JP2000252959A - Method and device for detecting moving speed in spread spectrum communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for moving speed detection in spread spectrum communication which realize a service like a hierarchical cell constitution based on calculation of the moving speed of a mobile station by using a searcher to calculate the moving speed of the mobile station. SOLUTION: A reception equipment in a spread spectrum communication system includes a searcher 1 which takes a reception signal as the input to separate it with a resolution smaller than one chip, a selector 3, plural fingers 41 to 4n, a path selector 2 which indicates assignment processing of each path and each finger to the selector 3, a synthesizer 5 which synthesizes outputs of plural fingers, and a signal processing part 6. The signal processing part 6 calculates the relative delay quantity difference between two timings, which are delay quantities of upper two paths indicating a maximum correlation value, and the relative delay quantity variation per unit time in accordance with information from the path selector 2, and the relative delay quantity variation per unit time is compared with a preliminarily determined threshold to discriminate whether the moving speed of the mobile station is high or low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication technique, and more particularly, to a moving speed detecting method and apparatus.

[0002]

2. Description of the Related Art Recently, the number of subscribers in a mobile communication system such as a mobile phone has been remarkably increased. In such a situation, in order to provide a service, it is necessary to further improve the frequency use efficiency.

One of the measures for improving the frequency utilization efficiency is a hierarchical cell configuration in which a macro cell having a large cell radius and a micro cell having a small cell radius are arranged in an overlapping manner.

[0004] This is because the macro cell is mainly used when moving at a high speed or in a low traffic area such as a suburb, and is mainly used for a low-speed moving object in a high traffic area such as a downtown area. Is to dispose microcells and make macro / microcells coexist, thereby improving the effective use of frequency and increasing the subscriber accommodating capacity.

[0005]

In the study of the hierarchical cell structure, detection of the speed of a moving body is a heavy technique.

On the other hand, PD, which is a current mobile phone system,
C (Personal Digital Cellular Telecommunication
System (CDMA) as the next generation system
2. Description of the Related Art A communication system using a spread spectrum technique such as a vision multiple access (code division multiple access) scheme has been studied.

In recent years, while the number of mobile phone subscribers has been increasing remarkably, if the speed of a moving object can be detected by using a technique unique to spread spectrum, a hierarchical cell configuration can be realized even in a system using spread spectrum. And the frequency can be used effectively.

[0008] Spread spectrum communication is a modulation method that makes the bandwidth of a signal after modulation far wider than that obtained by narrow-band modulation, unlike a normal narrow-band modulation method. Such spread spectrum communication has various features and advantages not found in narrowband communication.

[0009] In mobile communication, radio waves emitted from a radio base station are reflected by many buildings before reaching the mobile station.
A multi-wave propagation path (multi-path) is formed by being subjected to diffraction and scattering. One of the advantages of spread spectrum communication is that the multi-path can be separated and a path diversity effect can be expected. . This is "RAKE reception"
This is because a delay profile for each path of a signal received in a multipath environment can be obtained. To realize this, the radio base station and mobile station used for spread spectrum communication include:
A function called a searcher is provided to calculate a delay profile for each path.

[0010] Therefore, the present invention has been made based on the recognition of the above problems, and an object of the present invention is to calculate the moving speed of a mobile station using a searcher. It is an object of the present invention to provide a method and an apparatus for detecting a moving speed in spread spectrum communication, which enable services such as a type cell configuration. Things.

[0011]

In order to achieve the above object, the present invention provides a searcher for inputting a received signal and separating it at a resolution of one chip or less, a selector, a plurality of fingers, and a path for each of the selectors. And a path selector that instructs the assignment processing of each finger, a combiner that combines the outputs of the plurality of fingers, and a receiving device of a spread spectrum communication system including a signal processing unit, wherein the signal processing unit is From the information from the path selector, the top 2 indicating the maximum correlation value
The relative delay difference between the two timings, which is the delay amount of the path,
And calculate the relative delay amount change per unit time, the relative delay amount change per unit time, by comparing with a predetermined threshold, to determine the level of the mobile station moving speed, It is characterized by the following.

[0012]

Embodiments of the present invention will be described. FIG. 1 is a diagram showing a configuration of a RAKE receiver according to an embodiment of the present invention. Referring to FIG. 1, a searcher 1 separates a received signal input from an antenna (not shown) into multipaths with a resolution of one chip or less.
According to the instruction of the path selector 2, the selector 3 allocates one finger among the fingers 41 to 4n for each path. Of course,
If the number of passes is large, the number of fingers to be allocated will increase. The outputs of the fingers 41 to 4n are combined by the combiner 5 and output as a demodulated signal.

