CN100502249C - Receiver and automatic frequency control method - Google Patents

Abstract

A searcher 105 creates a delay profile of a known symbol portion of a received base band signal by using a basic code, and a number-of-codes/kind-of-code determining unit 106 determines the number and kind of shift codes being used, on the basis of the delay profile. Correlators 108-1 to 108-n compute the correlation values between the known symbol first half of the received base band signal and the shift code. Correlators 109-1 to 109-n compute the correlation values between the known symbol second half of the received base band signal and the shift codes. A phase estimation unit 119 estimates the phase rotation per unit time by using the sum of the output signals of the correlators 108-1 to 108-n and the sum of the output signals of the correlators 109-1 to 109-n. As a result, the influence of the cross-correlation of spreading codes and the influence of noises are suppressed, so that the phase rotation between the known symbols can be estimated highly precisely to realize highly precise AFC.

Description

Receiving device and automatic frequency control method

technical field

The invention relates to a receiving device and an automatic frequency control method for a CDMA wireless communication system.

Background technique

In recent years, wireless communication systems such as mobile phones and automobile phones have spread rapidly. In a communication terminal device of a wireless communication system, a receiving device performs automatic frequency control (Automatic Frequency Control; hereinafter referred to as "AFC") to compensate for a carrier frequency deviation from that of a transmitting device.

Hereinafter, a conventional receiving device will be described with reference to FIG. 1 and FIG. 2 . FIG. 1 is a diagram showing a slot structure of data transmitted by a transmission device. Fig. 2 is a block diagram showing the configuration of a conventional receiving device.

As shown in FIG. 1 , a signal sent by a sending device (not shown) includes a known symbol 11 and a known symbol 12 spread by CodeA and CodeB respectively. Wherein, the code lengths of CodeA and CodeB are tCA and tCB respectively, and the interval between the known symbol 11 and the known symbol 12 is tgap.

The signal transmitted by the transmitting device is received by the receiving device as shown in FIG. 2 via the antenna 21 . In FIG. 2 , the frequency of the signal (received signal) received via the antenna 21 is converted from the carrier frequency to the baseband in the receiving RF section 22 . At this time, a local signal output from an oscillator 38 to be described later is used in the receiving RF unit 22 . The in-phase component (I-ch) and the quadrature component (Q-ch) of the baseband signal (reception baseband signal) output from the receiving RF section 22 are converted into digital signals by the A/D converter 23 and the A/D converter 24, respectively. , and output to the retriever 25, the correlator 26, the correlator 27 and the correlator 28.

The search unit 25 obtains the correlation between the received baseband signal converted into a digital signal and the known code CodeA, and detects the time tA when the power of the correlation value exceeds the threshold (that is, the reception time of CodeA). Also, the retrieval unit 25 calculates the reception time tB of CodeB from tA+tgap, and the retrieval unit 25 calculates the reception time tData at the head of the data part from tA+tCA/2.

The search unit 25 outputs the reception time of the head of the data part to the correlator 26 and the synchronous detection unit 29 , outputs the reception time of Code A to the correlator 27 , and outputs the reception time of Code B to the correlator 28 .

The correlator 26 obtains a correlation between the data portion of the received baseband signal and the designated spreading code (spreading code assigned to the receiving apparatus) based on the reception time at the head of the data portion input from the searcher 25 . The data part of the received baseband signal after the correlation processing is output to the synchronous detection part 29 .

The correlator 27 obtains the correlation between the known symbol 11 of the received baseband signal and CodeA according to the receiving time of CodeA input from the searcher 25 . Similarly, the correlation between the known symbol 12 of the received baseband signal and the CodeB is obtained in the correlator 28 according to the receiving time of the CodeB input from the retriever 25 .

The coherent detection section 29 performs coherent detection processing on the data section of the received baseband signal after the correlation processing based on the reception time at the head of the data section input from the searcher 25 . The data portion of the received baseband signal after synchronous detection is demodulated by the demodulation unit 30 to extract received data.

The in-phase component of the known symbol 11 of the received baseband signal after correlation processing is delayed by the delay unit 31 by tAB (=tCA/2+tgap+tCB/2; refer to FIG. 1 ), and then output to the complex correlation calculation unit 33 . Similarly, the quadrature component of the known symbol 11 of the received baseband signal after correlation processing is delayed by the delay unit 32 by tAB (=tCA/2+tgap+tCB/2), and then output to the complex correlation calculation unit 33 . The in-phase component and the quadrature component of the known symbol 12 of the received baseband signal after the correlation processing are respectively output to the complex correlation computing unit 33 .

