CN1066869C - Self-adjusting modulator - Google Patents

Abstract

The present invention relates to a self-adjusting quadrature modulator and a modulation method, which improves the precision that a digital signal is loaded on an RF carrier wave and is particularly to important for a Viterbi, a system of an echo synthesis demodulator and a system which adopts subtraction CDMA technology. The method and the modulator relates to a proper modulation estimating receiver for receiving transmission by self, and a modulation error is perfectly transmitted by a receiver determined relative to the theory. A measurement error is used for adjusting modulation to minimize the error. The modulation estimating receiver measures a phase and an amplitude (logarithm) by processing the signal of a logarithmic polar coordinate instead of I and Q components in the Cartesian form, and then the signal of the logarithmic polar coordinate is transformed into the Cartesian form. In addition, a correction factor which is determinated by the modulation estimating receiver can be directly indicated by a transformation component generated by the fast Walsh transformation.

Description

Self-adaptive modulator

The present invention relates to the radio transmitters optimized for digital data transfer, especially will improve the accuracy that be used for to be added in the numerical data on the wireless carrier frequency range by it by the mode of quadrature modulator.Improve the accuracy be added in the numerical data on the wireless carrier frequency range and be even more important, and for recently at Viterbi, echo-synthetic demodulator and be of great use to the exploitation of the aspects such as subtraction demodulation of code division multiple access (CDMA) modulation.

Background

Reach all over the world in the U.S., cellular telephone industry has obtained significant development in commercial operation.Well beyond the degree of estimating, and also exceeded power system capacity in the growth of main metropolitan area.If this trend continues to continue, the influence that increases rapidly will spread all over very soon even minimum market.Therefore the method for being badly in need of innovation satisfies ever-increasing capacity requirement, also will keep high quality services simultaneously and avoids the price that goes up.

In the whole world, important step of cellular system is the transformation by the analog to digital transmission.It is also important that and select an effective Digital Transmission mechanism to realize follow-on cellular telephony.Further say, extensively think first generation personal communication network (PCN) (PCN), (use cheap, pocket, cordless telephone, easy to carry and can stay at home, in the office or the street sending and receiving phone, or the like), will provide by the cellular carriers that uses Digital Cellular System infrastructure of future generation and honeycomb frequency.These desired key features of new system are the traffic carrying capacitys that increase.

The channel multiple access is realized by frequency division multiple access (FDMA) technology and time division multiple access (TDMA) technology at present.Shown in Fig. 1 (a), in FDMA, a communication channel is an independent radio band, and the transmission of power of a signal concentrates on wherein.Interference between adjacent channel can limit by using band pass filter, and the effect of band pass filter is only to allow the signal energy within designated frequency band to pass through.Therefore, if give different frequency of each channel allocation, power system capacity is subjected to the restriction of the restriction that available frequencies and channel heavily use so.

In tdma system, shown in Fig. 1 (b), a channel comprises a timeslice in the periodicity time interval string on the same frequency.Each cycle of timeslice is called a frame.A given signal energy is limited at one of these timeslices.Interference between adjacent channel can by service time storbing gate method control, or with other permission in the corresponding time period lock unit by signal energy.Like this, the interference problem that is caused by different relative signal strength level has just reduced.

Can increase the capacity of a tdma system by transmission signals being compressed in a method in the shorter timeslice.One of its result, the pulse rate that sends information must correspondingly significantly speed, and so shared amount of frequency spectrum is also wanted proportional increase.Thereby in Fig. 1 (b) shared frequency band than Fig. 1 (a) in shared bandwidth.

The system that uses FDMA or tdma system or FDMA/TDMA to use with its objective is and guarantees that two potential interference signals can not take same frequency simultaneously.Antithesis, code division multiple access (CDMA) allows signal overlapping on time and frequency, shown in Fig. 1 (c).Like this, all CDMA signals are shared same frequency spectrum.No matter in frequency domain still in time-domain, multiplexed signal all is overlapping.In theory, the inter-area traffic interarea that send be added in generate by the pseudo noise code maker, on data flow with high bit rate more.This inter-area traffic interarea and this high bit rate data flow are compounded in together.Combination between this high bit rate signal and the low bitrate data streams is called coding or cries this inter-area traffic interarea signal spread-spectrum.Each inter-area traffic interarea or channel are assigned with a unique spreading code.A plurality of information encoded signals send on radio frequency carrier, and receive together as a composite signal at receiver end.No matter on frequency still in time, each signal that is encoded with the every other signal that is encoded, comprise that the relevant signal of noise all is overlapping.Relevant by this composite signal and a unique spreading code are carried out, just corresponding information signal can be separated and decodes.

The cdma communication technology has some advantages.Capacity range based on the cellular system of CDMA shows 20 times that can reach existing analogue technique system, this is the result of cdma system broadband character, for example improved coding gain/modulation density, the phonetic speech power gating reaches in each unit the subregion of same frequency spectrum and heavily use.In fact CDMA has avoided the multichannel interference, and has eliminated decay and day electrical interference, and improves the performance of urban area.CDMA sends voice by a high bit rate decoder and has guaranteed high, desirable voice quality.CDMA also provides different data rate to satisfy the voice quality of different stage.The signal format that mixes of CDMA has thoroughly been eliminated crosstalk and has been made eavesdropping or follow-up call become very difficult, very expensive, thereby has guaranteed caller's the bigger right of privacy, avoids the deceptive practices of room and time better.The people showed at K.Gilhousen etc., Trans.on VehicularTechnology magazine the 40th volume of stepping at IEEE, in 1991 the 5th phases the 303rd to 312 page the paper " On the Capaity of a Cellular CDMA Systems ", introduced the every aspect of cdma communication.

In the system that optimizes for digital data transfer, because its improved efficient, polynary (M-ary) Ditital modulation method often is used to, and wherein is sent out away at one of each sigtnal interval M possible signal.A method of often using is orthogonal PSK (QPSK), and wherein the signal with the quadrature phase of two constant amplitudes is added on the carrier wave.Another normally used method is skew QPSK (OQPSK), and promptly maximum phase changes and changes little than the maximum phase on the QPSK waveform on any point of the waveform after modulated.The result is that compound OQPSK signal so more approaches the required constant envelope of this type of signal through after the bandpass filtering littler envelope waveform being arranged.What deserves to be mentioned is that QPSK and OQPSK are the forms of quadrature amplitude modulation (qam).The various characteristics of these modulator approaches are all statements to some extent in some articles, for example, by the 590th～596 page of Introduction to Communication Systems second edition that F.Strember showed, publish by Addison-Wesley publishing company, note, Massachusetts is in nineteen eighty-two; By " the MAK andoffset QPSK Modulation " that S.Gronemeyer showed, IEEE Trans on Commurications COM-24 volume, 1976 the 8th phases, the 809th～820 page.

An example of the system that optimizes for digital data transfer is a cdma system, and wherein the demodulation to orthogonal demodulation signal comprises, ripple and ripple of being modulated by imaginary data pattern in theory of receiving compared, for example, the Viberbi demodulator.Another example of this system is a cdma system, wherein at first with a stronger signal demodulation, it is separated from the signal of receiving before at one that will be left then than the weak signal demodulation, resemble the U.S. patent No. 5 of common transfer, 151,919 and 5,218, a kind of described in 619.These two documents are here quoted as a reference.

Typical quadrature modulator utilizes the advantage of the quadrature phase of sinusoidal wave and cosine wave, and information rate is modulated on the wireless carrier for twice.For example, can be on cosine wave with the even bit bit modulation of certain digital information data stream, and with the odd bits bit modulation of digital information data stream on sine wave.In quadrature modulator, if the phase place of sinusoidal wave and cosine wave is not 90 ° of positive good jobs, or whenever sinusoidal wave and the cosine wave amplitude is just in time equal, or whenever modulating wave should be zero and when remaining leakage loss occurring, or owing to some other reason or the like, all mistake can appear.Certainly, quadrature modulation be used for one synthetic, in theory with imaginary data-modulated or be very important with the accuracy of the ripple coupling of receiving data-modulated for above-mentioned communication system.The accuracy of quadrature modulator is to guarantee the correct coupling between the sequence and adjust to keep to reduce remnants wrong these the two kinds of methods that do not match by being used in combination traditionally.

