per frame of the physical layer and a corresponding Rate Matching Attribute (RMA) value, and a specific rate matching processing procedure is described in detail in 3GPP protocol 25.212. It is emphasized that the RMA for each TrCH is provided by higher layer protocols, and for each TrCH, the difference in the corresponding RMA may result in different repetition rates or puncturing rates when the TrCH is multiplexed into the same frame, i.e., corresponding rate matching Gain (Gain) _RM ) Different, and therefore different, impacts on communication quality, so in the case of multiple services, a higher layer needs to configure an appropriate RMA for each TrCH to ensure QoS of each service. Rate matching gain is defined herein as:

n of formula (1) _beforcRM Indicates the corresponding number of bits per frame, N, of the TrCH before rate matching _afterRM Indicating the corresponding number of bits per frame of the TrCH after rate matching.

A basic requirement of UMTS is that several services can be multiplexed onto one physical connection, and one physical connection corresponds to one ILPC, i.e. all services have only one target value SIRtarget of the ILPC. For the case of multiple services, how to guarantee the QoS of each service is currently different, and the following is briefly introduced:

1. the control is carried out according to only one service, the QoS corresponding to the service is ensured, the QoS of other services is determined by the corresponding RMA parameters configured by the upper layer, and the different parameters mean different rate matching gains. The disadvantages of this method are evident: if the corresponding RMA configured by the upper layer for different services is unreasonable, the QoS of other services cannot be ensured;

2. and simultaneously, carrying out power control according to all services, namely estimating the quality of each service, and increasing the SIRtarget as long as the quality of one service is lower than the target quality. The result of this method is that the actual quality of each service is higher than the target quality, which results in waste of power resources, and the method is not very relevant because of less users in the initial stage of system networking, but limits the capacity of the system as the number of users increases.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for improving the outer loop power control performance under the condition of multiple services, and the method ensures the QoS requirements of each service of a user by changing the rate matching attribute value corresponding to a transmission channel so as to reduce the waste of power resources and improve the system capacity.

In order to solve the above technical problem, the present invention provides a method for improving outer loop power control performance under multi-service condition, comprising the following steps:

step A: firstly, selecting a transmission channel as a reference transmission channel for outer loop power control;

and B, step B: performing outer loop power control on a reference transmission channel, and estimating the block error rate of the transmission channels of other transmission channels;

step C: judging whether the outer ring power control of the reference transmission channel is converged according to the quality estimation value of the reference transmission channel, and if so, judging whether the quality estimation of other transmission channels meets the corresponding quality target value;

step D: if the quality estimation of other transmission channels meets the corresponding quality target value, keeping the rate matching attribute value corresponding to each transmission channel unchanged; if the quality of one or more services in other transmission channels is better or deviated, the rate matching attribute value corresponding to the transmission channel is adjusted, the rate matching attribute value is increased for the transmission channel with the quality deviation, and the rate matching attribute value is reduced for the transmission channel with the better quality.

Compared with the first method mentioned above, the method of the present invention overcomes the dependence of method 1 on the initial RMA configuration, and can ensure that each service substantially meets the corresponding quality requirement by adjusting the RMA. Compared with the method 2, the method ensures that all TrCHs basically meet the quality target, reduces the power waste and improves the system capacity compared with the method 2 that the quality of each service is better.

Drawings

Fig. 1 is a flowchart illustrating a conventional outer loop power control method.

Fig. 2 is a diagram illustrating a relationship between an outer loop power control and an inner loop power control in the prior art.

Fig. 3 is a flow chart of the outer loop power control method of the present invention.

Fig. 4 is a flow chart of a conventional outer loop power control sawtooth algorithm.

Detailed Description

The following describes the specific processing flow of the present invention in detail, and the flow chart is shown in fig. 3.

Step 1: one transport channel is selected as the reference transport channel TrCHref of the OLPC. Here, the TrCH corresponding to the service with the highest priority is selected as the reference channel, and the priority of each service is set by the network side.

Step 2: a Timer is started. The calculation formula of the initial timing length TimerLenght is as follows:

TimerLength＝MAX{TimerLength _i }

wherein i =1, 2., N is the total number of transport channels, OLPCPeriodi is the power control period corresponding to the ith transport channel, BLERtargeti is the quality target value corresponding to the ith transport channel, and TTIi and maxtbpertti are the transmission time interval of the ith transport channel and the maximum number of transport blocks transmitted in a TTI, respectively. The timing length at which the timer restarts is described below.

