The dynamic optimization method and the device of power control
Invention field
The present invention relates to mobile radio system, relate in particular in the 3-G (Generation Three mobile communication system) method and apparatus that carries out dynamic optimization is controlled in base station and transmission power of mobile station.
Background technology
In recent years, the progress of information technology has driven the fast development of mobile communication, and radio communication has been deep into the every aspect of industry, commercial affairs and personal lifestyle, and 3-G (Generation Three mobile communication system) has caused people in the industry's extensive concern.
For 3-G (Generation Three mobile communication system), it can provide flexile business such as data service, multimedia service, higher quality of service, the bigger wireless coverage etc. for the user except having, a very outstanding target is the power system capacity that can provide bigger, to satisfy growing traffic needs.
For portable terminal, its a very important design object is low-power consumption.Lower power consumption produces the energy loss that reduces, and to prolong the battery useful life of portable terminal, reduces the electromagnetic radiation to the hand-held person of terminal, realizes well received day by day environmental protection.
And in cdma system, all users are owing to adopt the multi-access mode of code division multiplexing to communicate, and promptly all users transmit and receive signal in identical time, similar frequency bands.The signal of each user's emission all can produce interference to other users, and promptly usually said multiple access disturbs.So the signal energy from nearer travelling carriage that the base station receives is flooded the signal from travelling carriage far away probably, produces so-called " near-far interference ".
Can be by the signal transmission power of each travelling carriage transmitter in the control system, the signal quality and the multiple access that make the power of expecting communication link remain on expectation in floor level, the system disturb the acceptable level that maintains, thereby guarantee the capability of communication system maximum.
The following existing power control techniques of commenting one by one, consider and handled the problem of above-mentioned power control to a certain extent, but still have many deficiencies:
It is 98100181 Chinese invention patent that name is called " transmit power controlling method ", application number, proposed at the dynamic power control method that adopts frequency division multiplexing mode second generation mobile communication system (gsm system), adopted the certain power step-length of mobile radio station is associated as power substep group, and then specified nominal transmitted power level in the described power substep group.This power control thought still has reference to the 3-G (Generation Three mobile communication system) (cdma system) that adopts code division multiplexing, but control procedure is complicated, and operability is relatively poor;
Name is called " carry out power control method and apparatus ", application number in mobile communication system be 96192934 Chinese invention patent, a kind of closed loop real-time power control method has been proposed, its is to the detection of motion velocity of mobile station and the frame error rate tolerance as the link-quality factor, and adjusts transmitting power according to these link-quality factors.The thought of this invention has certain advance, but will realize still having certain difficulty for the accurate tolerance of above-mentioned link-quality, causes the additional delay in the power control process easily, causes the power control fails;
It is 98810116 Chinese invention patent that name is called " optimize power control equipment and method ", application number, has proposed a kind of method that is used for regulating the communication system threshold value.Promptly determine the performance of communication system, state the value that performance evaluation is regulated threshold value by system again, then with respect to described threshold value adjustment transmitter power according to predetermined tolerance.This method can realize the transmitting power dynamic adjustments in the power control process, but the power adjustments amplitude is restive, is difficult to the requirement of guaranteed output control precision, does not reach the purpose of system optimization;
It is 98810118 Chinese patent that name is called " be used for power control mode select apparatus and method ", application number, propose a kind of method that the transmitter power control model is selected that is used for, it is characterized in that providing first pattern of one or more first power increments and second pattern of one or more second power increments.Whether promptly at first determine systematic function at rated range, if in rated range then select first power control mode (tracing mode) to control transmitter power; If systematic function is not at rated range then select second power control mode (burst mode) to control transmitter power.This Poewr control method has certain new meaning, but the power control pattern that is adopted when wireless channel environment is better than the noise level of system's expection is optimized inadequately, transmitting power still may be too high, and too much transmitting power can cause system capacity loss, and this to be 3-G (Generation Three mobile communication system) do not expect.
