JP3267264B2 - Moving speed detecting method and apparatus in spread spectrum communication - Google Patents

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 body 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 for indicating the allocation process for each finger, a combiner for combining the outputs of said plurality of fingers, a reception apparatus of a spread spectrum communication system comprising a signal processing unit, further control of the apparatus radio unit
Wireless control unit that performs
The frame is sent from the radio section control section to the signal processing section.
The timing indicating the head is input, and the signal processing unit
The head timing of the frame from the radio control unit,
Path of the maximum correlation value notified from the path selector or
One of the path timings of the value obtained by subtracting a predetermined value from the maximum correlation value
Time difference between the two and the change in the time difference per unit time.
Calculated amount, and a predetermined moving speed determination threshold
A comparison is made between the amount of change in the time difference and the level of the moving speed of the mobile station.

[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 improves 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/69-1/713 H04J 13/00-13/06 H04Q 7/34

Claims (2)

(57) [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 combiner for combining the outputs of said plurality of fingers, a reception apparatus of a spread spectrum communication system comprising a signal processing section, further apparatus wirelessly
Control system to maintain frame timing
Control unit, and the radio unit control unit sends a signal to the signal processing unit.
A timing indicating the start of a frame is input, and the signal processing unit sends a start of a frame from the radio unit control unit.
Head timing and maximum phase notified from the path selector
Function value path or a value obtained by subtracting a predetermined value from the maximum correlation value.
Time difference from one of the timings of the
Calculate the amount of change per unit time and move in advance
A spread-spectrum communication apparatus characterized in that the speed of a mobile station is determined by comparing a speed determination threshold value with the amount of change in the time difference . 2. A searcher for inputting a received signal and separating it at a resolution of one chip or less, and a selector for each path,
Path selection instructing the assignment processing of each finger of the number of fingers
Selector and a combiner for combining outputs of the plurality of fingers
Spread spectrum communication system including a signal processing unit
Method of Detecting Moving Speed of Mobile Station in Various Receivers
Te, (a) in the signal processing unit, the line control unit radio section
From the wireless controller that holds the timing of the new frame
Receives the timing indicating the beginning of the frame to the signal processing unit
And (b) the head timing of the frame from the radio control unit.
And the path of the maximum correlation value notified from the path selector is also
Or the timing of the path with a value obtained by subtracting a predetermined value from the maximum correlation value
Time difference with one of the
(C) calculating a predetermined moving speed determination threshold value and the time.
Comparing the amount of change in the time difference ; and (d) comparing the amount of change in the time difference with the threshold value or more.
The rewritable determined can mobile station and fast, of the said time difference
When the amount of change is smaller than the threshold, the mobile station is slowed down.
Moving speed detection method for a mobile station, characterized in that it comprises, determining a.