JP4066021B2 - Demodulator in mobile communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a demodulator in a mobile communication device, which transmits a known signal to a common channel or a part of an individual channel, performs channel estimation based on the received known signal, and performs synchronous detection using the estimated value as a reference phase. It relates to a demodulator that performs.
[0002]
3GPP (3^rd In the specifications of the Generation Partnership Project), a DS CDMA (direct sequence code division multiple access) transmission system capable of separating user signals, reducing interference between base stations, and multipath separation is adopted, and the phase of an individual channel is adopted. In this system, a common pilot channel (CPICH) is transmitted as a phase reference for demodulating the modulation signal.
[0003]
In a mobile communication environment, random phase fluctuations frequently occur due to fading, and in the phase modulation method, it is difficult to generate a demodulation reference phase by carrier recovery. Therefore, in the CDMA transmission system, a means for demodulating the data signal using the phase as a reference phase is transmitted by code-multiplexing or time-multiplexing a signal having a known phase together with the data signal.
[0004]
FIG. 8 shows a block configuration of a mobile communication apparatus 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-digital converter, 8-5 is a searcher for detecting a path, and 8-6 is a demodulator of a received signal. A demodulator for decoding the demodulated received signal, an encoding / decoding unit for encoding the transmission signal, a control unit for 8-8, and a modulated transmission signal for 8-9 8-10 is a digital-analog converter, and 8-11 is a power amplifier. The present invention particularly relates to the configuration of the demodulator 8-6 shown in FIG.
[Prior art]
[0005]
FIG. 9 shows the configuration of a conventional demodulator. The despreading unit 9-1 in the figure despreads the dedicated channel at the path timing notified from the searcher. The despreading section 9-2 despreads the common pilot channel at the same timing, and the channel estimation section 9-3 averages the despread signal of the common pilot channel, so that the signal near the symbol of the individual channel to be demodulated Detect the reference phase. The multiplier 9-4 rotates the phase of the individual channel using the channel estimation value as a reference phase and detects the channel.
[0006]
The detection result is output as a demodulated signal through a RAKE combining unit 9-5 that combines multipath received signals to increase the gain. Note that a plurality of dedicated channel despreading sections 9-1, common pilot channel despreading sections 9-2, channel estimation sections 9-3, and multipliers 9-4 are provided for each multipath path. .
[0007]
In mobile communication, noise is added on the radio transmission path and the 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 over a long period of time, random phase fluctuations cannot be ignored. Accordingly, the averaging time for noise removal and the accuracy of phase detection are in a trade-off relationship.
[0008]
The phase fluctuation occurs at a frequency proportional to the moving speed of the moving body. Therefore, there is a technique for measuring the speed of a mobile unit and determining the average number of symbols of a common pilot channel according to the moving speed. FIG. 10 shows a configuration in which a speed detection function is provided in the demodulation unit. In the figure, the speed detector 10-1 detects the speed of the moving body, and gives the speed information to the channel estimator 9-3. Channel estimation section 9-3 determines the average number of symbols for the common pilot channel according to the speed information, and calculates a channel estimation value.
[0009]
  The following documents are listed as prior art documents related to the present invention. The following patent documents1Describes a technique in which an accurate channel estimation value is obtained by taking a correlation with a known symbol pattern and selecting a signal with a symbol pattern having the highest correlation.PatentDocument 2 describes an invention related to multipath path selection of a CDMA receiver.
[0010]
  Patent Document 3 describes a technique for calculating a channel estimation value (carrier phase) using past data, and a technique for selecting an individual channel and a common pilot based on a certain standard. Patent Document 4 discloses path timing detection for detecting a multipath.InRelated technologies are described. Patent Document 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 Document 6 describes a technique for dynamically changing channel estimation weights based on level measurement values and the number of level crossings. Patent Document 7 describes a technique that uses a plurality of pilot symbols for channel estimation, weights them, and increases the accuracy of the channel estimation value. Patent Document 8 describes a technique for improving the accuracy of a channel estimation value by using a pilot symbol portion of a broadcast signal that would have a large transmission power. Patent Document 9 describes a technique in which a plurality of reference phases are prepared, the reference phase is compared with the phase of the received signal, and the selection of the reference phase is updated.
