CN1607756A - Determination method for confirmed or unconfirmed bits in high-speed special-purpose physical control channels - Google Patents

Abstract

This invention discloses a judgment method for confirming or non-confirming a bit value in special physical control channels so as to satisfy the minimum error probability judgment under interfering and canceling multi-user test to generate the optimum signals to guarantee its performance at the same time when satisfying the maximum down stream HSDPA data through put including: receiving ten continuously transmitted confirmed or non-confirmed bit signals to be laminated, computing the first and second threshold values based on the channel decline parameter, judging said confirmed or non-confirmed bit values by a judgment formula according to the laminated signal value and said first and second threshold values.

Description

Confirm in the High-Speed Dedicated Physical Control Channel or the decision method of acknowledgement bit not

Technical field

The present invention relates in the broadband CDMA system, the high-speed downstream bag inserts the decision method of high speed Dedicated Physical Control Channel, be particularly related under the interference cancellation Multiuser Detection, confirm or do not confirm the decision method of (ACK/NACK) bit in the High-Speed Dedicated Physical Control Channel.

Background technology

Wideband Code Division Multiple Access (WCDMA) (Wideband Code Division Multiple Access, be called for short " WCDMA ") system owing to its strong multimedia communication capacity, high-speed data transmission speed and efficiently many advantages such as the availability of frequency spectrum gain great popularity, and become the developing goal of future mobile communications.Yet the development has no limits for technology, and mobile multimedia communication demand that rises and more and more nervous Radio Resource have also proposed more and more higher requirement to the performance of WCDMA system rapidly.Constantly studying the new technology that obtains is applied in the WCDMA system, further improved the various aspects of performance of WCDMA, such as Multiuser Detection (Multiple User Detection, abbreviation " MUD ") technology, high-speed downstream bag access (High Speed Downlink Packet Access is called for short " HSDPA ") etc.

MUD is the key technology that overcomes interference in the WCDMA system, is a kind of Enhanced Technology that improves power system capacity, coverage and performance.Practical application MUD technology mainly is the interference cancellation method at present, the interference cancellation method is considered as useful signal with the signal of desired user, other users' signal is considered as interference signal, from received signal, eliminate earlier other users' interference according to regenerated signal, obtain the signal of desired user, signal to desired user detects then, thereby improves the performance of system.

HSDPA is the standardized partnership projects of 3G (Third Generation) Moblie (the 3rd GenerationPartnership Project, being called for short " 3GPP ") the asymmetric demand of up-downgoing data service puts forward in order to satisfy in Release 5 agreements, it can make the highest downstream data rate reach 10Mbps, thereby improve user's downstream data traffic speed greatly, and do not change the network configuration of the WCDMA system that has built.This technology is a kind of important technology that the WCDMA networking later stage improves downlink capacity and data service rate.The key technology that HSDPA adopts is Adaptive Modulation and Coding (AdaptiveModulation Coding is called for short " AMC ") and mixes automatically and repeat (Hybrid ARQ is called for short " HARQ ").The HSDPA technology has increased high speed descending sharing channel (High Speed DownlinkShared Channel is called for short " HS-DSCH "), and relies on HARQ and AMC that channel variation is adapted to.Different users divides shared HS-DSCH channel in time-division and sign indicating number; For the bearing downlink signaling, also increased shared control channel (High Speed Shared Control Channel, be called for short " HS-SCCH "), the up employing High-Speed Dedicated Physical Control Channel relevant (HighSpeed Dedicated Physic Control Channel with HS-DSCH, be called for short " HS-DPCCH "), carrying UE is to the feedback information of the HS-DSCH channel data that receives, comprise: confirm or do not confirm (ACK/NACK) bit information and channel quality indication (Channel Quality Indication is called for short " CQI ") information.

HS-DSCH has adopted three basic fundamentals on the basis that channel transmission parameters can be adjusted real-time: rapid link adaptation technique, the automatic retransmission technique of rapid mixing and HS-DSCH channel fast dispatch technology.This channel is mainly used in the transmission of high speed packet data.HS-DSCH can be shared by a plurality of users in time-domain, and HS-DSCH uses for unit distributes to the user with Transmission Time Interval (Transmission Time Interval is called for short " TTI ").In order to reduce time delay, the granularity dynamics that increases dispatching process and the feature of following the tracks of time-variant wireless channel more in time, HS-DSCH has adopted the TTI of 2ms, and that current WCDMA employing is 10ms.

