JPH02288625A - Multiple access communication system - Google Patents

Abstract

PURPOSE:To reduce the line occupancy time due to retransmission and to improve the line operating efficiency by decreasing the length of a signal to be sent when a data sent from a terminal station collides with a signal from other terminal station or an error takes place during the transmission, and the terminal station sends the data newly. CONSTITUTION:A control station 1 supervises whether or not a preamble signal is detected from an incoming line 3 while sending an idle signal to an outgoing line 4, and when th preamble signal is detected from the incoming line 3, a busy signal is sent to the outgoing line 4. When the station 1 receives at least an ID signal, the signal instincts a terminal station 2 which made transmission to send the remaining signal not yet received and the terminal station 2 receiving the instruction places the preamble signal to send only the remaining signal. Thus, the time occupied by the line due to the retransmission is reduced and the line utilizing efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a multiple access communication system applied to a wireless communication system such as a car telephone.

(Prior Art) As shown in FIG. 7, in a wireless communication system such as a car phone, a wireless communication line is formed between one control station 1 and a plurality of terminal stations 2 to exchange signals. It is configured.

By the way, in such a wireless communication system, the control station 1
It is necessary to exchange not only call signals but also predetermined data signals between the terminal station 2 and each terminal station 2, and as shown in the figure, these data signals are exchanged between the common uplink line 3 and the downlink line. A multiple access communication method is adopted using a two-way wireless communication line consisting of four. Furthermore, the signal transmitted from the terminal station 2 to the control station 1 via the uplink 3 is as follows:
As shown in FIG. 8, basically, the preamble signal 5,
It is composed of an ID signal 6 indicating the ID of the transmitting terminal station, a data length signal 7 indicating the data length, and a data signal 8.

Signals are exchanged using these uplinks 3 and downlinks 4 as shown in FIG. 9.

That is, when data is generated at a certain terminal station 2 at time TI, the terminal station 2 detects the state of the downlink 4. In this case, the state of the downlink 4 is an idle signal (a signal issued from the control station 1 indicating that the line is idle), so the terminal station 2 receives the preamble signal 5 from time T2, The IDrCi' signal 6, the data length signal 7 and the data signal 8 are continuously sent to the uplink 2.

On the other hand, when the control station 21 detects the preamble signal 5 from the uplink 4 at time T3, the control station 21 converts the downlink 4 signal from an idle signal to a G signal (indicating that the line emitted from the control station 1 is in a blocked state). signal). Then, at time T4, when the reception of all data is completed, an ACK signal is sent to the downlink 4, and at time T5,
The signal on the downlink 4 is changed from a busy signal to an idle signal again.

Note that the terminal station 2 recognizes that the data has correctly arrived at the control station 1 by detecting an ACK signal from the downlink 4 at time T6.

By the way, in such a multiple access communication system, all of the various signals shown in FIG. 8 may not reach the control station 1 due to signal collision in the downlink 4, transmission path Z4, etc. In this case, in the conventional system, the signals shown in FIG. 8 are sent out again in the procedure shown in FIG. 9.

However, since the signals shown in FIG. 8 have considerable lengths, such as the preamble signal 5, the own ID signal 6, the data length signal 7, and the data signal 8, the downlink 4 is occupied by such retransmission. There is a problem in that it takes a long time for the line to be used, which in turn leads to a deterioration in the efficiency of line usage.

(Problem to be Solved by the Invention) As described above, in the conventional multiple access communication system, when all of the various signals do not reach the control station due to signal collisions, transmission path errors, etc., all of the various signals are re-signaled. Therefore, there is a problem in that the line is occupied for a long time due to retransmission, which in turn leads to deterioration in line usage efficiency.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to realize a multiple access communication system that can shorten the time that a line is occupied by retransmission and improve the efficiency of line usage.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides that one control station and a plurality of terminal stations are connected by a common bidirectional communication line, and the terminal stations transmits a signal prefixed with a preamble signal and including at least its own ID signal and data signal, and when the control station detects the preamble signal, it notifies other terminal stations of transmission prohibition and transmits the signal from the terminal station. In a multiple-access communication car system that receives a signal of
When at least an ID signal can be received from the terminal station,
The terminal station that transmitted the signal is instructed to transmit the remaining signal that was not received, and the terminal station to which the instruction is given transmits only the remaining signal with a preamble signal prefixed. .