A quadrature modulator commonly used, as shown in Figure 2, comprise one " homophase " or I modulator 101, one " quadrature " or Q modulators 102, with a phase split network 103 that is used to provide double-side band, use cosine and sinusoidal carrier frequency signal suppressed carrier modulator 101,102 respectively.Say that ideally the signal that network 103 provides should be cos (ω t) and sin (ω t), wherein ω is the angular frequency of carrier signal.I in Fig. 2 and Q modulation maker 104 are to be used to provide I and Q modulation signal, and hybrid network 105 is used for the output addition of I modulator 101 and Q modulator 102, and carrier wave equilibrium/d.c that trim-pot 106 and 107 is used separately as I, Q signal is offset adjustment.Two other trim-pot 108 and 109 is used separately as the amplitude matches of I, Q signal among Fig. 2.Phase split network 103 is also adjustable, shown in the diagonal arrow, in order to obtain the near possible exact value of 90 ° of phase differences between required sine and the cosine CF signal.

In actual conditions, if I modulator and Q modulator are to be configured on the same chip by integrated circuit technique, they will quite mate, and therefore, do not need amplitude adjusted voltage divider 108 and 109 probably.Similarly, in some cases, the purpose of phase split network 103 can obtain by the following method: with frequency is that the signal of 4 ω begins, i.e. wanted carrier 4 times of ω frequently, and go a Digital Logic is removed 4 circuit regularly with 4 ω-signal, this circuit can produce bit mode:

0011001100110011... and 0110011001100110 ... it can be taken as be square wave with 1/4 frequency of an accurate cycle (90 °) 1/4 4 ω bit rates at interval.Usually drive I and Q modulator with the square wave carrier signal, and without sine wave-shaped signal.The digital method of 90 ° of phase signals of above-mentioned generation is practical for frequency within the hundreds of megahertz range, if but in higher frequency, the minute differences on the logical circuit speed of packing into will become the important source of modulator error once more.

Carrier wave equilibrium and/or d.c skew is tuning mainly be guarantee when modulation generator 104 it I and Q output on when producing a zero-signal, it is zero too that corresponding carrier frequency at I, Q modulator is exported.This just requires I modulator 101 is that one zero I modulates one zero cosine signal of generation, and the Q modulator is zero sinusoidal signal of one zero Q modulation generation.We know, are 0 o'clock at cosine signal, and in fact the balanced imbalance of I modulator can produce a sinusoidal signal, and are 0 o'clock in sinusoidal signal, and in fact the balanced imbalance of Q modulator produces a cosine signal.Therefore, the small cosine that the I modulator produces decreases to leak and can be used for the balanced cosine leakage loss that is produced by the Q modulator sometimes, and the slight sinusoidal that the Q modulator produces is leaked to carry and can be used for the balanced sinusoidal leakage loss that is produced by the I modulator sometimes.But, use trim-pot 106,107 can more easily realize the carrier wave equilibrium.

Modulate non-accurate other reasons and be non-linear on the non-linear and modulation generator 104 on the modulator 101,102.Generator 104 digitally produces the fore-runner of I, Q signal usually by a digital signal processor, convert this fore-runner to modulated-analog signal by digital-to-analogue (D/A) transducer then.Not matching between I signal D/A converter and Q signal D/A converter, perhaps Zhi Hou anti-alias filter all is to cause modulation error further to originate.In some cases, digital signal processor is with the anti-phase predistortion of coming computation of modulation signals of the non-linear transform function of modulator 101,102, non-linear in order to compensating for modulator.We also know, simplify the technology of removing false filter of D/A conversion and back by the delta modulation method of using highly excessive sampling, can reduce some aforesaid modulation errors.One of this technology is entitled as in the U.S. patent application the 07/967th, 027 of common appointment in the literary composition of " multi-mode signal processing " to be described to some extent, quotes this article here as a reference.

Disclose a modulating system the 4th, 985, No. 688 for the U.S. patent of Nagata, an output signal amplification, that modulate is fed back to a quadrature demodulator.This signal compares by demodulation and with a threshold value.On this comparison basis, produce a control signal, in order to the amplifier nonlinearity that links to each other with modulator in the regulating system.When surpassing thresholding, obviously normal modulation is interrupted, and replaces with the 1/N of this frequency or data transfer rate.This Nagata patent has also been introduced and how to be determined moment by a differentiator, divider circuit and clock control device sampling is carried out in quadrature demodulator output.

The equipment of this Nagata patent also can be described as the device of adaptive, a self study predistortion.The purpose of above-mentioned Nagata patent is that the input predistortion of quadrature modulator is reverse, so that the output after the distortion power amplifier can obtain correcting.On the other hand, the equipment of Nagata patent is difficult to the mistake in the quadrature modulator is corrected, because it comes misjudgment with a quadrature demodulator, and as described above, this demodulator also runs into the error with the modulator same-type probably.In a word, if a people can make a perfect demodulator, he also can be with it as a perfect modulator so.

To people's such as Carney U.S. patent the 4th, 581,749, Carney discloses a kind of frequency modulation(FM) equipment that can be used in the mobile communication system.A feedback control loop can come the pilot angle modulation error by the deviation value of a departure after more modulating and a prediction.Described automatic modulation error-correcting system is mainly used in pure transmitter, particularly binary system continuous phase frequency shifts keying (CPFSK) with angle modulation.

In the described system of above-mentioned Carney patent, produce an accurate modulation index by between two exact values, digitally carrying out the frequency switching.But such modulation also is not used in transmission, because should change non-filtered.Send waveform and utilize the 1-0 after the shaping to comprise frequency spectrum, and when having occurred abundant similar bit in the sequence, also should the approaching not same value of the modulation of shaping through the frequency departure of the modulation of shaping.The appearance of these strings of similar bit is detected, and it is compared, and its result is used for feedback control loop to adjust modulation index.Like this, the Carney patent is when being modulated to the string of sufficiently long 1 or 0 composition, just evaluated error.

To people's such as Cahill U.S. patent the 5th, 020,076, then described with the analog frequency modulation (FM) in a carrier signal source of habitual method modulation and with conversion between the method for a quadrature modulator modulation signal.When adopting FM commonly used, in circuit, put into quadrature modulator, and this I and/or Q modulation signal be set to a constant, so that the FM signal directly passes through from quadrature modulator.

Give the U.S. patent the 4th, 856,025 of Takai, described the transmission diversity realization that is used to improve digital wireless communication.Wherein used a special waveform and special receiver, still, this special receiver is not estimated the accuracy of transmitter modulates, and coming provides information for the modulation error correction system.

From the above, the high modulation precision obtains by following outstanding PRACTICE OF DESIGN, promptly compensates fixing, immutable shortcoming in conjunction with special, fixing, adjustment completely.Equally can be continuously, alternatively describe how to adjust and the modulation of compensate for variable non-accurately and error.

Brief summary

According to the present invention, transmitter receives its transmission signal and the transmission modulation error with respect to theory form of definite receiver expectation with an appropriate receiver.On the direction that reduces error on the modulating wave, alternatively do some adjustment, ideal waveform desirable up to converging to.

In one embodiment, a digital signal processor digitlization produces I, Q modulating wave, and do some numercal adjustment by the following method, promptly obtain the carrier wave equilibrium by increasing skew, ratio by multiplication obtains I, Q coupling, compensates 90 °-phase place-cut apart error by I, Q cross-couplings.Estimate that by the modulation of on the transmitter output sample, operating receiver upgrades numeral continuously and adjusts.

If the modulator of certain specific type (or demodulator) is for the modulation distortion sensitivity of some specific type, so this modulator can be used for detecting and digital regulated necessary modulating characteristic is brought in constant renewal in report, especially when the noiseless sampling that is transmitted signal is estimated.A modulation estimates that receiver is used in the following system, i.e. this modulation is a spread-spectrum signal with quadrature or bi-orthogonal coded.

Be used for accurately forming adaptively precompensating quadrature modulator according to an aspect of the present invention, comprise through modulation signal:

First processor applies a correction factor to the not correction of in-phase modulation waveform and quadrature modulation waveform sampling, thereby produces calibrated sampling, and calibrated sample conversion is become calibrated in-phase modulation waveform and quadrature modulation waveform;

Quadrature modulator applies an in-phase modulation waveform to the carrier wave of cosine in fact, and applies calibrated quadrature modulation waveform to being actually sinusoidal carrier wave, thereby produces modulated signal;

Receiver is estimated in the modulation that is connected on the quadrature modulator, produces the digitized sampling through modulation signal; With

Be connected to first processor and modulation and estimate second processor of receiver, determine correction factor according to digitized sampling and not calibrated sampling, and send correction factor to first processor.

