JP3819874B2 - Path search device, communication terminal device, and path search method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication terminal device such as a mobile phone terminal that employs a direct spread spectrum communication system, and a path search device and a path search method for determining a useful multipath applied to such a communication terminal device, for example.
[0002]
[Prior art]
The DS-CDMA (Direct Sequence-Code Division Multiple Access) communication system is a system in which a plurality of receivers communicate at the same frequency using different spreading codes. In mobile communication, a multi-wave propagation path (multipath) is formed due to the influence of buildings and topography between a base station and a receiver. In the DS-CDMA system, reception quality can be improved by separating these multiplexed waves and combining them with RAKE.
[0003]
Specifically, the receiver periodically generates a delay profile by using a path search finger. In general, the delay profile is calculated by calculating the correlation power value between a known pilot signal included in the received signal and the spreading code (scramble code) by slightly shifting the delay time of the spreading code. Generated as data containing values. Correlation power values corresponding to the number of RAKE fingers are selected from the delay profiles in descending order, and delay times corresponding to these correlation power values are assigned to RAKE fingers as useful path phases. Assigning the phase of the spreading code to the RAKE finger in this way is called path assignment.
[0004]
The RAKE finger despreads the received signal using the spreading code having the phase assigned as described above. For this despreading, the RAKE finger also calculates a correlation power value between the spreading code and the received signal. The signal despread by each RAKE finger is RAKE synthesized by the RAKE synthesizer.
[0005]
In mobile communications, each path of a multiwave propagation path undergoes Rayleigh fluctuation. For this reason, when a delay profile is generated by the path search finger, a large correlation power value may be temporarily obtained or a small correlation power value may be obtained due to the influence of the fluctuation of the multi-wave propagation path. is there. In this case, a path with a large correlation power value is not originally assigned to the RAKE finger, and conversely, a path with a originally low correlation power value may be erroneously assigned to the RAKE finger. In this case, reception characteristics are deteriorated.
[0006]
On the other hand, since the path assigned to the RAKE finger is updated according to the content of the generated delay profile, if the content of the delay profile changes significantly, all the paths assigned to the RAKE finger may be replaced. . When the allocation path to the RAKE finger is changed, the phase of the code for despreading must be matched with the phase of the new path, so that the processing at the receiver increases and the power consumption may increase. .
[0007]
As a technique for solving such a problem, a state weighting function is calculated by averaging path fluctuations due to fading or the like with respect to a delay profile, and by assigning current paths to a plurality of RAKE fingers. It is known to perform a path search after multiplying a delay profile by a weighting function (see, for example, Patent Document 1).
[0008]
However, the averaging of path fluctuations due to fading is expected to have a certain degree of stabilization effect against instantaneous frequency fluctuations, but it is necessary to deal with the instantaneous decrease in received power due to shadowing etc. I can't. Also, in the method of multiplying the delay profile by the state weighting variable calculated based on the current path assignment state of the conventional RAKE finger, the currently assigned path is unconditionally set to a superior level. There is a risk that adaptability to changes in the communication state may be reduced.
[0009]
On the other hand, in order to cope with fading fluctuation, the correlation power value included in the delay profile obtained by the path search finger and the correlation power value obtained by the RAKE finger are combined to determine a path to be assigned to the RAKE finger. A technique for obtaining information is known (see, for example, Non-Patent Document 1). This technique shows that the delay profile is weighted according to the reliability of each information when the delay profile and the correlation power value obtained by the RAKE finger are combined.
[0010]
[Patent Document 1]
JP 2000-115022 JP
[0011]
[Non-Patent Document 1]
IEEE PIMRC2002, "Path-Search Algorithm Introducing Path-Management Tables for a DS-CDMA Mobile Terminal", Mitsugi et.al., Sept. 2002
[0012]
[Problems to be solved by the invention]
However, in general, in mobile communication, the moving speed of a user and the moving speed of surrounding obstacles change with time, so the weighting factor defined for the above weighting is not an optimal value in some cases, and the communication quality is reduced. May decrease.
