JPH1146217A - Radio packet re-transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an identical packet from being transmitted for a plurality of number of times by aborting wasteful packets at a subordinate layer and not transmitting them, while detecting re-transmission data packets at a host layer or taking a re-transmission timer of the host layer into account. SOLUTION: A data packet A3-8 of TCP/IP3-3 is divided into a plurality of radio packets on an LLC layer 3-4 and sent for a radio block 3-5, which are then received by a logical link control LLC 3-6 of a radio station #2 and handed over to the TCP/IP layer 3-7. In the case of transferring a data packet B3-12, a transferred packet B-3 among radio packets divided on the LLC layer 3-4 has become re-transmitted due to an error. After re-transmission is repeated twice, a TCP/IP3-3 re-transmission timer expires, and the packet 3-15 is resent. At this time, the radio packets resent on the LLC layer are aborted and the radio packet 3-16 is sent again. Then the packet is received and assembled by the LLC3-6 of the radio station #2 and is handed over to the TCP/IP3-7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless data communication, and more particularly to a wireless packet retransmission method characterized by a wireless packet retransmission protocol in wireless data communication.

[0002]

2. Description of the Related Art When performing wireless data communication, the reliability of a transmission path is lower than that of a wire. For this reason, for example, TCP / I
P (Transmission Control Protocol / Internet Protoco
When a protocol developed for a wired network as in l) is applied to a wireless transmission path as it is, there is a problem that transfer efficiency is extremely deteriorated. In order to improve this, it is common to install a transmission protocol in consideration of the characteristics of the wireless transmission path below these existing protocols. For example, in wireless packets, US CDPD (Cellular Digital P
acket Data) is MDLP in the lower layer of TCP / IP
(Mobile Data Link Protocol) is set as a radio link control protocol. In data communication by circuit switching, for example, PHS (Personal Handyphone Syst
em) data communication with PIAFS (PHS Internet Access)
Forum Standard), a protocol that guarantees errors in wireless sections. In these systems, a data packet is divided into shorter retransmission units, and a transmission error of a packet in a wireless section is compensated by a unique retransmission system.

On the other hand, TCP also has a retransmission procedure to guarantee normal end-to-end data transfer. Specifically, this method is a method of transmitting a packet while recognizing an acknowledgment signal from a transmission destination for transmitted data, and retransmitting the packet if the acknowledgment signal does not return even after waiting for a predetermined time. Here, in the Internet environment that is the target of TCP, the time until the delivery confirmation signal returns varies according to the fluctuation of the traffic on the route. Therefore, in TCP, the value of the retransmission timer is increased or decreased accordingly. .

As described above, a system for performing wireless data communication generally adopts a two-layer structure of a retransmission protocol corresponding to an existing wired network and an application and a retransmission protocol corresponding to a wireless transmission path.

By the way, HIPERLAN (HIgh PErfoma)
nce Radio Local Area Network) has a function of setting a remaining lifetime for each wireless packet in this lower layer, and discarding a packet having a remaining time of 0 during transfer in a wireless section. This is because a node that relays a wireless packet transfers a new remaining lifetime as a new remaining lifetime to the next node by subtracting the time until the packet is forwarded from the remaining lifetime attached to the wireless packet at the time of reception. Is achieved. This prevents wireless packets from being transferred in lower layers for longer than necessary.

[0006]

When the retransmission protocol has a two-layer structure as in the prior art, the upper retransmission timer expires while retransmitting the wireless packet,
It is assumed that the same data packet as the currently retransmitted packet is transferred to the lower layer. In this case, the same packet is transmitted twice in an actual wireless section, which is inefficient from the viewpoint of wireless resources. FIG. 17 shows a case where the radio station # 1 (15-1) transmits the
An example of packet transfer to 2) is shown. Here, as shown in FIG. 1, the system configuration includes a pair of radio stations (1-1) and (1-
2), as shown in FIG. 2, having an upper data packet retransmission protocol TCP (2-5) and a lower radio packet retransmission protocol LLC (Logical Link Control) (2-4). The data packet A (15-8) of the TCP / IP (15-3) is divided into a plurality of radio packets A-1, A-2, A-3 (15-9) by the LLC layer (15-4). Then, it is transmitted in the wireless section, and is received and assembled by the LLC (15-6) of the wireless station # 2 (15-10), and then the TCP layer of the wireless station # 2 (15-7)
(15-11). By the way, data packet B
When transferring (15-12), of the wireless packets B-1, B-2, and B-3 (15-13) generated by dividing this by LLC, B-3
Was retransmitted due to an error (15-14). On the other hand, also in the TCP / IP (15-3) of the wireless station # 1, the data packet B is retransmitted (15-15). As a result, the last B-3 wireless packet is transmitted unnecessarily, and wireless resources are wasted.
-16,15-17,15-18).

