US20020064236A1 - Transmission apparatus - Google Patents

Abstract

Nonlinear distortion compensating data is calculated by approximation equations at a compensating coefficient calculation section using an amplitude value of transmission quadrature base band signals obtained by a power calculating section, wherein by carrying out nonlinear distortion compensation at a nonlinear distortion compensating section using the data, it is possible to compensate nonlinear distortion generated in an amplifier of the transmission system without use of any memory table, and a nonlinear distortion compensating section can be obtained, which has a great effect of decrease distortion.

Description

TECHNICAL FIELD
• The present invention relates to a nonlinear distortion compensating technique in a transmission apparatus for digital radio communications.[0001]
BACKGROUND ART
• In recent years, a mobile communication system using a digital modulation method has vigorously been researched and developed. If a high efficiency amplifier is employed in the transmission system in order to attempt to save power at a radio transceiver, nonlinear distortions frequently result therefrom. As a means, there is a method for compensating nonlinear distortions of amplitude and phase with reference to a distortion compensating table, by using an amplitude value of transmission base band signals.[0002]
• A description is given of a conventional transmission apparatus which compensates nonlinear distortions by using such a method.[0003]
• FIG. 10 is a main block diagram of a conventional transmission apparatus. In FIG. 10,[0004]amplitude calculating section1001 calculatesamplitude information1010 of transmission signals1009 (transmission digital quadrature base band of I and Q channels), and compensation table1002 outputsdistortion compensating coefficient1011. Thedistortion compensating section1003 outputs a distortion compensating signal1012 according to thetransmission signal1009 anddistortion compensating coefficient1011. The outputted distortion compensation signal1012 is quadrature-modulated by quadrature modulatingsection1004, and the modulatedsignal1013 is amplified byamplifier1005, wherein amplifiedRF signal1014 is outputted.
• Furthermore, demodulating[0005]section1007 demodulatesfeedback RF signal1016 fed back fromcoupler1006 to feedbackbase band signal1017, and estimatingsection1008 updates the distortion compensation coefficient of compensation table1002 on the basis of adistortion compensation coefficient1018,transmission signal1009 and feedbackbase band signal1017. Through the abovementioned actions, amplifiedRF signal1015 for which nonlinear distortion compensation is carried out is outputted from thecoupler1006.
• In addition thereto, as a method to compensate nonlinear distortions in the transmission system, there is a method having a digital filter to which a ROM (Read-only-memory) is attached, wherein compensation is carried out by applying in advance distortions to compensate nonlinear distortions generated in an amplifier by the digital filter.[0006]
• The main block diagram of a conventional transmission apparatus in which this method is employed is shown in FIG. 11. Hereinafter, a description is given to this apparatus.[0007]
• In FIG. 11,[0008]digital filter1102 in whichdigital signals1101 is inputted gives to thedigital signal1101 distortions to compensate nonlinear distortion components generated in radiofrequency power amplifier1105, by using distortion information stored in a ROM in advance.
• The[0009]digital signal1101 to which distortion to be compensated is given is digital-analog converted and modulated by quadrature modulatingsection1103 and inputted into the radiofrequency power amplifier1105 viatransmission section1104. In the radiofrequency power amplifier1105, since distortion of the inputted digital signal are compensated in advance, distortions generated at the radiofrequency power amplifier1105 are cancelled by those for compensation.
• Furthermore, instead of ROM, there is still another method to compensate nonlinear distortions, in which a RAM (Random Access Memory) having compensation coefficients stored therein in order to compensate nonlinear distortion components is used, by varying the compensation coefficients of the RAM in compliance with amplitudes of digital signals.[0010]
• Furthermore, Unexamined Japanese Patent Publication No. 290321 of 1992 discloses a method for controlling actions of a digital filter by feeding outputs of a radio frequency power amplifier back to the digital filter.[0011]
• However, in the conventional example shown in FIG. 10, it is necessary that signals having the maximum amplitude is suppressed less than the maximum output of[0012]amplifier1005, and this results in a lowering of efficiency in theamplifier1005.
• In the conventional example shown in FIG. 11, since it is necessary to provide a memory table such as a ROM or RAM in which compensation coefficients are stored to compensate nonlinear distortion components, and this results in an increase of the scale of transmission circuits themselves.[0013]
DISCLOSURE OF INVENTION
• It is therefore an object of this invention to provide a transmission apparatus capable of easily controlling leak power and easily improving the efficiency of power amplification and cable of compensating nonlinear distortions generated in a transmission system amplifier without any use of a memory table such as a ROM or RAM.[0014]
• The first aspect of the invention resides in a transmission apparatus having a nonlinear distortion compensating circuit, which includes an amplitude limiting function for transmission quadrature base band signals by adding an amplitude calculating section, an amplitude limiting table and an amplitude limiting section thereto. Thereby, it is possible to easily improve the efficiency of amplification section with distortions of the entire system limited.[0015]
• The second aspect of the invention is such that nonlinear distortion compensation is carried out on the basis of nonlinear distortion compensation coefficients calculated by an approximation equation in a compensation coefficient calculating section. Thereby, it is possible to compensate nonlinear distortions generated by amplifier in the transmission system without any use of a memory table such as a ROM or RAM, and it is possible to make a nonlinear distortion compensating section small-sized.[0016]
• Furthermore, this invention is constructed so that it is provided with a first amplitude calculating section for calculating the first amplitude value of transmission quadrature base band signals; an amplitude limiting table for storing amplitude limiting information corresponding to the first amplitude value; a first amplitude limiting section for limiting the amplitude of the transmission quadrature base band signals by using the amplitude limiting information; a quadrature modulating section for outputting RF signals by quadrature-modulating the transmission quadrature base band signals, the amplitude of which is limited; and an amplification section for amplifying the RF signals.[0017]
• With this construction, it is possible to improve the efficiency of an amplifying section with distortion components limited, by executing distortion compensation of an amplifier with respect to limited signals, the maximum amplitude of which is distorted by the transmission quadrature base band signals.[0018]
• Furthermore, the invention is constructed so that it is provided with a first amplitude calculating section for calculating the first amplitude value from transmission quadrature base band signals; a limiting coefficient calculating section for calculating an amplitude limiting coefficient corresponding to the first amplitude value; a second amplitude limiting section for limiting the amplitude of the transmission quadrature base band signal by using the amplitude limiting coefficient; a quadrature modulating section for quadrature-modulating the transmission quadrature base band signals to output RF signals, the amplitude of which is limited; and an amplification section for amplifying the RF signals.[0019]
• With this construction, the amplitude limiting coefficient is calculated on the basis of amplitude information of the transmission quadrature base band signals, whereby it is possible to improve the efficiency of amplifier by limiting the amplitude of transmission signals in compliance with the amplitude limiting coefficient with the distortion components limited, without adding any memory thereto.[0020]
