JPS59123325A - Automatic selecting and controlling system of decentralized base station - Google Patents

Abstract

PURPOSE:To attain correspondence with good sensitivity even if talking is executed immediately after pressing by comparing received electric field signals mutually when the level of the received electric field signal reaches a felt level or an unfelt level and discriminating a selected base station so as to change over a line. CONSTITUTION:A star line network tying the base stations 1 located decentralizingly and a supervisory station 3 are provided, the strength of electric field of a radio wave incoming to each base station with a level from a mobile station is quantized, the quantized received electric field signal is modulated by the frequency shift modulation for the felt level and the interruption of signal for the unfelt level, the result is transmitted to the supervisory station and inputted to a computer 11. The state of the electric field signal received from each base station is compared immediately by the control of the computer 11 when the level of the received electric field signal from each base station 1 reaches the felt level and is decreased to the unfelt level so as to select the base station.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributed base station land mobile radio system using a simplex system (alternate transmission and reception), and in particular to arranging base stations and monitoring stations to form a constellation network. This invention relates to an automatic distributed base station selection control system that makes it possible to simultaneously achieve rapid communication, high reliability, and low cost when applied to mobile radio services that have a two-dimensional spread.

Conventionally, in a simplex system distributed base station land mobile radio system, as shown in FIG. 1, each base station is arranged in such a way that it is cascaded with a line, and a monitoring station 3 → mobile station 2 . Or, prioritize depending on the direction of communication, such as mobile station 2 → monitoring station 3.
The received electric field signal is given in advance in order from the base station located at one end of the network, and the received electric field signal is transmitted from the base station located at one end of the network to the base station located at the other end. The system was such that the line switching device 10 was turned on and off by comparing the received electric field signals of the base station, the lower base station, and the own station.

In this type of system, since calls are sent and received alternately, the mobile station 2
No matter which base station 1 in the network is located within the coverage area, the base station 1 receives the received electric field signal every time it communicates.
Since the base station selection operation is not completed during the time from detection to all base stations in the line network and input to the determination device 16 of each base station, the selection delay time becomes long and However, this method has the disadvantage that it is necessary to wait for the selection operation to be completed before transmitting a message.

Furthermore, if the approach line 4 between base stations in the middle of the line network is disconnected, or if a failure occurs where the electric field signal transmitter 14 is stuck in the electric field signal transmission state, normal communication will not be possible. It has the disadvantage that it is completely impossible.

In addition, since the line network has base stations arranged in a linear manner, if it is necessary to arrange base stations in a planar manner, the number of connections and line distance will increase, which has the disadvantage of increasing costs. There is.

The car telephone system is a system in which the line network is configured in a star shape and base stations are selected centrally at a central monitoring station, but this system is a duplex system (simultaneous sending and receiving calls), is constantly receiving radio waves from mobile stations, and
This transmission method, which transmits the received electric field signal to the monitoring station, is a digital method and is either a cyclic method for a fixed period of time or a polling method based on a request from the monitoring station.
The monitoring station compares the electric field signals received from each base station at regular intervals to determine the base station.

Therefore, this method requires a long time to transmit the received electric field signal and determine the selected base station when the radio waves are started and stopped for each communication as in the simplex method (alternate transmission and reception). It has the disadvantage that communication cannot be performed normally. Furthermore, each base station requires a transmission control function for digitally transmitting the received electric field signal to the monitoring station by a cyclic method or a polling method, which has the disadvantage of increasing costs.

The present invention quantizes the electric field strength of radio waves felt by a mobile station into a base station into several levels, and when the quantized received electric field signal is at a sensitive level, frequency shift modulation is performed depending on the level, and an insensitive level is applied. The signal is transmitted to the monitoring station in such a way that the signal is cut off when When the level of the received electric field signal reaches a sensitive level or drops to an insensitive level, the received electric field signals are immediately compared with each other, the selected base station is determined, and the line is switched. In this way, the present invention provides a distributed base station automatic selection control system that solves the above-mentioned drawbacks.

