CN100386975C - Power controlling method for soft switching of wideband CDMA system - Google Patents
Power controlling method for soft switching of wideband CDMA system Download PDFInfo
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- CN100386975C CN100386975C CNB2005100253044A CN200510025304A CN100386975C CN 100386975 C CN100386975 C CN 100386975C CN B2005100253044 A CNB2005100253044 A CN B2005100253044A CN 200510025304 A CN200510025304 A CN 200510025304A CN 100386975 C CN100386975 C CN 100386975C
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Abstract
The present invention relates to the field of communication and discloses a power control method for the soft switch of a WCDMA system. The present invention can carry out the power control to down transmitting power as soon as possible so as to avoid the longtime occurrence of the unbalanced condition of received signals among soft switch links. In the present invention, after path search is completed, the power control can be carried out to the down transmitting power in an attempting mode only when the SIR of an up link reaches a threshold value, and the power control does not need to be carried out by waiting for the completion of uplink synchronization.
Description
Technical field
The present invention relates to the communications field, particularly the power control techniques of mobile communication system.
Background technology
Along with the fast development of mobile communication business, the application of mobile data and multimedia communication will be more and more widely, in the near future, even will become the main business that mobile communication is carried above traditional speech.And traditional second generation global system for mobile communications (Global System for mobileCommunication, abbreviation " GSM ") mobile communications network can't adapt to this new development trend, for this reason, GSM will progressively carry out the transition to 3-G (Generation Three mobile communication system).Wherein, third generation partner program (3rd Generation Partnership Project, abbreviation " 3GPP ") Wideband Code Division Multiple Access (WCDMA) (the Wideband Code Division Multiple Access of institute's standard, be called for short " WCDMA ")/universal mobile telecommunications system (Universal Mobile Telecommunications System, be called for short " UMTS ") constantly improve and the mature technique standard with it, with its flexible net framework, level and smooth evolution pattern, many advantages such as effective investment, and develop into the major technique of 3G (Third Generation) Moblie gradually, and accepted by increasing mobile communication carrier and equipment supplier.
The WCDMA/UMTS system comprises Radio Access Network (Radio Access Network is called for short " RAN ") and core network (Core Network is called for short " CN ") two large divisions.Wherein, RAN mainly comprises two category nodes: base station (NodeB) and radio network controller (Radio NetworkController is called for short " RNC ").NodeB is responsible for the transmitting-receiving and the bottom layer treatment of wireless signal, for example modulation, coding and decoding etc.RNC is used for the management of on-air radio resource, for example, sends Cell Broadcast CB, distributes RAB between wireless channel, allocating cell parameter, managing mobile phone and the system or the like.
The WCDMA system is one, and all mobile subscribers take same band and frequency from disturbing system, are distinguished by different spreading codes, but owing to exist nonideal correlation properties between the spreading code, make near-far problem outstanding especially.The near-far interference here is meant that multiple access interference ratio rightabout that the user a little less than the strong user of power is to power brings is that multiple access that the user a little less than the power brings the strong user of power disturbs and wants big, so the required power control technology, the balance user power.This shows that the big young pathbreaker of user emission power directly influences the total capacity of system, thereby make power control techniques become one of of paramount importance core technology in the WCDMA system.
The target of power control is exactly under the condition that guarantees user communication quality in the WCDMA system, makes user's transmitting power as far as possible little.In the WCDMA system, 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 the transmitting power by the control physical channel, makes received signal interference ratio (Signal-to-Interference ratio is called for short " SIR ") converge on the desired value of SIR.External circule power control is by dynamically adjusting the sir target value of inner-loop power control, communication quality being met the demands all the time.
In mobile communication system, when travelling carriage is slowly walked out original Serving cell, in the time of will entering another Serving cell, the link between former base station and the travelling carriage will be replaced by the link between new base station and the travelling carriage, the implication that Here it is switches.The WCDMA system supports polytype switching, subscriber equipment (User Equipment when taking place according to switching, be called for short " UE ") with former NodeB is connected with target NodeB different, switching can be divided into following main type: direct-cut operation, soft handover, More Soft Handoff and free time switching etc.Wherein, soft handover refers to when UE begins to get in touch with a target NodeB, do not interrupt immediately with former NodeB between communicate by letter.Soft handover only can apply to have the WCDMA interchannel of same frequency.In addition, those of ordinary skill in the art are appreciated that the link between UE and the NodeB comprises up direction and down direction.Wherein, up direction is meant the direction that UE sends, NodeB receives; Down direction is meant the direction that NodeB sends, UE receives.
