CN1332545A - Effective closed-loop power control method for radio multimedia CDMA communication system - Google Patents

Abstract

The present invention includes the process of dividing the multiuser multimedia jobs of different transmission rate and different QoS requirement into several child job streams; channel multiple connection of the present invention to form closed-loop power control child channels of different QoS requirement; and performing cloed-loop power control to the child job streams. Adopting the closed-loop power control of the present invention multimedia CDMA communication system can meet the requirement of the multimedia jobs in different transmission rates and different QoS while minimizing emitted power and interference and increasing system capacity.

Description

Effective closed-loop power control method for radio multimedia CDMA communication system

(1) technical field:

The invention belongs to radio multimedium code division multiple access (CDMA) moving communicating field, relate in particular to effective closed-loop power control method.

(2) background technology:

Following mobile radio system is with multimedia services such as support voice, data, image and videos, because cdma communication system has big power system capacity, good anti-multipath and antijamming capability, can support characteristics such as multimedia service transmission easily, become the major technique of 3G (Third Generation) Moblie.The capacity of frequency division multiple access and TDMA communication system is a limited bandwidth, and the capacity of cdma system then only is interference-limited, reduces and disturbs the message capacity that can directly increase CDMA mobile communication system.In the cdma cellular mobile communication system, because the frequency recycling can form the interference of minizone in the cellular system, the travelling carriage that is positioned at the cell edge place will be subjected to big interference, and this phenomenon is commonly called " edge problem "; Because the decline of wireless channel and travelling carriage are different with distance between the base station, the high power signal user that the base station receives causes very big interference to weak power signal user, make weak power signal user's decreased performance, even cisco unity malfunction, this just is called as " near-far interference ".

Power control is to adopt in the CDMA mobile communication system of correlation reception technology to overcome " edge problem " and " near-far interference ", thereby improves the effective ways of power system capacity.

In addition, required being maintained in of service quality (QoS) of the foundation of communication link and user depends on power control techniques to a great extent in the CDMA mobile communication system.

Power control techniques is exactly the transmitting power of control transmitting terminal, reduces the interference of minizone, and the decline of compensation wireless channel makes CDMA mobile communication system have following advantage:

(1) power consumption minimum, the life-span of prolongation travelling carriage battery;

(2) reduce interference, maximized system capacity;

(3) guarantee that the QoS of communication link requirement is to support the multimedia service to the QoS sensitivity;

(4) provide the load bridging between unequal loaded cell in the service area.

In the mobile radio system that only has a kind of business, all business have identical communication link quality requirement, therefore, in the CDMA mobile communication system of single business, adopted Poewr control method based on signal to noise ratio (SIR) balance, it is to make all communication links reach identical SIR, and like this, system can reach the SIR that maximum can reach, and its convergence property is good.But it has following problem:

(1) value of the SIR that each communication link finally reaches in the system may be lower than threshold value;

(2) SIR of all communication links is identical, and this just means that this communication system can not make and has difference

The multimedia service that SIR requires exists simultaneously.

In the radio multimedium mobile communication system, exist business with different transmission rates and different SIR requirements, this power that just causes the power in the wideband multimedia CDMA mobile communication system to be controlled in the cdma system that will be different from the single business in arrowband is controlled, that is to say, concerning the radio multimedium mobile communication system, its power control is not only at the user, also must carry out at different business.Poewr control method based on the SIR balance no longer is suitable for the WCDMA cell mobile communication systems, therefore, is necessary to seek the new Poewr control method that is suitable for the WCDMA mobile communication system.

Power control in the radio multimedium mobile communication system is carried out physical channel, should consider such fact, although the user need provide multimedia service in the WCDMA cell mobile communication systems, but a DPCH can not be provided for every kind of business of a certain user, remain to each user a DPCH is provided.In present WCDMA agreement, the cycle of closed power control is 1500Hz, promptly each time slot once, for this reason, defining each time slot is a closed power control subchannel cycle.That is to say that closed power control carries out a power control sub-channel.With 12.2kbps voice+64Kbps data+3.4kbps signaling is example, and the closed power control subchannel that the 10ms physical frame that the subservice that this user's different QoS requires forms after the multiple connection of process channel and each physical frame comprise as shown in Figure 1.

From Fig. 1 we as can be seen, in closed power control subchannel, have 3 kinds of different business to exist simultaneously, and minimum closed power control unit is the cycle of a power control sub-channel, i.e. closed power control is that each time slot carries out once.Like this, in order to guarantee that the error rate (BER) requires little performance of services, in a power control sub-channel, the control of transmitting power must be undertaken by the minimum business of BER requirement, like this, the business of BER less demanding (be BER can than higher) is caused the waste of transmitting power, simultaneously, interference to other user has also unnecessarily increased, and causes the decline of power system capacity.

