JPH11252114A - Radio packet transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio packet transfer method by which possibility of packet transfer by a direct transfer method resulting in failure is low and packet transfer by the direct transfer method is conducted so long as it is possible. SOLUTION: In this radio packet transfer method, only radio terminals by which packet transfer by the direct transfer method is successful with a high possibility are registered in a direct transfer table based on a reception state or the like of a packet sent from radio terminals 1-4 toward optional radio terminals and received by its own station. Only the registered radio terminals are object of application by the direct transfer method and a relay transfer method via a radio base station 10 is applied to the other radio terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, there have been the following wireless packet transfer methods of this kind.

(1) Range LAN2 automatic switching method Range LAN2 is a 2.4 GHz band wireless LAN.
Product. In the Range LAN2, a relay transfer method in which a source wireless terminal transfers a packet to a destination wireless terminal via a wireless base station or a direct transfer method in which a source wireless terminal directly transfers a packet to a destination wireless terminal is selectively used. Then, packet transfer is performed. In this case, whether the packet transfer is performed by the relay transfer method or the direct transfer method is automatically switched on the transmission source wireless terminal side. The details are as follows.

When a packet to be transferred to another wireless terminal is generated, a source wireless terminal first transfers the packet directly to the destination wireless terminal by a direct transfer method. Thereafter, the source wireless terminal retransmits the packet if it does not receive a response signal from the destination wireless terminal within a certain period. Then, if the source wireless terminal does not receive a response signal even after transmitting the packet three times, it switches the packet transfer method for the destination wireless terminal to the relay transfer method. Thereafter, the source wireless terminal transfers the packet to the destination wireless terminal by the relay transfer method, and if the packet is not continuously transferred to the destination wireless terminal for a certain period of time, the source wireless terminal The packet transfer method for the wireless terminal is switched again to the direct transfer method.

(2) Fragment transmission method The IEEE802.11 committee is working on the development of wireless LAN standards. Then, the standard drafted by the committee supports the fragment division transmission method. In this fragment division transmission method, when a wireless terminal transmits a packet, if the packet exceeds a predetermined threshold (fragment threshold), the packet is divided and transmitted so that the packet length is equal to or less than the fragment threshold. I do. As a reference related to this technology, “IEEE P202.11, D
raft Standard For Wireless LAN Medium Access Contr
ol (MAC) and Physical Layer (PHY) Specification, D
6.1 ”.

(3) RTS / CTS Random Access Method The draft standard for wireless LAN established by the IEEE 802.11 committee supports the RTS / CTS random access method in addition to the fragment division transmission method.

In this RTS / CTS random access method, when a wireless terminal transmits a packet and the packet length of the packet exceeds a predetermined threshold (RTS threshold), an RTS for requesting a wireless channel reservation is made. An identifier (source address) of the source wireless terminal and the packet length are added to the (Request To Send) signal, and the signal is transmitted to the destination wireless terminal or the wireless base station.

[0008] The destination wireless terminal or the wireless base station uses the R
When the TS signal is received, a request for reservation of a wireless channel is permitted, and in order to notify the request to another wireless terminal or a wireless base station, the source address of the RTS signal is used as the permitted address, the packet length is used as the reservation period, and the CTS is used. (Clear To S
end) Add to the signal and transmit.

[0009] The source wireless terminal that has transmitted the RTS signal is:
When this CTS signal is received, it is determined whether or not the permission address indicated by the CTS signal matches the address of the source wireless terminal. If the addresses match, the packet is transmitted. If the addresses do not match, the packet and R are transmitted until the end of the reservation period.
Does not transmit the TS signal.

[0010] According to this method, after the receiving side broadcasts the reservation of the radio channel by the CTS signal, the transmitting side transmits the packet, so that the so-called hidden terminal problem can be solved. As a reference on this method, “IEEE P202.11, Draft Standard Fo
r Wireless LAN Medium Access Control (MAC) and Phy
sical Layer (PHY) Specification, D6.1 ”.