The complex correlation calculation unit 33 performs complex correlation processing using the in-phase components of the known symbol 11 and the known symbol 12 of the received baseband signal after the correlation processing. In addition, complex correlation processing is performed in the complex correlation computing unit 33 using the quadrature components of the known symbol 11 and the known symbol 12 of the received baseband signal after the correlation processing. The in-phase component and quadrature component of the received baseband signal after the complex correlation processing are output to the phase estimation unit 34 .

The phase estimating unit 34 estimates the amount of phase rotation per unit time using the in-phase component and the quadrature component of the received baseband signal after complex correlation processing output from the complex correlation calculating unit 33 . The smoothing unit 35 calculates the frequency offset amount based on the phase rotation amount estimated by the phase estimation unit 34 . The calculated frequency shift amount is output to the control voltage conversion unit 36 .

The control voltage conversion unit 36 converts the calculated frequency offset into a signal having a predetermined control voltage to be applied to the oscillator 38 . The signal output from the control voltage conversion unit 36 is converted into an analog signal by a D/A converter 37 and output to an oscillator 38 . Thus, the frequency of the local signal in oscillator 38 is controlled to compensate for the frequency offset.

In this way, the above-mentioned conventional receiving apparatus estimates the amount of phase rotation between known symbols in the received signal to calculate the amount of frequency offset, and then performs AFC to compensate for the amount of frequency offset.

However, since the correlated known symbols are affected by the cross-correlation of spreading codes and the influence of interference, etc., it is difficult for the above-mentioned conventional receiving apparatus to estimate the phase rotation amount between known symbols with high precision, and there is an AFC Accuracy deterioration problem.

Contents of the invention

The object of the present invention is to provide a receiving device and an automatic frequency control method capable of suppressing the influence of cross-correlation of spreading codes and the influence of interference and estimating the amount of phase rotation between known symbols with high precision to achieve high precision. The AFC.

The transmitter inserts known symbols composed of spreading codes obtained by code shifting into the transmission data and performs multiplexed transmission, and the receiver estimates the amount of phase rotation using a value obtained by adding correlation values of a plurality of known symbols , so that the purpose of the present invention can be achieved.

The receiving device of the present invention includes: a retrieval unit for calculating a first correlation value, that is, a correlation value between a received signal of a known symbol formed by a part of a specified basic code and said basic code; a judging unit for calculating a first correlation value according to said first A correlation value exceeds the number of the specified threshold and the time zone to which the receiving moment belongs, and judges the number and type of known symbols multiplexed through time; the correlation value calculation part calculates the second correlation value, that is, inserts the known symbols The first half of the received signal part and the correlation value of the known symbol judged to be time-multiplexed by the judging part, and calculate the third correlation value, that is, the second half of the known symbol and the judged already the correlation value of the known symbol; the phase rotation amount estimating section estimates the phase rotation amount based on the phase difference between the addition result of the second correlation value and the addition result of the third correlation value; and the frequency control section estimates the phase rotation amount based on the addition result of the third correlation value; The frequency of the oscillator is controlled by the amount of phase rotation described above to compensate for the frequency offset.

The present invention provides a communication terminal device provided with a receiving device, the receiving device includes: a retrieval unit that calculates a first correlation value, that is, inserts a received signal of a known symbol constituted by a part of a specified basic code with the described The correlation value of the basic code; the judging part, according to the number of the first correlation value exceeding the specified threshold and the time zone to which the receiving moment belongs, judges the number and type of known symbols multiplexed through time; the correlation value calculation part calculates The second correlation value, that is, the correlation value between the received signal portion inserted into the first half of the known symbol and the known symbol judged to be time-multiplexed by the judging part, and calculate the third correlation value, that is, the a correlation value between the second half of the known symbol and the judged known symbol; the phase rotation amount estimating unit, based on the phase difference between the addition result of the second correlation value and the addition result of the third correlation value to estimate the amount of phase rotation; and a frequency control part for controlling the frequency of the oscillator according to the amount of phase rotation to compensate for the frequency offset.