In order be effectively to carry out power control,, minimize transmitting power simultaneously and to other user's interference, we propose technical scheme of the present invention to guarantee that different business can reach different qos requirements to different business in the WCDMA mobile communication.

(3) summary of the invention:

We are divided into different subservice stream with each user's different transmission rates with the multimedia service that different QoS requires, after the present invention's channel multiple connections that propose, different with existing protocol, form the closed power control subchannel that different QoS requires subservice, again each subservice stream is carried out closed power control.Like this, in the multimedia CDMA mobile communication system that adopts the correlation reception technology, employing requires the closed power control of subservice based on different QoS of the present invention, can guarantee that multimedia service has the requirement of different transmission rates and different QoS, simultaneously, minimize transmitting power and, increase power system capacity other user's interference.

Figure 2 shows that based on close-loop power controlling method flow chart in the multimedia CDMA mobile communication system of different QoS requirement subservice power control sub-channel.

At transmitting terminal, at first multimedia service is divided into different information flows, as the voice subservice among Fig. 2, data subservice or the like, each information flow all has the QoS of its requirement.The subservice that each different QoS requires is carried out different chnnel codings respectively, the bit of the miscellaneous service after will encoding again interweaves respectively, the purpose that interweaves provides the time diversity gain, the subservice that different QoS after interweaving requires is carried out rate-matched again, and the purpose of rate-matched is that the bit number with different subservices is adapted to and meets next step and carry out the fixed number of bits that the physical channel multiple connection requires.Afterwards, these business are carried out priority queueing by different qos requirements, the business that needs real-time Transmission (for example: voice, video etc.) having the highest priority, secondly is the low business of requirement BER, and their priority is only second to real time business, secondly be that BER is required not too high business again, and the insensitive service priority of time delay is minimum, because can wait other method to reduce its BER by re-transmission to the insensitive business of time delay, improves performance.To carry out channel multiple connection (formation of 10ms physical frame) through the subservice data flow that the different QoS after the priority queueing requires, with the variety classes business according to priority order be connected in series successively, form continuous data flow and transmit.If the user has only a kind of high-priority service, for example, professional 1 has high priority, and professional 2 and professional 3 priority is lower, and when these professional amount of bits are big (greater than 1 10ms physics frame length), we with these multimedia services according to priority order, be connected in series by frame length (10ms), at this moment, have only a kind of business in the 10ms physical frame, shown in Fig. 3 (a), obviously, at this moment, has only a kind of business in the closed power control subchannel.If the business that priority is high has two, professional 1 and professional 2, and the amount of bits of these two kinds of business is connected in series with regard to the mode by Fig. 3 (b) when all bigger (greater than 1 10ms physics frame length), is the cycle with two kinds of business with a 10ms physical frame, alternately serial connection, transmission.When traffic carrying capacity less than one frame, the subservice that the different QoS in the frame requires should be that unit is connected in series to form the 10ms physical frame with the time slot by the method shown in Fig. 3 (c).

After carrying out above-mentioned three kinds of channel multiple connections, just can carry out the closed power control based on the professional closed power control of different QoS subchannel of up link in the radio multimedia CDMA mobile communication system as shown in Figure 2.Under the process of this closed power control:

