CA2153617A1 - Cdma receiving apparatus - Google Patents
Cdma receiving apparatusInfo
- Publication number
- CA2153617A1 CA2153617A1 CA002153617A CA2153617A CA2153617A1 CA 2153617 A1 CA2153617 A1 CA 2153617A1 CA 002153617 A CA002153617 A CA 002153617A CA 2153617 A CA2153617 A CA 2153617A CA 2153617 A1 CA2153617 A1 CA 2153617A1
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- Prior art keywords
- pilot channel
- signal
- interference signal
- receiving apparatus
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J13/00—Code division multiplex systems
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- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
- Noise Elimination (AREA)
Abstract
In a CDMA receiving apparatus, the receiving performance is improved by providing a circuit for providing a signal after despreading with weights and by controlling the weights adaptively so as to minimize the interference signal component contained in the correlatively detected signal. A received signal subjected to quasi-synchronous detection in a quasi-synchronous detector circuit is despread by a data channel despreading circuit. The despread signal is provided with weights in a data channel weight multiplication circuit and integrated in a data channel signal integration circuit. An interference signal component contained in the signal after integration is extracted by an interference signal component extraction circuit. The weights in the data channel weight multiplication circuit are controlled by a weight control circuit on the basis of the interference signal component so as to minimize the interference component.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a receiving apparatus of a communication system using a CDMA
scheme.
In recent years, demands for land mobile communication such as automobile telephone and portable telephone have significantly increased. Efficient frequency utilization techniques for assuring a larger customer capacity on a limited frequency band are increasingly important. As one of multiple access schemes for efficient frequency use, the code division multiple access (CDMA) scheme is attracting attention.
The CDMA scheme is a multiple access scheme using a spread spectrum communication technique and it is not susceptible to influence of multipath distortion. In the CDMA scheme, a diversity effect can also be anticipated because of a RAKE receiver which combines multipath components with maximal ratio combining. A
land mobile communication system using the CDMA scheme is described in U.S. Patent No. 4,901,307, for example.
In U.S. Patent No. 4,901,307, a CDMA
communication technique in the case where a plurality of users communicate via a base station is disclosed.
Such a scheme that all base stations transmit pilot ~ - 2 _ 21~ 3617 signals having the same frequency and spread codes in a CDMA system is well known. In the above described U.S.
Patent, a pilot signal is used to procure initial synchronization in a mobile device. In addition, pilot signals are used as reference of carrier phase offset and carrier frequency offset and a reference time of a frame transmitted from a base station as well.
Hereafter, the configuration of a conventional receiving apparatus for the scheme in which the pilot signals are transmitted as explained in the U.S. Patent No. 4,901, 307 will be described.
FIG. 1 is a block diagram showing the configuration of the above described conventional receiving apparatus. In FIG. 1, numeral 1 denotes a quasi-synchronous detector circuit for performing quasi-synchronous detection on a received radio frequency signal. Numeral 2 denotes a data channel despreading circuit for performing despreading by using spreading codes assigned to a data channel. Numeral 4 denotes a data channel signal integration circuit for integrating a despread data channel signal. Numeral 5 denotes a pilot channel despreading circuit for performing despreading by using spreading codes assigned to a pilot channel. Numeral 6 denotes a pilot channel signal integration circuit for integrating a despread pilot channel signal. Numeral 7 denotes a carrier phase offset correction circuit for correcting _ _ 3 _ 2153617 a carrier phase offset contained in a data channel signal. Numeral 10 denotes a received signal. Numeral 11 denotes demodulated data.
Operation of the above described conventional circuit will now be described by referring to FIG. 1.
The received signal 10 is subjected to quasi-synchronous detection in the quasi-synchronous detector circuit 1 to produce a baseband signal. This baseband signal is despread in the data channel despreading circuit 2. At this time, the despreading is performed by using a spreading sequence assigned to a data channel. The despread signal is integrated in the data channel signal integration circuit 4. By the despreading operation and integration operation, the signal of assigned data channel can be extracted. The integrated signal contains the difference between the carrier phase of the received signal 10 and the carrier phase of a local oscillator.
On the other hand, the baseband signal outputted from the quasi-synchronous detector circuit 1 is despread in the pilot channel despreading circuit 5.
At this time, the despreading is performed by using a spreading sequence assigned to a pilot channel. The despread signal is integrated in the pilot channel signal integration circuit 6. Since a signal known on the receiving side is inserted in the pilot channel, the difference between the carrier phase of the . - 4 -received signal 10 and the carrier phase of the local oscillator can be known.
In the carrier phase offset correction circuit, demodulated data 11 having a corrected carrier phase offset can be obtained by using the result of integration of the data channel signal and the result of integration of the pilot channel signal thus obtained.
In the above described conventional receiving apparatus, however, correlation levels with respect to other channel components become great because of an increased number of multiple users and multipath distortion, resulting in great interference components contained in the correlatively detected data channel signal and pilot channel signal. As a result, errors are caused in demodulated data and the communication quality is degraded. Also in the case where a narrow band interference signal is contained in the receceived signal, interference components contained in the correlatively detected data channel signal and pilot channel signal become great, resulting in degradation in communication quality.
SUMMARY OF THE INVENTION
The present invention solves the above described problems of the conventional technique. An object of the present invention is to provide a CDMA
` 2153617 _ - 5 -receiving apparatus capable of reducing errors of demodulated data and improving the receiving quality.
In accordance with the present invention, the receiving apparatus includes means for providing the signals after despreading with weights and the weights are adaptively controlled so as to m;n;m; ze the interference signal component contained in the correlatively detected signal. Thereby, the interference signal component can be reduced and the above described object is achieved.