[0013]
The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a path that can determine a useful path so that a stable reception operation can be ensured by adapting to changes in the environment. A search device, a communication terminal device, and a path search method are provided.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a multiwave signal including a plurality of direct spread spectrum signals received via a multipath and a phase corresponding to a path useful for RAKE combining among the multipaths. The first instantaneous correlation power value with the spreading code of the first is periodically calculated by a plurality of calculation means, and the first instantaneous correlation power value is weighted and averaged periodically according to the first coefficient, respectively. An average correlation power value is obtained, a second instantaneous correlation power value of each of the multiple wave signals and spread codes having a number of phases larger than the number of the calculation means is periodically calculated, and the second instantaneous correlation power value is calculated. Each of the first average correlation power value and the second average correlation power value are obtained by performing weighted averaging periodically according to the second coefficient, and spreading the first average correlation power value and the second average correlation power value in the same phase. The number corresponding to the sign A third average correlation power value is obtained by periodically synthesizing with a weight corresponding to a coefficient, the useful path is determined based on the third average correlation power value, and the first coefficient and the second coefficient At least one of the coefficient and the third coefficient is changed according to the fluctuation speed of the multipath or according to the error rate of the data obtained by RAKE combining the useful multipath.
[0015]
By adopting such means, a multi-wave signal including a plurality of direct spread spectrum signals received via a multi-path and a phase spread corresponding to a path useful for RAKE combining among the multi-paths. The first instantaneous correlation power value with the code is periodically calculated by a plurality of calculation means, and the first instantaneous correlation power value is periodically weighted and averaged according to the first coefficient, respectively. A correlation power value is obtained. On the other hand, the second instantaneous correlation power value between the multi-wave signal and each of the spread codes having a number of phases larger than the number of calculation means is periodically calculated, and the second instantaneous correlation power value is calculated according to the second coefficient. A second average correlation power value is obtained by periodically performing weighted averaging. Then, the first average correlation power value and the second average correlation power value are periodically combined with the weight corresponding to the third coefficient between the ones corresponding to the spreading codes of the same phase, thereby obtaining the third average correlation power value. A value is determined and a useful path is determined based on the third average correlation power value. At this time, at least one of the first coefficient, the second coefficient, and the third coefficient is changed in accordance with the fluctuation speed of the multipath or in accordance with the error rate of the data obtained by RAKE combining for the useful multipath. The Therefore, the weight when averaging the first instantaneous correlation power value, the weight when averaging the second instantaneous correlation power value, or the first average correlation power value and the second average correlation power value are combined. The weighting is adaptively adjusted according to the multipath fluctuation speed and error rate.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of a communication terminal apparatus for direct spread spectrum communication according to the first embodiment.
As shown in FIG. 1, the communication terminal apparatus according to the first embodiment includes an antenna 1, a radio frequency unit (hereinafter referred to as an RF unit) 2, a RAKE receiving unit 3, and a multipath search unit 4.
[0017]
The direct spread spectrum signal received by the antenna 1 is input to the RF unit 2. The RF unit 2 down-converts the direct spread spectrum signal into a baseband signal. The RF unit 2 further samples the down-converted signal and converts it into a digital signal. The output signal of the RF unit 2 is input to the RAKE receiving unit 3 and the multipath search unit 4.
[0018]
The RAKE receiving unit 3 includes a plurality of RAKE fingers 31 and a RAKE combining unit 32. Each of the RAKE fingers 31 includes a transmission path estimation unit 31b and a despreading unit 31a.
[0019]
The output signal of the RF unit 2 is input to the despreading unit 31a and the transmission path estimation unit 31b of each RAKE finger 31, respectively. The despreading unit 31a despreads the input signal using a spread code having a phase corresponding to the path assigned by the multipath search unit 4. The transmission path estimation unit 31b performs transmission path response estimation. The transmission path estimation unit 31b outputs the result of the transmission path response estimation to the despreading unit 31a. The transmission path estimation unit 31b further calculates a correlation power value between the input signal and the spread code having the phase corresponding to the assigned path. The correlation power value obtained by the transmission path estimation unit 31b is output to the multipath search unit 4 as an instantaneous correlation power value. The RAKE combining unit 32 performs RAKE combining of outputs from the despreading unit 31a of each RAKE finger 31.
[0020]
The multipath search unit 4 further includes a fluctuation speed estimation unit 40, a coefficient setting unit 41, a searcher 42, a first update unit 43, a first table 44, a second update unit 45, a second table 46, a third update unit 47, A third table 48 and a path allocation unit 49 are included.