In order to prevent such a phenomenon, for example, there is a method of setting a survival time for each wireless packet as in HIPERLAN described in the prior art. However, in this method, resetting of the remaining survival time in the intermediate transfer node is required. Because it is necessary, there is a problem that cannot be applied when passing through a general router that does not have such a function.

Therefore, according to the present invention, the same packet is prevented from being transferred a plurality of times by retransmission when the retransmission protocol has a two-layer structure without giving a special function to the intermediate node on the way. The purpose is to prevent resources from being wasted.

[0009]

According to the present invention, in order to achieve the above-mentioned object, a case where a data packet has passed from the arrival at a lower layer, a retransmission timer value of an upper layer, or a data packet has passed through a general network is used. Is characterized by defining a time until a wireless packet is discarded in a lower layer using an estimated transfer delay time (claims 1, 2, and 3). That is, if a data packet is likely to be retransmitted due to expiration of the retransmission timer of the upper layer while retransmitting the radio packet in the lower layer due to a transmission error or the like, the previous radio packet in the retransmission state in the lower layer is discarded. The point is that CDPD and PIAFS that independently performed retransmission processing irrespective of the upper retransmission timer
And so on. Also, the time from transmission of the data packet in the upper layer to reception of the acknowledgment signal (that is, the required round-trip time when passing through the wireless section and the network section), and the fact that the wireless packet has been delivered to the wireless base station. Estimate the transfer delay time in the network section based on the time required to check (the one-way time required to transfer the wireless section) and determine the delay time that can be tolerated for retransmission in the wireless section (hereafter, the allowable retransmission delay time). )
This is different from HIPERLAN in which the via node resets the lifetime for each wireless packet.

Further, according to the present invention, if the information of the data packet can be referred to also in the lower layer, it is recognized that the data packet has been retransmitted, and if the radio packet generated from this has already been transmitted in the lower layer, There is a feature that the corresponding wireless packet is discarded so as not to be transmitted to the wireless section (claim 4). This prevents useless use of resources. A similar effect can be obtained by ignoring the retransmitted data packet itself while continuing the retransmission of the lower layer (claim 5).

If the relationship between the number of retransmissions and the delay time can be estimated, the upper limit of the number of retransmissions in the lower layer is determined from the allowable retransmission delay time (claim 6), so that the timer is not used. An effect equivalent to each of the above methods can be obtained.

By the way, in order to recognize retransmission of a data packet in the lower layer, it is necessary to look at the information of the upper layer in the lower layer. At this time, storing and comparing the entire packet is inefficient from the viewpoint of buffer capacity and processing load. Therefore, in the present invention, an information block is generated based on a certain method from a part or the whole of a data packet, and an information block of the data packet transferred in the lower layer and a data packet of the data packet transferred from the upper layer are generated. If the information blocks match, it is recognized that the data packet has been retransmitted (claim 7). Thereby, it is possible to efficiently recognize the retransmission of the data packet.

According to the present invention, it is possible to prevent the same packet from being transmitted a plurality of times due to retransmission in a wireless section without adding a special function to a transit node on the way, thereby preventing useless use of wireless resources. The effect is obtained.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. Note that the first embodiment is the first embodiment.
The second embodiment is described in claims 2 and 3, the third embodiment is described in claims 4 and 7, the fourth embodiment is described in claims 5 and 7, and the fifth embodiment is described in claims 5 and 7. The present invention corresponds to the sixth aspect of the invention. In addition,
In the third and fourth embodiments, an error detection code given to each data packet is used as a method of recognizing retransmission of a data packet. The error detection code is stored until the transmission of each data packet is completed, and each time a data packet is transferred from the upper layer, the assigned error detection code is compared with the stored detection code. If they match, it is recognized as a retransmission packet.

