JPH0946247A - Radio equipment - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To set an optimum carrier sense level according to a noise level to prevent malfunction of carrier sense in a noisy environment and to extend a communication distance in a noisy environment. . First, a noise level under a use environment is measured and stored in a work memory. Next, the CPU 12 selects the highest level of the noise level data stored in the work memory 14 and adds a predetermined noise margin to this to determine the carrier sense level. Then, using this carrier sense level, carrier sense for the received signal is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless device capable of automatically setting a carrier sense level in weak wireless communication.

[0002]

2. Description of the Related Art Some receivers in wireless communication have a carrier sense function for determining whether or not there is a radio wave in a frequency band used at a certain electric field strength. FIG. 5 is a block diagram showing the configuration of a wireless unit having such a carrier sense function. In FIG. 5, an antenna 100 that receives a radio signal from the transmitting side is a bandpass filter (BPF) 101 and an amplifier (AM).
P) 102 is connected to the first terminal of the mixer (MIX) 103, and the second terminal is connected to the oscillator 104. The third terminal of the mixer 103 is a low pass filter (L
The low-pass filter (LPF) 108 is connected to the comparator (COMP) 107 that outputs received data via the PF) 105 and the amplifier (AMP) 106.
It is connected to a comparator (COMP) 109 which outputs a carrier sense signal via.

[0003]

In the wireless communication, the electric field strength of the carrier output from the transmitting side is one of the factors that influence the communication distance of the wireless signal. That is, FIG.
As shown in (a), as the communication distance increases, the electric field strength of the carrier decreases and it becomes impossible to distinguish it from the noise signal. Therefore, in order to perform wireless communication normally, a carrier with an electric field strength higher than the noise signal is received. However, the maximum output is determined by the Radio Law in weak wireless communication.

Therefore, conventionally, as shown in FIG.
By setting the level above the noise level as the carrier sense level and regarding the received radio waves above this level, that is, when carrier sense is ON as received data, the noise signal is not mistakenly recognized as a carrier. I was doing.

However, since the above carrier sense level is fixed, when wireless communication is performed in an environment where the noise signal level exceeds the carrier sense level as shown in FIG. 6C. , FIG. 6 (c)
In the communication distance after L1, the noise signal is erroneously recognized as received data.

If the actual noise level is low when the carrier sense level is set high as shown in FIG. 6 (d), the communication distance can be reached even though the point L2 is actually available. When L exceeds L1, the carrier is turned off, so the reception of the received data is stopped.

As described above, when a fixed carrier sense level is used in the weak radio communication whose transmission output is determined by the Radio Law, the carrier sense operation malfunctions in a noisy environment, and There is a problem that the communication distance is shortened in an environment with weak noise.

An object of the present invention is to set an optimum carrier sense level according to a noise level to prevent malfunction of carrier sense in an environment where noise is strong and to extend a communication distance in an environment where noise is weak. is there.

[0009]

The means of the present invention are as follows. The noise level measuring means measures the noise level under the usage environment. The carrier sense level determining means determines a carrier sense level based on the noise level measured by the noise level measuring means. The carrier sense executing means executes carrier sense on the received signal using the carrier sense level determined by the carrier sense level determining means. The operation of the above-mentioned means of the present invention is as follows. First, the noise level measuring means measures the noise level under the usage environment. For example, a plurality of sampled values are obtained by sampling a noise signal input without a carrier a predetermined number of times in a fixed time. Next, the carrier sense level determining means determines the carrier sense level based on the noise level thus measured. For example, the carrier sense level is obtained by selecting the highest level from a plurality of sample values and adding a predetermined noise margin. Then, the carrier sense for the received signal is executed by using the carrier sense level thus determined.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
This will be described with reference to FIGS. FIG. 1 is an overall block diagram of a receiver to which the present invention is applied, including an antenna 1 for receiving a radio signal from a transmitting side, a radio unit 10 as a radio device, received data from the radio unit 10 and a carrier. CP that receives a sense signal and performs predetermined processing
It is composed of U20.