• Furthermore, this invention is constructed so that it is provided with a power calculating section for calculating a power value of transmission quadrature base band signals; a compensation coefficient calculating section for calculating a nonlinear distortion compensation coefficient according to approximation equation set in advance using the power value; a distortion compensating section for carrying out nonlinear distortion compensation of the transmission quadrature base band signals by using the nonlinear distortion compensation coefficient; a quadrature modulating section for quadrature-modulating transmission quadrature base band signals, the distortion of which is compensated; and an amplifier for amplifying the quadrature modulation signal.[0021]
• With this construction, with only slight memory capacity, it is possible to compensate nonlinear distortion which is generated at an amplifier of transmission system.[0022]
• Furthermore, the invention is constructed so that it is provided with a power calculating section for calculating a power value of transmission quadrature base band signals; a compensation coefficient calculating section for calculating an amplitude distortion compensation coefficient by an approximation equation set in advance by using the power value; a quadrature modulating section for quadrature-modulating the transmission quadrature base band signals; and an amplitude distortion compensating section for compensating amplitude distortions of quadrature modulation signals using the amplitude distortion compensation coefficient.[0023]
• With this construction, it is possible to compensate amplitude distortions, which is generated at an amplifier of transmission system, with simple calculations and slight memory capacity.[0024]
• Furthermore, the invention is constructed so that it is provided with a power calculating section for calculating a power value of transmission quadrature base band signals; a compensation coefficient calculating section for calculating an amplitude distortion compensation coefficient by an approximation equation set in advance by using the power value; a quadrature modulating section for quadrature-modulating the transmission quadrature base band signals; an amplitude distortion compensating section for compensating amplitude distortions of quadrature modulation signals by using the amplitude distortion compensating coefficient; an amplifier for amplifying modulation signals; a distributor for distributing output of the amplifier; a quadrature demodulator for carrying out quadrature demodulate with one of the outputs of the distributor inputted; and a coefficient updating section which calculates an error by comparing quadrature demodulate signals with the power value and updates the value of coefficients of the approximation equation on the basis of the error.[0025]
• With this construction, it is possible to very accurately compensate amplitude distortions by lowering the error of amplitude distortion compensation data calculated by an approximation equation through a feedback loop.[0026]
BRIEF DESCRIPTION OF DRAWINGS
• FIG. 1 is a main block diagram of a transmission apparatus according to a first embodiment of the invention,[0027]
• FIG. 2 is a main block diagram of a transmission apparatus according to a second embodiment of the invention,[0028]
• FIG. 3 is a main block diagram of a transmission apparatus according to a third embodiment of the invention,[0029]
• FIG. 4 is a main block diagram of a transmission apparatus according to a fourth embodiment of the invention,[0030]
• FIG. 5 is a main block diagram of a transmission apparatus according to a fifth embodiment of the invention,[0031]
• FIG. 6 is a main block diagram of a transmission apparatus according to a sixth embodiment of the invention,[0032]
• FIG. 7 is a main block diagram of a transmission apparatus according to a seventh embodiment of the invention,[0033]
• FIG. 8 is a main block diagram of a transmission apparatus according to a eighth embodiment of the invention,[0034]
• FIG. 9 is a main block diagram of a transmission apparatus according to a ninth embodiment of the invention,[0035]
• FIG. 10 is a main block diagram of a conventional transmission apparatus, and[0036]
• FIG. 11 is a main block diagram of another conventional apparatus other than the above apparatus.[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
• Hereinafter, a detailed description is given of embodiments of a transmission apparatus according to the invention.[0038]
• (Embodiment 1)[0039]
• FIG. 1 is a main block diagram of a transmission apparatus according to a first embodiment of the invention.[0040]
• A transmission apparatus illustrated in FIG. 1 comprises first[0041]amplitude calculating section101, amplitude limiting table102,amplitude limiting section103, nonlineardistortion compensating section104,quadrature modulating section108,amplification section109, etc.
• Nonlinear[0042]distortion compensating section104 has secondamplitude calculating section105, compensating table106 using a RAM,distortion compensating section107,coupler110, demodulatingsection111, and estimatingsection112.
• Furthermore, in FIG. 1,[0043]reference number113 indicate a transmission signal (Transmission digital quadrature base band signal in I and Q channel),reference number114 indicate amplitude information of the transmission signal,reference number115 indicate an amplitude limiting coefficient,reference number116 indicate an amplitude limiting signal,reference number117 indicate limiting amplitude information,reference number118 indicate a distortion compensation coefficient,reference number119 indicate a distortion compensation signal,reference number120 indicate an RF signal,reference number121 indicate an amplitude RF signal,reference number122 indicate an output signal,reference number123 indicate a feedback RF signal,reference number124 indicate a feedback base band signal, andreference number125 indicate a coefficient updating signal.
• A description is given of the actions of a transmission apparatus constructed as described above.[0044]
• The first[0045]amplitude calculating section101 calculatesamplitude information114 on the basis oftransmission signal113 and outputs it. In amplitude limiting table102, proper amplitude limiting information is stored in advance with respect to a modulation method designed on the basis of noise margin and leak power value as its entirety, andamplitude limiting coefficient115 is outputted in response toamplitude information114.
• [0046]Amplitude limiting section103 limits the amplitude oftransmission signal113 in accordance with theamplitude limiting coefficient115 and outputs anamplitude limiting signal116 thus obtained. The amplitude limiting executed herein is to limit the protrudent amplitude in only a slightly short time. Furthermore, it is clear that the leak power ofamplitude limiting signal116 can be designed in advance on the basis of a modulation method and amplitude limiting information.
• Nonlinear[0047]distortion compensating section104 compensates nonlinear distortions ofamplifier109 almost as in the description with reference to FIG. 10 in the conventional example.
• That is, the second[0048]amplitude calculating section105 calculates limitingamplitude information117 fromamplitude limiting signal116 and outputs it. Compensation table106 outputsdistortion compensation coefficient118 in response to limitingamplitude information117.Distortion compensating section107 calculatesdistortion compensation signal119 on the basis ofdistortion compensation coefficient118 andamplitude limiting signal119.Quadrature modulating section108 modulatesdistortion compensation signals119 to radio frequency (RF) signals120 which are signals of carrier band.Amplifier109 amplifies the power of RF signals120 and outputs amplified RF signals121.
• Coupler[0049]110 outputs a part of amplified RF signals121 as afeedback RF signal123 and outputs the remaining thereof as output signals122.Demodulator111 demodulates the feedback RF signal123 to a feedbackbase band signal124. Theestimating section112 updates, using theamplitude limiting signal116 as a target value, distortion compensation coefficients stored in the compensation table106 by acoefficient updating signal125 in compliance with adistortion compensation coefficient118 read by thecoefficient updating signal125, limitingamplitude information117 and feedbackbase band signal124.
• As a result, the linearity between[0050]amplitude limiting signal116 and feedbackbase band signal124 will be retained by a distortion compensation coefficient stored in compensation table106.
• The distortion components of the[0051]output signal122 are equalized to the distortion components of theamplitude limiting signal116. As described above, theamplitude limiting signal116 can be easily designed on the basis of modulation method and the amplitude limiting information stored in amplitude limiting table102, wherein it is possible to control distortion components as the entire system by the amplitude limiting information.
