JP5048104B2 - Automatic frequency controller - Google Patents

Description

  The present invention relates to an automatic frequency control device used in a mobile communication system or the like.

  Generally, in wireless communication, automatic frequency control (hereinafter referred to as AFC: Auto Frequency Control) is used as a technique for compensating for a frequency error between a transmission frequency and a reception frequency caused by a product variation of a crystal oscillator (TCXO or the like) or a temperature change. It is done. As means for realizing the AFC, a spread spectrum signal receiving apparatus (see, for example, Patent Document 1), an automatic frequency control apparatus, and an automatic frequency control method (for example, see Patent Document 2) are provided.

  A conventional automatic frequency control device will be described below. A signal received by the receiving antenna (hereinafter referred to as a received signal) is input to the A / D converter via the receiving side amplifier and the receiving frequency converter. Of the output of the A / D converter, the pilot signal is despread by the pilot signal despreading unit, and the frequency error calculation unit calculates the amount of phase rotation of the despread pilot symbols at a constant symbol interval. The frequency error is calculated based on

Hereinafter, the frequency error calculation unit will be described. The first delay circuit delays the I component (R (t) * sin (θ (t))) of the pilot symbol by a plurality of symbols (R (t + Δt) * sin (θ (t + Δt))), and the first multiplier The pilot symbol Q component (R (t) * cos (θ (t))) is multiplied.
Similarly, the Q component (R (t) * cos (θ (t))) of the pilot symbol is delayed by a plurality of symbols in the second delay circuit (R (t + Δt) * cos (θ (t + Δt))), and the second multiplier Then, the I component (R (t) * sin (θ (t))) of the pilot symbol is multiplied. The two multiplication results are subtracted by a subtracter, and based on the result, the phase difference from the pilot symbols preceding a plurality of symbols is detected. The above calculation can be expressed as:
R (t) * sin (θ (t)) * R (t + Δt) * cos (θ (t + Δt))
−R (t + Δt) * sin (θ (t + Δt)) * R (t) * cos (θ (t))
= R (t) * R (t + Δt) * sin (θ (t) −θ (t + Δt))

The output of the frequency error calculation unit is averaged by the error average calculation unit. Based on the averaged frequency error (Δf), a control value (control frequency) for performing AFC is calculated by the AFC control value calculation unit.
As a calculation method of this control value, a method of fixing Δf from positive / negative to Δa, a method of changing frequency error Δf to + Δf, or classifying the frequency error Δf into n ranges by threshold values, and controlling according to the range. ± a _1, a ₂ value, and a method to · · · a _n.
The output of the AFC control value calculation unit is converted into a signal for controlling the TCXO by the TCXO control unit, and then the oscillation frequency of the TCXO is changed. This TCXO is a source oscillation of the reception unit synthesizer and the transmission unit synthesizer, and changes the oscillation frequency of the reception unit synthesizer and the oscillation frequency of the transmission unit synthesizer.
By changing the oscillation frequency of the receiving unit synthesizer, the frequency error of the received signal converted by the receiving frequency converter is corrected. At the same time, the transmission signal converted by the D / A converter is frequency-corrected in the same manner as the reception signal by the transmission frequency converter, and transmitted from the transmission antenna to the base station via the transmission side amplifier.

In this way, a series of feedback control units from the pilot channel despreading unit to the frequency error calculation unit, the error average calculation unit, the AFC control value calculation unit, and the TCXO control unit is referred to as an AFC control unit.
By such AFC feedback control, the frequency error between the transmission frequency and the reception frequency can be reduced.
Here, the frequency of the AFC feedback control is Δt × N when the frequency error is calculated by the frequency error calculator for each delay amount Δt of the delay circuit and averaged N times by the error average calculator. For example, if Δt = 4 symbols and N = 25 times, the AFC control cycle is every 100 symbols.

However, in the conventional AFC, the influence of the Doppler shift due to fading is not taken into account, and control is performed mainly taking into account the demodulation performance of the received signal of the mobile device, and the following problems arise.
When the mobile is moving, a frequency shift due to Doppler occurs. The Doppler shift amount (Fd) is recognized as a frequency error, and the frequency error (ΔTCXO) of the TCXO is further added to detect the frequency error Δf (= Fd + ΔTCXO).
In the prior art, AFC feedback control is performed to shift the oscillation frequency of the TCXO by Δf so that the frequency error Δf becomes 0 Hz.
When the AFC control is performed in this way, the frequency error of the received signal is reduced, which leads to an improvement in the demodulation performance of the received signal. However, as described above, the carrier frequency of the transmission signal is also shifted by Δf, and the same Doppler shift is also added to the transmission signal during movement. Therefore, the Doppler shift amount received by the base station is Fd + Δf = 2Fd + ΔTCXO, and a double Doppler shift amount is added to the base station. As a result, a large load is applied to the reception control of the base station, and reception and demodulation are difficult.

Japanese Patent Laid-Open No. 9-8699 JP 2002-26769 A

  Since the conventional automatic frequency control apparatus is configured as described above, when the mobile device is moving at a speed at which the influence of the Doppler shift becomes large, the communication performance of the mobile communication system including the base station and the mobile device. There has been a problem that it leads to deterioration of the product.

  The present invention has been made to solve the above-described problems. Even when a Doppler shift due to fading occurs, stable AFC that does not follow the Doppler shift is performed, and as a result, reception by both the mobile station and the base station is performed. An object of the present invention is to provide an automatic frequency control device capable of appropriately distributing deterioration and improving the communication performance of a mobile communication system.

An automatic frequency control device according to the present invention includes an error average calculation unit that calculates a frequency error for each cell or path, averaged for a certain period of time, and averages the frequency error for each cell or path. An AFC control value calculation unit that calculates an AFC error and calculates an AFC control value based on the AFC error, and a reception quality that measures a reception quality for each cell or each path and designates a cell or a path having a good reception quality A measurement unit, an error average selection unit that selects a frequency error of a cell or path designated by the reception quality measurement unit, and a communication state determination unit that determines whether the mobile device is in standby reception or continuous communication, When the state of the mobile device is waiting and receiving, the AFC control value calculation unit calculates the AFC control value using the frequency error selected by the error average selection unit .

  According to the present invention, it is possible to perform stable AFC that does not follow the Doppler shift, and as a result, it is possible to appropriately distribute reception degradation of both the mobile device and the base station, thereby improving the communication performance of the mobile communication system. Can be planned.