Owing to this configuration, errors in the demodulated data are reduced and the communication quality can be improved. Furthermore, it is also possible to increase the number of users which can use the communication while maintaining the communication quality at substantially the same level. Efficient use of frequency resources can thus be realized.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram of a conventional CDMA receiving apparatus;
FIG. 2 is a block diagram of a first embodiment of a CDMA receiving apparatus according to the present invention;
FIG. 3 is a diagram showing a transmitted signal of a CDMA transmitting apparatus;
FIG. 4 is a diagram showing a received signal of a CDMA receiving apparatus;
_ - 6 - 2153617 FIG. 5 iS a block diagram of an interference signal component extracting circuit of a CDMA receiving apparatus according to the present invention;
FIG. 6 is a block diagram showing a first configuration example of a weight control circuit of a CDMA receiving apparatus according to the present nventlon;
FIG. 7 iS a block diagram showing a second configuration example of the weight control circuit of the CDMA receiving apparatus according to the present invention;
FIG. 8 iS a diagram showing demodulated data of a CDMA receiving apparatuse according to the present invention and a convention CDMA receiving apparatus;
FIG. 9 iS a block diagram of a second embodiment of a CDMA receiving apparatus according to the present invention;
FIG. 10 iS a block diagram of an interference signal component extracting circuit used in the second embodiment and a third embodiment of a CDMA receiving apparatus according to the present invention; and FIG. 11 iS a block diagram of the embodiment of a CDMA receiving apparatus according to the present lnvent lon .
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 2 is a block diagram showing the configuration of a first embodiment according to the _ 7 _ 21S3B17 -present invention. Numericals 1, 2, 4, 5, 6, 7, 10 and 11 shown in FIG. 2 denote the same components as those of FIG. 1 denoted by like numerals and duplicated description of them will be omitted. In FIG. 2, numeral 3 denotes a data channel weight multiplication circuit for providing despread data channel signals with weights. Numeral 8 denotes an interference signal component extraction circuit for extracting the interference signal component of the data channel from the correlatively detected signal component. Numeral 9 denotes a weight control circuit for controlling weights in the data channel weight multiplication circuit 3 on the basis of the extracted interference signal component of the data channel.
Operation of the CDMA receiving apparatus configured as heretofore described will now be described. If a signal as shown in FIG. 3 is transmitted by a base station, the received signal 10 shown in FIG. 4 is received by the receiving apparatus.
The received signal 10 is subjected to quasi-synchronous detection in the quasi-synchronous detector circuit 1 to produce a baseband signal. This baseband signal is despread in the data channel despreading circuit 2. In the signal despread in the data channel despreading circuit 2, signal components of spreading channels used by other users and interference signal components such as signal components of a delayed wave . 2153617 _ - 8 -or a lead wave caused by multipath propagation are also contained besides the signal component of the assigned spreading channel. Weights in the data channel weight multiplication circuit 3 are determined so that the above described interference signal component may be reduced to the minimum by the integrating operation in the data channel signal integration circuit 4. In the output signal of the data channel signal integration circuit 4, the correlatively detected data channel signal component and the correlatively detected interference signal component are contained. In the interference signal component extraction circuit 8, the correlatively detected interference signal component is extracted. In the extracted signal, information of spreading codes which are being used by other users and information of multipath propagation path state are contained.
A configuration example of the interferene signal component extraction circuit is shown in FIG. 5.
In FIG. 5, numeral 15 denotes a data judgement circuit for judging an output signal of the data channel signal integration circuit 4. Numeral 16 denotes an output signal of the data channel signal integration circuit 4. Numeral 17 denotes a signal obtained after judgement in the data judgement circuit 15. Numeral 18 denotes an extracted interference signal component.
In the signal 16, a signal component x(t) of the assigned channel and an interference component e(t) ` 2153617 g caused by other channels or multipath are contained.
Therefore, the signal 16 can be represented by the following equation.
y(t) = x(t) + e(t) (1) The data judgement circuit 15 forms a hard decision upon the soft decision value signal 16 and derives a discrete signal value of the assigned channel. If this judgement is performed correctly, the signal 17 becomes equal to x(t). Therefore, the interference signal component can be derived as represented by the following equation.
Signal 16 - Signal 17 = y(t) - x(t) = e(t) (2) In the output signal of the data channel signal integration circuit 4, the carrier phase offset is contained. When the above described judgement is to be formed, the carrier phase offset information fed from the pilot channel signal integration circuit 6 is needed.
By using the interference signal component thus derived, the weight control circuit 9 derives optimum weight values for the data channel weight multiplication circuit 3.
-- - 10 _ 21~3617 The case where minim; zation of the mean square value of the interference signal component is used as criterion for deriving the optimum value will now be described. In the output signal of the data channel despreading circuit 2, the signal of chip rate corresponding to data at time nT (where T is the transmission interval of data) is described by the following equation.
y1(n) d(n) 1.
YN (n) d(n) eN(n) In this equation, Yi(n) (i = 1, ..., N) represents the signal outputted from the data channel despreading circuit 2 at the chip rate, and d(n) represents data of the assigned channel. Furthermore, ei(n) (i = 1, ..., N) represents the interference signal component, and N represents the spreading ratio.
A signal obtained by multiplying the signal of each chip rate and the weights wi(n) (i = 1, ..., N) in the data channel weight multiplication circuit 3 is expressed by the following equation.
yl(n) wl(n) el(n)-wl(n = d(n) . +
Y N (n) WN (n) e (n)-w (n) The output signal of the data channel signal integration circuit 4 is expressed by the following equation.
N
~ ~
y(n) = ~ Y k (n) k=l N N
= d(n) ~ wk(n) + ~ ek(n) wk( Let an error signal be defined by the following equation.
(n) = y(n) - d(n) (6) Supposing that d(n), ei(n) and wi(n) (i = 1, ..., N) are independent of each other and the average value of d(n) is 0, the mean square value of the error signal is expressed by the following equation.
- 21~617 E[E2(n)] = E[d2(n)]-E ~ wk(n)-l +E ~ ek(n)-wk(n) ,k=l , ~k=l (7) In this equation, E [ ] represents the average value.
This equation forms a surface of second degree in an N-dimensional space having wi(n) (i = 1, ..., N) as variables. The weight control circuit 9 derives weights wi(n) (i = 1, ..., N) min;mi zing the equation (7). Hereafter, an example of a method of determining the weights wi(n) (i = 1, ..., N) will be described.
FIG. 6 shows a configuration example of the weight control circuit 9. In FIG. 6, numeral 19 denotes a correlation function measuring circuit for deriving a correlation function. Numeral 20 denotes a weight calculation circuit. The operation principle of the configuration example shown in FIG. 6 will now be described. The mean square error expressed by equation (7) always assumes 0 or a positive value. When this value becomes its minimum, therefore, the weights wi(n) (i = 1, ..., N) satisfy the following condition.
aE[e (n)] = o (i = 1 N) (8) ` _ - 13 - 21~3617 By calculating equation (8), we get the following equation.
