JP2799537B2 - Mobile communication reception level detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a mobile communication reception level detection system for mobile communication. In particular, the present invention relates to a method for calculating an averaged reception level in a mobile communication reception level detection method.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a car telephone system. FIG. 7 is a diagram showing the fluctuation of the reception electric field of the mobile communication system. FIG. 8 is a diagram for explaining the averaging of the reception level by the conventional mobile communication reception level detection method of the traveling averaging method and the block averaging method, and FIG. 8A shows the fluctuation of the intensity of the reception electric field. FIG. 8B is a diagram for explaining the averaging of the reception level by the running averaging method, and FIG. 8C is a diagram for explaining the averaging of the reception level by the blocking averaging method.
FIG. 9 is a diagram showing detection results for a sudden change in the reception level of the running average averaging method and the block averaging method of the conventional mobile communication reception level detection method, and FIG. FIG. 9B shows the detection result of the block averaging method.

[0003] In FIG. 6, an automobile telephone system, the mobile communication control station 20, the base station 30 ₁ to 30 _I, composed like the mobile station 40 and the radio zone 50 ₁ to 50 _I. The mobile station 40 measures the electric field intensity level E _i of the radio wave transmitted from each base station 30 _{j at a} different frequency f _i in order to determine the serving wireless zone 50, and determines the maximum reception level (here, The base station of E _j ) (here, 30 _j ) is determined to be within the area of the visited zone.

On the other hand, in mobile communication, it is generally rare that a base station and a mobile station can directly see through. Since radio waves are reflected and diffracted by buildings, terrain, etc., they travel in an automobile or the like as shown in FIG. While receiving radio waves, its characteristics are subject to very deep fading of several tens of dB.
In order to accurately determine the serving wireless zone in such a fading environment, instantaneous electric field strength level values are compared and the determining of the serving wireless zone is not performed, as shown in FIG. In general, a method is used in which a field strength level is sampled on a time axis, and a plurality of the field strength levels are averaged to calculate a field strength level value, which is used for determining a wireless zone in which the mobile station is located. For example, car phone, Chapter 5, supervised by Moriya Kuwahara,
It is described in detail in IEICE and Mobile Communications, Chapter 11, edited by Masaaki Shinji, Maruzen.

In this case, when the measurement accuracy and the readiness of detection are taken into consideration, a method using a running average method (running average) as shown in FIG. 8B is generally used.
However, in this method, it is necessary to prepare at least the number of buffer memories necessary for accumulating the sampled values (hereinafter referred to as m) corresponding to the averaged number. Here, when the number of base stations whose level is measured is N, at least N × m buffer memories are required.

On the other hand, as a method for reducing the buffer memory as much as possible, as shown in FIG. 8 (c), a block averaging method in which m receptions are added for each block and the reception level is calculated by averaging every measurement number m. There is. In this method, it is sufficient to prepare one buffer memory corresponding to the base station (or frequency) and to add the buffer memory for each sample. Therefore, it is sufficient to prepare at least one buffer memory in the base station.
However, in this method, since the calculation result of the reception level can be output only every measurement number m, responsiveness to a sudden change as shown in FIG. 9 may not be expected.

As one of the methods of reducing the buffer memory as much as possible and outputting the calculation result of the reception level for each sample, a calculation method of the reception level standardized in the next North American digital car telephone system (hereinafter referred to as a buffer saving method). A memory-type averaging method has been proposed. The outline is shown below.

The number of times of measurement averaging is m. The sampling values of the m electric field strength levels are represented by F (1), F (2),.
Assuming that F (m), the first average value F _ave is obtained as follows.

F _ave (1) = [F (1) + F (2) +...
+ F (m)] / m When the (m + 1) -th sample value is obtained, the next average value F
_{Find ave} (2).

F _ave (2) = F _ave (1) + [F (m + 1) −F _ave (1)] / m (m + 2) and thereafter, the same processing as the above calculation method is performed.

[0011]

However, in such a conventional mobile communication reception level detection system, in the case of the running averaging method, it is necessary to increase the number N of base stations or increase the number m of averaging. In some cases, there is a problem that the load is particularly large in a mobile phone or the like having only a limited buffer memory.

In the case of the block averaging method, when it is necessary to detect a rapid change, a large detection delay (maximum mx (Interval between samples).

