KR100278288B1 - Wireless packet retransmission method using multiple response signals in wireless communication system - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a wireless packet retransmission method in a wireless communication system.

2. The technical problem to be solved by the invention

An object of the present invention is to provide a method for retransmitting a wireless packet by determining whether to retransmit the wireless packet using a plurality of response signals.

3. Summary of Solution to Invention

The present invention includes a first step in which a second radio station receives a radio packet and determines whether there is a reception error; A second step of transmitting an acknowledgment signal to the first radio station at different times over a plurality of times if the reception is normal; A third step of transmitting a negative acknowledgment signal to the first radio station at different times in a plurality of times if the reception error is received; A first step of determining, by the first radio station, whether a positive response signal or a negative response signal is received from the second radio station within a predetermined time; A fifth step of completing a transmission operation of a corresponding wireless packet when at least one acknowledgment signal is received within a predetermined time; And a sixth step of retransmitting the corresponding wireless packet if at least one negative response signal is received or no signal is received within a predetermined time.

4. Important uses of the invention

The present invention is used for wireless packet transmission in a wireless communication system.

Description

Wireless packet retransmission method using multiple response signals in wireless communication system

The present invention relates to a method for retransmitting a wireless packet in a wireless communication system, and more particularly, to a method for retransmitting a wireless packet by determining whether to retransmit the wireless packet using a plurality of response signals.

In data communications, a means of recovering from errors occurring in the transmission path is indispensable. In general, a conventional solution to this problem is an error correction method (FEC: Forward Error Correction) for correcting an error at the receiving end by providing redundancy in the data, and retransmission for detecting an error packet and performing retransmission. Automatic Repeat ReQuest (ARQ) and Hybrid ARQ (Hybrid ARQ) combining the above two methods. The conventional selective retransmission method belongs to a retransmission correction method among the above methods, which will be described below with reference to FIG. 1.

1 is an example of a radio packet retransmission method using a conventional selective retransmission method, in which "11" is a reception packet of a radio station B, "12" is a transmission packet of a radio station A, and "13" is a reception packet. Error packet, "14" is an acknowledgment signal / negative response signal (ACK / NACK), "15" is an acknowledgment signal / negative response signal (ACK / NACK) transmission error, "16" is an uplink transmission (wireless station A packet retransmitted by an error in A → radio station B), and “17” denotes a packet retransmitted by an error in a downlink path (radio station B → radio station A).

In Fig. 1, the transmitting side transmits the arriving packets in order, and when the receiving side receives each signal correctly, the receiving side returns an acknowledgment signal (ACK) indicating that the received signal has been received normally. A negative acknowledgment signal NACK is returned. The transmitting side sequentially processes a new packet having a predetermined number (hereinafter referred to as an "outstanding number") between transmitting the packet and receiving the acknowledgment signal / acknowledgement signal (ACK / NACK). Send by In this case, when the acknowledgment signal ACK is received, the transmitting side transmits a new packet again, but when the acknowledgment signal NACK is received, the transmitting side retransmits the corresponding packet (a packet previously sent but an error has occurred). Further, even when the acknowledgment signal / negative acknowledgment signal (ACK / NACK) itself is discarded due to a transmission error, the corresponding packet is retransmitted in the same manner.

In FIG. 1, which shows a retransmission operation of a packet by a conventional selective retransmission method, packets 2 and 6 are wrong in an uplink path, and an acknowledgment signal ACK 4 and an acknowledgment signal ACK 7 in a downlink path. It is wrong. As a result, in addition to the packet 2 and the packet 6, the retransmission is performed also for the packet 4 and the packet 7 which did not receive the acknowledgment signal ACK within a predetermined time.

As described above, in the conventional selective retransmission method, the acknowledgment signal / negative acknowledgment signal (ACK /) in the downlink transmission path (radio station B → radio station A) as well as when the packet is wrong in the uplink transmission path (radio station A → radio station B). Retransmission is performed even when NACK) is wrong. Therefore, even though the transmission of the packet to be transmitted is successful, unnecessary packet retransmission is performed by error or discard of the acknowledgment signal / acknowledgement signal (ACK / NACK), thereby adopting a retransmission correction method (ARQ). There was a problem that the transmission efficiency of the wireless packet communication is reduced.