At first multimedia service QoS as requested is divided into different subservice stream, the subservice flow point that these are different does not carry out chnnel coding, interweaves, rate-matched, form the power control sub-channel data flow that different QoS requires according to channel multiple connection method proposed by the invention again, these data flow are carried out the spread spectrum of different spreading factors, the selection of spreading factor SF is such, in addition R _iSF _i=R _jSF _j=R _Chip, R wherein _iThe speed of expression subservice i, R _ChipBe the spread symbols speed of system's regulation, digital signal behind the spread spectrum is given power amplification unit through behind the D/A switch, this power amplifier is controlled by closed loop power control command simultaneously, just launches by antenna through the signal after the purpose of closed loop transmit power control.After the base station receiving terminal receives signal, carry out matched filtering at first to received signal, obtain wanting demodulation user's useful signal, another effect of matched filter can be come out the Signal Separation that time delay is come greater than the different paths of a symbol width exactly in the CDMA mobile communication system, the signal that these different paths are come is given the RAKE combiner and be concerned with after the merging, can improve the reception SIR of receiving end signal, thus the systematic function of providing.The signal that comes out from the RAKE combiner will be given channel and separate the anti-process that multiplexer carries out the channel multiple connection method that the present invention proposes, thereby the subservice that different QoS requires is separated, process is separated the subservice that the two-way different QoS after the channel multiple connection requires, one the tunnel gives deinterleaver deinterleaves, carry out the subservice stream that channel decoding requires with the different QoS that recovers transmission again, the subservice data flow that another road different QoS requires is sent to the sir measurement device, so that carry out the reception sir measurement that different QoS requires subservice, give comparator with measurement result, compare with the target SIR value, give closed loop power control command with comparative result and form device, form power control command, if comparative result is to measure SIR＞target SIR, closed loop power control command forms the just power control command of output " 0 " of device, otherwise, then export the power control command of " 1 ".The channel multiplexor that this power control command that is used for the control of uplink closed loop power is given the base station transmitting terminal, power control command has inserted physical channel with regard to form in accordance with regulations, uplink physical channel through base station transmitting terminal spread spectrum after, give the analog to digital signal conversion module of base station transmitting terminal, at last, this signal is launched through after the power amplification.After the travelling carriage receiving terminal receives signal, carry out matched filtering at first to received signal, obtain wanting demodulation user's useful signal, give the merging that is concerned with of RAKE combiner.The signal that comes out from the RAKE combiner will be given channel and separate multiplexer and carry out channel and separate multiple connection, extract the up-link power control bit after, give the controlled power amplifier of travelling carriage user's transmitting power adjusted.So far, just finished the effective purpose of closed loop transmit power control procedure that the present invention proposes based on different QoS service power control subchannel.

After carrying out the closed power control based on the professional closed power control of different QoS subchannel of above-mentioned up link, the adjustment of transmitting power is each time all only carried out a kind of business, thereby, can when reaching the QoS of different business requirement, minimize transmitting power.Below, just the result with Computer Simulation illustrates beneficial effect of the present invention:

We suppose N co-channel cells in the WCDMA cell mobile communication systems, in each sub-district M is arranged _n(n=1,2 ... N) individual multimedia terminal, total Q multimedia terminal in the system

Each multimedia terminal can provide K kind business at most.

Be convenient and analyze, we with every bit signal energy of receiving terminal and the ratio of interference (

) be used as the criterion of communication link quality.After having adopted the power control sub-channel formation method that we propose, in a closed power control cycle, each user only provides a kind of in the K kind business, therefore, at a certain power control period, concerning up link, the base station receives m user's in n the sub-district For: ${\left(\frac{E_b}{I_o}\right)}_g\underset{=}{\mathrm{\Δ}}{\mathrm{\Γ}}_g^w=\frac{G_{\mathrm{gn}}{P}_g}{\underset{j\≠g}{\overset{Q}{\mathrm{\Σ}}}{G}_{\mathrm{jn}}{P}_j+\mathrm{\η}}\•\frac{B}{P_g}=\frac{P_g}{\underset{j=1}{\overset{Q}{\mathrm{\Σ}}}{W}_{\mathrm{gi}}{P}_j+\mathrm{\η}/{\mathrm{SF}}_g{G}_{\mathrm{gn}}},n=\mathrm{1,2}\…N$ Wherein, g is not an independent variable, and it is not only relevant with the numbering of sub-district, and is also relevant with Customs Assigned Number, can be expressed as: $g=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{M}_{i-1}+m,$ n＝1，2，…，N，M ₀＝0。p _gBe the transmitting power of user g, B is a system bandwidth, R _gBe the transmission rate of a certain power control period user g, G _GnBe the link gain between the base station among user g and the sub-district n, η is that bilateral power spectral density is

Additive white Gaussian noise.With the up link is example, in order to guarantee the communication link transmission quality of each customer requirements, at some power control periods, requires following formula to set up: ${\mathrm{\Γ}}_g^w\≥{\mathrm{\γ}}_g^w$ In the formula, γ _g ^wIt is the desired communication link transmission quality of user g threshold value in a certain power control period.

Write for convenience, we are write (2) formula as following matrix form: (I-γ _W ^W) P 〉=u here, I is the unit matrix of Q * Q,

Be the column vector of the communication link transmission quality threshold value of each customer requirements in a certain power control period, P=(p ₁, p ₂..., P _g) ^T, P＞0th, the column vector of user emission power,

It is the column vector of normalized noise power.

In order to prove beneficial effect of the present invention, we have carried out emulation.Simulated conditions are as follows: the topological structure of WCDMA mobile communication system is favose.N=19, Q=1900, the number of users in each sub-district is identical, and the user evenly distributes in the sub-district, have four kinds of business in the system, their transmission rate is respectively the 8Kbps speech business, the 64Kbps video, the 32Kbps data service, the 128Kbps file, the ratio of quantity is 4: 2: 2: 2.The specific performance index request is as shown in table 1.