It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 3 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 4 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 5 of this invention. 10 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG. 9. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 6 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 7 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 8 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 9 of this invention. It is a flowchart which shows the operation | movement flow of AFC control value calculation in the automatic frequency control apparatus of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 10 of this invention. FIG. 20 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 11 of this invention. FIG. 22 is a conceptual diagram showing AFC error ΔTCXO calculation in the automatic frequency control device of FIG. 21. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 12 of this invention. It is a conceptual diagram illustrating a Delta] f _max, a method of selecting Delta] f _min in AFC control value calculating unit in Figure 23. The outputs Δf ₁ ,. . . , Δf _n spectrum. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 13 of this invention. FIG. 27 is a conceptual diagram illustrating a method of selecting Δf _max and Δf _min in an AFC control value calculation unit in FIG. 26. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 14 of this invention. FIG. 29 is a conceptual diagram illustrating calculation of an AFC error ΔTCXO in the automatic frequency control device of FIG. 28. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 15 of this invention. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 16 of this invention. It is a block diagram which shows the structure of the automatic frequency control apparatus which concerns on Embodiment 17 of this invention. It is a flowchart which shows the operation | movement flow of the frequency error selection in the automatic frequency control apparatus of FIG.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below. FIG. 1 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 1 of the present invention. In FIG. 1, a pilot channel despreading unit 101 despreads a pilot signal using a pilot channel spreading code.
The frequency error calculation unit 102 calculates a frequency error using the despread pilot symbols.
The error average calculation unit 103 averages the frequency error for a certain time.
The AFC control value calculation unit 104 calculates a control value (control frequency) for performing AFC based on the average value of frequency errors and the moving speed detection value that is the output of the speed detection unit 106.
The TCXO control unit 105 generates a signal for performing TCXO control based on the AFC control value.
The speed detector 106 detects the moving speed of the mobile device. As a speed detection method in the speed detection unit 106, detection is performed using pilot symbols in the first embodiment, but in addition, a method of demodulating a received signal and detecting it from position information, or detection from GPS position information It may be a method. In the present invention, the speed detection method is not particularly limited as long as it is a means for detecting the moving speed of the mobile device.
The comparator 107 determines the moving speed detected by the speed detection unit 106 as a threshold value.

  Next, the operation will be described. Of the received signal, the pilot signal is despread by pilot channel despreading section 101 and output to frequency error calculation section 102. The frequency error calculation unit 102 calculates a phase rotation amount at a fixed symbol interval of the despread pilot symbols, and calculates a frequency error based on the phase rotation amount. The error average calculation unit 103 averages the frequency error calculated by the frequency error calculation unit 102 for a certain period of time. The speed detection unit 106 detects the moving speed of the mobile device using the pilot symbols, performs threshold determination by the comparator 107, and then outputs it to the AFC control value calculation unit 104. The AFC control value calculation unit 104 calculates a frequency to be AFC (hereinafter referred to as an AFC control value), that is, a frequency for controlling the TCXO, based on the threshold determination result in the comparator 107.

FIG. 2 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 2, the speed detector 106 detects the moving speed (v) of the mobile device (step ST201).

  The comparator 107 compares and determines the absolute value (| v |) of the moving speed and the threshold value (Th_v) of the moving speed (step ST202). If | v |> Th_v, the process proceeds to step ST203; otherwise, the process proceeds to step ST204.

In step ST203, it is determined that a Doppler shift has occurred due to fading, and the AFC control value calculation unit 104 sets the AFC control value to be smaller than normal.
For example, when the normal AFC control value is ± a, when it is determined that the detected moving speed is greater than or equal to the threshold value, the normal AFC control value is multiplied by a constant less than 1 to obtain ± K * a , (K <1).

  In step ST204, it is determined that no Doppler shift has occurred, and the AFC control value calculation unit 104 sets the AFC control value to ± K * a, (K = 1).

  The TCXO control unit 105 generates a signal for performing TCXO control based on the AFC control value calculated by the AFC control value calculation unit 104 (step ST205).

Here, a plurality of movement speed thresholds are set (Th_v ₁ ,..., Th_v _n ), and the corresponding AFC control values ± K ₁ * a,. . . , ± K _n * a. At this time, 1> K ₁ . . . > K _n > 0, Th_v ₁ <. . . If <Th_v _n , an operation for decreasing the AFC control value as the speed increases becomes possible.

  For example, the threshold for changing the AFC control value is a moving speed of 100 km / h, the AFC control value is ± 20 Hz for speeds below this threshold, and ± 2 Hz for speeds above the threshold. Thus, by changing the feedback loop gain of AFC, it becomes possible to delay the tracking of AFC when the moving speed is 100 km / h or more. Accordingly, it is possible to perform stable AFC that does not follow the Doppler shift, and as a result, it is possible to appropriately distribute reception degradation of both the mobile device and the base station, and to improve the communication performance of the mobile communication system. .

As a prior art of the same type, there is one described in Patent Document 2. In Embodiment 7 of Patent Document 2, the number of AFCs within a predetermined time is changed by changing the timing of frequency error value calculation according to the detected moving speed. As a result, when the moving speed is slow, the number of AFCs within a certain time is increased, and the AFC pulling speed is increased.
Considering the opposite, it is considered that AFC that does not follow the Doppler shift can be realized by reducing the number of AFC within a certain time when the moving speed is high, but if the moving speed is slow, control within a certain time is possible. Since the number of times is increased, the signal observation time used per control is shortened, and the average effect is lost and the error increases. That is, there is a problem that accuracy of frequency error calculation per time is impaired.
On the other hand, in the first embodiment, by changing the AFC control amount per time without changing the number of times of control within a predetermined time, the follow-up property to the Doppler shift is maintained while maintaining the accuracy of frequency error calculation. The point that can be suppressed.

As described above, according to the first embodiment, the AFC control value is changed based on the moving speed. When the moving speed is equal to or higher than the threshold value, the AFC control value becomes small. That is, the feedback loop gain of AFC is reduced.
Accordingly, it is possible to perform stable AFC that does not follow the Doppler shift, and as a result, it is possible to appropriately distribute reception degradation of both the mobile device and the base station, and to improve the communication performance of the mobile communication system. .

Embodiment 2. FIG.
The second embodiment of the present invention will be described below. FIG. 3 is a block diagram showing the configuration of the automatic frequency control apparatus according to Embodiment 2 of the present invention. In the second embodiment, the speed detection unit 106 of the first embodiment is replaced with a Doppler shift detection unit 201, and the comparator 107 is replaced with a comparator 207 that performs threshold determination of the Doppler shift amount. Since other configurations are the same as those of the first embodiment (FIG. 1), description thereof is omitted.

