JPH01204546A - Retransmission control system - Google Patents

Abstract

PURPOSE:To improve the data transmission efficiency by adding a signal of several bits to a polling signal so as to attain retransmission instruction (transmission packet number instruction) to a terminal equipment. CONSTITUTION:A bit instructing a transmission packet number is provided in a polling signal calling each terminal equipment and inviting the transmission. The system is controlled so that a terminal equipment retransmits an instructed packet by the same packet number is represented again in the packet number sent when the succeeding polling is applied to the terminal equipment when no data is received or when there is an error in a data from the terminal equipment applied with polling. Thus, it is not required to transmit/receive a control packet such as inverted transmission right or instruction of retransmission to attain the efficient data transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a retransmission control method, and particularly to a retransmission control method in wireless packet transmission using polling.

[Conventional technology]

In a system in which a terminal performs half-duplex packet data transmission by polling, the terminal has the right to transmit until all transmissions are completed and does not perform any receiving operations other than polling. When the base station receives data from a terminal and an error occurs in a packet, the control method is as shown in Japanese Patent Application No. 161160/1983, when a polling signal is sent to each terminal to invite transmission. If there is an error in the data from the polled terminal, by setting the retransmission instruction bit the next time the terminal is polled, the terminal will be able to read the previous packet. The system performs control to retransmit the data. This will be explained with reference to FIG.

FIG. 2 shows terminal 1. FIG. 11 is a sequence diagram showing an example in which an error is detected when data (#l data [2]) for the second polling is received by the system side.

In the figure, P#1. P#2 is a polling signal for terminals 1 and 2, and #1 data [1].

[2] is the packet data order from terminal 1, #2 data m, [2] is the packet data order from terminal 2, P#
1 10N indicates a retransmission instruction polling signal for terminal 1.

In FIG. 2, the system sets a retransmission instruction beep)N together with P#in the next polling signal for terminal 1, and transmits P#1+N. When terminal 1 receives this signal and detects that the retransmission instruction bit is set, it retransmits the previous data.

According to the above-mentioned method, if the base station side detects an error when receiving data, it has the ability to have the terminal side retransmit it, but if the base station side cannot receive the data, it cannot retransmit it. This is illustrated using FIG. FIG. 3 is a sequence diagram when received data cannot be received in the conventional system. In this case, the base station cannot recognize whether the terminal has transmitted in response to the second polling P#1. Therefore, the base station sends polling P#1 again. When the terminal side always sends #1 data [2], #1 is sent for the third polling.
Data [3] will be sent.

At this time, packet loss occurs during reception on the base station side. Therefore, it is a very complicated process for a terminal to send a retransmission request to retransmit only a specific packet after transmitting all packets, and the base station must take the right to transmit during the terminal's transmission. (This is called reversal of transmission rights.)
, issuing a retransmission request and retransmitting out-of-order packets is also called transmission right reversal processing. ), which has the serious drawback of requiring extra packets and reducing data transmission efficiency.

[Means to solve the problem]

According to the present invention, in a wireless packet transmission system in which a base station communicates with a plurality of terminals using polling, a bit indicating a packet number to be transmitted is provided in a polling signal that calls each terminal and invites transmission. If there is an error in the data from the polled terminal or the data has not been received, the terminal is instructed to do so by indicating the same packet number again in the packet number to be sent when polling the terminal next time. A retransmission control method is obtained, which is characterized by performing control to retransmit packets that have been received.

〔Example〕

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

FIG. 1 is a sequence diagram of the retransmission control method of the present invention, where P#IPK(m) and P#2PK(n) indicate polling signals for terminal 1 and terminal 2, respectively.

Here, PK (> indicates the packet number. The packet number is cycled four times. #1 data and #2 data indicate the packet data transmitted by each terminal in response to the above polling signal. Cm), [:n]・
The numbers . . . are the order numbers of the packets. Also, here terminal 1. Although the case in which terminals 2 are polled alternately is shown, this is not necessarily necessary, and terminal 1 may be polled continuously and terminal 2 may be polled after packet transmission is completed.

In FIG. 3, polling is first applied to terminal 1, and #1 data Cm) is transmitted from terminal 1. Next, terminal 2 is polled and #2 data [
n] is transmitted from terminal 2.

Furthermore, the m+1th poll is performed on terminal 1,
#1 data [”m+1:I is transmitted to the base station side.

At this time, assume that the base station cannot receive #1 data [:m+1:I. The polling signal is provided in advance with a packet order number that indicates which packet each terminal should transmit next. Since the base station could not receive the m+1th packet from terminal #1,
Instruct the terminal to send the m+1th angle during the next poll. When the terminal receives the next poll,
By looking at the packet number, it is possible to detect that the previously sent packet did not reach the base station normally (lost or erroneous), and then send the packet again with instructions from the base station.

〔Effect of the invention〕

That is, by adding a few bits (for example, 3 bits for 8 cycles) to the polling signal, a retransmission instruction (instruction of the packet number to be transmitted) can be given to the terminal. If the polling control method configured in this way is used, in the event of an error during data transmission or data reception, a retransmission request (instruction of transmission packet number) can be easily sent to the terminal without going through the complicated procedure of reversing transmission rights. Can be done. Also, from the perspective of - packet reception,
Since data is received in order, there is no need to exchange control packets such as transmission right reversal and retransmission instructions as in the past, allowing efficient data transmission.

[Brief explanation of the drawing]

Fig. 1 is a sequence diagram of the retransmission control method of the present invention, Fig. 2 is a sequence diagram showing an example when an error occurs in received data in the conventional method, and Fig. 3 is a sequence diagram showing an example of when an error occurs in received data in the conventional method. FIG. 4 is a sequence diagram showing an example when reception is not possible. P#I, P#2...Polling signals for terminals 1 and 2, #l data I: 1ml, (2
)...Packet data order from terminal 1, #2
Data C1:], I:2:l...Packet data order from terminal 2, P#1 10N...Retransmission instruction polling signal for terminal 1, P#1 and #2
...Polling signals for terminals 1 and 2, PK(n) and PK(m), respectively
Packet sequence number, # for terminals 1 and 2, respectively
1 data [:m:l, (m+1]...terminal 1
Packet data order from #2 data [n].

Claims (1)

[Claims] In a wireless packet transmission system in which a base station uses polling to communicate with multiple terminals, a bit indicating the packet number to be transmitted is set in the polling signal that calls each terminal and invites it to send, and polling is performed. When there is an error in the data from the terminal or the data has not been received, the same packet number is indicated again in the packet number to be transmitted when polling the terminal next time, so that the terminal receives the instructed packet. A retransmission control method characterized by performing control to retransmit.