In order to solve the above problems, the present invention provides a retransmission method for retransmitting a packet according to a response signal (ACK or NACK) from a receiver for a wireless packet transmitted from a transmitter, using a plurality of response signals. The purpose of the present invention is to provide a method for retransmitting a radio packet by determining whether to retransmit the radio packet, thereby improving transmission efficiency by avoiding retransmission of the entire packet due to transmission error of the response signal itself.

1 is an exemplary view of a radio packet retransmission method in case of using a conventional selective retransmission method.

Figure 2 is an exemplary operation of the radio packet retransmission method according to the first embodiment of the present invention.

3 is a control flowchart of a positive response signal / negative response signal (ACK / NACK) of a radio station B according to Embodiment 1 of the present invention;

4 is a flowchart of a packet transmission and retransmission method of radio station A according to Embodiments 1, 2 and 3 of the present invention.

Fig. 5 is a processing flowchart of a positive response signal / negative response signal (ACK / NACK) of radio station A according to Embodiments 1 and 2 of the present invention.

6 is a processing flowchart of a packet transmission management table of radio station A according to Embodiments 1, 2 and 3 of the present invention.

7 is an exemplary diagram of a packet transmission management table according to embodiments 1, 2 and 3 of the present invention.

8 is an exemplary operation diagram for a radio packet retransmission method according to Embodiment 2 of the present invention.

Fig. 9 is a control flowchart of an acknowledgment signal / negative response signal (ACK / NACK) of radio station B according to the second embodiment of the present invention.

10 is an exemplary operation diagram for a radio packet retransmission method according to Embodiment 3 of the present invention.

Fig. 11 is a flowchart of processing of an acknowledgment signal / negative response signal (ACK / NACK) of radio station A according to the third embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

11, 21, 81, 101: Receive packet of radio station B

12, 22, 82, 102: Transmission packet of radio station A

13, 23, 83, 103: reception error packet

14, 24, 84, 104: positive response signal / negative response signal (ACK / NACK)

15, 25, 85, 105: Acknowledgment signal / Negative response signal with transmission error (ACK / NACK)

16, 26, 86, 106: Packets retransmitted due to an error in uplink (radio station A → radio station B)

17: Packet retransmitted due to an error in downlink path (radio station B → radio station A)

In order to achieve the above object, the present invention provides a wireless packet retransmission method applied to a wireless communication system, comprising: a first step of a second wireless station receiving a wireless packet from a first wireless station to determine whether a reception error is detected; A second step of transmitting an acknowledgment signal (ACK) to the first radio station at different times for a plurality of times if the reception of the first step is normal reception; A third step of transmitting a negative acknowledgment signal (NACK) to the first radio station at a different time in a plurality of times if it is a reception error as a result of the determination in the first step; A fourth step of determining, by the first radio station, whether an acknowledgment signal (ACK) or a negative acknowledgment signal (NACK) is received from the second radio station within a predetermined time after transmitting the radio packet to the second radio station; A fifth step of completing a transmission operation of a corresponding wireless packet when at least one acknowledgment signal (ACK) is received within the predetermined time as a result of the determination in the fourth step; And a sixth step of retransmitting the corresponding radio packet to the second radio station if at least one negative acknowledgment signal (NACK) is received or no signal is received within the predetermined time as a result of the determination in the fourth step. It features.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, looking at the present invention as a whole.

According to the present invention, in a system for performing wireless packet communication between station A and station B, when station B receives a packet transmitted from station A, if the reception of the packet is performed without error, it responds to station A. An acknowledgment signal (ACK) is transmitted for each packet as a signal, and when the station A receives the acknowledgment signal (ACK), the radio station A completes the packet transmission operation, but acknowledges the acknowledgment signal (ACK) for the packet within a predetermined time. Radio station A transmits the packet back to the radio station B when the radio station A transmits the packet back to the radio station B. The response signal for the packet is transmitted in different times in multiple times (multiple times), and the station A transmits a single acknowledgment signal (ACK) in the multiple times (multiple times) response signal. A wireless packet retransmission method of completing a packet transmission operation upon receipt.

