JP2004304412A - Demodulator in mobile communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an accurate channel estimate to improve accuracy of a demodulated signal by calculating the channel estimate of an optimal averaged symbol number through simple arithmetic processing for noise superimpose and random phase fluctuation on a wireless transmission line concerning a demodulator in a mobile communication device. <P>SOLUTION: Channel estimate calculation parts 1-1 (#1, #2..., #n) are provided for respectively calculating, for a symbol to be demodulated, a plurality of channel estimates 1-10 of different averaging times (channel estimation reference symbol extraction blocks) for channel estimation, a correlative value calculation part 1-13 calculates, for each of the plurality of channel estimates, correlative values between averaged channel estimates 1-11 of the first half and averaged channel estimates 1-12 of the second half, and the correlative values are compared by a comparing part 1-3. The channel estimate of the highest correlative value is selected by a selecting part 1-2, and the channel estimate is used for imparting phase rotation for channel compensation to a received symbol and for demodulating the symbol. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a demodulator in a mobile communication device, transmits a known signal to a part of a common channel or an individual channel, performs channel estimation based on the received known signal, and performs synchronous detection using the estimated value as a reference phase. The demodulator to perform.
[0002]
3GPP (3), a third generation standard for mobile communications^rd  In the specifications of the Generation Partnership Project, a direct sequence code division multiple access (DS) CDMA transmission system capable of separating user signals, reducing interference between base stations, and multipath separation is employed, and the phase of an individual channel is adopted. In this system, a common pilot channel (CPICH: Common Pilot Channel) is transmitted as a phase reference for demodulating a modulated signal.
[0003]
In a mobile communication environment, random phase fluctuation due to fading frequently occurs, and it is difficult to generate a demodulation reference phase by carrier recovery in a phase modulation method. Therefore, in the CDMA transmission system, means for code-multiplexing or time-multiplexing a signal of a known phase together with a data signal and transmitting the signal and demodulating the data signal using the phase as a reference phase is used.
[0004]
FIG. 8 shows a block configuration of a mobile communication device to which the demodulator of the present invention is applied. In the figure, 8-1 is an antenna, 8-2 is a duplexer, 8-3 is a low noise amplifier, 8-4 is an analog-to-digital converter, 8-5 is a searcher for detecting a path, and 8-6 is a demodulation of a received signal. 8-7 decodes the demodulated received signal and encodes / decodes the transmitted signal, 8-8 controls the controller, and 8-9 modulates the encoded transmitted signal. 8-10 is a digital-to-analog converter, and 8-11 is a power amplifier. The present invention particularly relates to the configuration of the demodulation unit 8-6 shown in FIG.
[Prior art]
[0005]
FIG. 9 shows a configuration of a conventional demodulation unit. The despreading unit 9-1 in the figure despreads the dedicated channel at the path timing notified from the searcher. The despreading unit 9-2 despreads the common pilot channel at the same timing, and the channel estimating unit 9-3 averages the despread signal of the common pilot channel, thereby obtaining a signal near the symbol of the individual channel to be demodulated. Detect the reference phase. The individual channel is phase-rotated and detected by the multiplier 9-4 using the channel estimation value as a reference phase.
[0006]
The detection result is output as a demodulated signal through a RAKE combining unit 9-5 that combines the multipath received signals to increase the gain. A plurality of dedicated channel despreading units 9-1, common pilot channel despreading units 9-2, channel estimating units 9-3, and multipliers 9-4 are provided for each multipath path. .
[0007]
In mobile communication, noise is added on a wireless transmission path and signal quality deteriorates. However, by averaging a plurality of received symbols, an effect of noise removal can be obtained. On the other hand, if the received symbols are averaged for a long time, random phase fluctuations cannot be ignored. Therefore, there is a trade-off between the averaging time for noise removal and the accuracy of phase detection.
[0008]
The phase fluctuation occurs at a frequency proportional to the moving speed of the moving object. Therefore, there is a technique for measuring the speed of a moving object and determining the number of averaged symbols of the common pilot channel according to the moving speed. FIG. 10 shows a configuration in which the speed detection function is provided in the demodulation unit. In the figure, a speed detector 10-1 detects the speed of a moving object, and provides the speed information to a channel estimator 9-3. The channel estimator 9-3 determines the number of averaged symbols of the common pilot channel according to the speed information, and calculates a channel estimation value.