[Embodiment 1] Embodiment 1 based on the present invention
FIG. 1 shows an example of the system configuration of FIG. As shown here, the system consists of a pair of radio stations # 1, # 2 (1-1) and (1-2),
It is assumed that wireless data communication is performed between wireless stations. FIG. 2 shows the protocol configuration. Here, TCP / IP (2-5) is used as a data packet retransmission protocol, and LLC (Logical Link Control) is used as a wireless packet retransmission protocol.
(2-4) is defined. AP (2-6) indicates an application layer, and PHY (2-3) indicates a physical layer. FIG. 3 shows that the wireless stations # 1 (1-1) to # 2 (1-
An example of packet transfer to 2) is shown. TCP / IP (3
-3) Data packet A (3-8) is LLC layer (3-4)
Is divided into a plurality of wireless packets A-1, A-2, and A-3 (3-9), and is transmitted in the wireless section (3-5).
After receiving and assembling at C (3-6) (3-10), radio station # 2
(3-11) to the TCP layer (3-7). Next, when transferring the data packet B (3-12), the wireless packets B-1, B-2, B-3 (3-1
In 3), the transfer of the wireless packet B-3 was retransmitted due to an error (3-14). Here, after this retransmission is repeated twice, the TCP / IP (3-3) retransmission timer expires, and the data packet B (3-15) is retransmitted. At this time, L
The B-3 wireless packet retransmitted in the LC layer is discarded, and the B-1 to B-3 wireless packets (3-16) are transmitted again. That is, useless transmission of the B-3 packet as shown in FIG. 17 is prevented. And wireless packets
After B-1 to B-3 are received and assembled by the LLC (3-6) of the wireless station # 2 (3-17), the TCP layer of the wireless station # 2 (3-7)
(3-18).

FIGS. 4 and 5 show the transmission flow of the radio station at this time. FIG. 4 shows a case in which a wireless packet is discarded in response to a timer, and FIG. 5 shows a case in which discarding is performed in response to retransmission of an upper layer. Either one may be applied. By the way, in the TCP protocol, the delay time required for data packet transfer is calculated by measuring the time from the transmission of data to the reception of an acknowledgment signal and performing weighted averaging, and retransmission is performed using a method defined in the TCP standard. Determines the timer value ([References] Douglas Come
r, Network construction by TCP / IP vol.1, Kyoritsu Publishing, 1994. ). When using the former method, LLC uses TC
When a data packet is received from the P / IP layer (4-
2) Read the value of the TCP retransmission timer (4-3). Next, after the timer is started (4-4), a wireless packet is generated (4-5), and transmission to the wireless section is performed (4-7). At this time, if the timer times out due to a transmission error (4-
6) Among the wireless packets generated from the data packet, all the untransmitted wireless packets stored in the buffer at this time are discarded (4-9), and the retransmission operation is stopped. After the transmission of all these wireless packets is completed (4-8), the state returns to the standby state.

On the other hand, when the latter method is used, a timer is not used, and when a data packet is received from the TCP / IP layer (4-11), a wireless packet is generated (4-1).
2) If the data packet is transmitted to the wireless section (4-13) and the data packet is retransmitted from the upper layer before the wireless packet transfer is completed (4-14) (4-15), the previous data packet B
Wireless packets B-1, B-2, B-3 (3-3) generated from (3-12)
-13) is discarded (4-16).

[Embodiment 2] Embodiment 2 based on the present invention
FIG. 6 shows an example of the system configuration of FIG. As shown here, the system consists of a wireless terminal (hereinafter # 1) (5-1), a wireless base station (hereinafter # 2) (5-2), a network to which the wireless base station is connected (5-3), and the same network. , And performs data communication between the wireless terminal and the wired terminal via the wireless base station and the network. FIG. 7 shows the protocol configuration. Here, TCP / IP (6-6) which is a data packet retransmission protocol is # 1
It is terminated between (5-1) and # 3 (5-3). On the other hand, LLC (6-5) which is a wireless packet retransmission protocol is # 1.
It is terminated between (5-1) and # 2 (5-2). Also, A
P (6-7) is the application layer, PHY (6-4)
Indicates a physical layer, and DL (6-8) indicates a data link between # 2 and # 3.