Name is called the United States Patent (USP) that " transmit power controlling method and in communication system ", application number are 5566165 application, has proposed a kind of cdma system Poewr control method.Promptly calculate the SIR of actual desired signal; Determine that actual SIR is whether greater than the reference SIR of the predefined communication quality that meets the expectation; The result produces the tpc bit word based on the comparison; The base station is the insertion forward frame of power control bit property word cycle; Tpc bit according to forward frame calculates tentative back emitted power; Determine back emitted power, promptly, get tentative back emitted power, otherwise get maximum transmission power when tentative back emitted power during less than the maximum transmission power of expection; The back emitted power emission signal of travelling carriage to determine.Wherein, maximum transmission power is based on the upper limit of the maximum and definite maximum transmission power of residence user content.This Poewr control method only adopts a kind of pattern to carry out transmitting power control, and relatively poor to the adaptability of complicated wireless channel environment, has influenced the raising of power system capacity and link-quality.
It is 5590409 United States Patent (USP) that name is called " transmit power controlling method and device ", application number, has proposed the method for transmission power of mobile station control in a kind of cdma communication system.Be the mean value of moving table measuring desired signal received signal power in the transmitting power control cycle, and the deviation of currency and last side value.If measured deviation surpasses the reference power deviation, then by the transmitting power of open Loop Power control setting corresponding to measured deviation, to reduce transmission power of mobile station fast; Otherwise, then determine transmitting power according to the power control bit word.This method has certain new meaning, but it does not do further processing when wireless channel environment is better, thereby will sacrifice a part of power system capacity.
Name is called 5896411 United States Patent (USP)s of " power of reverse link of enhancing property control in the wireless communication system ", has proposed a kind of enhancing mechanism of power of reverse link control, i.e. the power control step-size of dynamic adjustments reverse link.Wherein the adjusting of step-length is based on: the number of type of service, retroactive addition sign indicating number channel, base station total received power, the estimation of diversity gain, mobility requirement.This method has certain advance, but governing factor is too complicated, poor operability, and it is too frequent for the adjusting of power control step-size, will cause the unsteadiness of power control, influence the raising of systematic function and power system capacity, inaccessible system optimization.
In a word, existing Poewr control method is not ideal enough for the adaptive capacity of wireless communications environment, especially when wireless channel environment or communication link quality are relatively poor or better than system's expection level, the operability and the validity of existing power control mode are relatively poor, and power system capacity and communication performance are brought totally unfavorable influence.
Summary of the invention
The technical problem to be solved in the present invention is according to the wireless channel environment of code division multiple access system and communication link quality Dynamic Selection power control mode.By adopting corresponding power control mode, for because building blocks the shadow fading that brings or because the deep fading that the travelling carriage high-speed mobile causes carries out effectively power controls, both guaranteed systematic function and link-quality requirement, and don't be cost with the loss of power system capacity.Specifically, to provide the dynamic optimization method and the device of a kind of power control exactly, overcome that prior art exists poor such as control procedure complexity, operability, additional delay or capacitance loss are arranged, power system capacity or link-quality are had shortcomings such as adverse effect.
The above-mentioned technical problem of the present invention solves like this, construct a kind of dynamic optimization method that between travelling carriage and base station, carries out transmitting power control, may further comprise the steps: the up Initial Trans of travelling carriage (106) is set, or the down initial transmitting power of base station (102); Preset the decision threshold of the parameter that characterizes environment and communication link quality and change tolerance limit; Preset three kinds of power control modes that comprise normal mode, go up critical conduction mode and lower critical pattern; According to real-time detected described characterization parameter in the wireless channel of code division multiple access system, dynamically from three kinds of power control modes that preset, select corresponding a kind of power control mode operation.
In above-mentioned dynamic optimization method according to power control provided by the invention, the parameter of described sign environment and communication link quality is received signal to noise ratio SIR, and its decision threshold is SIRtarget, and it changes tolerance limit is Δ SIR.
In above-mentioned dynamic optimization method according to power control provided by the invention, the parameter of described sign environment and communication link quality can be the frame error rate (FER) of received signal, or the Block Error Rate (BLER) that calculates based on Cyclic Redundancy Check, also can be based on the received signal bit error rate (BER) of estimation, or by the determined performance evaluation index of other error tracking technology.