[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 2002-94584 A
[Patent Document 5]
Japanese Patent Laid-Open No. 10-190494
[Patent Document 6]
JP 2001-267960 A
[Patent Document 7]
Japanese Patent Laid-Open No. 10-51424
[Patent Document 8]
JP 2000-252960 A
[Patent Document 9]
Japanese Patent Laid-Open No. 7-273712
[0013]
[Problems to be solved by the invention]
When determining the average number of symbols of the common pilot channel according to the moving speed described above, several speed detections such as estimating the Doppler frequency from the fluctuation of the amplitude of the received signal and the phase of the demodulated signal and detecting the moving speed However, each method requires a 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 it to the intermittent reception standby operation of a mobile communication terminal, which is an essential requirement for low power consumption. . In addition, when determining the number of averaged symbols based on the moving speed, the signal quality that changes according to the strength of the received signal is not taken into account, so that, for example, sufficient when the mobile station is stationary just below the base station. Despite the fact that good signal quality is obtained with a strong received signal, there is a possibility that wasteful power may be consumed by selecting and calculating the number of unnecessary average symbols. .
[0015]
The present invention improves the accuracy of a demodulated signal by calculating a channel estimation value of the optimal number of averaged symbols by simple arithmetic processing, obtaining a highly accurate channel estimation value, and demodulating using the channel estimation value The purpose is to let you.
[0016]
[Means for Solving the Problems]
The demodulator in the mobile communication apparatus of the present invention is (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 reference symbols within the averaging time for each of the plurality of channel estimation values, The correlation value calculation means for calculating the correlation value between the average channel estimation value in the first half and the average channel estimation value in the second half and the correlation values calculated by the correlation value calculation means are compared with each other. Channel estimation value selection means for selecting the channel estimation value with the highest correlation value, and the channel estimation value selected by the channel estimation value selection means, and for channel compensation. 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 The correlation value between the average channel estimation value in the first half and the average channel estimation value in the second half is calculated for each weighted reference symbol.
[0018]
Also, (3) the channel estimation value calculating means corresponding to each path in a multipath environment, a path selecting means for selecting the path with the highest power among the paths, and a path selected by the path selecting means Correlation value for calculating the correlation value between the average channel estimation value in the first half and the average channel estimation value in the second half for each channel estimation value for a plurality of channel estimation values calculated by the channel estimation value calculation means Comparing each correlation value calculated by the correlation value calculation unit with each other, and selecting a channel estimation value selection unit that selects a channel estimation value having the highest correlation value, the channel estimation value selection unit includes: The channel estimation value selected in the path with the highest power and the channel estimation value having the same averaging time are 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 the plurality of channel estimation values calculated by the channel estimation value calculation means, the first half of the channel estimation from all paths A correlation value calculating means for calculating a correlation value between the value and the channel estimation value of the latter half part, and comparing each correlation value calculated by the correlation value calculating means with each other, and channel estimation of the averaging time with the highest correlation value Comparing means for instructing a value, and channel estimation value selecting means for each path for selecting the channel estimation value of the averaging time instructed by the comparing means.