HSDPA sends high speed packet to UE by descending HS-DSCH channel, and realizes the coordination that the HSDPA downlink data sends and receives by descending HS-SCCH channel between BS and UE.UE deciphers packet after receiving packet, and according to decode results and down channel quality test result, sends ACK/NACK and CQI by up HS-DPCCH channel.When packet is deciphered when correct, UE sends ACK information to BS, makes BS then send next packet; If packet decoding error, UE send nack message to this BS, make BS retransmit this packet.

Channel quality information characterizes with the CQI bit, and the CQI bit sends to BS after encoding, and BS obtains the CQI bit by decoding, and carries out AMC control with the CQI bit, adjusts the code modulation mode of descending HS-DSCH.When CQI showed that down channel quality is better, BS can adopt the respective coding modulation system, increased data transmission rate; Otherwise, then, reducing data transmission rate by the change code modulation mode, AMC strengthens the property and the key technology of flexibility.After BS has sent packet to UE, can receive this UE feedack and CQI information at corresponding ascending time slot according to the certain time sequence relation.

In above-mentioned HSDPA technology, the judgement of up HS-DPCCH channel ACK/NACK bit is very important.BS descending sent packet to the user after, just receive the feedback information of this user HS-DPCCH channel in the corresponding time.If the court verdict to HS-DPCCH channel received signal is: the UE feedback information is ACK, and then BS just then sends next packet; If the court verdict to HS-DPCCH channel received signal is: the UE feedback information is NACK, and then BS just follows the retransmission data bag.If the court verdict to HS-DPCCH channel received signal is: HS-DPCCH channel no signal, then the information of BS HS-DPCCH transmission at this moment is designated as discontinuous emission (DiscontinueTransmission, be called for short " DTX "), the value of DTX is 0, and BS also has corresponding processing method to such court verdict.

For BS, the ACK/NACK bit that the HS-DPCCH channel sends may be got three value: ACK, NACK and DTX.Require the error rate of HS-DPCCH channel ACK/NACK bit to satisfy following requirement in the HSDPA related protocol:

P{DTX--＞ACK}＜10-2, i.e. DTX mistaken verdict is that the probability of ACK is less than 10-2;

P{ACK--＞NACK}＜10-2; Be that the ACK mistaken verdict is that the probability of NACK is less than 10-2;

P{NACK--＞ACK}＜10-4; Be that the NACK mistaken verdict is that the probability of ACK is less than 10-4;

The decision method that existing technology adopts is based on all that above three formulas obtain, and comprises following steps:

Earlier find the solution judging threshold according to the posterior probability values of above-mentioned three formulas;

Judge the signal that receives according to judging threshold again.

In actual applications, there is following problem in such scheme: as previously mentioned, when the MUD technology was applied in the BS system, BS adopted the interference cancellation multi-user test method, before every grade of interference cancellation, all needs to obtain each user's regenerated signal.User's regenerated signal is accurate more, and the Multiuser Detection performance is just good more.And the decision method that satisfies above-mentioned three formulas can not guarantee that this judgement is the maximum a posteriori probability decision method, can not guarantee that promptly judgement is the minimum error probability judgement, the regenerated signal that is obtained by such court verdict is not best regenerated signal, directly influences the quality of other subscriber signals.This will cause interference cancellation method reliability decrease, and the error rate raises on the contrary, and systematic function descends.

Cause a main cause of this situation to be, the decision method of employing can not guarantee the minimum error probability judgement.

Summary of the invention

The technical problem to be solved in the present invention provides in a kind of High-Speed Dedicated Physical Control Channel to be confirmed or the decision method of acknowledgement bit not, make and under the interference cancellation Multiuser Detection, satisfy the minimum error probability judgement, the generation subscriber signal is an optimum signal, can guarantee the performance of interference cancellation Multiuser Detection when satisfying descending HSDPA data throughout maximum.