[0009]
Prior art documents related to the present invention include the following documents. The following Patent Document 1 describes a technique for obtaining a correct channel estimation value by obtaining a correlation with a known symbol pattern and selecting a signal of a symbol pattern having the highest correlation. Reference 2 discloses an invention relating to multipath path selection of a CDMA receiving apparatus.
[0010]
Patent Literature 3 describes a technique of calculating a channel estimation value (carrier phase) using past data, and a technique of selecting an individual channel and a common pilot based on a certain criterion. Patent Literature 4 describes a technique relating to timing detection of a path for detecting a multipath. Patent Literature 5 describes a technique for suppressing a processing delay, which is a problem of the interference canceller technique, by obtaining a channel estimation value at an optimal timing.
[0011]
Patent Literature 6 describes a technique for dynamically changing the weight of channel estimation based on a level measurement value and the number of level crossings. Patent Literature 7 describes a technique of using a plurality of pilot symbols for channel estimation, weighting them, and improving the accuracy of a channel estimation value. Patent Literature 8 discloses a technique for improving the accuracy of a channel estimation value by using a pilot symbol portion of a broadcast signal that will have a large transmission power. Patent Document 9 discloses a technique of preparing a plurality of reference phases, comparing the reference phase with the phase of a received signal, and updating the selection of the reference phase.
[0012]
[Patent Document 1]
JP 2000-324017 A
[Patent Document 2]
Japanese Patent No. 2870526
[Patent Document 3]
JP 2002-57601 A
[Patent Document 4]
JP-A-2002-94584
[Patent Document 5]
JP-A-10-190494
[Patent Document 6]
JP 2001-267960 A
[Patent Document 7]
JP-A-10-51424
[Patent Document 8]
JP 2000-252960 A
[Patent Document 9]
JP-A-7-273712
[0013]
[Problems to be solved by the invention]
When determining the number of symbols to be averaged for the common pilot channel according to the moving speed described above, several speed detections are performed, such as estimating the Doppler frequency from fluctuations in the amplitude of the received signal and the phase of the demodulated signal and detecting the moving speed. However, any of the methods requires dedicated arithmetic processing for speed detection, and the processing amount is greatly increased.
[0014]
Furthermore, when speed detection is performed with high accuracy, more sample signals are required, and it is difficult to apply the present invention to an intermittent reception standby operation or the like of a mobile communication terminal in which low power consumption is an essential requirement. . Further, when determining the number of averaged symbols at the moving speed, since the signal quality that changes in accordance with the strength of the received signal is not considered, for example, when stationary just below the base station, sufficient In spite of the situation where good signal quality is obtained with a strong received signal, unnecessary power may be consumed by selecting an unnecessary average number of symbols and performing arithmetic processing. .
[0015]
The present invention improves the accuracy of a demodulated signal by calculating a channel estimation value of the optimum number of averaged symbols by a simple operation, obtaining a highly accurate channel estimation value, and demodulating using the channel estimation value. The purpose is to let them.
[0016]
[Means for Solving the Problems]
The demodulator in the mobile communication device according to the present invention includes: (1) a demodulator that performs channel estimation using a known signal time-multiplexed on a common channel or an individual channel and performs synchronous detection using the channel estimation value; Channel estimation value calculating means for calculating a plurality of channel estimation values having different averaging times for the target symbol, and for each of the plurality of channel estimation values, a reference symbol within the averaging time is divided into a first half and a second half. And a correlation value calculating means for calculating a correlation value between the averaged channel estimation value in the first half and the averaged channel estimation value in the second half, and comparing the correlation values calculated by the correlation value calculating means with each other. A channel estimation value selecting means for selecting a channel estimation value having the highest correlation value; and a channel estimation value selected by the channel estimation value selecting means, and Giving rotation to the received symbol is obtained and a means for demodulating.
[0017]
(2) The channel estimation value calculation means prepares a plurality of channel estimation values having different numbers of reference symbols, weights each reference symbol in the time axis direction, and the correlation value calculation means , For each of the weighted reference symbols, a correlation value between the averaged channel estimation value of the first half and the averaged channel estimation value of the second half is calculated.
