JP3292186B2 - CDMA receiver, multipath finger assignment method thereof, and recording medium recording control program therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA receiving apparatus, a multipath finger assigning method thereof, and a recording medium on which a control program is recorded. The present invention relates to a multipath finger assignment method used for detecting a path to be selected.

[0002]

2. Description of the Related Art DS-CDMA (Direct Seq)
uence-Code Division Mul
A single access (direct access-code division multiple access system) is a system in which a plurality of communicating parties communicate using the same frequency band, and each communicating party is identified using a spreading code.

In mobile communication, since the propagation path length of each received wave in multiplex wave propagation varies, multiplex waves having different propagation delay times interfere with each other. In DS-CDMA communication, since information data is band-spread with a high-rate spreading code having a shorter cycle than the propagation time, each multiplex wave having a different propagation delay time can be separated and extracted.

Since the mobile station fluctuates with respect to the base station, this delay profile (signal power distribution with respect to delay time)
Also fluctuates over time. In addition, the signal of each path fluctuates by Rayleigh in places other than the line of sight.

[0005] In DS-CDMA communication, a plurality of Rayleigh-varying multipath signals having different propagation delay times separated by time are gathered and in-phase combined (Rake combined) to obtain a diversity effect and improve reception characteristics. . Alternatively, for a certain reception quality (bit error rate), the transmission power can be reduced by the diversity effect associated with Rake combining, so that the interference power to other users within the same cell and outside the cell is reduced. Therefore, the subscriber capacity in a certain frequency band can be increased.

However, as described above, since the mobile station changes relative to the base station, the delay profile also changes, and the delay time of the path to be rake-combined also changes. Therefore, in a mobile communication environment, a receiver is required to have a multipath search and tracking function that follows a change in a delay profile and can perform Rake combining on a plurality of paths where the maximum signal power is obtained instantaneously. .

For example, as shown in FIG. 13, the CDMA receiving apparatus includes a multipath search unit (multipath detecting means) 24 according to a communication environment and a Rake combining reception for combining a plurality of paths in phase (RAKE combining). And a unit 25. 21 is an antenna, 22
Denotes a high-frequency receiving circuit, and 23 denotes an A / D (analog / digital) converter.

In the conventional CDMA receiving system having such a configuration, the delay profile (signal power distribution with respect to delay time) is measured by the multipath search unit 24, and some paths having large signal power are selected within the measurement range. , Rake combining receiving section 25 is notified of the timing of the path. The Rake combining / receiving unit 25 performs despreading for each path based on the timing information and performs Rake combining to obtain a path diversity effect.

In some cases, the rake combining and receiving section 25 has means (path tracking) for following the movement of a path specified separately. In such a case, the multipath search section 24 has at least an initial or fixed path. It is necessary to notify the Rake combining / receiving unit 25 of the path information for each cycle. The CDMA receiver and the multipath search method are disclosed in Japanese Patent Application Laid-Open No. 9-181704.

On the other hand, as a conventional method of assigning multipaths to fingers, there is a method as shown in FIG.
In this method, first, a delay profile of a propagation path is measured by a matched filter, a sliding correlator, or the like (step S81 in FIG. 14).

Subsequently, upper correlation peaks are detected from the measured delay profile by the number of fingers of the Rake receiver (steps S82 and S83 in FIG. 14), and the detected path timing is used as the despread timing of each finger. Assigned (step S84 in FIG. 14).

[0012]

In the above-described conventional multipath finger assignment method, the pilot symbols periodically included in the received signal are used, and the phase of each information symbol is set as the pilot symbol phase as a reference phase. When performing pilot interpolation supplemental synchronous detection to estimate, when the assignment path to the finger is switched,
Since the pilot phase jumps, symbol synchronization by pilot interpolation complementation cannot be temporarily achieved. For this reason, if the switching of each finger path is not made as small as possible, the reception characteristics deteriorate.

In the case of the above method, for example, in a rake receiver having three fingers, when the power of the third correlation peak and the fourth correlation peak of the delay profile are substantially equal, the propagation path , The third and fourth path timings are frequently switched. As a result, the path timing (despreading timing) assigned to one of the fingers is frequently switched, and the reception characteristics are significantly deteriorated.

