CN100563118C - Soft handover downlink power control system and method thereof - Google Patents

Abstract

The present invention relates to the power control techniques in the mobile communication, a kind of soft handover downlink power control system and method thereof are disclosed, can take into account uplink downlink when making soft handover, avoid occurring the fluctuation of up link reception SIR owing to coupling loss between link is uneven, reduce the UE transmitting power, reduced the uplink interference of system.Among the present invention, when up received signal is very weak, stop the descending inner-loop power control to carry out according to up TPC, carry out descending inner-loop power control by the DPB algorithm.In addition descending minimum emissive power is made as the average transmit power that is lower than user in the switch area and deducts a side-play amount again.

Description

Soft handover downlink power control system and method thereof

Technical field

The present invention relates to the power control techniques in the mobile communication, particularly based on the power control techniques in the mobile communication system of code division multiple access.

Background technology

CDMA is the mobile communication technology that grows up on spread spectrum technic, and it utilizes spreading code to distinguish different user, and data are carried out passing through transmission of radio links behind the spread spectrum.CDMA technology has the confidentiality height, strong interference immunity, availability of frequency spectrum height, the network planning is simple, power system capacity is big and have characteristics such as elasticity, and become the mainstream technology of mobile communication future development, present several 3G (Third Generation) Moblie (TheThird Generation, be called for short " 3G ") technical standard, comprise CDMA 2000 (Code DivisionMultiple Access 2000, be called for short " CDMA2000 "), Wideband Code Division Multiple Access (WCDMA) (Wideband CodeDivision Multiple Access, be called for short " WCDMA ") and TD SDMA (TimeDivision Synchronous Code Division Multiple Access, abbreviation " TD-SCDMA ") all based on the CDMA access way.

All mobile subscribers take same band and frequency in the cdma system, distinguished by different spreading codes, but owing to exist nonideal correlation properties between the spreading code, a user's signal can cause certain interference to other user in the system, be that cdma system is a self-interference system, this causes the near-far problem of cdma system outstanding especially.Therefore the big young pathbreaker of transmitting power directly influences the total capacity of system in the cdma system, thereby makes power control (being called for short " power control ") technology become one of of paramount importance core technology in the cdma system.In general, power control can be divided into open loop and closed loop dual mode.The transmitting terminal of open loop power control obtains relevant information by the measurement received signal and independently determines transmitted power; Closed-loop power control then according to the feedback decision transmitted power of opposite end, forms the ring-type of a closure this moment in the operation relevant with power control.The target of power control is exactly under the service quality that the guarantees customer requirements condition of (Quality of Service is called for short " QoS ") in the cdma system, makes transmitting power as far as possible little, to reduce system interference, increases power system capacity.

In several 3G technology standards based on CDMA technology, WCDMA is the standard more widely of using at present, it has inherited existing global system for mobile communications (Global Systems for Mobilecommunications, be called for short " GSM ") the high and open good characteristics of standardization level, with the GSM network favorable compatibility and interoperability being arranged, is one of development trend of future mobile communications.In the WCDMA system, closed-loop power control can be divided into two big classes: inner-loop power control and external circule power control.The main effect of inner-loop power control is by sending transmitting power control (Transmit Power Control, abbreviation " TPC ") transmitting power of order control physical channel, make received signal interference ratio (Signal toInterference Ratio is called for short " SIR ") converge on target SIR.Because the complexity of wireless channel is only carried out inner-loop power control according to sir value and can not really be reacted link-quality.For example, for the low speed user of stationary user, rate travel 3 kilometer per hours (Km/H) and the highspeed user of rate travel 50Km/H, guaranteeing on the identical frame error rate basis of (Frame Error Rate is called for short " FER "), is different to the requirement of SIR.And final communication quality is by FER/ Block Error Rate (Block ErrorRate, be called for short " BLER ")/bit error rate (Bit Error Rate, be called for short " BER ") weigh, therefore be necessary dynamically to adjust the sir target value according to actual FER/BLER/BER value, promptly need external circule power control.External circule power control is by dynamically adjusting the sir target value of inner-loop power control, communication quality is met the demands all the time, promptly reaching the FER/BLER/BER value of regulation.Wherein, inner-loop power control is to carry out in the B node (Node B) at the WCDMA system base-station, and external circule power control carries out in radio network controller (Radio NetworkController is called for short " RNC ").Figure 1 shows that WCDMA system up-link closed-loop power control structure.Need to prove downlink closed loop power control and uplink closed loop power control structural similarity shown in Figure 1.

