JP2004312318A - Communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform effective path detection without widening a window range by a propagation path model in which a plurality of correlation peaks (paths) repeatedly appear/disappear at random positions. <P>SOLUTION: The detection range of the correlation peak is divided into a plurality of blocks. Then, it is assumed that two paths P0 and P1 of a B-D model are at the positions of -4 μs and -3 μs respectively, the leading path P0 is detected in the block #1 and the last path P1 is detected in the block #2. In this case, the center position of a group is obtained, a difference between the path group center position and the center position of a detection block is defined as a window control amount and window control is performed. Then, it is assumed that the path P0 disappears after 191ms and the path P0' newly appears at the position of 5 μs. Even in that case, the two paths P0' and P1 both stay inside the window at the same window position, and both can be detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication apparatus and a path detection method that are effective when applied to, for example, a DS-CDMA (Direct Sequence-Code Division Multiple Access) receiver.
[0002]
[Prior art]
Generally, when a mobile communication device using the CDMA system receives a scramble code transmitted from a base station and performs path detection control for performing synchronization determination, the mobile communication device corresponds to a preceding wave and a lagging wave in a multipath environment. Therefore, it is necessary to appropriately set a correlation peak (path) detection range in a correlation peak detection unit such as a matched filter.
The correlation peak detection range in this case is called a “window”. Even if the amount of path delay changes due to the influence of the propagation path, the window is set so that necessary peaks including the delay correlation peak can be detected within the window. (For example, see Patent Document 1).
[0003]
Further, in the DS-CDMA system, a propagation delay wave (delay path) is separated by using a spreading code, and a plurality of separated paths are efficiently combined to improve transmission quality.
This is a method called RAKE reception. Since the transmission quality can be improved as the number of propagation delay waves increases, it is particularly important for a DS-CDMA receiver to appropriately detect a propagation delay wave. .
More specifically, the DS-CDMA receiver detects a delay path using the correlation peak of the MF output of the received signal, and the MF output range serving as the detection range in this case is the above-described window. . Since the delay amount of the delay path changes in the state of the propagation path, it is necessary to detect the path by always following the window so that the delay path exists in the window.
[0004]
Therefore, a specific example of the conventional path detection method will be described next.
FIG. 3 is an explanatory diagram showing a specific example of a conventional path detection method. In the illustrated example, the window range is ± 8 μs, and a case where two paths are detected is shown.
First, a path group center position is obtained from the detected path position of the leading path P0 and the path position of the last path P1. The difference between the path group center position and the window center position is the window control amount. By controlling the window by this window control amount, the center of the window is located at the center of the path group, and the window can follow the path group.
[0005]
[Patent Document 1]
JP 2001-177440 A
[Problems to be solved by the invention]
By the way, a BD model (Birth-Death Model) is known as a propagation path model defined by 3GPP. This is a propagation path model in which two paths repeatedly appear and disappear one at a time at intervals of 191 ms at random positions within a range of ± 5 μs.
However, in the case of this BD model, the above-described path detection method shown in FIG. 3 has a problem that a delay path cannot be detected within the window range.
FIG. 4 is an explanatory diagram showing the problem of the conventional path detection method for the BD model by a specific example, and shows an example of the path position of the BD model and the window position where the path is detected.
First, as shown in FIG. 4A, it is assumed that two paths P0 and P1 of the BD model are located at positions of −4 μs and −3 μs, respectively. As a result of detecting the two paths, the window is controlled so that the center of the window is located at the center of the two paths.
However, after 191 ms, as shown in FIG. 4B, it is assumed that the path P0 at the position of −4 μs has disappeared and the path P0 ′ has newly appeared at the position of +5 μs.
In this case, at the window position in FIG. 4B, the path P1 can be detected within the window, but the path P0 'cannot be detected.
For this reason, conventionally, it is necessary to perform the path detection by expanding the window range, and there is a problem that the circuit scale increases.
