JPS62107543A - Radio communication equipment - Google Patents

Abstract

PURPOSE:To prevent the collision with other system and to utilize a frequency effectively by providing a reception frunction to detect a carrier of the same frequency as the transmission frequency, confirming the absence of the carrier within a random time after no carrier is detected to apply the transmission. CONSTITUTION:A clock signal (g) from a clock generating circuit 73 is used as a clock of a counter 72. When a data memory 4 sends a data and other system does not use the same frequency and a carrier sense request signal (b) is made active, an initial timer value (e) to a counter 72 is set by an initial timer value (time t) generating circuit 75 and the counter 72 starts counting. After the counter 72 counts the initial timer value (t), a transmission enable signal (h) is generated, an F/F71 is reset to bring the data memory 4 into the transmission enable state. When the data memory 4 receives the transmission enable signal (h), the switch 2 is thrown to the position of the transmission section 3 immediately, the transmission section 3 is set, the data stored in the data memory 4 is sent to the transmission section 3, from which the data is set in air.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wireless communication device, and particularly to a wireless communication device that uses the same frequency under conditions where a plurality of systems share the same frequency.

[Conventional technology]

Radio waves can generally only be used by one system at a time on the same frequency. Normally, one system monopolizes this radio wave resource, or multiple systems use it through time sharing. Methods for time sharing between multiple systems will become increasingly important in the future in order to effectively utilize the scarce resources of radio waves.

[Problem that the invention seeks to solve]

However, when these multiple systems share and use one frequency, there is an inconsistency in that, unless there is a means to control the multiple systems, transmissions will inevitably occur simultaneously and cause collisions. In a system where humans directly talk to each other using their voices, such as communication communications, humans can immediately tell that there is interference as soon as they hear it, and can take measures such as trying to transmit again after the other system's radio waves have disappeared. In data communications that are not directly involved, collisions such as the one described above can be fatal, especially in a unidirectional rather than bidirectional system such as a paging system, as it is unclear whether the receiver was able to actually receive the data, and even in a bidirectional system. If there are many collisions, the number of retransmissions will increase accordingly, resulting in poor efficiency.

[Failure to solve the problem]

The present invention provides a wireless communication device that transmits data or audio signals, etc., which has a receiving function for detecting a carrier having the same frequency as the transmission frequency, and
When transmitting a signal, it first monitors for a certain period of time whether or not there is a carrier with the same frequency, and if it is not detected, it moves on to the sending operation, but if a carrier is detected within a certain period of time, it waits until it is no longer detected. Then a random (
An object of the present invention is to provide a wireless communication device that prevents collisions with other systems and utilizes frequencies as effectively as possible by performing a sending operation after confirming that there is no carrier within a random) time. Furthermore, by temporarily storing data, audio signals, etc. until the above-mentioned transmission operation is started, it becomes a standby type, which further improves efficiency.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is an example of a wireless communication device implementing the present invention.

1 is a transmitting/receiving antenna, 2 is a transmitting/receiving switch, 3 is a transmitter, 4 is a data memory for temporarily storing data, 5 is a receiver for carrier sense, and 6 is a carrier detection signal output The squelch circuit 7 is a control section that controls the timing of data transmission. The control section 7 further includes 70 knobs (Ii'/F).
71, a counter 72, a clock generation circuit 73, a NAND gate (NAND) 74, an initial timer value generation circuit 75, and a random timer value generation circuit 76.

FIG. 2 is a timing chart when the communication device shown in FIG. 1 attempts to send data and there is no other device using the same frequency. First, when data to be transmitted from an external device enters the data memory 4, the data memory 4 issues a pulse of a transmission request signal a to the control section 7. The transmission request signal a is held by Ii''/F71 and becomes a carrier sense request signal (active HI
GH).

The switch 2 is normally placed on the side of the receiving section 5, and the presence or absence of radio waves (carriers) of other systems is detected by checking the antenna 1° and the receiving section 5.
It is monitored by squelch 6, and the carrier detection signal C
is supplied to the control unit 7 (L when carrier is present).
OW). In the control 7, both the carrier sense request signal and the carrier detection signal C are HI.
Only when the signal is GH, the count request signal d becomes LOW (active) by the NAND 74, and the counter 72 counts the time when there is no carrier.