In cdma system, subscriber equipment (User Equipment, be called for short " UE ") need switch when a sub-district moves to another sub-district, and the link between former cell base station and the UE will be replaced by the link between new cell base station and the UE.In cdma system, because neighbor cell can use same frequency, therefore UE can be simultaneously when cell boarder switches and the base station of two sub-districts communicate, when UE begins to get in touch with the base station of a new sub-district like this, do not interrupt immediately with former cell base station between communicate by letter, thereby can guarantee the reliability switched, Here it is the distinctive soft hand-off of CDMA.

When soft handover, may there be multiple situation in the transmission quality of multilink.For example under the situation that has two links to exist, if the up coupling loss of a link and descending coupling loss, are then thought coupling loss balance between link all greater than (perhaps all less than) another link; Otherwise, if up coupling loss is descending greater than another link (perhaps up descending less than another link greater than another link) then think coupling loss imbalance between link less than another link.Wherein, coupling loss is meant the ratio between transmitting of up link or down link and the received signal, and it mainly is to be caused by large scale loss, shadow loss and rapid fading etc.Need to prove that for convenience of description, in this article, unless this link of specified otherwise is upstream or downstream, otherwise link is all represented a pair of up link and down link.The coupling loss imbalance mainly is that non-correlation by Frequency Division Duplexing (FDD) (Frequency Division Duplex, be called for short " FDD ") the inconsistent up-downgoing rapid fading that causes of system's up-downgoing frequency causes between link.

Simultaneously, when soft handover, also may there be multiple situation in the quality of reception of multilink.For example under the situation that has two links to exist,, then think link collection of letters balance indirectly if the up received signal and the down receiving signal of a link all are better than (perhaps all being worse than) another link; Otherwise another link is descending to be better than another link (perhaps up descending another link that is worse than of another link that is better than) then to think indirectly collection of letters imbalance of link if up received signal quality is worse than.The coupling loss imbalance can cause link collection of letters imbalance indirectly between link, in addition the inconsistent link collection of letters imbalance indirectly that also can cause of down transmitting power.

For the inner-loop power control algorithm under the single link situation, UE and network side are measured the quality of reception in real time and are reduced or rising power by the physical layer TPC order request transmitter that feeds back, so that the quality of reception just maintains the level of demand.Because have only a link, thus recipient's feedback can promptly and accurately be responded at transmit leg, thus adjust transmitting power apace, the convergence of inner loop power control is to meet the requirements of very easily.

Yet when soft changing state, UE and network side keep multi wireless links simultaneously, and the transmission quality of multilink and the quality of reception are also inconsistent, there is multiple situation, complexity is many under the inner loop power control ratio single-link situation, it not only will consider the quality of each bar link, also will consider how to take into account the strategy of each link.For up inner-loop power control, UE receives the signal of a plurality of Radio Links, and the TPC that take into account each Radio Link orders the uplink transmission power of adjusting UE, because the quality of each down link may be different, so the order of the TPC on certain link can be unreliable.When a TPC orders when unreliable, the way of different terminals is slightly had any different, and some terminal is not used these insecure TPC orders fully, and some terminal part uses these insecure TPC orders.Generally speaking, when the TPC on the link orders when unreliable, then the control of the power of UE mainly is controlled by the good TPC order of down link.For descending inner-loop power control, UE controls according to the quality sum of all down links, UE only send 1 TPC order and all-network side joint receiving end according to this order adjustment down transmitting power, because the quality of each up link is also inequality, there is error code in the TPC order that network side decodes, can cause different links to take different power control action, reduction down transmitting power that promptly may a link and an other link rising down transmitting power.

Power control during for soft handover, because third generation partner program (3rd GenerationPartnership Project, what abbreviation " 3GPP ") stipulate in the protocol specification is not very clear and definite, caused the algorithm performance of present business terminal to differ, this just needs the descending power control of network side can take into account the realization situation of existing each terminal.

Prior art scheme one adopts the descending power control algolithm of stipulating in the 3GPP standard.