[0018]
Further, (3) the channel estimation value calculating means is provided for each path in a multipath environment, a path selecting means for selecting a path having the highest power among the paths, and a path selected by the path selecting means. Correlation value for calculating a correlation value between the averaged channel estimation value of the first half and the averaged channel estimation value of the second half for each of the plurality of channel estimation values calculated by the channel estimation value calculating means Calculating means, comparing each correlation value calculated by the correlation value calculating means with each other, and comprising a channel estimation value selecting means for selecting a channel estimation value with the highest correlation value, the channel estimation value selecting means, The channel estimation value having the same averaging time as the channel estimation value selected in the path with the highest power is selected from a plurality of channel estimation values in other paths.
[0019]
(4) The channel estimation value calculation means is provided for each path in a multipath environment, and for each of a plurality of channel estimation values calculated by the channel estimation value calculation means, the first half channel estimation from all paths is performed. A correlation value calculating means for calculating a correlation value between the value and the channel estimation value in the second half, and comparing the correlation values calculated by the correlation value calculating means with each other, and estimating a channel at an averaging time having the highest correlation value. A comparison means for designating a value, and a channel estimation value selection means for each path for selecting a channel estimation value of the averaging time designated by the comparison means.
[0020]
Further, the accuracy can be further improved by detecting statistical propagation path properties. The demodulator in the mobile communication device of the present invention, which selects based on the result of integrating correlation values of a plurality of timings separated from each other in time, comprises: Channel estimation value calculating means for calculating a plurality of channel estimation values different from each other, and for each of a plurality of channel estimation values having different averaging times calculated by the channel estimation value calculation means, A correlation value calculating unit that calculates a correlation value between the first half and the second half, and comparing the correlation values calculated by the correlation value calculating unit with each other to indicate a channel estimation value of an averaging time having the highest correlation value. And a channel estimation value selection means for selecting a channel estimation value of the averaging time specified by the comparison means.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a basic configuration of a demodulator according to the present invention. The despreading unit 9-1 despreads the individual channel at the path timing notified from the searcher as in the demodulator of FIG. 9, and the despreading unit 9-2 despreads the common pilot channel at the same timing. The channel estimation calculation unit 1-1 (# 1, # 2,..., #N) of the present invention calculates a plurality of (n) in order to calculate a plurality of channel estimation values having different numbers of reference symbols in the averaging process. , And a despread signal of the common pilot channel is input to each channel estimation calculation unit 1-1 (# 1, # 2,..., #N).
[0022]
In each of the channel estimation calculation sections 1-1 (# 1, # 2,..., #N), a predetermined reference symbol is obtained by the channel estimation section 1-10 based on the despread signal of the known signal of the common pilot channel. In addition to calculating the channel estimation value obtained by performing the averaging operation on the basis of the number, the channel estimation first half 1-11 calculates the channel estimation value from the reference symbols of the first half of the predetermined number of reference symbols, and calculates the channel estimation second half 1- 1 In 12, the channel estimation value is calculated from the reference symbols in the latter half of the predetermined number of reference symbols.
[0023]
The channel estimation values from the first half of channel estimation 1-11 and the second half of channel estimation 1-12 are input to the correlation calculator 1-13, and the correlation calculator 1-13 performs channel estimation from the first half of channel estimation 1-11. The correlation between the value and the channel estimation value from the second half of channel estimation 1-12 is calculated, and the value is output to comparison section 1-3.
[0024]
The comparing section 1-3 compares the correlation values of the first half of the channel estimation and the second half of the channel estimation input from the channel estimation calculating sections 1-1 (# 1, # 2,..., #N). , The channel estimation calculating section 1-1 having the highest correlation value (any of # 1, # 2,..., #N) is selected, and the channel estimation calculating section 1-1 (# 1, # 2) is selected. ,..., #N) is output to the selection unit 1-2.
[0025]
The selecting unit 1-2 receives a signal from the channel estimating unit 1-10 of the channel estimation calculating unit 1-1 (any of # 1, # 2,..., #N) instructed by the comparing unit 1-3. The output channel estimation value is selected, and the channel estimation value is output to the multiplier 9-4. Using the channel estimation value as a reference phase, the individual channel is phase-rotated and detected by the multiplier 9-4 to obtain a demodulated signal.
