JP2002261852A - Synchronization detecting circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronization detecting circuit in which optimal synchronization detection can be effected easily depending on the moving speed of a mobile station. SOLUTION: A vehicle speed detecting section 108 estimates the moving speed by performing delay detection of phase variation based on the pilot symbol of a receiving base band signal, and based on the estimated moving speed, any one of a first phase compensation vector calculated at an averaging section 106 or a second phase compensation vector calculated at a primary interpolating section 107 is selected and subjected to complex conjugate multiplication by a corresponding information symbol thus performing synchronization detection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous detection circuit using pilot symbols in mobile communication, and more particularly to a synchronous detection circuit capable of easily performing optimum synchronous detection according to the moving speed of a mobile station. .

[0002]

2. Description of the Related Art In mobile communication such as a portable telephone, demodulation of a modulated signal is performed by comparing a modulated signal transmitted after being modulated with a signal having a reference phase for phase detection. Will be Here, extraction of a signal having a phase synchronized with the modulation signal from the modulation signal, that is, carrier wave reproduction is performed,
A method of demodulating this signal as a reference phase signal is synchronous detection.

[0003] In mobile communication, the radio propagation path fluctuates as the mobile station moves, and the phase of a modulated signal transmitted by radio is fluctuated. FIG. 5 is a conceptual diagram of a mobile communication system. The mobile station 52 performs two-way communication of wireless signals via the base station 51. If the phase change of the modulated signal transmitted from the mobile station 52 or the base station 51 occurs with the movement of the mobile station 52, the carrier recovery cannot follow the phase change, so that the base station 5 that receives the modulated signal
In each of the mobile station 1 and the mobile station 52, it is difficult to perform demodulation by synchronous detection.

For this reason, in a mobile communication receiver that demodulates a modulated signal by using synchronous detection, various synchronous detection circuits have been proposed that compensate for the generated phase fluctuation and obtain an optimal synchronous detection result. Has been put to practical use.

FIGS. 2 to 4 show a conventional synchronous detection circuit.
This will be described with reference to FIG. FIG. 2 is a configuration block diagram of a conventional synchronous detection circuit. The synchronous detection circuit in FIG. 2 estimates a radio channel variation using a pilot symbol in a complex-modulated received baseband signal, and compensates for a phase variation of the received baseband signal using an estimated value of the radio channel variation. This is a synchronous detection circuit.

The configuration of a received baseband signal to be subjected to synchronous detection will be described with reference to FIG. FIG. 3 is a diagram showing a frame format of a received baseband signal. A plurality of slots are continuously arranged in a frame of the received baseband signal, and each slot includes a pilot symbol block and an information symbol block. The pilot symbol block has a configuration in which a plurality of pilot symbols are arranged, and the information symbol block has a configuration in which a plurality of information symbols are arranged. The received baseband signal has both in-phase and quadrature components as shown in FIG.
The configuration is made.

The digitally converted in-phase and quadrature-component received baseband signals are separated into pilot symbol blocks and information symbol blocks by signal separation means (not shown) in the synchronous detection circuit of FIG. Output to channel estimation section 202.
In the memory 201, an information symbol block is input and stored for each slot.

The channel estimation section 202 receives a pilot symbol block for each slot and performs complex conjugate multiplication with the pilot symbol replica generated by the pilot symbol replica generation section 203 to calculate the amount of phase variation. Further, channel estimation section 202 averages the phase fluctuation amounts of all pilot symbols in one pilot symbol block to calculate the average phase fluctuation amount.

In the receiver including the synchronous detection circuit shown in FIG. 2, the pilot symbol pattern transmitted from the transmitter is recognized in advance, and the pilot symbol replica generation unit 2
In 03, when the pilot symbol is received by the channel estimation section 202, a pilot symbol replica having the same phase as when the pilot symbol was generated by the transmitter is generated and output to the channel estimation section 202.

Here, assuming that the vector of the k-th pilot symbol in one pilot symbol block is (P _ik + jP _qk ) and the vector of the k-th pilot symbol replica is (U _ik + jU _qk ), the average phase variation vector (R _i + jR _q ) is represented by the following equation.

[0011]

(Equation 1)

In equations (1) and (2), N is the number of pilot symbols in the pilot symbol block.