(Function) In the present invention, when the control station is able to receive at least an ID signal, it instructs the terminal station that transmitted the signal to transmit the remaining signals that were not received; Since the terminal station prefixes the preamble signal and transmits only the remaining signals, the time during which the line is occupied by retransmission can be shortened and the efficiency of line use can be improved.

(Example) Next, the present invention will be described in detail with reference to the drawings.

The configuration of the wireless communication system according to the embodiment of the present invention is the same as that shown in FIG. 7 of the conventional example, and the basic format of the signal sent from the terminal station is also the same as shown in FIG. 8. The control procedures related to transmission and reception between the control station 1 and the terminal station 2 are different.

FIG. 1 is a flowchart showing the control related to transmission and reception of the terminal station 2 in this embodiment, and the control procedure of the terminal station 2 will be explained according to this diagram.

When data is generated at terminal station 2, terminal station 2 transmits data to downlink 4.
(Step 101). Here, when a busy signal is detected, an appropriate time delay is applied (step 10).
2) Monitor the downlink 4 again (step 101)
. On the other hand, when an idle signal is detected, the number of times the terminal station 2 is currently transmitting data is detected (step 103). And if it is L1 once,
The preamble signal 5, ID signal 6, data length signal 7 and data signal 8 are continuously sent to the uplink 3 (step 104). If it is the second time, preamble signal 5, I
The D signal 6 and data signal 7 are continuously sent to the uplink 3 (step 105). If it is the third time or more, the preamble signal 5 and ID signal 6 are continuously sent to the uplink 3 (step 10B). Thereafter, it waits for a response signal from control station 1 (step 107).

If a response signal from the control station 1 is detected on the downlink 4 and the response signal is an ACK signal (step 10B),
End data transmission.

Also, if the response signal is a reservation confirmation signal (step 10
9) According to the contents of the reservation confirmation signal, if the reservation confirmation signal specifies the data length, after sending the preamble signal 5 and data signal 8 to the uplink line 3 (step 1
10) Waits again for a response signal from the downlink 4 (step 107). If the reservation confirmation signal does not specify the data length, the preamble signal 5, data length signal 7, and data signal 8 are sent to the uplink 3 (step 110).
Waits again for a response signal from the downlink 4 (step 107)
).

Furthermore, if the response signal is a NAK signal (step 111
), an appropriate time delay is applied (step 102), and the above control procedure is repeated from the initial monitoring of the downlink 4 (step 101).

FIG. 2 is a flowchart showing the control related to transmission and reception of the control station 1 in this embodiment, and the control procedure of the control station 1 will be explained according to this diagram.

Control station 1 normally sends an idle signal to downlink 4 (step 201) and monitors whether preamble signal 5 is detected from uplink 3 (step 202).

When the preamble signal 5 is detected from the uplink 3, a g signal is sent to the downlink 4 (step 2).
03). After this, it is determined whether or not the ID signal 6 is detected (step 204). If the ID signal 6 is not detected, the signals from the terminal station 2 have collided, or an error has occurred in the transmission path. (step 205), N
The AK signal is sent to the downlink 4 (step 20G).

On the other hand, if ID signal 6 is detected, it is determined whether data length signal 7 is detected (step 207).

If the data length signal 7 is detected, it is determined whether the data signal 8 is detected (step 208).
, if a data signal 8 is detected, an ACK signal is sent to the downlink 4 (step 209), and then an idle signal is sent to the downlink 4 again (step 201).
).

Further, if the data length signal 7 is not detected (step 207), only the terminal station 2 indicated by the previously detected ID signal 6 is recognized as holding the data, and the terminal station 2 is stored for a preset time. After transmitting to the downlink 4 a "reservation confirmation signal without data length specification" that allows the transmitting terminal station 2 to occupy the uplink 3 for a limited time and prohibits transmission by other terminal stations 2 (step 210 ), sends a busy signal to the downlink 4 (step 211). After that, it waits for a signal from the transmitting terminal station 2 and determines whether or not the preamble signal 5 is detected (step 21.2). If the preamble signal 5 is detected, the data length signal 7 is again transmitted. It is determined whether or not it has been detected (step 207).