That is, according to the present invention, even when the acknowledgment signal / negative acknowledgment signal (ACK / NACK) is wrong in the downlink transmission path, even if there is only one acknowledgment signal / negative acknowledgment signal (ACK / NACK) including the same information transmitted separately. Upon reception, the radio station A can confirm the transmission of the transmitted packet, thereby reducing unnecessary packet retransmission due to an error only in the acknowledgment signal / acknowledgment signal (ACK / NACK), thereby greatly improving the transmission efficiency. do.

Example 1

2 is an exemplary operation of the radio packet retransmission method according to the first embodiment of the present invention, where "21" is a reception packet of a radio station B, "22" is a transmission packet of a radio station A, and "23" is a reception error packet. , "24" indicates an acknowledgment signal / negative response signal (ACK / NACK), "25" means an acknowledgment signal / negative response signal (ACK / NACK) which is a transmission error, and "26" indicates an uplink transmission (radio station A → Represents a packet that has been retransmitted by an error at station B).

In Fig. 2 showing the packet retransmission operation in the uplink packet transmission, the acknowledgment signal / negative response signal (ACK / NACK) has two elements, (H: acknowledgment signal / negative response signal for the preceding packet). ACK / NACK), and B: affirmative response signal / negative response signal (ACK / NACK) for the previous packet. "0" indicates that there is no corresponding packet. Fig. 2 shows a positive reception signal / negative response signal (ACK) of (ACK3, ACK4) and (ACK6, ACK7) in the downlink transmission path as shown in the case of Fig. 1 above. / NACK).

In the conventional selective retransmission method (see FIG. 1), retransmission of packet 4 occurred due to ACK4 wrong. However, in the first embodiment of the present invention, even if (ACK3, ACK4) is incorrect, packet 4 is performed by the following (ACK4, ACK5). Since it is possible to confirm the delivery of a packet, unnecessary retransmission of packet 4 is prevented. Also, packet 7 cannot be retransmitted for the same reason, and as a result, only packets 2 and 6 in which an error occurs in the uplink path are retransmitted.

In the first embodiment of the present invention, the acknowledgment signal / acknowledgment signal (ACK / NACK) for one packet is transmitted two times in succession, but the optimal number of transmission times and the timing of transmission are determined according to the conditions of the transmission path. Can be set in various ways (see Examples 2 and 3 described below).

3 is a control flowchart of the acknowledgment signal / negative response signal (ACK / NACK) of the radio station B according to the first embodiment of the present invention.

First, when receiving a packet transmitted to the own station (302), the radio station B performs an error search by a cyclic redundancy check (CRC) or the like (303). If it is received without error, write 'ACKn' in variable B (304). Where n is the packet number written in the received packet. On the other hand, when an error is detected, the packet number can be identified in advance due to a known packet number transmitted by reservation or the like, or when the packet number is written in a header coded by another cyclic redundancy check (CRC). 'NACKn' is written into variable B (307), but if identification is not possible, "0" is written (306).

Next, variable B and H, which are the positive response signal / negative response signal (ACK / NACK) for the packet received at the previous timing, are collected to generate an MS (Mobile Sequence) (308). Transmit (309). After the transmission, the value of the new variable B is substituted into the variable H, and the process returns to the packet reception process 302 and the same process is repeated.

On the other hand, when no new packet is received, it is determined whether the variable H is "0" (311). If it is "0", it is in a waiting state (301). If it is not "0", 0 is written into the variable B (312). After the MS has been sent 309 with the H of the previously received packet 308, the process returns to the packet receiving process 302.

4 is a flowchart of a packet transmission and retransmission method of radio station A according to Embodiments 1, 2, and 3 of the present invention.

The radio station A receives the acknowledgment signal / negative acknowledgment signal (ACK / NACK) from the radio station B with respect to the transmission completion packet (402), and the acknowledgment signal (ACK) does not return within a certain time for the transmission completion packet. Whether there is a packet (timeout packet) 404, whether there is a packet waiting to be retransmitted by receiving a negative acknowledgment signal (NACK) 405, whether there is a new packet to be transmitted 406, and whether the packet transmission management table is updated. Continuous monitoring and control of status of 5 items.