Be used for accurately forming the adaptively precompensating quadrature modulation method of modulated signal according to a further aspect of the invention, comprise the steps:

(a) one group correction factor is added on uncorrected homophase and the quadrature modulation waveform sampling, to produce the homophase and the quadrature modulation sampling of proofreading and correct;

(b) form calibrated in-phase modulation waveform from the in-phase modulation sampling of having proofreaied and correct, and with carrier wave that is actually cosine wave of the in-phase modulation waveform modulated of having proofreaied and correct, the calibrated quadrature modulation waveform of formation from the quadrature modulation of having proofreaied and correct sampling, and be actually sinusoidal wave carrier wave, and by modulated cosine carrier is formed modulated output signal mutually with sinusoidal carrier with this of calibrated quadrature modulation waveform modulated;

(c) by will this modulated output signal up-conversion and be amplified to a transmission frequency that choose, desired and power level, form modulated transmission signal;

(d) collect the digital sample of this modulated transmission signal;

(e) determine the correction factor group from described digital sample and not calibrated sampling.

The summary of accompanying drawing is described

Read following detailed description, and accompanying drawings, the feature and advantage that the present invention may be better understood.

Fig. 1 (a)-(c) is the figure with the access channel of different multiple access technologies.

Fig. 2 is the functional block diagram of a typical quadrature modulator.

Fig. 3 is the functional block diagram of a system according to the invention.

Fig. 4 has shown how the CDMA signal produces.

Fig. 5 and Fig. 6 show how the CDMA signal decodes.

Fig. 7 has illustrated that is subtracted each other CDMA demodulation techniques.

Fig. 8 (a), 8 (b) are the transmitter of spread spectrum communication system and the block diagram of receiver.

Fig. 9 shows the waveform of shaping offset quadrature amplitude modulation(PAM) (SOQAM).

Describe in detail

Though following description is relevant cellular communication system,, will be appreciated that then that for the personage who relatively is proficient in this regard the present invention also can be used for other communications applications systems comprising portable or mobile radiotelephone and/or personal communication network (PCN) (PCN).Further, the present invention promptly so can be used for one and subtracts each other the CDMA demodulating system, and it can be used for the application of the spread spectrum system of other type equally.The defective of quadrature modulator

For ease of understanding the present invention, at first provide an Analysis on defects that in quadrature modulator, may occur.

If I, Q channel have a balanced imbalance gain, the gain of one of them channel is the geometric mean (IQ) of amplitude Q of the Q channel of the amplitude I of an I-channel input that is higher than non-modulated and non-modulated like this ^1/2Factors A, the gain of one other channel is one and is lower than (IQ) ^1/2Factors A, if and sinusoidal and cosine wave signal is not just in time to differ 90 °, but for certain average phase, there is phase error+δ φ on the carrier signal, and have phase error-δ φ on another carrier signal, the cartesian form of modulator output signal should be written as so:

AIcos (ω t+ δ φ)+(Q/A) sin (ω t-δ φ) can extend into:

cos(ωt)[cos(δφ)AI-(sin(δφ)/A)Q]+sin(ωt)[(cos(δφ)/A)Q-sin(δφ)AI]。Definition C=cos (δ φ), S=sin (δ φ), represent that with the matrix determinant modulator output signal becomes:

Because more wish to have following form: Can find out the following condition that needs:

And when satisfying following formula during condition below existing: Because common factor 1/ (c ²-S ²) be an overall magnitude size, it can be lost.Similarly, the right can be removed by c=cos (δ φ), and definition of T=tan (δ φ)=S/C obtains following result: Following formula can be write as with non-determinant form: I=(I ₀+ TQ ₀)/A and Q=(Q ₀=TI ₀) A.

Above numerical analysis show, under the defective situation of modulator, still can obtain wanting the modulation that obtains, as long as with Q ₀A part of T and I ₀Addition, then divided by A, and, with I ₀A part and Q ₀A is multiply by in addition then.

Having ignored a defective in the analysis in front is exactly carrier wave equilibrium imbalance, and this can need equal balanced constant K i, the Kg that lacks of proper care of carrier wave that proofreaies and correct to take into account by cutting from I, Q.The last cartesian equation formula of I, Q is: I=(I ₀+ TQ ₀)/A-ki and Q=(Q ₀+ TI ₀) A-kg

According to the present invention, correction factor A, T, Ki and Kg determine by the following method: estimate that by a modulation receiver comes the output waveform of modulator is sampled, and sampling is passed to the precorrection of a digital signal processor to produce I, Q modulation and to carry out providing above.

Normally, modulation estimates that receiver must have a kind of device can measure actual I, the Q value that is produced by the quadrature modulator of transmitter, also will have a kind of device I, the Q value of measuring gained can be compared with desirable I, Q value, to determine correction factor simultaneously.But receiver commonly used is used when a wireless signal is resolved into I, Q component usually is quadrature modulator circuit with the used same type of transmitter, but operation is opposite.As described above, the mistake that will distinguish modulator in theory in this case from the mistake of demodulator is impossible.

For fear of this wrong indistinguishability, a modulation according to an aspect of the present invention estimates that receiver makes land used count polar coordinates signal processing method and measures the phase place of sender signal and the logarithm of its amplitude, rather than uses I, the Q component of cartesian form.After the digitlization, receiver digitally becomes desirable cartesian form with the log-polar formal transformation of measured value.Log-polar signal processing method is introduced in U.S. patent the 5th, 048,059 to some extent.

Be a simple procedure of estimating correction factor below, given one group of desirable I, Q value, Ij and Qj, at j=1 ... N, also have under the measured value Ij ' and Qj ' of one group of corresponding I, Q, supposing has: the B that can satisfy equation (1) and (2), C are found out in Ij '=BIj-BTQj+Ki (1) and Qj '=CQj-CTIj+kg (2) and hope, T=tan (δ φ), Ki and Kg.

At first, ideal value Ij and Qj are divided into two subclass, first subclass { Ij ^PosI, Qj ^PosIAn Ij on the occasion of, and second subclass { IjnegI, Qj ^NegIOnly comprise the negative value of Ij.If the value that the value that subclass comprised comprises more than another subclass, two subclass are all only used N ₁Value (N ₁Equal wherein the number of the value that comprises than smaller subset).

Definition I _SLFor the Ij value at positive subclass { Ij ^PosI, Qj ^PosIIn carry out N ₁Summation: $I_{s1}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}I{j}^{\mathrm{posI}},$ And Q _S1Be defined as at positive subclass { Ij ^PosI, Qj ^PosIIn the Qj value is carried out N ₁Summation: $Q_{s1}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}Q{j}^{\mathrm{posI}}$ 。

Definition I ' _S1For corresponding to positive subclass { Ij ^PosI, Qj ^PosISubclass Ij ' ^PosI, Qj ' ^PosIIn Ij ' is carried out N ₁Summation: $I_{s1}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}I{j\′}^{\mathrm{posI}},$

Definition Q ' _S1For corresponding to positive subclass { Ij ^PosI, Qj ^PoslSubclass Ij ' ^PosI, Qj ' ^PosIIn Qj ' is carried out N ₁Summation: $Q_{s1}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}Q{j\′}^{\mathrm{posI}},$

Because selected calculating I _S1The I value all be on the occasion of, and obtain Q with adding up _S1The symbol of corresponding Q value and uncorrelated, so I _S1Usually can compare Q _S1Much bigger.

Definition I _S2For at negative subclass { Ij ^NegI, Qj ^NegIIn carry out N ₁Summation: $I_{s2}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}I{j}^{\mathrm{negI}},$ Definition Q _S2For at negative subclass { Ij ^NegI, Qj ^NegIIn the Qj value is carried out N ₁Summation: $Q_{s2}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}Q{j}^{\mathrm{negI}}$

Similarly, I ' _S2Be defined as with negative subclass { Ij ^NegI, Qj ^NegICorresponding subclass { Ij ^NegI, Qj ' ^NegIIn Ij ' is carried out N ₁Summation: ${I\′}_{s2}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}I{j\′}^{\mathrm{negI}},$

Definition Q ' _S2For with negative subclass { Ij ^NegI, Qj ^NegICorresponding subclass { Ij ^NegI, Qj ' ^NegIIn Qj ' is carried out N ₁Summation: ${Q\′}_{s1}=\underset{j=1}{\overset{N_1}{\mathrm{\Σ}}}Q{j\′}^{\mathrm{negI}}$ 。

Calculate I because add up _S2All I values all are chosen as negative value, add up to obtain Q _S2The symbol of corresponding Q value go irrelevant therewith, therefore I usually _S2Than Q _S2Big a lot.

