JPS6276831A - Cordless telephone system - Google Patents

Abstract

PURPOSE:To transmit/receive information between a fixed device and a cordless telephone set without being subject to interference even in an area where service areas are overlapped by sending an idle line signal to an idle channel different from the detected channel, and transmitting/receiving the information with the cordless telephone set receiving the idle line signal. CONSTITUTION:When a CE sends an idle line signal, the strength of an electric field received from an antenna 2-3 via a receiver 2-8 is scanned by a controller 2-4 over all channels and whether or not a channel is idle based on the electric field strength. In such a case, when the level of the electric field is a prescribed value or over, the channel is busy and the channel scan is applied again. On the other hand, when the reception electric field is smaller than a prescribed value, the channel is an idle channel and in such a case, whether or not other CE adjacent to the service area sends an idle line signal is decided. Then the idle line signal is received by a receiver 2-8. Thus, the system where the channel utilizing factor is improved and the interval between the fixed devices is small is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cordless telephone system, and more particularly to a cordless telephone system suitable for avoiding interference phenomena due to the same channel radio waves from a plurality of fixed devices.

[Conventional technology]

Conventionally, in the cordless telephone system, as shown in FIG. -1 and T e ]41-3. That is,
In the service area 41-2 of CF4I1, Te141-
Only 3 was said to be able to communicate with CF4I1. Each CE
41-1, 42-] are arranged independently, and this system is designed so that the distance between each CE is between the CE and its corresponding Tel.
This system was designed on the premise that the distance is sufficiently larger than the distance between the Therefore, in this system, when the number of users increases and CEs are placed close to each other as shown in FIG. 4(b), radio wave interference occurs.

For example, Te143-3 is CE43-1 and CE44-1
If each CE is located in an overlapping area 46 of the service area, the Te
143-3 will receive interference from this radio wave.

Also, as shown in Figure 3, in recent years CE and Tel have become one
A cordless telephone system that does not support on a one-to-one basis, ie, a system that allows telephone calls in any CE service area, has been proposed. However, in this system, for example, Te139-1 is CF3I-1, 32-1, 33-1
If you make a call at a point where the service areas of CE311 and 34-1 overlap, even if the antenna signals broadcast by CE311 and 32-1 are on the same frequency, the antenna signals broadcast by CE33-1 and CE34-1 will overlap. If the signals are different signals, Te139
-1 can capture either the idle signal broadcast by CE33-1 or CE34-1. However, if both the CEs 33-1 and 34-1 are in call service, the idle line signals of the CF3I-1 and 32-1 interfere with each other, so the Te 139-1 cannot capture the idle line signals. In this way, if at least two CEs are broadcasting antenna signals of the same frequency, Te
139-1 will not be able to capture the idle line signal. As a result, even in cordless telephone systems that do not have one-to-one correspondence, radio wave interference may occur on the same channel in areas where service areas overlap.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional cordless telephone system, which supports CE and Tel on a one-to-one basis, co-channel interference cannot be avoided when the number of users increases and the service areas of each CE overlap. Furthermore, even in cordless telephone systems where CE and Tel do not correspond one-to-one, it is difficult to avoid radio wave interference on the same channel in areas where service areas overlap.

An object of the present invention is to provide a cordless telephone system that allows information to be exchanged between a fixed device and a cordless telephone without interference even in areas where service areas overlap.

[Means for solving problems]

The present invention provides a cordless telephone system in which information is exchanged between a plurality of fixed devices whose service areas overlap with each other and a plurality of cordless telephones in each service area, in which each fixed device receives radio waves in its own service area. detecting a group of empty channels from among them, and detecting a channel of an empty wire signal sent by another fixed device from among the empty channels;
The system is characterized in that it sends a blank line signal to an empty channel different from the detected channel, and exchanges information with the cordless telephone that receives the idle line signal.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows the configuration of a preferred embodiment of the invention. In FIG. 2, each CE includes an antenna 2-3, a duplexer 2-6, a BPF 2-9, 112, a switch 110, 1
11, transmitting device 2-2, receiving device 2-8, control device 2-
4, a synthesizer 2-5, and a connecting device 2-7, and a telephone line 2-1 is connected to the connecting device 2-7.

Switches 2-1n and 2-1.1 normally have terminals A and D connected to BPF2-9. 1-1 and 1-2, and is switched to terminals B and C when detecting a vacant line signal in an adjacent service area. In addition, BPF 2-9 is configured with a band in which radio waves of the received Tel transmission frequency do not enter the transmitter 2-2, and BPF 2-12 is configured with a band in which radio waves of the transmission frequency band used by other CEs are not received. It is made up of.

The present embodiment has the above-mentioned configuration, and its operation will now be explained based on the flowchart of FIG. 1.

Antenna 2-3 when CE transmits a blank signal until
The control device 2-4 scans the intensity of the electric field received from the receiver device 2-8 over all channels (Sl
). Based on this electric field strength, it is determined whether the channel is empty or not (S2).

If it is determined in this step that the magnitude of the electric field is greater than a certain value, that channel is in use and the channel scan is performed again.