In above-mentioned dynamic optimization method according to power control provided by the invention, described normal mode is the control model that is near situation about changing the described decision threshold SIRtarget corresponding to measurement SIR, and the system that is applicable to moves under the wireless channel environment condition of expection or communication link quality is stabilized in the level that system expects; The described critical conduction mode of going up is to be higher than the control model that target gate is allowed excursion (SIRtarget+ Δ SIR) situation corresponding to measuring SIR, is applicable to that systematic function or link-quality are better than the level under the wireless channel conditions of expection; Described lower critical pattern is to be lower than the control model that target gate is allowed excursion (SIRtarget-Δ SIR) situation corresponding to measuring SIR, be applicable to that systematic function or link-quality are worse than the level under the wireless channel conditions of expection, wherein, the more described normal mode of described lower critical pattern has big slightly power to adjust step-length; The described more described normal mode of critical conduction mode of going up has big slightly power to adjust step-length.
In above-mentioned dynamic optimization method according to power control provided by the invention, described according to detected in real time described characterization parameter in the wireless channel of code division multiple access system, dynamically from three kinds of power control modes that preset, select corresponding a kind of power control mode operation, may further comprise the steps:, then adopt the transmitting power of lower critical pattern control travelling carriage or base station if base station measurement is lower than default mode switch thresholding (SIRtarget-Δ SIR) to SIR; If base station measurement is higher than mode switch tolerance limit (SIRtarget+ Δ SIR) to SIR, then adopt the transmitting power that goes up critical conduction mode control travelling carriage (or base station); When base station measurement is in the tolerance limit of system expectation to SIR within when (SIRtarget-Δ SIR is to SIRtarget+ Δ SIR), then the travelling carriage transmitting power that adopts normal mode to carry out corresponding travelling carriage or base station is controlled.
In above-mentioned dynamic optimization method according to power control provided by the invention, may further comprise the steps: by wireless network control layer (RNC) up link and down link are carried out open Loop Power control, control desired received signal quality thresholding and quality tolerance limit so that Initial Trans and inner loop power to be set; Finished the received signal quality of corresponding up link and down link respectively measures by base station and travelling carriage; According to the received signal quality measured value, base station and travelling carriage produce power control bit word (TPC) respectively in corresponding downstream frame and uplink frame; Suitable power control mode is selected in the corresponding TPC instruction of travelling carriage and base station receiving demodulation, carries out corresponding uplink and downlink transmitting power control.
In above-mentioned dynamic optimization method according to power control provided by the invention, may further comprise the steps: receiver is measured received signal SIR, the target gate SIRtarget and the tolerance limit Δ SIR that in the outer shroud power control process, set according to RNC, determine the relation of the measurement SIR of received signal with respect to the thresholding tolerance limit, if the SIR that measures is in the predetermined threshold variation scope (SIRtarget-Δ SIR is between SIRtarget+ Δ SIR), then corresponding transmitting station switches to normal mode and carries out power control, as this moment transmitter be in normal mode, then keep present mode; If the SIR that measures is lower than default threshold range (SIRtarget-Δ SIR), then corresponding travelling carriage switches to the lower critical pattern and carries out power control, if transmitter has been in the lower critical pattern, then keeps present mode; If the SIR that measures is higher than default threshold range (SIRtarget+ Δ SIR), then corresponding transmitter switches to critical conduction mode and carries out power control, if transmitter has been in critical conduction mode, then keeps present mode.
In above-mentioned dynamic optimization method according to power control provided by the invention, under described three kinds of patterns, carry out in the power control process, the transmitting power adjustment of base station or travelling carriage can be discrete or continually varying, described Discrete Change is meant each increase of receiving for receiver or the instruction that reduces transmitting power, transmitter is just regulated with predetermined step-length, handles accordingly up to the subsequent commands that receives power adjustments again; Described continuous variation is meant that receiver progressively adjusts its transmitting power, till receiving the order that stops power adjustments.