N N
5E[d (n)]. ~ E[wk(n)]-l + ~ E[ek(n)-ei(n)-Wk(n)]
= 0 (i = 1, ..., N) (9) Supposing that wi(n) (i = 1, ..., N) do not depend upon time n, equation (9) can be written in the following form.
N
~ Wk(E[d2(n)]+E[ek(n)-el(n)])=E[d (n)] (i = 1,--., N) (10) Equation (10) can be represented in a matrix form as follows:
R11 .. RN1 W.1 d = ( 1 1 ) R ... R WN - d where Rij = E[d(n)] + E[ei(n)-ej(n)] (12) Pd = E[d(n)] (13) From equation (11), we get the following equation.
W.1 R 1 1 RN1 1 d WN R 1N NN d ( 1 4 ) From equation ( 14 ), the weights wi(n) (i = 1, ..., N) can be derived. Heretofore, the case where the weights wi(n) (i = 1, ..., N) do not depend upon n has been described. Also in the case where the weights depend upon n, such as the case where the weights vary periodically, the weights can be derived in the same way. As heretofore described, the optimum values of the weights in the data channel weight multiplication circuit 3 are derived by the calculation of the correlation function of the interference signal in the correlation function measuring circuit 19 and the calculation of the inverse matrix in the weight calculation circuit 20.
FIG. 7 shows a configuration example of the weight control circuit 9. In FIG. 7, numeral 21 denotes a mean square error function gradient calculation circuit for deriving the gradient vector of ` - 15 - 2153617 the mean square error and numeral 22 denotes a weight update circuit for updating the weight on the basis of the derived gradient vector. As for the method of calculating the gradient vector and implementing the weight updating circuit, there are the steepest descent method, LMS method, learning identification method, and RLS method. They are known as algorithms of adaptive filters. Algorithms of adaptive filters are described in ~Introduction to adaptive filters~, written by S.
Haykin, translated by Takebe, and published by Gendai Kogakusha (1987), for example. In these algorithms, the weights are initialized to have appropriate values and successively converged to optimum values.
Thus in the above described first embodiment, errors of demodulated data can be reduced as shown in FIG. 8 by m;n;m; zing the interference signal in the data channel.
FIG. 9 is a block diagram showing the configuration of a second embodiment according to the present invention. Numericals 1, 2, 4, 5, 6, 7, 10 and 11 shown in FIG. 9 denote the same components as those of FIG. 2 denoted by like numerals and duplicated description of them will be omitted. In FIG. 9, numeral 12 denotes a pilot channel weight multipli-cation circuit for providing the despread pilot channelsignal with weights. Numeral 13 denotes a pilot channel interference signal component extraction _ - 16 - 2153617 circuit for extracting the interference signal component of the pilot channel from the correlatively detected pilot channel signal. Numeral 14 denotes a pilot channel weight control circuit for controlling weights in the pilot channel weight multiplication circuit 12 on the basis of the extracted interference signal component of the pilot channel.
Operation of the CDMA receiving apparatus configured as heretofore described will now be described. If a signal as shown in FIG. 3 is transmitted by a base station, the received signal 10 shown in FIG. 4 is received by the receiving apparatus.
The received signal 10 is subjected to quasi-synchronous detection in the quasi-synchronous detector circuit 1 to produce a baseband signal. This baseband signal is despread in the data channel despreading circuit 2. At this time, the despreading is performed by using a spreading sequence assigned to the data channel. The despread signal is integrated in the data channel signal integration circuit 4. By the despreading operation and integration operation heretofore described, the signal of assigned data channel can be extracted. The integrated signal contains the difference between the carrier phase of the received signal 10 and the carrier phase of the local oscillator.
On the other hand, the baseband signal outputted from the quasi-synchronous detector circuit 1 ~ - 17 - 2153617 is despread in the pilot channel despreading circuit 5.
In the signal despread in the pilot channel despreading circuit S, signal components of spreading channels other than the pilot channel and interference signal components, such as signal components of a delayed wave or a preceding wave caused by multipath propagation, are also contained besides the signal component of the pilot channel. The weights in the pilot channel weight multiplication circuit 12 are determined so that the interference signal component may be reduced to the minimum by the integrating operation in the pilot channel signal integration circuit 6. As for the method of this determination, a concept similar to the method of mi n i m; zing the interference signal component in the above described first embodiment is applied to the pilot channel. Therefore, it is only necessary to replace the data d(n) by the pilot channel signal p(n).
In the output signal of the pilot channel signal integration circuit 6, the correlatively detected pilot channel signal component and interference signal component are contained. In the pilot channel interference signal component extraction circuit 13, the interference signal component is extracted. The extraction circuit has a configuration as shown in FIG. 10, for example. In FIG. 10, numeral 23 denotes a smoothing circuit for smoothing an output signal of the pilot channel signal integration circuit -4 and numeral 24 denotes an output signal of the pilot channel signal integration circuit 4. Numeral 25 denotes a pilot channel signal after smoothing and numeral 26 denotes an extracted interference signal component. In the signal 24 (yp(t)), a signal component xp(t) of the pilot channel and an interference signal component ep(t) caused by channels other than the pilot channel or the multipath are contained. Therefore, the signal 24 can be expressed by the following equation.
yp(t) = xp(t) + ep(t) (15) In the smoothing circuit 23, the signal 24 expressed by equation (15) is smoothed. In the case where the same data already known by the receiving side are inserted into the pilot channel, xp(t) is a signal involving a change close to the carrier frequency offset. On the other hand, the interference component ep(t) is a signal having a comparatively wide bandwidth. Therefore, the interference component ep(t) is removed by the smoothing circuit 23 and the signal 25 becomes nearly equal to xp(t). Accordingly, the interference signal component 26 is derived by the following equation.
Signal 24 - signal 25 = yp(t) - xp(t) (16) = ep(t) - 19 _ 2l536l7 -As another extraction circuit, the configuration example of the interference signal component extraction circuit in the first embodiment can also be applied to the pilot channel. Data of the pilot channel is already known. In the case where estimation of the carrier phase offset and amplitude of the pilot channel is performed correctly, therefore, the interference signal component can always be detected accurately.