[0026]
In this way, a plurality (n) of channel estimation values having different reference symbol extraction sections (averaging times) for channel estimation are calculated, and the channel estimation values are divided into a first half and a second half. By calculating the correlation value with the section and selecting the channel estimation value with the highest correlation value, the highest quality channel estimation value can be used as a reference phase for demodulation, and the reliability of the demodulated signal can be increased.
[0027]
When the channel fluctuation is large, the correlation value between the first half and the second half becomes higher as the averaging time is shorter, and when there is much noise, the correlation between the first half and the latter half becomes longer as the averaging time becomes longer. If both influences are present, the correlation value above includes each element.The channel estimation value with the highest correlation value in the first half and the second half can be regarded as the one with the highest accuracy, and A channel estimation value with a high value may be selected.
[0028]
FIG. 2 shows an embodiment in which channel estimation values having different numbers of averaged reference symbols are prepared as a plurality of channel estimation values. This is an example where the number of averaged common pilot symbols is used as a parameter. This can be realized with a simple configuration as compared with the weighting method.
[0029]
An example of the correlation calculation processing is shown below. The first half average value of the channel estimation value of the first averaged reference symbol number is (I_a1, Q_a1), And the latter half average value is (I_b1, Q_b1), The first half average value of the channel estimation value of the second averaged reference symbol number is (I_a2, Q_a2), And the latter half average value is (I_b2, Q_b2), The correlation value R (# 1) between the first half and the second half of the channel estimation value of the first averaged reference symbol number is represented by the following equation.
[0030]
R (# 1) = (I_a1× I_b1+ Q_a1× Q_b1) / Sqr ｛(I_a1 ²+ Q_a1 ²) (I_b1 ²+ Q_b1 ²)｝
[0031]
The correlation value R (# 2) between the first half and the second half of the channel estimation value of the second averaged reference symbol number is represented by the following equation.
R (# 2) = (I_a2× I_b2+ Q_a2× Q_b2) / Sqr ｛(I_a2 ²+ Q_a2 ²) (I_b2 ²+ Q_b2 ²)｝
Here, sqr is the square root (√). The same applies to the following equations.
[0032]
FIG. 3 shows an embodiment in which, as a plurality of channel estimation values, different numbers of averaged reference symbols are used, and different reference symbols are weighted differently in the time axis direction. Since a reference symbol closer in time to a symbol to be demodulated (a symbol to be demodulated) has a higher phase correlation, a reference symbol closer to the center is weighted more heavily to obtain a highly accurate channel estimation value. Can be.
[0033]
However, since the optimum value of the weighting coefficient changes depending on the change in the moving speed and the noise power, it is also effective to prepare several models of the weighting coefficient and calculate the optimum value in advance. Although the weighting coefficient is basically a scalar, the effectiveness of vectorization is not denied.
[0034]
An example of the correlation calculation process according to the second embodiment will be described below. The weighted first half average value of the channel estimation value of the first averaged reference symbol number is (I ′_a1, Q '_a1), And the latter half average is (I '_b1, Q '_b1), The first half average value of the channel estimation value of the second averaged reference symbol number is (I ′)_a2, Q '_a2), And the latter half average is (I '_b2, Q '_b2), The correlation value Rw between the first half and the second half of the channel estimation value of the first averaged reference symbol number is represented by the following equation.
[0035]
Rw (# 1) = (I '_a1× I '_b1+ Q '_a1× Q '_b1) / Sqr ｛(I ’_a1 ²+ Q '_a1 ²) (I '_b1 ²+ Q '_b1 ²)｝
[0036]
Further, the correlation value Rw (# 2) between the first half and the second half of the channel estimation value of the second averaged reference symbol number is represented by the following equation.
Rw (# 2) = (I '_a2× I '_b2+ Q '_a2× Q '_b2) / Sqr ｛(I ’_a2 ²+ Q '_a2 ²) (I '_b2 ²+ Q '_b2 ²)｝
[0037]
FIG. 4 shows an embodiment in which a channel estimation value is independently selected for each path in a multipath environment. Means for selecting a channel estimation value having the highest correlation value similar to the configuration shown in FIG. 1 for each path, independently selecting a channel estimation value for each path, and demodulating each path detected with the estimation value The signal is input to the RAKE combining section 9-5, combined and output as a demodulated signal. The channel estimation value selection means for each path in FIG. 4 is the same as the configuration shown in FIG. 1, and therefore, the same components as those in FIG.