• In a prior nonlinear distortion compensation technique, the maximum amplitude signal is assigned to the maximum output value of an amplifier. However, since signals having the maximum amplitude have a very low ratio of existence, they will not exert any great influence as leak power even though the maximum amplitude signals are slightly distorted. Therefore, if the amplitude of the maximum amplitude signals is limited and its average amplitude is relatively raised, it becomes possible to improve the amplification efficiency of an amplifier.[0052]
• Thus, according to the first embodiment, since the amplitude of signals having a great amplitude is limited before carrying out nonlinear distortion compensation, the maximum amplitude value is lowered, wherein the[0053]amplifier121 has an allowance to improve the mean power.
• On the other hand, distortion components, the amplitude of which is limited, can be designed in advance on the basis of its modulation system and limiting properties, the leak power resulting from the nonlinearity outside the signal band can be suppressed less than the prescribed level, wherein the area of nonlinearity of the[0054]amplifier121 is used to cause the efficiency of power amplification to be improved.
• Thus, since it is possible to easily control the distortion components, it is possible to construct a more efficient transmission apparatus than that according to the prior nonlinear distortion compensation technique.[0055]
• Generally, suppression of signals having a great amplitude is effective in improving the efficiency. However, it is also possible to secure the same effect by elongating signals having a small amplitude. Furthermore, by making the amplitude width narrow by a combination of the former and the latter, the efficiency can be further improved.[0056]
• (Embodiment 2)[0057]
• FIG. 2 is a main block diagram of a transmission apparatus according to a second embodiment of the invention. However, parts in the second embodiment illustrated in this drawing, which correspond to those of the first embodiment illustrated in FIG. 1 are given the same reference numbers, and the description thereof is omitted.[0058]
• A transmission apparatus shown in FIG. 2 is different from that shown in FIG. 1 in that, as shown at the nonlinear[0059]distortion compensating section201 of FIG. 2, the secondamplitude calculating section105 of the nonlineardistortion compensating section104 shown in FIG. 1 is omitted, andamplitude information114 of the transmission signals outputted from theamplitude calculating section101 is outputted to the compensation table106 and estimatingsection112.
• In such a construction,[0060]amplitude information114 calculated by the firstamplitude calculating section101 is outputted to the compensation table106 and estimatingsection112, and the compensation table104 outputsdistortion compensation coefficients118 in compliance with theamplitude information114.
• Furthermore, using the[0061]amplitude limiting signal116 as a target value, theestimating section112 updates the distortion compensation coefficients stored in the compensation table106 by acoefficient updating signal125 in compliance with distortion compensation coefficients read from the compensation table106 by thecoefficient updating signal125,amplitude information114, and feedbackbase band signal124. The other actions are the same as those described in the first embodiment.
• Thus, according to the second embodiment, since the nonlinear[0062]distortion compensating section201 is constructed with the amplitude calculating section omitted in addition to securing the same effects as those of the first embodiment, the configuration thereof can be further simplified than the first embodiment. The entire size thereof can be reduced.
• (Embodiment 3)[0063]
• FIG. 3 is a main block diagram of a transmission apparatus according to a third embodiment of the invention. However, parts in the third embodiment illustrated in this drawing, which correspond to those of the first embodiment illustrated in FIG. 1 are given the same reference numbers, and the description thereof is omitted.[0064]
• A transmission apparatus illustrated in FIG. 4 is different from that shown in FIG. 1 in that a limiting[0065]coefficient calculating section301 shown in FIG. 2 is provided instead of the amplitude limiting table102 shown in FIG. 1 and theamplitude limiting coefficient302 calculated by the limitingcoefficient calculating section301 is outputted to theamplitude limiting section103.
• Furthermore, a limiting[0066]coefficient calculating section301 can be achieved by a surplus calculation performance of DSP (Digital Signal Processor) (not illustrated) which is a component of the transmission apparatus along with the firstamplitude calculating section101 andamplitude limiting section103.
• In such a construction, in limiting[0067]coefficient calculating section301, a proper amplitude limiting coefficient calculation method is defined in advance with respect to a modulation system which is designed on the basis of noise margin and leak power value as the entire system, andamplitude limiting coefficients302 are outputted in compliance with theamplitude information114. Theamplitude limiting section103 calculatesamplitude limiting signals116 on the basis ofamplitude limiting coefficient302 andtransmission signal113.
• The[0068]amplitude limiting signal116 can be easily designed by a modulation system and a calculation method defined by the limitingcoefficient calculating section301, wherein it is possible to control distortion components as the entire system by the amplitude limiting coefficient calculation method. The other actions are the same as those of the first embodiment.
• Thus, according to the third embodiment, limiting[0069]coefficient calculation part301 which already exists as a component of the transmission apparatus is provided instead of the amplitude limiting table102 constructed using memories such as a ROM, etc. in addition to securing the same effects as those of the first embodiment. Therefore, it is possible to further simplify the apparatus than the first embodiment, and the entire system can be small-sized.
• (Embodiment 4)[0070]
• FIG. 4 is a main block diagram of a transmission apparatus according to a fourth embodiment of the invention. However, parts in the fourth embodiment illustrated in this drawing, which correspond to those of the third embodiment illustrated in FIG. 3 are given the same reference numbers, and the description thereof is omitted.[0071]
• A transmission apparatus illustrated in FIG. 4 is different from that illustrated in FIG. 3 in that, as shown in the nonlinear[0072]distortion compensating section201 in FIG. 4, the secondamplitude calculating section105 of the nonlineardistortion compensating section104 shown in FIG. 3 is omitted, andamplitude information114 of transmission signals outputted from theamplitude calculation portion101 is outputted to the compensation table106 and estimatingsection112.
• In such a construction, the[0073]amplitude information114 calculated by theamplitude calculating section101 is outputted to the compensation table106 and estimatingsection112, wherein the compensation table104 outputsdistortion compensation coefficients118 in compliance with theamplitude information114.
• Furthermore, using the[0074]amplitude limiting signal116 as a target value, theestimating section112 updates distortion compensation coefficients stored in the compensation table106 by acoefficient updating signal125 in compliance with the distortion compensation coefficient read from the compensation table106 by thecoefficient updating signal125,amplitude information114 and feedbackbase band signal124. The other actions thereof are the same as those of the third embodiment.
• Thus, according to the fourth embodiment, it is possible to obtain effects similar to those of the third embodiment, and since the amplitude calculating section is omitted from the nonlinear[0075]distortion compensating section201, it is possible to further simplify the apparatus than the third embodiment, and the entire system can be small-sized.
• (Embodiment 5)[0076]
• FIG. 5 is a main block diagram of a transmission apparatus according to a fifth embodiment of the invention. However, parts of the fifth embodiment shown in FIG. 5, which correspond to those of the first embodiment shown in FIG. 1, are given the same reference numbers, and the description thereof is omitted.[0077]