In the extracted interference signal component, information of spreading codes of channels other than the pilot channel and information of multipath propagation path state are contained. In the pilot channel weight control circuit 14, optimum values of the weight in the pilot channel weight multiplication circuit 2 are derived by using these kinds of information. As for the method of deriving the optimum values, the method of deriving optimum values of the weight for the data channel in the first embodiment is applied to the pilot channel.
As heretofore described, it is possible in the second embodiment to improve the estimation precision of the carrier phase offset and reduce errors of demodulated data by minimizing the interference signal component in the pilot channel. Furthermore, the transmission power of the pilot channel can be reduced while maintaining the precision of the carrier 21~3617 phase offset nearly at the same level. In addition, the power consumption can be reduced and interference for each user can be reduced.
FIG. 11 is a block diagram showing the configuration of a third embodiment according to the present invention. Numericals 1 through 14 shown in FIG. 11 denote the same components as those of FIGS. 2 and 9 denoted by like numerals. Since the configuration of the present embodiment is a combination of the first embodiment and the second embodiment, detailed description of the configuration will be omitted.
In output signals of the data channel signal integration circuit 4 and the pilot channel signal lS integration circuit 6, interference components concerning the data channel and the pilot channel are respectively minimized as disclosed in the first embodiment and the second embodiment, respectively.
Thus errors in demodulated data derived from these signals can be reduced.
As heretofore described, the present invention realizes an excellent CDMA receiving apparatus capable of improving the receiving quality by providing a circuit for providing signals after despreading with weights and by controlling the weights adaptively so as to minimize the interference signal component contained in the correlatively detected slgnal .
The present invention relates to a receiving apparatus of a communication system using a CDMA
scheme.
In recent years, demands for land mobile communication such as automobile telephone and portable telephone have significantly increased. Efficient frequency utilization techniques for assuring a larger customer capacity on a limited frequency band are increasingly important. As one of multiple access schemes for efficient frequency use, the code division multiple access (CDMA) scheme is attracting attention.
The CDMA scheme is a multiple access scheme using a spread spectrum communication technique and it is not susceptible to influence of multipath distortion. In the CDMA scheme, a diversity effect can also be anticipated because of a RAKE receiver which combines multipath components with maximal ratio combining. A
land mobile communication system using the CDMA scheme is described in U.S. Patent No. 4,901,307, for example.
In U.S. Patent No. 4,901,307, a CDMA
communication technique in the case where a plurality of users communicate via a base station is disclosed.
Such a scheme that all base stations transmit pilot ~ - 2 _ 21~ 3617 signals having the same frequency and spread codes in a CDMA system is well known. In the above described U.S.
Patent, a pilot signal is used to procure initial synchronization in a mobile device. In addition, pilot signals are used as reference of carrier phase offset and carrier frequency offset and a reference time of a frame transmitted from a base station as well.
Hereafter, the configuration of a conventional receiving apparatus for the scheme in which the pilot signals are transmitted as explained in the U.S. Patent No. 4,901, 307 will be described.
FIG. 1 is a block diagram showing the configuration of the above described conventional receiving apparatus. In FIG. 1, numeral 1 denotes a quasi-synchronous detector circuit for performing quasi-synchronous detection on a received radio frequency signal. Numeral 2 denotes a data channel despreading circuit for performing despreading by using spreading codes assigned to a data channel. Numeral 4 denotes a data channel signal integration circuit for integrating a despread data channel signal. Numeral 5 denotes a pilot channel despreading circuit for performing despreading by using spreading codes assigned to a pilot channel. Numeral 6 denotes a pilot channel signal integration circuit for integrating a despread pilot channel signal. Numeral 7 denotes a carrier phase offset correction circuit for correcting _ _ 3 _ 2153617 a carrier phase offset contained in a data channel signal. Numeral 10 denotes a received signal. Numeral 11 denotes demodulated data.
Operation of the above described conventional circuit will now be described by referring to FIG. 1.
The received signal 10 is subjected to quasi-synchronous detection in the quasi-synchronous detector circuit 1 to produce a baseband signal. This baseband signal is despread in the data channel despreading circuit 2. At this time, the despreading is performed by using a spreading sequence assigned to a data channel. The despread signal is integrated in the data channel signal integration circuit 4. By the despreading operation and integration operation, the signal of assigned data channel can be extracted. The integrated signal contains the difference between the carrier phase of the received signal 10 and the carrier phase of a local oscillator.
On the other hand, the baseband signal outputted from the quasi-synchronous detector circuit 1 is despread in the pilot channel despreading circuit 5.
At this time, the despreading is performed by using a spreading sequence assigned to a pilot channel. The despread signal is integrated in the pilot channel signal integration circuit 6. Since a signal known on the receiving side is inserted in the pilot channel, the difference between the carrier phase of the . - 4 -received signal 10 and the carrier phase of the local oscillator can be known.
In the carrier phase offset correction circuit, demodulated data 11 having a corrected carrier phase offset can be obtained by using the result of integration of the data channel signal and the result of integration of the pilot channel signal thus obtained.
In the above described conventional receiving apparatus, however, correlation levels with respect to other channel components become great because of an increased number of multiple users and multipath distortion, resulting in great interference components contained in the correlatively detected data channel signal and pilot channel signal. As a result, errors are caused in demodulated data and the communication quality is degraded. Also in the case where a narrow band interference signal is contained in the receceived signal, interference components contained in the correlatively detected data channel signal and pilot channel signal become great, resulting in degradation in communication quality.
SUMMARY OF THE INVENTION
The present invention solves the above described problems of the conventional technique. An object of the present invention is to provide a CDMA
` 2153617 _ - 5 -receiving apparatus capable of reducing errors of demodulated data and improving the receiving quality.
In accordance with the present invention, the receiving apparatus includes means for providing the signals after despreading with weights and the weights are adaptively controlled so as to m;n;m; ze the interference signal component contained in the correlatively detected signal. Thereby, the interference signal component can be reduced and the above described object is achieved.