In soft switching process, the uneven and indirect number unbalanced situation of collecting mail of link of coupling loss between soft switching link may appear.
Those of ordinary skill in the art are appreciated that coupling loss is meant the ratio between transmitting of a link and the received signal.The coupling loss imbalance is meant between soft switching link: in soft handover, being provided with two links exists, if one the up coupling loss of link is descending greater than another link less than another link, if perhaps this link is up descending less than another link greater than another link, then think coupling loss imbalance between link.The coupling loss imbalance causes mainly due to the non-correlation of frequency division multiplexing (Frequency Division Duplex is called for short " FDD ") system's uplink and downlink rapid fading between link.
And the indirect collection of letters imbalance of soft switching link is meant: in soft handover, being provided with two links exists, if one the up received signal quality of link is worse than another link and descending another link that is better than, perhaps this link is up is better than another link and descending another link that is worse than, and then thinks indirectly collection of letters imbalance of link.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.
In actual applications, when being in soft changing state, UE and network side keep multi wireless links simultaneously.Power control algorithm can be referring to " 3GPP TS 25.214 Physical Layer Procedures (FDD) " (can be translated into " 3GPP TS 25.21 4 physical layer procedure (Frequency Division Duplexing (FDD)) ").For up inner-loop power control, UE receives the signal of a plurality of Radio Links, data field is carried out high specific merge, and the TPC that will take into account each Radio Link to control domain orders the uplink transmission power of adjusting UE.Yet because the quality of each down link may be different, so the transmitting power on certain link is controlled (Transmit PowerControl is called for short " TPC "), and order can be unreliable.When a TPC orders when unreliable, the way of different terminals is slightly had any different, some terminal is not used these insecure TPC orders fully, and some terminal has been carried out weighted to these insecure TPC orders, is equivalent to part and uses these insecure TPC orders.Generally speaking, when existing a TPC to order when unreliable, then the control of the power of UE mainly is controlled by the good TPC order of down link.
As previously mentioned, because a variety of causes in the process of soft handover, the link collection of letters number unbalanced situation indirectly can occur.Indirectly collect mail when number uneven when link occurring, because the transmitting power of UE is controlled by received signal down link preferably, corresponding uplink quality is poor, thereby can require the UE power per liter, make the UE transmitting power improve, strengthened interference, system resource is caused waste other users.
Those of ordinary skill in the art are appreciated that in the process of soft handover for network side, the foundation of new link comprises path search process and up initial synchronization.Accompanying drawing 1 is in the prior art, in the new link establishment process, and the method schematic diagram of inner loop power control.
As shown in the figure, the up link that newly adds link at soft handover is set up in the process, and newly-built up link 10 successively is in two stages: path search process and up initial synchronization.Begin to be set up to path search from new link and finish, this stage belongs to the path search process; Finish to up from path search and to finish synchronously, this stage belongs to up initial synchronization.In path search process and up initial synchronization, it is constant that NodeB remains down transmitting power 20, and NodeB sends complete 1 TPC command word 30 to UE simultaneously, is used to control the ascending power of UE, makes UE constantly promote transmitting power.After uplink synchronous was finished, NodeB controlled down transmitting power according to the TPC order that UE sends, and has promptly entered normal inner-loop power control; The TPC command word 30 that while NodeB sends to UE will generate according to the SIR quality of up reception.
In actual applications, there is following problem in such scheme: when beginning to set up owing to new link, initial down transmitting power 20 is that network side estimates that there is deviation in this value, in order to guarantee the quality of down link, should be worth the demand greater than reality usually.And in the prior art, in path search process and uplink synchronous process, keeping this down transmitting power that has deviation always, and be easy to take place soft switching link collection of letters imbalance indirectly, cause at the very big SIR point cutting edge of a knife or a sword of up appearance, promptly UE has wasted power.Cause serious interference to up when serious, influence the up-link capacity of system.
Cause the main cause of this situation to be, in the new link establishment process, before uplink synchronous is finished, use a down transmitting power that has deviation of estimating by network side always, in other words, down transmitting power is not carried out power control timely.
