CN101083493B - Method of closed loop power control adaptive control of CDMA system - Google Patents

Method of closed loop power control adaptive control of CDMA system Download PDF

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CN101083493B
CN101083493B CN2007100741009A CN200710074100A CN101083493B CN 101083493 B CN101083493 B CN 101083493B CN 2007100741009 A CN2007100741009 A CN 2007100741009A CN 200710074100 A CN200710074100 A CN 200710074100A CN 101083493 B CN101083493 B CN 101083493B
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power control
closed
loop power
command word
control command
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CN101083493A (en
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耿鹏
江海
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ZTE Corp
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ZTE Corp
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Abstract

The invention publishes a method of code division multiple closed-loop system, which includes the following steps: 1) measure failure probability of through power control order character compensation demodulation in real-time; 2) set a failure probability threshold value, when the failure probability state in step 1) is bigger than the threshold value, turn off the closed loop control; Otherwise, turn on the closed loop control. From the characteristic whether power control order character compensate the SIR or not, count the failure probability of power control order character in certain time, to judge whether the closed loop control should turn on or not, so can avoid the difficulty when estimate the UE velocity. In addition, also provide a decision mechanism for quick recovery of the closed loop control, to enhance restore ability when suffering sudden depravation.

Description

A kind of code division multiple access system closed-loop power control Method of Adaptive Control
Technical field
The present invention relates to code division multiple access system, relate in particular to the Method of Adaptive Control of a kind of closed power control in synchronous time division code division multiple access (TD-SCDMA) system.
Background technology
Power control is an important technology of cdma system.Because the cdma system that 3G adopts all is the identical networking mode, therefore can control the interference and the load of whole network by power controlling, power control can also solve near-far interference in addition, a series of advantages such as asthenia.
The method of closed-loop control, the close-loop power controlling method unanimity of up-downgoing are all adopted in power control in the existing C DMA system usually for Dedicated Traffic Channel.Be controlled to be example with up closed power, system side (Node B) produces power control command word (TPC) according to the special uplink channel information that has received by certain strategy, and be handed down to terminal (UE) in the relevant position of downlink dedicated channels, be used to adjust the transmitting power of follow-up UE special uplink channel, thereby form closed-loop control.Wherein the system side strategy that produces the TPC command word normally compares the symbol signal interference ratio of measuring (SIR) with the high-rise target signal interference ratio of setting, and greatly then TPC be " a reduction power ", little or etc. then TPC be " raising power ", this is that interior ring is controlled; And the high-rise target signal interference ratio that is provided with also is a closed loop adjustment, mainly adjusts according to the demodulation bit error rate performance, and this is outer shroud control.
Closed power control can be played compensating action to a certain extent for wireless channel is fast weak, has suppressed the fluctuation of demodulation symbol signal interference ratio, has improved the demodulation performance of wireless receiver.But, (for example WCDMA is 1500Hz to be subject to the frequency of power control, TD-SCDMA is 200Hz) and the hysteresis effect of closed-loop control, closed-loop power control progressively reduces along with the increase of UE movement velocity the effect of fast weak compensation, more than UE speed height arrives to a certain degree, produce TPC control word channel quality constantly and equipment according to the channel quality correlation in the actual moment of adjusting power of this control word very weak the time, existing closed power control not only can not compensate the fast weak demodulation symbol signal interference ratio fluctuation that brings, cause the more great fluctuation process of demodulation symbol signal interference ratio on the contrary owing to artificial adjustment power at random, thereby reduce the performance of wireless receiver demodulation.
Summary of the invention
For defective and the deficiency that overcomes prior art, the present invention proposes a kind of code division multiple access system closed-loop power control Method of Adaptive Control, whether can to compensate the current wireless channel weak soon by the closed-loop power control of judging that certain strategy is real-time, shield or open closed-loop power control then, under UE low-speed motion environment, open closed-loop power control, thereby obtain the power control gain; And under UE high-speed motion environment, shield closed-loop power control, keep demodulation performance not worsen.
The code division multiple access system closed-loop power control Method of Adaptive Control that the present invention proposes comprises following treatment step:
1) measures the failure probability that compensates the demodulation symbol signal interference ratio by power control command word in real time;