[0021]
The fluctuation speed estimation unit 40 estimates the fluctuation speed of the direct spread spectrum signal transmission path based on the output signal of the RF unit 2. The coefficient setting unit 41 sets the values of the coefficients α, β, and γ based on the fluctuation speed estimated by the fluctuation speed estimation unit 40. The coefficient setting unit 41 outputs the coefficient α to the first update unit 43, the coefficient β to the second update unit 45, and the coefficient γ to the third update unit 47. The coefficient α and the coefficient β define the average length of the observation path and are related to the path switching frequency. The coefficient γ defines the specific gravity of weighting based on the actual reception state at the RAKE finger 31.
[0022]
The searcher 42 performs a correlation operation between the common pilot signal and the spread code for a period corresponding to a predetermined path search window width, and generates a delay profile (hereinafter referred to as an instantaneous delay profile). That is, the searcher 42 calculates the correlation power value between the spreading code and the common pilot signal while shifting the phase of the spreading code within the period corresponding to the path search window width. Then, the searcher 42 generates the instantaneous delay profile as information including each calculated correlation power value. Therefore, the instantaneous delay profile includes correlation power values corresponding to each of a plurality of phase spread codes. The common pilot signal is included in the output signal of the RF unit 2, that is, the direct spread spectrum baseband signal for path search. The first updating unit 43 generates a new first average based on the coefficient α output from the coefficient setting unit 41, the instantaneous delay profile output from the searcher 42, and the first average delay profile stored in the first table 44. Generate a delay profile. The first updating unit 43 updates the first average delay profile already stored in the first table 44 to the new first average delay profile. The first table 44 stores a first average delay profile.
[0023]
Based on the instantaneous correlation power value output from the transmission path estimation unit 31b, the coefficient β output from the coefficient setting unit 41, and the average correlation power value stored in the second table 46, the second update unit 45 An average correlation power value is generated. The second update unit 45 updates the average correlation power value already stored in the second table 46 to the new average correlation power value. The second table 46 stores an average correlation power value.
[0024]
Based on the coefficient γ output from the coefficient setting unit 41, the first average delay profile stored in the first table 44, and the average correlation power value stored in the second table 46, the third update unit 47 2 Generate an average delay profile. The third updating unit 47 updates the second average delay profile already stored in the third table 48 to the newly generated second average delay profile. The third table 48 stores the second average delay profile. The path allocation unit 49 determines a path to be allocated to each RAKE finger 31 based on the second average delay profile stored in the third table 48.
[0025]
Next, the operation of the communication terminal apparatus according to the first embodiment configured as described above will be described.
The fluctuation speed estimation unit 40 directly estimates the transmission path of the spread spectrum signal based on the output signal of the RF unit 2. Then, the fluctuation speed estimation unit 40 estimates the fluctuation speed of the transmission path from the estimated state of fluctuation of the transmission path. Various known methods can be used as a method of estimating the fluctuation speed. For example, a method using inner product values of adjacent times disclosed in Japanese Patent Laid-Open No. 2002-94412, a method of measuring fading pitch disclosed in Japanese Patent Laid-Open No. 2002-198865, or a method of measuring signal level fluctuations. Can be used.
[0026]
Now, for example, the path search cycle is 50 ms. In this case, the coefficient setting unit 41 repeatedly executes the process shown in FIG. 2 at a cycle of 50 ms or a multiple of the cycle.
In step ST1, the coefficient setting unit 41 acquires the fluctuation speed output by the fluctuation speed estimation unit 40. In step ST2, the coefficient setting unit 41 determines the category C to which the value of the obtained fluctuation speed belongs. _m Determine. The division is defined by dividing the range of values that can be taken as the fluctuation speed into a plurality (n) of ranges. ₁ , Category C ₂ ..., Category C _n It shall be called.
[0027]
In step ST3, the coefficient setting unit 41 converts the coefficient α to the value α. _m Set to. The value set as the coefficient α is α ₁ , Α ₂ ..., α _n N are prepared in advance. These values are α ₁ Is the smallest, α ₂ , Α _Three ..., α _n It becomes large in order. Thus, the coefficient setting unit 41 has, for example, a variable speed of the section C ₁ The coefficient α is the value α ₁ And the fluctuation speed is Category C _n The coefficient α is the value α _n Set to. In this way, the coefficient setting unit 41 sets the coefficient α to a smaller value as the fluctuation speed is slower. In order to secure a stable reception state, the coefficient α is preferably set to 0 <α <0.5.