The present invention provides a base station device provided with a receiving device, the receiving device includes: a retrieval unit that calculates a first correlation value, that is, inserts a received signal of a known symbol constituted by a part of a specified basic code with the basic code The correlation value of the code; the judging part, according to the number of the first correlation value exceeding the specified threshold and the time zone to which the receiving moment belongs, judges the quantity and type of the known symbols multiplexed through time; the correlation value calculation part calculates the second Two correlation values, that is, the correlation value between the received signal part inserted into the first half of the known symbol and the known symbol judged to be time-multiplexed by the judging part, and the third correlation value is calculated, that is, the already The second half of the known symbol and the correlation value of the judged known symbol; the phase rotation amount estimation part is based on the phase difference between the addition result of the second correlation value and the addition result of the third correlation value estimating an amount of phase rotation; and frequency control means for controlling the frequency of the oscillator based on the amount of phase rotation to compensate for the amount of frequency offset.

The automatic frequency control method of the present invention includes the following steps: calculating the first correlation value, that is, inserting the correlation value between the received signal of the known symbol formed by a part of the specified basic code and the basic code; according to the first A correlation value exceeds the number of the specified threshold and the time zone to which the receiving moment belongs, judging the quantity and type of known symbols multiplexed through time; calculating the second correlation value, that is, inserting the received signal part of the first half of the known symbol and judging as the correlation value of the time-multiplexed known symbol, and calculating a third correlation value, that is, a correlation value between the second half of the known symbol and the judged known symbol; according to the second A phase difference between the addition result of the correlation value and the addition result of the third correlation value is used to estimate the amount of phase rotation; and the frequency of the oscillator is controlled according to the amount of phase rotation to compensate for the frequency offset.

The automatic frequency control method of the present invention includes the following steps: calculating the first correlation value, that is, inserting the correlation value between the received signal of the known symbol formed by a part of the specified basic code and the basic code; according to the first A correlation value exceeds the quantity of the specified threshold and the time zone to which the receiving moment belongs, and judges the quantity, type and time of correlation processing of the known symbols multiplexed through time; according to the quantity, type and correlation of the known symbols calculating the correlation value of the time-multiplexed one or more received signals; estimating the phase rotation amount using the summed value of the correlation value; and controlling the frequency of the oscillator according to the phase rotation amount to compensate the frequency Offset.

Description of drawings

FIG. 1 is a diagram representing a time slot structure of data transmitted by a transmitting device;

FIG. 2 is a block diagram showing the structure of a conventional receiving device;

FIG. 3 is a diagram illustrating a method of generating a spreading code for a known symbol portion of the present invention;

4 is a time slot structure diagram of data sent by a base station device performing wireless communication with a communication terminal device according to Embodiment 1 of the present invention;

Fig. 5 is a block diagram showing the structure of the communication terminal device related to the above-mentioned embodiment;

FIG. 6 is a diagram showing a delay distribution made in the communication terminal device according to the above-mentioned embodiment;

FIG. 7A is a diagram showing an estimated phase rotation amount in the communication terminal apparatus related to the above-mentioned embodiment;

FIG. 7B is a diagram showing the phase rotation amount estimated in the communication terminal apparatus related to the above-mentioned embodiment;

FIG. 7C is a diagram showing the phase rotation amount estimated in the communication terminal apparatus related to the above-mentioned embodiment; and,

Fig. 8 is a block diagram showing the configuration of a communication terminal device according to Embodiment 2 of the present invention.

Detailed ways

Before starting to describe the various embodiments, firstly, taking FIG. 3 as an example, the method for generating the spreading code for inserting the known symbols of the transmitted data by the sender in the present invention will be described.

In FIG. 3, the length of the basic code is P (chip), and the maximum delay distribution length of the wireless line is W (chip). Moreover, two identical basic codes are connected in series, the front is the basic code BC1, and the rear is the basic code BC2.

The spreading code Code1 corresponding to user 1 is made by adding W from the beginning of the basic code BC2 to the basic code BC1. The spreading code Code2 corresponding to user 2 is made by removing the W portion from the head of the basic code BC1 and adding 2×W from the head of the basic code BC2. That is, the spread code Code2 is obtained by shifting (Shift) W the part corresponding to the basic code Code1 in the basic codes BC1 and BC2 to the rear.

Similarly, if the number of users is K, the spreading code Codei corresponding to user i (i=1, 2, ..., K) is obtained by removing (i-1)×W part from the front of the basic code BC1 It is made by adding the part of i×W from the front of the basic code BC2 again. The length of each spreading code Codei is Lm=P+W (chips).

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In addition, in the following description, the transmitting side is a base station device, and the receiving side is a communication terminal device. In addition, in the following description, the spreading code generated by the method shown in FIG. 3 is referred to as a "shift code" without taking delay waves into consideration.

