CN1434593A - Method for controlling external loop power in WCDMA system - Google Patents

Abstract

This invention provides an external loop power control method in WCDMA overcoming the shortage of not considering the needed special process at signal DTX in ordinary outer ring power control to set up a unified output ring power control at non DTX and DTX to follow the environ-menrel change on real-time. This method determines the target signal-to-interference ratio based on actual need to increase systematic capacit-ance at the maximum under the condition of guaranteeing communication quality.

Description

The method of exterior ring power control in the WCDMA system

Technical field

The present invention relates to power control techniques among the WCDMA, relate in particular to the method for exterior ring power control.

Background technology

Common WCDMA power control techniques can be divided into open Loop Power control and closed power control.The basic functional principle of open Loop Power control is to be the principle of constant according to the long-pending of user's received power and transmitting power, measures the size of received power in advance, and determines the size of transmitting power thus.Open Loop Power control is used for determining user's Initial Trans, or the transmission power adjustment the during sudden change of user's received power, is used for overcoming shade and path loss.But open Loop Power control reckons without the asymmetry of uplink and downlink channel electric wave power, thereby its accuracy is difficult to be guaranteed.Closed power control is head it off well, closed power control is used to overcome the decline that Doppler frequency produces, it is to have identical power when making each mobile station signal reach the base station that the number of mobile stations (power system capacity) that can call out emission simultaneously reaches the desired condition of maximum, and should be in that to satisfy under the prerequisite of link performance signal power as far as possible little.By the measurement estimation of signal interference ratio (SIR) and the contrast of signal interference ratio desired value (SIRtarget), determine power control bit information, by channel power control bit information is sent to transmitting terminal then, and regulate the size of transmitting power according to this, this desired value is exactly the correct required signal interference ratio of demodulation useful signal.Yet under different multi-path environments, this value is different, therefore needs the mechanism of an exterior ring power control (OLPC:Outer Loop Power Control).Exterior ring power control is the quality according to communication, normally the Block Error Rate of received signal (BLER:Block Error Rate), the error rate (BER:Bit Error Rate) and frame error rate (FER:Fame Error Rate) are adjusted the desired value of inner loop power control, make system can satisfy the requirement of communication quality all the time with minimal power.

Power control basic framework as shown in Figure 1 in the WCDMA system, at UTRAN end (UMTS Terrestrial radio access network), power control section branch between base station (NodeB) 2 and the radio network controller (RNC) 3 is named exterior ring power control, and the power control section branch between base station (NodeB) 2 and the travelling carriage (UE) 1 is named inner loop power control.Because one the link final mass is that Block Error Rate/frame error rate/error rate (BLER/FER/BER) by this link is determined, the thinking of exterior ring power control is exactly the BLER/FER/BER of monitoring link, make the BLER/FER/BER of this link approach its desired value, final purpose is the quality of reception that guarantees link.As the BLER/FER/BER that measures is lower than its desired value, then reduces the SIRtarget value of inner loop power; As the BLER/BER/FER that measures is higher than its desired value, then improves the SIRtarget value of inner loop power.The basic framework of exterior ring power control as shown in Figure 2 in the WCDMA system, according to the needs that satisfy service feature, set the desired value of BLER/FER/BER, utilize the measured value of BLER/FER/BER again, determine the size of an exterior ring power control adjustment cycle internal object signal interference ratio.Inner loop power control is according to the relation of this target signal interference ratio and measurement signal interference ratio, and determining to increase still is the reduction transmitting power.