Further, as another example, for the sake of simplicity, considering a one-finger receiver, if delay profiles of the same level of two paths are measured, the allocation to the fingers will be a subtle fluctuation of the reception level. As a result, the path A is assigned or the path B is assigned, so that the path is frequently switched, and the reception characteristics are degraded.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to prevent frequent switching of path assignments to fingers, to prevent flapping of path assignments, and to improve reception characteristics. It is an object of the present invention to provide a CDMA receiving apparatus, a multipath finger assigning method thereof, and a recording medium recording a control program therefor.

[0016]

A CDMA receiving apparatus according to the present invention is a CDMA receiving apparatus including a plurality of finger units for despreading one path and synchronizing symbols with each other. A state weighting function calculated from the current assignment state of the above is calculated into a delay profile indicating a signal power distribution with respect to a delay time of a received signal to the path, and the level of the path currently assigned to the plurality of finger units is superior. And then search multiple paths.

Another CDMA receiving apparatus according to the present invention is a CDMA receiving apparatus including a plurality of finger units for performing despreading for one path and performing symbol synchronization, and
Calculating means for calculating a state weighting function for giving priority to the level of a path currently allocated to the plurality of finger parts from the current allocation state to the plurality of finger parts; and Computing means for computing a state weighting function into a delay profile indicating a signal power distribution with respect to the delay time of a received signal to the path, and retrieval means for retrieving a plurality of paths from computation results of the computing means.

Another CDMA receiving apparatus according to the present invention is a CDMA receiving apparatus including a plurality of finger units for performing despreading for one path to obtain symbol synchronization.
Search means for searching a plurality of paths from a delay profile indicating a signal power distribution with respect to a delay time of a received signal to the path, and a path of a new candidate taken out by the search means and a finger currently assigned to the plurality of finger units. The path of the new candidate and the path of the new candidate after calculating a weighting function set in advance to the delay profile corresponding to one of the Determining means for determining which of the paths currently allocated to the plurality of finger portions is to be allocated;

A multipath finger assignment method for a CDMA receiving apparatus according to the present invention is a multipath finger assigning method for a CDMA receiving apparatus including a plurality of finger sections for despreading one path and synchronizing symbols. Calculating a state weighting function calculated from a current assignment state to the plurality of finger parts into a delay profile indicating a signal power distribution with respect to a delay time of a reception signal to the path, and currently assigning the plurality of finger parts to the plurality of finger parts. The level of a given path is set to be superior, and then a plurality of paths are searched.

Another multi-path finger assigning method for a CDMA receiving apparatus according to the present invention is a multi-path finger assigning method for a CDMA receiving apparatus including a plurality of finger units for despreading one path and synchronizing symbols. Calculating a state weighting function for giving priority to a level of a path currently assigned to the plurality of finger sections from a current assignment state to the plurality of finger sections; and the calculated state The method includes a step of calculating a weighting function into a delay profile indicating a signal power distribution with respect to a delay time of a reception signal to the path, and a step of searching a plurality of paths from the calculation result.

According to another aspect of the present invention, there is provided a multi-path finger allocating method for a CDMA receiving apparatus including a plurality of finger units for despreading one path and performing symbol synchronization. Retrieving a plurality of paths from a delay profile indicating a signal power distribution with respect to a delay time of a received signal to the path, and currently assigning a new candidate path extracted in the search and the plurality of finger units And calculating a weighting function set in advance for the delay profile corresponding to one of the plurality of finger sections to make the level of the path currently assigned to the plurality of finger sections superior, and then setting the path of the new candidate And a path currently assigned to the plurality of finger units. And a flop.

[0022]

[0023]

A recording medium in which a multipath finger assignment control program of another CDMA receiving apparatus according to the present invention is recorded is a CDMA receiving apparatus including a plurality of finger units for despreading one path and synchronizing symbols. A recording medium recording a finger assignment control program for causing a computer to perform multipath finger assignment, wherein the finger assignment control program indicates to the computer a signal power distribution with respect to a delay time of a reception signal to the path. A plurality of paths are searched from the delay profile, and a weight set in advance to the delay profile corresponding to one of a path of a new candidate extracted in the search and a path currently allocated to the plurality of finger units Calculate a function and add it to the multiple fingers Is made to determine whether assign one of the paths that are currently assigned to the path and the plurality of fingers of the new candidate levels of paths that are resident allocated from the dominant.