Example 1

FIG. 4 is a diagram showing a time slot structure of data transmitted from a base station device performing wireless communication with a communication terminal device according to Embodiment 1 of the present invention. As shown in Figure 4, the known symbols are inserted into the slightly central portion of the time slot. The known symbol is the spreading code generated by the method shown in FIG. 3 . In addition, the data portion is multiplied by a spreading code unique to each user.

The base station apparatus multiplexes and transmits a signal having a slot structure as shown in FIG. 4 to each communication terminal apparatus (user) in communication. Furthermore, the basic code and the shift amount are notified in advance to each communication terminal device by transmission and reception of a control signal.

FIG. 5 is a block diagram showing the configuration of a communication terminal device according to this embodiment. In addition, FIG. 5 shows the configuration of the receiving side in the communication terminal device, and the configuration of the sending side is omitted.

The receiving antenna 101 receives radio signals transmitted from the base station apparatus. The receiving RF unit 102 multiplies a signal received by the receiving antenna 101 by a local signal oscillated by an oscillator 123 described later, and converts the frequency of the received signal into baseband.

The A/D converter 103 performs A/D conversion on the in-phase component (I-ch) of the baseband signal (hereinafter referred to as “reception baseband signal”) output from the reception RF unit 102 . Similarly, the A/D converter 104 performs A/D conversion on the quadrature component (Q-ch) of the received baseband signal.

The retriever 105 uses the basic code shown in FIG. 3 above to make the delay profile of the known symbol in the received baseband signal converted into a digital signal, and detects the time when the correlation value power exceeds the threshold (that is, the receiving time of the known symbol ), and output to the number of codes-kind judgment section 106. In addition, the search unit 105 calculates the reception time at the head of the data part from the reception time of the known symbol, and outputs it to the correlator 107 and the coherent detection unit 110 .

The number of codes-type judging section 106 judges the quantity and the kind of the shift codes in use now according to the receiving time of the known symbols sent by the retriever 105, and correlators 108-1 to n and correlators 109-1 to n (n is a natural number greater than 2) issue instructions related to processing time. The details of the judgment of the code number and its type by the code number-type judging unit 106 will be described later.

The correlator 107 obtains the correlation between the data portion of the received baseband signal and the specified spreading code (spreading code assigned to the own device) according to the reception time at the head of the data portion output by the searcher 105, and correlates the received data portion after the correlation processing. The data part of the baseband signal is output to the synchronous detection part 110 .

The correlators 108-1 to n respectively calculate the correlation value (hereinafter referred to as "symbol first half correlation value") of the known symbol first half of the received baseband signal and the shift code according to the instruction of the code number-type determination unit 106 . Similarly, the correlators 109-1 to n respectively calculate the correlation values of the known symbol second half of the received baseband signal and the shift code (hereinafter referred to as "symbol second half correlation value").

The coherent detection unit 110 performs coherent detection processing on the data unit of the received baseband signal after the correlation processing based on the reception time at the head of the data unit output by the searcher 105 , and outputs it to the demodulation unit 111 . The demodulation unit 111 demodulates the received baseband signal after coherent detection, and extracts received data.

The adder 112 adds the in-phase components of the correlation values in the first half of the symbol calculated by the correlators 108-1 to n, respectively. Likewise, the adder 113 adds the quadrature components of the correlation values in the first half of the symbol calculated by the correlators 108-1 to n, respectively.

The adder 114 adds the in-phase components of the correlation values in the second half of the symbol calculated by the correlators 109-1 to n, respectively. Similarly, the adder 115 adds the quadrature components of the correlation values in the second half of the symbol calculated by the correlators 109-1 to n, respectively.

The delay unit 116 delays the in-phase component of the correlation value of the first half of the symbol added by the adder 112 by a predetermined amount, and then outputs it to the complex correlation calculation unit 118 . Similarly, the delay unit 117 delays the quadrature component of the correlation value of the first half of the symbol added by the adder 113 by a predetermined amount, and then outputs it to the complex correlation operation unit 118 .

The complex correlation calculation unit 118 performs complex correlation processing using the added in-phase component of the first half of the symbol correlation value and the added in-phase component of the second half of the symbol correlation value. In addition, the complex correlation calculation unit 118 performs complex correlation processing using the added quadrature component of the first half of the symbol correlation value and the added quadrature component of the second half of the symbol correlation value.

The phase estimation unit 119 estimates the amount of phase rotation per unit time using the in-phase component and the quadrature component of the correlation value after the complex correlation processing output by the complex correlation calculation unit 118 . The details of the estimation of the phase rotation amount by the phase estimation unit 119 will be described later.