Only considered generally that in existing technology signal launches (non-DTX) situation continuously, and do not considered the exterior ring power control under the discontinuous emission of signal (DTX situation).But for communication system, the situation of discontinuous emission (DTX) exists widely.For example, for speech business, there is not the time of speaking; For data service, always online situation etc.Because the BLER/FER/BER that Dedicated Physical Control Channel (DPDCH) is corresponding is the embodiment of final communication quality, so carry out exterior ring power control based on the BLER/FER/BER of DPDCH correspondence usually.Yet during DTX, for speech business, the target signal interference ratio will reduce, and when the signal interference ratio of Dedicated Physical Data Channel (DPCCH) is lower than synchronous threshold requirement, can cause call drop; DTX influences the recovery of communication performance after finishing.Same, after the value of target signal interference ratio reduces,, set up Radio Link and connect and will have any problem for soft handover.When new sub-district path loss surpasses the path loss of current service cell, the signal quality at place, new base station is poor, cause producing almost can't receive synchronous to the up channel at base station transceiver place, therefore, high path loss handoff candidate base station and travelling carriage are had any problem synchronously, and this has also increased the chance of call drop.For data service, though can not reduce the target signal interference ratio during the DTX, because the variation of environmental condition, DTX finishes the back communication performance and fails in time to recover, and communication performance may worsen for some time.Do not cause communication quality to descend owing to set up exterior ring power control common under non-DTX and the DTX situation in the prior art.

Summary of the invention

The objective of the invention is to consider the characteristics of DTX, set up exterior ring power control framework unified under non-DTX and the DTX situation, come better tracking environmental to change, guarantee communication quality, improve power system capacity.

The object of the present invention is achieved like this, launch continuously at signal and set up unified exterior ring power control under (non-DTX) and two kinds of situations of the discontinuous emission of signal (DTX), setting parameter N is a number of adjusting the required Transmission Time Interval of target signal interference ratio (SIR) (TTI) in the exterior ring power control, parameter N 1 is launched the number of the Transmission Time Interval (TTI) during (non-DTX) continuously for signal, parameter N 2 is the number of the Transmission Time Interval (TTI) during the discontinuous emission of signal (DTX), satisfy N1+N2=N simultaneously, system provides the adjustment cycle T of exterior ring power control, described adjustment cycle rounds after divided by described Transmission Time Interval (TTI) and obtains N, the MAC layer is added up the transmission situation in N the described Transmission Time Interval (TTI), and N1 and N2 are counted respectively according to N, N back zero clearing of every meter has following three kinds of situations like this:

(a) when N1 ≠ 0, N2=0, then respective signal is launched (non-DTX) situation continuously, and system is according to carry out exterior ring power control based on three kinds of methods of Block Error Rate/frame error rate/error rate (BLER/FER/BER) of DPDCH correspondence.

As carry out exterior ring power control according to Block Error Rate (BLER), then determine the size of target signal interference ratio (SIR), promptly according to the difference of measuring Block Error Rate (BLER) and target Block Error Rate (BLERtarget) based on the DPDCH correspondence $\mathrm{SIRt}\arg \mathrm{et}(n+1)=\mathrm{SIRt}\arg \mathrm{et}\left(n\right)+(1-r)(\frac{\mathrm{BLER}}{\mathrm{BLERt}\arg \mathrm{et}}-1)\mathrm{SP}$

Step factor SP is the real number greater than zero, introduces in variable step and adjusts factor r, and r is smaller or equal to 1 real number more than or equal to zero.If use when carrying out exterior ring power control based on the error rate (BER) and frame error rate (FER), the BLER in the above-mentioned formula substitutes with BER and FER and gets final product.

(b) when N1 ≠ 0, N2 ≠ 0, then discontinuous emission of respective signal (DTX) and signal are launched (non-DTX) mixing situation continuously, and system does not carry out exterior ring power control;

(c) work as N1=0, N2 ≠ 0, the discontinuous emission of respective signal (DTX) situation then, system be according to carrying out exterior ring power control based on the error rate (BER) of DPCCH correspondence, two kinds of situations when being divided into non-soft handover and during soft handover.

If when being non-soft handover, then carry out carrying out exterior ring power control based on the BER of DPCCH correspondence.The method that its desired value is chosen is: before the DTX, system can obtain the error rate (BER) of the DPCCH under the normal exterior ring power control, be the mean value in the exterior ring power control adjustment cycle, then the desired value BERtarget of this numerical value as the error rate (BER), that is to say the BER when the nearest non-DTX of DTX, but under the situation that can't obtain, can only use representative value, such as being the BER that obtains under the situation of DTX at the very start.If the BER that reports in the Frame is respectively BER1, BER2 ..., BERN, BERm=(BER1+ averages ... + BERN)/N, then

As BERm＞BERtarget+BERtarget1, target signal interference ratio (SIR) is improved Db;

When BERm＜BERtarget-BERtarget2, target signal interference ratio (SIR) is reduced

Db;

Target signal interference ratio (SIR) remains unchanged under other situation, The step-length that db controls less than inner loop power,

Db and BERtarget1, BERtarget2 all are parameters of being determined by emulation.