That is, the CDMA receiving apparatus of the present invention
The multipath detection unit (path search unit) of the CDMA (Spread Spectrum Communication) Rake receiving apparatus performs state weighting on the measured delay profile, which is calculated from the current allocation state to the Rake fingers. In addition, it is possible to provide a hysteresis to the path replacement level of the finger, thereby preventing frequent path switching leading to characteristic deterioration. Thereby, reception characteristics are improved.

More specifically, the CDMA receiving apparatus according to the present invention has a multipath search section in the CDMA system,
It has a receiver (Rake receiver) that can combine and demodulate a plurality of multipaths in phase.

The multipath search section of the CDMA receiver according to the present invention is mounted on a DSP (Digital Signal Processor) and operates under program control. This CDM
The A receiving device includes an antenna, a high-frequency receiving circuit, an A / D converter for converting an analog signal to a digital signal,
A plurality of fingers for despreading and symbol synchronization for one path, a Rake combining receiver for in-phase combining the received signals of the plurality of fingers, a sliding correlator as delay profile measuring means, and hardware or DSP or the like. A delay profile power adding section configured by a processor, a state weighting section determined based on the current finger assignment state, a correlation peak position detecting section for searching a multipath from the delay profile, and assigning the detected multipath to each finger. And a path allocation unit.

As in the above configuration, since the weighting unit for giving priority to the level of the path currently allocated to the finger is provided, it is possible to prevent frequent path switching leading to characteristic deterioration.

Therefore, even in a communication environment in which multipaths are observed at substantially the same level, the effect of having a hysteresis in the path switching level can be obtained, so that the paths are not frequently switched to the fingers. In addition, it is possible to prevent flapping of the path assignment, and to improve the reception characteristics.

Further, even when the path is temporarily lost due to shadowing or the like, there is an effect that the path position of the finger can be protected, and the reception characteristics can be improved. Further, since the condition branch determination at the time of path switching is simplified, the hardware configuration and the software configuration can be simplified.

[0031]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a multipath search unit according to an embodiment of the present invention. In the figure, in the embodiment of the present invention, a multipath search unit is a DSP (digital signal processor) 1.
And operate by program control.

The CDMA receiver includes a DSP 1, an antenna 2, a high-frequency receiving circuit 3, an A / D (analog / digital) converter 4 for converting an analog signal into a digital signal, and a despreading and symbol A plurality of finger units 5 for synchronization, a Rake combining receiver 6 for in-phase combining (Rake combining) the received signals of the plurality of finger units 5, a sliding correlator 7 as delay profile measuring means, hardware or DSP, etc. And a delay profile power adder 8 composed of the above processors.

The DSP 1 comprises a weighting unit 11 comprising an arithmetic unit 12 and a state weighting unit 13 determined from the current finger assignment state; a correlation peak position detecting unit 14 for searching for a multipath from a delay profile; Is assigned to each finger, and a control memory 16 that stores a program executed by each unit in the DSP 1.
Further, the DSP 1 does not necessarily have to be a DSP dedicated to path search, and other functions such as a speech codec may be implemented.

As the arithmetic unit 12, an adder or a multiplier for weighting the position assigned to the finger unit 5, or a subtractor or a divider for weighting a position not assigned to the finger unit 5 And so on.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows a CDMA according to an embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a multipath search unit of the receiving device. In the figure, a multipath search unit according to one embodiment of the present invention is mounted on a DSP 1 and operates under program control.

A CDMA receiving apparatus according to one embodiment of the present invention comprises a DSP 1, an antenna 2, a high-frequency receiving circuit 3,
A / D (analog / digital) conversion unit 4 for converting an analog signal into a digital signal, a plurality of finger units 5 for despreading and symbol synchronization for one path, and in-phase synthesis of reception signals of the plurality of finger units 5 It comprises a Rake combining receiver 6 for performing (Rake combining), a sliding correlator 7 as delay profile measuring means, and a delay profile power adder 8 composed of hardware or a processor such as a DSP.

The DSP 1 comprises a weighting section 11 comprising a multiplier 12 and a state weighting section 13 determined from the current finger assignment state; a correlation peak position detecting section 14 for searching a multipath from a delay profile; Is assigned to each finger, and a control memory 16 that stores a program executed by each unit in the DSP 1.
Further, the DSP 1 does not necessarily have to be a DSP dedicated to path search, and other functions such as a speech codec may be implemented.