The smoothing unit 120 smoothes the phase rotation amount estimated by the phase estimation unit 119 to calculate the frequency offset amount. The control voltage conversion unit 121 converts the calculated frequency offset into a signal having a prescribed control voltage to be applied to the oscillator 123 and outputs it to the D/A converter 122 . The D/A converter 122 converts the signal output from the control voltage conversion unit 121 into an analog signal. The oscillator 123 outputs a local signal whose frequency corresponds to the voltage of the signal output from the D/A converter 122 .

Next, an implementation procedure of AFC in the communication terminal device shown in FIG. 3 will be described.

The radio signal transmitted from the base station is received by the receiving antenna 101, multiplied by the receiving RF unit 102 by the local signal output from the oscillator 123, and then converted into a baseband frequency.

The in-phase component of the received baseband signal is converted into a digital signal at the A/D converter 103 , and the quadrature component of the received baseband signal is converted into a digital signal at the A/D converter 104 . The reception baseband signal converted into a digital signal is output to the searcher 105, the correlator 107, the correlators 108-1 to n and the correlators 109-1 to n.

The search unit 105 makes the delay profile of the known symbol portion of the received baseband signal converted into a digital signal based on the basic code shown in FIG. The number and types of shift codes currently in use are used to make a judgment.

The correlator 107 obtains the correlation between the data part of the received baseband signal and the specified spreading code (spreading code assigned to the own device) based on the reception time at the head of the data part, and the coherent detection part 110 obtains the correlation between the data part received at the head of the data part. The coherent detection process is performed on the data part of the received baseband signal after the correlation processing at all times, and the demodulation part 111 demodulates the data part of the received baseband signal after the coherent detection to extract the received data.

In addition, the correlators 108-1 to n calculate the correlation value of the first half of the symbol according to the known first half of the symbol and the shift code of the received baseband signal respectively. Similarly, the correlators 109-1 to n respectively calculate the correlation value of the second half of the symbol according to the known second half of the symbol and the shift code of the received baseband signal.

The adders 112, 113 add the in-phase component and the quadrature component of the correlation values of the first half of the symbol calculated by the correlators 108-1 to n, respectively. Delay units 116, 117 delay it by a specified amount. The adders 114, 115 add the in-phase component and the quadrature component of the correlation values in the second half of the symbol calculated by the correlators 109-1 to n, respectively.

The complex correlation calculation unit 118 calculates the in-phase component of the correlation value in the first half of the symbol after the addition and the in-phase component of the correlation value in the second half of the symbol after the addition, and the quadrature component and the phase of the correlation value in the first half of the symbol after the addition. The quadrature component of the correlation value of the second half of the added symbol is used for complex correlation processing.

The phase estimation unit 119 estimates the amount of phase rotation per unit time from the in-phase component and the quadrature component of the correlation value after the complex correlation processing. The smoothing unit 120 smoothes the amount of phase rotation to calculate a frequency offset, and the calculated frequency offset is output to the control voltage conversion unit 121 .

The control voltage conversion unit 121 converts the calculated frequency offset into a signal having a predetermined control voltage, and the signal is converted into an analog signal by the D/A converter 122 and output to the oscillator 123 . The oscillator 123 outputs a local signal whose frequency corresponds to the voltage of the signal output from the D/A converter 122 .

Next, the method of judging the code number and its type by the code number-type judgment unit 106 will be described in detail using FIG. 6 showing the delay distribution. FIG. 6 is a diagram showing a delay profile created in the communication terminal device according to this embodiment. In FIG. 6, the horizontal axis represents time, and the vertical axis represents power.

When the base station device multiplexes and transmits the data shown in FIG. 4 above to multiple communication terminal devices, once the receiver of the communication terminal device uses the basic code to make the delay distribution of the known symbols in the received baseband signal, it can detect that the data exceeds the threshold. The number of peaks is equivalent to the number of communication terminal devices that are currently communicating.

If the base station device uses the shift code Codei to perform wireless communication with the communication terminal device, the time when the base station device sends data is 0, and the time range Ti from time (i-1)×W to less than time i×W exceeds The peak value of the threshold will be revealed.

For example, FIG. 6 shows the peaks P1 and P3 exceeding the threshold in the range of T1 and T3, so it can be seen that the base station device uses the shift code Code1 and the shift code Code3 to perform wireless communication with the communication terminal device.

The code number-type judging section 106 judges the number of communication terminal devices currently performing wireless communication with the base station device according to the number of peak values exceeding the threshold value, and judges the shift of known symbols in the transmitted signal by the base station device according to the time zone to which the peak value belongs. code.