In order to solve the problems of the technologies described above, the invention provides in a kind of High-Speed Dedicated Physical Control Channel and to confirm or the decision method of acknowledgement bit not, comprise following steps:

Ten of receiving that described High-Speed Dedicated Physical Control Channel transmits continuously of A confirm or acknowledgement bit signal not, and stack;

B calculates first and second threshold values according to channel fading parameters;

Signal value and described first and second threshold values of C after according to described stack are adjudicated the described affirmation or the value of acknowledgement bit not by the judgement formula.

Wherein, described affirmation or not the value of acknowledgement bit comprise affirmation, do not confirm and three kinds of states of discontinuous transmission.

In the described steps A, confirm or not acknowledgement bit signal and stack for ten that receive the continuous transmission of described High-Speed Dedicated Physical Control Channel.

Described affirmation or not the judgement formula of acknowledgement bit be:

Wherein, d is the court verdict value, and Y is the signal value after the described stack, T ₁, T ₂Be described first and second threshold values, court verdict value-1 represent the affirmation state ,+1 the representative do not confirm state, 0 the representative discontinuous transmit status.

The computing formula of described two threshold values is:

$T_1=-\frac{A_{\mathrm{ACK}}}{2};$ $T_2=\frac{A_{\mathrm{NACK}}}{2};$

Wherein, T ₁, T ₂Be described two threshold values, A _ACKFor send when user terminal be acknowledgement bit the time property the taken advantage of decline distortion factor that causes by channel fading and power bias, A _NACKFor what send when user terminal is the property the taken advantage of decline distortion factor that is not caused by channel fading and power bias during acknowledgement bit.

By relatively finding, technical scheme difference with the prior art of the present invention is, determine judging threshold according to channel fading situation and signal acceptance method, realize confirming or the not minimum mistake in judgment probability judgement of acknowledgement bit information, and court verdict is used for the interference cancellation Multiuser Detection.

Difference on this technical scheme, brought comparatively significantly beneficial effect, make that promptly the regeneration subscriber signal of interference cancellation Multiuser Detection is an optimum signal, guaranteed the performance of Multiuser Detection, under the prerequisite of using multiuser detection, guarantee the communication quality of HS-DPCCH channel, realize the high-throughput of HSDPA system, improve the data transfer rate of cell mobile communication systems, more flexible net capacity is provided.

Description of drawings

The affirmation of Fig. 1 High-Speed Dedicated Physical Control Channel according to an embodiment of the invention or do not confirm the decision method flow chart of (ACK/NACK) bit.

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.

Suppose that BS adopts the RAKE reception technique at the HS-DPCCH channel from the receiving terminal that UE receives, in RAKE receiver, comprise a plurality of correlators, each correlator all with the multipath signal branch synchronised that receives, final gained signal should be the combination of mulitpath signal.Therefore the ACK/NACK bit of the HS-DPCCH that sends of UE, through the BPSK modulation, this bit value be-1 (ACK) ,+1 (NACK) or 0 (DTX), the process wireless channel is received by RAKE receiver at BS, the signal indication that demodulation obtains is:

Formula one Y (m)=A (m) a (m)+n (m)

Wherein Y (m) is the received signal value of m bit of UE transmission; The property the taken advantage of distortion factor that the channel fading of m the bit that A (m) sends for UE causes is greater than zero real number; A (m) is the BPSK numerical value of m ACK/NACK bit of UE transmission, value+1 ,-1 or 0; N (m) is an additive white Gaussian noise, and Normal Distribution N (0, σ _m ²), average is zero, mean square deviation is σ _m

The normpdf of n (m) is:

Formula two $f\left(x\right)=\frac{1}{\sqrt{2\mathrm{\π}}{\mathrm{\σ}}_m}\exp (-\frac{x^2}{2{\mathrm{\σ}}_m^2})$

Wherein, f is the probability density value, and x is the value variable, and exp () represents the exponent arithmetic of natural constant e.

The physical meaning of formula one is interpreted as: arrive receiving terminal when symbol a (m) sends through channel from transmitting terminal, channel makes this symbol produce the property the taken advantage of distortion (first) of channel fading and the additivity distortion (second) of white Gaussian noise.This is a public channel model.