By top equation (1) as can be known, corresponding to positive subclass { Ij ^PosI, Qj ^PosI, subclass Ij ' ^PosI, Qj ' ^PosIIn Ij ' is carried out N ₁Summation: I ' _S1=BI _S1-BTQ _S1+ N ₁Ki (3) equally as can be known from equation (1), corresponding to negative subclass { Ij ^NegI, Qj ^NegI, subclass Ij ' ^NegI, Qj ' ^NegIIn Ij ' is carried out N ₁Be summed to:

I ' _S2=BI _S2-BTQ _S2+ N ₁Ki (4) deducts equation (4) from equation (3), but cancellation Ki obtains: $B=\frac{({I\′}_{s1}-{I\′}_{s2})+\mathrm{BT}(Q_{s1}-Q_{s2})}{(I_{s1}-I_{s2})}=\frac{({I\′}_{s1}-{I\′}_{s2})}{({I\′}_{s1}-{I\′}_{s2})}\[1-$ $\frac{T(Q_{s1}-Q_{s2})}{(I_{s1}-I_{s2})}{\]}^{-1}$ 。Because T is less, and (Q _S1-Q _S2) than (I _S1-I _S2) little many, be easy to obtain the answer of B: the T value on following formula the right original (initially) is replaced by B.

Next, more desirable Ij and Qj value are divided into two subclass, first subclass Ij ^PosQ, Qj ^PosQOnly comprise Qj on the occasion of, second subclass { Ij ^PosQ, Qj ^PosQOnly comprise the negative value of Qj.If the value that one of them subclass comprises is more than another subclass, two subclass are all only used N so ₂(N ₂Equal the number of the less value that subclass comprised).

Definition I _S3For at positive subclass { Ij ^PosQ, Qj ^PosQIn Ij is carried out N ₂Summation: $I_{s3}=\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}I{j}^{\mathrm{posQ}},$ Definition Q _S3For at positive subclass { Ij ^PosQ, Qj ^PosQIn the Qj value is carried out N ₂Summation: $Q_{s3}=\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}Q{j}^{\mathrm{posQ}}$ 。

Definition I ' _S3For corresponding to positive subclass { Ij ^PosQ, Qj ^PosQSubclass { Ij ^PosQ, Qj ' ^PosQIn Ij ' is carried out N ₂Summation: ${I\′}_{s3}=\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}I{j\′}^{\mathrm{posQ}},$

Definition Q ' _S3For, corresponding to positive subclass { Ij ^PosQ, Qj ^PosQSubclass Ij ' ^PosQ, Qj ^PosQIn Qj ' is carried out N ₂Summation: ${Q\′}_{s3}=\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}Q\′j^{\mathrm{posQ}}$

Because adding up, all calculate Q _S3The Q value just all elect as, and obtain I with adding up _S3The symbol of corresponding I value irrelevant, therefore Q usually _S3Compare I _S3Many greatly.

Definition I _S4For at negative subclass { Ij ^NegQ, Qj ^NegQIn carry out N ₂Summation: $I_{s4}=\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}I{j}^{\mathrm{negQ}}$ Definition Q _S4For at negative subclass { Ij ^NegQ, Qj ^NegQIn the Qj value is carried out N ₂The value summation: $Q_{s4}=\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}Q{j}^{\mathrm{negQ}}$

Use similar method, definition I ' _S4For corresponding to negative subclass { Ij ^NegQ, Qj ^NegQSubclass Ij ' ^NegQ, Qj ' ^NegQIn Ij ' is carried out N ₂Summation: ${I\′}_{s4}=\underset{j=1}{\overset{N}{\mathrm{\Σ}}}I{j\′}^{\mathrm{negQ}},$

Definition Q ' _S4For corresponding to negative subclass { Ij ^NegQ, Qj ^NegQSubclass Ij ' ^NegQ, Qj ' ^NegQIn Qj ' is carried out N ₂Summation: ${Q\′}_{s4}=\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}Q{j\′}^{\mathrm{negQ}}$

Calculate Q because add up _S4All Q values all are chosen as negative value, add up to obtain I _S4The symbol of corresponding I value irrelevant, therefore Q usually _S4Value than I _S4Big a lot.

Can obtain with respect to positive subclass { Ij by equation (2) ^PosQ, Qj ^PosQSubclass { Ij ^PosQ, Qj ' ^PosQIn Qj ' is carried out N ₂Summation:

Q ' _S3=CQ _S3-CTI _S3+ N ₁Kg (5) can also obtain negative relatively subclass { Ij from equation (2) equally ^NegQ, Qj ^NegQSubclass Ij ' ^NegQ, Qj ' ^NegQIn Qj ' is carried out N ₂Summation:

Q ' _S4=CQ _S4-CTI _S4+ N ₂Kg (6) deducts equation (6) from equation (5), but cancellation Kg obtains: $C=\frac{({Q\′}_{s3}-{Q\′}_{s4})+\mathrm{CT}(I_{s3}-I_{s4})}{(Q_{s3}-Q_{s4})}=\frac{({Q\′}_{s3}-{Q\′}_{s4})}{(Q_{s3}-Q_{s4})}\[1-$ $\frac{T(I_{s3}-I_{s4})}{(Q_{s3}-Q_{s4})}{\]}^{-1}$ 。Because T is less, and (I _S3-I _S4) than (Q _S3-Q _S4) much smaller, be easy to obtain the answer of C: the old value (initial value) of the T value on top expression formula the right is substituted by C.

Similarly, can draw with respect to positive subclass { Ij from equation (2) ^PosI, Qj ^PosISubclass { Ij ^PosI, Qj ^PosIIn Qj ' value is carried out N ₁Summation:

Q ' _S1=CQ _S1-CTI _S1+ N ₁Skg (7) can draw with respect to negative subclass { Ij from equation (2) equally ^NegI, Qj ^NegISubclass Ij ' ^NegI, Qj ' ^NegIIn Qj ' value is carried out N ₁Summation:

Q ' _S2=CQ _S2-CTI _S2+ N ₁Kg (8) deducts equation (8) from equation (7), and cancellation kg obtains: $T=\frac{({Q\′}_{s2}-{Q\′}_{s1})+C(Q_{s1}+Q_{s2})}{C(I_{s1}+I_{s2})}$

Further, can obtain with respect to positive subclass { Ij from equation (1) ^PosQ, Qj ^PosQSubclass Ij ' ^PosQ, Qj ' ^PosQIn Ij ' is carried out N ₂Be summed to:

I ' _S3=BI _S3-BTQ _S3+ N ₂Ki (9) also can obtain with respect to negative subclass { Ij from equation (1) equally ^NegQ, Qj ^NegQSubclass Ij ' ^NegQ, Qj ' ^NegQIn Ij ' is carried out N ₂Be summed to:

I′ _s4=BI _s4-BTI _s4+N ₂ki (10)。Subtract equation (10) from equation (9), cancellation ki can get: $T=\frac{({I\′}_{s4}-{I\′}_{s3})+B(I_{s3}+I_{s4})}{B(Q_{s3}-Q_{s4})}$

The renewal answer formula of B and C in the top expression formula is used for T, just obtains the answer formula of the renewal of T.At last, in equation (1) and (2), be replaced into new value A ^New, B ^New, T ^New, and to Ij, Qj, Ij ' and Qj ' carry out the N summation, then obtain the new answer formula of Ki and Kg: $K_i^{\mathrm{new}}=\frac{1}{N}\underset{\text{j=1}}{\overset{N}{\mathrm{\Σ}}}\[{I\′}_j+B^{\mathrm{new}}(T^{\mathrm{new}}{Q}_j-I_j)\],$ With for Kg: $K_q^{\mathrm{new}}=\frac{1}{N}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\[{Q\′}_j+C^{\mathrm{new}}(T^{\mathrm{new}}{I}_j-Q_j)\].$ The adaptive quadrature modulator

Figure 3 shows that a self-adaptive modulator of realizing said process.First digit signal processor 110 receives the information signal that will send, and converts thereof into I, the Q waveform that meets corresponding modulation technique.I, Q waveform are converted to quadrature modulator 114 needed analog waveforms by number-Mo (D/A) transducer 112,113 (being respectively applied for I, Q waveform) again from the digital value that is produced by digital signal processor 110.The advantage of the characteristics of quadrature modulator and high bit rate δ-∑ modulation all has introduction in U.S. patent application the 07/967th, 027, quote here with for referencial use.Can at an easy rate the bit stream of high bit rate δ-∑-modulation be converted to the aanalogvoltage of their representatives by the method that on a big string bit, forms moving average voltage.This can by one have certain bandwidth be the sub-fraction of bit rate and be enough to pass through continuous time of the part that is hopeful to modulate, low pass filter is realized.If want the structure of equalizing signal, then also to use equalization filter.