FIG. 2 is a block diagram showing the configuration of the above-mentioned wireless unit 10. In FIG. 2, a bandpass filter (BPF) 2 connected to an antenna 1 is connected to a first terminal of a mixer (MIX) 4 via an amplifier (AMP) 3, and its second terminal is connected to an oscillator 5. Has been done.
The third terminal of the mixer 4 is connected to the first terminal of the amplifier (AMP) 6, and the second terminal thereof is a low pass filter (LPF).
It is connected to an amplifier (AMP) 8 that outputs received data via 7. The third terminal of the amplifier 6 is connected to the first terminal of a comparator (COMP) 10 that outputs a carrier sense signal via a low-pass filter (LPF) 9, and the A / D converter 11 and the work memory 14 are connected. It is connected to the second terminal of the comparator 10 via the CPU 12 connected to and the D / A converter 13.

The operation of setting the carrier sense level of the above-mentioned wireless device will be described below with reference to the flowchart of FIG. First, when starting wireless communication, a noise signal input to the antenna 1 is sampled by the A / D converter 11 in a state where the transmitter is off, that is, in a state where there is no carrier, and the obtained sample value is loaded into the CPU 12. After that, it is stored in the work memory 14 (step S1). Such sampling is repeated a predetermined number of times for a fixed time (step S2), and the obtained plurality of sample values are sequentially stored in the work memory 14. Next, the maximum noise level is detected from the plurality of sample values stored in the work memory 14 (step S
3). Next, the result obtained by adding a predetermined noise margin to this maximum noise level is determined as the carrier sense level (step S4). Then, this carrier sense level is set in the D / A converter 13 and carrier sense is executed (step S5).

As described above, in this embodiment, the carrier sense level is changed according to the magnitude of the noise signal. That is, in a noisy environment, the conventional carrier sense level 2 is used instead of the fixed carrier sensor level 1 as shown in FIG. 4A, which is larger than the detected noise level by a noise margin. The malfunction at the communication distance after L1 as in the example is eliminated. Further, in an environment where noise is weak, as shown in FIG. 4B, the carrier sensor level 2 which is larger than the noise level by the noise margin is used instead of the fixed carrier sense level 1 as in the conventional case. Can be extended.

In the above-described embodiment, the process from the measurement of the noise level to the determination of the carrier sense level is digitally processed, but the carrier sense level may be determined by analog processing by using a peak detector or the like. it can.

[0015]

According to the present invention, the malfunction of carrier sense is eliminated in an environment where noise is strong, and the communication distance can be extended in an environment where noise is weak.

[Brief description of drawings]

FIG. 1 is an overall block diagram of a receiver to which the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a wireless device according to the present embodiment.

FIG. 3 is a flowchart for explaining a carrier sense level setting operation according to the present embodiment.

FIG. 4 is a diagram for explaining an effect of the present embodiment in comparison with a conventional example.

FIG. 5 is a diagram showing a configuration of a conventional wireless device.

FIG. 6 is a diagram for explaining a problem of a conventional wireless device.

[Explanation of symbols]

1 ... Antenna, 2 ... Bandpass filter (BPF), 3
... amplifier (AMP), 4 ... mixer (MIX), 5 ... oscillator, 6 ... amplifier (AMP), 7 ... low-pass filter (L)
PF), 8 ... Amplifier (AMP), 9 ... Low-pass filter (LPF), 10 ... Comparator (COMP), 11 ...
A / D converter, 12 ... CPU, 13 ... D / A converter, 14 ... Work memory.

Claims (1)

[Claims] 1. A noise level measuring means for measuring a noise level under a use environment, a carrier sense level determining means for determining a carrier sense level based on the noise level measured by the noise level measuring means, A radio apparatus comprising: a carrier sense executing unit that executes a carrier sense for a received signal using the carrier sense level determined by the carrier sense level determining unit.