When soft handover, then carry out carrying out exterior ring power control based on the error rate (BER) of DPCCH correspondence equally, choosing desired value minimum in each bar link is the desired value of system.Report as multilink under the situation of the error rate (BER) of DPCCH, can handle and judge this link target signal interference ratio (SIR) that whether raises earlier respectively to each bar link, utilize result to judge again, when all links all require to raise target signal interference ratio (SIR), the target that just raises signal interference ratio (SIR), as long as there is a link requirement to reduce target signal interference ratio (SIR), that just reduces target signal interference ratio (SIR).

Also can adopt following comparatively conservative method, suppose that the exterior ring power control algolithm is SIRtempi to the single result of every link, i=1 ... n, also promptly have only three kinds of results, rising, constant and reduction, represent that with 1,0 and-1 last amalgamation result is represented with SIRtemp, adopts following formula respectively:

SIRtemp＝DTXSIR(SIRtemp1，SIRtemp2，…，SIRtempn)，

Wherein function DTXSIR is defined as follows:

If $\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{SIRtempi}>0.5,\mathrm{SIRtemp}=1;$

If $\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\mathrm{SIRtempi}<0.5,\mathrm{SIRtemp}=-1;$

If other value, SIRtemp=0;

When SIRtemp=1, rising target signal interference ratio SIR

Db; When SIRtemp=-1, reduce target signal interference ratio SIR Db; When SIRtemp=0, the target signal interference ratio remains unchanged.

The present invention proposes outer-loop power controlling method, overcome the control of common exterior ring power and do not considered the special processing that needs under discontinuous emission (DTX) situation, set up the unified exterior ring power control framework under non-DTX situation and the DTX situation, the conversion of real-time tracking environment.Determine the size of target signal interference ratio according to actual needs, thereby reach under the condition that guarantees communication quality, increase the purpose of power system capacity to greatest extent.

Description of drawings

Fig. 1 is the basic framework of uplink power control in the WCDMA system

Fig. 2 is the basic framework of exterior ring power control in the WCDMA system

Fig. 3 is the structure chart of exterior ring power control

Embodiment

Further specify the present invention below in conjunction with drawings and Examples.

Power control basic framework as shown in Figure 1 in the WCDMA system, at UTRAN end (UMTS Terrestrial radio access network), power control section between base station (NodeB) 2 and the radio network controller (RNC) 3 is divided into exterior ring power control, and the power control section between base station (NodeB) 2 and the travelling carriage (UE) 1 is divided into inner loop power control.

As shown in Figure 3, N is Transmission Time Interval (TTI) number of adjusting the required transmission of target SIR in the exterior ring power control, and N1 is the TTI number during the non-DTX, and N2 is the TTI number during the DTX; N1+N2=N here.

The operating process of present embodiment is as follows:

1. provide adjustment cycle (unit millisecond) T of exterior ring power control, T rounds then divided by Transmission Time Interval (TTI), just obtains carrying out the TTI number N that exterior ring power is adjusted required observation;

2.MAC layer is added up the transmission situation in N the TTI, judges that is a kind of in this N TTI right and wrong DTX situation, DTX situation, non-DTX and the DTX mixing situation.N back zero clearing of the every meter of MAC layer, counting again.