And step 3: OLPC is performed on TrCHref, and bit error rate estimates are estimated for other TrCHs. Here, the OLPC algorithm employs a typical sawtooth (sawtooth) algorithm, as shown in fig. 4: the algorithm comprises the steps of firstly starting a period timer, wherein the time length of the timer is the period of OLPC, estimating an error rate estimation value in the OLPC period, then comparing the error rate estimation value with a block error rate target value after the timer is overtime, and determining whether to reduce or increase a signal-to-interference ratio target value of inner-loop power control according to a comparison result, wherein StepSize is the adjusting step length of the outer-loop power control. For each transport channel, a corresponding error rate estimate is calculated and stored, denoted BLEResti. After each power control adjustment, the next step is carried out.

And 4, step 4: and judging whether the Timer is overtime or not. If not, entering step 3; if time out, go to step 5.

And 5: judging whether OLPC is converged, if not, entering step 2, and setting the timing length to be equal to the initial timing length; if so, go to step 6. Here, OLPC convergence is defined as the estimated quality of TrCHref, blerrest, falling within the range BLERtarget-Threshold1, BLERtarget + the short 2, where BLERtarget refers to the target value of the quality corresponding to TrCHref, and Threshold1 and Threshold2 both take on 30% of BLERtarget.

And 6: judging the quality of other TrCHs, and if the quality of any other TrCH meets the following conditions:

BLER _esti ∈[BLER _targeti -Threshold1 _i ，BLER _targeti +Threshold2 _i ](3)

wherein Threshold1 _i ＝Threshold2 _i ＝BLER _targeti X 30%, indicating that the quality of other transmission channels meets or is superior to the corresponding quality target, at this time, the rate matching attribute value does not need to be adjusted, and the step 2 is entered, wherein the timing LENGTH is set to be 2 times of the original timing LENGTH, but the longest timing LENGTH does not exceed MAX _ TIMER _ LENGTH, and MAX _ TIMER _ LENGTH =5s; otherwise, it indicates that there is a quality deviation or a quality deviation of one or more trchs, and at this time, the rate matching attribute value of the transport channel needs to be adjusted, and step 7 is entered.

And 7: determining the number of transport channels with quality deviation and preferred transport channels, we consider all those satisfying BLER _esti ＞BLER _targeti +Threshold2 _i Is a transmission channel with quality deviation, assuming N _worseAll satisfy BLER _esti ＜BLER _targeti -Threshold1 _i Is a quality-preferred transmission channel, assuming N _better And (4) respectively. If N is present _worse If the value is more than 0, entering a step 8; otherwise, go to step 9. Parameter Threshold1 in this step _i ，Threshold2 _i The values of (2) are the same as those in step (6).

And 8: to N _worse The corresponding rate matching attribute RMA values are respectively adjusted upwards by the transmission channels, and thenAnd (5) entering a step 2, and setting the timer timing length as the initial timing length.

The RMA adjustment algorithm is as follows: the rate matching Gain before RMA adjustment is calculated according to the rate matching Gain defined by equation (1) and the rate matching calculation procedure specified in protocol 25.212 _{RM_old} Then, the RMA adjusted rate matching Gain is determined _{RM_new} According to Gain _{RM_new} A new RMA value is calculated. Gain _{RM_new} The calculation formula is as follows:

gain in equation (4) _StepUP The values of (a) are divided into two cases: for convolutional coded TrCH, the parameter takes the value 0.1dB; for Turbo coded TrCH, the parameter takes 0.05dB. MaxGain _StepUP The value of (2) is also divided into two cases, and for the convolution coded TrCH, the parameter takes 0.5dB; for Turbo coded TrCH, the parameter takes 0.3dB.

The RMA adjusting process comprises the following steps: for the uplink OLPC, a network terminal firstly initiates a radio link synchronization reconfiguration process to inform a base station to change RMA, then initiates a transmission channel reconfiguration process to inform a mobile terminal to change RMA; for downlink OLPC, the mobile terminal firstly initiates an RMA modification request to the network end through an air interface signaling, and the network end then initiates a radio link synchronization reconfiguration process and notifies the UE to reconfigure a transmission channel. For example, for a 3GPP WCDMA system, the radio link synchronization reconfiguration may employ a signaling procedure specified by the protocol 25.331.

And step 9: to N _better And (3) respectively downwards adjusting the corresponding rate matching attribute RMA values by the transmission channels, and then entering the step 2, and setting the timer timing length as the initial timing length.