On the commercial market, be easy to buy the quadrature modulator integrated circuit, for example from Hewlett-Packard company (model is MX2001), from Siemens company (model is PMB2200).These circuit all have balanced I, Q input.If not converting digital I, Q value to analog waveform with high bit rate δ-∑ modulation, but with a D/A converter commonly used, for example 8-position or 12-position equipment, then or will with 4 equipment that are complementary come driven modulator ± I and ± Q input, perhaps will be with a pair of equipment that balanced output is arranged.But, δ-∑ technology can be integrated in a sub-fraction in the bigger digital integrated circuit fully, thus avoid using D/A converter commonly used with complexity.

Upconverter 115 comprises a frequency converter and corresponding band pass filter, changes the output of quadrature modulator 114 into transmitted frequency from intermediate frequency (quadrature modulator 114 can be operated easily in this frequency range usually).Power amplifier 116,117 is brought up to the required value of transmission with power level.The sampling of the transmission signals of coupler 118 after arbitrary on the chain after the modulation extracts a modulation on easily.In Fig. 3, because sampled signal is to extract on the frequency of level eventually before the whole level transmission power amplifier 117, this sampling by low-converter 119 friendships is and required chopping phase suitable frequency relatively frequently.A local oscillator frequencies synthesizer 120 can be conveniently used for driving and submit device 115 and low-converter 119 frequently.Also can realize down-conversion in addition, suppose this frequency synthesizer output of reference frequency standard 121 and its frequency synthesis, other frequency f that all are used by low-converter 119 and another one local oscillator frequencies synthesizer ₁To f ₈Also by 121 outputs.We can expect that the mistake after modulation transmissions chain post-sampling signal can be accomplished modulator in the part is corrected.

Sampling by coupler 118 down-conversion signal of extracting from the transmission signal after the modulation is subject to the log-polar digitlization that utilizes intermediate frequency amplifier 122, and this amplifier 122 produces the natural logrithm of an output signal and the instantaneous amplitude of this signal sampling and one and kept the hard-limiting signal of instantaneous signal phase information approximately to be directly proportional.The logarithm range signal is by corresponding mould-number (A/D) transducer 123 carries out digitlization, and hard-limiting, and the phase place inhibit signal carries out digitlization by respective phase Aristogrid 124.Phase place digitizer 124 can be constructed by the method for introducing in the U.S. patent the 5th, 148,373.Here introduce and only be reference.

Modulus (A/D) transducer 123 can reach 8 bits with precision with the method for successive approximation.Use another kind of method, A/D converter 123 uses high bit rate δ-∑ modulation method with signal digitalized earlier, advances filter by one ten then high bit rate δ-∑ bit stream is become the low rate stream that neck is a binary number down.High bit rate delta modulation method or compression expansion delta modulation method can adopt, but have the latent differential (being the rate of change of its measuring-signal logarithm amplitude) that closes to be recovered by digitally multiple integral afterwards.The advantage of a kind of technology in back is, changes by a small margin and can be distinguished easily, and this has for those, and maybe should to have the modulator approach of modulating composition by a small margin be a key factor.

Be sent to second digit signal processor 125,125 by the log-polar digitized signal sampling of A/D converter 123 and phase digitization device 124 outputs and also receive (not correcting) I, Q modulation signal simultaneously by 110 outputs of first digit signal processor.Second digit signal processor 125 carries out the phase place adjustment of signal sampling by the method that adds a digital phase pushing figure at phase sample patrix-2 π before changing to Descartes at log-polar.Second digit signal processor 125 is adjusted with phase place then, compare by certain suitable processing method (for example above-mentioned introduction) through the signal sampling of log-polar-Descartes's conversion and desirable I, Q modulation value, thereby determines the correction factor that those will feed back to first digit signal processor 110.First these correction factors of processor 110 usefulness come for modulation and send to generate correct, from suitable I, Q waveform.Phase place is adjusted constant (± δ φ) and also can be upgraded by the technology that similar front had been introduced, and the continuous cycle can cause continuous correction.Certainly, the function of processor 110,125 also can be finished by the signal processor of a suitable function.A proper digital signal processing chip can be, for example, the model that is gone out by Texas Instruments is TMS 320 C50 chips, and this chip can be operated under command speed is at least 20MIPS.

Should understand the imperfection of I, Q modulator and defective to being constant basically in the concrete time period, change very slowly in other words, for example, because variations in temperature etc., so correction factor does not need usually to upgrade.On the other hand, if condition needs, correction factor also can be brought in constant renewal in, even the accidental correction factor that upgrades also can obtain one-time fixing the compensating for modulator method of adjustment in the convenient all better system of sensitiveness, interactivity and accuracy with respect to what know previously.When being used in the subtraction cdma system that adopts quadrature encoding, as introducing in above-mentioned U.S. patent and patent application, the present invention especially has advantage.Introduce the CDMA demodulation techniques below in conjunction with signal graph shown in the figure (Fig. 4-6), Fig. 4～6th, the waveform example in traditional cdma system in coding, the decode procedure.Fig. 7 then illustrated a waveform example that utilizes Fig. 4～6, its performance of having improved of subtraction CDMA demodulation techniques.

Fig. 4 (a) is two different data flow with (d), the digital information that representative will communicate on two mutual independently channels.The digital coding of high bit rate of information signal 1 usefulness, unique representation signal 1 is modulated, and this is encoded as signal shown in Fig. 4 (b).For purpose of description, term " bit " refers to the symbol of a binary digit or an information signal.Term " bit period " refer to a bit initial of information signal and finish between the time interval.Term " sheet " refers to a binary digit of high bit rate code signal.Accordingly, term " sheet cycle " refers to the time interval between the starting and ending of a code signal sheet.Very natural, bit period is more much bigger than the sheet cycle.Tiao Zhi result is actually the product of these two signal waveforms like this, shown in Fig. 4 (c).With boolean's form of explanation, the modulation of these two binary waveforms is actually an xor operation.A series of similar operation that information signal 2 is done are shown in Fig. 4 (d)-(f).In actual applications, a plurality of encoded information signals that have certainly more than 2 are dispersed on the cellular telephone communication available spectrum.

Each code signal can as QPSK, be modulated a RF carrier wave with in one group of modulation technique any.In a cell phone system, each modulated carrier wave sends out by air interface.At a wireless receiver end, as a cellular basestation, all overlapping signals that cover institute's allocated frequency band are received together.Encoded signals (Fig. 5 (a)-(c)) added together forms a composite signal waveform (Fig. 5 (c)) separately.

After receiving signal demodulation is arrived suitable base band frequency, just composite signal is decoded.Composite signal (Fig. 5 (c)) that receives and the condition code (Fig. 5 (d)) that was used for modulation signal 1 are originally multiplied each other and information signal 1 can be decoded or despreading.The signal that analysis result produces can be determined the polarity (high/low ,+1/-1, " 1 "/" 0 ") in each information bit cycle of signal.How the code generator of receiver is accomplished and sends the synchronous details of sign indicating number to belong to prior art.

Average voltage or the most magnitude of voltage that can get each sheet polarity in each bit period judge.Signal do not occurring in ambiguous time, the processing method that this " firmly " judged is an acceptable.For example, in the 1st bit period of the signal shown in the figure (f), sheet mean value is+1.00, and this value can show that fully a bit polarity is+1.Similarly, between the 3rd bit period, sheet mean value is+0.75, this bit polarity also is approximately+and 1.But between second bit period, sheet mean value is 0, and most magnitude of voltage or average test all can not provide an acceptable polarity number.