In FIG. 3, a Doppler shift detection unit 201 detects a Doppler shift amount from a pilot symbol that is an output of the pilot channel despreading unit 101. As a detection method, there are a method of detecting from the output level of a filter bank using a plurality of band pass filters, a method of obtaining a pilot symbol by Fourier transform, and the like. In the present invention, the method for detecting the Doppler shift amount is not particularly limited.
Further, the comparator 207 determines a threshold value for the amount of Doppler shift detected by the Doppler shift detector 201.

Next, the operation will be described. FIG. 4 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 4, the Doppler shift detector 201 detects the Doppler shift amount (Fd) (step ST401).

  Comparator 207 compares and determines the absolute value (| Fd |) of the Doppler shift amount and the threshold value (Th_Fd) of the Doppler shift amount (step ST402). If | Fd |> Th_Fd, the process proceeds to step ST403; otherwise, the process proceeds to step ST404.

  In step ST403, it is determined that a Doppler shift has occurred due to fading, and the AFC control value calculation unit 104 sets the AFC control value to be smaller than normal. For example, when it is determined that the detected Doppler shift amount is greater than or equal to the threshold, the AFC control value is set to ± K * a, (K <1).

  In step ST404, it is determined that no Doppler shift has occurred, and the AFC control value calculation unit 104 sets the AFC control value to ± K * a, (K = 1).

  TCXO control section 105 generates a signal for performing TCXO control based on the AFC control value calculated by AFC control value calculation section 104 (step ST405).

Here, a plurality of threshold values for the Doppler shift amount are set (Th_Fd ₁ ,..., Th_Fd _n ), and the corresponding AFC control values ± K ₁ * a,. . . , ± K _n * a. At this time, 1> K ₁ . . . > K _n > 0, Th_Fd ₁ <. . . <When Th_Fd _n, allowing operation to lessen AFC control value as the Doppler shift amount increases.

As described above, according to the second embodiment, since the AFC control value is changed based on the Doppler shift amount, the AFC control value becomes small when the Doppler shift amount is a certain value or more. That is, the feedback loop gain of AFC is reduced.
Therefore, as in the first embodiment, it is possible to perform stable AFC that does not follow the Doppler shift, and as a result, it is possible to appropriately distribute reception degradation of both the mobile station and the base station, and Communication performance can be improved.

Embodiment 3 FIG.
The third embodiment of the present invention will be described below. FIG. 5 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 3 of the present invention. In the third embodiment, the comparator 207 of the second embodiment is replaced with a comparator 307 that receives the outputs of the error average calculation unit 103 and the Doppler shift detection unit 201, and the calculation method of the AFC control value calculation unit 104 is changed. The AFC control value calculation unit 304 is replaced. Since other configurations are the same as those of the second embodiment (FIG. 3), description thereof is omitted.

In FIG. 5, the comparator 307 compares and determines the Doppler shift amount that is the output of the Doppler shift detection unit 201 and the frequency error that is the output of the error average calculation unit 103.
In addition, the AFC control value calculation unit 304 sets an AFC control value based on the determination result of the comparator 307.

Next, the operation will be described. FIG. 6 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 6, the average error calculation unit 103 calculates a frequency error (Δf) (step ST601).
The Doppler shift detector 201 detects the Doppler shift amount (Fd) (step ST602).

  Comparator 307 compares and determines the absolute value (| Δf |) of the frequency error and the absolute value (| Fd |) of the Doppler shift amount (step ST603). If | Δf |> | Fd |, the process proceeds to step ST604; otherwise, the process proceeds to step ST605.

  In step ST604, the comparator 307 outputs control information to the AFC control value calculation unit 304. It is determined that a frequency error has occurred due to a factor other than Doppler shift (temperature deviation or the like), and the AFC control value calculation unit 304 sets the AFC control value to ± K * a, (K = 1).

  In step ST605, it is determined that no frequency error has occurred due to a factor other than Doppler shift, and the AFC control value calculation unit 304 sets the AFC control value to ± K * a, (K = 0). That is, AFC is not performed.

  TCXO control section 105 generates a signal for performing TCXO control based on the AFC control value calculated by AFC control value calculation section 304 (step ST606).

  As described above, according to the third embodiment, when the frequency error exceeds the Doppler shift amount, it is determined that the frequency error has occurred due to a factor other than the Doppler shift, and does not follow the Doppler shift due to fading. AFC that follows the frequency error of other factors can be realized.

Embodiment 4 FIG.
The fourth embodiment of the present invention will be described below. FIG. 7 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 4 of the present invention. In the fourth embodiment, the AFC control value calculation unit 304 in the third embodiment is replaced with an AFC control value calculation unit 404 with a different calculation method. Other configurations are the same as those of the third embodiment (FIG. 5), and thus description thereof is omitted.

Next, the operation will be described. FIG. 8 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG. In FIG. 8, only step ST804 that is different from the third embodiment (FIG. 6) will be described.
In step ST803, when the frequency error (Δf) exceeds the Doppler shift amount (Fd), it is determined that the frequency error has occurred due to a factor other than the Doppler shift, and the AFC control value calculation unit 404 sets the AFC control value to ± (| Δf | − | Fd |) is set (step ST804).

  As described above, according to the fourth embodiment, it is possible to immediately pull in the frequency error due to factors other than the Doppler shift, and the frequency error tracking speed can be improved.

Embodiment 5 FIG.
The fifth embodiment of the present invention will be described below. FIG. 9 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 5 of the present invention. In the fifth embodiment, the AFC control value calculation unit 304 of the third embodiment is replaced with an AFC control value calculation unit 504 in which the calculation method is changed. Other configurations are the same as those of the third embodiment (FIG. 5), and thus description thereof is omitted.

Next, the operation will be described. FIG. 10 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG. In FIG. 10, only steps ST1004 and 1005 different from the third embodiment (FIG. 6) will be described.
In step ST1003, when the frequency error (Δf) exceeds the Doppler shift amount (Fd) (| Δf |> | Fd |), the AFC control value calculation unit 504 sets the AFC control value larger than usual. For example, when the normal AFC control value is ± a, the AFC control value is set as ± K * a, (K> 1) (step ST1004).

  If the frequency error (Δf) does not exceed the Doppler shift amount (Fd) in step ST1003, the AFC control value calculation unit 504 sets the AFC control value as ± K * a, (K = 1) (step ST1003). ST1005).