Network side receives after the TPC order, adjusts descending transmitting power according to order.When descending power control mode (this value is by network configuration) when being 0, each time slot of network side is all estimated TPC order (this order is sent in up link by UE), transmitting power of each time slot renewal; When descending power control mode was 1, per 3 time slots of network side were estimated a TPC order, and per 3 time slots upgrade a transmitting power.Wherein, the descending power control model is by network configuration, and the TPC order is sent in up link by UE, and the estimated value of TPC is counted TPC _Est

As the estimated value TPC that estimates k TPC order _Est(k) afterwards, network side is adjusted into new transmitting power P (k) with unit for decibel current descending power P (k-1) of milli (dBm) by following formula:

P (k)=P (k-1)+P _TPC(k)+P _Bal(k), wherein $P_{\mathrm{TPC}}\left(k\right)=\left\{\begin{array}{ccc}+{\mathrm{\Δ}}_{\mathrm{TPC}}& \mathrm{if}& {\mathrm{TPC}}_{\mathrm{est}}\left(k\right)=1\\ -{\mathrm{\Δ}}_{\mathrm{TPC}}& \mathrm{if}& {\mathrm{TPC}}_{\mathrm{est}}\left(k\right)=0\end{array}\right.$

P _Bal(k) obtained by power equalization, need to prove, in the power equalization order that RNC issues, the parameter that Node B is played a crucial role has following several:

The maximum step-length of adjusting has defined at the power of a maximum and has adjusted the time, and unit is a timeslot number, and according to this timeslot number, within this step-length, the power adjustment of accumulative total is 1dB to the maximum, and this value does not comprise the adjustment amount of descending inner-loop power control.

Adjustment cycle has defined the cycle of using power equalization, and unit is a frame.

Resize ratio has defined convergency factor, and this value is big more, adjusts slowly more, and this value is more little, adjusts fast more.

If the power equalization adjustment activates, then P _Bal(k) should be added in the inner-loop power control function, otherwise not consider P _Bal(k).P _BalComputing formula as follows:

∑ P _Bal=(1-r) (P _Ref+ P _P-CPICH-P _Init), its precision is ± 0.5dB.

Wherein, P _RefBe descending power reference value with respect to pilot power, P _P-CPICHBe the public guide frequency performance number, P _InitBe the descending code domain power of last time slot in the last adjustment cycle, r is the resize ratio value.Adjustment amount in the adjustment cycle is in maximum is adjusted the step-length scope and within the down transmitting power scope.

The power adjustment should equal 0 frame behind Connection Frame Number (Connection Frame Number is called for short " CFN ") mould adjustment cycle first time slot begins, and repeats adjustment cycle then, and restarts at first time slot of CFN=0.

The composition schematic diagram of network side internal loop power control system as shown in Figure 2 in the WCDMA system of prior art scheme one.Wherein, the network side internal loop power control system comprises with lower module in the WCDMA system:

Be used for the DPCCH Despread and demodulator 10 that the Dedicated Physical Control Channel (Dedicated Physical ControlChannel is called for short " DPCCH ") to up received signal carries out despreading and demodulation;

Be used for the SIR estimation module 20 that the SIR to up received signal estimates;

Be used for comparator module 30-1 that SIR estimated value and sir target value are compared;

Be used to generate the TPC order generation module 40 of the TPC order of controlling up-link transmission power;

The TPC that is used for extracting up received signal TPC order and obtaining its estimated value orders demodulation output module 50;

Be used for down transmitting power is carried out balanced power equalization module 60;

Be used for ordering the result of the output of demodulation output module 50 and power equalization module 60 to calculate the down transmitting power computing module 70 of down transmitting power according to TPC.

It is reasonably that prior art scheme one all reaches in the descending quality of reception under the situation of reliable request, adopts descending power equilibrium (Downlink Power Balance is called for short " DPB ") technology also can effectively solve the problem of descending power drift.About the particular content of prior art scheme one, can be with reference to 3GPP standard document 3GPP technical standard (Technical Specification is called for short " TS ") 25.214 and 3GPP TS 25.433.

In the Downlink Power Control Schemes of prior art scheme two, the down transmitting power of each link is inequality.Down transmitting power is according to down link coupling loss, and the link little to coupling loss sends higher transmitting power, and the link big to coupling loss adopts less transmitting power.This method helps the raising of descending performance.The thinking of prior art scheme two is fairly simple, do not describe in detail at this, about specifying of prior art scheme two, can be referring to " Soft Handover Issues in Radio ResourceManagement for 3G WCDMA ", Chinese can be translated into " the soft handover problem in the 3G WCDMA RRM ".The document is one piece of thesis for the doctorate, and the author is " Yue Chen ", and the source is as follows:

Department?of?Electronic?Engineering

Queen?Mary，University?of?London

September?2003

In actual applications, there is following problem in such scheme: the prior art scheme can cause the waste of UE transmitting power, increases uplink interference.