Under this ambiguous case, must determine bit polarity with " soft " determination methods process.For example, an aanalogvoltage that is directly proportional with the signal that receives behind the spread spectrum can be synthesized on the several cycles corresponding to an information bit.Clean synthetic result's polarity and symbol show bit value be+1 or-1.

The decode procedure of signal 2 is similar to signal 1, by Fig. 6 (a)-(d) expression explanation.But after decoding the ambiguous situation of bit polarity does not appear.

In theory, this decoding mechanism goes for decoding and forms each signal of composite signal.Very ideally, if when digital spread spectrum sign indicating number and undesirable signal in orthogonal, the influence of these undesirable interference signals has just minimized.(if two binary sequences just in time then are not quadrature simultaneously in every half-bit position).Regrettably, only having the several orthogonal sign indicating number in certain given word length exists.Another problem is that the prerequisite that keeps quadrature is the relative time calibration that must strictly keep between two signals.Under the roving communication environment in portable radiotelephone unit, for example in cellular system, the precise time calibration is difficult to reach.In the time can not guaranteeing coded orthogonal, noise signal just may be disturbed with the actual bit sequence that various coding maker such as mobile phones are produced.But, compare with the energy of orthogonal intersection code signal, the energy of noise signal is very little usually.

" processing gain " is a parameter of spread spectrum system, and for a direct spread system, it is defined as the ratio of spread spectrum or coding bit rate and basic information bits rate, that is, and and the sheet number that each information bit or symbol are contained.Like this, processing gain is actually bandwidth expansion ratio, i.e. the ratio of the bandwidth of spreading code and information signal.Coding bit rate is high more, and the information spread spectrum must be wide more, and then spreading ratio is just big more.For example, modulate the code signal of per second 1 megabit with per second 1Kbit information rate, then processing gain is 1000: 1.For example, processing gain shown in Figure 4 is 8: 1, is the ratio between coded slice rate and the inter-area traffic interarea bit rate.

Big processing gain has reduced the chance of decoding with the noise signal of uncorrelated sign indicating number modulation.For example, processing gain militarily can be used for measuring enemy's interference signal inhibition.In other environment, for example in the cellular system, processing gain can be used to suppress other and be in same communication channel at present and use friendly signal with the incoherent coding of desirable coding.When mentioning subtraction CDMA demodulation techniques, " noise " comprises enemy and friendly square signal simultaneously, may be defined as any uninterested signal, interested signal refer to the signal that will decode.Above-mentioned example is enlarged, and is 10: 1 if wish the ratio of signal and interference, and processing gain is 1000: 1, and traditional cdma system has the ability that the signal that allows maximum 101 homenergics is shared same channel.In decode procedure, 100 in 101 signals are suppressed to 1/1000 of their original interference powers.So total interfering energy is 100/1000, or 1/10, compare with desirable unit information energy.Because the information signal energy is bigger 10 times than interfering energy, can accurately find corresponding information signal.

Processing gain has determined the number of the overlapped signal that can allow on the same channel with the signal-interference ratio of hope.By reading, can recognize that as the above-mentioned people's such as Gilhousen that quote paper this is still the cdma system traditional view of restriction easily.

Contrast with traditional CDMA, an important feature of subtraction CDMA demodulation techniques is to recognize that inhibition to friendly CDMA signal is not to resemble the restriction of the processing gain that suppresses to be subjected to the military types of interference signal extended frequency demodulator.In the composite signal that receives, have most other signal be not can not be correlated with not with interference signal or ambient noise.On the contrary, the great majority of above-mentioned noise are as can be known, and be used for auxiliary to the decoding of interested signal.These most of noise signals be characterized as this fact as can be known, comprise their corresponding spreading codes, in subtracting each other the CDMA demodulation techniques, be used to improve the accuracy of the capacity and the decode procedure of system.Be not only from composite signal, each information signal to be decoded simply, subtract each other the CDMA demodulation techniques and also after to each information signal decoding, it is separated from composite signal.Remaining signal is as long as decoded from remaining composite signal.The signal of therefore, having decoded can not cause interference to the decoding of residual signal.

For example, in Fig. 7, if signal 2 is decoded as figure (a), the coding form of signal 2 can re-construct to figure (b) and the form (c) (the 1st bit period of the data flow that re-constructs of signal 2 initial with Fig. 4 (d) and the initial adjustment that is as the criterion of the 4th sheet of the coding of the signal 2 (e)), from the composite signal of figure (d), cut then, (equally with the 1st sheet of the code signal 2 that re-constructs with adjustments that be as the criterion of the 4th sheet of the composite signal that received) stays encoded signals 1 and scheming (e).This point is easy to be confirmed by comparison signal Fig. 7 (e) and Fig. 4 (c) (preceding 3 and last sheet cut out).Just can restoring signal 1 by encoded signals 1 is multiplied each other reconstruction signal 1 with sign indicating number 1.Please note, because the bit period of the data flow of signal 1 and 2 is offset 2 sheets mutually, in the 1st bit period of the signal 1 of the recovery shown in Fig. 7 (f), has only 6+1, it is important, traditional CDMA coding/decoding method can not determine the polarity of the information bit of the 2nd bit period of signal 1 among Fig. 5 (f) be+1 or-1, and the coding/decoding method of subtraction CDMA demodulation techniques has only just solved this ambiguous problem by isolate signal 2 from composite signal simply effectively.

Now introduce a common cdma system in conjunction with Fig. 8 (a) and (b).In the transmitter shown in Fig. 8 (a), information source such as language convert digital form to by analog form in a traditional source encoder 20.The digitlization bit stream that transmitter source encoder 20 produces is further handled by transmitter error correcting encoder 22, and 22 add redundancy, and bandwidth being increased or transmit bit rate increases.For response by a suitable controlling mechanism for example a spreading code producing of programmable microprocessor (not shown) select signal, send spectrum-spreading code generator 24 by one and generate a special spread spectrum coding; 24 can be a pseudo random number word generator.Selected spreading code and encoded information signal addition in modulo 2 adder 26 of exporting by error correcting encoder 22.The mould 2 that should be understood that two binary sequences adds and is actually a binary logic xor operation.These mould 2 summations become one group " sheet " with each bit information " expansion " of encoder 22 outputs effectively.

Code signal by adder 26 outputs is used for modulating a RF carrier wave by certain modulation technique such as QPSK in modulator 28.Carrier wave after the modulation is sent from air interface by a traditional radio transmitters 30.The a plurality of code signals that overlap the frequency band that is distributed are received down together in the form of wireless receiver 32 with a composite signal waveform, and 32 can be a cellular radiotelephone base stations, as Fig. 8 (b).Through modulator 34 separate be transferred to base band after, composite signal is decoded.

Decoding or " despreading " to certain independent information signal are to obtain by composite signal is multiplied each other with the feature spreading code that is produced by receiver spreading code maker 36 accordingly.This condition code is corresponding to originally being used for the spreading code of this information signal of spread spectrum sending spreading code maker 24 ends.Signal after this spreading code and the demodulation is mixed by multiplier 38.Because several some bits of representing transmission information that receive, the output signal of multiplier 38 want continuous sheet to one group of given number to synthesize accumulative total to obtain the actual value of information bit.As mentioned above, the judgement of these bit values can be by averaging to the sheet polarity in each bit period or the method for most magnitudes of voltage is carried out.Under any circumstance, the output signal of multiplier 38 finally all will be added on the receiver error correction decoder 40,40 inverse operations of the processing of transmitter error correcting encoder 22 just, and the digital information that obtains converts analog form (as speech) to by source decoder 42.

As mentioned above, this decoder is built in going in theory each signal decoding in the composite signal.Ideally, when the undesirable interference signal quadrature of digital spread spectrum sign indicating number and those and under the relative time between these signals keeps strict situation, the influence of interference signal just is reduced to very little.But regrettably, in certain limited word length, only have the several orthogonal sign indicating number and exist, and under the constantly mobile communication environment in portable radiotelephone unit, for example cellular system is difficult to reach time calibration.

In a preferred cdma communication system, error correction coding is based on the information that will send is carried out quadrature or biorthogonal block encoding.In the quadrature block encoding, one group of bit M that send is converted into 2 ^M Individual 2 ^MOne of-bit orthogonal code.Decoding to an orthogonal code relates to and set N=2 ^MAll members' is relevant in the code word.Provide the highest relevant code word binary system index and produce into needed information.For example, if label be 0-15 16 16-bit codewords to be correlated with the 10th 16-bit codewords be maximal correlation, then information signal is 4-bit binary code word 1010 (a metric integer 10, index is 10 here).A coding so also is designated as [16, a 4] orthogonal block code, and has spread spectrum rate R=16/4=4.Reverse by all bits, can obtain the next bit information of each codeword information code word.Such coding is the biorthogonal block encoding.