[0007]
Therefore, an object of the present invention is to provide a communication apparatus capable of performing effective path detection without expanding a window range even in a propagation path model in which a plurality of correlation peaks (paths) repeatedly appear and disappear at random positions. And a path detection method therefor.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a correlation peak detection means for detecting a correlation peak from a received signal spread using a spreading code, and a correlation peak detection window for controlling a correlation peak detection window range in the correlation peak detection means. Control means, wherein the correlation peak detection window control means divides the correlation peak detection window range in the correlation peak detection means into an arbitrary number of blocks, and calculates a correlation peak value among the correlation peak values detected by the correlation peak detection means. , So that the center position between the detection position of the largest correlation peak value and the detection position of the next largest correlation peak value coincides with the center position of the two blocks where these two correlation peak values are detected. The detection window range is controlled.
[0009]
Further, in the embodiment, a correlation peak detection means for detecting a correlation peak from a received signal spread using a spreading code, and a correlation peak detection window control means for controlling a correlation peak detection window range in the correlation peak detection means Wherein the correlation peak detection window control means divides the correlation peak detection window range in the correlation peak detection means into an arbitrary number of blocks, and the correlation peak detection means Of the detected correlation peak values, the center position between the detection position of the largest correlation peak value and the detection position of the next largest correlation peak value is located at the center position of the two blocks where these two correlation peak values are detected. A communication device that controls the correlation peak detection window range so as to coincide with each other is disclosed.
[0010]
In the communication device and the path detection method according to the embodiment, when the correlation peak detection window control unit performs the correlation peak detection window control on the correlation peak detection unit, the correlation peak detection window range in the correlation peak detection unit is set to an arbitrary value. Of the correlation peak values detected by the correlation peak detection means, and the central position between the detection position of the largest correlation peak value and the detection position of the next largest correlation peak value is defined as the correlation between these two correlation peak values. The correlation peak detection window range is controlled so that the peak value coincides with the center position of the two detected blocks.
For this reason, even in a propagation path model in which a plurality of correlation peaks (paths) repeatedly appear and disappear at random positions, window control may be performed so that the correlation peaks (paths) remain in the window regardless of the appearance and disappearance of each correlation peak. This makes it possible to perform effective path detection without expanding the window range.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a communication device and a path detection method thereof according to the present invention will be described.
FIG. 1 is a block diagram illustrating a configuration example of a receiving unit of a communication device described in an embodiment of the present invention.
As shown, the communication device includes a matched filter 101, a profile 102, a memory 103, a scramble code generator 104, and a control unit 105.
[0012]
Matched filter 101 receives a received baseband signal of a pilot channel from a receiving unit (not shown), and reverses the received baseband signal using a scramble code (here, a common short code) generated by scramble code generator 104. This is an example of correlation peak detection means.
In this case, the matched filter 101 performs a correlation operation for one symbol time between the received baseband signal of the pilot channel and the scramble code using a multiplier and an accumulator.
If the phase of the scramble code of the received baseband signal of the pilot channel matches the phase of the scramble code output from scramble code generator 104, matched filter 101 detects a sharp correlation peak unique to the scramble code. In the case of a multipath environment, a correlation peak that is time-shifted by the delay time appears in the output of the matched filter 101 for the delayed wave.
[0013]
The profile 102 removes phase fluctuation by squaring the output of the matched filter 101.
That is, since the output of the matched filter 101 has a phase rotation due to the propagation path and the information signal, the phase fluctuation is removed from the profile 102.
Also, the profile 102 removes noise included in the output of the matched filter 101 by cumulatively averaging the output of the matched filter 101 from which the phase fluctuation has been removed in the memory 103, and obtains the maximum value and the average value from the cumulative averaging output. Thus, for example, a value obtained by adding an average value to a half of the maximum value is set as a threshold, and an average output exceeding the threshold is set as a reaching wave, that is, a reception path timing, and is output.
In this case, the memory 103 has an area corresponding to the window width.
Then, the matched filter 101 and the profile 102 obtain pass timing corresponding to the window width.
[0014]
The control unit 105 supplies a symbol timing control signal to the matched filter 101 to control the symbol timing of the matched filter 101. The control unit 105 performs a process based on the following path detection method, and detects a correlation peak in the matched filter 101. It has a function as a correlation peak detection window control means for controlling the window range.
