JPH1023537A - Communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid collision even when a plurality of master sets are in existence by retrieving a carrier idle timing of a transmission channel and starting transmission of a control slot when it existence and selecting another frequency channel when not in existence. SOLUTION: A reception monitor section 18 retrieves a carrier idle timing of a channel from which a control slot is set. A slot transmission reception timing setting section 19 starts transmission of the control slot in a retrieved idle timing. Thus, even when a plurality of master sets sending the control slot through the same channel are in existence, collision is avoided and a slave set recognizes surely its master set. If a radio transmission reception frequency setting section 20 cannot find out the carrier idle timing through all transmission intervals, another frequency channel is selected. Even when lots of master sets are located, collision among the master sets is avoided by retrieving the idle timing over a plurality of frequency channels in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-division multiplex communication device, and more particularly to a communication device which is effective when applied to a private PHS master device.

[0002]

2. Description of the Related Art In a PHS system, for example, a time division multiplexing system in which one radio frequency channel is divided into a plurality of transmission / reception slots on a time axis is adopted (for example, "Nikkei Electronics September, 1994" published by Nikkei BP).
Issue 12 (No. 617), pages 78, 79).

[0003] With this, even when a plurality of private PHS masters are installed in the same area, each PHS master uses the same frequency channel in the same area and independently operates with respect to each slave. Can be secured.

[0004] In this case, each PHS master unit forms a standby state while transmitting a control slot to the slave unit by radio at regular intervals. The control slot contains identification information (ID) of the master unit, and its transmission timing serves as a timing reference for transmission / reception slot transmission between the master unit and the slave unit. By receiving the control slot, the child device can identify a specific parent device and synchronize transmission and reception timing with the specific parent device.

[0005]

In this type of communication device, a certain synchronous relationship based on the timing of the control slot is established between the parent device and the child device, which are identified by the ID. However, the synchronization relationship between the base units is not considered. That is, in the case of a private PHS master, a plurality of masters are independently installed in the same area, and are not synchronously connected to each other. Therefore, although the time interval of the control slot in which each base station transmits a radio signal is adjusted to a fixed time according to the standard or the like,
The timing of the transmission is randomly determined for each parent device, for example, according to the activation timing of the parent device.

For this reason, when the number of master units installed in the same area increases, the chances of collision of control slots transmitted by each master unit by radio coincidence increase. Here, if the control slots transmitted by the two master units collide with each other at the same timing, the slave units of each master unit cannot normally receive the control slot from the master unit. Machine cannot be identified.

[0007] Once this collision state occurs, it is difficult to escape. This is because even if there is no synchronization relationship between the two base units, the time intervals of the control slots transmitted from the respective base units of the same system configuration to each other are uniform, so that the first control slot If they collide at the same timing, there is a very high possibility that the next control slot will also collide at the same timing.

As a result, the present inventors have apparently caused a problem that the slave unit may not be able to recognize the master unit for a long time even though the master unit is in the standby state. And it was.

SUMMARY OF THE INVENTION It is an object of the present invention to ensure that a slave in a standby state is recognized by a slave.

[0010]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to a time-division multiplex communication apparatus which forms a standby state while transmitting a control slot to a slave unit by radio at regular intervals. And performing a reception monitor for searching for a carrier vacancy timing on the transmission scheduled frequency channel of the control slot at startup, and starting transmission of the control slot at the carrier vacancy timing searched by the reception monitor. It is.

This prevents the control slot from colliding at the same timing with another master unit in the same area, and allows the slave unit to reliably recognize the standby state. A communication device is obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a time-division multiplex communication apparatus for forming a standby state while transmitting a control slot to a slave unit by radio at regular intervals. Receiving monitor means for searching for a carrier vacant timing on the transmission scheduled frequency channel of the control slot at the time of startup; and timing setting means for determining the transmission start timing of the control slot from the carrier vacant timing searched for by the monitor means. Even if there are a plurality of base units in the same area that wirelessly transmit control slots on the same frequency channel, collision of control slots among the plurality of base units is avoided, This has the effect that the slave can be reliably recognized by the slave.