In above-mentioned dynamic optimization method according to power control provided by the invention, in critical conduction mode and the described lower critical pattern, described power adjustments amount is greater than the power adjustment under described normal mode on described.
In above-mentioned dynamic optimization method according to power control provided by the invention, described power control mode can switch like this, perhaps by the transmitter transmission power control message of base station (or travelling carriage) receiver to correspondence, command transmitter changes power control mode in needs; Perhaps provide measurement data and control information by base station (or travelling carriage) receiver to the transmitter of correspondence, corresponding transmitter is according to the measurement data judgement of receiving and select preferable power control mode.
In above-mentioned dynamic optimization method according to power control provided by the invention, described base station (or travelling carriage) sends message or the control command word notifies corresponding transmitter to select corresponding power control mode may further comprise the steps: 1) RNC is according to systematic function or communication link quality, carry out exterior ring power control, target gate SIRtarget is set and changes tolerance limit; 2) base station (or travelling carriage) receiver is measured SIR, and judges and measure the position of SIR with respect to the threshold variation scope, produces corresponding TPC bit in following/uplink frame emission; 3) base station (or travelling carriage) transmission message or control command word notify corresponding transmitter to select corresponding power control mode to finish transmission power adjustment: be in the threshold variation scope if promptly measure SIR, then normal mode is adopted in the transmitting power adjustment; Be higher than the threshold variation scope if measure SIR, then the transmitting power adjustment is adopted and is gone up critical conduction mode; Be lower than the threshold variation scope if measure SIR, then the lower critical pattern is adopted in the transmitting power adjustment.
In above-mentioned dynamic optimization method according to power control provided by the invention, described travelling carriage (or base station) receives relevant power control information and finishes the selection of self power control mode, may further comprise the steps: 1) RNC is dynamic according to systematic function or reception link-quality, carry out exterior ring power control, thresholding SIRtarget is set and changes tolerance limit; 2) base station (or travelling carriage) measures SIR, and judges and measure the position of SIR with respect to threshold range, produces corresponding TPC bit in following/uplink frame emission; 3) travelling carriage (or base station) receives above-mentioned information, and finishes the selection of self power control mode, carries out the corresponding transmission power adjustment simultaneously.Be in the threshold variation scope if promptly determine the SIR of the received signal that measures, then normal mode is adopted in the transmitting power adjustment; Be higher than the threshold variation scope if measure SIR, then adopt and go up critical conduction mode adjustment transmitting power; Be lower than the threshold variation scope if measure SIR, then adopt lower critical mode adjustment transmitting power.
Another technical problem of the present invention solves like this, construct a kind of dynamic optimization device of power control, form with the exterior ring power control device that is included in wireless network control unit by the inner loop power control device that is used for by power control dynamic optimization between air interface realization travelling carriage and base station, described inner loop power control device comprises the receiving element that is located in the described base station, transmitter unit, TPC command process unit, be used to carry out the sir measurement unit and the TPC generation unit of up link sir measurement, be located at the transmitter unit in the described travelling carriage, receiving element, input processing unit, transmitting power control model selected cell, TPC orders generation unit, be used to carry out the sir measurement unit of down link sir measurement, TPC command process unit, power control mode signal processing unit, described exterior ring power control device comprises and is used for being provided with the up Initial Trans of travelling carriage, or the down initial transmitting power of base station, and the device of the decision threshold SIRtarget of received signal to noise ratio SIR and variation tolerance limit Δ SIR thereof.
In above-mentioned dynamic optimization device according to power control provided by the invention, described base station is according to the comparison court verdict of described sir measurement unit SIR that measures and the threshold range of being set by described exterior ring power control device, produce power control word (TPC), be transmitted to travelling carriage in downlink frame, to carry out uplink power control; Described travelling carriage is transmitted to described base station in uplink frame and carries out descending power control according to the comparison court verdict generation power control word (TPC) of the SIR that is measured by described sir measurement unit with the threshold range of being set by described exterior ring power control device.