Owing to this configuration, errors in the demodulated data are reduced and the communication quality can be improved. Furthermore, it is also possible to increase the number of users which can use the communication while maintaining the communication quality at substantially the same level. Efficient use of frequency resources can thus be realized.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram of a conventional CDMA receiving apparatus;
FIG. 2 is a block diagram of a first embodiment of a CDMA receiving apparatus according to the present invention;
FIG. 3 is a diagram showing a transmitted signal of a CDMA transmitting apparatus;
FIG. 4 is a diagram showing a received signal of a CDMA receiving apparatus;
_ - 6 - 2153617 FIG. 5 iS a block diagram of an interference signal component extracting circuit of a CDMA receiving apparatus according to the present invention;
FIG. 6 is a block diagram showing a first configuration example of a weight control circuit of a CDMA receiving apparatus according to the present nventlon;
FIG. 7 iS a block diagram showing a second configuration example of the weight control circuit of the CDMA receiving apparatus according to the present invention;
FIG. 8 iS a diagram showing demodulated data of a CDMA receiving apparatuse according to the present invention and a convention CDMA receiving apparatus;
FIG. 9 iS a block diagram of a second embodiment of a CDMA receiving apparatus according to the present invention;
FIG. 10 iS a block diagram of an interference signal component extracting circuit used in the second embodiment and a third embodiment of a CDMA receiving apparatus according to the present invention; and FIG. 11 iS a block diagram of the embodiment of a CDMA receiving apparatus according to the present lnvent lon .
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 2 is a block diagram showing the configuration of a first embodiment according to the _ 7 _ 21S3B17 -present invention. Numericals 1, 2, 4, 5, 6, 7, 10 and 11 shown in FIG. 2 denote the same components as those of FIG. 1 denoted by like numerals and duplicated description of them will be omitted. In FIG. 2, numeral 3 denotes a data channel weight multiplication circuit for providing despread data channel signals with weights. Numeral 8 denotes an interference signal component extraction circuit for extracting the interference signal component of the data channel from the correlatively detected signal component. Numeral 9 denotes a weight control circuit for controlling weights in the data channel weight multiplication circuit 3 on the basis of the extracted interference signal component of the data channel.
Operation of the CDMA receiving apparatus configured as heretofore described will now be described. If a signal as shown in FIG. 3 is transmitted by a base station, the received signal 10 shown in FIG. 4 is received by the receiving apparatus.
The received signal 10 is subjected to quasi-synchronous detection in the quasi-synchronous detector circuit 1 to produce a baseband signal. This baseband signal is despread in the data channel despreading circuit 2. In the signal despread in the data channel despreading circuit 2, signal components of spreading channels used by other users and interference signal components such as signal components of a delayed wave . 2153617 _ - 8 -or a lead wave caused by multipath propagation are also contained besides the signal component of the assigned spreading channel. Weights in the data channel weight multiplication circuit 3 are determined so that the above described interference signal component may be reduced to the minimum by the integrating operation in the data channel signal integration circuit 4. In the output signal of the data channel signal integration circuit 4, the correlatively detected data channel signal component and the correlatively detected interference signal component are contained. In the interference signal component extraction circuit 8, the correlatively detected interference signal component is extracted. In the extracted signal, information of spreading codes which are being used by other users and information of multipath propagation path state are contained.
A configuration example of the interferene signal component extraction circuit is shown in FIG. 5.
In FIG. 5, numeral 15 denotes a data judgement circuit for judging an output signal of the data channel signal integration circuit 4. Numeral 16 denotes an output signal of the data channel signal integration circuit 4. Numeral 17 denotes a signal obtained after judgement in the data judgement circuit 15. Numeral 18 denotes an extracted interference signal component.
In the signal 16, a signal component x(t) of the assigned channel and an interference component e(t) ` 2153617 g caused by other channels or multipath are contained.
Therefore, the signal 16 can be represented by the following equation.
y(t) = x(t) + e(t) (1) The data judgement circuit 15 forms a hard decision upon the soft decision value signal 16 and derives a discrete signal value of the assigned channel. If this judgement is performed correctly, the signal 17 becomes equal to x(t). Therefore, the interference signal component can be derived as represented by the following equation.
Signal 16 - Signal 17 = y(t) - x(t) = e(t) (2) In the output signal of the data channel signal integration circuit 4, the carrier phase offset is contained. When the above described judgement is to be formed, the carrier phase offset information fed from the pilot channel signal integration circuit 6 is needed.
By using the interference signal component thus derived, the weight control circuit 9 derives optimum weight values for the data channel weight multiplication circuit 3.
-- - 10 _ 21~3617 The case where minim; zation of the mean square value of the interference signal component is used as criterion for deriving the optimum value will now be described. In the output signal of the data channel despreading circuit 2, the signal of chip rate corresponding to data at time nT (where T is the transmission interval of data) is described by the following equation.
y1(n) d(n) 1.
YN (n) d(n) eN(n) In this equation, Yi(n) (i = 1, ..., N) represents the signal outputted from the data channel despreading circuit 2 at the chip rate, and d(n) represents data of the assigned channel. Furthermore, ei(n) (i = 1, ..., N) represents the interference signal component, and N represents the spreading ratio.
A signal obtained by multiplying the signal of each chip rate and the weights wi(n) (i = 1, ..., N) in the data channel weight multiplication circuit 3 is expressed by the following equation.
yl(n) wl(n) el(n)-wl(n = d(n) . +
Y N (n) WN (n) e (n)-w (n) The output signal of the data channel signal integration circuit 4 is expressed by the following equation.
N
~ ~
y(n) = ~ Y k (n) k=l N N
= d(n) ~ wk(n) + ~ ek(n) wk( Let an error signal be defined by the following equation.
(n) = y(n) - d(n) (6) Supposing that d(n), ei(n) and wi(n) (i = 1, ..., N) are independent of each other and the average value of d(n) is 0, the mean square value of the error signal is expressed by the following equation.
- 21~617 E[E2(n)] = E[d2(n)]-E ~ wk(n)-l +E ~ ek(n)-wk(n) ,k=l , ~k=l (7) In this equation, E [ ] represents the average value.
This equation forms a surface of second degree in an N-dimensional space having wi(n) (i = 1, ..., N) as variables. The weight control circuit 9 derives weights wi(n) (i = 1, ..., N) min;mi zing the equation (7). Hereafter, an example of a method of determining the weights wi(n) (i = 1, ..., N) will be described.
FIG. 6 shows a configuration example of the weight control circuit 9. In FIG. 6, numeral 19 denotes a correlation function measuring circuit for deriving a correlation function. Numeral 20 denotes a weight calculation circuit. The operation principle of the configuration example shown in FIG. 6 will now be described. The mean square error expressed by equation (7) always assumes 0 or a positive value. When this value becomes its minimum, therefore, the weights wi(n) (i = 1, ..., N) satisfy the following condition.
aE[e (n)] = o (i = 1 N) (8) ` _ - 13 - 21~3617 By calculating equation (8), we get the following equation.