Summary of the invention
In view of this, main purpose of the present invention is to provide a kind of Poewr control method that is used for the broadband CDMA system soft handover, make it possible to as soon as possible down transmitting power be carried out power control, to avoid the occurring soft switching link collection of letters number unbalanced situation indirectly for a long time.
For achieving the above object, the invention provides a kind of Poewr control method that is used for the broadband CDMA system soft handover, when newly adding link, comprise two processes of path search and up initial synchronisation, wherein, after path search begins, it is constant to keep initial down transmitting power, after described path search is finished, before up initial synchronisation is finished, up link is carried out demodulation, whether monitoring upward signal interference ratio reaches default thresholding, and the emissive power control command word that obtains according to demodulation immediately in case the upward signal interference ratio reaches default thresholding carries out power control to described down transmitting power.
Wherein, described default thresholding can obtain by emulation.
In addition, described default thresholding also can be by the empirical value setting.
In addition, after described up initial synchronization was finished, the emissive power control command word that obtains according to demodulation carried out power control to described down transmitting power.
In addition, the described monitoring whether the upward signal interference ratio is reached default thresholding is carried out by the base station.
By relatively finding, the main distinction of technical scheme of the present invention and prior art is that the present invention is after path search is finished, as long as the SIR of up link reaches threshold value, promptly attempt down transmitting power is carried out power control, and need not wait for after uplink synchronous is finished and just begin power control.
Difference on this technical scheme, brought comparatively significantly beneficial effect, promptly newly add in the link process at soft handover, the present invention's descending power control that makes is as far as possible early worked, to avoid occurring soft switching link collection of letters imbalance indirectly for a long time, prevent the SIR point cutting edge of a knife or a sword that up appearance is very high, guarantee the up-link capacity of system.
Description of drawings
Fig. 1 is the method schematic diagram according to inner loop power control in the new link establishment process of soft handover of prior art;
Fig. 2 is the method schematic diagram according to inner loop power control in the new link establishment process of soft handover of the first embodiment of the present invention;
Fig. 3 is the power control flow process of band portion power control process according to a second embodiment of 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.
Basic principle of the present invention at first is described.The present invention is in order to carry out power control to down transmitting power as soon as possible, so after path search is finished, just judge the quality of up link, if SIR reaches predetermined value, just use TPC order that UE sends that the down transmitting power of down link is carried out power control, and needn't wait until that whole synchronizing process finishes.
Below in conjunction with accompanying drawing 2 an explanations preferred embodiment of the present invention, this embodiment has described the method for inner loop power control in the stylish link establishment process of soft handover.
As shown in the figure, the same with prior art, newly add setting up in the process of link at soft handover, newly-built up link 10 also successively is in two stages: path search process and up initial synchronization.The TPC command word 30 that sends to UE for NodeB in this two stages, all is in complete 1 state, is used to control the ascending power of UE, makes UE constantly promote transmitting power; After uplink synchronous was finished, this TPC command word 30 will generate according to the SIR quality of up reception.
For down transmitting power 20, in the path search process, because NodeB can't obtain the information that the UE side sends, can use the initial downlink transmitting power of an estimation this moment.
After path search is finished, enter up initial synchronization, because NodeB has found the position in footpath, and can carry out demodulation to up link.Judge the quality of reception of up link this moment, as long as the TPC order that up SIR greater than a thresholding, just uses UE to send controls down transmitting power 20, and needn't wait until that whole synchronizing process finishes.This process is called the control of part power.Above-mentioned thresholding obtains by emulation.Why will set up a thresholding, be because the correctness that will guarantee to order from the TPC that the up link demodulation is come out.If SIR is too low, the TPC command word that obtains from up link is likely nonsensical so.Set up a thresholding, balance correctness and ageing.Be understood that in according to another embodiment of the invention, above-mentioned thresholding also can be by the empirical value setting.
After uplink synchronous is finished, down transmitting power 20 is carried out normal inner-loop power control, i.e. the TPC order that sends according to UE is controlled down transmitting power.
In sum, key of the present invention is to have introduced the control of part power in up initial synchronization, makes down transmitting power 20 obtain power control as soon as possible.Further specify the power control flow process of band portion power control below in conjunction with accompanying drawing 3.
At first, after new link establishment begins, enter step 100, it is an initial value that NodeB keeps down transmitting power.This initial value is an estimated value.
Enter step 101 then, judge whether path search is finished,, otherwise return step 100 if finish then enter step 102.