Implement the dynamic optimization method and the device of power control provided by the invention, adopt the power control of single-mode to compare with common, can adapt to the variation of wireless channel environment better, reasonably utilize limited power resource, promptly guarantee systematic function or link-quality in the complicated mobile wireless environment, optimize simultaneously each user's transmitting power again as far as possible, and not with the cost that is reduced to of power system capacity.When systematic function or link-quality deterioration, adopt the lower critical power control mode, compare with the common single power control mode that adopts of employing, it can make quality or performance evaluation index return to the normal level of expectation under the prerequisite that guarantees systematic function or link-quality in the short period of time; And when channel circumstance was better than the normal level of expection, critical power control model in the employing can be saved power consumption again, reduced the interference to other users, increased power system capacity, prolonged travelling carriage battery useful life simultaneously.
Description of drawings
Fig. 1 is for realizing the principle schematic of inner and outer ring power control;
Fig. 2 is for realizing the logic diagram of the dynamic optimization device that base station and transmission power of mobile station are controlled according to the present invention;
Fig. 3 is the schematic diagram that is used for illustrating three kinds of power control mode mechanisms of the inventive method;
Fig. 4 utilizes the inventive method to carry out the schematic flow sheet that power control dynamic optimization method carries out model selection;
Fig. 5 is in the inventive method, the schematic flow sheet of the transmitting power control under normal mode.
In conjunction with the accompanying drawings and embodiments, the inventive method and device are done further explaination and explanation, so that deeply understand target of the present invention, characteristic and advantage, part identical in the accompanying drawing adopts same numeral.
Embodiment
1 the present invention general introduction
Core concept of the present invention is the situation of change at link-quality or systematic function, reasonably select power control mode, with the transmitting power of travelling carriage in the dynamic optimization system or base station, promptly travelling carriage is according to the different conditions or the different different power control mode of selection that requires of systematic function or link-quality.If the SIR of base station measurement is lower than default mode switch thresholding, promptly relatively poor in the communication environment condition, (shielded when signal quality is more weak as travelling carriage signal in building, or signal is subjected to blocking of building and produces shadow effect, or operating mobile station is under than the atrocious weather condition), then adopt the transmitting power of lower critical pattern control travelling carriage (or base station), quickly recover to the normal level of system's expectation to guarantee base station measurement SIR or link-quality; If base station measurement SIR is higher than the mode switch tolerance limit, then adopt the transmitting power that goes up critical conduction mode control travelling carriage (or base station), avoid producing the power ramp phenomenon, guarantee power system capacity; And when base station measurement SIR was within the tolerance limit of system expectation, then travelling carriage adopted normal mode to carry out the transmitting power control of corresponding travelling carriage (or base station).The present invention adopts three kinds of power control modes:
1) normal mode: corresponding to measure the situation that SIR changes near thresholding SIRtarget.At this moment, system's operation or communication link quality under the wireless channel environment condition of expection is stabilized in the level of system expection;
2) go up critical conduction mode: be higher than the situation that target gate is allowed excursion (or target tolerance limit) corresponding to measuring SIR.At this moment, systematic function or link-quality are better than the level under the wireless channel conditions of expection, and wherein, last critical conduction mode has big slightly power to adjust step-length than normal mode;
3) lower critical pattern: be lower than the situation that target gate is allowed excursion (or target tolerance limit) corresponding to measuring SIR.At this moment, systematic function or link-quality are worse than the level under the wireless channel conditions of expection, and wherein: the lower critical pattern has big slightly power to adjust step-length than normal mode.
The method of the power control dynamic optimization that the present invention proposes may further comprise the steps or flow process:
1. wireless network control layer (RNC) carries out open Loop Power control to up link and down link, controls desired received signal quality thresholding and quality tolerance limit so that Initial Trans and inner loop power to be set;
2. base station and travelling carriage are finished the received signal quality measurement of corresponding up link and down link respectively;
3. according to the received signal quality measured value, base station and travelling carriage produce power control bit word (TPC) respectively in corresponding downstream frame and uplink frame;
4. suitable power control mode is selected in the corresponding TPC instruction of travelling carriage and base station receiving demodulation, carries out corresponding uplink and downlink transmitting power control.