• In FIG. 5,[0078]reference number501 is a nonlinear distortion compensating section,reference number502 is a threshold value storing section,reference number503 is an amplitude comparator,reference number504 is a first compensation table,reference number505 is a second compensation table,reference number506 is a coefficient selecting section,reference number512 is an estimating section,reference number513 is a writing selecting section, reference number516 is threshold value information,reference number517 is a result of amplitude comparison,reference number518 is a first compensation coefficient,reference number519 is a second compensation coefficient,reference number520 is a distortion compensation coefficient,reference number527 is a coefficient renewing signal,reference number528 is a first updating signal,reference number529 is a second updating signal.
• A description is given of the actions of a transmission apparatus thus constructed. The[0079]amplitude calculating section105 calculates and outputs amplitudeinformation117 on the basis oftransmission signal116. The thresholdvalue storing section502 outputs threshold value information516. Thecomparator503 comparesamplitude information117 with threshold value information516, and outputs theresult517 of amplitude comparison, which shows whether the amplitude is grater or smaller than the threshold value.
• The first compensation table[0080]504 and the second compensation table505 output thefirst compensation coefficient518 and thesecond compensation coefficient519 in compliance withamplitude information117.Coefficient selecting section506 selects any one of thefirst compensation coefficient518 and thesecond compensation coefficient519 on the basis of theresult517 of amplitude comparison and outputsdistortion compensation coefficient520.
• For example, in a case where the[0081]result517 of amplitude comparison shows that the amplitude is smaller than the threshold value, thecoefficient selecting section506 selects thefirst compensation coefficient518 and outputs it asdistortion compensation coefficient520. If it is shown that the amplitude is greater than the threshold value, thecoefficient selecting section506 selects thesecond compensation coefficient519 and outputs it asdistortion compensation coefficient520. Thedistortion compensating section107 calculates distortion compensation signal521 on the basis oftransmission signal113 anddistortion compensation coefficient520 and outputs it to thequadrature modulating section108.
• Furthermore, using the transmission signal[0082]514 as the target value, theestimating section512 renews acoefficient updating signal527 in compliance with the distortion compensation coefficient read ascoefficient updating signal527 through thewrite selecting section513, amplitude information515,amplitude comparison result517 and feedbackbase band signal124 and outputs thefirst updating signal528 or thesecond updating signal529.
• The[0083]write section section513 selects the renewedcoefficient updating signal527 from thefirst updating signal528 and thesecond updating signal529 on the basis of theamplitude comparison result517 and renews the distortion compensation coefficients of the first compensation table504 or the second compensation table505. For example, in a case where theamplitude comparison result517 shows that the amplitude is smaller than the threshold value, thewrite selecting section513 selects the renewedcoefficient updating signal527 from thefirst updating signal528 and renews a distortion compensation coefficient of the first compensation table504, and in a case where theamplitude comparison result517 shows that the amplitude is larger than the threshold value, thewrite selecting section513 selects the renewedcoefficient updating signal527 from thesecond updating signal529, and renews the distortion compensation coefficient of the second compensation table505.
• Therefore, in a prior nonlinear distortion compensation technique, the maximum amplitude signal is assigned to the maximum output value of an amplifier. However, since signals having the maximum amplitude have a very low ratio of existence, they will not exert any great influence as leak power even though the maximum amplitude signals are slightly distorted. Therefore, the distortion compensation coefficient is renewed so as to keep the linearity in the first compensation table, and the distortion compensation coefficient is renewed so as to adjust only the phase in the second compensation table, wherein it is possible to cause signals of a large amplitude to have a feature by which the signals are not greatly distorted since the linearity is kept at the phase components while the amplitude is properly limited by a lowering of the gain of the amplifier.[0084]
• Furthermore, since the amplitude of the maximum amplitude signal is limited, the mean amplitude is relatively increased, and it is possible to improve the amplification efficiency of an amplifier.[0085]
• Thus, according to the fifth embodiment, since it is possible to control the distortion components with a simple construction, it is possible to construct a more efficient transmission apparatus than a conventional nonlinear distortion compensation technique.[0086]
• (Embodiment 6)[0087]
• FIG. 6 is a main block diagram of a transmission apparatus according to the sixth embodiment of the invention.[0088]
• In FIG. 6,[0089]reference number600 indicate a nonlinear distortion compensating section,reference number601 indicate a transmission digital quadrature base band signal on I and Q channels,reference number602 indicate a power calculating section,reference number603 indicate an amplitude value calculated in thepower calculating section602,reference number604 indicate a compensation coefficient calculating section for nonlinear distortion compensation,reference number605 indicate quadrature nonlinear distortion compensation data,reference number606 indicate a distortion compensating section,reference number607 indicate a quadrature base band signal for which nonlinear distortion is compensated,reference number608 indicate a D/A converting section,reference number609 indicate an analog quadrature base band signal,reference number610 indicate a low band pass filter for limiting the band,reference number611 indicate a band-limited analog quadrature base band signal,reference number612 indicate a quadrature modulator,reference number613 indicate a modulation signal,reference number614 indicate a transmission system amplifier, andreference number615 indicate an amplified transmission modulation signal.
• Furthermore, the nonlinear[0090]distortion compensating section600 is achievable by a surplus calculation performance of DSP (not illustrated), which is a component of the transmission apparatus. That is, calculation equations which are used by eachpower calculating section602, compensationcoefficient calculating section604, anddistortion compensating section606 is incorporated in programs of the DSP, and a coefficient which the compensationcoefficient calculating section604 uses for calculation is achievable by being stored in a data area in the programs of the DSP.
• A description is given of the actions of the transmission apparatus thus constructed. Firstly, an[0091]amplitude value603 of a transmission signal is calculated by thepower calculating section602 on the basis of the transmission digital quadraturebase band signal601. This is calculated as shown in the following equation (1) where theamplitude value603 is assumed to be “P”.
• P=I²+Q²  (1)
• Next, using the calculated transmission[0092]signal amplitude value603 as an input value, nonlineardistortion compensation data605, having an inversed characteristic of the transmission system nonlinear distortion characteristics, in which the nonlinear distortion compensation data is quadratured, is calculated by the compensationcoefficient calculation section604. This is, for example, an n-dimensional polynomial in which P is used as an input, wherein the same phase component Ci and quadrature component Cq are calculated as in the following equations (2) and (3).
• Ci=a_inPⁿ+a_in-1P^n-1+ . . . +a_i1P¹+a_i0P⁰  (2)
• Cq=a_qnPⁿ+a_qn-1P^n-1+ . . . +a_q1P¹+a_q0P⁰  (3)
• The[0093]distortion compensating section606 provides a complex product of the transmission digital quadraturebase band signal601 and the quadratured nonlineardistortion compensation data605 and outputs a quadraturebase band signal607, the nonlinear distortion of which is compensated. This is calculated as in the following equations (4) and (5) where I and Q channel components of the quadraturebase band signal607 are respectively I′ and Q′;
• I′=IC_i−QC_q  (4)
• Q′=IC_q+QC_i  (5)