FIG. 10 is a view showing a detection result of a buffer-saving memory type detection method of a conventional mobile communication reception level detection method. In the case of the buffer-saving memory type averaging method, this method can cope with the number of base stations with one buffer memory. On the other hand, in order to refer to an infinite past level value as a calculation history of averaging, FIG. There is a problem in that the detection accuracy is extremely deteriorated as compared with the running averaging method, because the detection accuracy is particularly weak against such a rapid level change.

The present invention solves the above problems,
It is an object of the present invention to provide a mobile communication reception level detection method capable of following a sudden reception level change by minimizing a buffer memory required for averaging.

[0015]

SUMMARY OF THE INVENTION The present invention relates to a mobile communication reception level detection system comprising detection means for discretely detecting a reception level and outputting the reception level value. And a block averaging means for averaging a predetermined number in block units to create a block average value and outputting the block average value, and adding the reception level value each time the reception level value is input from the start of detection, and inputting the reception level value Receiving level averaging means for subtracting the block average value of the block immediately before the operation, dividing by the predetermined number, and outputting the result as an averaged receiving level.

[0016]

The reception level value is averaged in units of a predetermined number of blocks from the start of detection, and is stored in a buffer memory and sequentially updated, and added each time the reception level value is input from the start of detection. By subtracting the block average value of the block immediately before inputting the reception level value and dividing by a predetermined number to obtain an averaged reception level, one buffer memory for storing the block average value is provided for each base station. Since it is only necessary and only the immediately preceding block average value is affected, the buffer memory required for averaging the buffer memory is reduced as much as possible, and it is possible to follow a sudden change in the reception level.

[0017]

Embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, the mobile communication reception level detection system includes detection means 1 for discretely detecting a reception level and outputting a reception level value 6 thereof.

Here, a feature of the present invention is that a block averaging means 2 for averaging a predetermined number of reception level values 6 in units of blocks from the start of detection to generate a block average value 7 and outputting the block average value 7 for each block. Is added each time the reception level value 6 is input from the start of detection, the block average value 7 of the block immediately before the reception level value 6 is input is subtracted, and the result is divided by a predetermined number m to obtain an averaged reception level 8 An addition means 3, a subtraction means 4, and a reception level averaging means 5 are provided as the reception level calculation means for outputting as.

The operation of the mobile communication reception level detection system having such a configuration will be described.

FIG. 2 is a diagram showing a reception level calculation method of the mobile communication reception level detection system according to the present invention. FIG. 3 is a flowchart showing the processing of the mobile communication reception level detection method of the present invention. FIG. 4 is a diagram showing a detection result with respect to a rapid change of the reception level in the mobile communication reception level detection system of the present invention. FIG. 5 is a diagram showing a comparison between the detection result of the mobile communication reception level detection method of the present invention and the detection results of the running averaging method and the buffer saving type averaging method.

In FIGS. 2 and 3, the average number of measurements is m (here, m is 5). The block average value is B
_ave . Now, m reception level values (sample values) are represented by F
Assuming (1), F (2),..., F (m), the first averaged reception level F _ave (m) and the average value of the first m blocks B _ave are obtained as follows.

SUM = F (1) + F (2) +... + F (m) (1) F _ave (m) = SUM / m (2) B _ave = SUM / m (3) (m + 1) th reception level When the value F (m + 1) is obtained, the next block average value F _ave (m + 1) is obtained as in the following equation.

SUM = SUM + F (m + 1) −B _ave (4) F _ave (m + 1) = SUM / m (5) When the (m + 2) th reception level value F (m + 2) is obtained, similarly, the averaged reception level F _{Find ave} (m + 2).

SUM = SUM + F (m + 2) −B _ave (6) F _ave (m + 2) = SUM / m (7) The same processing as described above is performed for the (m + 3) th and thereafter. (M + m) -th (2m-th) reception level value F (2
When m) is obtained, the m block average values B _ave are updated as follows.

B _ave = SUM / m (8) Next, the above and the above are repeatedly executed. That is,
When the (2m + 1) -th reception level value F (2m + 1) is obtained, the next averaged reception level F _ave (2m + 1) is obtained as follows.

SUM = SUM + F (2m + 1) −B _ave (9) F _ave (2m + 1) = SUM / m (10) When the (2m + 2) -th reception level value F (2m + 2) is obtained, similarly, the average value F _ave ( 2m + 2).