2) set a failure probability threshold value, when the failure probability in the step 1) during greater than described threshold value, the shielding closed-loop power control; Otherwise unlatching closed-loop power control.
Preferably, described step 1) specifically comprises following processing procedure:
1.1) compensation process of power control command word is done validity check, if make the demodulation symbol signal interference ratio approach desired value, then be judged as effectively in the moment that this command word comes into force, otherwise be judged as invalid;
1.2) obtain the failure probability of power control command word according to the validity judge result of a plurality of power control command words in the statistic window of certain-length.
Preferably, judge whether the demodulation symbol signal interference ratio approaches desired value and be specially by judging whether to satisfy following equation realization in described step 1.1):
sign(SIR(n+1)-TPC(n)-SIR tgt)＝-TPC(n)
Wherein TPC (n) is a n power control command word constantly, TPC (n) value+1 or-1, and+1 for raising power, and-1 for reducing power; SIR TgtBe power control symbol signal interference ratio sir target value; The symbol signal interference ratio SIR that SIR (n+1) expression n+1 actual measurement is constantly arrived; Symbol sign (.) expression is got positive negative direction to the number in the bracket, promptly more than or equal to 0 be+1, less than 0 be-1.
Preferably, the power control command word realization of raising power and reducing power is alternately launched in the employing of shielding closed-loop power control described step 2).
Preferably, during the shielding closed-loop power control, also comprise following treatment step: produce power control command word according to existing closed-loop power control, and will produce change step 2 after power control command word is measured its failure probability according to step 1)) carry out next closed-loop power control judgement of opening or shielding constantly.
Preferably, during the shielding closed-loop power control, also comprise following treatment step: if produced continuous equidirectional power control command word according to closed-loop power control method, and its number surpasses the threshold value of setting, then open the closed-loop power control state, and issue the power control command word that adopts existing closed-loop power control method to produce.
The present invention starts with from the characteristic whether power control command word that existing closed-loop power control method is generated really compensates the instantaneous SIR fluctuation of demodulation symbol, and add up the failure probability of power control command word within a certain period of time, thereby whether the real-time closed-loop power control method of judging should be opened or be shielded, and then has avoided the difficulty of directly the UE movement velocity being estimated.
In addition, a decision mechanism that helps fast quick-recovery power control opening also is provided, maintenance is carried out power control command word failure probability statistics and the shielding of closed-loop power control state or is opened judgement according to the window long period when, the closed-loop power control recovery capability when the raising environment worsens suddenly.
Description of drawings
Fig. 1 is a code division multiple access system closed-loop power control Method of Adaptive Control flow chart of the present invention;
The flow chart of Fig. 2 for adopting Method of Adaptive Control of the present invention in TD-CDMA system uplink closed power, to use.
Embodiment
Because thinking to judge accurately user's translational speed is a very challenging thing,, movement velocity causes unnecessary power control to close to worsen link performance more because judging to make mistakes.Therefore, the present invention starts with from the characteristic whether power control command word that existing closed-loop power control method is generated really compensates the instantaneous SIR fluctuation of demodulation symbol, and add up the failure probability of power control command word within a certain period of time, thereby whether the real-time closed-loop power control method of judging should be opened or be closed, and then has avoided the difficulty of directly the UE movement velocity being estimated.Method of Adaptive Control of the present invention as shown in Figure 1 may further comprise the steps:
1. the power control command word that the existing closed-loop power control method of arbitrary basis is produced is done validity check, if it makes the demodulation symbol signal interference ratio more approach desired value really in moment that this command word comes into force, then be judged as effectively, otherwise be judged as invalid;
2. calculate the failure probability of current time power control command word according to the validity judge result of a plurality of power control command words in the statistic window of certain-length;
3. if above-mentioned power control command word failure probability surpasses certain thresholding, then the transmitting order to lower levels word adopts alternately emission of " raising "/" reduction ", the i.e. effect of " shielding " closed-loop power control; Otherwise the command word that the transmitting order to lower levels word adopts existing closed-loop power control method to produce, i.e. the effect of " unlatching " closed-loop power control;