• The quadrature[0094]base band signal607 in which the nonlinear distortion is compensated is converted to analog signals by a D/A converting section608, and is band-limited by a lowband pass filter610, wherein an analog quadraturebase band signal611 is obtained. After quadrature modulation is carried out by aquadrature modulator612 and a modulatedsignal613 is obtained, it is amplified to a necessary size by atransmission system amplifier614, wherein atransmission modulation signal615 is outputted.
• Furthermore, a[0095]quadrature modulator612 is replaced for such a type as is able to carry out quadrature modulation of digital quadrature base band signals, and a D/A converter and a low band pass filter may be connected between the quadrature modulator andamplifier614.
• This, according to the sixth embodiment, the nonlinear[0096]distortion compensating section600 is constructed so that signal power is obtained from the inputted quadrature base band signal, a distortion compensation coefficient is calculated by an approximation equation for distortion compensation, in which the value is used as a parameter, nonlinear distortion compensation is carried out using the distortion compensation coefficient, and simultaneously the coefficient of the approximation equation is renewed using an error between the quadrature signal obtained by demodulating the output to which the modulation output is shared, and the quadrature base band signal. Therefore, nonlineardistortion compensating section600 for compensating nonlinear distortions generated in thetransmission system amplifier614 can be constructed to be small-sized without use of memory tables achieved by a RAM or a ROM, etc.
• (Embodiment 7)[0097]
• FIG. 7 is a main block diagram of a transmission apparatus of a seventh embodiment of the invention. However, parts of the seventh embodiment, shown in FIG. 7, which correspond to those of the sixth embodiment shown in FIG. 6 are given the same reference numbers, and the description thereof is omitted.[0098]
• In FIG. 7,[0099]reference number700 indicate a nonlinear distortion compensating section,reference number704 indicate a compensation coefficient calculating section for amplitude distortion compensation,reference number705 indicate amplitude distortion compensation data,reference number707 indicate an analog quadrature base band signal,reference number709 indicate a band-limited analog quadrature base band signal,reference number711 indicate a modulation signal,reference number712 indicate a gain controlling amplifier for amplitude distortion compensation, andreference number613 indicate a modulation signal, the amplitude distortion of which is compensated. Furthermore, the nonlineardistortion compensating section700 is achievable by surplus calculation performance of the DSP (not illustrated), which is a component of the transmission apparatus.
• A description is given of the actions of the transmission apparatus thus constructed. First,[0100]amplitude value603 of transmission signal is calculated by thepower calculating section602 on the basis of transmission digital quadraturebase band signal601. Next, theamplitude value603 of the calculated transmission signal is used as an input value, wherein amplitudedistortion compensation data705 having an inversed characteristic of the amplitude distortion characteristic of the transmission system is calculated by the compensationcoefficient calculating section704 using an approximation equation.
• On the other hand, transmission digital quadrature[0101]base band signal601 is converted to analog signals by D/A conversion section608, and the band is limited by a lowband pass filter610, wherein an analog quadraturebase band signal709 is obtained. After quadrature modulation is carried out by aquadrature modulator612 to obtain amodulation signal711, amplitude distortion compensation is carried out by again controlling amplifier712 for compensating the amplitude distortion on the basis of amplitudedistortion compensation data705, thereby causing amodulation signal613 to be obtained, the amplitude distortion of which is compensated. Finally, the signal is amplified to a size necessary for theamplifier614, and atransmission modulation signal615 is outputted.
• Furthermore, it may be constructed that the[0102]quadrature modulator612 is replaced for such a type that modulates the digital quadrature base band signals for quadrature, and a D/A converting section and a low band pass filter are connected between the quadrature modulator and gain controllingamplifier712.
• Thus, according to the seventh embodiment, since the nonlinear[0103]distortion compensating section700 is constructed so that signal power is obtained from the quadrature base band signal inputted, the amplitude distortion compensation coefficient is calculated by an approximation equation for compensating the distortion, in which the value is used as a parameter, the amplitude distortion of the quadrature modulation signal is compensated on the basis of the amplitude distortion compensating coefficient using the same coefficient, and a modulation signal is obtained, the amplitude distortion of which is compensated. Thus, the nonlineardistortion compensating section700 can be constructed to be small-sized without use of a memory table which is achieved by a RAM or ROM, etc.
• (Embodiment 8)[0104]
• FIG. 8 is a main block diagram of a transmission apparatus according to an eighth embodiment of the invention. However, parts of the eighth embodiment, shown in FIG. 8, which correspond to those of the sixth and seventh embodiments shown in FIG. 6 and FIG. 7 are given the same reference numbers, and the description thereof is omitted.[0105]
• In FIG. 8,[0106]reference number800 indicate a nonlinear distortion compensating section,reference number816 indicate a directivity coupler,reference number817 indicate a transmission modulation signal shared,reference number818 indicate a quadrature demodulator,reference number819 indicate a quadrature base band signal, the quadrature of which is detected,reference number820 indicate a low band pass filter for limiting the band,reference number821 indicate a quadrature base band signal, the band of which is limited,reference number822 indicate an A/D converter section,reference number823 indicate digital quadrature base band signal,reference number824 indicate a coefficient renewing section.Reference number825 indicate coefficient data of an approximation equation for calculation of a compensation coefficient.
• Furthermore, the[0107]power calculating section602, compensationcoefficient calculating section704 andcoefficient renewing section824 of the nonlineardistortion compensating section800 are achievable through the surplus calculation performance of the DSP (not illustrated), which is a component of the transmission apparatus.
• A description is given of the actions of the transmission apparatus thus constructed. Firstly, the[0108]amplitude value603 of transmission signal is calculated by thepower calculating section602 on the basis of transmission digital quadraturebase band signal601. Next, thecalculated amplitude value603 of the transmission signal is used as an input value, wherein amplitudedistortion compensation data705 having an inversed characteristic of the amplitude distortion characteristics of transmission system is calculated by the compensationcoefficient calculating section704 using an approximation equation.
• On the other hand, the transmission digital quadrature[0109]base band signal601 is converted to analog signals by the D/A converting section606, and the band is limited by a lowband pass filter610, thereby causing an analog quadraturebase band signal709 to be obtained. After quadrature modulation is carried out byquadrature modulator612 to obtainmodulation signals711, the amplitude distortion compensation is carried out by again controlling amplifier712 for compensating the amplitude distortion on the basis of the amplitudedistortion compensation data705, thereby causing modulation signals713 to be obtained, the amplitude distortion of which is compensated. The signals are amplified to a necessary size by anamplifier614, and transmission modulation signals615 are outputted. At this time, the transmission modulation signals615 are shared by adirectivity coupler816.
• The shared transmission modulation signals[0110]817 are detected by aquadrature demodulator818. After they pass through a lowband pass filter820 for limiting the band, they are converted to digital signals by an A/D converting section822, thereby causing digital quadrature base band signals823 to be obtained. Thecoefficient data825 of the approximation equation is renewed by thecoefficient renewing section824 so that the difference between the amplitude of digital quadraturebase band signal823 and theamplitude value603 of the transmission signal is minimized.