  As described above, according to the fifth embodiment, when the frequency error Δf exceeds the Doppler shift amount Fd, it is determined that a frequency error has occurred due to a factor (temperature deviation or the like) other than the Doppler shift. By increasing the AFC control amount per time, the pull-in speed can be increased (the AFC feedback loop gain is increased), and the frequency error tracking speed can be improved. That is, it does not follow the Doppler shift due to fading, but when a frequency error due to other factors occurs, the tracking speed of the frequency error can be improved.

Embodiment 6 FIG.
The sixth embodiment of the present invention will be described below. FIG. 11 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 6 of the present invention. In the sixth embodiment, the error average calculation unit 103 of the fifth embodiment is replaced with an error average calculation unit 603 that can change the average calculation interval, and the AFC control value calculation unit 504 is replaced with an AFC control value calculation unit 604. is there. Since other configurations are the same as those of the fifth embodiment, the description thereof is omitted.
In FIG. 11, an error average calculation unit 603 averages the frequency error for a fixed time, and changes this averaging time (T_ave).
The AFC control value calculation unit 604 sets the AFC control value to ± a.

Next, the operation will be described. FIG. 12 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 12, the error average calculator 603 calculates a frequency error (Δf) (step ST1201).
The Doppler shift detection unit 201 detects the Doppler shift amount (Fd) (step ST1202).

  Comparator 307 compares and determines the absolute value of the frequency error (| Δf |) and the absolute value of the Doppler shift amount (| Fd |) (step ST1203). If | Δf |> | Fd |, the process proceeds to step ST1204; otherwise, the process proceeds to step ST1205.

In step ST1204, the comparator 307 outputs control information to the error average calculation unit 603, and the error average calculation unit 603 sets the averaging time (T_ave) to be shorter than normal time (when the frequency error is equal to or less than the Doppler shift amount). To do.
For example, assuming that the normal averaging time is T_ave = T _a , when it is determined that Δf exceeds Fd, the averaging time is set to T_ave = T _b , (T _a > T _b ) and the averaging time is shortened. . This shortens the AFC control cycle, increases the AFC pull-in speed, and improves the frequency error tracking speed.

In step ST1205, the error average calculation section 603 sets the averaging time to normal T_ave = T _a , (T _a > T _b ).

  As described above, according to the sixth embodiment, as in the fifth embodiment, when the frequency error (Δf) exceeds the Doppler shift amount (Fd) (| Δf |> | Fd |), the Doppler Judging that a frequency error has occurred due to factors other than shift (temperature deviation, etc.), shortening the AFC control cycle increases the pull-in speed (increases the AFC feedback loop gain), and increases the frequency error tracking speed. Can be improved. That is, it does not follow the Doppler shift due to fading, but when a frequency error due to other factors occurs, the tracking speed of the frequency error can be improved.

Embodiment 7 FIG.
The seventh embodiment of the present invention will be described below. FIG. 13 is a block diagram showing the configuration of the automatic frequency control apparatus according to the seventh embodiment of the present invention. In the seventh embodiment, the speed detection unit 106 and the comparator 107 of the first embodiment are replaced with a radio link addition / deletion determination unit 709, and the AFC control value calculation unit 104 is replaced with an AFC control value calculation unit 704. . Since other configurations are the same as those of the first embodiment (FIG. 1), description thereof is omitted.
In FIG. 13, the radio link addition / deletion determination unit 709 outputs a trigger signal when the addition or deletion of the radio link occurs.
The AFC control value calculation unit 704 receives the trigger signal from the Radio Link addition / deletion determination unit 709 and calculates an AFC control value.

The addition / deletion of Radio Link will be described below. The CDMA system has an SHO (soft handover) function for performing simultaneous communication with a plurality of base stations. Communication connection / disconnection to / from individual base stations is referred to as “Radio Link addition / deletion”.
When a radio link is added or deleted by high-speed movement, a large frequency error is observed due to a difference in Doppler shift between a base station that moves away and a base station that approaches. However, an automatic frequency control device that operates to the extent that it does not follow the Doppler shift cannot quickly follow the frequency error.

  Therefore, in the seventh embodiment, when the radio link is added or deleted in the automatic frequency control apparatus (the automatic frequency control apparatus according to the first to sixth embodiments) operating so as not to follow the Doppler shift, the AFC control is performed. Set the value higher than normal.

Next, the operation will be described. FIG. 14 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 14, the error average calculation unit 103 calculates a frequency error (Δf) (step ST1401).

  Radio Link addition / deletion determination section 709 determines addition / deletion of Radio Link based on the magnitude of frequency error (Δf) (step ST1402). If Δf is large, it is determined that Radio Link has been added / deleted, and the process proceeds to step ST1403. Otherwise, the process proceeds to step ST1404. Examples of the magnitude determination of Δf include threshold determination.

  In step ST1403, when the Radio Link is added / deleted, the AFC control value calculation unit 704 sets the AFC control value as ± K * a, (K> 1).

  In step ST1404, the AFC control value calculation unit 704 sets the AFC control value as ± K * a, (K = 1).

  TCXO control section 105 generates a signal for performing TCXO control based on the AFC control value calculated by AFC control value calculation section 704 (step ST1405).

  As described above, according to the seventh embodiment, even in an automatic frequency control device that normally operates to the extent that it does not follow the Doppler shift, the frequency error that occurs when a radio link is added or deleted with high-speed movement. On the other hand, it becomes possible to pull in at high speed.

Embodiment 8 FIG.
The eighth embodiment of the present invention will be described below. FIG. 15 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 8 of the present invention. In the eighth embodiment, the error average calculation unit 803 is used as the output destination of the radio link addition / deletion determination unit 709 in the seventh embodiment. Further, the AFC control value calculation unit 704 is replaced with an AFC control value calculation unit 804. Other configurations are the same as those of the seventh embodiment (FIG. 13), and thus the description thereof is omitted.
In FIG. 15, an error average calculation unit 803 averages the frequency error for a certain period of time, and changes the averaging time.
The AFC control value calculation unit 804 sets the AFC control value to ± a.

  The purpose of the eighth embodiment is the same as that of the seventh embodiment. In the automatic frequency control device (the automatic frequency control device of the first to sixth embodiments) operating so as not to follow the Doppler shift, the addition of the radio link is performed. Alternatively, when the deletion is performed, the averaging time of the error average calculation unit 803 is set shorter than the normal time (when the frequency error is equal to or less than the Doppler shift amount).

Next, the operation will be described. FIG. 16 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 16, the error average calculator 603 calculates the frequency error (Δf) (step ST1601).