Furthermore, if the data signal 8 is not detected (step 20g), it is determined that the terminal station 2 indicated by the previously detected ID signal 6 holds data of the length indicated by the data length signal 7. "With data length specified", the transmitting terminal station is allowed to occupy the uplink 3 only for the length of time indicated by the data length signal 7, and the transmission of other terminal stations 2 is prohibited. After sending the reservation confirmation signal to the downlink 4, a busy signal is sent to the downlink 4 (step 2
13). Thereafter, it waits for a signal from the transmitting terminal station and determines whether or not the preamble signal 5 is detected (step 214). If the preamble signal 5 is detected, the data signal 8 is detected again. A determination is made as to whether it is 1 or not (step 208).

In this embodiment, by performing the control procedures related to transmission and reception between the control station 1 and the terminal station 2 in this manner, the operation of the entire system is as follows.

First, when the signals shown in FIG. 7 are normally sent from the terminal station 2 to the control station 1 at once, the process is performed as shown in FIG. 9. In this respect, there is no difference from that shown in the conventional example, but there is a difference in the case where not all of these signals reach the control station 1 due to signal collision, transmission path error, or the like.

That is, FIG. 3 is a time chart when a transmission path error occurs.

At time TI, when data is generated at a certain terminal station 2, the terminal station detects the state of the downlink 4. Here, since the downlink 4 is in the idle signal state, the preamble signal 5, own ID signal 6, data length signal 7, and data signal 8 are continuously sent to the uplink 3 from time T2.

On the other hand, when control station 1 detects a preamble signal from uplink 3 at time T3, it changes the signal on downlink 4 from an idle signal to a busy signal. Here, time T
4, when it is detected that there is a transmission path error in the data signal 8 from the terminal station, the terminal station 2 indicated in the previously detected ID signal 6 transmits the length indicated in the data length signal 7. It only recognizes that it holds data. Then, a "reservation confirmation signal with data length specification" is issued which allows the transmitting terminal station to occupy the uplink 3 for a period of time indicated by the data length signal 7 and prohibits transmission by other terminal stations 2. After sending the signal to the downlink 4, the signal on the downlink 4 is set as a busy signal.

After that, at time T5, when the terminal station 2 detects the reservation confirmation signal, the terminal station 2 realizes that its own ID signal 6 and data length signal 7 have correctly reached the control station 1, but the data signal 8 is For some reason, at the same time as recognizing that the control station 1 has not been reached, the uplink 3 transmits the data length signal 7.
It recognizes that it has been assigned to its own station for the length indicated in .

Then, from time T6, the preamble signal 5 and data signal 8 are continuously transmitted again.

Thereafter, when control station 1 completes receiving all data at time T7, it sends an ACK signal to downlink 4, and at time T8, changes the signal on downlink 4 from a busy signal to an idle signal again.

Then, at time T9, the terminal station 2 detects an ACK signal from the downlink 4, thereby recognizing that the data has correctly arrived at the control station 1.

FIG. 4 is a time chart showing another example when a transmission path error occurs.

At time Tl, when data is generated at a certain terminal station 2, the terminal station detects the state of the downlink 4. in this case,
Since it is in the idle signal state, the preamble signal 5, own ID signal 6, data length signal 7, and data signal 8 are continuously sent to the uplink 3 from time T2.

On the other hand, when control station 1 detects preamble signal 5 from uplink 3 at time T3, it changes the signal on downlink 4 from an idle signal to a busy signal. Here, at time T4, if it is detected that there is a transmission path error in the part of the data length signal 7 from the terminal station, the previously detected I
It only recognizes that the terminal station 2 indicated by the D signal 6 holds some data, and allows the transmitting terminal station to occupy the uplink 3 for a preset time. After transmitting to the downlink 4 a "reservation confirmation signal without data length specification" that prohibits transmission from other terminal stations 2, the signal on the downlink 4 is made into a busy signal.

After that, at time T5, when the terminal station 2 detects the reservation confirmation signal, the terminal station 2 realizes that the ID signal 6 of its own station has correctly reached the control station 1, but the data length signal 7 and the data signal 8 are not correct. For some reason, the station recognizes that it has not reached the control station 1, and at the same time recognizes that the uplink 3 has been allocated to its own station for a preset time. Then, from time T6, the preamble signal 5 and data signal 8 are continuously transmitted again.

After that, when the control station 1 completes reception of all data at time T7, it sends an ACK signal to the downlink 4,
At time T8, the signal on the tri-line 4 is changed from a busy signal to an idle signal by +IG.