[0038]
In the multipath environment shown in FIG. 5, the channel estimation value of the path having the highest power is selected from the reception signals of the multipath, and the channel estimation value having the highest correlation between the first half and the second half thereof is selected. An example in which the averaging time (number of reference symbols) of channel estimation is selected as the averaging time (number of reference symbols) of channel estimation of another path will be described.
[0039]
In FIG. 5, a plurality of channel estimation values having different averaging times (the number of reference symbols) are calculated for each path. Then, the output of the despreading unit 9-2 of the common pilot channel of each path is input to the power comparison / maximum selection unit 5-1. Is selected, and the channel estimation value having the highest correlation value between the first half and the second half is selected by the selection unit 5-2 from among the plurality of channel estimation values for the path, as in the above-described embodiment.
[0040]
The selection unit 1 of each of the other paths supplies an instruction signal for instructing selection of a channel estimation value of the same averaging time (number of reference symbols) as the channel estimation value selected by the selection unit 5-2 for other paths. -2, and the selector 1-2 of each path selects a channel estimation value according to the instruction signal.
[0041]
In a multipath environment, the averaging time (the number of reference symbols) is determined using the channel estimation value of the path having the strongest power that has the greatest effect on the quality after RAKE combining, and the other paths have the highest power. Although it is expected that the performance will be slightly degraded by following the determination on the strong path, the processing for calculating the correlation value is performed only on one path, so that the amount of calculation processing can be significantly reduced.
[0042]
FIG. 6 shows the correlation between the first half and the second half over the entire path for each channel estimation value of the same averaging time (number of reference symbols) for each channel estimation value calculated for each path in a multipath environment. An example in which a value is calculated and a channel estimation value of the averaging time (the number of reference symbols) having the highest correlation value is selected will be described.
[0043]
In FIG. 6, a channel estimation calculator 1-1 (# 1, # 2) for calculating a plurality of channel estimation values having different averaging times (number of reference symbols) is provided for each path. The first half and the second half of a plurality of channel estimation values having different averaging times (the number of reference symbols) from each path are output to correlation calculation units 6-1 and 6-2 corresponding to the plurality of channel estimation values.
[0044]
The correlation calculators 6-1 and 6-2 corresponding to a plurality of channel estimation values respectively input the first half and the second half of the channel estimation value from each path, and calculate their correlation values. The correlation values calculated by the correlation calculation units 6-1 and 6-2 are compared in magnitude by the comparison unit 1-3, and the channel estimation value of the highest averaging time (the number of reference symbols) of the correlation value is selected. Then, an instruction signal is sent to the selection unit 1-2 of each path.
[0045]
An example of the correlation processing in the correlation calculators 6-1 and 6-2 corresponding to a plurality of channel estimation values will be described below. For the first path, the first half average value of the channel estimation value of the first averaging time (the number of reference symbols) is represented by (I_p1a1, Q_p1a1), And the latter half average value is (I_p1b1, Q_p1b1), The first half average value of the channel estimation value of the second averaging time (the number of reference symbols) is (I_p1a2, Qp1a2), and calculate the latter half average value by (I_p1b2, Q_p1b2).
[0046]
Further, for the second path, the first half average value of the channel estimation value of the first averaging time (the number of reference symbols) is represented by (I_p2a1, Q_p2a1), And the latter half average value is (I_p2b1, Q_p2b1), The first half average value of the channel estimation value of the second averaging time (the number of reference symbols) is (I_p2a2, Q_p2a2), And the latter half average value is (I_p2b2, Q_p2b2).
[0047]
The correlation value Rp (# 1) between the first half and the second half of the first averaging time (the number of reference symbols) is represented by the following equation.
Rp (# 1) = ｛(I_p1a1× I_p1b1+ Q_p1a1× Q_p1b1) + (I_p2a1× I_p2b1+ Q_p2a1× Q_p2b1)｝ / Sqr ｛(I_p1a1 ²+ Q_p1a1 ²+ I_p2a1 ²+ Q_p2a1 ²) (I_p1b1 ²+ Q_p1b1 ²+ I_p2b1 ²+ Q_p2b1 ²)｝
[0048]
The correlation value Rp (# 2) between the first half and the second half of the second averaging time (the number of reference symbols) is as follows by replacing a1 in the above equation with a2 and b1 with b2.