If 3. N1 ≠ 0, N2=0, right and wrong DTX situation is then implemented generally the exterior ring power control based on the BLER of DPDCH correspondence, and the size such as determine the target signal interference ratio according to the difference of measuring BLER and target BLER also is $\mathrm{SIRt}\arg \mathrm{et}(n+1)=\mathrm{SIRt}\arg \mathrm{et}\left(n\right)+(1-r)(\frac{\mathrm{BLER}}{\mathrm{BLERt}\arg \mathrm{et}}-1)\mathrm{SP}$ Step factor SP is obtained by emulation, be one greater than zero number.In this variable step, introduce to adjust factor r, one more than or equal to zero smaller or equal to 1 number, so that handle various situations flexibly.Here be that example illustrates this formula with communication quality index BLER only, if use when carrying out exterior ring power control based on the error rate (BER) and frame error rate (FER), the BLER in the above-mentioned formula substitutes with BER and FER and gets final product.

4. if, N1 ≠ 0, N2 ≠ 0 right and wrong DTX and DTX mix situation, then do not carry out exterior ring power control, because exterior ring power control is adjusted than very fast, the possibility that this situation generally periodically occurs is very little, and lacks accurate transformational relation between the BLER/FER/BER of corresponding BER of DPCCH and DPDCH correspondence, does not therefore carry out exterior ring power control.In fact, by speech business, because the adjustment cycle of exterior ring power control is shorter, people's time a few tens of milliseconds speaks, time a few tens of milliseconds is silent again, and this situation hardly may.Need to prove,, do not handle as DTX owing to " empty bag " phenomenon that the Iub interface transmission lag causes.

5. if N1=0, N2 ≠ 0 is DTX situation when soft handover (non-), then carries out the exterior ring power control based on the BER of DPCCH.The selection principle of desired value is: before the DTX, can obtain the BER (N the mean value that TTI is interior) of the DPCCH under the normal exterior ring power control, then the desired value BERtarget of this numerical value as BER, that is to say, BER when the nearest non-DTX of DTX, but under the situation that can't obtain, can only use representative value, such as, be the DTX situation at the very start.When the BLER/FER/BER of DPDCH correspondence was a certain constant, the BER of DPCCH can have a little excursion.Consider such characteristics, we adopt following processing method, to avoid unnecessary " table tennis " phenomenon.

If the BER that reports in the Frame is respectively BER1, BER2 ..., BERN, BERm=(BER1+ averages ... + BERN)/and N, as BERm＞BERtarget+BERtarget1, so target SIR is improved Db; When BERm＜BERtarget-BERtarget2, so target SIR is reduced

Db; Other situation target signal interference ratio remains unchanged.

Db is less than the step-length of inner loop power control, and it and BERtarget1, BERtargct2 all are algorithm parameters of being determined by emulation.Need to prove that when many transmission channels, MAC can obtain DPCCHBER from a plurality of Frames simultaneously, so we regulation DPCCH BER obtains from the pairing Frame of that transmission channel of measuring BLER/FER/BER.

6. if DTX situation (during soft handover) is then carried out same exterior ring power control based on DPCCH BER.The selection principle of desired value is: choosing desired value minimum in each bar link is the desired value of system.During soft handover, report as multilink under the situation of DPCCH BER, can handle each bar link respectively earlier and judge whether to require rising target signal interference ratio (SIR), utilize result to judge again.Concrete grammar is as follows:

(1) when all links all require to raise target SIR, just raise, as long as there is a link requirement to reduce target SIR, that just reduces target SIR.That is to say that at soft changing state, it is easier than rising target signal interference ratio to reduce the target signal interference ratio.This is based on such fact: the purpose of power control is exactly to make the transmitting power minimum under the situation that guarantees communication quality as far as possible.At soft changing state, as long as have one the road or the N road in several roads link-quality goodly just can communicate by letter normally, in order to save resource as far as possible, allow travelling carriage rising power when most link-qualities are relatively poor, and when certain bar or several quality are better, reduce power, to reduce interference to system.Can adopt following comparatively conservative method:

(2) suppose that the exterior ring power control algolithm is SIRtempi to the single result of every link, i=1-n also promptly has only three kinds of results, rising, constant and reduction, might as well represent that with 1,0 and-1 last amalgamation result is represented with SIRtemp, adopts following formula respectively:

SIRtemp＝DTXSIR(SIRtemp1，SIRtemp2，…，SIRtempn)，

Wherein function DTXSIR is defined as follows:

If $\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\mathrm{SIRtempi}>0.5,\mathrm{SIRtemp}=1;$

If $\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\mathrm{SIRtempi}<-0.5,\mathrm{SIRtemp}=-1;$

If other value, SIRtemp=0.When SIRtemp=1, the rising target SIR Db; When SIRtemp=-1, reduce target SIR

Db; When SIRtemp=0, the target signal interference ratio remains unchanged.