[0028] SUM = SUM + F (2m + 2) -B ave F ave (2m + 2) = SUM / m even (2m + 2) th received level value F (2m + 2) after the same processing. The feature of the present invention is that, as can be seen from equation (8), the SUM at the time when the 2m-th reception level value F (2m) is obtained is given by SUM = F (1) according to equations (1) and (3). ) + ... + F (m) + ... + F (2m) -m
× B _ave = F (m + 1) +... + F (2m) That is, it can be seen that the equation (8) in which the block average value B _ave is updated is no longer affected by F (1) +... + F (m). Therefore,
Only the last block average is affected by the measurement. As a result of performing such an operation, as shown in FIG. 4, if the block averaging period is the same, the same result as in the case of using the running averaging method can be obtained for a sudden change, for example.

FIG. 5 shows a result calculated by actual fading. The horizontal axis indicates time, and the vertical axis indicates the averaged reception level. In FIG. 5, when the running averaging method is set to a true value, the present invention has almost the same characteristics as the running averaging method with respect to normal fluctuations, Although the characteristics are slightly inferior to those of the averaging method, the characteristics are far superior to those of the buffer-saving memory type averaging method.

As described above, according to the present invention, the buffer averaging method for storing the block average value for each number of base stations can be dealt with only by adding one extra buffer memory to the conventional block averaging method. The buffer memory can be greatly reduced compared to

In this embodiment, the adding means, the subtracting means, the receiving level averaging means and the like have been described as different blocks, but the adding means, the subtracting means and the receiving level averaging means need not be different blocks. The circuit means capable of substantially calculating the averaged reception level can be variously configured so that the present invention can be implemented.

Although the present invention has been described with respect to the method of averaging the reception level values on the time axis, the averaging of the reception level values on the space axis can be dealt with similarly to the present invention.

[0033]

As described above, according to the present invention, only one buffer memory for storing the block average value is provided for each base station, and the measurement accuracy and the response to the reception level fluctuation are almost equivalent to those of the running averaging method. There is an excellent effect to obtain the property. Therefore, the buffer memory can be reduced by (m-1) as compared with the running averaging method in which the average number is m. When the number of base stations is N, it is possible to reduce the number by N × (m−1). Therefore, when N and m are large, the reduction effect is large.

The present invention is applicable not only to mobile communications, but also to all types of waveforms that need to be sampled at constant time intervals or spatial intervals using waveform buffers having temporal or spatial fluctuations with a minimum buffer memory to obtain a running average value. Applicable to the field.

[Brief description of the drawings]

FIG. 1 is a block diagram of a mobile communication reception level detection system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a reception level calculation method of the mobile communication reception level detection method of the present invention.

FIG. 3 is a flowchart showing processing of a mobile communication reception level detection method according to the present invention.

FIG. 4 is a diagram showing a detection result with respect to a rapid change of a reception level in the mobile communication reception level detection method of the present invention.

FIG. 5 is a diagram showing a comparison between the detection result of the mobile communication reception level detection method of the present invention and the detection results of the running averaging method and the buffer-saving memory averaging method.

FIG. 6 is a block diagram of a car telephone system.

FIG. 7 is a diagram showing a change in received electric field strength in a mobile communication system.

FIG. 8 is a view for explaining the averaging of the reception level by the traveling averaging method and the block averaging method of the conventional mobile communication reception level detection method.

FIG. 9 is a diagram showing detection results for a sudden change in the reception level by the running averaging method and the block averaging method of the conventional mobile communication reception level detection method.

FIG. 10 is a diagram showing a detection result of a buffer-saving memory type detection method of a conventional mobile communication reception level detection method.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 detection means 2 block averaging means 3 addition means 4 subtraction means 5 reception level averaging means 6 reception level value 7 block average value 8 averaged reception level 20 mobile communication control station 30 ₁ to 30 _I base station 40 mobile station 50 ₁ ５０50 _I wireless zone E ₁ ＥE _I Electric field strength f ₁ ｆf _I frequency

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/24-7/26 H04B 17/00 H04Q 7/00-7/38

Claims (1)

(57) [Claims] 1. A mobile communication reception level detection system comprising detection means for discretely detecting a reception level and outputting the reception level value, wherein a predetermined number of the reception level values from a detection start point are set in block units. Block averaging means for averaging to generate a block average value and outputting the block average value, and adding the reception level value each time the detection level is input from the start of detection, and the block average value of the block immediately before inputting the reception level value And a reception level calculating means for outputting the averaged reception level by dividing by a predetermined number.