The RMA adjustment algorithm is as follows: rate matching defined according to equation (1)The rate matching Gain before RMA adjustment is calculated using the rate matching calculation procedure specified in protocol 25.212 _{RM_old} Then, the RMA adjusted rate matching Gain is determined _{RM_new} According to Gain _{RM_new} New RMA values were calculated. Gain _{RM_new} The calculation formula is as follows:

(5)

gain in equation (5) _StepDown The values of (a) are divided into two cases: for convolution coded TrCH, the parameter takes 0.05dB; for Turbo coded transmission channels, the parameter takes on the value 0.03dB. MaxGain _StepDown The value of (2) is also divided into two cases, and for the convolution coded TrCH, the parameter takes 0.4dB; for Turbo coded TrCH, the parameter takes on the value of 0.2dB.

RMA adjustment process is the same as step 8.

Of course, the invention is not limited to the above-described embodiments, and variations known to those skilled in the art are within the scope of the invention, such as:

there are various selection criteria for the initial reference TrCH in step 1, and in addition to the above-mentioned selection criteria, there is also a direct selection of the TrCH corresponding to the signaling or Circuit Switching (CS) domain voice service as TrCHref.

Other methods can be selected for setting the timing length of the timer in steps 2, 5, 6, and 7, for example, the initial timing length is directly set as the power control period of the OLPC or an integral multiple of the power control period, and the timing length when the timer is restarted can be set to be the same as the initial timing length, or a fixed value can be added each time.

The decision criterion of the OLPC algorithm in step 3 may also be an estimated value of the Bit Error Rate (BER) of the physical channel or information such as the received signal-to-noise ratio (Eb/No). The adjustment period of the OLPC may be one TTI or an integer multiple of the TTI. The adjustment step size of SIRtar by OLPC can also be flexibly set.

In step 5, the sizes of Threshold1 and the size of the Threshold2 in the OLPC convergence are determined to be flexibly set, and the sizes may not be equal.

The threshold di in step 6 may be set to other values, such as BLERtargeti × 20%, BLERtargeti × 10%, or the like.

The MAX _ TIMER _ LENGTH in step 6 may be set to other values, such as 3s or 10s, etc.

Threshold1 in step 7 _i ，Threshold2 _i The values of (a) may be equal or unequal, and the other two values may also be other values.

Parameter Gain in RMA adjusting algorithm in step 8 _StepUP 、MaxGain _StepUP The value can be flexibly set, and in addition, the RMA adjusting algorithm can be other algorithms.

Parameter Gain in RMA adjusting algorithm in step 9 _StepDown 、MaxGain _StepDown The value can be flexibly set, and in addition, the RMA adjusting algorithm can be other algorithms.

Claims

1. A method for improving outer loop power control performance under multi-service condition is characterized by comprising the following steps:

and B: performing outer loop power control on a reference transmission channel, and estimating the block error rate of other transmission channels;

and C: judging whether the outer ring power control of the reference transmission channel is converged according to the quality estimation value of the reference transmission channel, and if so, judging whether the quality estimation of other transmission channels meets the corresponding quality target value;

step D: if the quality estimation of other transmission channels meets the corresponding quality target value, keeping the rate matching attribute value corresponding to each transmission channel unchanged; if the quality of one or more services in other transmission channels is preferred or deviated, the rate matching attribute value corresponding to the transmission channel is adjusted, the rate matching attribute value is increased for the transmission channel with the quality deviation, and the rate matching attribute value is reduced for the transmission channel with the preferred quality.

2. The method of claim 1, wherein a timer is started between step a and step B, and the timer is set with an initial timing length.

3. The method for improving outer loop power control performance under multi-service condition according to claim 2, characterized in that, a step of determining whether the timer is overtime is further included between step B and step C, if yes, step C is executed, otherwise, step B is executed.

4. The method of claim 3, wherein the step C further comprises: and when the outer loop power control of the reference transmission channel does not converge, returning to the step of starting the timer, wherein the timing length of the timer is set to be equal to the initial timing length.

5. The method of claim 4, wherein in step D, if the quality of other transmission channels satisfies the corresponding quality target value, the step of starting the timer is executed again, and the timing length is set to be 2 times of the original timing length.

6. The method of claim 5, wherein the step of starting the timer is performed after adjusting the value of the rate matching attribute in step D, and at this time, the timing length of the timer is set as the initial timing length.

7. The method of claim 1, wherein the reference transport channel is a transport channel corresponding to a service with a highest priority.

8. The method of claim 1, wherein the reference transport channel is a transport channel corresponding to signaling or circuit switched domain voice service.