[0020]
Further, the accuracy can be further improved by detecting a statistical propagation path property. The demodulator in the mobile communication apparatus of the present invention, which is selected based on the result of integrating the correlation values of a plurality of timings separated in time, (5) averaging time for each of a plurality of channel estimation value samples having different timings. Channel estimation value calculating means for calculating a plurality of channel estimation values of different channel times, and for each of a plurality of channel estimation values having different averaging times calculated by the channel estimation value calculation means, from all channel estimation value samples having different timings. Correlation value calculation means for calculating a correlation value between the first half and the second half and each correlation value calculated by the correlation value calculation means are compared with each other, and the channel estimation value of the averaging time with the highest correlation value is indicated. And a channel estimation value selection means for selecting a channel estimation value for the averaging time designated by the comparison means.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the basic configuration of the demodulator of the present invention. The despreading unit 9-1 despreads the dedicated 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 (n) of channel estimation values with different numbers of reference symbols in the averaging process. Are provided, 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 channel estimation calculation unit 1-1 (# 1, # 2,..., #N), each channel estimation unit 1-10 uses a predetermined reference symbol based on the despread signal of the known signal of the common pilot channel. In addition to calculating a channel estimation value that has been averaged by a number, the first half of channel estimation 1-11 calculates a channel estimation value from reference symbols in the first half of a predetermined number of reference symbols, and the second half of channel estimation 1- 12, the channel estimation value is calculated from the reference symbols in the latter half of the predetermined number of reference symbols.
[0023]
Channel estimation values from channel estimation first half 1-11 and channel estimation second half 1-12 are input to correlation calculation section 1-13, and correlation calculation section 1-13 performs channel estimation from channel estimation first half 1-11. The correlation between the value and the channel estimation value from the channel estimation second half 1-12 is calculated, and the value is output to the comparison unit 1-3.
[0024]
The comparison unit 1-3 compares the correlation values of the first half of the channel estimation and the second half of the channel estimation input from each channel estimation calculation unit 1-1 (# 1, # 2,..., #N). The channel estimation calculation unit 1-1 (any one of # 1, # 2,..., #N) having the highest correlation value is selected, and the channel estimation calculation unit 1-1 (# 1, # 2) is selected. ,..., #N) and outputs a command signal to the selection unit 1-2.
[0025]
The selection unit 1-2 includes a channel estimation calculation unit 1-1 (any one of # 1, # 2,..., #N) instructed by the comparison unit 1-3 from the channel estimation unit 1-10. The output channel estimation value is selected, and the channel estimation value is output to the multiplier 9-4. Using this channel estimation value as a reference phase, the multiplier 9-4 performs phase detection on the individual channel to obtain a demodulated signal.
[0026]
In this way, a plurality (n) of channel estimation values with different channel estimation reference symbol extraction intervals (average time) are calculated, and the channel estimation values are divided into a first half and a second half, and the first half and the second half. By calculating the correlation value with the unit and selecting the channel estimation value with the highest correlation value, the channel estimation value with the highest quality is used for demodulation as the reference phase, 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 latter half becomes higher as the averaging time is shorter, and when there is much noise, the correlation between the first half and the second half becomes higher as the averaging time is longer. If both influences are present, the correlation value including the respective elements is the upper correlation value, but the channel estimation value with the highest correlation value in the first half and the second half can be regarded as the most accurate and the most correlated. A channel estimation value having 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 in which the average number of common pilot symbols is used as a parameter. Compared to the weighting method, it can be realized with a simple configuration.
[0029]
An example of the correlation calculation process is shown below. The first half average value of the channel estimation values of the first averaged reference symbol number (I_a1, Q_a1), The latter half average value (I_b1, Q_b1), The first half average value of the channel estimation values of the second averaged reference symbol number (I_a2, Q_a2), The latter half average value (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 as shown in 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]
Further, 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 as shown in 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 a square root (√). The same applies to the following equations.
[0032]
FIG. 3 shows an embodiment using a plurality of channel estimation values in which the number of averaged reference symbols is different and each reference symbol is weighted differently in the time axis direction. Since a reference symbol closer in time to a symbol to be demodulated (symbol to be demodulated) has a higher phase correlation, a reference symbol closer to the center has a higher weight to obtain a highly accurate channel estimation value. Can do.
[0033]
However, since the optimum value of the weighting coefficient changes due to changes in the moving speed and noise power, it is also effective to prepare several weighting coefficient models and calculate the optimum value in advance. The weighting coefficient is basically a scalar, but the effectiveness of vectorization cannot be denied.