Cause the main cause of this situation to be, the unbalanced situation of coupling loss between link when prior art scheme one and prior art scheme two are not all considered soft handover, and the coupling loss imbalance is inevitable in practice between soft switching link, so just may cause the received signal imbalance, this moment is because the uplink transmission power of UE is controlled by received signal down link preferably, and the uplink quality of this down link correspondence is poor, the received signal of this up link of network side is also poor, can require UE to promote uplink transmission power, and in fact the uplink quality of another link is better, received signal can meet the demands fully, UE does not need bring to power, the power adjustment of this mistake can last till till the received signal balance, will cause the waste of UE transmitting power like this, increase the fluctuation of up link reception SIR simultaneously, increased uplink interference.

Summary of the invention

In view of this, main purpose of the present invention is to provide a kind of soft handover downlink power control system and method thereof, can take into account uplink downlink when making soft handover, avoid occurring the fluctuation of UE up link reception SIR owing to coupling loss between link is uneven, reduce the UE transmitting power, reduced the uplink interference of system.

For achieving the above object, the invention provides a kind of soft handover downlink power control system, comprise the signal-to-jamming ratio estimation module, emissive power control command demodulation output module, the power equalization module, described system also comprises:

The descending power control module, when being used for signal-to-jamming ratio estimated value at the link upward signal greater than predefined thresholding, export the power per liter order identical or fall power command with the output of described emissive power control command demodulation output module, when the signal-to-jamming ratio estimated value of upward signal was less than described thresholding in described link, output does not rise did not fall order;

The down transmitting power computing module is used for when carrying out the control of descending inner loop power calculating down transmitting power according to the output of described descending power control module in conjunction with the output of described power equalization module.

Wherein, described thresholding is less than the sir target value.

In addition, described power equalization module adopts the descending power equalization algorithm, and its parameter setting meets the following conditions:

Make that under the prerequisite that guarantees described system operate as normal the balanced dynamics of adjusting of descending power is big as far as possible.

In addition, the reference power of the described power equalization module down transmitting power mean value that is set at current link deducts a side-play amount.

In addition, the reference power of described power equalization module is set at the minimum down transmitting power of current link.

In addition, described minimum down transmitting power is set at that user's average transmit power deducts a side-play amount in the switch area.

In addition, the resize ratio r of described power equalization module can be set to 0.

In addition, the parameter of described descending inner loop power control meets the following conditions:

Under the prerequisite that does not influence inner-loop power control, maximum adjustment step-length is as far as possible little;

Under the prerequisite of power adjustment capability in satisfying a described adjustment cycle greater than maximum adjusting range that may needs, adjustment cycle is as far as possible little.

In addition, described system can be applicable in the broadband CDMA system.

The present invention also provides a kind of soft handover downlink Poewr control method, comprises following steps:

A starts the descending power equilibrium of all links when soft handover;

Whether B judges the signal-to-jamming ratio estimated value of link upward signal greater than predefined thresholding, if then carry out the descending inner loop power control of this link, otherwise stops the descending inner loop power control of this link;

Wherein, when carrying out the control of descending inner loop power, according to the emissive power control command that from the upward signal that receives, demodulates, in conjunction with the balanced down transmitting power that calculates of descending power; When stopping the control of descending inner loop power, only according to the balanced down transmitting power that calculates of descending power.

Wherein, described thresholding is less than the sir target value.

By relatively can finding, the main distinction of technical scheme of the present invention and prior art is, stops the descending inner-loop power control to carry out according to up TPC when up received signal is very weak, carries out descending inner-loop power control by the DPB algorithm.In addition descending minimum emissive power is made as the average transmit power that is lower than user in the switch area and deducts a side-play amount again.

Difference on this technical scheme has brought comparatively significantly beneficial effect, and promptly the first, the present invention program is based on existing protocol, and is less to the change of existing equipment and flow process, is very beneficial for upgrading and realizes.

The second, the present invention program is identical with the effect of existing scheme when soft handover coupling loss balance, to network performance without any influence, can backward compatibility existing network and equipment, help smooth upgrade on the basis of existing technology.

The 3rd, the present invention program is when the serious imbalance of soft switching link coupling loss, do not carry out descending inner-loop power control for up weak, descending strong link, because the effect of DPB algorithm can be very soon the down transmitting power of this link is drawn back a lower reference power, the TPC order of avoiding this link to send makes the bring to power of UE mistake, thereby can effectively avoid because the UE uplink transmission power waste that the coupling loss imbalance causes between link has reduced uplink interference.

At last, the present invention program can provide desirable uplink power control to UE under various link condition, low speed moves scene has very big meaning in that the many user's dense cities of switching zone customer, Microcell up-link capacity be limited etc., to improve the capacity of system greatly, improve up handoff gain.