That is, the control unit 105 of the present example divides the correlation peak detection window range of the matched filter 101 into an arbitrary number of blocks, and detects the position of the largest correlation peak value among the correlation peak values detected by the matched filter 101. By controlling the correlation peak detection window range so that the center position between the two correlation peak values and the detection position of the next largest correlation peak value coincides with the center position of the two blocks where these two correlation peak values are detected. Even in a propagation path model such as a BD model, effective path detection can be performed without expanding a window range.
In addition, various methods can be adopted for dividing the window into blocks. For example, a method in which a simulation or the like is performed in advance and an optimal dividing method is appropriately set according to a communication environment or the like is appropriately set. Can be used. Each divided block is appropriately numbered and managed.
[0015]
FIG. 2 is an explanatory diagram showing a specific example of the path detection method in this example, and shows the path detection method in the BD model.
First, as shown in FIG. 2A, it is assumed that the two paths P0 and P1 of the BD model are located at positions of -4 .mu.s and -3 .mu.s, respectively, and the window position at that time is at the illustrated position.
Here, the first path P0 is detected in block # 1, and the last path P1 is detected in block # 2. Therefore, the control unit 105 controls the window so that the path remains in the block where the first path and the last path are detected.
For example, the center position of the path group is determined from the path position of the leading path P0 and the path position of the last path P1 of the detected path group, and the difference between this path group center position and the center position of the detection block is set as the window control amount. Perform control.
Next, suppose that after 191 ms, as shown in FIG. 2B, the path P0 at the position of −4 μs disappears and the path P0 ′ newly appears at the position of +5 μs. However, even in this case, at the window position shown in FIG. 2B, both paths P0 ′ and P1 remain in the window, and both can be detected.
[0016]
As described above, in the present example, the path detection window range is divided into blocks, and the difference between the center position of the plurality of paths and the center position of the block in which each path is detected is used as the window control amount. Can be effectively dealt with, and appropriate path detection can be performed without expanding the window range.
In the above description, the case where two paths are detected has been described. However, the present invention can be similarly applied to the case where more path groups are detected. In this case, the detection of the largest correlation peak value is performed. Window control is performed by obtaining a window control amount from the difference between the center position between the position and the detection position of the next largest correlation peak value, and the center position of the two blocks where these two correlation peak values are detected.
In the above example, an example in which a BD model is used as a channel model has been described. However, the present invention can be applied to other channel models requiring similar control. Further, the present invention can be widely applied to various types of communication systems.
[0017]
【The invention's effect】
As described above, in the present invention, when the correlation peak detection window control unit performs the correlation peak detection window control on the correlation peak detection unit, the correlation peak detection window range in the correlation peak detection unit is divided into an arbitrary number of blocks. Of the correlation peak values detected by the correlation peak detection means, the center position between the detection position of the largest correlation peak value and the detection position of the next largest correlation peak value is determined by the two correlation peak values being detected. Since the correlation peak detection window range is controlled so as to coincide with the center position of two blocks, even in a propagation path model in which a plurality of correlation peaks (paths) repeatedly appear and disappear at random positions, each correlation peak is detected. Window control can be performed so as to stay in the window regardless of the appearance / disappearance of peaks, enabling effective path detection without expanding the window range It can be carried out to become.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a receiving unit of a mobile communication device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a specific example of a path detection method according to the embodiment shown in FIG. 1;
FIG. 3 is an explanatory diagram showing a specific example of a conventional path detection method.
4 is an explanatory diagram showing a problem when the conventional path detection method shown in FIG. 3 is applied to a BD model.
[Explanation of symbols]
101 matched filter, 102 profile, 103 memory, 104 scramble code generator, 105 control unit.

Claims (1)

Correlation peak detection means for detecting a correlation peak from a received signal spread using a spreading code, and a correlation peak detection window control means for controlling a correlation peak detection window range in the correlation peak detection means,
The correlation peak detection window control means divides the correlation peak detection window range in the correlation peak detection means into an arbitrary number of blocks, and sets the largest correlation peak value among the correlation peak values detected by the correlation peak detection means. The correlation peak detection window range is controlled so that the center position between the detection position of the second correlation peak value and the detection position of the next largest correlation peak value coincides with the center position of the two blocks where these two correlation peak values are detected. ,
A communication device characterized by the above-mentioned.

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