[0028]
In step ST4, the coefficient setting unit 41 converts the coefficient β to the value β _m Set to. The value set as the coefficient β is β ₁ , Β ₂ ..., β _n N are prepared in advance. These values are β ₁ Is the smallest, β ₂ , Β _Three ..., β _n It becomes large in order. Thus, the coefficient setting unit 41 indicates that the fluctuation speed is the category C. ₁ The coefficient β is the value β ₁ And the fluctuation speed is Category C _n The coefficient β is the value β _n Set to. Thus, the coefficient setting unit 41 sets the coefficient β to a smaller value as the fluctuation speed is slower. In order to secure a stable reception state, it is desirable to set the coefficient β to 0.5 <β ≦ 1.
[0029]
In step ST5, the coefficient setting unit 41 converts the coefficient γ to the value γ. _m Set to. The value set as the coefficient γ is γ ₁ , Γ ₂ ..., γ _n N are prepared in advance. These values are γ ₁ Is the largest and γ ₂ , Γ _Three ..., γ _n It becomes small in order. Thus, the coefficient setting unit 41 indicates that the fluctuation speed is the category C. ₁ The coefficient γ is ₁ And the fluctuation speed is Category C _n The coefficient γ is _n Set to. Thus, the coefficient setting unit 41 sets the coefficient γ to a larger value as the fluctuation speed is slower. Note that the coefficient γ is desirably set to 1 <γ <10 in order to perform an appropriate reception operation in accordance with the actual reception state.
[0030]
The searcher 42 generates an instantaneous delay profile with a period of 50 ms. And the 1st update part 43 repeatedly performs the process shown in FIG. 3 with a 50 ms period. In step ST11, the first updating unit 43 multiplies each correlation power value included in the average delay profile stored in the first table 44 by a coefficient obtained as (1-α).
[0031]
In step ST12, the first updating unit 43 acquires the instantaneous delay profile newly generated by the searcher 42. In step ST13, the first update unit 43 multiplies each correlation power value included in the acquired instantaneous delay profile by a coefficient α.
[0032]
In step ST <b> 13, the first updating unit 43 calculates the correlations included in the instantaneous delay profile obtained by multiplying the correlation power values included in the first average delay profile stored in the first table 44 by the coefficient α. Add the power values. However, the addition here is addition of correlation power values corresponding to the spread codes of the same phase. Here, for each path, it is possible to compare the correlation power value with a certain threshold value and select only a path having a large level. In step ST <b> 14, the first update unit 43 updates the data in the first table 44 by writing the delay profile including the result of the above addition as a new first average delay profile.
[0033]
In parallel with the execution of the first update process as described above, the second update unit 45 repeatedly executes the process shown in FIG. 4 at a cycle of 10 ms, for example.
In step ST <b> 21, the second update unit 45 multiplies the average correlation power value stored in the second table 46 by a coefficient obtained as (1−β).
[0034]
In step ST22, the second update unit 45 acquires the instantaneous correlation power value newly output by each transmission path estimation unit 31b. In step ST23, the second updating unit 45 multiplies the acquired instantaneous correlation power value by a coefficient β.
[0035]
In step ST24, the second updating unit 45 adds the instantaneous correlation power value obtained by multiplying the average correlation power value stored in the second table 46 by the coefficient β described above. However, the addition here is addition of correlation power values corresponding to the spread codes of the same phase. In step ST <b> 25, the second update unit 45 updates the data in the second table 46 by writing the result of the above addition as a new average correlation power value corresponding to the spreading code of the corresponding phase.
[0036]
In parallel with the execution of the first update process and the second update process as described above, the third update unit 47 repeatedly executes the process shown in FIG. 5 at a cycle of, for example, 50 ms.
In step ST31, the third updating unit 47 multiplies the average correlation power value stored in the second table 46 by a coefficient γ. In step ST32, the third updating unit 47 adds the first average delay profile stored in the first table 44 to the average correlation power value multiplied by the coefficient γ. However, the addition here is addition of correlation power values corresponding to the spread codes of the same phase. In step ST <b> 33, the third updating unit 47 updates the data in the third table 48 by writing the delay profile including the result of the above addition as the second average delay profile.
[0037]
The path allocation unit 49 refers to the second average delay profile stored in the third table 48, selects a path that satisfies the threshold and is equal to or less than the number Rf of the RAKE fingers 31, and allocates the path to each RAKE finger 31. . Specifically, for example, the path allocation unit 49 extracts a correlation power value that is equal to or greater than a threshold value from each correlation power value included in the second average delay profile. Next, the path allocation unit 49 selects, from the extracted correlation power values, up to Rf in descending order of this value. The phase of the spreading code corresponding to the selected correlation power value is the phase of the path to be RAKE combined. Therefore, the path allocation unit 49 allocates a path to each RAKE finger 31 by notifying the RAKE fingers 31 of the phase of the spreading code corresponding to the selected correlation power value.