Description of drawings

Fig. 1 is a WCDMA system up-link closed-loop power control structural representation;

Fig. 2 is the composition schematic diagram of network side internal loop power control system in the WCDMA system;

Fig. 3 is that the system of the soft handover downlink power control of first preferred embodiment according to the present invention forms schematic diagram;

Fig. 4 is the flow process of method of the soft handover downlink power control of first preferred embodiment according to the present invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing.

Whether the present invention program's network side Node B has strong footpath to determine the output of descending power according to upward signal when receiving the UE upward signal, adopts the DPB algorithm to make balanced down transmitting power simultaneously.When upward signal does not have strong footpath, stop descending inner loop power control; Otherwise with regard to TPC order the carrying out power control of carrying according to the upward signal that receives.Adopt the present invention program, there is not strong footpath at upward signal, be that up coupling loss is when very big, stop descending inner-loop power control, when even coupling loss is uneven between link like this, because can drawing back down transmitting power the lower reference of setting, puts the DPB algorithm, can make the received signal between link reach balance very soon, can not cause the waste of UE transmitting power, reduce uplink interference.

The composition of the soft handover downlink power control system of first preferred embodiment as shown in Figure 3 according to the present invention.This preferred embodiment realizes in the WCDMA system.To need to prove that in order comparing with prior art scheme one, this system has not only comprised the correlation module of soft handover downlink power control, also to have comprised some and be used to generate the correlation module of the TPC order of controlling the UE ascending power.

Soft handover downlink power control system comprises with lower module: DPCCH Despread and demodulator 10, SIR estimation module 20, comparator module 30-1 and 30-2, TPC orders generation module 40, TPC order demodulation output module 50, power equalization module 60, down transmitting power computing module 70 and descending power control module 80.Wherein, DPCCH Despread and demodulator 10, SIR estimation module 20, comparator module 30-1, TPC order generation module 40, TPC order demodulation output module 50 and power equalization module 60 modules equal and in the prior art scheme one are identical, only do brief description below.

DPCCH Despread and demodulator 10 is used for the DPCCH of up received signal is carried out despreading and demodulation.Those of ordinary skill in the art understands, and has comprised the control information of the physical layer of some UE transmissions in the DPCCH of up received signal, for example controls the TPC order of down-link transmitting power.

SIR estimation module 20 is used for estimating according to the output of DPCCH Despread and demodulator 10 SIR of up received signal.Wherein, the estimated value of the SIR of up received signal is an important physical layer measured value, can be used to generate the TPC order of control up-link transmission power etc.

Comparator module 30-1 is used for the SIR estimated value and the sir target value of 20 outputs of SIR estimation module are compared, and comparative result is sent to TPC order generation module.Wherein, the sir target value is set by external circule power control, is promptly set according to FER/BLER/BER by RNC.In first preferred embodiment of the present invention, respectively with SIR _EstAnd SIR _TargetIf the SIR estimated value and the sir target value of 20 outputs of expression SIR estimation module are SIR _EstGreater than (or equaling) SIR _TargetIllustrate that then up-link transmit power above requiring, can reduce the transmitted power of up link; Otherwise need to promote the transmitted power of up link.

Comparator module 30-2 is used for the SIR estimated value of SIR estimation module 20 outputs and strong footpath SIR thresholding are compared, and comparative result is sent to descending power control module 80.Those having ordinary skill in the art will appreciate that, in a plurality of transmission paths of wireless transmission, the SIR of the transmission path that signal is stronger (strong footpath) can reflect the coupling loss of this Radio Link to a certain extent, also can reflect the reliability of this transmission of radio links.In the present invention, the effect of comparator module 30-2 just is to judge whether up received signal is reliable, if SIR estimated value SIR _EstLess than strong footpath SIR thresholding, then the estimated value of the TPC order in explanation up received signal this moment is unreliable, is not enough to the basis as inner loop power control; Otherwise just can think that the estimated value of the TPC order in the up received signal is reliable, can be used as the basis of inner loop power control.In order to prevent under the serious unbalanced situation of coupling loss, the link of up difference still requires the TPC order of UE bring to power with down link transmission preferably, strong footpath SIR thresholding is made as the sir value of the link of the serious up difference when uneven of coupling loss, in first preferred embodiment of the present invention, footpath SIR thresholding is made as the sir target value and deducts a side-play amount by force, wherein, this side-play amount can utilize emulation tool emulation such as MATLAB to obtain.