In step 102, judge that up SIR whether greater than default threshold value, if then enter step 103, otherwise enters step 104.
In step 103, the TPC order that NodeB uses UE to send is controlled down transmitting power 20.By the judgement of step 101, NodeB has found the position in footpath as can be known, and can carry out demodulation to up link; By the judgement of step 102, the quality of up link has reached certain level as can be known, and the TPC command word of reconciling out from it is available.Step 103 has illustrated as long as path search is finished and the SIR of up link reaches thresholding, just can carry out power control to down transmitting power, and need not wait for after uplink synchronous is finished and just carry out power control.The implication of part power control process that Here it is.After this enter step 105.
In step 104, it is constant that NodeB continues to keep current down transmitting power, and enter step 105.Because SIR does not reach thresholding, illustrate promptly to enable from up link, to demodulate the TPC command word that its correctness also can not get guaranteeing, thereby can't carry out power control.
In step 105, NodeB judges whether up initial synchronisation is finished, if then enter step 106, otherwise enter step 102.
In step 106, carry out normal down transmitting power control, concrete grammar is identical with prior art, does not just describe in detail here.
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 (5)
1. a Poewr control method that is used for the broadband CDMA system soft handover comprises two processes of path search and up initial synchronisation when newly adding link, and wherein, after path search began, it was constant to keep initial down transmitting power,
It is characterized in that, after described path search is finished, before up initial synchronisation is finished, up link is carried out demodulation, whether monitoring upward signal interference ratio reaches default thresholding, and the emissive power control command word that obtains according to demodulation immediately in case the upward signal interference ratio reaches default thresholding carries out power control to described down transmitting power.
2. the Poewr control method that is used for the broadband CDMA system soft handover according to claim 1 is characterized in that, described default thresholding obtains by emulation.
3. the Poewr control method that is used for the broadband CDMA system soft handover according to claim 1 is characterized in that, described default thresholding is pressed the empirical value setting.
4. according to each described Poewr control method that is used for the broadband CDMA system soft handover in the claim 1 to 3, it is characterized in that, after described up initial synchronization was finished, the emissive power control command word that obtains according to demodulation carried out power control to described down transmitting power.
5. the Poewr control method that is used for the broadband CDMA system soft handover according to claim 1 is characterized in that, the described monitoring whether the upward signal interference ratio is reached default thresholding is carried out by the base station.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2005100253044A CN100386975C (en) | 2005-04-21 | 2005-04-21 | Power controlling method for soft switching of wideband CDMA system |
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| CNB2005100253044A CN100386975C (en) | 2005-04-21 | 2005-04-21 | Power controlling method for soft switching of wideband CDMA system |
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| CN100386975C true CN100386975C (en) | 2008-05-07 |
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| CN102084686A (en) * | 2009-09-30 | 2011-06-01 | 高通股份有限公司 | Method and apparatus for closed loop power control during TD-SCDMA baton handover |
| CN103533581A (en) * | 2012-07-02 | 2014-01-22 | 中兴通讯股份有限公司 | Method and apparatus for channel adjusting |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1304586A (en) * | 1998-04-07 | 2001-07-18 | 艾利森电话股份有限公司 | Downlink power control in cellular mobile radio communications system |
| CN1476687A (en) * | 2001-08-30 | 2004-02-18 | ���ǵ�����ʽ���� | Power controlling method during soft handoff in mobile communication system |
| CN1516354A (en) * | 1998-12-03 | 2004-07-28 | �����ɷ� | Method and device for controlling transmitting power under soft switchover state |
| EP1494371A1 (en) * | 2002-08-20 | 2005-01-05 | Matsushita Electric Industrial Co., Ltd. | Communication terminal device, base station device, and transmission power control method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1304586A (en) * | 1998-04-07 | 2001-07-18 | 艾利森电话股份有限公司 | Downlink power control in cellular mobile radio communications system |
| CN1516354A (en) * | 1998-12-03 | 2004-07-28 | �����ɷ� | Method and device for controlling transmitting power under soft switchover state |
| CN1476687A (en) * | 2001-08-30 | 2004-02-18 | ���ǵ�����ʽ���� | Power controlling method during soft handoff in mobile communication system |
| EP1494371A1 (en) * | 2002-08-20 | 2005-01-05 | Matsushita Electric Industrial Co., Ltd. | Communication terminal device, base station device, and transmission power control method |
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