[0038] FIG. 3 is a diagram showing a weighting operation by the weighting unit 11 of FIG. FIG. 3A shows the weighting function f
3 (t), and FIG. 3 (b) shows the delay profile D
(T) shows a, FIG. 3 (c) shows the output of the multiplier 12 of FIG.

FIG. 4 is a flowchart showing the processing operation of the multipath search unit (DSP1) according to one embodiment of the present invention. The detailed operation of the multipath search unit according to one embodiment of the present invention will be described with reference to FIGS. Note that the processing operation shown in FIG.
The control memory 16 is realized by executing the program 6 and a ROM (Read Only Memory) or a floppy disk can be used.

At the start of the path assignment operation, the state weighting unit 13 sets the weighting function f (t) = 1 (step S1 in FIG. 4). After that, the signal received by the antenna 2 is down-converted by the high-frequency receiving circuit unit 3 and A / A
The signal is converted into a digital signal by the D converter 4. The sliding correlator 7 obtains a delay profile from the signal converted into a digital signal by the A / D converter 4.

The delay profile power adder 8 averages the path variation of the delay profile obtained by the sliding correlator 7 by fading or the like. The delay profile D (t) after the path fluctuation is averaged by the delay profile power adding unit 8 is calculated by the multiplier 1 of the weighting unit 11.
2, the weighting function f from the state weighting unit 13
(T) (step S2 in FIG. 4).

The correlation peak detector 14 calculates the upper N fingers of the delay profile from the delay profile [f (t) * D (t)] multiplied by the weighting function f (t) by the multiplier 12 of the weighting unit 11. The peak delay time is detected (step S3 in FIG. 4). Here, N fingers are the number of finger units 5 (the number of fingers of the Rake receiver).

The rake path allocator 15 transmits the path timing detected by the correlation peak detector 14 to each finger 5 (step S4 in FIG. 4). State weighting unit 1
Reference numeral 3 sets a weighting function f (t) for weighting the state based on the assigned path position of the finger unit 5 (step S5 in FIG. 4). That is, the state weighting unit 13 sets the weighting function f (t) such that the peak value at the current allocation position becomes large.

For example, as the weighting function f (t),
Assuming that the number of fingers (Nfinger) is n, the despreading timing (multipath delay time) assigned to each finger unit 5 is Ti, and the width near the correlation peak is τ,

(Equation 1) Is given by the formula Here, α> 1 (for example, α =
(About 1.5), or the width τ in the vicinity of the correlation peak may be set to about one chip.

The above process is repeated until the path assignment operation is completed (Step S6 in FIG. 4). As a result, in the delay profile from the next time, as shown in FIG. 3, the path currently assigned to the finger unit 5 is set to a superior level.

In order for the finger unit 5 assigned to the path (3) in FIG. 3 to switch to the path (4), the path (4) needs to be α times larger than the path (3). Therefore, hysteresis can be provided for the path exchange, and frequent path switching between (3) and (4) in FIG. 3 can be prevented. Further, even when the path is temporarily lost due to shadowing, the previous path position can be held.

FIG. 5 is a flowchart showing the setting processing of the weighting function by the state weighting unit 13 of FIG. The setting processing of the weighting function by the state weighting unit 13 will be described with reference to FIGS.

At the start of the path assignment operation, the state weighting unit 13 sets the weighting function f (t) = 1 (step S11 in FIG. 5). Thereafter, when the path position assigned to each finger unit 5 is input from the rake path assignment unit 15 (step S12 in FIG. 5), a weighting function f (t) for state weighting is set based on the path position. (Step S13 in FIG. 5). This setting process of the weighting function is repeatedly performed until the path assignment operation is completed (Step S14 in FIG. 5).

[0049] FIG 6 is a flowchart showing a processing operation of the correlation peak position detection unit 14 of FIG. The processing operation of the correlation peak position detector 14 will be described with reference to FIGS.

The correlation peak position detecting section 14 performs a maximum value search to detect a plurality of peaks (step S2 in FIG. 6).
1) After storing the maximum peak position (step S2 in FIG. 6)
2) Mask the detected peak position data (mask the detected maximum peak data with 0) (FIG. 6, step S23). The correlation peak position detection unit 14 excludes the data of the detected peak position by masking the data of the peak position, and thereafter performs the above-described processing on the data of the remaining peak positions by the preset number of detected peaks. The same processing operation as described above is repeated (step S24 in FIG. 6).