The average phase variation calculated by the channel estimator 202 is output to the first register 204 for each slot,
It is memorized. At the same time, the average phase fluctuation amount stored in the first register 204 is shifted to the second register 205 and stored. Hereinafter, the average phase variation stored in the first register is referred to as the latest average phase variation, and the average phase variation stored in the second register is referred to as the quasi-latest average phase variation. The correspondence between the latest and quasi-latest average phase fluctuation amounts and pilot symbol blocks is as shown in FIG. That is, the synchronous detection circuit in FIG. 2 can store the average phase fluctuation amount for the pilot symbol blocks of two consecutive slots.

In the synchronous detection circuit shown in FIG.
Reference numeral 06 simply averages the respective average phase variation vectors stored in the first register 204 and the second register 205 to calculate a phase compensation vector. Here, the latest average phase change amount is (R _i — _new + R _{q — new} ), and the quasi-latest average phase change amount is (R _i — _old +
_{Rq_old} ), the phase compensation vector (S _i + j)
S _q ) is represented by the following equation.

[0015]

(Equation 2)

The phase compensation vector calculated by averaging section 206 is output to complex multiplier 207. Complex multiplier 2
In 07, the information symbols in the information symbol block corresponding to the phase compensation vector stored in the memory 201 are output, and the complex detection is completed by performing complex conjugate multiplication for each information symbol.

Here, the vector of the l-th information symbol in one information symbol block is represented by (I _il + jI
_ql ), the vector (E _il + jE _ql ) of the l-th information symbol after synchronous detection is represented by the following equation.

[0018]

(Equation 3)

The synchronous detection circuit shown in FIG. 2 performs synchronous detection on all information symbols in a slot. The obtained synchronous detection result is used for demodulation of a received baseband signal such as RAKE combining.

In the synchronous detection circuit of FIG. 2, a phase compensation vector is calculated by simply averaging the average phase variation of two consecutive pilot symbol blocks, and the phase compensation vector is used to compensate for the phase variation. Meanwhile, synchronous detection of information symbols is performed. Therefore, since the synchronous detection is performed using the same phase compensation vector for every information symbol in the information symbol block, the noise in the information symbol can be averaged.

FIG. 4 is a block diagram showing the configuration of another conventional synchronous detection circuit. The synchronous detection circuit of FIG. 3 is also a synchronous detection circuit for compensating for the phase variation of the received baseband signal based on the estimated value of the radio channel variation estimated using pilot symbols, as in FIG. Instead, a primary interpolation unit 301 is used, and the other configuration is the same as that of the synchronous detection circuit of FIG.

In the synchronous detection circuit shown in FIG. 4, the primary interpolation section 301 includes a vector of the latest average phase variation stored in the first register 204 and a quasi-latest average phase variation stored in the second register 205. A phase compensation vector is calculated by performing a linear interpolation on the vector of the quantity.

Here, the latest average phase fluctuation amount is represented by (R
_{i_new} + _{R q_new),} when the quasi-latest average phase variation amount and _{(R i_old +} R _{q_old),} a phase compensation vector _(S im + _{jS qm} for m-th information symbol in the information symbol block), the table by the following equation Is done.

[0024]

(Equation 4)

In equations (7) and (8), M is the number of information symbols in the information symbol block.

The primary interpolation unit 301 calculates a phase compensation vector for each information symbol based on the equations (7) and (8). The phase compensation vector is calculated by the complex multiplier 207 in the information symbol block corresponding to the phase compensation vector. Is performed for each information symbol, and the synchronous detection is completed.

In the synchronous detection circuit shown in FIG. 4, a phase compensation vector is calculated for each information symbol by continuously interpolating the phase variation of each of two consecutive pilot symbol blocks with a straight line. Synchronous detection of information symbols is performed while compensating for phase fluctuations using vectors. Therefore, the phase compensation vector changes the weight of the amount of phase variation by the information symbol,
For any of the information symbols in the information symbol block, the deviation of the phase compensation vector from the actual phase fluctuation amount can be reduced.

As another synchronous detection circuit,
Japanese Patent Application Laid-Open No. H11-220774 published on Aug. 10, 2001, entitled "Communication Control Device and Method Based on Moving Speed" (Applicant: Fujitsu Limited, Inventor: Tokuro Kubo et al.) A synchronous detection means for estimating a moving speed in an estimating means, controlling and multiplying a pilot symbol weighting factor for each pilot symbol based on the estimated moving speed, and using the sum of these as a phase estimate for synchronous detection is proposed. Have been.