[0011]

The above-mentioned prior arts have the following problems.

(1) Problem of automatic switching method of Range LAN2

When packet transfer is performed between two wireless terminals that cannot perform direct transfer, the time required until the packet transfer is completed increases, and the throughput of the entire wireless packet system deteriorates.

For example, FIG. 45 shows an example of a situation where such a problem occurs. In the example shown in FIG.
The shield S is interposed between the wireless terminal a and the wireless terminal b, and the two cannot transfer directly. In such a case, for example, when the wireless terminal a
Assuming that the packet is transmitted to the wireless terminal b in accordance with the automatic switching method, the wireless terminal a performs the packet transfer by the direct transfer method three times, and then switches to the relay transfer method via the wireless base station 10. Therefore, the time required for the packet transfer to finally succeed becomes long. In addition, since the packet transfer is performed three times by the direct transfer method, there is a problem that wireless channel resources are wasted and the throughput of the entire wireless packet system is deteriorated. The above problems also occur in a network configuration in which a wireless base station is connected to a wired packet network. In this case, a wireless terminal located in the service area of the wireless base station cannot directly transfer with the wired terminal. However, Range
Assuming that the LAN2 automatic switching method is followed, even in such a case, the wireless terminal switches to the relay transfer method after trying the direct transfer to the wired terminal three times, which increases the time required for packet transfer. In addition, a problem of deterioration of the throughput of the entire wireless packet system occurs.

[0015] Once the switching from the direct transfer method to the relay transfer method is performed, even if the destination wireless terminal moves to a position where the source wireless terminal can directly transfer the data, the source wireless terminal and the destination wireless terminal are switched. The switching to the direct transfer method is not performed unless the communication with the device is continuously interrupted for a certain period or more. Therefore, wireless terminals that can directly transfer data uselessly perform communication using the wireless base station, which increases the packet transfer time through the wireless base station and reduces the transfer efficiency due to the consumption of wireless channel resources. There is a problem of causing a decrease.

Problems Related to Power Save Mode When a wireless terminal is operating in a power save mode in which a receiver is periodically turned on and off, packets may be transferred to the wireless terminal. In such a case, if a packet is transferred to the wireless terminal during a period in which the receiver of the wireless terminal is stopped, the packet is not received, and as a result, the wireless channel is wasted and the entire wireless packet system is There is a problem that the throughput is deteriorated.

Problems Related to Authentication of Wireless Terminals According to the Range LAN2 automatic switching method, it is possible that a wireless terminal transfers a packet to another wireless terminal whose authentication has been rejected by a direct transfer method. In this case, the packet is discarded on the side of the wireless terminal that has rejected the authentication, and as a result, the wireless channel is wasted and the throughput of the entire wireless packet system deteriorates.

Problems When Broadcasting There is a case where a broadcast for simultaneously transferring the same packet to a plurality of wireless terminals is performed. The above-mentioned Ra is added to the radio packet system in which the broadcast is performed.
Assuming that the n.g. LAN2 automatic switching method is applied, the packet to be broadcast (broadcast packet) is first transferred to each wireless terminal by the direct transfer method. There is a problem that a wireless terminal located at a position where transfer is not possible cannot receive a broadcast packet.

Problems when Switching of Radio Base Stations Occurs There are cases where a radio terminal moves and the radio base station that is located is switched. In this case, a wireless terminal that has performed packet transfer to a certain destination wireless terminal by a direct transfer method before the movement will perform packet transfer to the same destination wireless terminal by a direct transfer method after the movement. However, the switching of the wireless base station may make it difficult to transfer packets to and from the destination wireless terminal by the direct transfer method. In this case, the direct transfer fails and the wireless channel resources are wasted. There is a problem that the throughput of the entire wireless packet transfer system is deteriorated. In addition, when the channel frequency used for communication changes with the switching of the radio base station, the destination wireless terminal that has transferred the packet by the direct transfer method before the switching is directly transmitted to the destination wireless terminal with the new channel frequency after the switching. May fail when forwarding packets. Also in this case, there is a problem that wireless channel resources are wasted and the throughput of the entire wireless packet transfer system is deteriorated.