[0038]
As described above, according to the present embodiment, the instantaneous correlation generated by the RAKE finger 31 so far is added to the first average delay profile generated by averaging the instantaneous delay profiles generated by the searcher 42 so far. By combining the average correlation power values calculated by averaging the power values with those corresponding to the spreading codes of the same phase, a second average delay profile to be referred for path allocation is generated. At this time, the weight of the instantaneous correlation power value when calculating a new average correlation power value is defined by the coefficient β. The coefficient β is adjusted so as to increase as the fluctuation speed of the direct spread spectrum signal transmission path increases. Therefore, an average correlation power value is calculated in consideration of environmental changes. As a result, one of the path search parameters is adaptively changed according to a change in environment, and reception quality can be improved.
[0039]
On the other hand, the combination ratio of the first average delay profile and the average correlation power value when generating a new second average delay profile is defined by a coefficient γ. The coefficient γ is adjusted so as to decrease as the fluctuation speed of the direct spread spectrum signal transmission path increases. Therefore, a second average delay profile is generated taking into account environmental changes. As a result, one of the path search parameters is adaptively changed according to a change in environment, and reception quality can be improved.
[0040]
(Second Embodiment)
FIG. 6 is a block diagram showing a configuration of a communication terminal apparatus for direct spread spectrum communication according to the second embodiment. In FIG. 6, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0041]
As shown in FIG. 6, the communication terminal apparatus according to the second embodiment includes an antenna 1, an RF unit 2, a RAKE receiving unit 3, a multipath search unit 5, an error correction unit 6, and an error detection unit 7. That is, the communication terminal apparatus of the second embodiment includes a multipath search unit 5 instead of the multipath search unit 4 in the first embodiment, and further includes an error correction unit 6 and an error detection unit 7. Note that the error correction unit 6 and the error detection unit 7 may also be included in the first embodiment.
[0042]
The multipath search unit 5 further includes a searcher 42, a first update unit 43, a first table 44, a second update unit 45, a second table 46, a third update unit 47, a third table 48, a path allocation unit 49, and a coefficient. A setting unit 51 is included. That is, the multipath search unit 5 includes a coefficient setting unit 51 instead of the coefficient setting unit 41 in the multipath search unit 4 and does not include the fluctuation speed estimation unit 40.
[0043]
The coefficient setting unit 51 sets the values of the coefficients α, β, and γ based on the error rate output from the error detection unit 7, respectively. The coefficient setting unit 51 outputs the coefficient α to the first update unit 43, the coefficient β to the second update unit 45, and the coefficient γ to the third update unit 47.
[0044]
The error correction unit 6 performs a deinterleaving process and a channel decoding process according to an error correction coding (channel coding) process and an interleaver process performed on the transmission side.
[0045]
The error detection unit 7 detects an error rate of a bit or a bit string by an error detection function such as CRC check or parity check. The error detection unit 7 outputs the detected error rate so that it can be used by the coefficient setting unit 51 and the like.
[0046]
Next, the operation of the communication terminal apparatus of the second embodiment configured as described above will be described.
Now, for example, the path search cycle is 50 ms. In this case, the coefficient setting unit 51 repeatedly executes the process shown in FIG. 7 at a cycle of 50 ms or a multiple of the cycle.
In step ST41, the coefficient setting unit 51 acquires the error rate output by the error detection unit 7. In step ST42, the coefficient setting unit 51 determines the category C to which the acquired error rate value belongs. _p Determine. The division is defined by dividing the range of possible values for the error rate into a plurality (p) of ranges. ₁ , Category C ₂ ..., Category C _p It shall be called.
[0047]
In step ST43, the coefficient setting unit 51 converts the coefficient α to the value α. _p Set to. The value set as the coefficient α is α ₁ , Α ₂ ..., α _q Q in advance are prepared. These values are α ₁ Is the smallest, α ₂ , Α _Three ..., α _q It becomes large in order. Thus, the coefficient setting unit 51 has, for example, an error rate of the category C ₁ The coefficient α is the value α ₁ And the error rate is Category C _q The coefficient α is the value α _q Set to. In this way, the coefficient setting unit 51 sets the coefficient α to a smaller value as the error rate is smaller. In order to secure a stable reception state, the coefficient α is preferably set to 0 <α <0.5.