[0029]

However, the above conventional synchronous detection circuit has a problem that it is not easy to perform synchronous detection according to the moving speed of the mobile station. In the synchronous detection method using the phase compensation vector calculated by simple averaging in the synchronous detection circuit of FIG. 2, in the information symbol near the center of the information symbol block, the deviation of the phase compensation vector with respect to the information symbol phase variation is small. In the vicinity of both ends of the information symbol block, the deviation of the phase compensation vector becomes large.

Therefore, as the mobile station moves at higher speed, the difference between the phase fluctuation amounts of the pilot symbols calculated in the two pilot symbol blocks becomes larger. Therefore, the shift of the phase compensation vector with respect to the actual phase fluctuation amount becomes larger as the position approaches the both ends of the information symbol block, and as a result, the probability of erroneously determining the information symbol in the demodulation process increases.

In the synchronous detection method using the phase compensation vector calculated by the primary interpolation in the synchronous detection circuit of FIG. 4, the information symbol at the center of the information symbol block has the phase calculated from the two pilot symbol blocks. The variation is averaged with the same weight. However, the weight of the phase fluctuation amount decreases as the position approaches the both ends of the information symbol block. In particular, the weight of one phase fluctuation amount becomes 0 in the information symbols at both ends, so that the noise averaging effect is reduced by half.

Therefore, when the mobile station is stopped or moving at a low speed, the more noisy the environment is,
The probability of erroneously determining the information symbols at both ends of the information symbol block during the demodulation process is higher than that of the synchronous detection circuit.

In the disclosed technique of Japanese Patent Application Laid-Open No. H11-220774, weighting of pilot symbols is controlled based on the estimated moving speed, so that it is necessary to set weighting parameters for each moving speed, which makes adjustment difficult. is there. Further, since a multiplier for multiplying the pilot symbol by the weight coefficient is required for the number of pilot symbols required for the phase estimation, there is a problem that the circuit scale is increased.

The present invention has been made in view of the above circumstances, and has as its object to provide a synchronous detection circuit that easily performs optimal synchronous detection according to the moving speed of a mobile station.

[0035]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides a synchronous detection circuit for compensating for a phase variation of an information symbol in a received baseband signal received by a mobile station. A phase variation is calculated by performing complex conjugate multiplication of a pilot symbol constituting a pilot symbol block included in a modulated received baseband signal and a pilot symbol replica, and averaging all phase variation in the pilot symbol block. To calculate the average amount of phase variation, perform delay detection for all the phase variation in the pilot symbol block,
The average instantaneous phase variation is calculated by averaging the delay detection results, the moving speed of the mobile station is estimated based on the average instantaneous phase variation, and the average phase variation in the relevant and immediately preceding pilot symbol block is simply averaged. Selecting one of the first phase compensation vector or the second phase compensation vector obtained by linearly interpolating the average phase variation in the current and previous pilot symbol blocks based on the moving speed;
Synchronous detection circuit that performs complex detection by performing complex conjugate multiplication of the selected phase compensation vector and the information symbol corresponding to the pilot symbol block, and facilitates optimal synchronous detection according to the moving speed of the mobile station. Can be.

[0036]

Embodiments of the present invention will be described with reference to the drawings. The synchronous detection circuit according to the embodiment of the present invention estimates the moving speed of the mobile station based on the delay detection result of the phase variation calculated from the pilot symbol and the pilot symbol replica in the received baseband signal, Selecting either the first phase compensation vector obtained by simply averaging the average phase fluctuation amount of the slot or the second phase compensation vector obtained by linearly interpolating the average phase fluctuation amount of the continuous slot based on the moving speed; By performing complex conjugate multiplication with the corresponding information symbol, the phase fluctuation of the information symbol is compensated for, so that optimum synchronous detection according to the moving speed of the mobile station can be easily performed.

The configuration of the synchronous detection circuit according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration block diagram of a synchronous detection circuit according to an embodiment of the present invention.
As in the prior art, the synchronous detection circuit of FIG. 1 also estimates radio channel fluctuations using pilot symbols in a complex-modulated received baseband signal, and uses the estimated values of the radio channel fluctuations to estimate the phase fluctuations of the received symbols. To compensate. In the synchronous detection circuit of the present invention, the configuration of the received baseband signal to be subjected to synchronous detection is the same as the frame format shown in FIG.

The synchronous detection circuit according to the embodiment of the present invention includes a memory 101, a channel estimation unit 120, a pilot symbol replica generation unit 103, a first register 1
04, a second register 105, an averaging unit 106, a primary interpolation unit 107, a vehicle speed detection unit 108, a selector 10
9 and a complex multiplier 110.