(2) Problem of Fragmented Transmission Method Generally, in wireless packet transfer, as the packet length increases, the probability that a packet error occurs in a wireless transmission path increases. According to the fragment division method, a packet exceeding the fragment threshold is transmitted after being divided so that the packet length is equal to or less than the fragment threshold, so that this problem can be solved.

However, when a packet is divided and transmitted, a header is added to each divided packet.
This is a factor that deteriorates the throughput.

Therefore, when the fragment division transmission method is applied, the error rate in the wireless transmission path of the target wireless packet transfer system is taken into consideration. Is smaller, it is desired to increase the fragment threshold.

In a wireless packet transfer system, a wireless base station is generally installed at a position such as a ceiling where a wireless terminal can be seen. On the other hand, the wireless terminal is used only at a low position such as on a desk. Therefore, a transmission path between the wireless terminals has a higher error rate than a transmission path between the wireless terminal and the wireless base station.

Therefore, in a wireless packet transfer system in which the wireless terminal switches between the relay transfer method and the direct transfer method, if the fragmentation threshold is set to a value suitable for the transmission path between the wireless terminal and the wireless base station, the direct transfer There is a problem that the packet error rate increases during packet transfer by the method and the throughput decreases. Conversely, if the fragment threshold is set to a value suitable for the transmission path between the wireless terminals, there is a problem in that the throughput is reduced due to the overhead due to packet division during the packet transfer by the relay transfer method.

(3) Problem of RTS / CTS random access method According to the RTS / CTS random access method, the receiving station transmits a CTS signal to declare reservation of a wireless transmission path, so that the so-called hidden terminal problem can be solved. Throughput can be improved. However, in this method, the RTS
It is necessary to exchange signals and CTS signals, and the overhead due to this causes deterioration of throughput.

Therefore, when the RTS / CTS random access method is applied, the probability of occurrence of a hidden terminal in the target wireless packet transfer system is taken into consideration. It is desired to reduce the influence of hidden terminals by reducing the probability of occurrence of hidden terminals, and to increase the RTS threshold when the probability of occurrence of hidden terminals is small, to suppress the overhead related to the transmission and reception of the RTS signal and the CTS signal and increase the throughput. .

As described above, the wireless base station is generally installed at a position such as a ceiling where the wireless terminal can be seen, and the wireless terminal is used only at a low position such as on a desk. Accordingly, the transmission path between the wireless terminals is more susceptible to the radio wave shield than the transmission path between the wireless terminal and the wireless base station, and the probability of occurrence of hidden terminals is high.

Therefore, in a wireless packet transfer system in which the wireless terminal switches and uses the relay transfer method and the direct transfer method, if the RTS threshold is set to a value suitable for the transmission path between the wireless terminal and the wireless base station, the direct transfer There is a problem that hidden terminals are likely to occur during packet transfer by the method, and the throughput is reduced. Conversely, if the RTS threshold is set to a value suitable for the transmission path between the wireless terminals, there is a problem in that the throughput decreases due to the overhead involved in transmitting and receiving the RTS signal and the CTS signal during packet transfer by the relay transfer method.

The above are the problems of the above-described prior arts.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to reduce the possibility that packet transfer by the direct transfer method will fail, and on the other hand, to reduce the possibility of the direct transfer method as much as possible. The present invention provides a wireless packet transfer method capable of performing packet transfer according to (1).

A second object of the present invention is to solve the problem that a packet is not received when a packet is transferred by the direct transfer method when the destination wireless terminal is operating in a power save mode, and high throughput is obtained. And
An object of the present invention is to provide a wireless packet transfer method capable of performing packet transfer in a packet transfer time as short as possible.

A third object of the present invention is to solve the problem that when a destination wireless terminal transmits a packet by the direct transfer method when authentication is not successful, the packet is discarded on the destination wireless terminal side, and high throughput is obtained. Another object of the present invention is to provide a wireless packet transfer method capable of performing packet transfer in a shortest possible packet transfer time.