According to a second aspect of the present invention, in addition to the first aspect, when the carrier vacancy timing is not detected throughout the transmission interval of the control slot, the transmission scheduled frequency channel of the control slot is changed to another frequency channel. A frequency setting means for switching, so that even when a large number of master units are densely arranged in the same area, a control slot collision between the master units is avoided, and the master unit is controlled by the slave unit. This has the effect that the recognition of the character can be surely performed.

According to a third aspect of the present invention, there is provided a communication device of a time division multiplexing system which forms a standby state while transmitting a control slot to a slave unit by radio at regular intervals, wherein a carrier free frequency A reception monitoring unit for searching for a channel; and a frequency setting unit for forming the reception standby state on the available carrier frequency channel searched for by the monitoring unit. Has the effect of avoiding collision of control slots among the plurality of master units and ensuring that the slave unit recognizes the master unit.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 shows a schematic configuration of a communication device to which the technology of the present invention is applied.

The communication device shown in FIG. 1 constitutes a private PHS master device, and includes a radio transmission / reception antenna 11, a radio transmission / reception unit 12, a time division multiplexing control unit (TDD control unit) 13,
An ADPCM codec 14, a line control unit 15 connected to the public telephone line L, a handset 16, an operation unit 17, a reception monitor unit 18 for detecting a carrier vacancy, a slot transmission / reception timing setting unit 19, a radio transmission / reception frequency setting unit 20, and the like. Have.

The standard functions of the PHS base unit include a radio transmitting / receiving antenna 11, a radio transmitting / receiving unit 12, a time division multiplexing control unit 13, an ADPCM codec 14, a line control unit 15, a handset 16, a control unit 17, and the like. I have.

In the standard function of the PHS master, a standby state is formed while transmitting control slots to the slaves by radio at regular intervals. The control slot contains the identification information (ID) of the master unit, and the transmission timing is used as a timing reference for the transmission / reception slot between the master unit and the slave unit. By receiving the control slot, the child device can identify a specific parent device and synchronize transmission and reception timing with the specific parent device. This makes it possible to secure a bidirectional communication channel with one radio frequency channel. In this case, a plurality of sets of the transmission / reception slots are set for each frequency channel, so that one frequency channel can be shared by a plurality of PHS master units and slave units in the same area.

Further, in the communication device shown in FIG. 1, in addition to the configuration of the above-described standard function, a reception monitor unit 18, a slot transmission / reception timing setting unit 19, a radio transmission / reception frequency setting unit 20, and the like for detecting an empty carrier are provided. With this configuration, even when there are a plurality of master units that transmit control slots wirelessly in the same frequency channel in the same area, collision of control slots among the plurality of master units can be avoided, and the master unit Make sure the machine is recognized.

In this case, when the device is started, the reception monitor unit 18 searches for a carrier vacant timing in a frequency channel from which a control slot is to be transmitted. The slot transmission / reception timing setting section 19 starts transmission of the control slot at the carrier empty timing searched by the monitor section 18. As a result, even if there are a plurality of master units that wirelessly transmit control slots on the same frequency channel in the same area, collision of control slots among the plurality of master units is avoided, and the master unit Can be surely recognized.

The radio transmission / reception frequency setting unit 20 switches the transmission scheduled frequency channel of the control slot to another frequency channel when the carrier vacant timing is not detected in all transmission intervals of the control slot. That is, a carrier empty timing is searched over a plurality of frequency channels. As a result, even if a large number of master units are densely arranged in the same area,
By avoiding a control slot collision between the parent devices, the child device can more reliably recognize the parent device.

FIG. 2 is a flowchart showing the configuration of a communication device according to the present invention, focusing on its operation. In the figure, when the operation is started by turning on the start switch (power switch), first, the frequency channel (fx)
Setting and timing position dt of control slot CS1
Initialize the settings for each.