The parameter of table 1 simulation usefulness

We represent different types of business with equivalent professional number, and promptly speed is that the service definition of 8Kbps is a basic service, and the professional equivalence of 64Kbps speed is 8 basic services, and the like.Suppose that speech business has limit priority, video secondly, other two kinds of business are low priorities, system bandwidth is 5MHz, and link gain adopts following form: $G_{\mathrm{gi}}=\frac{A_{\mathrm{gj}}}{d_{\mathrm{gj}}^{\mathrm{\ρ}}}$ In the formula, A _GjBe decay factor, the power fluctuation that expression is caused by decline, we only consider that average is 0, variance is the lognormal shadow fading of 6dB, d _GjBe the distance between the base station among portable terminal g and the sub-district j, ρ represents the propagation loss factor, and we get ρ=4.Through 100000 simulations, the analog result that obtains as shown in Figure 3 and Figure 4.

As can be seen from Figure 3, when carrying out closed power control with existing power control sub-channel, the professional average error rate of all that obtain is identical, and, increase along with the increase of number of services, do not reach the requirement that multimedia service has different link transmission quality, video traffic is the business with high priority, the transmission quality of its requirement must be met, but in equivalent traffic carrying capacity greater than 156 o'clock, the service quality that its requires is not being met.And adopt power control sub-channel proposed by the invention to carry out closed power when control, different business can obtain needed separately different average error rate characteristic, even when traffic carrying capacity is big (equivalent traffic carrying capacity was greater than 200 o'clock), the average error rate performance of the business that priority is high also can be guaranteed.It can be said that brightly, adopt power control sub-channel proposed by the invention to carry out closed power when control, gross power that can the minimum user transmitter, thus increase power system capacity.

(4) description of drawings:

Fig. 1 is the channel multiple connection schematic diagram that adopts in the prior art WCDMA standard;

Fig. 2 is the uplink closed loop Poewr control method flow chart based on different QoS requirement subservice closed power control subchannel that the present invention proposes;

Fig. 3 requires subservice to carry out forming the schematic diagram that different QoS requires subservice closed power control subchannel after the channel multiple connection with the different QoS that the present invention proposes;

Fig. 4 be adopt that the present invention proposes based on different business closed power control subchannel the time carry out the performance map that the miscellaneous service after the closed power control can reach;

Fig. 5 adopts prior art WCDMA standard closed power control subchannel to carry out the performance map that the miscellaneous service after closed power is controlled can reach.

(5) specific embodiment:

What Fig. 2 described is that employing is of the present invention based on different QoS requirement subservice close-loop power control subchannel Carry out the enforcement figure of Reverse Link Close Loop Power Control in the CDMA multimedia mobile communication system. We are many The business that media termination provides is divided into a plurality of information flows, and each information flow has its quality of service requirement, The close-loop power control subchannel formation method (Fig. 3) that proposes according to the present invention again, the formation frame length is 10ms Physical channel. Like this, in each close-loop power control subchannel, only have a kind of business, and, difference The business of qos requirement can not appear in the same close-loop power control subchannel, just high BER can not occur The phenomenon of the subservice transmitting power waste that requires reduces the interference to other user simultaneously, and the increase system holds Amount.

Among the figure, 101 modules are channel encoders of user side, and the different QoS that it comes the multimedia terminal is wanted The sub data flow of asking carries out different chnnel codings. 102 modules are interleavers of user side, and its effect just That source bits with different subservices was distributed in the different time periods, in order to deep fade occurs or burst is done When disturbing, can not disturbed simultaneously from a certain most important code bit in the source bits. 103 modules are speed Rate adaptation, its effect are that different business is become to be fit to physical frame through the Data Matching after the chnnel coding Bit number. 104 modules are 10ms physical frame shapers, the merit as shown in Figure 3 that it proposes according to the present invention Rate control subchannel formation method is carried out the 10ms physical frame and is formed. 105 modules are spread spectrum module, to not of the same trade or business The physical sub-channels of being engaged in is carried out the spread spectrum of different spreading gains. Signal behind the spread spectrum is given 106 modules, 106 Module is that data signal is to the converter of analog signal. 107 modules are controlled power amplifiers, are subjected to up Its transmitting power is adjusted in the control of link closed loop power control command. 108 modules are transmitting antennas of user side.