In one embodiment of the present invention, the signal processing unit 6
Calculates the relative delay (time) change per unit time from the relative delay (time) difference between the two paths having the highest correlation value, and uses it for calculating the moving speed of the mobile station. This utilizes the characteristic that the delay profile is constant when the mobile station is stopped, and changes when the mobile station starts moving. Hereinafter, the present invention will be described in detail with reference to examples.

[0014]

FIG. 1 is a diagram showing a configuration of a RAKE receiver according to one embodiment of the present invention. Referring to FIG. 1, the RAKE receiver according to the present embodiment includes a searcher 1 capable of separating a received signal input from an antenna with a resolution of one chip or less, a selector 3, and each path and each finger for the selector 3. 4
A path selector 2 for instructing allocation processing of 1 to 4n, a synthesizer 5 for synthesizing the outputs of the fingers 41 to 4n, and a relative delay (time) difference of two waves with the maximum correlation value based on the information of the path selector 2. A signal processing unit 6 for calculating a relative delay amount (time) change amount per unit time and determining a moving speed of the mobile station; and a memory 7 used as a storage unit of the signal processing unit 6. Have been.

The operation of each unit will be outlined below.

The searcher 1 includes a matched filter prepared for each fixed delay amount (time) of one chip or less, and when a received signal is continuously input, the output of the searcher 1 is output for each fixed delay amount (time). Is output as the correlation value.

A fixed delay amount (time) by the path selector 2
Is derived, and based on the results,
The path selector 2 specifies a fixed delay amount (time) and a finger to be used for the selector 3.

According to an instruction from the path selector 2, the selector 3 opens a path to the finger with a specified fixed delay amount (time).

The path selector 2 outputs, to the signal processing unit 6, two paths having the maximum correlation value in the obtained delay profile together with the fixed delay amount.

The signal processing unit 6 calculates a relative delay (time) difference between the two paths and a relative delay (time) change per unit time from the information received from the path selector 2,
This is compared with a threshold value to determine whether the moving speed of the mobile station is high or low, and notifies the central processing unit (not shown) of the device.

Next, a specific operation of the embodiment of the present invention will be described.

Since mobile communication uses radio communication, a plurality of propagation paths exist in a radio section. FIG. 2 is a diagram illustrating a multipath, in which a radio wave emitted from a mobile station (MS) passes through three propagation paths, not only a direct wave (path 1) but also reflected waves (path 2 and path 3). FIG. 2 is a diagram schematically illustrating a state of arriving at a wireless base station (BS).

In spread spectrum communication, such paths can be separated by a RAKE receiver and received respectively.

As described above, the searcher 1 includes a matched filter prepared for each fixed delay amount (time) of one chip or less, and outputs a correlation value for each fixed delay amount when a continuous received signal is input. The path selector 2 forms a delay profile as shown in FIG. FIG. 3 is a diagram illustrating an example of the delay profile. The horizontal axis indicates the fixed delay amount (time), and the vertical axis indicates the correlation value.

In the example shown in FIG. 3, it can be seen that at timings T1, T2 and T3 at which the correlation values show peaks, there are paths that are considered to be effective for allocating fingers. Normally, a condition that is determined to be effective for allocating a finger is a path having a correlation value obtained by subtracting a specified value from the path indicating the maximum correlation value.

The path selector 2 determines to use the finger 1 at the timing T1, the finger 2 at the timing T2, and the finger 3 at the timing T3 in FIG.

The path selector 2 determines the timings T1 and T2, which are the delay amounts of the upper two paths showing the maximum correlation value,
Notify the signal processing unit 6.

FIG. 4 is a diagram showing an example of the contents stored in the memory 7 accessed by the signal processing section 6.

In the signal processing unit 6, the relative delay difference T (= | T1-T2 |), which is the difference between the two delay amounts, from the timings T1 and T2 notified from the path selector 2, and the per unit time The change amount δ of T (= T / Δt) is calculated, and the relative delay difference T and the change amount δ of T per unit time are stored in the memory 7.

Further, the memory 7 stores and holds a threshold value C for determining the moving speed of the mobile station.

FIG. 5 is a flowchart showing a processing flow of the signal processing section 6 in one embodiment of the present invention. Signal processing unit 6
Then, the change amount δ of T per unit time is calculated from the relative delay amount difference T (step 101), and the moving speed determination threshold value C is compared with the change amount δ of T (step 102), and C ≦
If δ, the moving speed of the mobile station is determined to be high (step 103). If C> δ, the moving speed of the mobile station is determined to be low (step 104), and the determination result is sent to the central processing unit of the apparatus. Notification is made (step 105).

