JP2593777B2 - Cellular system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular system used for various wireless LANs and mobile communication systems.

[0002]

2. Description of the Related Art In a wireless LAN (Local Area Network), a signal radio wave is transmitted from each of a plurality of fixed stations using different carrier frequencies, and a plurality of cells defined by the reach of each radio wave are formed adjacently. Is done. FIG. 5 shows the configuration of such a wireless LAN when the number of cells is six.
For example, six cells C _{1 to} C ₆ defined by the reach of radio waves transmitted from the fixed stations F _{1 to} F ₆ to which different carrier frequencies f _{1 to} f ₆ are allocated are adjacent to each other. It is formed. The fixed station in each cell is provided with a directional antenna for transmitting a radio wave including a signal in each sector divided into sectors in each direction in the own cell around the fixed station. In the example of FIG. 5, as representatively shown by the cell C _1, a cell is divided into sectors S ₁ to S ₆ of the six sector having an angle of 60 ° about a fixed station C _1. A signal transmitted to each sector is provided with a sector identification function. Handset M ₁ that is installed in each cell, M _2, M ₃ ···
Transmits and receives signals to and from the fixed station of the cell to which the terminal belongs. Each fixed station C ₁ -C ₆ is connected to a host device by wire transmission path.

[0003] When the slave unit moves to a different cell due to the rearrangement of the slave unit, an operator who rearranges the slave unit assigns the radio frequency used by the slave unit to the cell before movement. A frequency switching operation of switching from the assigned cell to the cell assigned to the new cell at the movement destination is performed.

[0004]

SUMMARY OF THE INVENTION The present inventor has proposed to apply the above-mentioned conventional wireless LAN to a product guidance service in a supermarket or the like. That is, a plurality of cells are formed in a store where various products are displayed, each cell is divided into a plurality of sectors, and a child device is mounted on a cart that moves across each sector in each cell, The product guidance information on what products are displayed near this slave unit is transmitted from each fixed station as a different signal for each sector in its own cell, and the product guidance information is displayed on each cart. This is to be displayed on the device. A similar wireless LAN can also be applied to the positioning of a robot car that automatically travels in a warehouse or a factory.

[0005] In order to realize the above-mentioned product guidance service and the like, it is necessary to solve the problem of how to make a cart or the like automatically recognize the position of its own station and perform frequency switching. That is, unlike the conventional wireless LAN, it is difficult to make a customer who uses a cart or the like perform a frequency switching operation. There is also a problem of how to increase the positioning accuracy conventionally determined by the size of each sector.

[0006]

According to the cellular system of the present invention which solves the above-mentioned problems, each mobile station receives radio waves transmitted from each fixed station and includes the level of these radio waves or the level of these radio waves. Inter-cell positioning means for detecting the cell to which the terminal belongs, based on the reliability of the received signal and the frequency of the corresponding received radio wave, and receiving radio waves transmitted from each fixed station in the positioned cell into each sector and receiving each radio wave. Inter-sector positioning means for detecting the sector to which the own device belongs in the cell based on the level of the signal and the sector identification function added to the signal included therein, and the position of the own device in the detected sector In-sector positioning means for detecting whether it is closer to or farther from the fixed station based on the level of a radio wave received from the fixed station. According to a preferred embodiment of the present invention, each fixed station is provided with a means for transmitting a signal specific to each position, and each mobile station receives a signal transmitted by the fixed station based on its own position detected by each positioning means. Means for extracting information unique to each included position is provided.

[0007]

Each mobile station sequentially detects the cell to which the mobile station belongs and the sector within the cell based on the carrier frequency and level of the radio wave transmitted from each fixed station.
By detecting the distance from the fixed station in each sector based on the level of the radio wave received from the fixed station, the position of the own machine can be automatically changed without waiting for human intervention and half the size of the conventional sector. Can be detected with high positioning accuracy.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the cellular system according to the present invention will be described by taking a case of a product guidance service as an example. Similar to the configuration shown in FIG. 5, the overall configuration of this cellular system is defined by a plurality of fixed stations to which different carrier frequencies are assigned and a plurality of radio stations transmitted by each fixed station. Each cell is divided into a plurality of sector-shaped sectors centered on a fixed station. Mobile units mounted on carts that move across each cell can receive each radio wave of a different carrier frequency being transmitted from the fixed station of each cell by automatically scanning the reception frequency. . Note that the antenna installed in each mobile device may be omnidirectional or directional, but preferably has a multipath compensation function. Further, the wall surface of the sales floor where this cellular system is constructed is preferably covered with a radio wave absorbing material to suppress the reflection of radio waves by the wall surface.