Based on the above-mentioned transmitting power dynamic optimization method of the present invention, have following outstanding feature:
1. when the mobile radio channel environment is abominable, carry out power control owing to adopted special lower critical pattern, so than the conventional treatment mode, can reduce obviously that received signal quality worsens or received signal quality recovers the normal time, can the abominable wireless channel environment of fast adaptation;
2. when the mobile radio channel environment is better than the normal condition of expection, owing to adopted last critical conduction mode to carry out power control, so, can under the prerequisite that keeps normal system receptivity, reduce transmitter power as far as possible than normal mode, thereby the multiple access that reduces other travelling carriages disturbs, guarantee power system capacity, reduced the power consumption of transmitter simultaneously, prolonged battery useful life, reduce corresponding electromagnetic radiation, realized environmental protection.
Need to prove, do not need to keep critical conduction mode under the normal operating conditions and carry out power control.Because may make a small amount of minimizing of measuring SIR cause transmitting power significantly to increase like this, and excessive transmitting power adjustment can make measurement SIR surpass the excursion of thresholding, not only consume too much power resource, and in the limited cdma communication system of power limited, capacity, be extremely undesirable.
In view of the above, will further provide below and carry out power control mode and dynamically switch the systematic function of foundation or the evaluation method of communication link quality, and the selection of power control mode, and, the enforcement approach that the present invention is concrete is described in conjunction with example.
2 example environment
For ease of understanding, before specifically describing the present invention, earlier applied environment of the present invention is described.
The control of power that 3-G (Generation Three mobile communication system) relates to comprises/control of downlink outer loop power and on/descending inner loop power control, show based on complete power control flow such as Fig. 1 of the inventive method and device.Uplink power control wherein realizes the travelling carriage emitted power is controlled by means of the measurement of base station to up link; Descending power control realizes control to base station transmitting power by means of travelling carriage to the measurement of down link.
Exterior ring power is controlled at wireless network control unit (RNC) 110 to carry out, be mainly used to be provided with travelling carriage (UE) 106 up Initial Transs, or the down initial transmitting power of base station (NodeB) 102,104, and the decision threshold SIRtarget of received signal to noise ratio SIR and variation tolerance limit Δ SIR thereof.
The up link sir measurement is carried out in base station 102; Travelling carriage 106 is carried out the down link sir measurement.
Base station 102 produces power control word (TPC) according to the comparison court verdict of measuring SIR and threshold range and is transmitted to travelling carriage 106 in downlink frame, to carry out uplink power control; Travelling carriage 106 produces TPC according to the comparison court verdict of measuring SIR and threshold range and is transmitted to base station 102 in uplink frame, to carry out descending power control.
After mobile station receiver was handled by radio frequency/intermediate frequency converting unit 108, demodulation recovered the TPC instruction in base band receiving element 110.After the TPC instruction that the 112 pairs of travelling carriages in TPC command process unit receive is suitably handled, be used for controlling travelling carriage transmitter unit 118 power control mode in accordance with regulations and regulate transmitting power, send to then after intermediate frequency/radio frequency converting unit 120 is done respective handling, go out by air interface transmission; Processing and travelling carriage for base station receiver are basic identical.
According to the present invention, between travelling carriage (UE) and base station (Node B), realize the device of power control dynamic optimization, show as Fig. 2.Travelling carriage 106 and 102 inside, base station have a cover to receive unit 110,200 and transmitter unit 118,208 respectively; One cover sir measurement unit 114,204 is also arranged respectively, and TPC orders generation unit 116,206, TPC command process unit 112,202.Carry out radio communication by air interface (Uu) between UE and the NodeB.Sir measurement unit, TPC order generation unit, TPC command process unit, power control mode signal processing unit 126, the 124 common inner loop power controls that cooperate corresponding transceiver to finish Uplink/Downlink of transmitting power control model selected cell.