  Radio Link addition / deletion determination section 709 performs addition / deletion determination of Radio Link based on the magnitude of frequency error (Δf) (step ST1602). If Δf is large, it is determined that the radio link has been added / deleted, and the process proceeds to step ST1603. Otherwise, the process proceeds to step ST1604. Examples of the magnitude determination of Δf include threshold determination.

In Step ST1603, the Radio Link addition / deletion determination unit 709 outputs control information to the error average calculation unit 803, and the error average calculation unit 803 sets the averaging time (T_ave) to normal (the frequency error is equal to or less than the Doppler shift amount). ) Set shorter. For example, assuming that the normal averaging time is T_ave = T _a , when it is determined that the Radio Link has been added / deleted, the averaging time is set as T_ave = T _b , (T _a > T _b ). This shortens the AFC control cycle, increases the AFC pull-in speed, and improves the frequency error tracking speed.

In step ST1604, the error average calculation section 803 sets the averaging time to normal T_ave = T _a , (T _a > T _b ).

  As described above, according to the eighth embodiment, even in an automatic frequency control device that normally operates to the extent that it does not follow the Doppler shift, the frequency error that occurs when adding or deleting a Radio Link with high-speed movement is eliminated. On the other hand, it becomes possible to pull in at high speed.

Embodiment 9 FIG.
The ninth embodiment of the present invention will be described below. FIG. 17 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 9 of the present invention. In FIG. 17, the description of the same reference numerals as those already described is omitted.
The frequency error storage unit 906 stores a frequency error that is an output of the error average calculation unit 103.
The comparator 907 outputs a trigger signal when the difference between the frequency error output from the error average calculation unit 103 and the previous frequency error output from the frequency error storage unit 906 exceeds a threshold value.
The AFC control value calculation unit 904 receives the trigger signal from the comparator 907 and calculates an AFC control value.

  The purpose of the ninth embodiment is the same as that of the seventh and eighth embodiments. In the automatic frequency control device (the automatic frequency control device of the first to sixth embodiments) operating to the extent that it does not follow the Doppler shift, If the difference between the current frequency error and the previous frequency error that exceeds the threshold value exceeds the threshold, it is determined that Radio Link has been added or deleted, and the AFC control value is set larger than normal.

Next, the operation will be described. FIG. 18 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 18, the error average calculation unit 103 calculates the current frequency error (Δf). Further, frequency error storage section 906 outputs the previous frequency error (Δf _n-1 ) stored (step ST1801).

Comparator 907 determines whether or not the absolute value of the difference between the current frequency error (Δf _n ) and the previous frequency error (Δf _n−1 ) exceeds a threshold value (Th_Δf) (step ST1802). If | Δf _n −Δf _n−1 |> Th_Δf, the process proceeds to step ST1803. Otherwise, the process proceeds to step ST1804.

  In step ST1803, it is determined that the Radio Link has been added or deleted, and the AFC control value calculation unit 904 sets the AFC control value as ± K * a, (K> 1).

  In Step ST1804, the AFC control value calculation unit 904 sets the AFC control value as ± K * a, (K = 1).

  TCXO control section 105 generates a signal for performing TCXO control based on the AFC control value calculated by AFC control value calculation section 904 (step ST1805).

  As described above, according to the ninth embodiment, even in an automatic frequency control device that normally operates to the extent that it does not follow the Doppler shift, the frequency error that occurs when a radio link is added or deleted with high-speed movement. On the other hand, it becomes possible to pull in at high speed.

Embodiment 10 FIG.
The tenth embodiment of the present invention will be described below. FIG. 19 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 10 of the present invention. In the tenth embodiment, the output destination of the comparator 907 in the ninth embodiment is the error average calculation unit 1003. Further, the AFC control value calculation unit 904 is replaced with an AFC control value calculation unit 1004. Since other configurations are the same as those of the ninth embodiment (FIG. 17), description thereof is omitted.

In FIG. 17, an error average calculation unit 1003 averages the frequency error for a certain time, and changes the averaging time.
The AFC control value calculation unit 1004 sets the AFC control value to ± a.

  The purpose of the tenth embodiment is the same as that of the seventh to ninth embodiments. In the automatic frequency control device (the automatic frequency control device of the first to sixth embodiments) operating to the extent that it does not follow the Doppler shift, If the difference between the error frequency and the previous frequency error exceeds a certain value, it is determined that the Radio Link has been added or deleted, and the averaging time of the error average calculation unit 1003 is set to the normal time (the difference between the frequency error and the previous frequency error). If the difference is less than or equal to the threshold), set it shorter.

Next, the operation will be described. FIG. 20 is a flowchart showing an operation flow of AFC control value calculation in the automatic frequency control device of FIG.
In FIG. 20, the error average calculation unit 1003 calculates the current frequency error (Δf). Further, the frequency error storage unit 906 outputs the stored previous frequency error (Δf _n-1 ) (step ST2001).

Comparator 907 determines whether or not the absolute value of the difference between the current frequency error (Δf _n ) and the previous frequency error (Δf _n-1 ) exceeds a threshold value (Th_Δf) (step ST2002). If | Δf _n −Δf _n−1 |> Th_Δf, the process proceeds to step ST2003; otherwise, the process proceeds to step ST2004.

In step ST2003, the comparator 907 outputs control information to the error average calculation unit 1003, and the error average calculation unit 1003 sets the averaging time (T_ave) from the normal time (| Δf _n −Δf _n−1 | ≦ Th_Δf). Set it short. For example, assuming that the normal averaging time is T_ave = T _a , when it is determined that the Radio Link has been added / deleted, the averaging time is set as T_ave = T _b , (T _a > T _b ). This shortens the AFC control cycle, increases the AFC pull-in speed, and improves the frequency error tracking speed.

In step ST2004, the error average calculation section 1003 sets the averaging time to normal T_ave = T _a , (T _a > T _b ).

  As described above, according to the tenth embodiment, even in an automatic frequency control device that normally operates to the extent that it does not follow the Doppler shift, the frequency error that occurs when a radio link is added or deleted with high-speed movement. On the other hand, it becomes possible to pull in at high speed.

Embodiment 11 FIG.
The eleventh embodiment of the present invention will be described below. FIG. 21 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 11 of the present invention. In FIG. 21, the description of the same reference numerals as those already described is omitted.
The frequency error calculation unit 1102 calculates the frequency error of each cell using each pilot symbol of a plurality of neighboring cells (Cell) despread by the pilot channel despreading unit 101.
The error average calculation unit 1103 averages the frequency error of each cell from the frequency error calculation unit 1102 for a certain period of time.
The AFC control value calculation unit 1104 performs weighted averaging using the output of the error average calculation unit 1103 to calculate an AFC error. Then, an AFC control value is calculated using an AFC error.