As shown in FIG. 2, each cell is divided into a plurality of sectors by fixing _six directional antennas such that the main lobes A _{1 to} A ₆ are adjacent to each other and overlap each other. A mobile unit installed in a station and mounted on a cart that moves across each sector compares the reception levels of the radio waves transmitted from each of the six directional antennas, and compares the reception level with the antenna that is transmitting the radio wave of the maximum reception level. The antenna which is transmitting the radio wave of the next highest reception level is detected by the antenna identifier added to the signal included in each radio wave.
It is configured to detect the sectors S ₁₂ , S ₂₁ , S ₂₃ ... S ₁₆ . As shown in FIG. 3, each of these twelve sectors depends on whether the reception level of the radio wave transmitted from the fixed station is equal to or higher than a predetermined threshold.
It is divided into a sub-sector H near the fixed station and a sub-sector L far from the fixed station.

Signals transmitted from the six directional antennas of each fixed station are divided into six frames F1 to F6 corresponding to directional antennas 1 to 6 as illustrated in the signal format diagram of FIG. The superframe composed of F6 is repeated, and n (1, 2, 3,...)
The sixth antenna is configured to transmit a signal only to the n-th frame Fn. At the beginning of the frames F1 to F6, a frame synchronization signal SW is arranged, next, an antenna identification slot is arranged, and subsequently, displayed product information of a sector is arranged. In the antenna identification slot, the identifier of each directional antenna is transmitted using, for example, one of the six time slots assigned to each directional antenna. The displayed product information is the product information displayed in the four sub-sectors covered by the directional antenna, and the main lobe A illustrated in FIG.
_The merchandise information displayed in the four sub-sectors S ₁₆ H, S ₁₆ L, S ₁₂ H, and S ₁₂ L covered by the first antenna having 1 is arranged.

A mobile device mounted on a cart moving across each of the cells receives a radio wave including a frame-structured signal transmitted from each fixed station, and determines the current state of the mobile device based on the strength of the received radio wave. The position is detected, a position corresponding to the detected current position is extracted from the displayed product information included in the received signal, and displayed. That is, as shown in the flowchart of FIG. 1, each mobile station firstly changes the reception frequency to each of the radio frequencies assigned to each fixed station, thereby increasing the reception level or increasing the signal reliability. By detecting the frequency of the highest radio wave (for example, having the lowest bit error rate) and referring to a correspondence table between each cell registered in the built-in memory and the radio frequency assigned to each cell, for example, (Step 1)
1).

Next, the mobile station detects the antenna identifier contained in the radio wave having the highest reception level and the antenna identifier contained in the radio wave having the next highest reception level, and registers the antenna identifier in the built-in memory. Positioning between sectors is performed, for example, by referring to a correspondence table between the combination of each antenna identifier and the sector (step 12). In addition, mobile devices
The reception level compares the reception level of the maximum radio wave with a predetermined threshold value, and determines the position in the sector according to the result, that is, in the sub-sector H closer to the fixed station shown in FIG. Positioning is performed to determine whether or not the sub-sector L is located on the far side (step 13). Finally, the mobile device extracts the displayed product information corresponding to the detected position from the displayed product information of the sector included in the radio wave at the maximum reception level (see FIG. 4), and mounts the extracted information on the cart. The display is supplied to the inside display device and displayed (step 14).
Until the end command is detected in step 5, the above processing is repeated.