According to the regulation of agreement, lose during for fear of bit information of independent transmission, adopt UE to send the ACK/NACK bit information here at every turn and it need be repeated to send ten times, be placed on transmission continuously in the time slot.Therefore, BS merges stack at receiving terminal with continuous ten received signals of identical ACK/NACK bit, and the result who obtains is as the judgement foundation of this ACK/NACK bit information.Might as well establish the sequence number m value 1,2 of these ten signals ... 10, amendment type one being expressed as of received signal Y that obtain superposeing then:

Formula three $Y=\underset{m=1}{\overset{10}{\mathrm{\Σ}}}Y\left(m\right)=\underset{m=1}{\overset{10}{\mathrm{\Σ}}}A\left(m\right)a\left(m\right)+\underset{m=1}{\overset{10}{\mathrm{\Σ}}}n\left(m\right)$

Because ten ACK/NACK bit value a (m) of this transmission all equate, can unify to represent with a, i.e. a (m)=a m=1,2 ... 10, so formula three is reduced to:

Formula four Y=Aa+n

Wherein, the property the taken advantage of distortion factor sum that A receives in channel for these ten ACK/NACK bits, the additive white Gaussian noise sum that n is subjected in channel for these ten ACK/NACK bits.

Consider that UE is when sending the ACK/NACK bit, in order to be complementary with the reliability requirement of different information, the power bias that sends ACK and NACK correspondence can be different, power was zero when transmission was not DTX, here for easy, the influence of different capacity biasing is embodied in the channel effect, and the property the taken advantage of distortion factor A that is about in the formula four is modified to:

Formula five

According to the stochastic variable addition rule of probability theory, and white noise sum n Normal Distribution N (0, σ ^{' 2}), average is 0, variance is the variance sum of former white noise, promptly ${\mathrm{\σ}}^{\′2}=\underset{m=1}{\overset{10}{\mathrm{\Σ}}}{\mathrm{\σ}}_m^2.$

From the probability theory angle, at the BS receiving terminal, the prior probability of three kinds of situations of the ACK/NACK bit value that UE sends equates, promptly is expressed as $P\{a=+1\}=P\{a=-1\}=P\{a=0\}=\frac{1}{3},$ Wherein P{} represents the probable value that situation takes place in the bracket.

Under three kinds of situations of ACK/NACK bit value, according to the probability distribution of formula four and white Gaussian noise, the probability density function of this signal value Y that receives of BS is expressed as f respectively for (deletion " being " word) _-1(Y) (when sending ACK), f _{+ 1}(Y) (when sending NACK), f ₀(Y) (during DTX):

Formula six $f_{-1}\left(Y\right)=\frac{1}{\sqrt{2\mathrm{\π}}{\mathrm{\σ}}^{\′}}\exp (-\frac{{(Y+A_{\mathrm{ACK}})}^2}{2{\mathrm{\σ}}^{\′2}})$

Formula seven $f_{+1}\left(Y\right)=\frac{1}{\sqrt{2\mathrm{\π}}{\mathrm{\σ}}^{\′}}\exp (-\frac{{(Y-A_{\mathrm{NACK}})}^2}{2{\mathrm{\σ}}^{\′2}})$

Formula eight $f_{+1}\left(Y\right)=\frac{1}{\sqrt{2\mathrm{\π}}{\mathrm{\σ}}^{\′}}\exp (-\frac{Y^2}{2{\mathrm{\σ}}^{\′2}})$

Because court verdict has three kinds of possibilities, need two threshold T here ₁(being used to adjudicate ACK and DTX), T ₂(being used to adjudicate DTX and NACK), according to probability theory, in order to make the mistake in judgment probability of various situations all minimum, described threshold value must satisfy equation:

f _-1(T ₁)＝f ₀(T ₁)；f ₊₁(T ₂)＝f ₀(T ₂)

According to formula six, formula seven, formula eight, more than two formulas find the solution and can obtain the optimal judgement threshold value and be expressed as follows:

Formula nine $T_1=-\frac{A_{\mathrm{ACK}}}{2}$

Formula ten $T_2=\frac{A_{\mathrm{NACK}}}{2}$

Resulting court verdict d is expressed as in the decision method that is to use these two threshold values:

Formula 11

The decision method of ACK/NACK bit among the HS-DPCCH is described below with reference to Fig. 1.