N N
5E[d (n)]. ~ E[wk(n)]-l + ~ E[ek(n)-ei(n)-Wk(n)]
= 0 (i = 1, ..., N) (9) Supposing that wi(n) (i = 1, ..., N) do not depend upon time n, equation (9) can be written in the following form.
N
~ Wk(E[d2(n)]+E[ek(n)-el(n)])=E[d (n)] (i = 1,--., N) (10) Equation (10) can be represented in a matrix form as follows:
R11 .. RN1 W.1 d = ( 1 1 ) R ... R WN - d where Rij = E[d(n)] + E[ei(n)-ej(n)] (12) Pd = E[d(n)] (13) From equation (11), we get the following equation.
W.1 R 1 1 RN1 1 d WN R 1N NN d ( 1 4 ) From equation ( 14 ), the weights wi(n) (i = 1, ..., N) can be derived. Heretofore, the case where the weights wi(n) (i = 1, ..., N) do not depend upon n has been described. Also in the case where the weights depend upon n, such as the case where the weights vary periodically, the weights can be derived in the same way. As heretofore described, the optimum values of the weights in the data channel weight multiplication circuit 3 are derived by the calculation of the correlation function of the interference signal in the correlation function measuring circuit 19 and the calculation of the inverse matrix in the weight calculation circuit 20.
FIG. 7 shows a configuration example of the weight control circuit 9. In FIG. 7, numeral 21 denotes a mean square error function gradient calculation circuit for deriving the gradient vector of ` - 15 - 2153617 the mean square error and numeral 22 denotes a weight update circuit for updating the weight on the basis of the derived gradient vector. As for the method of calculating the gradient vector and implementing the weight updating circuit, there are the steepest descent method, LMS method, learning identification method, and RLS method. They are known as algorithms of adaptive filters. Algorithms of adaptive filters are described in ~Introduction to adaptive filters~, written by S.
Haykin, translated by Takebe, and published by Gendai Kogakusha (1987), for example. In these algorithms, the weights are initialized to have appropriate values and successively converged to optimum values.
Thus in the above described first embodiment, errors of demodulated data can be reduced as shown in FIG. 8 by m;n;m; zing the interference signal in the data channel.
FIG. 9 is a block diagram showing the configuration of a second embodiment according to the present invention. Numericals 1, 2, 4, 5, 6, 7, 10 and 11 shown in FIG. 9 denote the same components as those of FIG. 2 denoted by like numerals and duplicated description of them will be omitted. In FIG. 9, numeral 12 denotes a pilot channel weight multipli-cation circuit for providing the despread pilot channelsignal with weights. Numeral 13 denotes a pilot channel interference signal component extraction _ - 16 - 2153617 circuit for extracting the interference signal component of the pilot channel from the correlatively detected pilot channel signal. Numeral 14 denotes a pilot channel weight control circuit for controlling weights in the pilot channel weight multiplication circuit 12 on the basis of the extracted interference signal component of the pilot channel.
Operation of the CDMA receiving apparatus configured as heretofore described will now be described. If a signal as shown in FIG. 3 is transmitted by a base station, the received signal 10 shown in FIG. 4 is received by the receiving apparatus.
The received signal 10 is subjected to quasi-synchronous detection in the quasi-synchronous detector circuit 1 to produce a baseband signal. This baseband signal is despread in the data channel despreading circuit 2. At this time, the despreading is performed by using a spreading sequence assigned to the data channel. The despread signal is integrated in the data channel signal integration circuit 4. By the despreading operation and integration operation heretofore described, the signal of assigned data channel can be extracted. The integrated signal contains the difference between the carrier phase of the received signal 10 and the carrier phase of the local oscillator.
On the other hand, the baseband signal outputted from the quasi-synchronous detector circuit 1 ~ - 17 - 2153617 is despread in the pilot channel despreading circuit 5.
In the signal despread in the pilot channel despreading circuit S, signal components of spreading channels other than the pilot channel and interference signal components, such as signal components of a delayed wave or a preceding wave caused by multipath propagation, are also contained besides the signal component of the pilot channel. The weights in the pilot channel weight multiplication circuit 12 are determined so that the interference signal component may be reduced to the minimum by the integrating operation in the pilot channel signal integration circuit 6. As for the method of this determination, a concept similar to the method of mi n i m; zing the interference signal component in the above described first embodiment is applied to the pilot channel. Therefore, it is only necessary to replace the data d(n) by the pilot channel signal p(n).
In the output signal of the pilot channel signal integration circuit 6, the correlatively detected pilot channel signal component and interference signal component are contained. In the pilot channel interference signal component extraction circuit 13, the interference signal component is extracted. The extraction circuit has a configuration as shown in FIG. 10, for example. In FIG. 10, numeral 23 denotes a smoothing circuit for smoothing an output signal of the pilot channel signal integration circuit -4 and numeral 24 denotes an output signal of the pilot channel signal integration circuit 4. Numeral 25 denotes a pilot channel signal after smoothing and numeral 26 denotes an extracted interference signal component. In the signal 24 (yp(t)), a signal component xp(t) of the pilot channel and an interference signal component ep(t) caused by channels other than the pilot channel or the multipath are contained. Therefore, the signal 24 can be expressed by the following equation.
yp(t) = xp(t) + ep(t) (15) In the smoothing circuit 23, the signal 24 expressed by equation (15) is smoothed. In the case where the same data already known by the receiving side are inserted into the pilot channel, xp(t) is a signal involving a change close to the carrier frequency offset. On the other hand, the interference component ep(t) is a signal having a comparatively wide bandwidth. Therefore, the interference component ep(t) is removed by the smoothing circuit 23 and the signal 25 becomes nearly equal to xp(t). Accordingly, the interference signal component 26 is derived by the following equation.
Signal 24 - signal 25 = yp(t) - xp(t) (16) = ep(t) - 19 _ 2l536l7 -As another extraction circuit, the configuration example of the interference signal component extraction circuit in the first embodiment can also be applied to the pilot channel. Data of the pilot channel is already known. In the case where estimation of the carrier phase offset and amplitude of the pilot channel is performed correctly, therefore, the interference signal component can always be detected accurately.