First, when an acknowledgment signal / negative acknowledgment signal (ACK / NACK) is received in the standby state (401), an acknowledgment signal / negative acknowledgment signal (ACK / NACK) process 403 to be described below is executed. When there is a TimeOut packet or when there is a NACK packet, retransmission 407 and 408 of the packet is performed, respectively. If a new transmission packet is generated, it is determined whether or not transmission is possible (409), and if possible, the packet is transmitted (410). In this case 409, transmission is not possible when, for example, the packet number sequentially assigned to the newly transmitted packet becomes the same as the number of the oldest packet among the packets not receiving the acknowledgment signal (ACK). This is because a packet number assigned to a packet generally repeats a range of numbers (for example, 0 to 8), so that a packet having the same packet number is transmitted to a packet that has not received an acknowledgment signal (or a negative response signal). In this case, it is impossible to determine which packet is the acknowledgment signal / negative response signal (ACK / NACK) indicating the same packet number.

After various processing, the packet transmission management table is always updated (411). Here, the packet transmission management table has the configuration as shown in Fig. 7, and stores the packet number, the elapsed time since transmission (in this embodiment, in msec) and the state of each packet as information. In the state of the packet,

(1) Waiting: After the packet is transmitted, the acknowledgment / non-acknowledgement signal (ACK / NACK) for the packet is not received.

(2) Negative response signal (NACK): a state in which a negative response signal (NACK) for the packet is received,

(3) Timeout: There is a state in which the waiting state exceeds a predetermined prescribed time (in this embodiment, 6 msec).

In the update process 411 of the packet transmission management table, the elapsed time of all the waiting packets on this packet transmission management table is updated, and the following operation is performed in some cases.

(a) When the Timeout / NACK packet is retransmitted:

The information of the retransmitted Timeout / Negative Response Signal (NACK) packet is deleted from the packet transmission management table, and a new retransmission packet is written to the packet transmission management table.

(b) When a new packet is sent:

Write information about a new packet into the packet transmission management table.

5 is a flowchart of processing of an acknowledgment signal / negative response signal (ACK / NACK) of radio station A according to Embodiments 1 and 2 of the present invention.

First, the radio station A, which has normally received an acknowledgment signal / negative response signal (ACK / NACK) (501), first decodes the variable H (502). Thereafter, with reference to the packet number (503), if the acknowledgment signal / negative response signal (ACK / NACK) for the packet which has already been processed (packet not stored in the packet transmission management table), nothing is done. In this case, a table processing process 504 to be described later is performed. Next, variable B is decoded (505), and the table processing is similarly performed (506). When the processing is completed, the flow returns to the flow of FIG.

6 is a process flowchart of a packet transmission management table of radio station A according to Embodiments 1, 2 and 3 of the present invention.

First, when the decrypted positive response signal / negative response signal (ACK / NACK) is the positive response signal (ACK) (601), the corresponding packet is deleted from the packet transmission management table (602), and the negative response signal (NACK) is In the case (601), the state in the packet transmission management table is recorded as a negative response signal (NACK) (603). Thereafter, the flow returns to the flow of FIG. 5.

Example 2

When the wireless transmission path is under slow fading, the probability of successive signal errors is increased. In this case, it is more effective to transmit the same acknowledgment signal / negative acknowledgment signal (ACK / NACK) at intervals rather than continuously transmitting them as in the first embodiment. Therefore, in the second embodiment of the present invention, in consideration of this, the acknowledgment signal / negative response signal (ACK / NACK) is regarded as (H: acknowledgment signal / negative response signal (ACK / NACK) for two previous packets, and B: immediately before. It is configured in a format called an acknowledgment signal / negative response signal (ACK / NACK) for the packet.