In FIG. 6 , the code number-type determination unit 106 instructs the correlator 108-1 to use the time P1 as the correlation processing time, and instructs the correlator 108-2 to use the time P3 as the correlation processing time. In addition, the code number-type judging unit 106 sets the length of the known symbol part as tk, gives the correlator 109-1 an instruction using the time (P1+tk/2) as the correlation processing time, and gives the correlator 109-2 An instruction with time (P3+tk/2) as the relevant processing time.

Next, the method of estimating the amount of phase rotation by the phase estimation unit 119 will be described in detail using FIGS. 7A , 7B, and 7C showing the amount of phase rotation. 7A, 7B, and 7C are diagrams showing phase rotation amounts estimated in the communication terminal apparatus according to this embodiment. In FIG. 7A, FIG. 7B, and FIG. 7C, correlation values are shown as vectors on the IQ plane.

In Fig. 7A, vector 201 is the correlation value of the first half of the known symbol of the received baseband signal and the first half of the symbol of the shift code Code1, and vector 202 is the correlation value of the first half of the known symbol of the received baseband signal and the first half of the symbol of the shift code Code3 value, vector 203 is the resultant vector of vector 201 and vector 202 added.

In Fig. 7B, vector 211 is the known symbol rear half of the received baseband signal and the symbol rear half correlation value of the shift code Code1, and vector 212 is the known symbol rear half of the received baseband signal and the symbol of the shift code Code3 The second-half correlation value, the vector 213 is a resultant vector obtained by adding the vector 211 and the vector 212 .

In FIG. 7C , the angle difference θ between the resultant vector 203 and the resultant vector 213 represents the amount of phase rotation. The phase estimation unit 119 estimates the amount of phase rotation using a value obtained by adding a plurality of known symbol correlation values.

In this way, the sender inserts the known symbols formed by the spreading codes obtained by code shifting into the sent data and performs multiplexed transmission, so that the receiver can calculate the correlation values of multiple known signals.

Here, since the cross-correlation and interference of spreading codes that affect the correlated known signal are random, by adding the correlation values of multiple known symbols, it is possible to suppress the phase rotation amount when estimating Effects by cross-correlation of spreading codes and effects by interference.

Therefore, the sender inserts known symbols composed of spreading codes obtained by code shifting into the transmitted data and performs multiplex transmission, and the receiver estimates the phase rotation by adding the correlation values of multiple known signals The amount of phase rotation between known symbols can be estimated with high precision, and high-precision AFC can be realized.

As for the number n of correlators 108-1 to n and correlators 109-1 to n, although it is ideal when it is equivalent to the number of codes that can communicate simultaneously, the present invention is under the condition that the number of each correlator is less than the number of codes is also established. At this time, the code number-type determination unit 106 sequentially selects the currently used shift codes from the one with the higher peak value, and instructs the correlators 108-1 to n and the correlators 109-1 to n the timing of the correlation processing.

Example 2

In the first embodiment above, in the case where there is only one communication terminal device currently communicating with the base station device, not only the technical feature of adding correlation values of known signals cannot be used, but also the first half of the known symbols with similar time and Estimating the amount of phase rotation in the second half may further deteriorate the estimation accuracy of the amount of phase rotation compared to the prior art.

In order to solve the above-mentioned problem, in the second embodiment, the case where the correlation value for estimating the phase rotation amount is switched according to the number of shift codes currently in use will be described.

Fig. 8 is a block diagram showing the configuration of a communication terminal device according to Embodiment 2 of the present invention. In addition, in the communication terminal device shown in FIG. 8, the same symbols are assigned to the same components as those of the communication terminal device shown in FIG. 5, and description thereof will be omitted.

In the communication terminal device shown in FIG. 8, the function of code number-type judgment unit 301 is different from the function of code number-type judgment unit 106 in the communication terminal device shown in FIG. In addition, in the communication terminal device shown in FIG. 8, correlators 302, 303 and switching unit 304 are added to the structure compared with the communication terminal device shown in FIG.

The search unit 105 detects the time when the correlation value power exceeds the threshold value (that is, the reception time of the known symbol), and outputs it to the code number-type determination unit 301 .

The code number-type determination unit 301 determines the number and type of the currently used shift codes according to the receiving time of the known symbols output by the searcher 105 . Then, when there are a plurality of shift codes currently in use, the code number-type judgment unit 301 instructs the correlators 108-1 to n and the correlators 109-1 to n (n is a natural number equal to or greater than 2) to perform correlation processing. moment. If there is only one, the correlator 302 is instructed to perform the correlation processing, and the correlator 303 is instructed to execute the correlation processing.