Rp (# 2) = ｛(I_p1a2× I_p1b2+ Q_p1a2× Q_p1b2) + (I_p2a2× I_p2b2+ Q_p2a2× Q_p2b2)｝ / Sqr ｛(I_p1a2 ²+ Q_p1a2 ²+ I_p2a2 ²+ Q_p2a2 ²) (I_p1b2 ²+ Q_p1b2 ²+ I_p2b2 ²+ Q_p2b2 ²)｝
[0049]
FIG. 7 shows an embodiment in which an optimum reference symbol extraction section (averaging time) for channel estimation is selected for each path using correlation values of a plurality of channel estimation value samples having different timings. Each channel estimation calculating section 1-1 (# 1, # 2) holds a plurality of channel estimation value samples at different timings, and therefore calculates a correlation value between the first half average value and the second half average value of the channel estimation value at each timing. A memory / averaging unit 7-2 for temporarily storing the data is provided.
[0050]
The correlation value obtained by averaging the timings is input to the comparison unit 1-3. The comparing section 1-3 compares the correlation values input from the respective channel estimation calculating sections 1-1 (# 1, # 2) in magnitude, and selects a channel estimation value having the highest correlation value among them. An instruction signal is output to 1-2. The selector 1-2 selects a channel estimation value according to the instruction signal.
[0051]
An example of the correlation calculation process in the correlation calculator 7-1 is shown below. First, for the channel estimation value at the first sample timing t1, the first half average value after weighting the channel estimation value of the first averaging time (the number of reference symbols) is (I_a1t1, Q_a1t1), And the latter half average value is (I_b1t1, Q_b1t1), The weighted first half average value of the channel estimation value of the second averaging time (the number of reference symbols) is (I_a2t1, Q_a2t1), And the latter half average value is (I_b2t1, Q_b2t1).
[0052]
For the channel estimation value at the second sample timing t2, the first half average value after weighting the channel estimation value of the first averaging time (the number of reference symbols) is (I_a1t2, Q_a1t2), And the latter half average value is (I_b1t2, Q_b1t2), The weighted first half average value of the channel estimation value of the second averaging time (the number of reference symbols) is (I_a2t2, Q_a2t2), And the latter half average value is (I_b2t2, Q_b2t2).
[0053]
The correlation value Rt (# 1) between the first half and the second half of the channel estimation value of the first averaging time (the number of reference symbols) is represented by the following equation.
Rt (# 1) = (I_a1t1× I_b1t1+ Q_a1t1× Q_b1t1) / Sqr ｛(I_a1t1 ²+ Q_a1t1 ²) (I_b1t1 ²+ Q_b1t1 ²)｝ + (I_a1t2× I_b1t2+ Q_a1t2× Q_b1t2) / Sqr ｛(I_a1t2 ²+ Q_a1t2 ²) (I_b1t2 ²+ Q_b1t2 ²｝
[0054]
The correlation value Rt (# 2) between the first half and the second half of the channel estimation value of the second averaging time (the number of reference symbols) is obtained by replacing a1 in the above equation with a2 and b1 with b2. Become.
Rt (# 2) = (I_a2t1× I_b2t1+ Q_a2t1× Q_b2t1) / Sqr ｛(I_a2t1 ²+ Q_a2t1 ²) (I_b2t1 ²+ Q_b2t1 ²)｝ + (I_a2t2× I_b2t2+ Q_a2t2× Q_b2t2)｝ / Sqr ｛(I_a2t2 ²+ Q_a2t2 ²) (I_b2t2 ²+ Q_b2t2 ²)｝
[0055]
The present invention is not limited to the embodiments described above, and various combinations can be added without departing from the spirit of the present invention by appropriately combining channel estimation value selecting means of each embodiment.