• Thus, according to the eighth embodiment, the nonlinear[0111]distortion compensating section800 is constructed so that signal power is obtained on the basis of the inputted quadrature base band signals, the amplitude distortion compensation coefficient is calculated by an approximation equation for compensating the distortion, in which the value of signal power is used as a parameter, an amplitude distortion of the quadrature modulation signal is compensated on the basis of the amplitude distortion compensation coefficient using the coefficient, the modulation signals, the amplitude distortion of which is compensated, is shared, and the amplitude compensation coefficient is renewed so that the difference between the detected signal (output signal) and the input signal having power obtained beforehand is minimized after the shared modulation signals are detected for quadrature. Therefore, the nonlineardistortion compensating section800 can be constructed to be small-sized without use of a memory table achievable by a RAM or ROM, etc., and at the same time it is possible to compensate distortion changes due to environmental changes such as in temperature, etc.
• (Embodiment 9)[0112]
• FIG. 9 is a main block diagram of the transmission apparatus of a ninth embodiment of the invention. However, parts of the ninth embodiment shown in FIG. 9, which correspond to those of the sixth and eighth embodiments shown FIG. 6 and FIG. 8 are given the same reference numbers, and the description thereof is omitted.[0113]
• In FIG. 9,[0114]reference number900 indicate a nonlinear distortion compensating section,reference number904 indicate a fixed coefficient reference section by ROM, which refers to a fixed compensation coefficient for compensating nonlinear distortions using theamplitude value603,reference number905 indicate a quadratured fixed nonlinear distortion compensation coefficient,reference number908 indicate a distortion compensating section,reference number926 indicate a coefficient renewing section, andreference number927 indicate coefficient data of an approximation equation for calculation of compensation coefficients.
• Furthermore, the[0115]power calculating section602, compensationcoefficient calculating section604 andcoefficient renewing section926 of the nonlineardistortion compensating section900 are achievable by surplus calculation performance of the DSP (not illustrated), which is a component of the transmission section.
• A description is given of the actions of a transmission section thus constructed. First, the[0116]amplitude value603 of transmission signals is calculated by thepower calculating section602 on the basis of the transmission digital quadraturebase band signal601 as in the abovementioned equation (1). Next, with reference to the fixedcoefficient reference section904 as using theamplitude value603 of the calculated transmission signal as an address, the nonlinear distortion compensation data having an inversed characteristic of the nonlinear distortion characteristics of the transmission system calculated in advance is obtained as a quadratured nonlineardistortion compensation coefficient905.
• Herein, it is assumed that wherein the[0117]amplitude value603 is P as shown in the equation (1), a nonlineardistortion compensation coefficient905 corresponding to P is (di, dq).
• Simultaneously, the[0118]amplitude value603 of the transmission signal calculated is used as an input value, wherein a correctingcoefficient605 for correcting the nonlineardistortion compensation coefficient905 is calculated by the correctingcoefficient calculating section604 using the abovementioned approximation equations (2) and (3).
• The[0119]distortion compensating section908 carries out a complex product of a transmission digital quadraturebase band signal601, a quadratured nonlineardistortion compensation data905 and correctingcoefficient605, and outputs a quadraturebase band signal607, the nonlinear distortion of which is compensated.
• This is calculated by the following equations (6) and (7), first using (di, dq) of the nonlinear distortion compensation coefficient where the I and Q channel components of the quadrature[0120]base band signal607 are respectively I″ and Q″.
• I′=Idi−Qdq  (6)
• Q′=Idq+Qdi  (7)
• Next, (Ci, Cq) of the correcting[0121]coefficient605 is used with respect to the result of the abovementioned equations (6) and (7), and calculation is made as in the following equations (8) and (9).
• I″=I′Ci−Q′Cq  (8)
• Q″=I′Cq+Q′Ci  (9)
• The quadrature base band signals[0122]607 for which the nonlinear distortion is thus compensated are converted to analog signals by a D/A conversion section608 and the band thereof is limited by a lowband pass filter610, thereby causing analog quadrature base band signals611 to be obtained. After the signals are, quadrature-modulated by aquadrature modulator612 to obtainmodulation signals613, they are amplified by anamplifier614 of the transmission system to a necessary size, and transmission modulation signals615 are outputted. At this time, the transmission modulation signals615 are shared by adirectivity coupler816.
• The shared transmission modulation signals[0123]817 are detected by aquadrature demodulator818, and pass through a lowband pass filter820 for limiting the band. Thereafter, the signals are converted to digital signals by an A/D converting section822 to obtain digital quadrature base band signals823. Thecoefficient data927 of approximation equations for calculating the correcting coefficients are renewed by acoefficient renewing section926 so that the difference between the quadrature base band signals601 and823 is minimized.
• Thus, according to the ninth embodiment, the nonlinear[0124]distortion compensating section900 is constructed so that signal power is obtained from the quadrature base band signals inputted, nonlinear distortion compensation coefficients are obtained using the value of signal power as a parameter, compensation coefficients are calculated by approximation equations for compensating distortions to carry out distortion compensations using the coefficients, modulation signals in which the distortion compensation signals are modulated for quadrature are shared, and the compensation coefficients of approximation equations are renewed so that the difference between the detection signals (output signals) and input signals for which power is obtained in advance is minimized after the shared modulation signals are detected for quadrature. Therefore, the nonlineardistortion compensating section900 can be constructed so as to achieve high accuracy and compensate the distortions changing in line with changes of the environments due to temperature changes, etc.
• Furthermore, the respective nonlinear[0125]distortion compensating sections600,700,800, and900 described above according to embodiments6 through9 shown in FIG. 6 through9 may be replaced for any one of the nonlineardistortion compensating sections104,201,501 shown in FIG. 1 through5. However, when replacing nonlinear distortion compensation sections, it is necessary that a matching is secured with respect to the type of quadrature modulators, positions of the D/A converting section and low band pass filter, and position ofgain controlling amplifier712 on the basis of the description made with respect to the first through the ninth embodiments.
• Furthermore, each of the nonlinear[0126]distortion compensating sections600,900 may be composed of integrated circuits by a hardware configuration using logic circuits, etc. individually, or with its transmission apparatus included in a DSP (not illustrated), which is a component.
• Still furthermore, three elements, that is,[0127]amplitude calculating section101, limitingcoefficient calculating section301 andamplitude limiting section103 shown in FIG. 3 and FIG. 4 may be composed of integrated circuits by a hardware configuration combination with any one of the respective nonlineardistortion compensating sections600,900, or they maybe composed of integrated circuits by a hardware configuration combined with any one of the respective nonlineardistortion compensating sections600,900, and included in the DSP.
• In a case where they are composed of integrated circuits, the nonlinear distortion compensation can be carried out at a high speed.[0128]
• Industrial Applicability[0129]
• As described above, a transmission apparatus according to the invention is very useful as a transmission apparatus of radio communication systems and is suitable for compensation of nonlinear distortions generated in the transmission system.[0130]