The memory 101 stores information symbol blocks included in the received baseband signal for each slot,
Output to the complex multiplier 110.

Channel estimating section 102 performs complex conjugate multiplication of a pilot symbol block included in the received baseband signal and a pilot symbol replica output from pilot symbol replica generating section 103 for each pilot symbol, and obtains the multiplication result. Calculate the phase fluctuation amount and output it to the vehicle speed detection unit 108

Further, channel estimation section 102 calculates an average phase variation by averaging the calculated phase variation by one symbol, and outputs the average phase variation to first register 104. The channel estimating section 102 calculates the average phase fluctuation amount using the above-described equations (1) and (2).

Pilot symbol replica generation section 103
When a pilot symbol is input to channel estimation section 102, a pilot symbol replica having the same phase as when the pilot symbol is generated at the transmitter is generated and output to channel estimation section 102.

The first register 104 stores the channel estimator 1
02, and stores the latest average phase variation output from the second register 105, the averaging unit 106, and the primary interpolation unit 1 at the same time.
07. The second register 105 stores the quasi-latest average phase fluctuation amount output from the first register 104. Further, the stored quasi-latest average phase fluctuation amount is output to the averaging unit 106 and the primary interpolation unit 107.

The averaging unit 106 calculates the latest average phase variation vector stored in the first register 104 and the second average phase variation vector.
A phase compensation vector is calculated by simply averaging the quasi-latest average phase variation vector stored in the register 105 and output to the selector 109. Averaging unit 106
Then, the phase compensation vector is calculated using the above-described equations (3) and (4).

The primary interpolation section 107 is provided with the first register 104
To calculate a phase compensation vector by performing a linear interpolation between the latest average phase variation vector stored in the second register 105 and the quasi-latest average phase variation vector stored in the second register 105, and outputs the vector to the selector 109. I do. The primary interpolation unit 107 calculates a phase compensation vector using the above-described equations (7) and (8).

The vehicle speed detecting section 108 includes the channel estimating section 10
2 to estimate the moving speed of the mobile station by delay detection of the amount of phase variation for each pilot symbol output from the pilot symbol 2, and based on the estimated speed, calculate the phase compensation vector output from the averaging unit 106 or the primary interpolation unit 107. One of them is selected, and a selector signal for outputting the selected phase compensation vector is output to the selector 109.

The selector 109 outputs one of the phase compensation vectors output from the averaging unit 106 or the primary interpolation unit 107 to the complex multiplier 110 based on the selector signal output from the vehicle speed detection unit 108. . The complex multiplier 110 performs a complex conjugate multiplication of the phase compensation vector output from the selector 109 and calculated by either the averaging unit 106 or the primary interpolation unit 107 and the information symbol output from the memory 101 as an information symbol. Every time,
Performs synchronous detection.

In the synchronous detection circuit shown in FIG.
1, a channel estimation unit 120, a pilot symbol replica generation unit 103, a first register 104, a second register 105, an averaging unit 106, and a primary interpolation unit 107
And the complex multiplier 110 have the same configuration as the corresponding elements in the conventional synchronous detection circuit.

Next, the operation of the synchronous detection circuit according to the embodiment of the present invention will be described with reference to FIG. The digitally converted in-phase and quadrature-component received baseband signals are separated into pilot symbol blocks and information symbol blocks by signal separation means (not shown) in the synchronous detection circuit of FIG. It is output to the unit 102. In the memory 101, an information symbol block is input and stored for each slot.

The channel estimation unit 102 receives a pilot symbol block for each slot, performs complex conjugate multiplication with the pilot symbol replica generated by the pilot symbol replica generation unit 103, and calculates the amount of phase variation for each pilot symbol. . Here, assuming that the vector of the k-th pilot symbol in the pilot symbol block is (P _ik + jP _qk ) and the vector of the k-th pilot symbol replica is (U _ik + jU _qk ), the phase variation vector (t _i + jt _q ) Is represented by the following equation.

[0051]

(Equation 5)

The calculated amount of phase fluctuation is transmitted to the vehicle speed detecting section 10.
8 is output. Further, channel estimation section 102 averages the amount of phase variation for all pilot symbols in one pilot symbol block using the above-described equations (1) and (2), and calculates the average amount of phase variation. , To the first register 104.