[0051] FIG. 7 is a flowchart showing a maximum value search processing by the correlation peak position detection unit 14 of FIG. The maximum value search processing by the correlation peak position detection unit 14 will be described with reference to FIGS.

The correlation peak position detecting section 14 first reads the initial value of the maximum value (for example, sets the leading value of the data), and sets the search start address (step S3 in FIG. 7).
1). Subsequently, the correlation peak position detection unit 14 reads data from a memory (not shown), and advances the read address to the next data position (Step S32 in FIG. 7).

The correlation peak position detector 14 compares the data read from the memory with the maximum value data (step S in FIG. 7).
33) If the data is larger than the maximum value (step S34 in FIG. 7), the maximum value is replaced and the maximum value position is stored in a storage unit (not shown) (step S35 in FIG. 7). The correlation peak position detector 14 repeats the same processing operation as described above until all the search data have been compared with the maximum value (Step S36 in FIG. 7).

In the above-described embodiment of the present invention, the weight of the position assigned to the
However, it is also possible to use an adder or the like, and to weight a position that is not assigned to the finger unit 5 by using a subtractor or a divider. .

FIG. 8 is a flowchart showing the setting processing of the weighting function by the state weighting unit according to another embodiment of the present invention. The configuration of the multipath search unit according to another embodiment of the present invention is the same as the configuration of the multipath search unit according to one embodiment of the present invention shown in FIG. With reference to FIGS. 2 and 8, a description will be given of the setting processing of the weighting function by the state weighting unit according to another embodiment of the present invention.

At the start of the path assignment operation, the state weighting unit 13 sets the weighting function f (t) = 1 (step S41 in FIG. 8). Thereafter, the state weighting unit 13 determines whether or not the path search unit is tracking the delay profile measurement range so that the path with the maximum received peak power is centered (step S42 in FIG. 8), and determines that the track is being tracked. When it is determined, a coefficient that makes only the past maximum peak position dominant is set as a weighting function f (t) for weighting the state (step S46 in FIG. 8).

On the other hand, when the state weighting unit 13 determines that the track is not tracked, and the path position allocated to each finger unit 5 is input from the rake path allocation unit 15 (FIG. 8).
In step S43, a weighting function f (t) for weighting the state is set based on the path position (step S in FIG. 8).
44). This weighting function setting process is repeatedly performed until the path assignment operation is completed (step S45 in FIG. 8).

As described above, when the path search unit tracks the delay profile measurement range so that the path of the maximum received peak power is centered, a coefficient is applied that makes only the past maximum peak position superior. By matching, it is possible to prevent the measurement position from fluttering. Since the reception timing can be prevented from fluttering, the transmission timing controlled in accordance with the reception timing can be prevented from fluttering.

FIG. 9 shows a CDMA according to another embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a multipath search unit of the receiving device. In the figure, a multipath search unit according to another embodiment of the present invention includes a DSP 1 as in the embodiment of the present invention.
And operate under program control.

A CDMA according to another embodiment of the present invention
The receiving apparatus has the same configuration as that of the embodiment of the present invention except that weighting is performed by the rake path allocating unit 17 of the DSP 1 instead of the weighting unit 11 of FIG.
The same components are denoted by the same reference numerals. The operation of the same component is the same as that of the embodiment of the present invention.

The rake path allocating section 17 is provided with a path replacement determining section 18 for weighting the positions allocated to the finger sections 5, and the path replacement determining section 18 determines the level of the new candidate path by the finger. By comparing the level of the path assigned to the unit 5 with the result of the calculation (multiplication, addition, etc.) of the flutter prevention coefficient (corresponding to the above-mentioned weighting coefficient), it is determined whether or not the path should be replaced.

FIG. 10 is a flowchart showing the path replacement determination processing of the path replacement determination unit 18 of FIG. A detailed operation of the multipath search unit according to another embodiment of the present invention will be described with reference to FIGS.
Note that the processing operation shown in FIG. 10 is realized by the path replacement determination unit 18 executing a program in the control memory 16, and a ROM, a floppy disk, or the like can be used as the control memory 16.

The signal received by the antenna 2 is down-converted by the high-frequency receiving circuit 3 and converted into a digital signal by the A / D converter 4. The sliding correlator 7 obtains a delay profile from the signal converted into a digital signal by the A / D converter 4.

The delay profile power adder 8 averages path fluctuations by fading or the like with respect to the delay profile obtained by the sliding correlator 7. The delay profile after the path fluctuation is averaged by the delay profile power adding unit 8 is input to the correlation peak detecting unit 14.