On the other hand, when the received electric field is smaller than a certain value, the channel is an empty channel that is not used within the service area of the CE. In this case, it is determined whether or not the CEs 32-1, 33-1, etc. are sending out idle signal signals to other CEs adjacent to the service area, for example, CE 31-1 (S3). When performing this detection, the control device 2-4 switches the frequency band to be checked to the idle frequency of the same channel, and connects the switch 2-10 to the terminal B and the switch 2-11 to the terminal C, respectively. Then, the receiving device 2-
Received by 8. If the magnitude of this electric field is greater than a certain value, it means that the channel is transmitting a blank signal in an adjacent CE in the service area. If an idle signal is sent on such a channel, interference will occur in areas where the service areas overlap, and Te
Since it becomes impossible to receive the idle line signal on the l side, the channel scan process is performed again without transmitting the idle line signal.

On the other hand, if the received electric field is smaller than a certain value, it is assumed that the channel is currently an empty channel and that no adjacent CE in the service area is transmitting an empty signal, that is, it is a channel where no interference phenomenon can occur. It will be done. In this case, switch 2-10 is connected to terminal A, and switch 2-11 is connected to terminal A.
is connected to the terminal, and a blank wire signal is sent out (S4).

Next, it is determined whether or not a calling signal from Tel is received (S5), and when a calling signal is received, the telephone line 2
~1 is connected (S6). Then, to start a conversation with the received Tel (S7), it is determined whether or not the other party Th is on-hook (S8). When the other party's Tel is on-hook, a channel scan is performed, and when the other party's Tel is not on-hook, the call is continued, and the processing in this routine ends.

On the other hand, when making a call from the Tel side, (b) in Figure 1
When a call request is made as shown in (SIO),
Scan across all channels (Sll). and C
It is determined whether or not a blank line signal from E has been received (S
i2) When receiving a blank line signal from the other party's CE, it transmits a calling signal (S13). Then, a conversation is started with the other party CE (514), and this conversation is continued until on-hook (S15).

On the other hand, when the antenna signal is not received, that is, when the antenna signal is not output from any CE, or when the antenna signal cannot be received due to an interference phenomenon, a busy tone is output (516), and this process is performed. continues until it is on-hook (517). And after each process, please reset 3.
18), the process of step SIO is performed again, and the process of this routine is completed.

As described above, in this embodiment, since the CE side performs the operation of transmitting the idle line signal while avoiding the channel on which other CEs adjacent to the service area are transmitting the idle line signal, It can avoid signal interference phenomenon. Note that interference between antenna signals can occur only when adjacent CEs in the service area start transmitting antenna signals on the same channel at the same time, but this probability is extremely low.
can capture a channel free of interference phenomena.

Furthermore, in this embodiment, since all interference avoidance operations are performed on the CE side, the Tel side does not need to have any functions related to this operation.

Moreover, this allows the Tel to be made smaller and lighter, and along with this, it is possible to reduce costs.

Furthermore, a cordless telephone system that provides multiple Tel services for a CEI unit can be constructed at low cost, and the service itself can become more widespread.

〔Effect of the invention〕

As explained below, according to the present invention, each fixed device detects a group of empty channels from the radio waves in its own service area, and also detects the empty channel signals sent by other fixed devices from among these empty channels. The system detects the channel, sends out an idle line signal to an empty channel different from the detected channel, and exchanges information with the cordless telephone that receives the idle line signal, so the cordless telephone is free from interference. This has the advantage of being able to acquire new channels, realizing a system with improved channel utilization and small fixed device spacing, and increasing the capacity of system subscribers.

[Brief explanation of drawings]

Figure 1 is a flowchart explaining the operation of the device to which the present invention is applied, Figure 2 is a configuration diagram of the fixing device to which the present invention is applied, and Figure 3 is when the service areas of multiple CEs overlap. Figure 4 is a diagram explaining the cordless telephone system of C.
It is a diagram for explaining a cordless telephone system in which E and 'I'el correspond on a one-to-one basis. 31-1.32. -1.33-1.34-1.35-1
．． 41-1゜42-143-1.44-1.45-1・
...... Fixing device 39-1. 39-
2. 41-3. 42-3. 43-3. 411-
3゜45-3 ・・・・・・・・・・・・・・・・・・
・・・・・・ Cordless telephone 2-2 ・・・・・・
・・・・・・・・・・・・・・・・・・・・・ Transmitter 2-4 ・・・・・・・・・・・・・・・・・・・・・
...... Control device 2-8 ...... River... For one mountain... '1 Shin' AM agent Patent attorney Yoshiyuki Iwasa (a) Figure 1 (b ) Figure 1

Claims (1)

[Claims] (1) In a cordless telephone system in which information is exchanged between multiple fixed devices whose service areas overlap with each other and multiple cordless telephones in each service area, each fixed device transmits information within the radio waves of its own service area. At the same time, it detects a group of empty channels from the empty channel group, detects a channel of an empty line signal sent by another fixed device from among these empty channels, sends an empty line signal to an empty channel different from the detected channel, and detects the empty line signal from the empty channel group. A cordless telephone system characterized by exchanging information with a cordless telephone that receives the information.