Claims (28)

1. A transmission apparatus comprising:

a first amplitude calculating means for calculating a first amplitude value of a transmission quadrature base band signals;

an amplitude limiting table for storing amplitude limiting information corresponding to said first amplitude value;

a first amplitude limiting means for limiting the amplitude of said transmission quadrature base band signals using said amplitude limiting information;

a quadrature modulating means for modulating the amplitude limited transmission quadrature base band signals to output a radio frequency (RF) signals; and

amplifying means for amplifying said RF signals.

2. The transmission apparatus as set forth inclaim 1, further comprising:

nonlinear distortion compensating means for compensating nonlinear distortion of the transmission quadrature base band signals amplitude limited by the first amplitude limiting means,

wherein the transmission quadrature base band signals for which the nonlinear distortion is compensated by said nonlinear distortion compensating means are inputted into said quadrature modulating means.

3. A transmission apparatus as set forth inclaim 2, wherein

said nonlinear distortion compensating means includes a second amplitude calculating means for calculating a second amplitude value of the transmission quadrature base band signal, the amplitude of which is limited by the first amplitude limiting means; a compensation table for storing nonlinear distortion compensation information corresponding to said second amplitude value; a distortion compensating means for compensating a distortion of the amplitude limited transmission quadrature base band signals by using said nonlinear distortion compensation information to output the transmission quadrature base band signals; coupling means for feeding back a part of radio frequency (RF) signals amplified by an amplifying means; a demodulating means for demodulating said feedback RF signals to feedback base band signals; and an estimating means for updating said nonlinear distortion compensation information using said amplitude-limited transmission quadrature base band signals, said feedback base band signals, and said second amplitude value to rewrite said compensation table.

4. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means includes a compensation table for storing nonlinear compensation information corresponding to the first amplitude value; distortion compensating means for compensating a distortion of the transmission quadrature base band signals, the amplitude of which is limited by the first amplitude limiting means, by using said nonlinear compensation information to output the transmission quadrature base band signals; coupling means for feeding back a part of said RF signals amplified by an amplifying means; demodulating means for demodulating said feedback RF signals to feedback base band signals; and estimating means for updating said nonlinear distortion compensation information by using said amplitude-limited transmission quadrature base band signals, said feedback base band signals and said first amplitude value to rewrite said compensation table.

5. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means includes a second amplitude calculating means for calculating the second amplitude value of the transmission quadrature base band signals having amplitude limited by the first amplitude limiting means; threshold value storing means for storing a threshold value defined in advance; comparing means for comparing said amplitude value with said threshold value; a first compensation table for storing a nonlinear compensation coefficient corresponding to said amplitude value; a second compensation table for storing a phase compensation coefficient corresponding to said amplitude value; coefficient selecting means for selecting said nonlinear compensation coefficient or said phase compensation coefficient on the basis of comparison results of said comparing means; distortion compensating means for compensating the distortion of said transmission quadrature base band signals using said nonlinear compensation coefficient or said phase compensation coefficient, which is selected by said coefficient selecting means; coupling means for feeding back a part of said RF signals amplified by the amplifying means; demodulating means for demodulating said feedback RF signals to feedback base band signals; estimating means for estimating new coefficient information of the respective said nonlinear compensation coefficient and said phase compensation coefficient using said transmission quadrature base band signal, said feedback base band signal, said amplitude value and said comparison result; and writing means for rewriting said nonlinear compensation coefficient and said phase compensation coefficient using said comparison result and said coefficient renewal information.

6. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of transmission quadrature base band signals having amplitude limited by the first amplitude limiting means; compensation coefficient calculating means for calculating a nonlinear distortion compensation coefficient by an approximation equation defined in advance using said power value; and distortion compensating means for compensating the nonlinear distortion of said transmission quadrature base band signals using said nonlinear distortion compensation coefficient.

7. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of transmission quadrature base band signals, the amplitude of which is limited by the first amplitude limiting means; compensating coefficient calculating means for calculating an amplitude distortion compensating coefficient by approximation equations set in advance using said power value; and amplitude distortion compensating means for compensating amplitude distortion using said amplitude compensating coefficient with respect to the quadrature modulation signals obtained by a quadrature modulating means quadrature-modulating said transmission quadrature base band signals.

8. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of transmission quadrature base band signals, the amplitude of which is limited by the first amplitude limiting means; compensating coefficient calculating means for calculating an amplitude distortion compensating coefficient by approximation equations set in advance using said power value; amplitude distortion compensating means for compensating amplitude distortion using said amplitude distortion compensating coefficient with respect to the quadrature modulation signals obtained by said quadrature modulating means quadrature-modulating said transmission quadrature base band signals; coupling means for coupling the outputs of said amplifying means; quadrature demodulating means for quadrature demodulating one of the outputs from said coupling means as an input; and coefficient updating means for calculating a error between the quadrature demodulating signal and said power value through comparison and for updating the value of coefficients of said approximation equations on the basis of said error.

9. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of transmission quadrature base band signals, the amplitude of which is limited by the first amplitude limiting means; table referencing means for outputting a distortion compensation coefficient from a nonlinear distortion compensating table set in advance using said power value; correcting coefficient calculating means for using said power value as an input and for calculating a correcting value of said distortion compensating coefficient using approximation equations; distortion compensating means for compensating nonlinear distortion of said transmission quadrature base band signal using said distortion compensating coefficient and said correcting coefficient; coupling means for coupling the outputs of said amplifying means; quadrature demodulating means for quadrature demodulating one of the outputs of said coupling means as an input; and coefficient updating means for calculating the error between the quadrature demodulating signal and said transmission quadrature base band signal through comparison and for updating the value of coefficients of said approximation equations on the basis of said error.

10. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means is composed of integrated circuits.

11. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means is composed of integrated circuits along with said first amplitude calculating means, said amplitude limiting table, and said first amplitude limiting means.

12. A transmission apparatus as set forth inclaim 2, wherein said nonlinear distortion compensating means is included in a DSP for carrying out transmission processes and is composed of integrated circuits.

13. A transmission apparatus comprising:

a first amplitude calculating means for calculating the first amplitude value from transmission quadrature base band signals;

limiting coefficient calculating means for calculating an amplitude limiting coefficient with respect to said first amplitude value;

a second amplitude limiting means for limiting the amplitude of said transmission quadrature base band signals using said amplitude limiting coefficients;

quadrature modulating means for quadrature modulating the amplitude-limited transmission quadrature base band signals to output RF signals; and

amplifying means for amplifying said RF signals.

14. A transmission apparatus as set forth inclaim 13, further comprising nonlinear distortion compensating means for compensating nonlinear distortion of the transmission quadrature base band signals, the amplitude of which is limited by the second amplitude limiting means, wherein the transmission quadrature base band signals in which the nonlinear distortion is compensated by said nonlinear distortion compensating means are inputted into said quadrature modulating means.

15. A transmission apparatus as set forth inclaim 14, wherein said nonlinear distortion compensating means includes a second amplitude calculating means for calculating the second amplitude value of the transmission quadrature base band signals, the amplitude of which is limited by the second amplitude limiting means; a compensating table for storing nonlinear compensation information with respect to said second amplitude value; distortion compensating means for compensating distortion of the amplitude-limited transmission quadrature base band signals using said nonlinear compensation information to output the amplitude-limited transmission quadrature base band signals; coupling means for feeding back a part of RF signals amplified by an amplifying means; demodulating means for demodulating said fed back RF signals to feed back base band signals; and estimating means for updating said nonlinear compensation information using said amplitude-limited transmission quadrature base band signals, said feedback base band signals and said second amplitude value and rewriting said compensation table.

16. A transmission apparatus as set forth inclaim 14, wherein said nonlinear distortion compensating means includes a compensation table for storing nonlinear compensation information corresponding to the first amplitude value; distortion compensating means for compensating nonlinear distortion of the amplitude limited transmission quadrature base band signals using said nonlinear compensation information to output the distortion compensated transmission quadrature base band; coupling means for feeding back a part of said RF signals amplified by said amplifying means; demodulating means for demodulating said fed back RF signals to feedback base band signals; estimating means for updating said nonlinear compensation information using said amplitude-limited transmission quadrature base band signals, said feedback base band signals and said first amplitude value and for rewriting said compensation table.