[0048]
In step ST44, the coefficient setting unit 51 converts the coefficient β to the value β _p Set to. The value set as the coefficient β is β ₁ , Β ₂ ..., β _q Q in advance are prepared. These values are β ₁ Is the smallest, β ₂ , Β _Three ..., β _q It becomes large in order. Thus, the coefficient setting unit 51 has an error rate of category C. ₁ The coefficient β is the value β ₁ And the error rate is Category C _q The coefficient β is the value β _q Set to. As described above, the coefficient setting unit 51 sets the coefficient β to a smaller value as the error rate is smaller. In order to secure a stable reception state, it is desirable to set the coefficient β to 0.5 <β ≦ 1.
[0049]
In step ST45, the coefficient setting unit 51 converts the coefficient γ to the value γ. _p Set to. The value set as the coefficient γ is γ ₁ , Γ ₂ ..., γ _q Q in advance are prepared. These values are γ ₁ Is the largest and γ ₂ , Γ _Three ..., γ _q It becomes small in order. Thus, the coefficient setting unit 51 has an error rate of category C. ₁ The coefficient γ is ₁ And the error rate is Category C _q The coefficient γ is _q Set to. As described above, the coefficient setting unit 51 sets the coefficient γ to a larger value as the error rate is smaller. Note that the coefficient γ is desirably set to 1 <γ <10 in order to perform an appropriate reception operation in accordance with the actual reception state. The path assignment process using the coefficients α, β, and γ set in this way is performed in the same manner as in the first embodiment.
[0050]
As described above, according to the present embodiment, the coefficient α is adjusted so as to increase as the error rate increases. Accordingly, the first average delay profile is generated in consideration of the change in reception quality. As a result, one of the path search parameters is adaptively changed according to the change in reception quality, and the reception quality can be improved.
[0051]
The coefficient β is adjusted so as to increase as the error rate increases. Therefore, an average correlation power value is calculated in consideration of a change in reception quality. As a result, one of the path search parameters is adaptively changed according to the change in reception quality, and the reception quality can be improved.
[0052]
The coefficient γ is adjusted so as to decrease as the error rate increases. Therefore, the second average delay profile is generated in consideration of the change in reception quality. As a result, one of the path search parameters is adaptively changed according to a change in environment, and reception quality can be improved.
[0053]
The first and second embodiments described above can be variously modified as follows.
In the first embodiment, the fluctuation speed estimation unit 40 also performs transmission path estimation. However, since the transmission path estimation is performed in each finger 31 by the transmission path estimation section 31b, the fluctuation speed of the transmission path is estimated using the estimation result in the transmission path estimation section 31b. You can also. A modified configuration example in this case is shown in FIG. The multipath search unit 4 ′ in FIG. 8 includes a fluctuation speed estimation unit 40 ′ instead of the fluctuation speed estimation unit 40 of the multipath search unit 4 in the first embodiment. The fluctuation speed estimation unit 40 ′ does not have a function of directly estimating the transmission path of the spread spectrum signal. Then, the fluctuation speed estimation unit 40 ′ estimates the fluctuation speed of the transmission path based on the output of the transmission path estimation unit 31 b of each finger 31.
[0054]
In the first and second embodiments, the coefficients α, β, and γ may be calculated each time by substituting the transmission path fluctuation speed and error rate into a previously prepared calculation formula.
[0055]
In the first embodiment, the coefficient α may be a fixed value. Either the coefficient β or the coefficient γ may be a fixed value.
[0056]
In the second embodiment, any two of the coefficients α, β, and γ may be fixed values.
[0057]
In the first and second embodiments, the processing method for weighted averaging in the first updating unit 43 and the second updating unit 45 and the processing method for synthesis in the third updating unit 47 are appropriately determined. It can be changed.
[0058]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
[0059]
【The invention's effect】
According to the present invention, various coefficients, which are one of the path search parameters, are adaptively adjusted according to the fluctuation speed and error rate of the multipath, so that stable reception operation can be performed in response to changes in the environment. A useful path can be determined so that it can be secured.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a communication terminal apparatus for direct spread spectrum communication according to a first embodiment.
FIG. 2 is a flowchart of processing performed by a coefficient setting unit 41 in FIG.