A key character of this coding is, to relevant can the realization by quick Wal scholar's conversion (FWT) equipment in all orthogonal block code words in a set.The signal of spread spectrum coding comprises a plurality of [128,8] or a plurality of [128,7] Wal Shi-Ha Demode code word.For example, one [128,7] block codewords, 128 input signal samplings are transformed into one 128 Wal scholar's frequency spectrums, the correlation of a code word during each point is represented an input signal sampling and gathered in the frequency spectrum, although using FWT is effective method more, also can disposes a codified digital signal processor easily and calculate the Wal scholar and change.A suitable FWT processor is introduced in the 07/735th, 805 (filing on July 25th, 1991) of the common U.S. of transfer patent application to some extent, quotes here only to be reference.

In a preferred embodiment of the present invention, signal of communication at first is encoded into the 7-bit byte, uses [128, a 7] quadrature Wal Shi-Ha Demode block code further to encode to produce the 128-bit codewords then.The nodulo-2 addition institute scramble that the code word of each distinctive signal is sheltered by the distinctive scramble of each signal.The mode of code word after the scramble by filtering and modulation by bit serial send.An optimum decision system is in U.S. patent application the 07/866th, 865, in filing on April 10th, 1992, title is introduced to some extent for " multi-address coding that is used for mobile radio telecommunications " literary composition.

Being preferably in the identical channel of first digit signal processor 110 usefulness finishes the filtering of all signals and converts I, Q modulation waveform to.I, Q waveform and a weighted factor that depends on the relative signal intensity that each signal will send are added together then, because it is logical and useful should sending signal with higher signal intensity for the far mobile radio station of distance, and for the nearer mobile radio station in the distance base station signal strength signal intensity transmission signal that then usefulness is lower.Exported to by the first digit signal processor before D/A converter 112,113 carries out quadrature modulation by quadrature modulator 114 subsequently, I, Q waveform must be proofreaied and correct through above-mentioned correction factor after the addition.Not calibrated I, Q value are sent into second digit signal processor 125 by first digit signal processor 110 output too and are used for estimating that with modulation the definite measured value of receiver compares.

In this preferred implementation method, be used to receive that receiver by the compound CDMA signal of base station adopts above-mentioned introduction or the U.S. patent quoted and the subtraction CDMA technology of patent application.Each mobile radio station is at first sheltered with the scramble of maximum intensity signal and is gone the method for scramble that it is decoded to the strongest orthogonal intersection code signal, carry out a 128-point, FWT, and in the 128 conversion compositions of determining to detect maximum one and detect which yard most probable and be sent out.Cut the code word that has detected then from composite signal, for example, this can be set to 0 by the transform component of maximum, carries out a 128-point and instead adds your assorted conversion (IFWT) fast, uses disturbing code at last again.Use the scrambling code that goes to repeat said process continuously to the composite signal of remainder, till mobile radio station with signal decoding is its desired form corresponding to next peak signal.Can prevent that in this way stronger signal from hindering the decoding than weak signal to they covered.

When a signal is cut, cut corresponding to a perfect modulated waveform in theory, remainder has stayed the defective in the modulated process.According to the preferred embodiment of invention, a subtraction CDMA receiver is used as the modulation of proofreading and correct the transmitter modulates defective and estimates receiver.Further, correction factor can directly be represented by the transform component that FWT produces with some.

Be used for serial send 128-than the modulator approach of the Wal Shi-Ha Demode code word of bit scrambling preferably the shaping offset quadrature amplify modulation (SOQAM), its relevant part with OQPSK is, the even bit bit is used for the I phase place and the odd bits bit is used for the Q phase place.The sampled point that is used for SOQAM has shown at I shown in Figure 9, Q waveform.Sampled point desired among Fig. 9 is by the definite clock signal f that is produced by reference frequency and time generator 121 of a traditional method ₅, f ₆Feature.OQPSK has further argumentation in above-mentioned S.Gronemeyer work literary composition.

At receiver end, signal sampling must alternately be obtained by I, Q channel on principle, with the 128-sampling block (representing in 128 128-bit Wal Shi-Ha Demode block codewords) that obtains carrying out the FWT conversion thereon.But, by being increased progressively 90 ° the order of magnitude by each bit period, received signal carries out the phase place pre-rotation, then the rotation of the phase place of even bit bit is 0 ° or 180 °, this just makes the even bit bit at the I channel, though there is the even bit bit of half to be inverted, and the phase place half-twist of odd bits bit or 270 °, this makes the odd number bit forward the I channel to from the Q channel.Through such pre-rotation, all 128 samplings that are used for the FWT conversion are all collected from same channel (being the I channel in this example).The effect of pre-rotation is will be according to pattern ++--++--++--... change the symbol of sampling, this pattern is Wal Shi-Ha Demode benchmark code word WZ.Therefore, by means of the numerical characteristic of Wal Shi-Ha Demode code word, detected code word contains a mould 2 by turn and adds 2 side-play amount with respect to the code word that sends.The method that can be at an easy rate cuts side-play amount 2 by mould 2 is by turn proofreaied and correct detected code word.For example, if send decimal data piece 73 (binary number is 01001001) with 128-bit Wal Shi-Ha Demode code word W 73, then because the pre-rotation effect can detect data block 75 (binary number 01001011), binary number 0,000,001 0 mould 2 by turn adds, and has just proofreaied and correct the data bit of counter-rotating.

Carrier wave leakage loss or I, Q skew can occur with the form of a constant carrier component in the signal that sends in the quadrature modulator, this constant is corresponding to the Wal Shi of scramble-Ha Demode code word W O not, but because pre-rotation, this carrier wave leakage loss composition is converted into corresponding to the Wal Shi-Ha Demode code word W 2 without scramble.Like this, can carry out a FWT conversion then, and the method that transform component 2 is designated the equilibrium imbalance of modulator is detected such leakage loss or skew by composite signal being gone scramble with an empty scrambling code.This transform component, possible more complicated is comprising the random phase of being introduced by transmission path, and this can get rid of by it is closed the method for linking the known phase that sends one of signal.

In an optimum decision system, in the overlapped signal the strongest one as with broadcasting (callings) channel of all mobile station communicates, also as a pilot tone or phase place-reference signal, make the phase place of other signal and the above-mentioned balanced imbalance measurement can be associated.Especially, if the complex values of the detected transform component of maximum is S1 when peak signal is decoded, the plural number that the measurement result of the W2 transform component of representing the balanced imbalance of modulator is obtained is K, and I, Q leakage loss composition Ki and the Kg that returns to first digit signal processor 110 as correction factor provided by following formula so:

Ki+iKg=S1*K=(Re(S ₁)-iIm(S ₁))(Re(K)+iIm(K))。

For the relative conversion error of I, Q channel, if the I channel modulator produces a signal bigger than Q channel modulator, then originally should should be less than the signal sampling that inserts by the I channel in the amplitude of the signal sampling of Q channel.This is equivalent to increases an a small amount of pseudo codeword that is not used in correct code word with the Q bit inversion, thereby produces very little a destructiveness stack and the very little enthusiasm stack to the I bit to the Q bit.So this pseudo codeword be by with pattern of symbol+-+-+-+-+-+-+-... the modification that sends code word is obtained, and this pattern is the basic code word W1 of Wal Shi-Ha Demode.Therefore, be mathematical characteristic equally by means of Wal Shi-Ha Demode code word, this pseudo codeword with respect to the code word that sends have one by turn mould 2 add 1 side-play amount.Therefore, by determine sending the composition of the Wal Shi-Ha Demode conversion 1 outside the code word, the conversion error of I, Q interchannel just can be identified and be obtained correction.

Can find that this very little pseudo-component can be masked by the pseudo-component that produces because of other signal at an easy rate, if but these become at first decoded and cut, and this minor error component can be detected more easily.Moreover, can after to each overlapped signal decoding, carry out with respect to the independent estimation of the value of the component of the relative conversion mistake of I, the Q of main decoder code word for representative.Then can ask on average from the code word of 128 signal sampling pieces decoding at all, can on many blocks, ask average equally, thereby on average go out otherwise will shield to represent I, the Q above-mentioned pseudo-error source of the small component of mistake conversion relatively these values.