A fourth object of the present invention is to provide a method for transmitting a broadcast packet by a direct transfer method.
An object of the present invention is to solve the problem that a wireless terminal that is not located at a position where direct transfer is possible cannot receive a broadcast packet, and to provide a wireless packet transfer method that can transfer a broadcast packet with high reliability.

A fifth object of the present invention is to provide a method for transmitting a packet to a destination wireless terminal when a source wireless terminal performing packet transfer by a direct transfer method switches radio base stations. This solves the problem that if the wireless terminal performs packet transfer to the same destination wireless terminal as before the switching by the direct transfer method, the transfer may fail, and a high throughput is obtained and the shortest possible packet is obtained. It is an object of the present invention to provide a wireless packet transfer method capable of performing packet transfer in a transfer time.

Further, a sixth object of the present invention is to solve the problem of deterioration in the effect of improving the throughput when the fragment division method is applied, to obtain a high throughput and to shorten the packet transfer time as short as possible. It is another object of the present invention to provide a wireless packet transfer method capable of performing packet transfer by using a wireless packet transfer method.

A seventh object of the present invention is to provide an RTS /
A wireless packet transfer method that solves the problem of deterioration in the effect of improving the throughput when the CTS random access method is applied, and that can achieve high throughput and perform packet transfer in the shortest possible packet transfer time. To provide.

[0037]

Means for Solving the Problems In order to achieve the first object, packet transfer by the direct transfer method is performed only for radio terminals which are likely to succeed in packet transfer by the direct transfer method, It is desired to provide a means for excluding a wireless terminal in which packet transfer by the direct transfer method may fail from being applied to the direct transfer method in advance.

In general, since a wireless terminal can move, even if the direct transfer to the destination wireless terminal succeeds at a certain time, the wireless terminal performs the same transfer to the same destination wireless terminal at another time thereafter. Direct transfer is not always successful. Conversely, even if the direct transfer performed to the destination wireless terminal at a certain time fails, the direct transfer performed to the same destination wireless terminal may succeed at another time thereafter. That is, the wireless terminal that is highly likely to succeed in the packet transfer by the direct transfer method is not fixed.

Therefore, when a certain wireless terminal becomes a wireless terminal which is likely to succeed in the packet transfer by the direct transfer method, this is immediately included in the target of the direct transfer method, and the certain wireless terminal uses the direct transfer method. If a wireless terminal has a high possibility of packet transfer failure, some means for immediately excluding it from the application of the direct transfer method is desired.

The invention according to claim 1 has been made in accordance with such a concept. When a wireless terminal transmits a packet addressed to another wireless terminal, the source wireless terminal transmits the packet to the wireless base station. A relay transfer method in which the wireless base station transmits the packet to the destination wireless terminal, or a direct transfer method in which the source wireless terminal directly transmits the packet to the destination wireless terminal. Is selected, the packet is transferred by the selected method, and the destination wireless terminal and the wireless base station transmit a response signal when the packet is received without error, and the source wireless terminal transmits the packet. If the response signal is received within a certain period after transmission, it is determined that packet transmission is completed. If the response signal is not received within a certain period after transmission of the packet, In the wireless packet transfer method for performing retransmission of the packet it is determined that the packet transmission not completed in the wireless terminal, a. Storing a direct transfer table identifying wireless terminals to which the direct transfer method can be applied; b. When transferring a packet to any other wireless terminal, if the destination wireless terminal is not registered in the direct transfer table, transfer the packet by the relay transfer method, and the destination wireless terminal If it is registered in the table, transfer the packet by the direct transfer method, c. Based on the reception status of a packet transmitted to an arbitrary wireless terminal at its own station, it is determined whether or not the transmission source wireless terminal of the packet satisfies a registration condition for being registered in the direct transfer table. If the registration condition is satisfied, register the source wireless terminal in the direct transfer table; d. At least one of a transmission result when the own station transmits a packet addressed to the wireless terminal registered in the direct transfer table or a reception state when the own station receives a packet transmitted from any wireless terminal to the wireless terminal. Based on the, it is determined whether or not a registration cancellation condition for canceling the registration of the wireless terminal in the direct transfer table is satisfied, and if the registration cancellation condition is satisfied, registration of the wireless terminal in the direct transfer table is performed. The gist is a wireless packet transfer method characterized by deletion.