In the receiver including the synchronous detection circuit shown in FIG. 1, the pilot symbol pattern transmitted from the transmitter is recognized in advance, and the pilot symbol replica generator 1
In 03, when a pilot symbol is received by channel estimation section 102, a pilot symbol replica having the same phase as when the pilot symbol was generated by the transmitter is generated and output to channel estimation section 102.

The average phase variation calculated by the channel estimator 102 is output to the first register 104 and stored.
At the same time, the average phase fluctuation amount stored in the first register 104 is shifted to the second register 105 and stored. Further, the latest average phase change amount stored in the first register 104 and the quasi-latest average phase change amount stored in the second register 105 are respectively equalized by the averaging unit 1.
06 and the primary interpolation unit 107.

The averaging unit 106 simply averages the latest and quasi-latest average phase fluctuation vectors using the above equations (3) and (4), calculates a phase compensation vector, and outputs it to the selector 109. The primary interpolation unit 107 also calculates a phase compensation vector by performing primary interpolation on the latest and quasi-latest average phase variation vectors using the above-described equations (7) and (8). Output. Hereinafter, the phase compensation vector calculated by the averaging unit 106 is called a first phase compensation vector candidate, and the phase compensation vector calculated by the primary interpolation unit 107 is called a second phase compensation vector candidate.

On the other hand, vehicle speed detecting section 108 delay-detects the amount of phase variation for each pilot symbol output from channel estimating section 102 and estimates the moving speed of the mobile station.
Specifically, the vehicle speed detection unit 108 delay-detects the phase fluctuation amounts of successive pilot symbols to obtain the instantaneous phase fluctuation amount in one symbol section. Such an operation is repeated for all pilot symbols in the pilot symbol block, and finally all instantaneous phase fluctuations are averaged to calculate an average instantaneous phase fluctuation.

Here, when the vector of the average instantaneous phase variation is represented by a complex plane, when the mobile station is stopped, the vector of the average instantaneous phase variation shows almost 0 degrees with respect to the real axis.
As the moving speed of the mobile station increases, the angle with respect to the real axis increases. Using this phenomenon, the vehicle speed detector 1
08 indicates that the angle of the average instantaneous phase fluctuation amount with respect to the real axis (x-axis) is regarded as the moving speed of the mobile station. Furthermore, the vehicle speed detection unit 108 selects a first phase compensation vector candidate when the absolute value of the angle with respect to the real axis is less than a certain value, and selects a second phase compensation vector candidate when the absolute value of the angle is more than a certain value. , And outputs a select signal for outputting the selected phase compensation vector candidate to the selector 109.

The selector 109 selects one of the first and second phase compensation vectors based on the select signal output from the vehicle speed detector 108 and outputs the selected vector to the complex multiplier 110 as a phase compensation vector. I do.

The complex multiplier 110 outputs the phase compensation vector output from the selector 109 and the information symbols stored in the memory 101 in the information symbol block corresponding to the phase compensation vector. Complex multiplier 1
10 performs these complex conjugate multiplications for each information symbol using the above-described equations (5) and (6), and completes the synchronous detection. The obtained synchronous detection result is used for demodulation of a received baseband signal such as RAKE combining.

Regarding the criterion for selecting which phase compensation vector is selected, IEICE Technical Report RCS 96-72 (1996)
-08) A report has been made in "High-accuracy channel estimation method using multiple pilot blocks in DS-CDMA" (Hidehiro Ando, Mamoru Sawahashi: NTT Mobile Communication Network Co., Ltd.). According to the above document, assuming that the maximum Doppler frequency, which is a frequency variation value due to movement, is fd (Hz) and the insertion period of a pilot symbol block is Tp (symbol), an estimation method using a simple average is obtained when fd · Tp <0.1. However, it is shown that when fd · Tp> 0.1, the estimating method using primary interpolation can obtain good characteristics.

The synchronous detection circuit of the present invention can be applied regardless of the number of pilot symbols in a pilot symbol block.

As described above, according to the synchronous detection circuit of the embodiment of the present invention, the moving speed of the mobile station is estimated by delay-detecting the phase variation of the received baseband signal, and the estimated moving speed is determined. A vehicle speed detection unit 108 for selecting an optimal phase compensation vector according to the following equation is calculated, and the phase compensation vector is calculated by simple average or linear interpolation of the average phase variation of two consecutive pilot symbol blocks, By performing complex conjugate multiplication of any one of the phase compensation vector selected by the detection unit 108 and the information symbol, it is possible to perform optimal synchronous detection according to the moving speed of the mobile station, thereby improving the error rate characteristics. There is an effect that can be done.