In the central processing unit of the apparatus, a corresponding service (for example, a hierarchical cell configuration or the like) is performed based on the speed information of the mobile station.
To perform the following.

Next, a second embodiment of the present invention will be described. In the above embodiment, the moving speed of the mobile station is determined on the assumption that there are two or more paths. For this reason, when there is only one path, such as in an area where a multipath is unlikely to exist, such as in a suburb, the moving speed is always determined to be low. Second embodiment of the present invention
The embodiment of the present invention is an improvement of the above-described embodiment, and solves this problem.

In the spread spectrum communication, the radio base station
Each mobile station has an information unit called a "frame" having a temporal periodicity. The frames are synchronized between the radio base station and the mobile station by the amount of the radio wave propagation delay time, and both the radio base station and the mobile station transmit control and information in frame units.

FIG. 6 is a diagram schematically showing a state of frame transmission between a radio base station and a mobile station. The transmission frame 1 from the radio base station is defined as the reception frame 1 of the mobile station, and the transmission frame 1 and the reception frame 1 have a radio wave propagation delay difference.

FIG. 7 is a diagram showing the configuration of the second embodiment of the present invention. The configuration of the above-described embodiment shown in FIG. In the second embodiment of the present invention, the searcher 1, the path selector 2, the selector 3, the fingers 41 to 4n, and the combiner 5 are the same as those in the embodiment shown in FIG. Omitted.

The radio section controller 8 controls the radio section of the apparatus, and holds the timing of a frame.

The radio section control section 8 inputs a timing representing the beginning of a frame to the signal processing section 61.

The signal processing unit 61 calculates a time difference T ′ between the head timing of the frame from the radio unit control unit 8 and T1 (T2) notified from the path selector 2, and a T ′ change amount δ ′ per unit time. It is calculated and stored in the memory 71. The timing used here may be either T1 or T2.

FIG. 8 is a diagram showing an example of the contents stored in the memory 71 in the second embodiment of the present invention. Referring to FIG. 8, the relative delay amount difference, the change amount δ of the relative delay amount difference per unit time, the difference T ′ between the frame head timing and T1 (T2), the change amount δ ′ of T ′ per unit time, A mobile station moving speed determination threshold C is provided.

FIG. 9 is a flowchart showing a processing flow of the signal processing section 61 according to the second embodiment of the present invention. Signal processing unit 6
1 calculates a time difference T 'between the head timing of the frame from the radio unit controller 8 and T1 (T2) notified from the path selector 2, and a T' change amount δ 'per unit time (step 201). Then, the moving speed determination threshold C is compared with the change amount δ ′ (step 202), and if C ≦ δ ′,
The moving speed of the mobile station is determined to be high (step 203),
If C> δ ', it is determined that the speed is low (step 2).
03), and notifies the result of the determination to the central processing unit in the apparatus (step 204).

[0042]

As described above, according to the present invention,
The following effects are obtained.

The first effect of the present invention is that it is not necessary to implement new hardware for detecting the moving speed. The reason is that the RAKE receiver is a function normally provided in spread spectrum communication, and the present invention is realized by using the function.

The second effect of the present invention is to determine whether to use the judgment on the mobile communication system side, or on the mobile station side, or both in implementing the present invention. That is, since the user (mobile communication carrier) can freely set the functions, the functions of the system can be shared.

The reason is that the RAKE receiver is a function provided in each of the radio base station and the mobile station.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram for explaining one embodiment of the present invention;
FIG. 3 is a diagram for explaining an example of a multipath.

FIG. 3 is a diagram for explaining one embodiment of the present invention;
FIG. 4 is a diagram illustrating an example of a delay profile.

FIG. 4 is a diagram showing an example of storage contents of a memory according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a processing flow of a signal processing unit in one embodiment of the present invention.

FIG. 6 is a diagram for explaining one embodiment of the present invention;
FIG. 3 is a diagram illustrating a state of frame transmission between a wireless base station and a mobile station.

FIG. 7 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 8 is a diagram showing an example of contents stored in a memory according to another embodiment of the present invention.