ここでａ₁，．．．，ａ_nは、各セルの信号レベルに比例した重み付けや、ａ₁，．．．，ａ_n＝１とする単純平均等が考えられる。 Next, the operation will be described. FIG. 22 is a conceptual diagram showing calculation of AFC error ΔTCXO in the automatic frequency control device of FIG. For example, as shown in FIG. 22, when the mobile station 9202 receives signals from a plurality of base stations 9201, the frequency error (Δf ₁ ,..., Δf _{n of} each cell corresponding to communication with each base station is received. ) Is observed.
This Δf ₁ ,. . . , Δf _n are weighted and averaged by weighting coefficients (a ₁ ,..., A _n ), an AFC error (ΔTCXO) is calculated as shown in Equation 1.

Where a ₁ ,. . . , _An are weights proportional to the signal level of each cell, and a ₁ ,. . . , A _n = 1, and so on.

  As described above, according to the eleventh embodiment, by averaging the frequency errors of a plurality of cells, there is an effect of averaging the Doppler shift, and stable AFC control that hardly follows the Doppler shift can be performed. Become.

Embodiment 12 FIG.
The twelfth embodiment of the present invention will be described below. FIG. 23 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 12 of the present invention. In the twelfth embodiment, the AFC control value calculation unit 1104 in the eleventh embodiment is replaced with an AFC control value calculation unit 1204. Other configurations are the same as those of the eleventh embodiment (FIG. 21), and thus the description thereof is omitted.

Next, the operation will be described. The AFC control value calculation unit 1204 calculates the maximum value (Δf _max ) and the minimum value (Δf _min ) from the frequency error (Δf ₁ ,..., Δf _n ) of each cell that is the output of the error average calculation unit 1103. Select and perform a weighted average using Δf _max and Δf _min to calculate an AFC error (ΔTCXO). Then, an AFC control value is calculated using an AFC error.

ここで、ｂ_max，ｂ_minは、各セルの信号レベルに比例した重み付けや、ｂ_max，ｂ_min＝１とする単純平均等が考えられる。 FIG. 24 is a conceptual diagram illustrating a method of selecting Δf _max and Δf _min in the AFC control value calculation unit 1204 in FIG. In FIG. 24, Δf ₁ ,... For each frequency error average calculation time (Δt) in the error average calculation unit 1103. . . , Δf _n , Δf _max and Δf _min are selected.
When Δf _max and Δf _min are weighted and averaged by weighting coefficients (b _max , b _min ), ΔTCXO is calculated as shown in Equation 2.

Here, b _max and b _min may be weighted in proportion to the signal level of each cell, or a simple average with b _max and b _min = 1.

25 shows the outputs Δf ₁ ,... Of the frequency error calculation unit 1102 in FIG. . . , Δf _n spectrum. In FIG. 25, there is a frequency error (center ΔTCXO) due to an AFC error (ΔTCXO), the maximum Doppler frequency (Fd) spreads around this, and there is a component with a strong level corresponding to a direct wave. The frequency of the direct wave is determined by the moving speed and the arrival angle of the mobile device, and the frequency varies between ΔTCXO + Fd to ΔTCXO−Fd.
Removing the influence of the direct wave from such received signal, to detect DerutaTCXO measures Delta] f _max and Delta] f _min of the frequency, by calculating the _{ΔTCXO = (Δf max + Δf min} ) / 2, it is precisely DerutaTCXO Calculated. This can be calculated by setting b _max and b _min = 1 in Equation 2.

As described above, according to the twelfth embodiment, the AFC error (ΔTCXO) can be calculated with high accuracy by averaging the maximum value (Δf _max ) and the minimum value (Δf _min ) of the frequency error.
In addition, the measurement accuracy can be improved by observing signals from a plurality of cells, and the Doppler shift can be averaged, thereby enabling stable AFC control that is difficult to follow the Doppler shift. Become.
Furthermore, if Fd = (Δf _max −Δf _min ) / 2 is calculated here, the maximum Doppler frequency (Fd) can be calculated at the same time, and the AFC error (ΔTCXO) and the maximum Doppler frequency (Fd) An automatic frequency control device capable of simultaneously detecting

Embodiment 13 FIG.
The thirteenth embodiment of the present invention will be described below. FIG. 26 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 13 of the present invention. In the thirteenth embodiment, the AFC control value calculation unit 1204 in the twelfth embodiment is changed to an AFC control value calculation unit 1304. Other configurations are the same as those of the twelfth embodiment (FIG. 23), and thus the description thereof is omitted.

Next, the operation will be described. The AFC control value calculation unit 1304 observes the output (Δf ₁ ,..., Δf _n ) of the error average calculation unit 1103 for a certain time (ΔT), and calculates the maximum value (Δf _max) from Δf of all cells within the certain time. ) And the minimum value (Δf _min ), and AFC error (ΔTCXO) is calculated by performing weighted averaging using Δf _max and Δf _min . Then, an AFC control value is calculated using an AFC error.

FIG. 27 is a conceptual diagram showing a method of selecting Δf _max and Δf _min in the AFC control value calculation unit 1304 in FIG. In FIG. 27, the frequency error (Δf ₁ ,..., Δf _n ) of each cell output every average calculation time (Δt) of the error average calculation unit 1103 is observed for a certain time (ΔT), and this certain time ( The maximum value (Δf _max ) and the minimum value (Δf _min ) are selected from the observed values in ΔT).
When Δf _max and Δf _min are weighted and averaged by weighting coefficients (b _max , b _min ), an AFC error is calculated as shown in Equation 2.
Here, b _max and b _min may be weighted in proportion to the signal level of each cell, or a simple average with b _max and b _min = 1.

As shown in FIG. 25, the spectrum of the output of the error average calculation unit 1103 has a frequency error (center ΔTCXO) due to an AFC error (ΔTCXO), and the maximum Doppler frequency (Fd) spreads around this. In addition, there is a strong component corresponding to a direct wave.
Furthermore, the direct wave is dominant in the environment with good visibility, and the spread of the maximum Doppler frequency (Fd) cannot be observed by measuring the maximum value (Δf _max ) and the minimum value (Δf _min ) in a short time. Therefore, ΔTCXO cannot be measured with high accuracy.

Therefore, if the maximum value (Δf _max ) and the minimum value (Δf _min ) are obtained from the observed value of the time (ΔT) that the angle of arrival sufficiently changes from the front to the rear, ΔTCXO compared to the twelfth embodiment. The calculation accuracy of can be improved.

