JPS6132857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interference wave monitoring system for wireless communication having a common control channel.

In wireless communication having a common control channel, if interference waves enter the radio band in which a control response signal is received, the response signal is suppressed by the interference waves and cannot be received. Especially since it is commonly used, there is a high possibility that it will cause fatal interference throughout the system.

Conventionally, to detect this interference, measurements were taken with an electric field strength meter during system installation or during quiet periods at night. However, according to this method, it is difficult to detect interference waves that occur in a relatively short period of time. In addition, in order to continue measuring regularly during operation, in order to discover new interference waves generated after installation,
In some cases, system operation had to be temporarily stopped during the measurement period. Furthermore, when a large number of receivers are used to service a wide area, it is impossible to constantly monitor and monitor each receiver.

The present invention focuses on the fact that all wireless slave stations included in a system are controlled by downlink control signals sent from a wireless base station to a common control channel. We have developed an interference wave monitoring method that allows continuous and automatic monitoring without interrupting system operation by ensuring a period of time during which the uplink channel is not used by the system, and determining the presence or absence of interference waves during this time. This is what we provide.

The present invention provides a method for transmitting signals to the base station on the basis of a promise that signals having a length longer than a known fixed time will not be sent upstream on a control channel from a wireless slave station controlled by a control signal broadcast from a wireless base station. Automatic system control is achieved by securing unused time for the uplink control channel in the system consisting of the station and the slave stations, measuring the electric field strength at the base station during this time, and determining the presence or absence of interference waves. This method allows constant monitoring without interrupting operations.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the case of two base stations, and 1 is a control signal downlink input terminal, into which the downlink control signal shown in FIG. 2 is input, and is broadcast as radio waves by a control channel downlink transmitter (TX) 5. In Figure 1,
DUP is a duplexer and ANT is an antenna. An uplink response signal from a mobile device (not shown) is received by a control channel uplink receiver (RX) 6, and a TONE with a frequency proportional to the electric field value is sent out from a variable frequency oscillator (VFO) 7 and sent to a gate 4. The number of waves is counted by the counter 8 via. The gate 4 is opened only in the section γ in FIG. The timer 9 keeps the time γ, and is reset and started after a known time (α+β) after sending _P1 , as shown in FIG. In Figure 2, An(n=1, 2, 3,
) is a control signal other than a call to the mobile device (i.e., a control signal that does not specifically request a response from the mobile device), Pn
(n = 1, 2, 3, ...) is a control signal that requests a response from the mobile device, α is the processing time in the mobile device and the delay time length due to lines, etc., RPn (n = 1, 2,
3,...) is a response to Pn from the mobile device and its time is β. γ is the time from when the next call is received until the response from the mobile device (i.e., the length of time from the end of receiving RP ₁ to the reception of RP ₂ ), and γ is the time length of A ₂ . Can be controlled.

If the mobile terminal is guaranteed to respond only to Pn, after broadcasting _P1 , gate 4 is opened after a known time α+β, and γ is detected at counter 8.
Receive the electric field information TONE (sent by vfo7) for the section,
By counting the number of waves during that time, the electric field strength during that time can be measured. When some kind of radio wave is received in the γ interval, the output frequency of vfo7 increases,
The count amount of the counter 8 increases, and it can be determined that there is an interference wave. As described above, it is possible to monitor interference waves even during operation by providing γ.

As explained above, the present invention synchronizes the slave stations with the control signals broadcast from the base station.
Since the uplink control channel is set for non-use time and the presence or absence of jamming waves is determined within this time, jamming waves can be automatically monitored at all times without stopping the entire system even during operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a partial block diagram of an embodiment of the present invention, and FIG. 2 shows a downlink control signal broadcast by the system shown in FIG. FIG. 3 is a timing diagram showing timing. In FIG. 1, 1 is a control signal downstream input terminal;
2 is the reset terminal of timer 9, and 3 is the terminal in the interval γ.
Output wave number count output of vfo7, 4 is the gate controlled by timer 9, 5 is the control channel downlink transmitter (TX), 6 is the control channel uplink receiver (RX), 7 is proportional to the electric field value received by RX6 A variable frequency oscillator (VFO) outputs a frequency TONE, and 8 is a counter that counts the number of output waves of the oscillator 7. In Fig. 2, A ₁ , ..., An are control signal sequences that do not particularly require a response from the mobile device, P ₁ , ..., Pn are control signal sequences that require a response from the mobile device, and RP ₁ , ..., RPn are control signal sequences that do not require a response from the mobile device.
P ₁ ,..., response signal sequence for Pn, α is the processing time in the mobile device and delay time length due to lines, etc. β is the response signal sequence for Pn from the mobile device
The reception time length of RPn, γ, is the time length from the end of reception of RPn until the reception of RP _o+1 .

Claims (1)

[Claims] 1 A wireless base station having a measuring means for measuring received field strength, and a wireless slave station that transmits a response signal with a known transmission time length in synchronization with a control signal broadcast from the base station, The station is characterized in that the station determines the presence or absence of interference waves by securing a time during which the slave station does not transmit the response signal and measuring the received electric field strength during the time using the measuring means. Interference monitoring method.