The signal that the user sends reaches base station receiving terminal Anneta module 109 modules through radio transmission. 110 moulds Piece is the matched filter module of base station receiving terminal, and its effect is to carry out to the received signal matched filtering, Obtain the signal of needs. The 111-1 module is the RAKE merging module for data demodulates, and its effect is Multipath signal is merged, to improve the signal to noise ratio of receiving terminal. The 111-2 module is for sir measurement RAKE merges module. 112 modules are channel solution multiple connection modules, its effect be with different subservices by According to the operation opposite with the multiple connection method shown in 104 modules different business is separated. 113 modules are to separating multiple connection After different subservice signals carry out respectively deinterleaving. 114 modules are sir measurement modules, and it will be with time slot For chronomere merge to conciliate the SIR that different subservice signals after the multiple connection carry out different subservices to RAKE Measure, obtain measuring SIR. 115 modules are channel decoding modules, its different subservices letter after to deinterleaving After number deciphering, just can recover the signal that the customer multi-media terminal sends. 116 modules are that BER surveys Amount module, base station, provide by exterior ring power control according to the BER of each the user's different business that measures The target SIR value that close-loop power control is used. 117 modules are comparators, and it is with target SIR and measurement The SIR that obtains compares, and gives 118 modules with comparative result. 118 modules are close-loop power control lives Order forms module, if comparative result is to measure SIR＞target SIR, 119 modules are the power of output " 0 " just Control command, otherwise, the power control command of " 1 " then exported. This is used for the control of uplink closed loop power Power control command give 122 modules, 112 modules are that the 10ms physical frame of base station forms module, power Control command form in accordance with regulations inserts physical channel. Uplink physical channel through base station transmitting terminal spread spectrum module-Behind the 123 module spread spectrums, give 124 modules. 124 modules are analog to digital signal conversions of base station transmitting terminal Module, effect is with 106 modules. 125 modules are power amplifiers of base station transmitting terminal, and it is with analog signal Carry out giving base station transmit antennas 126 after the power amplification, carry out wireless transmission. 127 modules are connecing of user side Receive antenna, 128 modules are travelling carriage receiving terminal matched filters. 129 modules are RAKE of travelling carriage receiving terminal Merge module. The effect of the effect of these two modules and 110 modules and 111 modules is similar. 130 modules are Channel solution multiple connection module in the travelling carriage, the effect of this module are that the subservice branch that different QoS requires is come. 131 modules are up-link power control bit extraction modules in the travelling carriage, and the effect of this module is to extract Power control bit on the assigned position that the base station sends, and give 107 with the power control bit that extracts Module is carried out the adjustment of travelling carriage purpose of closed loop transmit power. So far, just finished the CDMA multimedia mobile communication The close-loop power control process of up-link in the system.

Claims (5)

1, effective closed-loop power control method for radio multimedia CDMA communication system.It is characterized in that carrying out according to the following steps: multimedia service is divided into the sub data flow that different QoS requires, the subservice that each different QoS requires is carried out different chnnel codings respectively, the bit of the miscellaneous service after will encoding again interweaves respectively, the subservice that different QoS after interweaving requires is carried out rate-matched more respectively, these are carried out priority queueing through the subservice after the rate-matched by different QoS, form the power control sub-channel that different QoS requires, then, carry out effective purpose of closed loop transmit power control.

2, effective closed-loop power control method for radio multimedia CDMA communication system as claimed in claim 1, it is characterized in that the subservice that different QoS requires is carried out priority queueing, to the business that needs real-time Transmission (for example: voice, video etc.) has the highest priority, next is the low business of requirement BER, their priority is only second to real time business, secondly be that BER is required not too high business again, and the insensitive service priority of time delay is minimum, because can wait other method to reduce BER by re-transmission to the BER of the insensitive business of time delay.

3, effective closed-loop power control method for radio multimedia CDMA communication system as claimed in claim 2, after it is characterized in that the subservice that different QoS requires carried out priority queueing, the variety classes business is carried out channel multiple connection (formation of 10ms physical frame) according to the priority order serial connection in chronological order, form the subservice data flow that different QoS requires.

4, effective closed-loop power control method for radio multimedia CDMA communication system as claimed in claim 1 is characterized in that the subservice that different QoS requires is carried out respectively the spread spectrum of different spreading factors, and the principle that spreading factor is selected is R _iSF _i=R _jS _j=R _Chip, R wherein _iThe speed of expression subservice i, R _ChipBe the spread symbols speed of system's regulation.

5, effective closed-loop power control method for radio multimedia CDMA communication system as claimed in claim 1, be characterised in that in each closed power control subchannel and have only a kind of business, and, the business that different QoS requires can not appear in the same closed power control subchannel, the phenomenon that the subservice transmitting power waste of high BER requirement just can not occur, reduce interference simultaneously, increase power system capacity other user.

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