3 power control embodiment
The present invention has provided at different systematic functions or link-quality and has carried out the method that the dynamic power control model is switched, the wherein power control mode of Ti Chuing: normal mode, lower critical pattern and last critical conduction mode.The transition diagram 3 of several power control modes illustrates, and wherein transverse axis is represented the time, and SIR is measured in longitudinal axis representative.Diagram has provided measurement SIR curve 300 over time; The thresholding SIRtarget that on behalf of RNC, curve 304 dynamically arrange in the outer shroud power control process according to systematic function or link-quality; Curve 302 has provided RNC according to business demand and the systematic function or the link-quality requirement tolerance limit upper bound (SIRtarge+ Δ SIR) that set, that expect the thresholding SIRtarget under the normal operating conditions; Curve 306 has provided RNC according to business demand and systematic function or link-quality requirement tolerance limit lower bound (SIRtarge-Δ SIR) that set, that expect the thresholding SIRtarget under the normal operating conditions.
In the example that Fig. 3 provides, in initial a period of time, measure SIR and change in the scope that the thresholding SIRtarget of system's setting allows, so corresponding transmitting station is selected the power control under the normal mode, transmitter is regulated transmitting power with relative smaller step size; At T1 constantly, because the factor affecting such as deep fading on link obstructions or the propagation path, make that measuring SIR obviously descends, measure the excursion of allowing that SIR is lower than thresholding SIRtarget this moment, so corresponding transmitting station selects the lower critical pattern to carry out power control, owing to adopted big slightly adjustment step-length, after the time, measured the normal level that SIR returns to expectation at experience t0; Measuring T2 that SIR is higher than thresholding excursion that SIRtarget allows constantly, corresponding transmitting station switches to critical conduction mode to carry out power and controls, and is experiencing t1 after the time, and measurement SIR returns to the normal level of expectation.
As seen from Figure 3, normal mode is very suitable for measuring and carries out power control when SIR does a small amount of variation (Δ SIR) near thresholding SIRtarget; The lower critical pattern has a clear superiority in for the transmitting power control of handling (when being subjected to the bursty interference of blocking of building or other form as travelling carriage) under deep fading's condition; When last critical conduction mode is suitable for the processing channel environment usually the wireless channel environment condition is better,, reduce interference as far as possible, reduce power consumption, reduce electromagnetic radiation, prolong battery useful life other transmitting stations to reduce the transmitting power of corresponding transmitter as far as possible.
Power control mode switching flow such as Fig. 4 that the present invention proposes show.Receiver is measured received signal SIR, and the target gate SIRtarget and the tolerance limit Δ SIR that in the outer shroud power control process, set in conjunction with RNC, determine the relation of the measurement SIR of received signal with respect to the thresholding tolerance limit, this operation can irrespectively be carried out with the concrete power control mode of travelling carriage (or base station).Be in the predetermined threshold variation scope if measure SIR, then corresponding transmitting station switches to normal mode and carries out power control, as shown in Figure 5; If transmitter has been in normal mode, then keep present mode; Be lower than default threshold range if measure SIR, then corresponding travelling carriage switches to the lower critical pattern and carries out power control, if transmitter has been in the lower critical pattern, then keeps present mode; Be higher than default threshold range if measure SIR, then corresponding transmitter switches to critical conduction mode and carries out power control, has been in critical conduction mode as if transmitter, then keeps present mode.
The control of transmitting power mainly is whether the TPC numerical digit that receives by judgement is 1 ‖ 11 under the normal mode shown in Fig. 5, just increases transmitting power as "Yes", otherwise reduces transmitting power.
Obviously, at the particular communication environment, can adopt corresponding optimum thresholding or less than the threshold value of optimum thresholding.Above-mentioned thresholding is not a single numerical value, and is meant the measurement excursion that SIR allowed, promptly received signal can be in the tolerance limit.
Provide the embodiment of communication link quality or system performance evaluation below:
In one embodiment, systematic function or communication link quality evaluation are based on receiver and measure SIR.Change near expectation thresholding SIRtarget if measure SIR, then corresponding transmitting station adopts normal mode to carry out power control; Drop to the marginal range that is lower than thresholding SIRtarget if measure SIR, then adopt the lower critical pattern to carry out transmitting power control; Rise to the marginal range that is higher than thresholding SIRtarget if measure SIR, then adopting upward, critical conduction mode carries out transmitting power control.