TPC order generation module 40 is used for generating according to the comparative result of comparator 30-1 output the TPC order of control up-link transmission power.Wherein, if SIR _EstGreater than (or equaling) SIR _TargetThen the TPC order is set at 0, promptly requires to reduce the transmitted power of up link; Otherwise the TPC order is set at 1, promptly requires to promote the transmitted power of up link.

TPC order demodulation output module 50 is used for extracting from the output of DPCCH Despread and demodulator 10 estimated value of TPC order the up received signal.In first preferred embodiment of the present invention, with TPC _EstThe estimated value of representing the TPC order in the up received signal.

Correction value when power equalization module 60 is used for according to the equilibrium of DPB algorithm computation down transmitting power.The purpose that persons of ordinary skill in the art may appreciate that the DPB algorithm is to adjust down transmitting power to draw close to the reference power of a down transmitting power.For the principle of disturbing in the minimizing system, reference power should be set at a less value.In first preferred embodiment of the present invention, the down transmitting power average that reference power is set at current link deducts a side-play amount, wherein, can suppose that down transmitting power is that Rayleigh (Rayleigh) distributes, and obtains side-play amount by emulation.In second preferred embodiment of the present invention, reference power is set at the minimum emissive power of down link, wherein, the minimum emissive power of down link is lower than that user's average transmit power deducts a side-play amount in the switch area, and this side-play amount is identical with side-play amount in the present invention's first preferred embodiment.In order to be undertaken rapidly down transmitting power being adjusted to reference power in the inner-loop power control by TPC order stopping, can consider respectively from inner-loop power control and two angles of power equalization, in first preferred embodiment of the present invention, the maximum of power equalization is adjusted the principle of step-length setting for the smaller the better under the situation that does not influence inner-loop power control, and the principle that adjustment cycle is provided be the smaller the better under the situation of power adjustment capability greater than maximum adjusting range that may needs in a satisfied adjustment cycle; The resize ratio of power equalization is made as 0.

Down transmitting power computing module 70 is used for when carrying out the control of descending inner loop power calculating the down transmitting power value according to the output of descending power control module 80 in conjunction with the output of power equalization module 60.Wherein, descending power control module 80 has the power per liter order, falls power command or do not rise and do not fall three kinds of outputs of order, whether and how control down transmitting power computing module 70 carries out descending inner-loop power control, power per liter order and fall power command and respectively adjust down transmitting power during the indicating downlink inner-loop power control and rise and descend, do not rise do not fall order then the indicating downlink transmitting power do not rise and do not fall, also promptly stop descending inner-loop power control; The output of power equalization module 60 control down transmitting power computing module 70 with down transmitting power to the reference power adjustment.According to TPC order the carrying out down transmitting power adjustment of up received signal, then the method for descending power adjustment is identical with prior art scheme one, promptly if desired

P(k)＝P(k-1)+P _TPC(k)+P _bal(k)，

Wherein $P_{\mathrm{TPC}}\left(k\right)=\left\{\begin{array}{ccc}+{\mathrm{\Δ}}_{\mathrm{TPC}}& \mathrm{if}& {\mathrm{TPC}}_{\mathrm{est}}\left(k\right)=1\\ -{\mathrm{\Δ}}_{\mathrm{TPC}}& \mathrm{if}& {\mathrm{TPC}}_{\mathrm{est}}\left(k\right)=0\end{array}\right.,$

Wherein, TPC _Est(k) be the estimated value of k TPC order of up received signal.

If do not need to carry out descending inner-loop power control, then as long as with P _TPC(k) being changed to 0 gets final product.

Persons of ordinary skill in the art may appreciate that the descending power that the speed of utilizing DPB algorithm power equalization will be slower than TPC order control regulates the speed, order when reliable at the TPC of up received signal like this, use TPC order estimated value to carry out inner loop power control; Order when unreliable at the TPC of up received signal, stop descending inner-loop power control, this moment down output power since the effect of DPB algorithm to the reference power adjustment.