FIG. 8 shows an operation example when a packet is transferred from # 1 (5-1) to # 3 (5-3) via # 2 (5-2). Similarly to the first embodiment, the data packet A (7-12) of the TCP / IP (7-4) has a plurality of wireless packets A-1, A-2, A-3 (7-) in the LLC layer (7-5). After being divided into 13)
Transmitted in the wireless section (7-6), received by the # 2 LLC (7-7) and received (7-14)
It is forwarded to (7-8) (7-15). In the DL, the data packet A is transmitted to the network (7-9), and the DL of # 3 (7-1) is transmitted.
In (0), the received data packet (7-16) is
Hand over to P / IP (7-11) (7-17). At this time, TC of # 1
# 3 TCP / P / P after P / IP starts data transmission
The time it takes for the IP to receive it is the total delay D1 (7-2
5) is defined. In the TCP layer, D1 is always calculated and updated using the time from when data is transmitted to when an acknowledgment signal is received. On the other hand, the radio delay D2 (7-26) can be measured also in the LLC layer by using the acknowledgment signal. Using these, the time D required for packet transfer in the network (= D2−D1) can be obtained. This is defined as intra-network delay.

In this figure, when transferring the data packet B (7-18), of the radio packets B-1, B-2, B-3 (7-19) generated by dividing the data packet by the LLC, The transmission of B-3 was retransmitted due to an error (7-20). Here, after the retransmission is repeated once, the time exceeds the value obtained by subtracting twice the network delay (D × 2) from the value of the retransmission timer for retransmission in the upper TCP / IP (7-4). 3 has been discarded. This is because even if a packet is transmitted beyond this time, there is a high probability that the retransmission timer expires before the upper layer receives the acknowledgment.
This has the effect of preventing transmission. In the TCP / IP (7-4), after the timer expires, the data packet B is retransmitted (7-21), and through the same procedure as the data packet A, the TCP / IP of # 3 is performed.
(7-11) (7-22, 7-23, 7-24, ...).

FIG. 9 shows a transmission flow of the wireless terminal / wireless base station according to the second embodiment. As described above, in the TCP protocol, the total delay D1 is always monitored, and the retransmission timer value is determined. After receiving the data packet from the upper layer (8-2), the LLC calculates the allowable retransmission delay time (8-3) obtained by subtracting twice the above-mentioned intra-network delay (2D) from the retransmission timer value. . Next, after the timer is started (8-4), a wireless packet is generated (8-5) and the wireless packet is transmitted (8-7). Here, if the above-mentioned timer expires due to retransmission before the data packet transmission is completed (8-8) (8-6), the wireless packet generated by dividing the data packet being transmitted is Then, the wireless packets that have not been transmitted and remain in the buffer are discarded (8-9).

In the case of packet transfer from # 3 to # 1, # 2 does not have an intra-network delay and a TCP retransmission timer, so that an allowable retransmission delay time cannot be calculated. Thus, in the second embodiment, this problem is solved by notifying the wireless base station of the allowable retransmission delay time from the wireless terminal station. FIG. 10 shows a flow for notifying an allowable retransmission delay time from a wireless terminal station to a wireless base station. Timer 1 is a period for notifying the wireless base station of the allowable retransmission delay time. After the timer 1 is started in the wireless terminal station (9-13), when the timer 1 times out (9-
3) Read the TCP retransmission timer value (9-10) and notify the radio base station of the permissible retransmission delay time (9-11) calculated from the read TCP retransmission timer value and network delay D (9-).
12). By the way, in order to obtain the intra-network delay D, the wireless terminal station starts the timer 2 when transmitting a data packet (9-4), except for a retransmission packet (9-5).
Here, the value of the timer 2 is the same as the value of the TCP retransmission timer. Only when an acknowledgment signal is received from the partner station until the timer 2 times out (9-9) (until the packet is retransmitted) (9-7), half of the elapsed time of the timer 2 is set as the intra-network delay D Remember (9-8). The base station notified of the allowable retransmission delay time by this operation transmits and discards the wireless packet in the same flow as in FIG.

In this embodiment, the network (5-3)
Is a wired network, but 5-4 is a wireless terminal and 6-8 is L
By replacing with LC, it is also possible to support a wireless network.