According to this invention, only the wireless terminals which are likely to succeed when the packet transfer by the direct transfer method is performed can be registered in the direct transfer table. Only the registered wireless terminals are targeted. Packet transfer by the direct transfer method can be attempted.

In the present invention, whether or not a “wireless terminal likely to succeed when packet transfer is performed” is determined by the “reception status of a packet transmitted to an arbitrary wireless terminal at its own station” from the wireless terminal. Is determined based on "." In other words, if the reception status of the packet transmitted from a certain wireless terminal at the own station is good, the wireless terminal side also has a good condition even when the packet is transferred from the own station to the wireless terminal by the direct transfer method. Packet reception should be performed in a proper reception situation. Therefore, when the reception status of the packet is good, it is determined that the transmission source wireless terminal of the packet satisfies the “registration condition”, and the packet is directly registered in the transfer table.

Various criteria can be considered as to why the "reception situation" is good. For example, the reception level of a packet is sufficiently high, or the frequency of reception at a sufficient reception level is high. High, or the error rate of the received data is low.

In the present invention, whether or not to register a certain wireless terminal in the direct transfer table is determined not only by packets addressed to the own station but also by other wireless terminals. This is performed on the basis of the reception status of the “performed packet”. Therefore, according to the present invention, when a certain wireless terminal satisfies the above “registration condition”, it is possible to directly register in the transfer table as early as possible.

In some cases, the wireless terminal once registered in the direct transfer table may not be suitable as a target to which the direct transfer method is applied due to movement of the wireless terminal. In such a case, the wireless terminal in the direct transfer table may not be suitable. You need to delete your registration. The trigger for this registration deletion is a determination as to whether or not the above “registration deletion condition” is satisfied. This determination is made when “the own station transmits a packet to the wireless terminal registered in the direct transfer table. Or at least one of the reception conditions when the own station receives a packet transmitted from an arbitrary wireless terminal to the wireless terminal ”.

In the present invention, since the above-described procedures for registration and deregistration with respect to the direct transfer table are performed as needed, a wireless terminal which has a high possibility of succeeding when a packet transfer by the direct transfer method is performed is always performed. The packet is registered in the direct transfer table, and the packet transfer by the direct transfer method is performed only for the registered wireless terminal.

Therefore, according to the present invention, there is a low possibility that the packet transfer by the direct transfer method will end in failure. On the other hand, the packet transfer by the direct transfer method can be performed as much as possible, and a high throughput can be obtained. In addition, packet transfer can be performed in a transfer time as short as possible.

As described above, the determination as to whether or not the “registration condition” is satisfied based on the “reception status” can be performed by various methods. For example, the following method is the most simple and accurate method. Conceivable.

When a wireless terminal receives a packet transmitted to an arbitrary wireless terminal at a reception level equal to or higher than the threshold L1 by the same source wireless terminal for m consecutive times, the wireless terminal that is the source transmits the packet. It is determined that the registration condition is satisfied (claim 2). When a packet transmitted to an arbitrary wireless terminal is received by the same source wireless terminal at a reception level equal to or higher than the threshold L1 Q1 times out of P1 times (P1 ≧ Q1), the wireless terminal that is the transmission source receives the packet. It is determined that the registration condition is satisfied (claim 3). Packets transmitted to an arbitrary wireless terminal are continuously transmitted by the same source wireless terminal at a reception level equal to or higher than the threshold L1.
Upon receiving once or Q1 times out of P1 times (P1 ≧ Q1), it is determined that the wireless terminal that is the transmission source satisfies the registration condition (claim 4).