[0056]
(Supplementary Note 1) In a demodulator that performs channel estimation using a known signal time-multiplexed on a common channel or an individual channel, and performs synchronous detection using the channel estimation value, an averaging time is calculated for a symbol to be demodulated. Channel estimation value calculating means for calculating a plurality of channel estimation values different from each other, and for each of the plurality of channel estimation values, dividing a reference symbol within an averaging time into a first half and a second half, A correlation value calculating means for calculating a correlation value between the estimated value and the averaged channel estimation value in the second half, and comparing the correlation values calculated by the correlation value calculating means with each other to obtain a channel estimation value having the highest correlation value And demodulating the received symbol by applying a phase rotation for channel compensation to the received symbol using the channel estimation value selecting means for selecting Demodulator in a mobile communication apparatus characterized by comprising a that means.
(Supplementary Note 2) The channel estimation value calculation means prepares a plurality of channel estimation values having different numbers of reference symbols, weights each reference symbol in the time axis direction, and the correlation value calculation means The movement according to claim 1, characterized in that the weighted reference symbols are configured to calculate a correlation value between the first half averaged channel estimation value and the second half averaged channel estimation value. Demodulator in communication equipment.
(Supplementary Note 3) The channel estimation value calculation means is provided for each path in a multipath environment, a path selection means for selecting a path having the highest power from each path, and a path selection path selected by the path selection means. Correlation value calculation for calculating a correlation value between the averaged channel estimation value in the first half and the averaged channel estimation value in the second half for each of the plurality of channel estimation values calculated by the channel estimation value calculation means. Means, and a channel estimation value selecting means for comparing the correlation values calculated by the correlation value calculating means with each other and selecting a channel estimation value having the highest correlation value. A channel estimation value having the same averaging time as a channel estimation value selected in a path with high power is selected from a plurality of channel estimation values in other paths. Demodulator in a mobile communication device according to Appendix 1.
(Supplementary Note 4) The channel estimation value calculating means is provided for each path in a multipath environment, and for each of a plurality of channel estimation values calculated by the channel estimation value calculating means, the first half channel estimation values from all paths. Value calculating means for calculating a correlation value between the correlation value and the channel estimation value in the second half, and each correlation value calculated by the correlation value calculating means is compared with each other, and the channel estimation value for the averaging time having the highest correlation value is obtained. The mobile communication device according to claim 1, further comprising: comparison means for instructing channel estimation, and channel estimation value selection means for each path for selecting a channel estimation value of the averaging time instructed by the comparison means. Demodulator.
(Supplementary Note 5) Channel estimation value calculation means for calculating a plurality of channel estimation values having different averaging times respectively for a plurality of channel estimation value samples having different timings, and an averaging time calculated by the channel estimation value calculation means. Correlation value calculation means for calculating a correlation value between the first half and the second half from all channel estimation value samples having different timings for each of a plurality of different channel estimation values, and each correlation value calculated by the correlation value calculation means A comparison means for comparing each other with each other and indicating a channel estimation value of the averaging time having the highest correlation value; and a channel estimation value selection means for selecting a channel estimation value of the averaging time indicated by the comparison means. 5. The demodulator in the mobile communication device according to any one of supplementary notes 1 to 4, wherein:
(Supplementary Note 6) The channel estimation value calculation means is provided for each path in a multipath environment, and the first half of each of the plurality of channel estimation values calculated by the channel estimation value calculation means is independently calculated for each path. Correlation value calculating means for calculating a correlation value between the averaged channel estimation value of the section and the averaged channel estimation value of the second half, and comparing the correlation values calculated by the correlation value calculation means with each other, 3. The demodulator in the mobile communication device according to claim 1, further comprising: a channel estimation value selecting unit that selects a channel estimation value having a high channel estimation value.
[0057]
【The invention's effect】
As described above, according to the present invention, for a symbol to be demodulated, a plurality of channel estimation values having different averaging times (reference symbol extraction sections) are calculated, and an average is calculated for each of the plurality of channel estimation values. Calculates the correlation value between the averaged channel estimation value of the first half and the averaged channel estimation value of the second half within the quantization time, and uses the channel estimation value with the highest correlation value to superimpose noise on the wireless transmission path. In addition, a highly accurate channel estimation value can be obtained for random phase fluctuations, and demodulation using the channel estimation value can improve the accuracy of a demodulated signal.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration of a demodulator according to the present invention.
FIG. 2 is a diagram illustrating an embodiment in which channel estimation values having different numbers of reference symbols are prepared.
FIG. 3 is a diagram illustrating an embodiment using a channel estimation value obtained by weighting each reference symbol.