As described above, according to the thirteenth embodiment, the maximum value (Δf _max ) and the minimum value (Δf _min ) are obtained from the observed value of the time (ΔT) that the arrival angle sufficiently changes from the front to the rear. Thus, the calculation accuracy of ΔTCXO can be improved as compared with the twelfth embodiment.
Further, by selecting the maximum value (Δf _max ) and the minimum value (Δf _min ) at a certain time (ΔT), ΔTCXO can be accurately measured even in the case of one cell.
Furthermore, by observing signals from a plurality of cells, the measurement accuracy is improved and the Doppler shift is averaged, so that stable AFC control that hardly follows the Doppler shift can be performed.
Similar to the eleventh embodiment, if Fd = (Δf _max −Δf _min ) / 2 is calculated, the maximum Doppler frequency (Fd) can be calculated simultaneously, and the error (ΔTCXO) of the AFC and the maximum Doppler frequency are calculated. An automatic frequency control device capable of simultaneously detecting (Fd) can be realized.

Embodiment 14 FIG.
The fourteenth embodiment of the present invention will be described below. FIG. 28 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 14 of the present invention. In the fourteenth embodiment, the frequency error calculation unit 1102 in the eleventh embodiment is replaced with a frequency error calculation unit 1402. Other configurations are the same as those in the eleventh embodiment (FIG. 21), and thus the description thereof is omitted.

Next, the operation will be described. Frequency error calculation section 1402 calculates the frequency error of each path using each pilot symbol of a plurality of paths (Path) despread by pilot channel despreading section 101.
The error average calculation unit 1103 averages the frequency error of each path from the frequency error calculation unit 1402 for a certain period of time.
The AFC control value calculation unit 1104 performs weighted averaging using the outputs (Δf ₁ ,..., Δf _n ) of the error average calculation unit 1103 of each path, and calculates an AFC error (ΔTCXO). Here, the method of calculating the AFC error (ΔTCXO) is the same as in the eleventh embodiment. Then, an AFC control value is calculated using an AFC error.

FIG. 29 is a conceptual diagram showing AFC error ΔTCXO calculation in the automatic frequency control device of FIG. For example, as shown in FIG. 29, when the mobile station 9202 receives a multipath signal from the base station 9201, the frequency error (Δf ₁ ,..., Δf _n ) for each path with different arrival angles is observed.
This Δf ₁ ,. . . , Δf _n are weighted and averaged with weighting coefficients (a ₁ ,..., A _n ), and the AFC error (ΔTCXO) is calculated as in Equation 1.
Where a ₁ ,. . . , _An are weights proportional to the signal level of each path, a ₁ ,. . . , A _n = 1, and so on.

As described above, according to the fourteenth embodiment, by using the multipath detection function that is a feature of CDMA, by observing a different frequency error for each path, the measurement accuracy is improved as compared with the eleventh embodiment. It becomes possible to improve.
Further, even in the case of one cell, it is possible to improve measurement accuracy by observing signals of a plurality of paths.
Furthermore, since the effect of averaging the Doppler shift is increased, stable AFC control that is difficult to follow the Doppler shift becomes possible.

Embodiment 15 FIG.
The fifteenth embodiment of the present invention will be described below. FIG. 30 is a block diagram showing the configuration of the automatic frequency control apparatus according to the fifteenth embodiment of the present invention. In the fifteenth embodiment, the AFC control value calculation unit 1104 in the fourteenth embodiment is changed to the AFC control value calculation unit 1204 in the twelfth embodiment. Other configurations are the same as those in the fourteenth embodiment (FIG. 28), and thus description thereof is omitted.

Next, the operation will be described. The AFC control value calculation unit 1204 selects the maximum value (Δf _max ) and the minimum value (Δf _min ) from the outputs (Δf ₁ ,..., Δf _n ) of the error average calculation unit 1103 for each path, and Δf _A weighted average is performed using _max and Δf _min to calculate an AFC error (ΔTCXO). Here, the method of calculating the AFC error (ΔTCXO) is the same as in the twelfth embodiment. Then, an AFC control value is calculated using an AFC error.

In Embodiment 12, it has been described that ΔTCXO can be calculated with high accuracy by averaging the maximum value (Δf _max ) and the minimum value (Δf _min ) from the frequency errors of a plurality of cells for each average calculation time (Δt).
In the fifteenth embodiment, frequency errors of a plurality of paths are observed using a multipath detection function that is a feature of CDMA, and a maximum value (Δf _max ) and a minimum value (Δf _min ) of frequency errors for each average calculation time (Δt). ) To calculate ΔTCXO with higher accuracy.

As described above, according to the fifteenth embodiment, it is possible to improve measurement accuracy by observing different frequency errors for each path using the multipath detection function. Further, even in the case of one cell, it is possible to improve measurement accuracy by observing signals of a plurality of paths.
In addition, since the effect of averaging the Doppler shift increases, stable AFC control that hardly follows the Doppler shift can be performed.
Furthermore, if Fd = (Δf _max −Δf _min ) / 2 is calculated here, the maximum Doppler frequency (Fd) can be calculated at the same time, and the AFC error (ΔTCXO) and the maximum Doppler frequency (Fd) An automatic frequency control device capable of simultaneously detecting

Embodiment 16 FIG.
The sixteenth embodiment of the present invention will be described below. FIG. 31 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 16 of the present invention. In the sixteenth embodiment, the AFC control value calculation unit 1204 in the fifteenth embodiment is changed to the AFC control value calculation unit 1304 in the thirteenth embodiment. Other configurations are the same as those of the fifteenth embodiment (FIG. 30), and thus description thereof is omitted.

Next, the operation will be described. The AFC control value calculation unit 1304 observes the output (Δf ₁ ,..., Δf _n ) of the error average calculation unit 1103 of each path for a certain time (ΔT), and calculates the maximum from the observation values of all the cells within the certain time. An AFC error (ΔTCXO) is calculated by selecting a value (Δf _max ) and a minimum value (Δf _min ) and performing a weighted average using Δf _max and Δf _min . Here, the method of calculating the AFC error (ΔTCXO) is the same as in the thirteenth embodiment. Then, an AFC control value is calculated using an AFC error.

In the thirteenth embodiment, it has been described that ΔTCXO can be calculated with high accuracy by selecting and averaging the maximum value (Δf _max ) and the minimum value (Δf _min ) in a certain time (ΔT). In the sixteenth embodiment, the frequency error of a plurality of paths is observed using the multipath detection function that is a feature of CDMA, and the maximum value (Δf _max ) and the minimum value of the frequency errors of all paths in a certain time (ΔT). By averaging (Δf _min ), ΔTCXO is calculated with higher accuracy.