According to each of the above methods, by setting the threshold L1 to a reception level that satisfies the required packet error rate, the communication quality that satisfies the required packet error rate when the own station transfers the packet by the direct transfer method. Only wireless terminals that can be transferred can be registered in the direct transfer table and can be applied to the direct transfer method.

Various methods can be considered for the method of “determining whether or not the registration deletion condition is satisfied”. For example, the following method is considered to be a simple and accurate method.

When a packet is transferred by the direct transfer method and the same source wireless terminal determines that the packet transmission is not completed twice consecutively m2, it is determined that the destination wireless terminal satisfies the deregistration condition. Judge (claim 5). When a packet is transferred by the direct transfer method and the same source wireless terminal determines that the packet transmission is incomplete Q2 times out of P2 times (P2 ≧ Q2), the destination wireless terminal determines whether or not the packet is not registered. Is determined to be satisfied (claim 6). When a packet is transferred by the direct transfer method and the same source wireless terminal determines that packet transmission is incomplete m2 times or Q2 times during P2 times (P2 ≧ Q2), the destination wireless terminal is It is determined that the registration deletion condition is satisfied (claim 7).

When the same source wireless terminal receives a packet transmitted to an arbitrary wireless terminal by the wireless terminal registered in the direct transfer table at a reception level less than the threshold L2 m3 times in succession, the source Is determined to satisfy the registration deletion condition (claim 8). When the same source wireless terminal receives a packet transmitted by the wireless terminal registered in the direct transfer table addressed to an arbitrary wireless terminal at a reception level less than the threshold L2 Q3 times out of P3 times (P3 ≧ Q3) It is determined that the wireless terminal that is the transmission source satisfies the registration deletion condition (claim 9). Packets transmitted by the wireless terminal registered in the direct transfer table to an arbitrary wireless terminal are transmitted by the same source wireless terminal at a reception level less than the threshold L2 m3 times or Q3 times out of P3 times (P3 ≧ Q3 ) When receiving, it is determined that the wireless terminal that is the transmission source satisfies the registration deletion condition (claim 10).

For a fixed period, the wireless terminal registered in the direct transfer table does not receive a packet transmitted to an arbitrary wireless terminal, and transfers the packet to the registered wireless terminal to transmit the packet. When the registration is not completed once, it is determined that the registered wireless terminal satisfies the registration cancellation condition (claim 11).

The effect when each of the above methods is adopted will be described as follows.

If the direct transfer fails, it is very likely that the direct transfer to the same destination wireless terminal immediately after that will fail. According to (1) to (4) above, it is possible to delete the registration of the wireless terminal that is very likely to fail in the direct transfer and exclude the wireless terminal from the target of the direct transfer.

When the above conditions are adopted, the following specific effects can be obtained by adjusting the threshold value L1 used for determining the registration condition and the threshold value L2 used for determining the registration deletion condition. First, assuming that L1 = L2, when a wireless terminal registered in the direct transfer table moves to a position that does not satisfy the required quality at the time of direct transfer, the registration is deleted and the communication quality is maintained by switching to the relay transfer method. In addition, the throughput can be increased. When L2 is a reception level that satisfies the required packet error rate, and L1> L2, the frequency of switching between direct transfer and relay transfer can be suppressed, and the effect of the processing load associated with the switching on the wireless terminal can be reduced. Can be suppressed.

In the case where the above is adopted, the registration in the direct transfer table of the wireless terminal which is likely to have moved far from the position where the direct transfer is possible is deleted, and the wireless terminal is switched to the relay transfer. In addition, unnecessary packet transfer can be prevented, and the throughput can be increased.

The above-described determination methods for the registration deletion condition may be used in combination of a plurality of types in order to increase the accuracy of the determination.