Then, at time T9, the terminal station 2 detects an ACK signal from the downlink 4, thereby recognizing that the data has correctly arrived at the control station 1.

Note that if the length of the data signal 8 is sufficiently shorter than the preset length, the control station 1 sends the busy signal to the downlink 4 more than necessary when transmitting data starting from time T6.
It will be sent to In order to avoid this, for example, as shown in FIG. 5, the preamble signal 5, the data length signal 7, and the data signal 8 may be continuously sent out again at the time of sending out from time T6.

FIG. 6 is a time chart showing an example when a collision occurs.

At time TI, data is generated at terminal station A, and at time T
2, when data is generated at terminal station B, the state of downlink 4 is detected between both terminals. Here, since the terminal station A is in the idle signal state at each time TI and T2, from time T3, the preamble signal 5a,
The terminal station B continuously sends its own ID signal 6a, data length signal 7a, and data signal 8a to the uplink 3, and from time T4, the terminal station B transmits the preamble signal 5b and its own ID signal 6b.
, data length signal 7b, and data signal 8b are continuously sent to the uplink 3.

On the other hand, when the control station 1 detects the preamble signal 5a from the uplink 3 at time T5, it changes the signal on the downlink 4 from an idle signal to a busy signal, but at time T6
Since the ID signal cannot be detected, it is recognized that the signal of terminal station A and the signal of terminal station B have collided or that there is a transmission path error. Therefore, after sending the NAK signal to the downlink 4, the signal on the downlink 4 is made an idle signal at time T7.

After this, at time T8, when each terminal station 2 detects the NAK signal, terminal station A and terminal station B receive the signal from the control station 1.
It recognizes that the data has not been reached at all, and after applying an appropriate time delay, attempts to send the data again. For example, at time T9, when terminal station A attempts to retransmit data, the terminal station detects the state of downlink 4. Here, since it is in the idle signal state and is being sent twice, from time TIO, the preamble signal 5a and the own station's I
The D signal 6a and the data length signal 7a are continuously transmitted to the uplink 3.
When the "reservation confirmation signal with data length specification" is detected from the downlink 4 at time T11, the preamble signal 5a and the data signal 8a are transmitted. On the other hand, terminal station B attempts to retransmit the data at time T12, but since the state of downlink 4 is a busy signal, terminal station B again applies an appropriate time delay.

As described above, according to this embodiment, when a terminal station sends data, if it collides with a signal from another terminal station or an error occurs during transmission, and the terminal station sends the data again, Since the length of the signal is shortened, the time that the line is occupied by retransmission can be shortened, and the efficiency of line use can be improved.

[Effects of the Invention] As explained above, according to the present invention, when a control station is able to receive at least an ID signal from a terminal station, it transmits the remaining unreceived signals to the terminal station that transmitted the signal. Since the terminal station to which the instruction has been given prefixes the preamble signal and only transmits the remaining signals, the time that the line is occupied by retransmission is shortened.
It is possible to improve line usage efficiency.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing control of a terminal station according to the present invention, and FIG.
Figure 3 is a flowchart showing the control of the control station according to the present invention, Figures 3 to 5 are time charts in the case of a signal transmission path error according to the present invention, and Figure 6 is a diagram showing the control of the signal according to the present invention. Figure 7 is a diagram showing the configuration of the wireless communication system; Figure 8 is a diagram showing the basic format of the signal sent by the terminal station; Figure 9 is the time chart when the signal is normal. FIG. l...control station, 2...terminal station, 3...uplink,
4... Downlink, 5... Preamble signal, 6...
ID signal, 7...data length signal, 8...data signal.

Claims (1)

[Scope of Claims] One control station and a plurality of terminal stations are connected by a common bidirectional communication line, and the terminal station receives a signal prefixed with a preamble signal and including at least its own ID signal and data signal. In the multiple access communication system, the control station transmits a signal from the terminal station, and when the control station detects the preamble signal, notifies other terminal stations of transmission prohibition and receives the signal from the terminal station. When at least an ID signal can be received, the terminal station that transmitted the signal is instructed to transmit the remaining signals that were not received, and the terminal station to which the instruction was given prefixes the preamble signal to the remaining signals. A multiple access communication method that is characterized by transmitting only the following signals.