In the extracted interference signal component, information of spreading codes of channels other than the pilot channel and information of multipath propagation path state are contained. In the pilot channel weight control circuit 14, optimum values of the weight in the pilot channel weight multiplication circuit 2 are derived by using these kinds of information. As for the method of deriving the optimum values, the method of deriving optimum values of the weight for the data channel in the first embodiment is applied to the pilot channel.
As heretofore described, it is possible in the second embodiment to improve the estimation precision of the carrier phase offset and reduce errors of demodulated data by minimizing the interference signal component in the pilot channel. Furthermore, the transmission power of the pilot channel can be reduced while maintaining the precision of the carrier 21~3617 phase offset nearly at the same level. In addition, the power consumption can be reduced and interference for each user can be reduced.
FIG. 11 is a block diagram showing the configuration of a third embodiment according to the present invention. Numericals 1 through 14 shown in FIG. 11 denote the same components as those of FIGS. 2 and 9 denoted by like numerals. Since the configuration of the present embodiment is a combination of the first embodiment and the second embodiment, detailed description of the configuration will be omitted.
In output signals of the data channel signal integration circuit 4 and the pilot channel signal lS integration circuit 6, interference components concerning the data channel and the pilot channel are respectively minimized as disclosed in the first embodiment and the second embodiment, respectively.
Thus errors in demodulated data derived from these signals can be reduced.
As heretofore described, the present invention realizes an excellent CDMA receiving apparatus capable of improving the receiving quality by providing a circuit for providing signals after despreading with weights and by controlling the weights adaptively so as to minimize the interference signal component contained in the correlatively detected slgnal .
Claims (41)
1. A receiving apparatus of a communication system using a CDMA (code division multiple access) scheme comprising:
a quasi-synchronous detector circuit for performing quasi-synchronous detection on a received signal;
data channel despreading means for performing despreading on a signal subjected to the quasi-synchronous detection by using spreading codes assigned to a data channel;
data channel weight multiplication means for providing a despread data channel signal with weights;
data channel signal integration means for integrating a weighted data channel signal;
pilot channel despreading means for performing despreading on an output signal of said quasi-synchronous detector circuit by using spreading codes assigned to a pilot channel;
pilot channel signal integration means for integrating a despread pilot channel signal;
carrier phase offset correction means for generating a data channel signal corrected in carrier phase offset by using an output signal of said data channel signal integration means and an output signal of said pilot channel signal integration means;
interference signal component extraction means for extracting an interference signal component from the output signal of said data channel signal integration means; and weight control means for determining the weights in said data channel weight multiplication means on the basis of an extracted interference signal component.
a quasi-synchronous detector circuit for performing quasi-synchronous detection on a received signal;
data channel despreading means for performing despreading on a signal subjected to the quasi-synchronous detection by using spreading codes assigned to a data channel;
data channel weight multiplication means for providing a despread data channel signal with weights;
data channel signal integration means for integrating a weighted data channel signal;
pilot channel despreading means for performing despreading on an output signal of said quasi-synchronous detector circuit by using spreading codes assigned to a pilot channel;
pilot channel signal integration means for integrating a despread pilot channel signal;
carrier phase offset correction means for generating a data channel signal corrected in carrier phase offset by using an output signal of said data channel signal integration means and an output signal of said pilot channel signal integration means;
interference signal component extraction means for extracting an interference signal component from the output signal of said data channel signal integration means; and weight control means for determining the weights in said data channel weight multiplication means on the basis of an extracted interference signal component.
2. A CDMA receiving apparatus according to Claim 1, wherein the interference signal component extraction means comprises:
data judgement means for performing a hard decision upon a soft decision value signal outputted from the data channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the data channel signal integration means and outputting the interference signal component.
data judgement means for performing a hard decision upon a soft decision value signal outputted from the data channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the data channel signal integration means and outputting the interference signal component.
3. A CDMA receiving apparatus according to Claim 1, wherein the weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
4. A CDMA receiving apparatus according to Claim 2, wherein the weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
5. A CDMA receiving apparatus according to Claim 1, wherein the weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
6. A CDMA receiving apparatus according to Claim 2, wherein the weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
7. A receiving apparatus of a communication system using a CDMA (code division multiple access) scheme comprising:
a quasi-synchronous detector circuit for performing quasi-synchronous detection on a received signal;
data channel despreading means for performing despreading on a signal subjected to the quasi-synchronous detection by using spreading codes assigned to a data channel;
data channel signal integration means for integrating a despread data channel signal;
pilot channel despreading means for performing despreading on an output signal of said quasi-synchronous detector circuit by using spreading codes assigned to a pilot channel;
pilot channel weight multiplication means for providing a despread polot channel signal with weights;
pilot channel signal integration means for integrating a weighted pilot channel signal;
carrier phase offset correction means for generating a data channel signal corrected in carrier phase offset by using an output signal of said data channel signal integration means and an output signal of said pilot channel signal integration means;
pilot channel interference signal component extraction means for extracting an interference signal component in the pilot channel from the output signal of said pilot channel signal integration means; and pilot channel weight control means for determining the weights in said pilot channel weight multiplication means on the basis of the interference signal component in the pilot channel.
a quasi-synchronous detector circuit for performing quasi-synchronous detection on a received signal;
data channel despreading means for performing despreading on a signal subjected to the quasi-synchronous detection by using spreading codes assigned to a data channel;
data channel signal integration means for integrating a despread data channel signal;
pilot channel despreading means for performing despreading on an output signal of said quasi-synchronous detector circuit by using spreading codes assigned to a pilot channel;
pilot channel weight multiplication means for providing a despread polot channel signal with weights;
pilot channel signal integration means for integrating a weighted pilot channel signal;
carrier phase offset correction means for generating a data channel signal corrected in carrier phase offset by using an output signal of said data channel signal integration means and an output signal of said pilot channel signal integration means;
pilot channel interference signal component extraction means for extracting an interference signal component in the pilot channel from the output signal of said pilot channel signal integration means; and pilot channel weight control means for determining the weights in said pilot channel weight multiplication means on the basis of the interference signal component in the pilot channel.
8. A CDMA receiving apparatus according to Claim 7, wherein the pilot channel interference signal component extraction means comprises:
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting an interference signal component.