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 2, which shows a system diagram of the automatic fractional base station selection control system according to the present invention, in one embodiment of the present invention, a plurality of distributed base stations 1 and a monitoring station 3 are connected to an approach line 4.
are connected to form a star-shaped network. Further, radio waves emitted from the mobile station 2 pass through the antenna 5 of the base station 1 and are received by the simplex radio transmitter/receiver 6 . The low frequency signal detected by the simplex wireless transmitter/receiver 6 passes through the modulator 8, the approach line 4, and the demodulator 9 of the monitoring station 3.
and is input to the line switching device 1o.

A low frequency signal from the selected base station is selected by the line switching device 10 under the control of the computer 11 and sent to the transmitting/receiving device 1.
2 and amplified as audio. Conversely, the voice input to the transmitting/receiving device 12 is input as a low frequency signal to the line switching device 1o, passes through the Q demodulator 9 through the p approach circuit a4 under the control of the computer 11, and is sent to the selected base station 1. transmitted to. At the base station 1, this low frequency signal is input to the simplex radio transmitting/receiving device 6 via the modulating device 8.
It passes through the antenna 5 and is emitted as a radio wave. The mobile station 2 is configured so that this radio wave reaches the mobile station 2 and communication is performed.

On the other hand, the base station 1 input to the simplex wireless transmitter/receiver 6
The carrier component of the high frequency signal of the received radio wave is extracted by the device and input to the received electric field quantization device 7. The input carrier wave signal is quantized by K in the received electric field quantizer 7, and when the power of the signal is compared with the reference electric power,
It is input to the modulation device 8 as a received electric field signal. This received electric field signal is modulated by the modulation device 8 so that the sensitive level is frequency shift keying and the insensitive level is signal disconnection, and is sent to the approach line 4. The received electric field signal sent to the approach line 4 is demodulated by the demodulator 9 of the base station 3 and input into the computer 11 in various forms.

Next, the operation of one embodiment of the present invention will be explained. As the mobile station 2 moves, the power of the carrier component of the radio frequency signal input from the antenna 5 of the base station 1 to the simplex radio transmitter/receiver 6 changes as shown in the received electric field fluctuation time chart 18 of FIG. It changes from time to time. The received electric field quantizer converts the power value of this carrier wave component into an insensitive level and a sensitive level 1. Quantize to sensitivity level 2. This level is set according to the following relationship. Noise level ← Insensible level < Sensitive level 1 Sensitive level 2 → Sensitivity increased, quantization is performed after the input exceeds a certain reference value until that reference value rises and falls to a low sensitivity reference value. ,
It has a hysteresis characteristic that makes the reference value the quantization level. The quantized received electric field signal is modulated by the modulation device 8 in such a manner that the sensitive level is frequency shift modulated and the insensitive level is signal disconnection, as shown in the electric field signal time chart 19 of the approach line in Fig. 3. It will be like that.

In the figure, °cs f is the carrier frequency of the signal, and Δf is the frequency deviation. This received electric field signal is frequency division multiplexed with the audio component and sent to the approach line 4 as shown in FIG. This received electric field signal is demodulated by demodulator 9 of the monitoring station and input to computer 11 .

As shown in FIG. 4, the combination 11 constantly monitors the presence or absence of a change in the received electric field signal from each base station from an insensitive level to a sensitive level or vice versa.

Assuming now that no base station 1 is selected, its state is in the "non-selecting" state. In this state, if a base station that changes from an insensitive level to a sensitive level appears (timing to in Figure 3), the level of the received electric field signal from each base station will be compared. Compare levels.

Based on this comparison result, “Select the highest level base 1”
Through processing, only one base station with the highest received electric field level is selected, and if there are two or more base stations with the same level, it is selected according to a predetermined priority order, and the line switching device 10 is controlled to select the base station with the highest received electric field level. Base station 1 selects approach line 4. The state after selection becomes the "selection hold" state ■.

Thereafter, even if the received electric field signal from a non-selected base station changes (timings t2, t4, and t5 in FIG. 3), the selection of the base station is not changed because the same "hold selection" state (2) is maintained.

Even if the received electric field signal from the currently selected base station changes within the perceivable level (timing tl in FIG. 3).

t3) The base station selection is not changed since the "selection hold" state (■) is maintained.

When the received electric field signal from the selected base station 1 changes from a sensitive level to an insensitive level (tie in FIG. 3).