FIG. 9 is a flowchart showing a processing flow of a signal processing unit according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 searcher 2 path selector 3 selector 41 to 4n finger 1 to finger n 5 combiner 6, 61 signal processing unit 7, 71 memory 8 radio unit control unit

[Procedure amendment]

[Submission date] May 15, 2000 (2000.5.1)
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[Procedure amendment 1]

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[Correction target item name] Claim 1

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[Correction target item name] Claim 3

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[Correction target item name] Claim 4

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[Correction method] Change

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[0011]

Means for Solving the Problems The present invention to achieve the above object, a searcher for separating at inputs the received signal 1 chip resolution below, a selector, a plurality of fingers, fixed
Deriving the delay profile of the correlation value with respect to the delay amount
A spread spectrum communication apparatus including: a path selector that instructs the selector to perform a process of assigning each path and each finger based on a result ; a combiner that combines outputs of the plurality of fingers; and a signal processing unit. The path selection unit acquires
Of the highest correlation value in the delay profile
Output to the signal processor together with the fixed delay amount.
And force, the signal processing unit, the path notified from the selector, wherein the timing is a delay of a predetermined number of upper path the maximum correlation value in the delay profile, the relative delay amount difference, and the unit time Calculating the relative delay amount change amount per unit time, and comparing the relative delay amount change amount per unit time with a predetermined threshold value to determine the level of the moving speed of the mobile station. And

Claims (5)

[Claims] A searcher for inputting a received signal and separating the received signal at a resolution of one chip or less; a selector; a plurality of fingers; and a path selector for instructing the selector to assign each path and each finger. A spreader communication apparatus including a combiner that combines outputs of the plurality of fingers, and a signal processing unit, wherein the signal processing unit is notified from the path selector and indicates a highest correlation value. The relative delay amount difference and the relative delay amount change per unit time are calculated from the timing that is the delay amount of the predetermined number of paths, and the relative delay amount change per unit time is calculated as a predetermined threshold value. A spread spectrum communication apparatus for determining whether the moving speed of the mobile station is high or low by comparing the mobile station with the mobile station. 2. A searcher for inputting a received signal and separating the received signal at a resolution of one chip or less, a selector, a plurality of fingers, and a path selector for instructing the selector to assign each path and each finger. A receiving device for a spread spectrum communication system including a combiner for combining outputs of the plurality of fingers, and a signal processing unit, further comprising a wireless control unit for controlling a device wireless unit and holding a frame timing. A timing representing the beginning of a frame is input from the radio unit control unit to the signal processing unit, and the signal processing unit transmits a frame start timing from the radio unit control unit and a maximum correlation notified from the path selector. Calculate the time difference from one of the timings of the value path or the value of the path obtained by subtracting a predetermined value from the maximum correlation value, and the amount of change in the time difference per unit time. And, by comparing the moving speed determining threshold predetermined amount of change in the time difference, determines the level of the moving speed of the mobile station, the spread spectrum communication apparatus characterized by. 3. In a communication system using spread spectrum, means for calculating and outputting a predetermined amount of path delay, and using the predetermined number of path delays to calculate a delay difference and Means for calculating a change amount of the delay amount difference per unit time; and a means for comparing the change amount of the delay amount difference with a predetermined threshold value to determine a moving speed of the mobile station. Spreading communication system. 4. A searcher for inputting a received signal and separating it at a resolution of one chip or less, a path selector for instructing a selector to assign each path and a plurality of fingers to each finger, and a plurality of said plurality of fingers. In a method for detecting a moving speed of a mobile station in a receiving apparatus of a spread spectrum communication system including a combiner for combining outputs of fingers and a signal processing unit, (a) the signal processing unit is notified from the path selector Calculating the relative delay amount difference and the relative delay amount change amount per unit time from the timing that is the delay amount of the predetermined number of upper paths indicating the maximum correlation value; and (b) calculating the relative delay amount per unit time. Comparing the delay amount change amount with a predetermined threshold value; and (c) determining that the mobile station is fast when the relative delay amount change amount is equal to or greater than the threshold value. Moving speed detection method for a mobile station relative delay variation is characterized in that it comprises, determining that slow the mobile station when the small than the threshold value. 5. A searcher for inputting a received signal and separating it at a resolution of one chip or less, a path selector for instructing a selector to assign each path and a plurality of fingers, and said plurality of fingers. A synthesizer that synthesizes the output of
A method of detecting a moving speed of a mobile station in a receiving device of a spread spectrum communication system including a signal processing unit, comprising: (a) a wireless control unit that controls a device wireless unit and holds a frame timing in the signal processing unit; Receiving a timing representing the beginning of a frame to the signal processing unit; and (b) a predetermined value based on the beginning timing of the frame from the radio unit control unit and the path of the maximum correlation value or the maximum correlation value notified from the path selector. Calculating a time difference between the subtracted value and one of the timings of the path, and a change amount per unit time of the time difference; and (c) a predetermined moving speed determination threshold value and a change amount of the time difference. And (d) determining that the mobile station is high speed when the change amount of the time difference is equal to or greater than the threshold value, Determining the speed of the mobile station as low speed when the amount of change in the time difference is smaller than the threshold value.