FIG. 4 is a diagram showing an embodiment in which channel estimation values are independently selected for each path in a multipath environment.
FIG. 5 is a diagram illustrating an example in which a channel estimation value is selected using a path having the highest power.
FIG. 6 is a diagram illustrating an example in which a channel estimation value is selected based on a correlation value of the channel estimation value calculated for each path.
FIG. 7 is a diagram illustrating an example of selecting a channel estimation value based on a correlation value of a plurality of channel estimation value samples.
FIG. 8 is a diagram showing a block configuration of a mobile communication device to which the demodulator of the present invention is applied.
FIG. 9 is a diagram illustrating a configuration of a conventional demodulation unit.
FIG. 10 is a diagram illustrating a configuration of a conventional demodulation unit having a speed detection function.
[Explanation of symbols]
1-1 (# 1, # 2, #n) Channel estimation calculation section
1-10 Channel estimation unit
1-11 First half of channel estimation
1-12 Second half of channel estimation
1-13 Correlation Calculation Unit
1-2 Selector
1-3 Comparison section
9-1 Individual channel despreading unit
9-2 Despreading part of common pilot channel
9-4 Multiplier

Claims (5)

In a demodulator that performs channel estimation using a known signal time-multiplexed to a common channel or an individual channel and performs synchronous detection using the channel estimation value,
Channel estimation value calculating means for calculating a plurality of channel estimation values having different averaging times for symbols to be demodulated;
For each of the plurality of channel estimation values, a reference symbol within the averaging time is divided into a first half and a second half, and a correlation value between the averaged channel estimation value of the first half and the averaged channel estimation value of the second half is calculated. Correlation value calculating means,
Channel estimation value selection means for comparing each correlation value calculated by the correlation value calculation means with each other and selecting a channel estimation value having the highest correlation value,
Means for applying a phase rotation for channel compensation to a received symbol and demodulating the received symbol by using the channel estimation value selected by the channel estimation value selecting means. The channel estimation value calculation means prepares different numbers of reference symbols as a plurality of channel estimation values, weights each reference symbol in the time axis direction,
The correlation value calculating means has a configuration for calculating a correlation value between the averaged channel estimation value of the first half and the averaged channel estimation value of the second half for each of the weighted reference symbols. The demodulator in the mobile communication device according to claim 1. Comprising the channel estimation value calculation means for each path in a multipath environment,
Path selection means for selecting the path with the highest power from each path;
For each of the plurality of channel estimation values calculated by the channel estimation value calculating means of the path selected by the path selecting means, the first half averaged channel estimation value and the second half averaged channel estimation value are calculated for each channel estimation value. Correlation value calculation means for calculating a correlation value with
Comparing the correlation values calculated by the correlation value calculation means with each other, and selecting a channel estimation value having the highest correlation value,
The channel estimation value selecting means has a configuration in which a channel estimation value having the same averaging time as a channel estimation value selected in a path having the highest power is selected from a plurality of channel estimation values in other paths. The demodulator in the mobile communication device according to claim 1. Comprising the channel estimation value calculation means for each path in a multipath environment,
Correlation value calculation means for calculating a correlation value between the first half channel estimation value and the second half channel estimation value from all paths for each of the plurality of channel estimation values calculated by the channel estimation value calculation means,
A comparison unit that compares the correlation values calculated by the correlation value calculation unit with each other and indicates a channel estimation value of an averaging time having the highest correlation value;
2. The demodulator according to claim 1, further comprising: a channel estimation value selecting unit for each path for selecting a channel estimation value of the averaging time specified by the comparing unit. Channel estimation value calculating means for calculating a plurality of channel estimation values having different averaging times for a plurality of channel estimation value samples having different timings,
For each of a plurality of channel estimation values having different averaging times calculated by the channel estimation value calculation means, a correlation value calculation means for calculating a correlation value between the first half and the second half from all the channel estimation value samples having different timings. ,
A comparison unit that compares the correlation values calculated by the correlation value calculation unit with each other and indicates a channel estimation value of an averaging time having the highest correlation value;
5. The demodulator in a mobile communication device according to claim 1, further comprising: a channel estimation value selection unit that selects a channel estimation value of the averaging time specified by the comparison unit.

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