As described above, according to the sixteenth embodiment, it is possible to improve measurement accuracy by observing different frequency errors for each path using the multipath detection function. Further, even in the case of one cell, it is possible to improve measurement accuracy by observing signals of a plurality of paths. Furthermore, by selecting the maximum value (Δf _max ) and the minimum value (Δf _min ) at a certain time (ΔT), ΔTCXO can be accurately measured even in the case of one pass.
From the above, the effect of averaging the Doppler shift is further increased, and stable AFC control that is difficult to follow the Doppler shift becomes possible.
Furthermore, if Fd = (Δf _max −Δf _min ) / 2 is calculated here, the maximum Doppler frequency (Fd) can be calculated at the same time, and the AFC error (ΔTCXO) and the maximum Doppler frequency (Fd) An automatic frequency control device capable of simultaneously detecting

Embodiment 17. FIG.
The seventeenth embodiment of the present invention will be described below. FIG. 32 is a block diagram showing a configuration of an automatic frequency control apparatus according to Embodiment 17 of the present invention. In FIG. 32, the description of the same reference numerals as those in Embodiment 11 is omitted.
The communication state determination unit 1708 determines whether the communication state of the mobile device is “standby reception” mainly for reception or “continuous communication” for both transmission and reception.
The reception quality measurement unit 1709 measures the reception quality of each cell, such as the reception signal level of the pilot channel and SIR (Signal to Interference Ratio).
Based on the outputs of reception quality measurement section 1709 and communication state determination section 1708, error average selection section 1710 selects the best cell frequency error from the output of error average calculation section 1103 (frequency error of each cell).
The AFC control value calculation unit 1704 calculates an AFC control value from the output of the error average selection unit 1710.

Next, the operation will be described. FIG. 33 is a flowchart showing an operation flow of frequency error selection in the automatic frequency control device of FIG.
In FIG. 32, error average calculation section 1103 calculates the frequency error of each cell (step ST3301).

  Communication state determining section 1708 determines whether the communication state of the mobile device is in standby reception or continuous communication involving transmission such as voice, data, packet communication, etc. (step ST3302).

If standby reception is in progress, communication quality measurement section 1709 measures the reception quality of each cell being received, and notifies error average selection section 1710 of the cell with the best reception quality (step ST3303). .
When the standby reception is being performed, error average selection section 1710 selects the frequency error of the cell with the best reception quality from the output of error average calculation section 1103 (step ST3305).
Then, AFC control value calculation section 1704 calculates an AFC control value (step ST3306).

On the other hand, if it is determined in step ST3302 that continuous communication is being performed, frequency errors of all received cells are selected (step ST3304).
Then, AFC control value calculation section 1704 calculates an AFC control value (step ST3306). In this case, any method of Embodiments 11 to 16 may be used as the AFC control value calculation method.

  In the prior art, it has been described that when the mobile device is moving (especially during continuous reception), the AFC follows the Doppler shift that occurs and has a great influence on the transmission signal. However, when the mobile device is in standby reception, communication is mainly received and there is no influence on the transmission signal, so it is possible to perform AFC control giving priority to reception performance. In the seventeenth embodiment, communication performance is improved by changing the control of AFC in both cases by determining whether the standby reception is being performed or during continuous reception.

As described above, according to the seventeenth embodiment, the communication state of the mobile device is determined, AFC is performed with priority on reception performance during standby reception, and continuous communication involving transmission of voice, data, packet communication, and the like is being performed. In this case, it is possible to improve the communication performance of the mobile communication system by performing stable AFC control that hardly follows the Doppler shift.
In the seventeenth embodiment, the frequency error of the cell with the best reception quality is used, but the frequency error of the path with the best reception quality can also be used.

  101 pilot channel despreading unit, 102 frequency error calculation unit, 103 error average calculation unit, 104 AFC control value calculation unit, 105 TCXO control unit, 106 speed detection unit, 107 comparator, 201 Doppler shift detection unit, 207 comparator, 304 AFC control value calculation unit, 307 comparator, 404 AFC control value calculation unit, 504 AFC control value calculation unit, 603 error average calculation unit, 604 AFC control value calculation unit, 704 AFC control value calculation unit, 709 Radio Link addition / Deletion determination unit, 803 error average calculation unit, 804 AFC control value calculation unit, 904 AFC control value calculation unit, 906 frequency error storage unit, 907 comparator, 1003 error average calculation unit, 1004 AFC control value calculation unit, 1102 frequency error Calculation unit, 1103 error average calculation unit, 1 104 AFC control value calculation unit, 1204 AFC control value calculation unit, 1304 AFC control value calculation unit, 1402 frequency error calculation unit, 1704 AFC control value calculation unit, 1708 communication state determination unit, 1709 reception quality measurement unit, 1710 error average selection Part, 9201 base station, 9202 mobile station.

Claims (6)

An error average calculating unit that calculates a frequency error for each cell or path averaged for a certain period of time;
An AFC control value calculation unit that calculates an AFC error by averaging frequency errors for each cell or each path, and calculates an AFC control value based on the AFC error ;
A reception quality measuring unit that measures reception quality for each cell or each path, and specifies a cell or path having good reception quality;
An error average selection unit that selects a frequency error of the cell or the path specified by the reception quality measurement unit;
A communication state determination unit that determines whether the mobile device is in standby reception or continuous communication, and
The automatic AFC control value calculation unit calculates an AFC control value using the frequency error selected by the error average selection unit when the state of the mobile device is waiting and being received. Frequency control device.   2. The automatic frequency control apparatus according to claim 1, wherein the AFC control value calculation unit calculates an error of the AFC using a maximum value and a minimum value in a frequency error for each cell or for each path.   The error average calculation unit detects a frequency error for each cell or each path a plurality of times for a predetermined time, and the AFC control value calculation unit calculates a maximum value and a minimum value among all frequency errors within the predetermined time. The automatic frequency control apparatus according to claim 2, wherein the error of the AFC is calculated by using the AFC.   4. The automatic frequency control apparatus according to claim 2, wherein the AFC control value calculation unit calculates the error of the AFC by averaging the maximum value and the minimum value.   5. The automatic frequency control apparatus according to claim 4, wherein the maximum value and the minimum value are averaged using a weighted average.   4. The automatic frequency control device according to claim 2, wherein the AFC control value calculation unit calculates a maximum Doppler frequency by dividing a difference between the maximum value and the minimum value by an integer 2. .

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