Mink t6), the state becomes "selection switching standby" state ■. In this state, the base station waits for the received electric field signal from another base station to change from an insensitive level to a sensitive level, and the selection remains unchanged. In this state, when a base station whose received electric field signal changes from an insensitive level to a sensitive level appears (timing t8 in Figure 3), [Compare the levels of each base station - 1 process] Compare the levels of received electric field signals. If there is a base station whose received electric field signal remains at a perceivable level due to the "comparison permission" regulation item (timing t7 to t8 in Figure 3, base station C), the comparison will not be performed for that base station. It works to remove it from the target. Based on this comparison result, the base station with the highest level of the received electric field signal is selected by the "select base with the highest level" process 23. (Timing t8 in FIG. 3) As a result, even if a faulty base station appears where the received electric field signal is fixed at a perceptible level, communication can be carried out without any problem.

5. In addition, in the above process, it is possible to prevent base stations that are unavailable due to human judgment, maintenance, failure, etc. from being selected by the "selection permission" restriction item 22.
It is possible to disconnect the faulty base station and perform degenerate operation.

As described above, the base station selection control in the computer 11 is performed immediately when the received electric field signal changes from an insensitive level to a sensitive level (or vice versa), and the time required for this control is on the order of milliseconds. Since it is sufficiently fast, it is possible to perform communication quickly and with high sensitivity.

Furthermore, due to the characteristics of the modulator 8 and demodulator 9, the standing phenomenon that occurs as the mobile station 2 moves is caused by the delay and delay when changing from a signal present to no signal, and from no signal to a signal present. It is possible to avoid fluctuations in base station selection due to absorption by hysteresis characteristics.

As explained above, the present invention uses the simplex system (alternate transmission and reception).
In the land mobile radio system of The received electric field signal is modulated using frequency shift keying for sensitive levels and signal cutoff for insensitive levels, and is transmitted to a monitoring station and input to a computer. Under computer control, signals from each base station are modulated. When the level of the received electric field signal reaches a sensitive level or drops to an insensitive level, the state of the received electric field signal from each base station is immediately compared and the base station is selected. Therefore, even if you send a call immediately after pressing, you can communicate with good sensitivity. Even if one base station has a problem, communication will not be impossible due to this.
Because the line network is star-shaped, the line distance is shorter than that of conventional systems, and at each base station, only the quantization and modulation functions of the carrier wave power of the received radio waves are added to the wireless equipment. This has advantages such as low cost and the like.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an example of a conventional system, Fig. 2 is a system diagram showing an embodiment of the present invention, and Figs. 3, 4, and 5 are timing diagrams for explaining the present invention in detail. They are a chart, a state transition diagram, and a frequency band division diagram of a line. In the figure, 1 is a base station, 2 is a mobile station, 3 is a monitoring station, 4 is an approach line, 5 is an antenna, 6 is a simplex radio transmitter/receiver, 7 is a received electric field quantizer, 8 is a modulator, 9 is a demodulator, 10 is a line switching device, 11 is a computer, 12 is a transmitting/receiving device, 13 is an electric field signal extraction device, 1
4 is an electric field signal sending device, 15 is a telephone line branching device, 16
17 is a determination device, 17 is a line termination device, 18 is a received electric field fluctuation time chart, 19 is a received electric field signal time chart of the approach line, 20 is a base station selection time chart, 2
1 is an internal state, 22 is a regulation item, and 23 is a processing warning. ,〆 , Yu17. i Agent Patent Attorney Uchihara Hi ＼ 411. 2, -''S, 3 Figure 1 sun) 4 C selection and 2 (11 each A to L of d?. Atsushi 5 times)

Claims (1)

[Claims] In a control system for a distributed base station, in which distributed base stations and a central monitoring station are connected by a star IO network, and communication between a mobile station and the base station is performed by a simplex system (alternative transmission and reception). , each base station quantizes the electric field strength of the radio waves received from the mobile station, and modulates the received electric field signal by frequency shift keying for the sensitive level and by signal interruption for the insensitive level. Immediately when the received electric field signal level from each base station reaches a predetermined sensitive level or drops to a predetermined insensitive level, 2, characterized in that the received electric field signal levels from each of the base stations are compared and a base station with the highest received electric field strength or a base station according to a predetermined priority is selected.
Distributed base station automatic selection control system.