JPH02164143A - Method for measuring quantity of interference - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an interference amount measurement method suitable for a wireless communication system that performs intermittent transmission such as The present invention relates to a method for measuring the amount of interference, which can measure the amount of interference in a phase modulation method, an amplitude modulation method, etc., in which it is difficult to measure the amount of interference using a measurement method, in the same way as in a frequency modulation method.

[Prior art and problems to be solved by the invention] Color interference occurs when a desired wave and an interference wave are simultaneously received for angle modulation systems (frequency modulation systems, broadband phase modulation systems) in which the amplitude of the modulated wave is constant. A measurement method has been developed in which a beat occurring in a line detection output is measured and the amount of co-frequency interference is determined from the average received power and the average power of the beat.

However, in modulation methods in which the amplitude of the modulated wave changes (narrowband phase modulation method, amplitude modulation method, etc.), it is difficult to detect beats, and conventional beat detection measurement methods cannot be applied.

An object of the present invention is to provide an interference amount measuring method that makes it possible to measure interference 1 regardless of the modulation method in an intermittent transmission type communication system.

[Means to solve the problem]

The object of the invention is achieved by the method defined in the claims.

That is, in the present invention, when there is a signal to be transmitted, the transmission output is turned on and normal transmission is performed, and when there is no end-of-transmission signal, the transmission output is turned off or the transmission output level is set to low level, and the transmission is performed. Intermittent transmission type communication method that temporarily suspends or lowers the level of
In the measurement method, on the receiving side, based on the reception level or reception information, the reception level is determined to be the reception level during the period when the signal is determined to be transmitted at a high level, and the reception level during the period when the signal is not transmitted or is transmitted at a low level. Measure the reception level during the determined period, and use the measured reception level, the average value of the time with a signal, and the average value of the time without a signal,
This method estimates the average received level of the desired wave and the average received level of the interference wave, and uses the ratio of the estimated value of the received level of the desired wave to the estimated value of the received level of the interference wave as the amount of interference.

Hereinafter, the effects of the present invention will be explained based on Examples.

〔Example〕

FIG. 1 is a diagram schematically showing how the reception level changes in an intermittent transmission type communication system when interference is present.

The average value of the reception level of the desired wave is D1 The average value of the reception level of the interference wave is 01 The average value of the time when the signal is present T On 1
Let Taff be the average value of the time without a signal. T of interference wave
on, Toff are desired wave T On 5Toff
Assume that it is the same as

The transmission time rate P is defined by the following equation.

The average value of the reception level (high level) of Mm with signal presence 9. n is L On = D + P U ・・・・・・・・・
... (2), and the reception level during the period of no signal (
The average value Loff of low level) is Loff=PU ・・・・・・・・・・・・
(3).

Therefore, the interference 11 (ratio of the average reception level D of the desired wave to the average reception level U of the interference wave) DUR is determined by the following equation.

FIG. 2 is a block diagram of one embodiment of the present invention.

In this embodiment, immediately after turning on the transmission output, a preamble signal is used to notify the start of transmission, and then normal transmission is started.
This is also an example of an intermittent transmission method in which the transmission output is turned off after the transmission output is forewarned by a postamble signal immediately before the transmission output is turned off.

In Figure 2, the preamble/postamble signal detection circuit (indicated by "pre/post signal detection circuit" in the diagram)
When a preamble signal or a postamble signal is detected from the received data, the circuit 1 outputs a detection signal to the signal presence/absence determination circuit 3.

The AD conversion circuit 2 converts the received level into a digital signal and outputs it to the signal presence/absence determination circuit 3 and the interference amount calculation circuit 4.

The signal presence/absence determination circuit 3 determines that a signal is present when a preamble signal is detected or when the reception level is higher than a preset first threshold, and when a postamble signal is detected or when the reception level is higher than a preset first threshold. When it is lower than the set second threshold value, it is determined that there is no signal, and a determination signal is output to the interference amount calculation circuit 4.

The interference amount calculation circuit 4 determines whether there is a signal wIl based on the signal presence/absence determination signal and the reception level signal. 11 average received ν Bell L O
n % Average reception level L during no signal period. a and the transmission time rate P, and calculate and output the interference fiDUR using equation (4).

In this embodiment, the transmitter may reduce the output level instead of turning off the transmission output (the level control of the transmission output in this method is also referred to as "high-low control").

FIG. 3 is a diagram showing how the reception level changes when the transmission output level is controlled high/low. The average value of the reception level of the desired wave when the transmission output level of the desired wave is high level, and the average value U of the reception level of the interference wave when the transmission output level of the interference wave is high level, and the transmission output level is high level. The ratio of the transmission output level when the signal is low to the transmission output level when the signal is low is assumed to be T, and it is assumed that T of the desired wave and T of the interference wave are equal.

At this time, the average value of the reception level during the period when the signal is present L O
n is Lon =D+r(1-P)U+PU ・-・-・(5
), and the average value of the reception level during the period without signal Lor
i is Loa = TD+T(1-P)U+PU.

Therefore, the interference fiDUR is... (7) In this case, in the interference figure output circuit 4 of Fig. 2, equation (7) is used instead of equation (4). The amount of interference can be calculated using

If T is sufficiently small, equation (7) becomes off This is consistent with equation (4).

〔Effect of the invention〕

As described above, the interference amount measuring method of the present invention is suitable for a wireless communication system that performs intermittent transmission, and enables interference amount measurement regardless of the modulation method.

[Brief explanation of the drawing]

FIG. 11 is a diagram showing how the reception level changes in an intermittent transmission type communication system when interference exists, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 11 is a diagram showing how the reception level changes when the signal is low. FIG. 1...Preamble/postamble signal detection circuit, 2...AD conversion circuit, 3
...Signal presence/absence determination circuit, 4...
・・Interference amount calculation circuit No. J1 Signal interference There is interference. Diagram 2

Claims (1)

[Claims] When there is a signal to be transmitted, the transmission output is turned on and normal transmission is performed, and when there is no signal to be transmitted, the transmission output is turned off or the transmission output level is set to a low level, and transmission is performed. In an interference measurement method used for intermittent transmission communication systems that temporarily suspend or lower the level of the signal, the receiving side determines the reception level during the period when the signal is determined to be being transmitted at a high level from the reception level or reception information, and Measure the reception level during the period when it is determined that the signal is not being transmitted or is being transmitted at a low level, and calculate the measured reception level, the average value of the time with a signal, and the average value of the time with no signal. is used to estimate the average received level of the desired wave and the average received level of the interference wave, and the ratio of the estimated value of the received level of the desired wave to the estimated value of the received level of the interference wave is defined as the amount of interference. How to measure the amount of interference.