9. The method of claim 2, wherein the initial timing length of the timer is:

TimerLength＝MAX{TimerLength _i }

wherein i =1, 2., N is the total number of transport channels, OLPCPeriodi is the power control period corresponding to the ith transport channel, BLERtargeti is the quality target value corresponding to the ith transport channel, and TTIi and maxtbpertti are the transmission time interval of the ith transport channel and the maximum number of transport blocks transmitted in the transmission time interval, respectively.

10. The method of claim 2, wherein the initial timing length of the timer is the power control period of the outer loop power control or an integer multiple of the power control period.

11. The method of claim 1, wherein the outer-loop power control for the reference transport channel in step B employs a sawtooth algorithm, comprising the following steps: firstly, a period timer is started, the time length of the timer is the period of outer loop power control, an error rate estimation value is estimated in the outer loop power control period, then the error rate estimation value is compared with a block error rate target value after the timer is overtime, and whether the signal-to-interference ratio target value of inner loop power control is reduced or increased is determined according to the comparison result.

12. The method of claim 1, wherein the decision of the method for performing outer loop power control on the reference transport channel in step B is based on the estimated value of the bit error rate of the physical channel or the received snr information.

13. The method of claim 1, wherein the step C of determining whether the outer loop power control of the reference transport channel converges comprises: it is determined whether the quality estimate of the reference transport channel falls within the range BLERtarget-Threshold1, BLERtarget + the short 2, where BLERtarget refers to a quality target value corresponding to the reference transport channel.

14. The method of claim 13, wherein the Threshold1 and Threshold2 are both 10% to 30% of BLERtarget.

15. The method of improving outer loop power control performance in a multi-service environment as claimed in claim 14, wherein the Threshold1 and Threshold2 are different.

16. The method of claim 1, wherein the step C of determining whether the quality estimation of other transmission channels satisfies the corresponding quality target value comprises the steps of: judging whether other transmission channels meet the following conditions:

wherein Threshold1 _i ＝Threshold2 _i ＝BLER _targeti ×30％。

17. The method of claim 1 wherein the quality-biased transport channel in step D is the transport channel that satisfies BLER _csti ＞BLER _targcti +Threshold2 _i The transmission channel with better quality is to satisfy BLER _csti ＜BLER _targcti -Threshold1 _i 。

18. The method of claim 1, wherein the method for increasing the rate matching attribute value in step D comprises: calculating the Rate matching Gain before adjustment _{RM_old} Then determining the rate matching Gain after the rate matching attribute value is adjusted _{RM_new} According to Gain _{RM_new} Calculating new rate matching attribute value, said rate matching Gain _{RM_new} The calculation formula is as follows:

in the formula of Gain _StepUP The values of (a) are divided into two cases: for a convolutional coded transmission channel, the parameter takes the value of 0.1dB; for Turbo coded transmission channels, the parameter takes on the value 0.05dB _StepUP The value of (2) is also divided into two cases, and for the transmission channel of the convolutional coding, the parameter takes a value of 0.5dB; for a Turbo coded transmission channel, the parameter takes on the value of 0.3dB.

19. The method of claim 1, wherein the method of reducing the rate matching attribute value in step D comprises: calculating a rate matching Gain before adjustment of the rate matching attribute value _{RM_old} Then, the rate matching Gain adjusted by the rate matching attribute value is determined _{RM_new} According to Gain _{RM_new} Computing a new value of the rate matching attribute, gain _{RM_new} The calculation formula is as follows:

in the formula Gain _StepDown The values of (a) are divided into two cases: for a transmission channel of convolutional coding, the parameter takes the value of 0.05dB; for Turbo coded transmission channels, the parameter takes on the value 0.03db _StepDown The value of the parameter is also divided into two cases, and the value of the parameter is 0.4dB for a transmission channel of convolutional coding; for the Turbo encoded transmission channel, the parameter takes on the value of 0.2dB.

20. The method of claim 18 or 19, wherein the adjusting the value of the rate matching attribute comprises: for uplink OLPC, the network end firstly initiates a wireless link synchronization reconfiguration process to inform the base station to change the rate matching attribute value, then initiates a transmission channel reconfiguration process to inform the mobile terminal to change the rate matching attribute value; for the downlink OLPC, the mobile terminal firstly initiates a rate matching attribute value modification request to the network terminal through an air interface signaling, and the network terminal then initiates a radio link synchronization reconfiguration process and notifies the UE to reconfigure a transmission channel.