[Embodiment 3] Embodiment 3 based on the present invention
FIG. 11 shows an example of the operation of FIG. Here, the system configuration and the protocol configuration were the same as in the first embodiment. The difference from FIG. 3 is that the data packet B retransmitted in the TCP / IP layer
Wireless packet (10-16) generated by dividing (10-15)
When transmitting a packet, the wireless packet B-
1 and B-2 are not transmitted, but only the wireless packet B-3 is transmitted. LLC of wireless station # 2 (10-6)
Then, the already received wireless packets B-1, B-2 (10-14)
And the retransmission wireless packet B-3 (10-17) in combination to synthesize a data packet B (10-18) and deliver it to the TCP / IP layer (10-7). Note that in FIG.
10-1 and 10-2 correspond to reference numerals 1-1 and 1-2 in FIGS.
-3 to 10-18 correspond to the reference numerals 3-1 to 3-18 in FIG.

FIG. 12 shows a radio station transmission flow of this embodiment. Here, the timer is not used, and it is detected that the data packet has been retransmitted from the upper layer, and the unretransmitted wireless packet is discarded (11-7). Also, after generating a wireless packet from a retransmitted data packet (11-8), already transmitted wireless packets are discarded (11-9), and only untransmitted wireless packets are transmitted. FIG.
And FIG. The processing 11-2, 11 in FIG.
At -3, 11-5, and 11-6, the same processes as the processes 4-11, 4-12, 4-13, and 4-15 of FIG. 4 are performed, respectively.

[Embodiment 4] Embodiment 4 based on the present invention
13 is shown in FIG. Here, the system configuration and the protocol configuration are the same as in the second embodiment. The difference from FIG. 10 is that the data packet B in the TCP / IP layer (12-4)
When (12-24) is retransmitted, the lower LLC layer (12-
The point 5) is that the retransmitted data packet is discarded without being divided into wireless packets and the wireless packet is not discarded in the middle. In this case, the radio packet B-3 is retransmitted three times at the LLC (12-5), received at the LLC (12-7) at the third retransmission, and then received at the DL (12-8). The data packet B is combined with the wireless packets B-1 and B-2 that have been combined (12
-twenty one). Then, the combined data packet B is delivered to the TCP / IP layer (12-11) via the DL layer (12-10) via the network section (12-9). In FIG. 13, reference numerals 12-1, 12-2, and 12-3 are shown in FIGS.
Reference numerals 5-1 5-2 and 5-4 correspond to reference numerals 12-4 to 12-20, and reference numerals 7-4 to 7-20 in FIG.

FIG. 14 shows a transmission flow of the radio terminal / radio base station in the fourth embodiment, and FIG.
4 shows a management flow of an RC (error detection code) unit storage memory. In this embodiment, an error detection code assigned to all data packets is used to determine a retransmission packet. The LLC layer (12-5) that has received the data packet from the upper layer (13-2) checks whether or not the CRC part of the packet is already stored in the memory (13-).
3) If not stored, it is determined that the packet is not a retransmission packet, and a wireless packet is generated (13-4).
Send to 6) (13-5). On the other hand, if the CRC part matches the one stored in the memory, it is regarded as a retransmission packet and the data packet is discarded (13-7). Transmission of the radio packet continues (13-6) until it is completed. The difference from the second embodiment is that the wireless packet is not discarded during transmission. LLC (12-
In 5), when a data packet from the upper layer is received (13-9), only the CRC part of the data packet is extracted (13-10) and stored in the memory (13-11), and the data packet is transmitted. If completed (13-12), after a predetermined period of time, the stored CRC part of this data packet is deleted (13-13).

[Embodiment 5] Embodiment 5 based on the present invention
FIG. 16 shows a transmission flow of the wireless terminal / wireless base station.
Here, the system configuration and the protocol configuration are the same as in the first embodiment. An operation example is the same as that in FIG. 3 when the upper limit of the number of retransmissions is two. The LLC layer (3-4) that has received the data packet from the upper layer (14-2) sets the upper limit of the number of retransmissions of the wireless packet (14-3) based on the TCP retransmission timer value (14-4). This is because when the number of retransmissions is n and the time required for transmission in the radio section is t (n), the condition that this does not exceed the TCP retransmission timer value T (t (n)
<T) can be determined from the maximum value of n that satisfies <T). Thereafter, a wireless packet is generated (14-5) and transmitted (14).
-7). If the number of retransmissions before the transmission is completed (14-8) exceeds the preset upper limit (14-6), the wireless packet in the buffer is discarded (14-9). As described above, L
The difference from the first embodiment is that the retransmission discarding of the LC is defined by the number of retransmissions without using a timer.