[0034]
An example of correlation calculation processing in the second embodiment is shown below. The first half average value after weighting the channel estimation value of the first averaged reference symbol number is (I ′_a1, Q ’_a1), And the latter half average value (I ’_b1, Q ’_b1), The first half average value of the channel estimation value of the second averaged reference symbol number (I ′_a2, Q ’_a2), And the latter half average value (I ’_b2, Q ’_b2), The correlation value Rw between the first half and the second half of the channel estimation value of the first number of averaged reference symbols is as shown in 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]
Also, 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 as shown in 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 selected independently for each path under a multipath environment. Means for selecting the channel estimation value having the highest correlation value for each path is provided, and a channel estimation value is independently selected for each path, and demodulation of each path detected by the estimated value is performed. The signals are input to the RAKE combining unit 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 reference numerals as those in FIG.
[0038]
In the multipath environment shown in FIG. 5, the channel estimation value of the path with the highest power is selected from the received signals of the multipath, and the channel estimation value having the highest correlation between the first half and the second half is selected. An embodiment 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 other paths will be described.
[0039]
In FIG. 5, a plurality of channel estimation values having different averaging times (reference symbol numbers) 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, and the power comparison / maximum selection unit 5-1 has the strongest power among them. And the channel estimation value having the highest correlation value between the first half and the second half is selected from the plurality of channel estimation values for the path by the selection unit 5-2.
[0040]
An instruction signal for instructing to select a channel estimation value having the same averaging time (number of reference symbols) as the channel estimation value selected by the selection unit 5-2 for other paths is also selected by the selection unit 1 of each other path. -2 is selected, and the selection unit 1-2 of each path selects a channel estimation value according to the instruction signal.
[0041]
In a multipath environment, an average time (number of reference symbols) is determined using the channel estimation value for the strongest power path that most affects the quality after RAKE combining. Although it is expected that the performance is slightly degraded by following the determination of the strong path, the calculation processing amount can be greatly reduced because the correlation value calculation process is performed only for one path.
[0042]
In FIG. 6, in a multipath environment, a plurality of channel estimation values calculated for each path are correlated with the first half and the second half over all paths for each channel estimation value of the same averaging time (number of reference symbols). An example is shown in which a value is calculated and a channel estimation value of the averaging time (number of reference symbols) having the highest correlation value is selected.
[0043]
In FIG. 6, a channel estimation calculation unit 1-1 (# 1, # 2) that calculates 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 (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, respectively.
[0044]
Correlation calculation units 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 values 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 averaging time (number of reference symbols) having the highest correlation value is selected. In addition, an instruction signal is sent to the selection unit 1-2 of each path.
[0045]
An example of correlation processing in the correlation calculation units 6-1 and 6-2 corresponding to a plurality of channel estimation values is shown below. For the first pass, the first half average value of the channel estimation values of the first averaging time (number of reference symbols) is (I_p1a1, Q_p1a1), The latter half average value (I_p1b1, Q_p1b1), The first half average value of the channel estimation value of the second averaging time (number of reference symbols) (I_p1a2, Qp1a2), the latter half average value is (I_p1b2, Q_p1b2).
[0046]
For the second path, the first half average value of the channel estimation values of the first averaging time (number of reference symbols) is (I_p2a1, Q_p2a1), The latter half average value (I_p2b1, Q_p2b1), The first half average value of the channel estimation value of the second averaging time (number of reference symbols) (I_p2a2, Q_p2a2), The latter half average value (I_p2b2, Q_p2b2).
[0047]
The correlation value Rp (# 1) between the first half and the second half of the first averaging time (number of reference symbols) is expressed 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 (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 interval (average time) for channel estimation is selected for each path using correlation values of a plurality of channel estimation value samples having different timings. Since each channel estimation calculation unit 1-1 (# 1, # 2) holds a plurality of channel estimation value samples having different timings, the correlation value between the first half average value and the second half average value of the channel estimation value at each timing is obtained. A memory / averaging unit 7-2 for once storing is provided.