4. during above-mentioned closed-loop power control effect shielding, still need produce power control command word according to existing closed-loop power control method, and according to the method statistic power control command word failure probability of step 1 step 2, the judgement that statistics is carried out the closed-loop power control shielding or opened according to step 3;
5. during above-mentioned closed-loop power control effect shielding, surpass certain thresholding if produced the number of continuous equidirectional power control command word according to existing closed-loop power control method, then recover closed-loop power control " unlatching " state, promptly the transmitting order to lower levels word adopts the power control command word that existing closed-loop power control method produces.
Wherein, whether the validity check of the power control command word TPC (n) that produces according to existing closed-loop power control method of the arbitrary moment n in the step 1 can satisfy with following equation (1) and judge:
sign(SIR(n+1)-TPC(n)-SIR tgt)＝-TPC(n) (1)
Wherein TPC (n) has only two values, and power is raised in "+1 " expression, and " 1 " expression reduces power; SIR TgtExpression power control sir target value; The SIR that SIR (n+1) expression n+1 (being controlled terminal is adjusted transmitting power according to TPC (n) the moment) actual measurement is constantly arrived; Symbol sign (.) expression is got positive negative direction to the number in the bracket, promptly more than or equal to 0 be "+1 ", less than 0 be " 1 ".
In addition, step 5 provides a decision mechanism that helps fast quick-recovery power control opening, is keeping above-mentioned closed-loop power control recovery capability when improving environment when carrying out power control command word failure probability statistics and the judgement of closed-loop power control status switch according to the window long period as far as possible and worsening suddenly.
Uplink closed-loop power control with the TD-SCDMA system is an example below, and 2 pairs of the specific embodiment of the present invention are described in further detail in conjunction with the accompanying drawings.Thought of the present invention is not limited only to the uplink closed loop of TD-SCDMA system.
At first define some parameters that this method relates to:
FPC (k u)-virtual power control on off state, 1-〉power control opens 0-〉power control closes; (being initialized as 1)
Figure G07174100920070530D000052
TpcErrCnt (k uInvalid TPC counter in the)-window; (being initialized as 0)
TpcCnt (k uTotal TPC counter in the)-window; (being initialized as 0)
Figure G07174100920070530D000054
The statistic window of TpcWin-TPC failure probability is long, is unit with the subframe; (span 10-1000 subframe)
OldTpc (k uThe TPC equivalent command word of)-issue recently ,+1-〉power per liter ,-1-〉power falls; (being initially 0)
Figure G07174100920070530D000056
OldTpc2 (k uThe TPC command word that the existing power control algorithm of the basis of)-nearest produces ,+1-〉power per liter ,-1-〉power falls; (being initialized as 0)
Figure G07174100920070530D000057
SIR Tgt(k u)-power control sir target value; (by high-rise exterior ring power control decision)
Figure G07174100920070530D000058
TpcErrRatio-power control command word failure probability thresholding; (span 0.2-0.5)
Figure G07174100920070530D000059
TpcMonoCnt (k u)-in the same way adds up the TPC counter; (being initialized as 1)
Figure G07174100920070530D0000510
ThreMonoTpc-in the same way adds up the TPC thresholding; (span 2-20)
At arbitrary subframe n, user k uProcessing procedure as follows:
The first step: if the instantaneous demodulation symbol signal to noise ratio SIR (k of input u, be not empty n), then with counter TpcCnt (k u) add 1, forwarded for second step to; Otherwise forwarded for the 3rd step to;
Second step: judge equation " sign[SIR (k u, n)-OldTpc (k u)-SIR Tgt(k u)] OldTpc2 (k u)=1 " if set up? set up just with counter TpcErrCnt (k u) add 1; Forwarded for the 3rd step to;
The 3rd step: judge that current subframe is the integral multiple of the long TpcWin of TPC failure probability statistic window? be then to forward for the 4th step to; Otherwise forwarded for the 6th step to;
The 4th step: the judgement inequality " TpcErrCnt ( k u ) TpcCnt ( k u ) ≤ TpcErrRatio " set up? be then to make fPC (k u)=1; Otherwise make fPC (k u)=0; Forwarded for the 5th step to;
The 5th step: counter TpcErrCnt (k u) and TpcCnt (k u) zero clearing;
The 6th step:, forwarded for the 7th step to if current subframe has descending TPC to issue; Otherwise forwarded for the 12 step to;
The 7th step: according to having the TPC command word that the closed-loop power control algorithm produces the n subframe now, if this command word and OldTpc2 (k u) identical then with counter TpcMonoCnt (k u) add 1, forwarded for the 8th step to; Otherwise with counter TpcMonoCnt (k u) put 1, forwarded for the 9th step to;
The 8th step: judge counter TpcMonoCnt (k u) whether surpass thresholding ThreMonoTpc, be then to make fPC (k u)=1 is simultaneously with counter TpcMonoCnt (k u) put 1; Otherwise keep fPC (k u) and TpcMonoCnt (k u) constant; Forwarded for the 9th step to;
The 9th step: the TPC command word that the 7th step was produced deposits OldTpc2 (k in u), forwarded for the tenth step to;
The tenth step: if power control opening fPC is (k uSet up)=1, then makes OldTpc (k u)=OldTpc2 (k u); Otherwise make OldTpc (k uOldTpc (the k of)=- u); Forwarded for the 11 step to;
The 11 step: determine the power control command word TPC (k that current subframe issues u, n) be OldTpc (k u), and carry out the mapping of TPC sign bit, i.e. "+1 "-" 11 ", " 1 "-" 00 ";
The 12 step: finish.