[0029]

According to the wireless packet retransmission protocol of the present invention, when a retransmission protocol dedicated to wireless communication is set in a lower layer of a retransmission protocol generally used in a wired network, detection of retransmission data packets in an upper layer,
Alternatively, in consideration of the retransmission timer value of the upper layer, the lower layer discards useless packets and does not perform transmission. As a result, it is possible to prevent the same packet from being transmitted a plurality of times due to retransmission in a wireless section without giving a special function to a transit node on the way, and to obtain an effect of preventing useless use of wireless resources. . Further, by using the information block generated from the data packet, it is possible to efficiently detect the retransmission of the data packet of the upper layer in the lower layer.

[Brief description of the drawings]

FIG. 1 shows a system configuration example according to first and second embodiments of the present invention.

FIG. 2 shows a protocol configuration example according to the first and second embodiments of the present invention.

FIG. 3 shows an example of a packet transfer operation from a wireless station # 1 to a wireless station # 2 according to the first embodiment of the present invention.

FIG. 4 shows a transmission flow (discard by a timer) of a wireless station according to the first embodiment of the present invention.

FIG. 5 shows a transmission flow (discard due to retransmission data packet) of the wireless station according to the first embodiment of the present invention.

FIG. 6 shows a system configuration example according to the second and fourth embodiments of the present invention.

FIG. 7 shows a protocol configuration example according to the second and fourth embodiments of the present invention.

FIG. 8 shows an example of a packet transfer operation from # 1 to # 3 in Embodiment 2 of the present invention.

FIG. 9 shows a transmission flow of a wireless terminal / wireless base station according to Embodiment 2 of the present invention.

FIG. 10 shows a flow of notification of an allowable retransmission delay time of a wireless terminal to a wireless base station according to the second embodiment of the present invention.

FIG. 11 is a diagram showing an example of operations from # 1 to # 2 according to the third embodiment of the present invention.
An example of a packet transfer operation to the host is shown.

FIG. 12 shows a transmission flow of a wireless station according to Embodiment 3 of the present invention.

FIG. 13 is a diagram illustrating a configuration example of the fourth embodiment of the present invention.
An example of a packet transfer operation to the host is shown.

FIG. 14 shows a transmission flow of a wireless terminal / wireless base station according to Embodiment 4 of the present invention.

FIG. 15 shows a management flow of a CRC section storage memory of a wireless terminal / wireless base station in Embodiment 4 of the present invention.

FIG. 16 shows a transmission flow of a wireless station according to Embodiment 5 of the present invention.

FIG. 17 shows an example of a packet transfer operation from # 1 to # 2 in the conventional method of the present invention.

[Explanation of symbols]