The descending power control module, when being used for signal-to-jamming ratio estimated value at the link upward signal greater than predefined thresholding, export the power per liter order identical or fall power command with the output of described emissive power control command demodulation output module, when the signal-to-jamming ratio estimated value of upward signal was less than described thresholding in described link, output does not rise did not fall order;

Descending power control module 80 is used for generating the control signal of adjusting down-link transmitting power according to the TPC order estimated value of the comparative result of comparator module 30-2 and 50 outputs of TPC order demodulation output module.In first preferred embodiment of the present invention, if the comparative result of comparator module 30-2 is that then inner-loop power control is not carried out in output, does not promptly rise and does not fall order less than strong footpath thresholding; Otherwise directly export the TPC order of TPC order demodulation output module 50 outputs, i.e. power per liter order or fall power command.Those of ordinary skill in the art understands, in first preferred embodiment of the present invention, descending power control module 80 can equivalence be a module that the output that has an Enable Pin equals to import, wherein, the comparative result of comparator module 30-2 is the Enable Pin control signal, the TPC order estimated value of TPC order demodulation output module 50 outputs is an input end signal, if the comparative result of comparator module 30-2 is that the SIR estimated value is greater than strong footpath SIR thresholding, then Enable Pin is effective, this moment, descending power control module 80 output TPC ordered estimated values, be the power per liter order or fall power command, otherwise Enable Pin is invalid, descending power control module 80 output high-impedance states promptly can be represented not rise not fall order.

Match with the soft handover downlink power control system of first preferred embodiment of the invention described above according to the flow process of the soft handover downlink Poewr control method of first preferred embodiment of the present invention as shown in Figure 4.

At first enter step 400, when soft handover, start the DPB of all links.Wherein, the detailed content of DPB algorithm can be referring to 3GPP technical standard (Technical Specification is called for short " TS ") 25.214 and 3GPP TS 25.433.Persons of ordinary skill in the art may appreciate that the purpose of using the DPB algorithm is to adjust down transmitting power to draw close to the reference power of a down transmitting power.For the purpose of disturbing in the minimizing system, reference power should be set at a less value.In first preferred embodiment of the present invention, the down transmitting power average that reference power is set at current link deducts a side-play amount, wherein, can suppose that down transmitting power is that Rayleigh (Rayleigh) distributes, and obtains side-play amount by emulation.In second preferred embodiment of the present invention, reference power is set at the minimum emissive power of down link, wherein, the minimum emissive power of down link is lower than that user's average transmit power deducts a side-play amount in the switch area, and this side-play amount is identical with side-play amount in the present invention's first preferred embodiment.In order to be undertaken rapidly down transmitting power being adjusted to reference power in the inner-loop power control by TPC order stopping, in first preferred embodiment of the present invention, the maximum principle of step-length setting of adjusting is for the smaller the better under the situation that does not influence inner-loop power control; The principle that adjustment cycle is provided be the smaller the better under the situation of power adjustment capability greater than maximum adjusting range that may needs in a satisfied adjustment cycle; Resize ratio is made as 0.

Then enter step 410, estimate the SIR of up received signal.Wherein, the estimation of the SIR of up received signal is that an important physical layer is measured, and its method is known in this field, does not describe in detail at this.

Then enter step 420, whether the SIR of more up received signal if then enter step 430, otherwise enters step 440 greater than strong footpath SIR thresholding.The SIR that persons of ordinary skill in the art may appreciate that strong footpath can reflect the coupling loss of this Radio Link to a certain extent, also can reflect the reliability of this transmission of radio links.This step is used to judge whether up received signal is reliable, if the SIR of up received signal, illustrates then that the estimated value of the TPC order in up received signal this moment is unreliable less than strong footpath SIR thresholding, is not enough to the basis as inner loop power control; Otherwise just think that the estimated value of the TPC order in the up received signal is reliable, can be used as the basis of inner loop power control.In order to prevent under the serious unbalanced situation of coupling loss, the link of up difference still requires the TPC order of UE bring to power with down link transmission preferably, strong footpath SIR thresholding is made as the sir value of the link of the serious up difference when uneven of coupling loss, in first preferred embodiment of the present invention, footpath SIR thresholding is made as the sir target value and deducts a side-play amount by force, wherein, this side-play amount can utilize emulation tool emulation such as MATLAB to obtain.

If the SIR of up received signal then in step 430, carries out descending inner-loop power control according to the TPC estimated value of up received signal greater than strong footpath SIR thresholding.If the SIR of up received signal, thinks then that the estimated value of TPC order of up received signal is reliable greater than strong footpath SIR thresholding, carry out descending inner-loop power control.The formula of descending inner-loop power control is identical with prior art scheme one, promptly

P (k)=P (k-1)+P _TPC(k)+P _Bal(k), wherein,

$P_{\mathrm{TPC}}\left(k\right)=\left\{\begin{array}{ccc}+{\mathrm{\Δ}}_{\mathrm{TPC}}& \mathrm{if}& {\mathrm{TPC}}_{\mathrm{est}}\left(k\right)=1\\ -{\mathrm{\Δ}}_{\mathrm{TPC}}& \mathrm{if}& {\mathrm{TPC}}_{\mathrm{est}}\left(k\right)=0\end{array}\right.,$

Wherein, TPC _Est(k) be the estimated value of k TPC order of up received signal.