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting an interference signal component.
9. A CDMA receiving apparatus according to Claim 7, wherein the pilot channel interference signal component extraction means comprises:
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
10. A CDMA receiving apparatus according to Claim 7, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
11. A CDMA receiving apparatus according to Claim 8, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
12. A CDMA receiving apparatus according to Claim 9, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
13. A CDMA receiving apparatus according to Claim 7, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
14. A CDMA receiving apparatus according to Claim 8, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
15. A CDMA receiving apparatus according to Claim 9, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
16. A CDMA receiving apparatus according to Claim 1, further comprising:
pilot channel weight multiplication means for providing a despread pilot channel signal with weights;
pilot channel interference signal component extraction means for extracting an interference signal component in the pilot channel; and pilot channel weight control means for determining the weights in said pilot channel weight multiplication means on the basis of the interference signal component in the pilot channel.
pilot channel weight multiplication means for providing a despread pilot channel signal with weights;
pilot channel interference signal component extraction means for extracting an interference signal component in the pilot channel; and pilot channel weight control means for determining the weights in said pilot channel weight multiplication means on the basis of the interference signal component in the pilot channel.
17. A CDMA receiving apparatus according to Claim 16, wherein the interference signal component extraction means comprises:
data judgement means for performing a hard decision upon a soft decision value signal outputted from the data channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the data channel signal integration means and outputting the interference signal component.
data judgement means for performing a hard decision upon a soft decision value signal outputted from the data channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the data channel signal integration means and outputting the interference signal component.
18. A CDMA receiving apparatus according to Claim 16, wherein the weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
19. A CDMA receiving apparatus according to Claim 17, wherein the weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
20. A CDMA receiving apparatus according to Claim 16, wherein the weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
21. A CDMA receiving apparatus according to Claim 17, wherein the weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
22. A CDMA receiving apparatus according to Claim 16, wherein the pilot channel interference signal component extraction means comprises:
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
23. A CDMA receiving apparatus according to Claim 17, wherein the pilot channel interference signal component extraction means comprises:
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
24. A CDMA receiving apparatus according to Claim 19, wherein the pilot channel interference signal component extraction means comprises:
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
25. A CDMA receiving apparatus according to Claim 21, wherein the pilot channel interference signal component extraction means comprises:
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
data judgement means for performing a hard decision upon a soft decision value outputted from the pilot channel signal integration means and deriving a discrete signal value of an assigned channel; and computation means for subtracting a discrete signal outputted from the data judgement means from the soft decision value signal outputted from the pilot channel signal integration means and outputting the interference signal component.
26. A CDMA receiving apparatus according to Claim 16, wherein the pilot channel interference signal component extraction means comprises:
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
27. A CDMA receiving apparatus according to Claim 17, wherein the pilot channel interference signal component extraction means comprises:
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
28. A CDMA receiving apparatus according to Claim 19, wherein the pilot channel interference signal component extraction means comprises:
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
29. A CDMA receiving apparatus according to Claim 21, wherein the pilot channel interference signal component extraction means comprises:
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
smoothing means for smoothing a signal outputted from the pilot channel signal integration means; and computation means for subtracting a signal outputted from the smoothing means from the signal outputted from the pilot channel signal integration means and outputting an interference signal component.
30. A CDMA receiving apparatus according to Claim 16, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
31. A CDMA receiving apparatus according to Claim 17, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
32. A CDMA receiving apparatus according to Claim 19, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
33. A CDMA receiving apparatus according to Claim 21, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
34. A CDMA receiving apparatus according to Claim 25, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
35. A CDMA receiving apparatus according to Claim 29, wherein the pilot channel weight control means comprises:
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
correlation function measuring means for calculating a correlation function of an interference signal outputted from the pilot channel interference signal component extraction means; and weight calculation means for calculating an inverse matrix of a signal outputted from the correlation function measuring means.
36. A CDMA receiving apparatus according to Claim 16, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
37. A CDMA receiving apparatus according to Claim 17, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
38. A CDMA receiving apparatus according to Claim 19, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
39. A CDMA receiving apparatus according to Claim 21, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
40. A CDMA receiving apparatus according to Claim 25, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
41. A CDMA receiving apparatus according to Claim 29, wherein the pilot channel weight control means comprises:
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
mean square error function gradient calculation means for deriving a gradient vector of a mean square error; and weight update means for updating weights on the basis of the gradient vector derived by the mean square error function gradient calculation means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16177694 | 1994-07-14 | ||
| JP06-161776 | 1994-07-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2153617A1 true CA2153617A1 (en) | 1996-01-15 |
Family
ID=15741696
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002153617A Abandoned CA2153617A1 (en) | 1994-07-14 | 1995-07-11 | Cdma receiving apparatus |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR0160187B1 (en) |
| CN (1) | CN1120270A (en) |
| CA (1) | CA2153617A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2934185B2 (en) * | 1996-03-15 | 1999-08-16 | 松下電器産業株式会社 | CDMA cellular radio base station apparatus, mobile station apparatus, and transmission method |
| KR20000034517A (en) * | 1998-11-30 | 2000-06-26 | 전주범 | Detect circuit of jamming frequency of code division multiple access system |
| KR100868440B1 (en) * | 2002-07-03 | 2008-11-11 | 주식회사 포스코 | Apparatus for controlling exhaust gas of pulverizer coal production equipment of blast furence |
| CN104813602B (en) * | 2013-01-03 | 2018-08-07 | 英特尔公司 | For the cross-carrier accurate device and method with bit signaling in new carrier type (NCT) wireless network |
| JP7146878B2 (en) * | 2020-11-19 | 2022-10-04 | フラウンホッファー－ゲゼルシャフト ツァ フェルダールング デァ アンゲヴァンテン フォアシュンク エー．ファオ | Optimized Preamble and Method for Interference Robust Packet Detection for Telemetry Applications |
-
1995
- 1995-07-11 CA CA002153617A patent/CA2153617A1/en not_active Abandoned
- 1995-07-13 CN CN95109974A patent/CN1120270A/en active Pending
- 1995-07-13 KR KR1019950020590A patent/KR0160187B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR0160187B1 (en) | 1998-12-01 |
| KR960006369A (en) | 1996-02-23 |
| CN1120270A (en) | 1996-04-10 |
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