Enter step 11, receive ten ACK/NACK bits and stack that user terminal sends continuously, obtain signal Y.BS adopts RAKE receiver to receive ten signals that produced by same bits that UE sends, and stack demodulation gained result.

Then enter step 12, calculate two used threshold values of judgement according to formula nine, formula ten.In special uplink channel, can try to achieve the channel fading value by the DPCCH channel, can try to achieve AACK and ANACK according to ACK, NACK in the HS-DPCCH channel with respect to the power bias value of DPCCH channel then, can obtain threshold value by formula again.

Then enter step 13, adjudicate, obtain court verdict, be used for the interference cancellation Multiuser Detection according to formula 11.The court verdict that is obtained by this decision method is used for subscriber signal regeneration, guarantees the performance of interference cancellation Multiuser Detection like this.

Those of ordinary skill in the art are appreciated that in the decision method of described ACK/NACK bit, described method of reseptance can change according to actual conditions, and does not influence the spirit and scope of the invention.

For other signals except ACK/NACK, adopt the decision method of prior art to adjudicate.

This decision method is used for the subscriber signal regeneration of interference cancellation Multiuser Detection to ACK/NACK bit information judgement gained result; And requiring the judgement carried out according to the error rate of agreement regulation, the court verdict that obtains is used to feed back to the downlink processing unit of BS, is used for the transmission control of descending HSDPA data.Like this, both can guarantee descending HSDPA data throughout maximum; Can guarantee the performance of BS Multiuser Detection again.

Though by reference some preferred embodiment of the present invention, the present invention is illustrated and describes, but those of ordinary skill in the art should be understood that, can do various changes to it in the form and details, and the spirit and scope of the present invention that do not depart from appended claims and limited.

Claims (5)

1. confirm in the High-Speed Dedicated Physical Control Channel or the decision method of acknowledgement bit not, it is characterized in that, comprise following steps:

A receives at least two that described High-Speed Dedicated Physical Control Channel transmits continuously and confirms or the not signal and the stack of acknowledgement bit;

B calculates first threshold value and second threshold value according to channel fading parameters;

Signal value and described first threshold value and second threshold value of C after according to described stack adjudicated the described affirmation or the value of acknowledgement bit not by the judgement formula.

2. confirm in the High-Speed Dedicated Physical Control Channel according to claim 1 or the decision method of acknowledgement bit not, it is characterized in that, described affirmation or not the value of acknowledgement bit comprise affirmation, do not confirm and three kinds of states of discontinuous transmission.

3. confirm in the High-Speed Dedicated Physical Control Channel according to claim 1 or the decision method of acknowledgement bit not, it is characterized in that, in the described steps A, confirm or not acknowledgement bit signal and stack for ten that receive the continuous transmission of described High-Speed Dedicated Physical Control Channel.

4. confirm in the High-Speed Dedicated Physical Control Channel according to claim 2 or the decision method of acknowledgement bit not, it is characterized in that, described affirmation or not the judgement formula of acknowledgement bit be:

Wherein, d is the court verdict value, and Y is the signal value after the described stack, T ₁, T ₂Be described first threshold value and second threshold value, court verdict value-1 represent the affirmation state ,+1 the representative do not confirm state, 0 the representative discontinuous transmit status.

5. confirm in the High-Speed Dedicated Physical Control Channel according to claim 4 or the decision method of acknowledgement bit not, it is characterized in that the computing formula of described first threshold value and second threshold value is:

$T_1=-\frac{A_{\mathrm{ACK}}}{2};$ $T_2=\frac{A_{\mathrm{NACK}}}{2};$

Wherein, T ₁, T ₂Be described first threshold value and second threshold value, A _ACKFor send when user terminal be acknowledgement bit the time property the taken advantage of decline distortion factor that causes by channel fading and power bias, A _NACKFor what send when user terminal is the property the taken advantage of decline distortion factor that is not caused by channel fading and power bias during acknowledgement bit.