The clock of the counter 72 uses the clock signal g from the clock generation circuit 73. When the data memory 4 attempts to transmit data, when it issues a transmission request signal, if no other system is using the same frequency,
When the carrier sense request signal becomes active,
The initial timer value (time t) generation circuit 75 sets the initial timer value e to the counter 72, and the counter 72 starts counting. After counting the initial timer value t, the counter 72 generates a transmission permission signal, resets the F/P 71, and puts the data memory 4 in a transmission permission state. When the data memory 4 receives the transmission permission signal, it immediately flips the switch 2 to the transmitter 3 side and turns on the transmitter 3.
The data stored in the data memory 4 is transmitted to the transmitter 3.
The data is sent into the air from antenna 1.

Next, FIG. 3 is a timing chart when another system uses the same frequency when the transmitter is about to send data. The carrier sense request signal S becomes active from the transmission request signal aK, but at this time, if the carrier detection signal C is i, ow (that is, another radio wave (carrier) is detected/output), the NAND 74 starts counting. Since the request signal d does not become active, the initial timer value e is generated by the initial timer value generation circuit 75.
It is set to 2 but does not count. When the carrier detection signal C is HIG)-1 (that is, there are no other radio waves), the count request signal d becomes active for the first time, and this time, the random timer value generation circuit 76 sets the random timer value f to the counter 72. The counter 72 counts when the random timer value reaches the interval t'Xn), and when the count ends, generates a transmission permission signal. Here, t and t' may be the same value, and may be the minimum time required for carrier sensing. Also, n is 1, 2, etc.
The more you add 3m, the more you can prevent collisions, but if you add too much, you will lose time.

〔Effect of the invention〕

The wireless communication device implementing the present invention has been described above, and the specific effects are shown in a timing chart in FIG. The data transmission request time is expressed as tTI” tT3,
The HIGH level indicates that data is being transmitted. Here, the systems that interfere with each other are system 1, system 2, and system 2. Suppose there are three systems 30. First, when the system 1 receives a transmission request and other systems are not transmitting, it starts transmitting at the shortest carrier sense time t. If during this time, system 2. When each system 3 receives a transmission request, it waits until the transmission of system 1 ends, and when it ends, it performs carrier sensing using a random timer value (t'xnl, t'Xn2), so if the timer value happens to be short, system 2
The system 3 starts transmitting first, and the system 3 starts transmitting after the system 2 finishes transmitting, thereby preventing data collision.

As described above, according to the present invention, carrier sensing is performed when a data transmission request is made, and if there are no other carriers, data can be transmitted in the shortest time required for carrier sensing, and if there are other carriers, the carrier sensing time becomes random. , which has the effect of making effective use of radio waves and preventing data collisions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a wireless communication device that is an embodiment of the present invention, FIG. 2 is a timing chart when there is no other carrier at the time of the data transmission request in FIG. 1, and FIG.
FIG. 4 is a timing chart diagram when another carrier is detected at the time of the data transmission request shown in FIG. 1...Antenna, 2...Transmission/reception selector switch, 3...Transmission unit, 4...
Data memory, death...Receiving section, 6...Squelch, 7.Old control section, 71...
Flip-flop, 72... group-counter, 73...
...Clock generation circuit, 74...NANDG
ATE, 75...Initial timer value generation circuit, 76
...Random timer value generation circuit. -9゛- 1t 1 t 1

Claims (1)

[Claims] In a wireless communication device that transmits data or voice signals, etc. used under conditions where each system shares the same frequency and operates independently of each other, a carrier having at least the same frequency as the transmission frequency is used. It has a reception function for detection, and when trying to transmit data or audio signals, it first monitors the carrier of the same frequency for a certain period of time, and if it is not detected, it moves to the transmission operation, and if the carrier of the same frequency is detected. Once detected, wait until it is no longer detected,
A wireless communication device characterized in that it moves to a transmitting operation after confirming that there is no carrier within a random time period after it is no longer detected. (2) The wireless communication device according to claim 1, wherein the data or audio signal is temporarily stored until the transmission operation is started.