The correlation peak detector 14 detects the delay time of the upper Nfinger peak of the delay profile from the delay profile. Here, Nfinger is the number of fingers 5 (the number of fingers of the Rake receiver).

In the rake path allocating unit 17, the path replacement determining unit 18 checks the path timing (path position) detected by the correlation peak detecting unit 14 (step S51 in FIG. 10), and determines whether there is a new candidate path. A determination is made (step S52 in FIG. 10). Pass replacement judgment unit 18
If there is no new candidate path, the conventional path assignment remains (step S56 in FIG. 10).

On the other hand, if there is a new candidate path, the path replacement determining unit 18 multiplies the level of the path allocated to the finger unit 5 by the flutter prevention coefficient (for example, if the path is 1.5, the pass level is 1.5). Multiplied by the level of the new candidate) and the level of the new candidate path.

In this case, if the value obtained by multiplying the flutter prevention coefficient is higher than the level of the new candidate path (step S53 in FIG. 10), the path replacement determining unit 18 keeps the conventional path allocation (step S56 in FIG. 10). ).

Conversely, if the value obtained by multiplying the flutter prevention coefficient is lower than the level of the new candidate path (step S53 in FIG. 10), the path assigned to the conventional finger unit 5 is replaced with the new candidate path (FIG. 10). FIG. 10 step S54).

The path exchange processing by the path exchange determining unit 18 is repeatedly performed until the path assignment is completed (step S55 in FIG. 10) (step S51 in FIG. 10).
~ S56).

In the processing of step S53 by the path replacement determining unit 18, the level of the path assigned to the finger unit 5 is multiplied by the flutter prevention coefficient. However, the flutter prevention coefficient may be added. Further, the level of the new candidate path may be multiplied, subtracted, or divided by the flutter prevention coefficient so that the path currently assigned to the finger unit 5 has the superior level.

The rake path allocating unit 17 transmits the path allocated in the path switching process by the path switching determining unit 18 to each finger unit 5. As a result, in the delay profile from the next time, the path currently assigned to the finger unit 5 is set to a superior level.

As a result, hysteresis can be provided for the path exchange, and frequent path switching between neighboring paths of the same level can be prevented. Also,
Even when a path is temporarily lost due to shadowing, the previous path position can be held.

FIG. 11 is a flowchart showing the protection operation of the previous pass position according to another embodiment of the present invention. With reference to FIG. 11, the operation of protecting the previous path position according to another embodiment of the present invention will be described.

When protecting the previous path position, the path replacement determining unit 18 detects the path of the assigned finger phase (step S61 in FIG. 11) and assigns the same position as the previous path position (step S61 in FIG. 11). S62),
A counter (not shown) for counting the number of times the previous pass position could not be detected is reset (step S6 in FIG. 11).
3).

On the other hand, unless the path replacement determination unit 18 detects a path of the phase of the assigned finger (FIG. 11).
In step S61, the number of times the previous pass position could not be detected is compared with a preset set value (step S65 in FIG. 11). If the number of times the previous path position could not be detected is larger than the set value, the path replacement determining unit 18 assigns another path instead of the previous path position (step S66 in FIG. 11).

If the number of times the previous pass position could not be detected is smaller than the set value, the path replacement determining unit 18 assigns the same position as the previous pass position (step S67 in FIG. 11). One is added to the number of times the path position could not be detected (step S68 in FIG. 11). The path exchange determination unit 18 repeats the above processing (steps S61 to S68 in FIG. 11) until the previous path position protection processing ends (step S64 in FIG. 11).

FIG. 12 is a flowchart showing the operation of protecting a newly allocated path position according to another embodiment of the present invention. With reference to FIG. 12, a description will be given of the operation of protecting a newly allocated path position according to another embodiment of the present invention.

When protecting a newly assigned path position,
When detecting the path of the newly assigned phase (step S71 in FIG. 12), the path replacement determining unit 18 assigns the same position as the newly assigned path position (step S7 in FIG. 12).
2), a counter (not shown) for counting the number of times the newly assigned path position could not be detected is reset (FIG. 1).
2 step S73).