8 is an exemplary operation diagram of a radio packet retransmission method according to the second embodiment of the present invention, in which "81" is a reception packet of a radio station B, "82" is a transmission packet of a radio station A, and "83" is a reception error. Packet, "84" is an acknowledgment signal / negative response signal (ACK / NACK), "85" is an acknowledgment signal / negative response signal (ACK / NACK) is a transmission error, "86" is an uplink transmission (radio station A → indicates packets retransmitted by an error at station B).

In the second embodiment of the present invention, two positive acknowledgment signals / negative acknowledgment signals (ACK / NACK) of (NACK2, ACK4) and (ACK3, ACK5) are wrong in succession, but the positive acknowledgment signal (ACK) for packet 4 is Since it is transmitted with the following acknowledgment signal / negative response signal (ACK / NACK) of (ACK4, NACK6), unnecessary retransmission is prevented. For the same reason, packet 5 is also prevented from retransmitting.

9 is a control flowchart of an acknowledgment signal / negative response signal (ACK / NACK) of the radio station B according to the second embodiment of the present invention.

According to the second embodiment of the present invention, in response to the variable B 'and the variable H, the variable H' (the positive response signal / negative response signal (ACK / NACK) for the previous packet) is used (901, 910, 913). Transmission of the negative acknowledgment signal (ACK / NACK) is delayed by one packet. In addition, about another control flow, it is the same as that of Example 1 (FIGS. 4-7).

Example 3

When the error rate of the wireless transmission path is very high, the frequency efficiency may increase as the number of transmissions of the acknowledgment signal / negative response signal (ACK / NACK) is increased. In the third embodiment of the present invention, an example of the case where the acknowledgment signal / negative response signal (ACK / NACK) is transmitted three times in succession is shown.

FIG. 10 is an exemplary operation diagram of a method for retransmitting a radio packet according to Embodiment 3 of the present invention, in which "101" is a reception packet of a radio station B, "102" is a transmission packet of a radio station A, and "103" is a reception error. Packet, "104" indicates an acknowledgment signal / negative response signal (ACK / NACK), "105" indicates an acknowledgment signal / negative response signal (ACK / NACK) which is a transmission error, and "106" indicates an uplink transmission path (radio station A → indicates packets retransmitted by an error at station B).

In Embodiment 3 of the present invention, the acknowledgment signal / negative response signal (ACK / NACK) of (NACK2, ACK1, ACK3) and (ACK4, ACK3, ACK5) is wrong. In this case, retransmission of packet 3 occurs in the method of transmitting an acknowledgment signal / negative response signal (ACK / NACK) every other as in the second embodiment, but in the third embodiment, an acknowledgment signal / negative response between the two occurs. Since the signal ACK / NACK includes the acknowledgment signal / negative response signal ACK / NACK for packet 3, retransmission of packet 3 is prevented. Transmission control of the positive response signal / negative response signal (ACK / NACK) of the third embodiment only changes MS = (H, B) to MS = (H ', H, B) in 908 of FIG. Is enough. However, the processing flow of the acknowledgment signal / negative response signal (ACK / NACK) is added to the flow for the decoding of H ', as shown in Figure 11 (116 to 118). Other flows are the same as those in Embodiments 1 and 2 (Figs. 4, 6 and 7).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

In the present invention as described above, the radio station B transmits a response signal for the same packet at different times over a plurality of times (multiple times), and the radio station A has one of a plurality of positive response signals (ACK). Even if the packet is received, the transmission operation of the packet is completed, thereby reducing unnecessary packet retransmission of the uplink path caused by an error or discarding an ACK / NACK signal on the downlink path. As a result, the transmission efficiency can be improved.

On the other hand, since the response signal is transmitted a plurality of times, the signal amount of the response signal increases in the downlink transmission path. For this reason, the effect of improving the frequency efficiency is larger as the packet length is larger than the signal length of the response signal and as the error rate of the transmission path is high, such as wireless.

In general, in a wireless packet communication consisting of a central station and a plurality of terminal stations, the transmission path from the central station to the terminal station is sequential transmission, but since the random access is performed from the terminal station to the central station, the latter transmission path is more likely to collide than the former. Because of the efficiency reduction caused by the present invention, when the present invention is used for packet transmission from the terminal station to the centralized station, it is possible to increase the efficiency of the uplink transmission path by increasing the signal amount of the response signal of the downlink transmission path having a margin.