Above embodiment illustrates at UTRAN end (UMTS Terrestrial radio access network), but according to principle of reciprocity, method of the present invention is equally applicable to mobile you.

Claims (8)

1, the method of exterior ring power control in a kind of WCDMA system, it is characterized in that, launch continuously at signal and set up unified exterior ring power control under (non-DTX) and two kinds of situations of the discontinuous emission of signal (DTX), setting parameter N is for adjusting the number of the required Transmission Time Interval of target signal interference ratio (SIR) (TTI), parameter N 1 is launched Transmission Time Interval (TTI) number during (non-DTX) continuously for signal, parameter N 2 is Transmission Time Interval (TTI) number during the discontinuous emission of signal (DTX), satisfy N1+N2=N, system provides the adjustment cycle T of exterior ring power control, described adjustment cycle rounds after divided by described Transmission Time Interval (TTI) and obtains N, the MAC layer is added up the transmission situation in N the described Transmission Time Interval (TTI), simultaneously, described MAC layer is counted respectively N1 and N2 according to N, N back zero clearing of every meter, when

(a) N1 ≠ 0, N2=0, then respective signal is launched (non-DTX) situation continuously, and system is according to carrying out exterior ring power control based on the corresponding Block Error Rate/frame error rate/error rate (BLER/FER/BER) of Dedicated Physical Data Channel (DPDCH);

(b) N1 ≠ 0, N2 ≠ 0, then discontinuous emission of respective signal (DTX) and signal are launched (non-DTX) mixing situation continuously, and system does not carry out exterior ring power control;

(c) N1=0, N2 ≠ 0, the discontinuous emission of respective signal (DTX) situation then, system is according to carrying out exterior ring power control based on the corresponding error rate (BER) of Dedicated Physical Control Channel (DPCCH).

2, the method for exterior ring power control in a kind of WCDMA as claimed in claim 1 system, it is characterized in that, in (a) kind situation, signal is launched under (non-DTX) situation continuously, system can be according to carrying out exterior ring power control based on the corresponding Block Error Rate (BLER) of Dedicated Physical Data Channel (DPDCH), determine the size of target signal interference ratio SIR according to the difference of measuring block error rate BLER and target block error rate BLER target, promptly $\mathrm{SIRt}\arg \mathrm{et}(n+1)=\mathrm{SIRt}\arg \mathrm{et}\left(n\right)+(1-r)(\frac{\mathrm{BLER}}{\mathrm{BLERt}\arg \mathrm{et}}-1)\mathrm{SP}$ Step factor SP is the real number greater than zero, introduces in variable step and adjusts factor r, and r is smaller or equal to 1 real number more than or equal to zero.

3, the method for exterior ring power control in a kind of WCDMA as claimed in claim 1 system, it is characterized in that, in (a) kind situation, signal is launched under (non-DTX) situation continuously, system can be according to carrying out exterior ring power control based on the corresponding frame error rate (FER) of Dedicated Physical Data Channel (DPDCH), determine the size of target signal interference ratio SIR according to the difference of measuring frame error rate FER and target frame error rate FERtarget, promptly $\mathrm{SIRt}\arg \mathrm{et}(n+1)=\mathrm{SIRt}\arg \mathrm{et}\left(n\right)+(1-r)(\frac{\mathrm{FER}}{\mathrm{FERt}\arg \mathrm{et}}-1)\mathrm{SP}$ Step factor SP is the real number greater than zero, introduces in variable step and adjusts factor r, and r is smaller or equal to 1 real number more than or equal to zero.