1-1, 1-2: wireless stations # 1, # 2 2-3, 6-4: physical layers 2-4, 6-5: LLC (Logical Link Control) layers 2-5, 6-6: TCP / IP (Transmission Control Proto
col / Internet Protocol) layer 2-6, 6-7: application layer 10-1, 15-1: wireless station # 1 10-2, 15-2: wireless station # 2 3-3, 10-3, 15- 3: TCP / IP layer 3-4, 10-4, 15-4 of wireless station # 1: LLC layer 3-5, 10-5, 15-5 of wireless station # 1: wireless section 3-6, 10- 6, 15-6: LLC layer 3-7, 10-7, 15-7 of wireless station # 2: TCP / IP layer 3-8, 10-8, 15-8 of wireless station # 2: data packet A 3 -9, 10-9, 15-9: wireless packets (A-1, A-2, A-3) generated from data packet A 3-10, 10-10, 15-10: received by # 2 Wireless packets (A-1, A-2, A-3) 3-11, 10-11, 15-11: reproduced data packets A 3-12, 10-12, 15-12: data packets B 3 -13, 10-13, 15-13: wireless packets (B-1, B-2, B-3) generated from data packet B 3-14, 10-14, 15-14: received by # 2 Wireless packets (B-1, B-2) 3-15, 10-15, 15-15: Data packets B (retransmission) 3-16, 10-16, 15-16: wireless packets (B-1, B-2, B-3) generated from data packet B (retransmission) 3-17, 10-17, 15 -17: wireless packet (B-1, B-2, B-3) received at # 2 3-18, 10-18, 15-18: data packet B 4-1 to 4 reproduced at # 2 -9: Transmission flow of wireless station in the first embodiment (discard by timer) 4-10 to 4-16: Transmission flow of wireless station in the first embodiment (discard by retransmission data packet) 5-1: Wireless terminal (# 1 5-2: Base station (# 2) 5-3: Network 5-4: Wired terminal (# 3) 6-8: Data link layer 12-1: Wireless terminal (# 1) 12-2: Base station ( # 2) 12-3: Wired terminal (# 3) 7-4, 12-4: # 1 TCP / IP layer 7-5, 12-5: # 1 LLC layer 7-6, 12-6: Wireless Sections 7-7, 12-7: # 2 LLC layer 7-8, 12-8: # 2 data link layer 7-9, 12-9: Network section 7-10, 12-10: # 3 data link layer 7-11, 12-11: # 3 TCP / IP layer 7-12, 12-12: Data packet A 7-13, 12-13: Data packet Wireless packets (A-1, A-2, A-3) generated from A 7-14, 12-14: Wireless packets (A-1, A-
2, A-3) 7-15, 12-15: Data link layer packet A 7-16 generated in # 2, 12-16: Data link layer packet A 7-17, received in # 3 12-17: Data packets A 7-18, 12-18 reproduced in # 3: Data packets B 7-19, 12-19: Wireless packets (B-1, B-2, B-3) 7-20, 12-20: Wireless packets received in # 2 (B-1, B-
2) 7-21, 12-24: Data packet B (retransmission) 7-22: Wireless packet (B-1, B-2, B-3) generated from data packet B (retransmission) 7-23: # Wireless packets (B-1, B-2, B-
3) 7-24, 12-21: Data link layer packet B generated in # 2 7-25: Total delay D1 7-26: Wireless delay D2 8-1 to 8-9: Wireless terminal in the second embodiment / Transmission flow of wireless base station 9-1, 9-3 to 9-13: Flow of notification of allowable retransmission delay time of wireless terminal to wireless base station in embodiment 2 11-1 to 11-9: wireless in embodiment 3 Station transmission flow 12-22: Data link layer packet B received at # 3 B12-23: Data packet B 13-1 to 13-7 reproduced at # 3: Wireless terminal / wireless base in the fourth embodiment Station Transmission Flow 13-8 to 13-13: Management Flow of CRC Unit Storage Memory of Wireless Terminal / Wireless Base Station in Embodiment 4 14-1 to 14-9: Transmission of Wireless Terminal / Wireless Base Station in Embodiment 5 flow

Claims (7)