Next, according to a twelfth aspect of the present invention, in the power saving mode, the radio terminal transmits to the radio base station a start and stop cycle of the receiver in a power save mode in which the start and stop of the receiver are periodically repeated. Notify, during communication, from the active mode to maintain the receiver in the active state to the power save mode, or vice versa, when switching from the power save mode to the active mode to the radio base station When the destination wireless terminal is in the power save mode when notifying the mode switching and transferring the packet to another wireless terminal, whether or not the destination wireless terminal is registered in the direct transfer table The packet is transferred by the relay transfer method irrespective of the method.
The gist of the present invention is a wireless packet transfer method according to any one of the first to fifth aspects.

According to this invention, when the destination wireless terminal is operating in the power save mode, the relay transfer method is applied even if the destination wireless terminal is directly registered in the transfer table. Therefore, according to the present invention, in addition to the effects of the first to twelfth aspects of the present invention, it is possible to avoid a situation in which a packet is transferred to a destination wireless terminal operating in a power save mode by a direct transfer method and fails. And the effect that the throughput can be improved can be obtained.

According to a thirteenth aspect of the present invention, when the wireless terminal transfers a packet to another wireless terminal, the wireless terminal performs authentication with the other wireless terminal. The packet transfer to the other wireless terminal is performed by the relay transfer method regardless of whether another wireless terminal is registered in the direct transfer table or not. The gist of the present invention is a wireless packet transfer method described in claim 1.

When the destination wireless terminal rejects the authentication, if the packet is transmitted by the direct transfer method, the packet is discarded on the destination wireless terminal side, thereby solving the problem. Packet transfer can be performed in the transfer time.

The invention according to claim 14 is characterized in that, when transferring a packet by broadcast, the wireless terminal transfers the packet by the relay transfer method. The gist of the present invention is a wireless packet transfer method according to the first aspect.

According to the invention, the relay transfer method is applied when transferring a broadcast packet, and the method according to claims 1 to 13 is applied when transferring a unicast packet. Thus, according to the present invention,
In addition to the effects of the first to thirteenth aspects, packet transfer can be performed by relay transfer even to a wireless terminal that cannot receive a broadcast packet when direct transfer is performed, thereby improving the reliability of packet transfer. The effect that it can be obtained is obtained.

In the invention according to claim 15, the wireless terminal detects whether the wireless terminal is located within the service area of the wireless base station or outside the service area, and is located outside the service area of the wireless base station. 2. The method according to claim 1, wherein the packet is transferred by the direct transfer method in the case.
The gist is the wireless packet transfer method according to any one of the fourteenth aspects.

According to this invention, when the wireless terminal is located outside the service area of the wireless base station, the packet is transmitted by the direct transfer method regardless of whether the destination wireless terminal is registered in the direct transfer table. Therefore, it is possible to prevent useless packet transfer by the relay transfer method, and to obtain an effect of improving the throughput and shortening the packet transfer time.

The invention according to claim 16 is characterized in that the wireless terminal deletes registration of all wireless terminals in the direct transfer table in accordance with switching of a wireless base station which is a destination. The gist is the wireless packet transfer method according to any one of claims 1 to 15.

In the prior art, when a source wireless terminal that is performing packet transfer to a certain destination wireless terminal by a direct transfer method switches between wireless base stations, the source wireless terminal determines whether or not the wireless base station before switching has changed. There is a problem that if packet transfer is performed to the same destination wireless terminal by the direct transfer method, the transfer may end in failure.
According to the present invention, after switching the radio base station,
First, since the relay transfer method is applied, this problem can be solved.

According to a seventeenth aspect of the present invention, when a wireless base station and a plurality of wireless terminals perform wireless packet communication and the wireless terminal transmits a packet, the packet length of the packet exceeds a preset fragment threshold. In a wireless packet transfer method for dividing and transmitting the packet so that the packet length is equal to or less than the fragment threshold, the wireless terminal transmits a packet to the wireless base station, and the wireless base station Separate fragment thresholds are used for packet transfer by the relay transfer method of transmitting the packet to the destination wireless terminal and packet transfer by the direct transfer method of transmitting the packet directly to the destination wireless terminal. The gist is a wireless packet transfer method characterized by the above.