Furthermore, the code number-type determination unit 301 performs switch switching control on the switch unit 304 according to the number of shift codes currently in use. Specifically, when the number of shift codes currently in use is multiple, switching control is performed so that the adder 112 and the delayer 116, the adder 113 and the complex correlation operation unit 118, the adder 114 and the delayer 117, and The adder 115 and the complex correlation operation unit 118 are respectively connected. Conversely, when the number of shift codes currently in use is one, switching control is performed such that the correlator 302 and the delayer 116, the correlator 302 and the complex correlation operation section 118, the correlator 303 and the delayer 117, and the correlator 303 They are respectively connected to the complex correlation calculation unit 118 .

The correlator 302 calculates the correlation value between the entire known symbol portion of the received baseband signal and the shifted code (hereinafter referred to as the “entire symbol correlation value”) according to the instruction of the code number-type determination unit 301 .

The correlator 303 calculates the correlation value (hereinafter referred to as "control channel correlation value") between the received signal of the synchronization control channel and the spreading code of the control channel according to the instruction of the code number-type determination unit 301 .

The switching unit 304 switches connections according to the control of the code number-type judging unit 301 described above.

As a result, when the number of currently used shift codes is one, the phase estimating unit 119 estimates the amount of phase rotation based on the angle difference between the correlation value of the entire symbol and the correlation value of the control channel for synchronization.

In this way, by switching the correlation value for estimating the amount of phase rotation according to the number of shift codes currently in use, when the number of shift codes is multiple, the same effect as that of the above-mentioned embodiment 1 can be obtained. Stable AFC can be performed even when the number of is one.

Here, when all the cells use a common synchronization control channel, there is a possibility that the phase rotation amount is estimated by erroneously using the control channel of another cell, and in this case, the accuracy of introducing the frequency offset amount is greatly deteriorated. In this case, the stability of the system can be improved by estimating the amount of phase rotation using a synchronization control channel unique to each unit.

In addition, since the offset amount of the synchronization control channel at the head of the slot varies from unit to unit, the position of the synchronization control channel and the position of the known symbol part may be temporally close. In this case, as described in Embodiment 1, AFC can be performed with high accuracy by estimating the amount of phase rotation using the first half and the second half of the known symbol portion. In this way, by knowing the position of the control channel for synchronization before the line is established, the communication terminal device can appropriately switch the signal for estimating the amount of phase rotation according to the positional relationship between the control channel and the known symbol part, so that constant degree of stability of the AFC.

In addition, the above embodiments can be combined with space diversity reception and path diversity reception to achieve more stable and high-precision AFC.

Furthermore, in the above-mentioned embodiments, the situation where the sender is a base station device and the receiver is a communication terminal device has been described, but the present invention is also applicable to the case where the receiver is a base station device and the sender is a communication terminal device Down.

Furthermore, in the above-mentioned embodiments, delayed waves are not considered for simplification of description, but the present invention can obtain the above-mentioned effects even in a propagation environment where delayed waves exist if the receiving device is equipped with structural parts for performing channel estimation and RAKE synthesis.

Moreover, in each of the above-mentioned embodiments, by adding the known symbol correlation values of other time slots and performing complex correlation calculations to estimate the phase rotation amount, the influence of the cross-correlation of spreading codes and the interference caused by interference can be further suppressed. The impact of the effect, and achieve more high-precision AFC.

To sum up, through the present invention, since a plurality of known symbol correlation values can be added, the influence by the cross-correlation of the spreading code and the influence by the interference can be suppressed and the phase between the known symbols can be estimated with high precision Rotation amount, thereby realizing high-precision AFC.

This specification is based on Japanese Patent No. 2000-278193 filed on September 13, 2000, the entire contents of which are incorporated herein.

Industrial availability

The present invention is applicable to a communication terminal device or a base station in a CDMA wireless communication system.

Claims (8)

1, a kind of receiving system comprises: searching part, calculate first correlation, that is and, insert by the received signal of the known symbol that a part constituted of specifying basic code and the correlation of described basic code;

Decision means, the quantity and the time under the time of reception thereof that surpass assign thresholds according to described first correlation are with, and judge the quantity and the kind of the known symbol that the elapsed time is multiplexing;

The correlation value calculation parts, calculate second correlation, promptly, insert the received signal part and the correlation that is judged as multiplexing known symbol of elapsed time in described decision means of described known symbol first half, and calculating third phase pass value, that is the correlation of the latter half of and described known symbol of described known symbol, through judging;

The amount of phase rotation estimation section is estimated the amount of phase rotation according to the phase difference of the addition result of the addition result of described second correlation and described third phase pass value; And

Frequency control part, according to the frequency of described the amount of phase rotation control generator with the compensating frequency side-play amount.