[Claims] 1. A system for performing wireless data communication between wireless stations, wherein the wireless station receives a delivery confirmation signal from a destination station of the data packet within a predetermined time when transmitting the data packet. If not, a data packet retransmission protocol for retransmitting the data packet is provided in an upper layer protocol, and a radio packet for transmitting a data packet on a radio channel is generated in a lower protocol layer of the data packet retransmission protocol. If it is not confirmed that the wireless packet has been correctly delivered to the destination wireless station, wireless data having a wireless packet retransmission protocol for performing retransmission on a wireless channel in a unit of the wireless packet independently of the data packet retransmission protocol In communication, in the wireless packet retransmission protocol If the elapsed time from the arrival of the data packet constituting the radio packet to the lower layer exceeds the predetermined time while retransmission of the radio packet is repeated, or if the data packet retransmission protocol is When retransmitting a packet, a radio packet retransmission method characterized by discarding all radio packets generated from the data packet. 2. A wireless terminal (hereinafter, wireless terminal A) comprising a wireless base station (hereinafter, wireless base station A) accommodating the wireless terminal A, and a network to which the wireless base station A is connected. Is another wireless terminal (hereinafter wireless terminal B) via the wireless base station A and the network,
Alternatively, in a system for performing wireless data communication with a wired terminal, a wireless terminal A receives a delivery confirmation signal from a wireless terminal B or a wired terminal within a predetermined time when transmitting a data packet. If not, it has a data packet retransmission protocol for retransmitting the data packet in an upper layer protocol, and generates a radio packet for transmitting a data bucket on a radio channel in a lower protocol layer of the data packet retransmission protocol; When it is not confirmed that the wireless packet has been delivered to the wireless base station A, in wireless data communication having a wireless packet retransmission protocol for performing retransmission on a wireless channel in a unit of the wireless packet independently of the data packet retransmission protocol, , The wireless terminal A transmits the data packet. And the time from when the wireless terminal B or the wired terminal receives the delivery confirmation signal for the data packet, and between the time when the wireless packet is transmitted and the time when the wireless packet is confirmed to be delivered to the wireless base station A. Using the time, a delay time in the network when transferring the data packet is estimated, and while the retransmission of the radio packet is repeated in the radio packet retransmission protocol, the data packet constituting the radio packet is transmitted to the lower layer. If the elapsed time from the arrival at the packet exceeds a value obtained by subtracting the transfer delay time in the network from the predetermined time (hereinafter referred to as “retransmission allowable time”), all radio packets generated from the data packet are discarded. A wireless packet retransmission method. 3. The wireless terminal A notifies the wireless base station A of the allowable retransmission time in advance, and the wireless terminal A
While the retransmission of the radio packet addressed to the radio terminal A is repeated in the radio packet retransmission protocol of the above, the elapsed time from when the data packet constituting the radio packet arrives at the radio base station A is 3. The wireless packet retransmission method according to claim 2, wherein when the notified retransmission allowable time is exceeded, all the wireless packets generated from the data packet are discarded. 4. The wireless packet retransmission protocol according to claim 1, wherein the data packet constituting the wireless packet is retransmitted while retransmission of the wireless packet is repeated. When the packet is transferred to the lower layer, the retransmitted data packet is divided, and among the newly generated wireless packets, only the wireless packet that has not been transmitted by the previous time is transmitted, and the wireless packet that has already been transmitted is transmitted. A wireless packet retransmission method characterized by discarding. 5. A system for performing wireless data communication between wireless stations, wherein a higher-layer protocol layer between the wireless stations transmits the data packet from a destination station within a predetermined time when transmitting the data packet. A data packet retransmission protocol for retransmitting the data packet when the acknowledgment signal is not received, and further dividing the data packet into a plurality of smaller radio packets in a lower protocol layer of the data packet retransmission protocol; If it is not confirmed that the wireless packet has been correctly delivered to the destination wireless station, in a wireless data communication having a wireless packet retransmission protocol for performing retransmission on a wireless channel in a unit of the wireless packet independently of the data packet retransmission protocol, , In the wireless packet retransmission protocol, If the data packet that constitutes the wireless packet is retransmitted and transferred to the lower layer within a certain period during the retransmission of the wireless packet and after the transmission of the wireless packet is completed, the retransmitted data A wireless packet retransmission method comprising discarding a packet. 6. A system for performing wireless data communication between wireless stations, wherein said wireless station transmits a data packet from a destination station of a destination packet of the data packet within a predetermined time when transmitting the data packet. Is not received, the upper layer has a data packet retransmission protocol for retransmitting the data packet, and the lower layer of the data packet retransmission protocol transmits a radio packet for transmitting the data packet on the radio channel. A wireless packet retransmission protocol for generating and retransmitting on a wireless channel in a unit of the wireless packet independently of the data packet retransmission protocol when it is not confirmed that the wireless packet has been correctly delivered to the destination wireless station. In wireless data communication, the predetermined period of time or Estimated using the fixed time and the time from transmitting at least the data packet by the wireless station to receiving an acknowledgment signal for the data packet from the destination station of the data packet,
A wireless packet retransmission method, wherein an upper limit of the number of retransmissions in the wireless packet retransmission protocol is determined based on a delay time when a data packet is transferred. 7. The wireless packet retransmission method according to claim 1, wherein the lower protocol layer receives a part of the data packet every time the lower protocol layer receives a data packet from the upper protocol layer. Generating an information block from all of the information blocks and storing the information block while the wireless packet is being retransmitted by the wireless packet retransmission protocol and for a predetermined period after the transmission of the wireless packet is completed; When a new data packet is received from an upper protocol layer to generate the information block, the information block is compared with the stored information block, and the newly generated information block matches the stored information block. , The new data packet is retransmitted by the wireless packet retransmission protocol Wireless packet retransmission method, characterized in that