3 is a flowchart of processing performed by a first updating unit 43 in FIG.
FIG. 4 is a flowchart of processing performed by a second updating unit 45 in FIG.
FIG. 5 is a flowchart of processing performed by a third update unit 47 in FIG.
FIG. 6 is a block diagram showing a configuration of a communication terminal apparatus for direct spread spectrum communication according to the second embodiment.
7 is a flowchart of processing performed by a coefficient setting unit 51 in FIG.
FIG. 8 is a block diagram showing a modified configuration of the communication terminal apparatus for direct spread spectrum communication according to the first embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... RF part, 3 ... RAKE receiving part, 4, 5 ... Multipath search part, 6 ... Error correction part, 7 ... Error detection part, 31 ... Finger, 31a ... Despreading part, 31b ... Transmission path Estimating unit, 32 ... combining unit, 40 ... fluctuating speed estimating unit, 41, 51 ... coefficient setting unit, 42 ... searcher, 43 ... first updating unit, 44 ... first table, 45 ... second updating unit, 46 ... first 2 tables, 47... Third update unit, 48... Third table, 49.

Claims (12)

A first instantaneous correlation power value between a multiwave signal including a plurality of direct spread spectrum signals received via a multipath and a spread code having a phase corresponding to a path useful for RAKE combining among the multipaths. A plurality of calculation means each for calculating periodically;
Means for obtaining a first average correlation power value by periodically weighted averaging the first instantaneous correlation power value according to a first coefficient;
Means for periodically calculating a second instantaneous correlation power value between the multi-wave signal and each of spreading codes having a number of phases larger than the number of the calculating means;
Means for obtaining a second average correlation power value by periodically weighted averaging the second instantaneous correlation power values according to a second coefficient, respectively;
Third average correlation power values by periodically synthesized weight corresponding to said first average correlation power values corresponding to the spreading code of the same phase as the second average correlation power values with each other to the third coefficient A means of seeking
Means for determining the useful path based on the third average correlation power value;
A path search device comprising: changing means for changing at least one of the first coefficient, the second coefficient, and the third coefficient in accordance with a fluctuation speed of the multipath. The first coefficient is proportional to the weight in the weighted averaging of the newly calculated first instantaneous correlation power value,
2. The path search device according to claim 1, wherein the changing unit increases the first coefficient as the fluctuation speed of the multipath increases. The second coefficient is proportional to the weight in the weighted averaging of the newly calculated second instantaneous correlation power value,
2. The path search device according to claim 1, wherein the changing unit increases the second coefficient as the fluctuation speed of the multipath increases. The third coefficient is proportional to the weight in the synthesis of the first average correlation power value,
2. The path search device according to claim 1, wherein the changing unit reduces the third coefficient as the multipath fluctuation speed increases . A first instantaneous correlation power value between a multiwave signal including a plurality of direct spread spectrum signals received via a multipath and a spread code having a phase corresponding to a path useful for RAKE combining among the multipaths. A plurality of calculation means each for calculating periodically;
Means for obtaining a first average correlation power value by periodically weighted averaging the first instantaneous correlation power value according to a first coefficient;
Means for periodically calculating a second instantaneous correlation power value between the multi-wave signal and each of spreading codes having a number of phases larger than the number of the calculating means;
Means for obtaining a second average correlation power value by periodically weighted averaging the second instantaneous correlation power values according to a second coefficient, respectively;
Third average correlation power is obtained by periodically synthesizing the first average correlation power value and the second average correlation power value with weights corresponding to third coefficients corresponding to spreading codes having the same phase. A means for determining the value;
Means for determining the useful path based on the third average correlation power value;
And changing means for changing at least one of the first coefficient, the second coefficient, and the third coefficient in accordance with an error rate of data obtained by RAKE combining the useful multipath. Characteristic path search device. The first coefficient is proportional to the weight in the weighted averaging of the newly calculated first instantaneous correlation power value,
6. The path search device according to claim 5, wherein the changing unit increases the first coefficient as the error rate increases. The second coefficient is proportional to the weight in the weighted averaging of the newly calculated second instantaneous correlation power value,
6. The path search device according to claim 5, wherein the changing unit increases the second coefficient as the error rate increases. The third coefficient is proportional to the weight in the synthesis of the first average correlation power value,
6. The path search device according to claim 5, wherein the changing unit reduces the third coefficient as the error rate increases. Means for receiving a multi-wave signal including a plurality of direct spread spectrum signals transmitted over multipath;
A plurality of calculating means for periodically calculating a first instantaneous correlation power value between the multiwave signal and a spread code of a phase corresponding to a path useful for RAKE combining among the multipaths;