Although the cellular system according to the present invention has been described above taking the case of a product guidance service using a wireless LAN as an example, the cellular system can be applied to the positioning of a robot car that automatically travels in a warehouse or a factory. it can. In this case, a transmitter / receiver is mounted on the robot car, and the detected position is wirelessly transmitted to a fixed station, and the fixed station receiving the position transmits the detected position to a higher-level device such as a centralized management device via a wired transmission path. It can be configured.

The present invention has been described by taking as an example a configuration in which positioning is performed by combining all the positioning means between cells, the positioning means between sectors in a cell, and the positioning means in a sector. It is also possible to adopt a configuration in which positioning is performed by combining only two.

Further, the simple positioning method according to the present invention can be applied to a mobile position detection method in a mobile communication system such as a car phone or a mobile phone. Further, the cellular system of the present invention can be applied to a traffic information providing system for notifying a vehicle or the like of traffic congestion information or traffic restriction information for each subsector. In such a large-scale cellular system, typically M sectors /
Since a repetitive cluster configuration of N cells is employed, each fixed station transmits a cluster identifier in addition to the above-described antenna identifier, as necessary, in order to identify different cells using the same carrier frequency. Is adopted.

[0016]

As described above in detail, in the cellular system of the present invention, each mobile station sequentially determines the cell to which the mobile station belongs and the sector within this cell according to the level of the radio wave transmitted from each fixed station. Then, one of the two sub-sectors assumed in each sector according to the distance to the fixed station is detected based on the level of the radio wave received from the fixed station. Position automatically without waiting for human intervention and 1/4 of conventional sector size
There is an effect that the detection can be performed based on the positioning accuracy.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining the content of processing executed by a mobile device constituting a cellular system according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an example of a method of dividing each cell constituting the cellular system of the embodiment into sectors.

FIG. 3 is a conceptual diagram showing an example in which each sector constituting the cellular system of the embodiment is divided into sub-sectors.

FIG. 4 is a signal format diagram showing an example of a configuration of a signal transmitted from a fixed station in each cell constituting the cellular system of the embodiment.

FIG. 5 is a conceptual diagram showing an example of a configuration of a general cellular system.

[Explanation of symbols]

C ₁ -C ₆ cell F ₁ to F ₆ fixed station M ₁ ~M ₃ subsidiary unit (mobile station)

Claims (3)

(57) [Claims] A plurality of cells defined by a radio wave range including a signal transmitted from each of a plurality of fixed stations using a different carrier frequency are formed adjacent to each other, and a fixed station in each cell is provided with a plurality of cells. An antenna for transmitting a radio wave including a signal to which a sector identification function is added to each of a plurality of sectors divided in each direction within the own cell with a fixed station as a center, and a mobile device movable across each cell is provided for each cell. In a cellular system for receiving radio waves transmitted from a fixed station and reading signals contained therein, an antenna provided for each fixed station includes a sector identification device.
Multiple sectors adjacent to radio waves containing signals with added capabilities
A plurality of directional antennas radiate over, each mobile station, ship based on the carrier frequency of the received radio wave of the reliability and the appropriate signal included in the level or the radio wave of the radio wave received from the fixed station Inter-cell positioning means for detecting a cell to which the cell belongs ; receiving radio waves transmitted from the fixed station in the positioned cell into each of the sectors;
Cellular system, characterized in that a inter-sector positioning means for detecting the radio wave and the next sector to the apparatus itself belongs in the cell based on the large radio wave of the sector identification features. 2. The mobile device according to claim 1 , wherein the position of the mobile device in each of the detected sectors is determined.
Whether this cell is near or far from the fixed station
The level or reliability of radio waves received from this fixed station.
In-sector positioning means for detecting based on small size is further provided.
A cellular system, characterized in that: 3. The method of claim 1 or 2, wherein each fixed station is assumed to sub-sectors for 2 minutes in accordance with each sector of the local cell to the distance from the fixed station, said each cell, Sarera each cell Means for transmitting a signal including product display information and other information unique to each position determined by the combination of each of the sectors and the respective sub-sectors in each of the sectors; in cellular system characterized by comprising means for extracting a specific signal to each position included in the signal received from the fixed station based on the detected current position.