In another example, the evaluation of systematic function is based on the erroneous level of received signal, promptly can be number of errors or error rate in continuous a period of time.Evaluation index can be the frame error rate (FER) of received signal, or the Block Error Rate (BLER) that calculates based on Cyclic Redundancy Check, also can be based on the received signal bit error rate (BER) of estimation, or by the determined performance evaluation index of other error tracking technology.Its concrete power control process is similar to the situation of utilizing SIR.
Provide the embodiment of transmission power adjustment under the different capacity control model below:
In one embodiment, transmitting power adjustment under the given pattern is a Discrete Change, i.e. each increase of receiving for receiver or the instruction that reduces transmitting power, transmitter is just regulated with predetermined step-length, handles accordingly up to the subsequent commands that receives power adjustments again.
In another embodiment, the transmitting power adjustment under the given pattern is carried out continuously, and promptly receiver is progressively adjusted its transmitting power, till receiving the order that stops power adjustments.
In above-mentioned two embodiment, last critical conduction mode and lower critical pattern all provide the power adjustment bigger than normal mode, and bigger power adjusting range promptly is provided in first embodiment, provide faster power to regulate the speed in a second embodiment.
Provide the embodiment that power control mode switches below:
In one embodiment, base station (or travelling carriage) receiver is to the transmitter transmission power control message of correspondence, and command transmitter changes power control mode in needs.
In another embodiment, base station (or travelling carriage) receiver provides measurement data and control information to the transmitter of correspondence, and corresponding transmitter is according to the measurement data judgement of receiving and select preferable power control mode.
Provide the embodiment of power control flow below:
In one embodiment, base station (or travelling carriage) sends message or the control command word notifies corresponding transmitter to select corresponding power control mode, and idiographic flow is as follows:
1.RNC according to systematic function or communication link quality, carry out exterior ring power control, target gate SIRtarget be set and change tolerance limit;
2. base station (or travelling carriage) receiver is measured SIR, and judges and measure the position of SIR with respect to the threshold variation scope, produces corresponding TPC bit in following/uplink frame emission;
3. base station (or travelling carriage) transmission message or control command word notify corresponding transmitter to select corresponding power control mode to finish transmission power adjustment.Be in the threshold variation scope if promptly measure SIR, then normal mode is adopted in the transmitting power adjustment; Be higher than the threshold variation scope if measure SIR, then the transmitting power adjustment is adopted and is gone up critical conduction mode; Be lower than the threshold variation scope if measure SIR, then the lower critical pattern is adopted in the transmitting power adjustment.
In another embodiment, travelling carriage (or base station) receives relevant power control information, and finishes the selection of self power control mode, and idiographic flow is as follows:
1.RNC dynamic according to systematic function or reception link-quality, carry out exterior ring power control, thresholding SIRtarget is set and changes tolerance limit;
2. base station (or travelling carriage) measures SIR, and judges and measure the position of SIR with respect to threshold range, produces corresponding TPC bit in following/uplink frame emission;
3. travelling carriage (or base station) receives above-mentioned information, and finishes the selection of self power control mode, carries out the corresponding transmission power adjustment simultaneously.Be in the threshold variation scope if promptly measure SIR, then normal mode is adopted in the transmitting power adjustment; Be higher than the threshold variation scope if measure SIR, then adopt and go up critical conduction mode adjustment transmitting power; Be lower than the threshold variation scope if measure SIR, then adopt lower critical mode adjustment transmitting power.
In the above-described embodiments, base station (or travelling carriage) receiver determine received signal quality be in, greater than or less than default threshold range.
More than by means of preferred embodiment the present invention is set forth, those skilled in the art can do various modification to the present invention under the prerequisite that does not deviate from spirit of the present invention.Spirit of the present invention and protection range are not subjected to the qualification of embodiment in the specification and are defined by the following claims.