Means for obtaining a first average correlation power value by periodically weighted averaging the first instantaneous correlation power value according to a first coefficient;
Means for periodically calculating a second instantaneous correlation power value between the multi-wave signal and each of spreading codes having a number of phases larger than the number of the calculating means;
Means for obtaining a second average correlation power value by periodically weighted averaging the second instantaneous correlation power values according to a second coefficient, respectively;
Third average correlation power values by periodically synthesized weight corresponding to said first average correlation power values corresponding to the spreading code of the same phase as the second average correlation power values with each other to the third coefficient A means of seeking
Means for determining the useful path based on the third average correlation power value;
A plurality of despreading means for despreading the multi-wave signal with a spreading code having a phase corresponding to the useful path;
Means for RAKE combining the respective outputs of the despreading means;
A communication terminal apparatus comprising: changing means for changing at least one of the first coefficient, the second coefficient, and the third coefficient in accordance with a fluctuation speed of the multipath. Means for receiving a multi-wave signal including a plurality of direct spread spectrum signals transmitted over multipath;
A plurality of calculating means for periodically calculating a first instantaneous correlation power value between the multiwave signal and a spread code of a phase corresponding to a path useful for RAKE combining among the multipaths;
Means for obtaining a first average correlation power value by periodically weighted averaging the first instantaneous correlation power value according to a first coefficient;
Means for periodically calculating a second instantaneous correlation power value between the multi-wave signal and each of spreading codes having a number of phases larger than the number of the calculating means;
Means for obtaining a second average correlation power value by periodically weighted averaging the second instantaneous correlation power values according to a second coefficient, respectively;
Third average correlation power values by periodically synthesized weight corresponding to said first average correlation power values corresponding to the spreading code of the same phase as the second average correlation power values with each other to the third coefficient A means of seeking
Means for determining the useful path based on the third average correlation power value;
A plurality of despreading means for despreading the multi-wave signal with a spreading code having a phase corresponding to the useful path;
Means for RAKE combining the respective outputs of the despreading means;
A communication terminal apparatus comprising: changing means for changing at least one of the first coefficient, the second coefficient, and the third coefficient in accordance with an error rate of data obtained by the RAKE combining. A first instantaneous correlation power value between a multiwave signal including a plurality of direct spread spectrum signals received via a multipath and a spread code having a phase corresponding to a path useful for RAKE combining among the multipaths. Each of them is periodically calculated by a plurality of calculation means,
A first average correlation power value is obtained by periodically weighted averaging the first instantaneous correlation power values according to a first coefficient,
Periodically calculating a second instantaneous correlation power value between the multi-wave signal and each of spread codes having a number of phases larger than the number of the calculation means;
A second average correlation power value is obtained by periodically weighted averaging the second instantaneous correlation power values according to a second coefficient,
Third average correlation power values by periodically synthesized weight corresponding to said first average correlation power values corresponding to the spreading code of the same phase as the second average correlation power values with each other to the third coefficient Seeking
Determining the useful path based on the third average correlation power value;
A path search method, wherein at least one of the first coefficient, the second coefficient, and the third coefficient is changed in accordance with a fluctuation speed of the multipath. A first instantaneous correlation power value between a multiwave signal including a plurality of direct spread spectrum signals received via a multipath and a spread code having a phase corresponding to a path useful for RAKE combining among the multipaths. Each of them is periodically calculated by a plurality of calculation means,
A first average correlation power value is obtained by periodically weighted averaging the first instantaneous correlation power values according to a first coefficient,
Periodically calculating a second instantaneous correlation power value between the multi-wave signal and each of spread codes having a number of phases larger than the number of the calculation means;
A second average correlation power value is obtained by periodically weighted averaging the second instantaneous correlation power values according to a second coefficient,
Third average correlation power values by periodically synthesized weight corresponding to said first average correlation power values corresponding to the spreading code of the same phase as the second average correlation power values with each other to the third coefficient Seeking
Determining the useful path based on the third average correlation power value;
A path search method that changes at least one of the first coefficient, the second coefficient, and the third coefficient in accordance with an error rate of data obtained by RAKE combining the useful multipath. .

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