4, the method for exterior ring power control in a kind of WCDMA as claimed in claim 1 system, it is characterized in that, in (a) kind situation, signal is launched under (non-DTX) situation continuously, system can be according to carrying out exterior ring power control based on the corresponding error rate (BER) of Dedicated Physical Data Channel (DPDCH), determine the size of target signal interference ratio SIR according to the difference of measuring error rate BER and target error rate BERtarget, promptly $\mathrm{SIRt}\arg \mathrm{et}(n+1)=\mathrm{SIRt}\arg \mathrm{et}\left(n\right)+(1-r)(\frac{\mathrm{BER}}{\mathrm{BERt}\arg \mathrm{et}}-1)\mathrm{SP}$ Step factor SP is the real number greater than zero, introduces in variable step and adjusts factor r, and r is smaller or equal to 1 real number more than or equal to zero.

5, the method for exterior ring power control in a kind of WCDMA as claimed in claim 1 system, it is characterized in that, (c) kind situation, when non-soft handover, system according to the method for carrying out exterior ring power control based on the corresponding error rate (BER) of Dedicated Physical Control Channel (DPCCH) is:

The discontinuous emission of signal (DTX) before, system can obtain the error rate (BER) of the Dedicated Physical Control Channel (DPCCH) under the normal exterior ring power control, be the mean value in the exterior ring power control adjustment cycle, then, establish the BER that reports in the Frame and be respectively BER1, BER2 the desired value BERtarget of this numerical value as the error rate (BER), BERN, BERm=(BER1+ averages ... + BERN)/N, then

As BERm＞BERtarget+BERtarget1, target signal interference ratio (SIR) is improved

Db;

When BERm＜BERtarget-BERtarget2, target signal interference ratio (SIR) is reduced

Db;

Target signal interference ratio (SIR) remains unchanged under other situation,

The step-length that db controls less than inner loop power, Db and BERtarget1, BERtarget2 all are parameters of being determined by emulation.

6, according to the method for exterior ring power control in a kind of WCDMA system described in the claim 5, it is characterized in that, in the discontinuous emission of signal (DTX) before, system can't obtain the error rate (BER) of the Dedicated Physical Control Channel (DPCCH) under the normal exterior ring power control, then the desired value BERtarget of representative value as the error rate (BER), the error rate (BER) that system obtained when described representative value referred to that signal is launched (DTX) continuously.

7, the method of exterior ring power control in a kind of WCDMA as claimed in claim 1 system, it is characterized in that, (c) kind situation, when soft handover, report as multilink under the situation of the error rate (BER) of Dedicated Physical Control Channel (DPCCH), choose the desired value of the error rate (BER) minimum in each bar link as system, this link target signal interference ratio (SIR) that whether requires to raise can be handled and judge to the MAC layer earlier respectively to each bar link, utilize result to judge again, when all links all require to raise target signal interference ratio (SIR), the target that just raises signal interference ratio (SIR), as long as there is a link requirement to reduce target signal interference ratio (SIR), that just reduces target signal interference ratio (SIR).

8, the method of exterior ring power control in a kind of WCDMA communication system as claimed in claim 1, it is characterized in that, (c) kind situation, when soft handover, report as multilink under the situation of the error rate (BER) of Dedicated Physical Control Channel (DPCCH), choose the desired value of the error rate (BER) minimum in each bar link as system, this link target signal interference ratio (SIR) that whether requires to raise can be handled and judge to the MAC layer earlier respectively to each bar link, utilize result to judge again, suppose that the exterior ring power control algolithm is SIRtempi to the single result of every link, i=1 ... n, also promptly have only three kinds of results, target signal interference ratio (SIR) raises, constant and reduce, use 1 respectively, 0 and-1 expression, last amalgamation result is represented with SIRtemp, adopts following formula:

SIRtemp＝DTXSIR(SIRtemp1，SIRtemp2，…，SIRtempn)，

Wherein function DTXSIR is defined as follows:

If $\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\mathrm{SIRtempi}>0.5,\mathrm{SIRtempi}=1;$

If $\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\mathrm{SIRtempi}<0.5,\mathrm{SIRtemp}=-1;$

If other value, SIRtemp=0;

When SIRtemp=1, rising target signal interference ratio SIR

Db; When SIRtemp=-1, reduce target signal interference ratio SIR Db; When SIRtemp=0, the target signal interference ratio remains unchanged.

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