On the other hand, if the path replacement determination unit 18 does not detect a path with a newly assigned phase (step S12 in FIG. 12).
71), the number of times the newly allocated path position could not be detected is compared with a preset setting value (step S75 in FIG. 12). If the number of times the above-mentioned newly allocated path position cannot be detected is larger than the set value, the path replacement determining unit 18 allocates another path instead of the newly allocated path position (step S76 in FIG. 12).

If the number of times that the above-mentioned newly allocated path position cannot be detected is smaller than the set value, the path replacement determining unit 18 allocates the same position as the newly allocated path position (step S77 in FIG. 12). One is added to the number of times the newly assigned path position could not be detected (step S78 in FIG. 12). The path replacement determination unit 18 continues until the protection processing of the newly allocated path position ends (FIG. 12).
Step S74), the above processing is repeated (FIG. 12, steps S71 to S78).

As described above, even in a communication environment where multipaths are observed at substantially the same level, frequent allocation of paths to the finger units 5 does not occur. Therefore, it is possible to prevent flapping of the path assignment and improve the reception characteristics.

Further, even when the path is temporarily lost due to shadowing or the like, the path position of the finger unit 5 can be protected, and the reception characteristics can be improved. Furthermore, since the condition branch determination at the time of path switching is simplified, the hardware configuration and the software configuration can be simplified.

In the above-described embodiments and their explanations, the processing for signals received from one base station has been described in order to simplify the explanation of the operation. , The above processing may be performed on each of the received signals from each base station due to soft handover or the like.
In that case, the above-described circuits may be provided for each base station or may be shared by each base station.

Further, among the peak positions detected by the above method, in a Rake receiving apparatus having three fingers, for example, a peak position which satisfies a predetermined condition, a third correlation peak of the delay profile and a third correlation peak are used. When the power of the fourth correlation peak is almost equal to that of the fourth correlation peak, a weighting function can be calculated for the third correlation peak. In this case, the third path timing and the fourth path timing are not frequently exchanged due to the fluctuation of the propagation path, so that one of the fingers frequently has an assigned path timing (despreading timing). Switching does not occur, and the reception characteristics can be improved.

[0086]

As described above, according to the present invention, 1
In a CDMA receiver including a plurality of fingers for despreading and symbol synchronization for one path, a state weighting function calculated from a current assignment state to the plurality of fingers is calculated based on a signal power with respect to a delay time of a received signal to the path. By multiplying by a delay profile indicating a distribution and then searching for a multipath, it is possible to prevent frequent switching of the path allocation to the finger unit, prevent flapping of the path allocation, and improve reception characteristics. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a multipath search unit according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a multipath search unit of the CDMA receiver according to one embodiment of the present invention.

3A is a diagram illustrating an example of a weighting function used in one embodiment of the present invention, FIG. 3B is a diagram illustrating an example of a delay profile used in one embodiment of the present invention, and FIG. FIG. 2 is a diagram illustrating an output of the multiplier of FIG. 1.

FIG. 4 is a flowchart illustrating a processing operation of a multipath search unit according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a setting process of a weighting function by a state weighting unit in FIG. 2 ;

FIG. 6 is a flowchart illustrating a processing operation of a correlation peak position detection unit in FIG. 2 ;

FIG. 7 is a flowchart illustrating a maximum value search process performed by a correlation peak position detection unit in FIG. 2 ;

FIG. 8 is a flowchart illustrating a setting process of a weighting function by a state weighting unit according to another embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a multipath search unit of a CDMA receiver according to another embodiment of the present invention.

FIG. 10 is a flowchart illustrating a path replacement determination process of a path replacement determination unit in FIG. 9;

FIG. 11 is a flowchart illustrating a previous pass position protection operation according to another embodiment of the present invention.

FIG. 12 is a flowchart illustrating an operation of protecting a newly allocated path position according to another embodiment of the present invention;

FIG. 13 is a block diagram illustrating a configuration example of a conventional CDMA receiver.

FIG. 14 is a flowchart showing a conventional method of assigning multipaths to fingers.