2, receiving system as claimed in claim 1, wherein: the correlation value calculation parts, calculate the 4th correlation, promptly, insert the received signal part and the correlation that is judged as in decision means through time-multiplexed known symbol of known symbol, and, the 5th correlation calculated, that is the correlation of the spreading code of received signal and control channel; The amount of phase rotation estimation section then when when the quantity of time-multiplexed known symbol is one, is estimated the amount of phase rotation according to the phase difference of described the 4th correlation and described the 5th correlation.

3, receiving system as claimed in claim 2, wherein, the correlation value calculation parts use the distinctive control channel in unit to calculate the 5th correlation.

4, receiving system as claimed in claim 2, wherein, even the amount of phase rotation estimation section is when the quantity through time-multiplexed known symbol is one, when control channel is close in time with known symbol, then estimate the amount of phase rotation according to the phase difference of described second correlation and described third phase pass value.

5, a kind of communication terminal that is provided with receiving system, described receiving system comprises: searching part, calculate first correlation, that is, insert by the received signal of the known symbol that a part constituted of specifying basic code and the correlation of described basic code;

Decision means, the quantity and the time under the time of reception thereof that surpass assign thresholds according to described first correlation are with, and judge the quantity and the kind of the known symbol that the elapsed time is multiplexing;

The correlation value calculation parts, calculate second correlation, promptly, insert the received signal part and the correlation that is judged as multiplexing known symbol of elapsed time in described decision means of described known symbol first half, and calculating third phase pass value, that is the correlation of the latter half of and described known symbol of described known symbol, through judging;

The amount of phase rotation estimation section is estimated the amount of phase rotation according to the phase difference of the addition result of the addition result of described second correlation and described third phase pass value; And

Frequency control part, according to the frequency of described the amount of phase rotation control generator with the compensating frequency side-play amount.

6, a kind of base station apparatus that is provided with receiving system, described receiving system comprises: searching part, calculate first correlation, that is, insert by the received signal of the known symbol that a part constituted of specifying basic code and the correlation of described basic code;

Decision means, the quantity and the time under the time of reception thereof that surpass assign thresholds according to described first correlation are with, and judge the quantity and the kind of the known symbol that the elapsed time is multiplexing;

The correlation value calculation parts, calculate second correlation, promptly, insert the received signal part and the correlation that is judged as multiplexing known symbol of elapsed time in described decision means of described known symbol first half, and calculating third phase pass value, that is the correlation of the latter half of and described known symbol of described known symbol, through judging;

The amount of phase rotation estimation section is estimated the amount of phase rotation according to the phase difference of the addition result of the addition result of described second correlation and described third phase pass value; And

Frequency control part, according to the frequency of described the amount of phase rotation control generator with the compensating frequency side-play amount.

7, a kind of auto frequency control method comprises the steps: to calculate first correlation, that is, insert by the received signal of the known symbol that a part constituted of specifying basic code and the correlation of described basic code; The quantity and the time under the time of reception thereof that surpass assign thresholds according to described first correlation are with, and judge quantity and kind through time-multiplexed known symbol; Calculate second correlation, that is, insert the received signal part and the correlation that is judged as through time-multiplexed known symbol of known symbol first half, and, calculate third phase pass value, that is, and the correlation of the latter half of and described known symbol of described known symbol through judging; Phase difference according to the addition result of the addition result of described second correlation and described third phase pass value is estimated the amount of phase rotation; And according to the frequency of described the amount of phase rotation control generator with the compensating frequency side-play amount.

8. an auto frequency control method comprises the steps:

Calculate first correlation, that is, insert by the received signal of the known symbol that a part constituted of specifying basic code and the correlation of described basic code;

The quantity and the time under the time of reception thereof that surpass assign thresholds according to described first correlation are with, and judge the moment of quantity, kind and the relevant treatment of the known symbol that the elapsed time is multiplexing;

Calculate correlation according to the moment of quantity, kind and the relevant treatment of the known symbol of described judgement through time-multiplexed one or more received signals;

Use the additive value of described correlation to estimate the amount of phase rotation; And

According to the frequency of described the amount of phase rotation control generator with the compensating frequency side-play amount.

Images