In the synchronous detection circuit according to the embodiment of the present invention,
When the moving speed of the mobile station is lower than the specified value in the vehicle speed detecting unit 108, that is, when it is estimated that the moving speed is stopped or low, a phase compensation vector calculated by simply averaging the average phase fluctuation amount of continuous pilot symbol blocks is selected, By using for synchronous detection, the noise averaging effect is increased for all information symbols in the information symbol block.

Similarly, when the vehicle speed detector 108 estimates that the phase speed of the mobile station is equal to or higher than the specified value, that is, that the speed is high, the phase variation calculated by performing linear interpolation on the average phase variation of the continuous pilot symbol blocks. By selecting a compensation vector and using it for synchronous detection, the deviation between the actual amount of phase fluctuation and the phase compensation vector in all information symbols in the information symbol block is reduced. Therefore, the synchronous detection circuit according to the embodiment of the present invention can perform synchronous detection using a phase compensation vector corresponding to the moving speed of the mobile station.

Further, even when compared with the synchronous detection means in JP-A-11-220774, it is not necessary to adjust the weight coefficient of the pilot symbol for each moving speed, so that synchronous detection can be easily performed. Further, since the synchronous detection means does not require a multiplier used for phase estimation, the circuit scale occupied by the multiplier can be reduced.

Further, in the synchronous detecting means, the speed estimating means for estimating the moving speed is, for example, for estimating the moving speed using a transmission power control command or a desired wave power, and is independent of the synchronous detecting means. To estimate the moving speed. On the other hand, in the synchronous detection circuit according to the embodiment of the present invention, vehicle speed detection section 108 performs delay detection using the amount of phase variation of the pilot symbol, and estimates the moving speed based on the detection result.

That is, the vehicle speed detecting section 108 estimates the moving speed based on the difference between the phase fluctuations of the pilot symbols before and after using the phase fluctuations of the pilot symbols calculated in the process of calculating the phase compensation vector. Accordingly, it is possible to estimate the moving speed based on the actual amount of phase fluctuation, and it is possible to calculate a phase compensation vector that can sufficiently compensate for the phase fluctuation.

[0068]

According to the present invention, delay detection is performed on the amount of phase variation based on pilot symbols constituting a pilot symbol block included in a received baseband signal to estimate the moving speed of a mobile station. Based on the moving speed, either the first phase compensation vector obtained by simply averaging the current and previous average phase fluctuation amounts or the second phase compensation vector obtained by linearly interpolating the current and previous average phase fluctuation amounts is selected. Since the synchronous detection circuit performs the complex detection by performing complex conjugate multiplication of the selected phase compensation vector and the corresponding information symbol, there is an effect that the optimum synchronous detection according to the moving speed of the mobile station can be easily performed.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a synchronous detection circuit according to an embodiment of the present invention.

FIG. 2 is a configuration block diagram of a conventional synchronous detection circuit.

FIG. 3 is a diagram showing a frame format of a received baseband signal.

FIG. 4 is a configuration block diagram of another conventional synchronous detection circuit.

FIG. 5 is a conceptual diagram of a mobile communication system.

[Explanation of symbols]

101, 201: memory, 102, 202: channel estimator, 103, 203: pilot replica generator, 104, 204: first register, 105, 20
5: second register, 106, 206: averaging unit, 1
07, 301: primary interpolation unit, 108: vehicle speed detection unit,
109: selector, 110, 207: multiplier, 51
... Base station, 52 ... Mobile station

Claims (1)

[Claims] 1. A synchronous detection circuit for compensating for a phase variation of an information symbol in a received baseband signal received by a mobile station, comprising: a pilot symbol constituting a pilot symbol block included in the complex-modulated received baseband signal; Calculating a phase variation by performing complex conjugate multiplication with a pilot symbol replica; calculating an average phase variation by averaging all the phase variations in the pilot symbol block; and calculating an average phase variation in the pilot symbol block. Perform delay detection on the fluctuation amount, calculate the average instantaneous phase fluctuation amount by averaging the delay detection results, estimate the moving speed of the mobile station based on the average instantaneous phase fluctuation amount, and The first phase compensation base is obtained by averaging the average phase fluctuation amount in the symbol block. And the first phase compensation vector based on the moving speed based on the moving speed. Or selecting one of the second phase compensation vectors, performing complex conjugate multiplication of the selected phase compensation vector and an information symbol corresponding to the pilot symbol block to perform synchronous detection. Detection circuit.