With the synchronous average weight of the detected transmission code word representative wrong factors A that converts, and be used for correcting the correction factor T of the mistake in 90 ° of phase split networks 103 of quadrature modulator with the component representative that detects the code word quadrature.Like this, if the information of using Wal scholar's figure signal decoder to provide neatly, then all mistakes can be determined and send corresponding correction factor to be used to modulate first digit signal processor 110 in the quadrature modulator, so that it takes above-mentioned error correction.Just may guarantee fully that by this way the complex modulated that produced by the base station accurately is consistent with desired theoretic waveform.

Although introduced, will be appreciated that the present invention is the restriction of claims about some specific implementation method of the present invention.Might make an amendment because be proficient in the personnel of technology, current application all estimates any modification within the spirit and scope of the present invention of being issued with require interior again.

Claims (25)

1. be used for accurately forming adaptively precompensating quadrature modulator, comprise through modulation signal:

First processor applies a correction factor to the not correction of in-phase modulation waveform and quadrature modulation waveform sampling, thereby produces calibrated sampling, and calibrated sample conversion is become calibrated in-phase modulation waveform and quadrature modulation waveform;

Quadrature modulator applies an in-phase modulation waveform to the carrier wave of cosine in fact, and applies calibrated quadrature modulation waveform to being actually sinusoidal carrier wave, thereby produces modulated signal;

Receiver is estimated in the modulation that is connected on the quadrature modulator, produces the digitized sampling through modulation signal; With

Be connected to first processor and modulation and estimate second processor of receiver, determine correction factor according to digitized sampling and not calibrated sampling, and send correction factor to first processor.

2. according to the adaptively precompensating quadrature modulator of claim 1, it is characterized in that comprising:

A quadrature modulator, be used for being applied with a calibrated in-phase modulation waveform on the carrier wave of cosine waveform actually, and for being applied with a calibrated quadrature modulation waveform on the sinusoidal wave carrier wave, quadrature modulator produces a modulated output signal actually;

Sender device, be used for modulated output signal up-conversion of above-mentioned quadrature modulator and be amplified to a predetermined transmission frequency and power level, sender device produces modulated transmission signal, and comprises that at least one is by the frequency mixer that drives and carry out the modulated signal of up-conversion from the signal of frequency synthesizer;

Receiving system is estimated in modulation, be connected on the above-mentioned sender device, be used to produce the digitlization sampling of modulated transmission signal, described modulated transmission signal is by the frequency mixer down-conversion that is driven by the signal from the frequency synthesizer, modulation estimation receiving system is operated in the mode that is different from quadrature modulator, to measure homophase and the orthogonal signalling that produce by sender device, wherein modulation estimates that receiving system can comprise an amplifier, described amplifier produces an output signal and a hard restriction phase signal that offers the phase digitization device that approximately is proportional to the logarithm of its input signal amplitude, and described phase digitization device can be included in modulation and estimate in the receiving system; With

Second digital signal processing device, communicate by letter with described first digital signal processing device and described modulation estimation receiving system, be used for according to estimate by described modulation described digitlization sampling that receiving system produces and not calibrated sampling determine to proofread and correct because of, and send correction coefficient to first digital signal processing device.

3. the described adaptively precompensating quadrature modulator of claim 1, wherein said first digital signal processing device comprises at least one D-A converter, is used for calibrated sample conversion is become by above-mentioned quadrature modulator to be added in above-mentioned homophase and quadrature modulation waveform on the above-mentioned carrier wave.

4. the described adaptively precompensating quadrature modulator of claim 3, wherein said D-A converter adopt the in fact δ-∑ modulation method of height over-sampling.

5. the described adaptively precompensating quadrature modulator of claim 1, wherein above-mentioned modulation estimate that above-mentioned digitized sampling that receiving system produces alternately comprises the sampling of polar coordinates or log-polar form.

6. the described adaptively precompensating quadrature modulator of claim 5, wherein said second digit signal processing apparatus estimates that with above-mentioned modulation the digitized sample conversion that receiving system produces becomes cartesian form.

7. the described adaptively precompensating quadrature modulator of claim 1, wherein said homophase and quadrature modulation waveform comprise a spread spectrum code signal.

8. the described adaptively precompensating quadrature modulator of claim 7, wherein, the signal of above-mentioned spread spectrum coding comprise a plurality of second spread spectrum coded signal and.

9. the adaptively precompensating quadrature modulator of claim 8, wherein above-mentioned second digit signal processing apparatus comprise carries out Wal scholar's conversion to determine the device of above-mentioned correction factor.

10. the described adaptively precompensating quadrature modulator of claim 8, wherein above-mentioned second spread spectrum coded signal comprises a plurality of [128,7] Wal Shi-Ha Demode code word.

11. the described adaptively precompensating quadrature modulator of claim 8, the signal of wherein above-mentioned second spread spectrum coding comprise a plurality of [128,8] Wal Shi-Ha Demode code word.

12. the described adaptively precompensating quadrature modulator of claim 1, wherein above-mentioned second digit signal processing apparatus comprise that one is carried out Wal scholar's conversion to determine the device of above-mentioned correction factor.

13. the described self-adaptive modulator of claim 1, wherein above-mentioned modulated output signal comprises a Quadrature Phase Shift Keying signal, an offset quadrature phase-shift-keying signal, a shaping offset quadrature phase keying signal, a quadrature amplifies modulation signal, offset quadrature amplifies modulation signal, and shaping offset quadrature amplifies one in the modulation signal.

14. be used for accurately forming the adaptively precompensating quadrature modulation method of modulated signal, comprise the steps:

(a) one group correction factor is added on uncorrected homophase and the quadrature modulation waveform sampling, to produce the homophase and the quadrature modulation sampling of proofreading and correct;

(b) form calibrated in-phase modulation waveform from the in-phase modulation sampling of having proofreaied and correct, and with carrier wave that is actually cosine wave of the in-phase modulation waveform modulated of having proofreaied and correct, the calibrated quadrature modulation waveform of formation from the quadrature modulation of having proofreaied and correct sampling, and be actually sinusoidal wave carrier wave, and by modulated cosine carrier is formed modulated output signal mutually with sinusoidal carrier with this of calibrated quadrature modulation waveform modulated;

(c) by will this modulated output signal up-conversion and be amplified to a transmission frequency that choose, desired and power level, form modulated transmission signal;

(d) collect the digital sample of this modulated transmission signal;

(e) determine the correction factor group from described digital sample and not calibrated sampling.

15. the described method of claim 14 wherein forms step (b) and comprises that with above-mentioned calibrated homophase and orthogonal waveforms sample conversion be the such step of analog form.

16. the method for claim 15, wherein above-mentioned conversion step comprise the in fact δ-∑ modulation method of height over-sampling.

17. the described method of claim 14, wherein above-mentioned digitized sampling alternately comprises polar coordinates and log-polar representation.

18. the described method of claim 17, wherein step (c) comprises that alternately the representation with polar coordinates and log-polar converts the such step of Descartes's representation to.

19. the described method of claim 14 wherein comprises the signal of a spread spectrum coding through modulated output signal.

20. the described method of claim 19, wherein step (e) is included in and carries out Wal scholar's conversion on the above-mentioned digitized sampling to determine the such step of above-mentioned correction factor.

21. the described method of claim 19, wherein the signal of above-mentioned spread spectrum coding comprises a plurality of [128,7] Wal Shi-Ha Demode code word.

22. the described method of claim 21, wherein above-mentioned spread-spectrum signal comprise a plurality of [128,8] Wal Shi-Ha Demode code word.

23. the described method of claim 14, above-mentioned modulated output signal comprises a Quadrature Phase Shift Keying signal, an offset quadrature phase-shift-keying signal, a shaping offset quadrature phase-shift-keying signal, a quadrature amplifies modulation signal, offset quadrature amplifies modulation signal, and in shaping offset quadrature am signals one.

24. in the described method of claim 14, wherein step (e) is included in and carries out Wal scholar's conversion on the above-mentioned digitized sampling, to determine the such step of above-mentioned correction factor.

25. according to the adaptively precompensating quadrature modulator of claim 24, wherein first processor comprises at least one D-A converter, and calibrated sample conversion is become calibrated in-phase modulation waveform and quadrature modulation waveform.

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