17. A transmission apparatus as set forth inclaim 14, wherein said nonlinear distortion compensating means includes a second amplitude calculating means for calculating the second amplitude value of the transmission quadrature base band signals, the amplitude of which is limited by the second amplitude limiting means; threshold value storing means for storing threshold values defined in advance; comparing means for comparing said amplitude values with said threshold values; a first compensation table for storing a nonlinear compensation coefficient corresponding to said amplitude value; a second compensation table for storing a phase compensation coefficient corresponding to said amplitude value; coefficient selecting means for selecting said nonlinear compensation coefficient or said phase compensation coefficient on the basis of the results of comparison of said comparing means; distortion compensating means for compensating distortion of said transmission quadrature base band signals using said nonlinear compensation coefficient or said phase compensation coefficient selected by said coefficient selecting means; coupling means for feeding back a part of said RF signals amplified by the amplifying means; demodulating means for demodulating said fed back RF signals to feedback base band signals; estimating means for estimating new coefficient information of each of said nonlinear compensation coefficient and said phase compensation coefficient using said transmission quadrature base band signals, said feedback base band signals, said amplitude values and said comparison results; and rewriting means for rewriting said nonlinear compensating coefficient and said phase compensating coefficient using said comparison results and said new coefficient information.

18. A transmission apparatus as set forth inclaim 14, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of the transmission quadrature base band signals, the amplitude of which is limited by the second amplitude limiting means; compensating coefficient calculating means for calculating nonlinear distortion compensating coefficient by approximation equations set in advance using said power value; and distortion compensating means for compensating nonlinear distortion of said transmission quadrature base band signals using said nonlinear distortion compensating coefficient.

19. A transmission apparatus as set forth inclaim 14, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of the transmission quadrature base band signals, the amplitude of which is limited by the second amplitude limiting means; compensating coefficient calculating means for calculating amplitude distortion compensating coefficient by approximation equations set in advance using said power value; and amplitude distortion compensating means for compensating amplitude distortion using said amplitude distortion compensating coefficient with respect to the quadrature modulating signals obtained by said transmission quadrature base band signals being quadrature-modulated by said quadrature modulating means.

20. A transmission apparatus as set forth inclaim 14, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of the transmission quadrature base band signals, the amplitude of which is limited by the second amplitude limiting means; compensating coefficient calculating means for calculating amplitude distortion compensating coefficient by approximation equations set in advance using said power value; and amplitude distortion compensating means for compensating amplitude distortion using said amplitude distortion compensating coefficient with respect to the quadrature modulating signals obtained by said transmission quadrature base band signals being quadrature-modulated by said quadrature modulating means; coupling means for coupling the outputs of the amplifying means; quadrature demodulating means for using one of the outputs of said coupling means as an input and for detecting the same for quadrature; and coefficient updating means for calculating the error by comparing the quadrature demodulating signal with said power value and for updating the coefficient value of said approximation equations on the basis of said errors.

21. A transmission apparatus as set forth inclaim 14, wherein said nonlinear distortion compensating means includes power calculating means for calculating a power value of the transmission quadrature base band signals, the amplitude of which is limited by the second amplitude limiting means; table referencing means for taking out distortion compensation coefficients from a nonlinear distortion compensation table set in advance using said power value; correcting coefficient calculating means for using said power value as an input and for calculating a correcting value of said distortion compensation coefficient using approximation equations; distortion compensating means for compensating nonlinear distortion compensation of said transmission quadrature base band signals using said distortion compensating coefficients and said correcting coefficients; coupling means for coupling the outputs of the amplifying means; quadrature demodulating means for using one of the outputs of said coupling means as an input and for detecting the same for quadrature; and coefficient updating means for calculating an error between the quadrature demodulating signal and said transmission quadrature base band signal and for updating the coefficient of said approximation equations on the basis of said error.

22. A transmission apparatus as set forth inclaim 14, wherein the nonlinear distortion compensating means is composed of integrated circuits.

23. A transmission apparatus as set forth inclaim 14, wherein the nonlinear distortion compensating means is composed of integrated circuits together with the first amplitude calculating means, amplitude limiting table and first amplitude limiting means.

24. A transmission apparatus as set forth inclaim 14, wherein the nonlinear distortion compensating means is included in a DSP for carrying out transmission processes and is composed of integrated circuits.

25. A transmission apparatus comprising:

power calculating means for calculating a power value of transmission quadrature base band signals;

compensating coefficient calculating means for calculating a nonlinear distortion compensating coefficient by approximation equations set in advance using said power value;

distortion compensating means for compensating nonlinear distortion of said transmission quadrature base band signals using said nonlinear distortion compensating coefficients;

quadrature modulating means for quadrature-modulating the distortion-compensated transmission quadrature base band signals; and

amplifying means for amplifying said quadrature modulating signals.

26. A transmission apparatus comprising:

power calculating means for calculating a power value of a transmission quadrature base band signal;

compensation coefficient calculating means for calculating an amplitude distortion compensating coefficient by approximation equations set in advance using said power value;

quadrature modulating means for quadrature-modulating said transmission quadrature base band signals;

amplitude distortion compensating means for compensating amplitude distortion of the quadrature modulation signals using said amplitude distortion compensating coefficients.

27. A transmission apparatus comprising:

power calculating means for calculating a power value of a transmission quadrature base band signal;

compensation coefficient calculating means for calculating an amplitude distortion compensating coefficient by approximation equations set in advance using said power value;

quadrature modulating means for quadrature-modulating said transmission quadrature base band signals;

amplitude distortion compensating means for compensating amplitude distortion of quadrature modulation signals using said amplitude distortion compensating coefficients;

amplifying means for amplifying modulation signals;

coupling means for coupling the outputs of said amplifying means;

quadrature demodulating means for using one of the outputs of said coupling means as an input and for quadrature demodulating the same; and

coefficient renewing means for calculating an error by comparing the quadrature demodulating signal with said power value and for renewing the value of coefficient of said approximation equations on the basis of said error.

28. A transmission apparatus comprising:

power calculating means for calculating a power value of a transmission quadrature base band signal;

table referencing means for outputting distortion compensating coefficients from a nonlinear distortion compensating table set in advance using said power value;

correcting coefficient calculating means for using said power value as an input and for calculating a correcting value of said distortion compensating coefficient using approximation equations;

distortion compensating means for compensating nonlinear distortion of said transmission quadrature base band signals using said distortion compensation coefficient and said correcting coefficient;

quadrature modulating means for quadrature-modulating the outputs of said distortion compensating means;

amplifying means for amplifying the outputs of said quadrature modulating means;

coupling means for coupling the outputs of said amplifying means;

quadrature demodulating means for using one of the outputs of said coupling means as an input and for quadrature demodulating the same; and

coefficient updating means for calculating an error by comparing said quadrature demodulating signal and said transmission quadrature base band signal and for renewing the coefficients of said approximation equations on the basis of said error.

Images