[0050]
The correlation value obtained by averaging each timing is input to the comparison unit 1-3. The comparison unit 1-3 compares the correlation values input from the respective channel estimation calculation units 1-1 (# 1, # 2), and selects the channel estimation value having the highest correlation value among them. An instruction signal is output to 1-2. The selection unit 1-2 selects a channel estimation value according to the instruction signal.
[0051]
An example of correlation calculation processing in the correlation calculation unit 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 (number of reference symbols) is (I_a1t1, Q_a1t1), The latter half average value (I_b1t1, Q_b1t1), The first half average value after weighting the channel estimation value of the second averaging time (number of reference symbols) (I_a2t1, Q_a2t1), The latter half average value (I_b2t1, Q_b2t1).
[0052]
For the channel estimation value at the second sample timing t2, the first half average value after weighting of the channel estimation value of the first averaging time (number of reference symbols) is (I_a1t2, Q_a1t2), The latter half average value (I_b1t2, Q_b1t2), The first half average value after weighting the channel estimation value of the second averaging time (number of reference symbols) (I_a2t2, Q_a2t2), The latter half average value (I_b2t2, Q_b2t2).
[0053]
A correlation value Rt (# 1) between the first half and the second half of the channel estimation value of the first averaging time (number of reference symbols) is expressed 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 (number of reference symbols) is as follows, with a1 in the above equation replaced with a2 and b1 replaced 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 the channel estimation value selection means of each embodiment can be appropriately combined, and various modifications can be made without departing from the spirit of the present invention.
[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 calculation means for calculating a plurality of channel estimation values different from each other, and for each of the plurality of channel estimation values, a reference symbol within an averaging time is divided into a first half and a second half, and the average channel of the first half Correlation value calculating means for calculating a correlation value between the estimated value and the average channel estimation value of the latter half and each correlation value calculated by the correlation value calculating means are compared with each other, and the channel estimation value having the highest correlation value A channel estimation value selecting means for selecting the channel estimation value and a channel estimation value selected by the channel estimation value selecting means, and applying a phase rotation for channel compensation to the received symbol for demodulation 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 appendix 1, wherein a correlation value between the average channel estimation value of the first half and the average channel estimation value of the second half is calculated for each weighted reference symbol A demodulator in a communication device.
(Supplementary Note 3) The channel estimation value calculation means is provided for each path in a multipath environment, and the path selection means for selecting the path with the highest power among the paths, and the path selected by the path selection means Correlation value calculation for calculating a correlation value between the average channel estimation value in the first half and the average channel estimation value in the second half for each channel estimation value for a plurality of channel estimation values calculated by the channel estimation value calculation means And a channel estimation value selection unit that compares the correlation values calculated by the correlation value calculation unit with each other and selects a channel estimation value with the highest correlation value. A channel estimation value selected in a path with high power and a channel estimation value having the same averaging time are 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 calculation means is provided for each path in a multipath environment, and the first half of the channel estimation values from all the paths is calculated for each of the plurality of channel estimation values calculated by the channel estimation value calculation means. Correlation value calculating means for calculating a correlation value between the channel estimation value and the latter half channel estimation value, and comparing each correlation value calculated by the correlation value calculation means with each other, and the channel estimation value of the averaging time with the highest correlation value The mobile communication apparatus according to claim 1, further comprising: comparing means for instructing channel estimation; and channel estimation value selection means for each path for selecting the channel estimation value for the averaging time indicated 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 for a plurality of channel estimation value samples having different timings, and the averaging time calculated by the channel estimation value calculation means Correlation value calculation means for calculating correlation values 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 Comparing means for comparing each other and indicating the channel estimation value of the averaging time having the highest correlation value, and channel estimation value selecting means for selecting the channel estimation value of the averaging time indicated by the comparing means 5. A demodulator in a mobile communication device according to any one of appendices 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 channel estimation value for each of the channel estimation values calculated by the channel estimation value calculation means independently of each path. A correlation value calculation means for calculating a correlation value between the average channel estimation value of the first part and the average channel estimation value of the second half part, and the correlation values calculated by the correlation value calculation means are compared with each other. The demodulator in the mobile communication apparatus according to appendix 1, characterized in that the demodulator comprises a channel estimation value selection means for selecting a high channel estimation value.