Claims (10)

In the wireless packet retransmission method applied to a wireless communication system, A first step in which the second radio station receives a radio packet from the first radio station and determines whether a reception error occurs; A second step of transmitting an acknowledgment signal (ACK) to the first radio station at different times for a plurality of times if the reception of the first step is normal reception; A third step of transmitting a negative acknowledgment signal (NACK) to the first radio station at a different time in a plurality of times if it is a reception error as a result of the determination in the first step; A fourth step of determining, by the first radio station, whether an acknowledgment signal (ACK) or a negative acknowledgment signal (NACK) is received from the second radio station within a predetermined time after transmitting the radio packet to the second radio station; A fifth step of completing a transmission operation of a corresponding wireless packet when at least one acknowledgment signal (ACK) is received within the predetermined time as a result of the determination in the fourth step; And A sixth step of retransmitting the corresponding radio packet to the second radio station if at least one negative response signal NACK is received or no signal is received within the predetermined time as a result of the determination in the fourth step; Wireless packet retransmission method comprising a. The method of claim 1, A seventh step of processing the radio packet in the fifth step or the sixth step and recording the result in a packet transmission management table; Wireless packet retransmission method further comprising a. The method of claim 2, The packet transmission management table, And a packet number field, an elapsed time field after transmission, and a status field of each packet. The method of claim 3, wherein The packet state of the status field is A waiting state indicating an acknowledgment / non-acknowledgement (ACK / NACK) non-receipt state for the packet after transmission of the packet; A negative acknowledgment signal (NACK) state indicating a state of receiving a negative acknowledgment signal (NACK) for the packet; And A wireless packet retransmission method, characterized in that the waiting state is any one of a timeout state indicating a state exceeding a predetermined prescribed time. The method of claim 2, The recording process of the seventh step, When the Timeout / Negative Response Signal (NACK) packet is retransmitted, the information of the retransmitted Timeout / Negative Response Signal (NACK) packet is deleted from the packet transmission management table, and a new retransmission packet is deleted. Recording in the packet transmission management table, and in the case where a new packet is transmitted, information about the new packet is recorded in the packet transmission management table. The method according to any one of claims 1 to 5, In the second and third steps, the process of transmitting the response signal at different times over a plurality of times, A method for retransmitting a wireless packet, comprising: a response signal for a preceding packet and a response signal for a previous packet are bundled and transmitted at different times over two times. The method according to any one of claims 1 to 5, In the second and third steps, the process of transmitting the response signal at different times over a plurality of times, A method for retransmitting a radio packet, comprising: a response signal for a predetermined number of packets and a response signal for a previous packet are bundled and transmitted at different times over a predetermined number of times. The method of claim 7, wherein The sending process is A method for retransmitting a radio packet, comprising: a response signal for two packets and a response signal for a previous packet are bundled and transmitted at different times in two times. The method of claim 7, wherein The sending process is A method for retransmitting a radio packet, comprising: a response signal for three packets, a response signal for two packets, and a response signal for a previous packet are bundled and transmitted three times at different times. In a wireless communication system having a processor, A first function of the second radio station receiving a radio packet from the first radio station and determining whether there is a reception error; A second function of transmitting an acknowledgment signal (ACK) to the first radio station at different times over a plurality of times when the determination in the first function is normal reception; A third function of transmitting a negative acknowledgment signal (NACK) to the first radio station at different times over a plurality of times if it is a reception error as a result of the determination in the first function; A fourth function of determining whether an acknowledgment signal (ACK) or a negative acknowledgment signal (NACK) is received from the first radio station within a predetermined time after the first radio station transmits the radio packet to the second radio station; A fifth function of completing a transmission operation of a corresponding wireless packet when at least one acknowledgment signal (ACK) is received within the predetermined time as a result of the determination in the fourth function; And A sixth function of retransmitting the corresponding radio packet to the second radio station if at least one negative response signal NACK is received or no signal is received within the predetermined time as a result of the determination in the fourth function; A computer-readable recording medium having recorded thereon a program for realizing this.