Next, reception monitoring of the carrier is performed at the set frequency channel and the set timing position. This reception monitoring is performed based on the reception level of the wireless transmission / reception unit. If a wireless signal (carrier) of a certain level or more is detected by the wireless transmission / reception unit, it is determined that no carrier is available, and otherwise, it is determined that a carrier is available.

Here, if a carrier vacancy is detected, transmission of a control slot is started at the timing of the detected carrier vacancy, and a transition is made to a standby state. If no carrier vacancy is detected, the detection timing position is shifted by a fixed difference △ dt, and the carrier vacancy is detected again at the shifted timing position. In this way, the search for a carrier vacancy is performed while shifting the detection timing position stepwise.

As a result of the above-described carrier empty search, if no carrier empty is detected over all transmission intervals of the control slot, the transmission scheduled frequency channel of the control slot is switched to another frequency channel. Then, the above-described series of carrier empty search is performed on the switched frequency channel. This switching of the frequency channel is repeated until a carrier vacancy is detected.
If no carrier vacancy is detected in all frequency channels, the process returns to the first frequency channel and repeats the same operation.

As described above, the carrier position is searched for while sequentially updating the timing position and the frequency channel.
Transmission of a control slot is started at the time when a carrier vacancy is detected, and a transition is made to a standby state. As a result, as described above, even if a large number of master units are densely arranged in the same area, it is possible to avoid a control slot collision between the master units and to reliably recognize the master unit by the slave units. Can be done.

FIG. 3 is a time chart showing an operation example of the above-mentioned carrier empty search. In the example shown in the figure, when the reception of a carrier vacancy is detected at the timing position t1, the control slot CSx from another master unit is received at the timing position t1, so that the next control signal is shifted by dt therefrom. At the timing position t2, the reception detection of the carrier vacancy is performed again, and the carrier vacancy is detected there. Then, transmission of the control slot is started based on the detected carrier empty timing position t2.

In the above description, the carrier empty search is performed while shifting both the timing and the frequency channel.
Alternatively, even by shifting only the frequency channel, the effect of avoiding control slot collision between the master units can be obtained.

[0029]

As described above, according to the present invention, it is possible to prevent a control slot from colliding at the same timing with another master unit in the same area, and to prevent a collision from a slave unit. An advantageous effect that the master device can be surely recognized is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a communication device to which the technology of the present invention is applied;

FIG. 2 is a flowchart showing the configuration of a communication device according to the present invention focusing on its operation.

FIG. 3 is a time chart showing an operation example of carrier empty search;

[Explanation of symbols]

 L Public telephone line 11 Radio transmission / reception antenna 12 Radio transmission / reception unit 13 Time division multiplex control unit (TDD control unit) 14 ADPCM codec 15 Line control unit 16 Handset 17 Operation unit 18 Reception monitor unit for carrier empty detection 19 Slot transmission / reception timing Setting unit 20 Wireless transmission / reception frequency setting unit

Claims (3)

[Claims] 1. A time-division multiplexing communication device for forming a standby state while transmitting a control slot wirelessly to a slave unit at predetermined time intervals, wherein a carrier is transmitted at a scheduled transmission frequency channel of the control slot at the time of startup. A communication device comprising: reception monitor means for searching for an idle timing; and timing setting means for starting transmission of the control slot at the carrier idle timing searched by the monitor means. 2. A frequency setting means for switching a frequency channel to be transmitted in the control slot to another frequency channel when a carrier empty timing is not detected throughout the transmission interval of the control slot. 2. The communication device according to 1. 3. A time-division multiplexing communication device for forming a standby state while transmitting a control slot wirelessly to a slave device at predetermined time intervals, wherein a reception monitor means for searching for a carrier-free frequency channel at startup. And a frequency setting means for forming the reception standby state on the carrier free frequency channel searched by the monitoring means.