[0057]
【The invention's effect】
As described above, according to the present invention, a plurality of channel estimation values having different averaging times (reference symbol extraction intervals) are calculated for the demodulation target symbols, and the average is calculated for each of the plurality of channel estimation values. By calculating the correlation value between the average channel estimation value of the first half and the average channel estimation value of the second half within the conversion time, and using the channel estimation value with the highest correlation value, noise superimposition on the wireless transmission path In addition, it is possible to obtain a highly accurate channel estimation value with respect to random phase fluctuations, and it is possible to improve the accuracy of the demodulated signal by performing demodulation using the channel estimation value.
[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 channel estimation values in which each reference symbol is weighted.
FIG. 4 is a diagram illustrating an embodiment in which a channel estimation value is selected independently for each path under a multipath environment.
FIG. 5 is a diagram illustrating an embodiment in which a channel estimation value is selected using a path with the highest power.
FIG. 6 is a diagram illustrating an embodiment in which a channel estimation value is selected based on a correlation value of channel estimation values calculated in each path.
FIG. 7 is a diagram showing an embodiment in which channel estimation values are selected based on correlation values 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 demodulator.
FIG. 10 is a diagram illustrating a configuration of a conventional demodulator having a speed detection function.
[Explanation of symbols]
1-1 (# 1, # 2, #n) Channel estimation calculation unit
1-10 Channel estimation unit
1-11 First half of channel estimation
1-12 Second half of channel estimation
1-13 Correlation calculator
1-2 Selector
1-3 Comparison unit
9-1 Despreading section of dedicated channel
9-2 Despreading part of common pilot channel
9-4 Multiplier

Claims (2)

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,
Channel estimation value calculation means for calculating a plurality of channel estimation values having different averaging times for the symbols to be demodulated for each path in a multipath environment ;
Path selection means for selecting the path with the highest power among the paths;
For the plurality of channel estimation values calculated by the channel estimation value calculation unit of the path selected by the path selection unit, the reference symbols within the averaging time for each of the plurality of channel estimation values, A correlation value calculating means for calculating a correlation value between the average channel estimation value of the first half and the average channel estimation value of the second half;
Channel correlation value selection means for comparing each correlation value calculated by the correlation value calculation means with each other and selecting the channel estimation value with the highest correlation value ,
The channel estimation value selection means has a configuration for selecting a channel estimation value having the same averaging time as a channel estimation value selected in a path with the highest power from a plurality of channel estimation values in other paths,
A demodulator in a mobile communication device, comprising: means for demodulating a received symbol with a phase rotation for channel compensation using the channel estimation value selected by the channel estimation value selection means. 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,
Channel estimation value calculation means for calculating a plurality of channel estimation values having different averaging times for the symbols to be demodulated for each path in a multipath environment;
Correlation value calculating means for calculating a correlation value between the channel estimation value of the first half part and the channel estimation value of the second half part from all paths for each of the plurality of channel estimation values calculated by the channel estimation value calculation means;
Comparing means for comparing the correlation values calculated by the correlation value calculating means with each other, and indicating the channel estimation value of the averaging time with the highest correlation value;
Channel estimation value selection means for each path for selecting the channel estimation value of the averaging time indicated by the comparison means;
Means for using the channel estimation value selected by the channel estimation value selection means and applying a phase rotation for channel compensation to the received symbol for demodulation;
A demodulator in a mobile communication device comprising:

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