Claims (3)

1. code division multiple access system closed-loop power control Method of Adaptive Control is characterized in that described method comprises following treatment step:
1) measures the failure probability that compensates the demodulation symbol signal interference ratio by power control command word in real time;
2) set a failure probability threshold value, when the failure probability in the step 1) during greater than described threshold value, by the transmitting order to lower levels word adopt raise power and reduce power alternately emission with the shielding closed-loop power control; Otherwise issue the power control command word that produces by existing closed-loop power control method to open closed-loop power control;
Described step 1) specifically comprises following processing procedure:
1.1) compensation process of power control command word is done validity check, if make the demodulation symbol signal interference ratio approach desired value, then be judged as effectively in the moment that this command word comes into force, otherwise be judged as invalid;
1.2) obtain the failure probability of power control command word according to the validity judge result of a plurality of power control command words in the statistic window of certain-length;
Described step 1.1) judge whether the demodulation symbol signal interference ratio approaches desired value and be specially that following equation realizes by judging whether to satisfy, and wherein, satisfies following equation judgement demodulation symbol signal interference ratio and approaches desired value in:
sign(SIR(n+1)-TPC(n)-SIR tgt)＝-TPC(n)
Wherein TPC (n) is a n power control command word constantly, TPC (n) value+1 or-1, and+1 for raising power, and-1 for reducing power; SIR TgtBe power control demodulation symbol signal interference ratio desired value; The demodulation symbol signal interference ratio that SIR (n+1) expression n+1 actual measurement is constantly arrived; Symbol sign (.) expression is got positive negative direction to the number in the bracket, promptly more than or equal to 0 be+1, less than 0 be-1.
2. code division multiple access system closed-loop power control Method of Adaptive Control according to claim 1, it is characterized in that, during the shielding closed-loop power control, also comprise following treatment step: produce power control command word according to existing closed-loop power control, and will produce change step 2 after power control command word is measured its failure probability according to step 1)) carry out next closed-loop power control judgement of opening or shielding constantly.
3. code division multiple access system closed-loop power control Method of Adaptive Control according to claim 2, it is characterized in that, during the shielding closed-loop power control, also comprise following treatment step: if produced continuous equidirectional power control command word according to existing closed-loop power control method, and its number surpasses the threshold value of setting, then open the closed-loop power control state, and issue the power control command word that adopts existing closed-loop power control method to produce.
CN2007100741009A 2007-04-24 2007-04-24 Method of closed loop power control adaptive control of CDMA system Expired - Fee Related CN101083493B (en)

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Publication number Priority date Publication date Assignee Title
CN1359566A (en) * 1999-06-30 2002-07-17 高通股份有限公司 SIR threshold in a closed loop power control system
CN1491048A (en) * 2002-10-18 2004-04-21 华为技术有限公司 Closed-loop power controlling method in radio communication system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1359566A (en) * 1999-06-30 2002-07-17 高通股份有限公司 SIR threshold in a closed loop power control system
CN1491048A (en) * 2002-10-18 2004-04-21 华为技术有限公司 Closed-loop power controlling method in radio communication system

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