If the SIR of up received signal is not more than strong footpath SIR thresholding,, do not carry out descending inner-loop power control then in step 440.In this step, think that the estimated value of TPC order of up received signal is unreliable, do not carry out descending inner-loop power control.Owing in step 400, started the DPB of all links, therefore still carried out down transmitting power equilibrium, i.e. P (k)=P (k-1)+P _Bal(k).By the effect of DPB, down transmitting power can be drawn to reference power value very soon.

Need to prove that step 410 works in whole handoff procedure to the flow process of step 440 always.That is to say, can't process ends after step 430 and step 440 execute, continue to carry out but get back to step 410.

Use the present invention program, when serious coupling loss imbalance appearred in soft handover, the down link of the link correspondence of up difference (the being made as link 1) quality of reception was good, stops descending inner-loop power control; On down link (the being made as link 2) quality of reception of the link correspondence of acting charitably poor, still carry out power control.Effect by the DPB algorithm, can be fast the down transmitting power of link 1 be drawn to reference power, this moment link 1 downlink quality variation, UE can require link 2 power per liter, inner-loop power control speed is faster than the DPB effect, thereby can fast the transmitting power of link 2 be adjusted to desired value.Descending the improving of UE sidelinks 2 reaches uplink and downlink received signal balance at this moment, up SIR fluctuation can not occur.When wherein poor uplink quality recovered, descending inner-loop power control worked, and can make the down transmitting power of all links reach balance in an adjustment cycle.

Though by with reference to some preferred embodiment of the present invention, the present invention is illustrated and describes, those of ordinary skill in the art should be understood that and can do various changes to it in the form and details, and without departing from the spirit and scope of the present invention.

Claims (10)

1. a soft handover downlink power control system comprises the signal-to-jamming ratio estimation module, emissive power control command demodulation output module, and the power equalization module,

It is characterized in that described system also comprises:

The descending power control module, when being used for signal-to-jamming ratio estimated value at the link upward signal greater than predefined thresholding, export the power per liter order identical or fall power command with the output of described emissive power control command demodulation output module, when the signal-to-jamming ratio estimated value of upward signal was less than described thresholding in described link, output does not rise did not fall order;

The down transmitting power computing module is used for when carrying out the control of descending inner loop power calculating down transmitting power according to the output of described descending power control module in conjunction with the output of described power equalization module.

2. soft handover downlink power control system according to claim 1 is characterized in that described thresholding is less than the sir target value.

3. soft handover downlink power control system according to claim 1 is characterized in that, described power equalization module adopts the descending power equalization algorithm, and its parameter setting meets the following conditions:

Make that under the prerequisite that guarantees described system operate as normal the balanced dynamics of adjusting of descending power is big as far as possible.

4. soft handover downlink power control system according to claim 3 is characterized in that, the down transmitting power mean value that the reference power of described power equalization module is set at current link deducts a side-play amount.

5. soft handover downlink power control system according to claim 3 is characterized in that, the reference power of described power equalization module is set at the minimum down transmitting power of current link.

6. soft handover downlink power control system according to claim 5 is characterized in that, described minimum down transmitting power is set at that user's average transmit power deducts a side-play amount in the switch area.

7. soft handover downlink power control system according to claim 1 is characterized in that, the parameter of described descending inner loop power control meets the following conditions:

Under the prerequisite that does not influence inner-loop power control, maximum adjustment step-length is as far as possible little;

Under the prerequisite of power adjustment capability in satisfying a described adjustment cycle greater than maximum adjusting range that may needs, adjustment cycle is as far as possible little.

8. soft handover downlink power control system according to claim 1 is characterized in that described system can be applicable in the broadband CDMA system.

9. a soft handover downlink Poewr control method is characterized in that, comprises following steps:

A starts the descending power equilibrium of all links when soft handover;

Whether B judges the signal-to-jamming ratio estimated value of link upward signal greater than predefined thresholding, if then carry out the descending inner loop power control of this link, otherwise stops the descending inner loop power control of this link;

Wherein, when carrying out the control of descending inner loop power, according to the emissive power control command that from the upward signal that receives, demodulates, in conjunction with the balanced down transmitting power that calculates of descending power; When stopping the control of descending inner loop power, only according to the balanced down transmitting power that calculates of descending power.

10. soft handover downlink Poewr control method according to claim 9 is characterized in that described thresholding is less than the sir target value.

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