[Explanation of symbols]

 Reference Signs List 1 DSP 5 Finger unit 6 Rake combining receiving unit 7 Sliding correlator 8 Delay profile power adding unit 11 Weighting unit 12 Multiplier 13 State weighting unit 14 Correlation peak position detecting unit 15, 17 Rake path allocating unit 16 Control memory 18 Path replacement judgment Department

Claims (11)

(57) [Claims] 1. A CDMA receiving apparatus including a plurality of fingers for despreading each one of paths and performing symbol synchronization, wherein a state weighting function calculated from a current assignment state to the plurality of fingers. Is calculated into a delay profile indicating a signal power distribution with respect to a delay time of a reception signal to the path, and a plurality of paths are searched after a level of a path currently assigned to the plurality of finger units is superior. CDMA characterized by the following:
Receiver. 2. The state weighting function is calculated for the delay profile corresponding to one of a new candidate path extracted in the search for the plurality of paths and a path currently assigned to the plurality of finger units. The CDMA receiver according to claim 1, wherein 3. A CDMA receiving apparatus including a plurality of fingers for despreading each path and synchronizing symbols with each other, wherein said plurality of fingers are assigned to said plurality of fingers based on a current assignment state to said plurality of fingers. Calculating means for calculating a state weighting function for making the level of the currently allocated path superior, and the state weighting function calculated by the calculating means to calculate a signal power distribution with respect to a delay time of a reception signal to the path. A CDM comprising: a calculating means for calculating a delay profile shown; and a searching means for searching a plurality of paths from a calculation result of the calculating means.
A receiving device. 4. The CDMA receiving apparatus according to claim 3 , further comprising an assigning unit that assigns a multipath detected by said searching unit to each of said plurality of finger units. 5. The delay unit according to claim 1, wherein the calculating unit adds the delay profile corresponding to one of a new candidate path extracted in the search for the plurality of paths and a path currently assigned to the plurality of finger units. CDMA receiver according to claim 3 or claim 4, wherein the configured to calculating the state weighting function. 6. A CDMA receiving apparatus including a plurality of finger sections for despreading each path and performing symbol synchronization by performing symbol despreading, wherein a delay profile indicating a signal power distribution with respect to a delay time of a received signal to the path is provided. A search unit for searching a plurality of paths; and a delay profile corresponding to one of a path of a new candidate extracted by the search unit and a path currently assigned to the plurality of finger units. Calculating a weighting function to make the level of the path currently assigned to the plurality of finger sections superior, and then assigning which of the new candidate path and the path currently assigned to the plurality of finger sections is to be assigned C having a determination means.
DMA receiver. 7. A multipath finger assignment method for a CDMA receiver including a plurality of finger units for despreading each one path and synchronizing symbols.
A state weighting function calculated from a current assignment state to the plurality of finger units is calculated to a delay profile indicating a signal power distribution with respect to a delay time of a reception signal to the path, and is currently assigned to the plurality of finger units. A multi-path finger assignment method, wherein a plurality of paths are searched after the level of a given path is superior. 8. A multipath finger assignment method for a CDMA receiving apparatus including a plurality of finger units for performing symbol despreading by performing despreading on one path each,
Calculating a state weighting function for giving priority to the level of a path currently allocated to the plurality of finger parts from the current allocation state to the plurality of finger parts; and calculating the calculated state weighting function. A multipath finger assignment method, comprising: calculating a delay profile indicating a signal power distribution with respect to a delay time of a reception signal to a path; and searching a plurality of paths from the calculation result. 9. The method according to claim 8 , further comprising the step of assigning a plurality of detected paths to each of said plurality of finger portions. 10. A CDMA system including a plurality of finger units for despreading each path and synchronizing symbols.
A method of allocating a multipath finger of a receiving apparatus, comprising: searching a plurality of paths from a delay profile indicating a signal power distribution with respect to a delay time of a received signal to the path; and a path of a new candidate extracted in the search. And calculating a weighting function set in advance to the delay profile corresponding to one of the paths currently assigned to the plurality of finger sections and the level of the path currently assigned to the plurality of finger sections. Deciding which of the path of the new candidate and the path currently allocated to the plurality of finger portions is to be allocated after the dominance. 11. A CDMA system including a plurality of finger units for despreading each path and synchronizing symbols.
A recording medium recording a finger assignment control program for causing a computer to perform multi-path finger assignment in a receiving apparatus, wherein the finger assignment control program causes the computer to provide a signal power with respect to a delay time of a reception signal to the path. A plurality of paths are searched from the delay profile indicating the distribution, and preset in the delay profile corresponding to one of a path of a new candidate extracted in the search and a path currently assigned to the plurality of finger units. Calculating the weighted function given to give priority to the level of the path currently assigned to the plurality of finger parts, and then assigning either the new candidate path or the path currently assigned to the plurality of finger parts. Finger assignment control program characterized in that A recording medium recording the beam.