According to the invention, a fragment threshold suitable for each of the case of the relay transfer method and the case of the direct transfer method can be used, so that the throughput can be improved.

According to an eighteenth aspect of the present invention, when a wireless base station and a plurality of wireless terminals perform wireless packet communication and the wireless terminal transmits a packet, the packet length of the packet exceeds a preset RTS threshold. The RTS signal is transmitted to a destination wireless terminal or the wireless base station by adding an identifier of the own station and the packet length to the RTS signal, and the destination wireless terminal or the wireless base station is transmitted by the source wireless terminal of the RTS signal. When permitting the transfer of the packet, the identifier and the packet length assigned to the RTS signal are assigned to the CTS signal as an allowed address and a reservation period, respectively, and transmitted. The wireless terminal that has transmitted the RTS signal, When receiving a CTS signal containing the address of the own station as the permission address, the packet is transmitted, and the address of the own station is used as the permission address. In the wireless packet transfer method for receiving the RTS signal and the packet until the period corresponding to the reservation period given to the CTS signal ends when the CTS signal is received, the wireless terminal includes the wireless base station. A packet is transmitted to the destination wireless terminal by the relay base station, and the packet is transmitted to the destination wireless terminal by the direct transfer method. In this case, a wireless packet transfer method is characterized in that different RTS thresholds are used for each case.

According to this invention, an RTS threshold suitable for each of the relay transfer method and the direct transfer method can be used, so that the throughput can be improved.

[0074]

Embodiments of the present invention will be described below with reference to the drawings.

A. FIG. 1 illustrates a configuration example of a network to which each embodiment of the present invention is applied. In this network, each of the wireless base stations 10, 10,... Accommodates a plurality of wireless terminals. The wireless base station 10 and the wired terminal 20 are connected by the Ethernet 30. Wireless terminals 1, 2, 3,
, And communication with the host (not shown) are performed via any of the radio base stations. In addition, the radio base stations 10, 10,.
... store the MAC addresses of the wireless terminals accommodated in the own station in the accommodated terminal table 11 respectively.

B. First Embodiment This embodiment is an embodiment of a wireless packet transfer system that implements the wireless packet transfer method according to claim 1, wherein the determination regarding the “registration condition” is performed according to the invention according to claim 2, The determination regarding the “registration deletion condition” is performed according to the invention according to claim 5.

FIG. 2 shows the format of a wireless packet exchanged between a wireless terminal and a wireless terminal and between a wireless terminal and a wireless base station in this embodiment, and FIG. Figure 2
(B) shows the format of the ACK signal (response signal). As shown in FIG. 2A, the data packet is
Header, data, and frame check sequence FC
S.

The header includes a destination address DA,
It includes a source address SA, a packet type (in the case of a data packet, the packet type is “0000”), and a transfer type.

Here, the destination address DA is the MAC address of the destination wireless terminal or wired terminal. The transmission source address SA is the MAC address of the transmission source wireless terminal or wired terminal. The transfer type is information for specifying the transfer method of the packet, and is set to “00” when the packet is transmitted from the wireless terminal to perform the direct transfer method. If it is transmitted from the wireless terminal to execute, "0"
It is set to "1", and is set to "10" when transmitted from the radio base station to execute the relay transfer method.

As shown in FIG. 2B, the ACK signal is composed of a destination address DA, a packet type (in the case of an ACK signal, the packet type is "0001"), and a frame check sequence FCS. I have.

FIG. 3 is a flowchart showing an example of a data packet receiving operation of the wireless terminal in the present embodiment. In the present embodiment, each wireless terminal stores a direct transfer table illustrated in FIG. The direct transfer table stores the MA of the wireless terminal determined to be capable of performing packet transfer from the wireless terminal by the direct transfer method.
The C address is a component. In the receiving operation of the wireless terminal according to the present embodiment, the MAC address of the wireless terminal is registered in the direct transfer table.
In this operation example, the determination of “registration conditions” as to whether or not to register a wireless terminal in the direct transfer table employs a method in which m1 = 1 in the invention according to claim 2. Of course, m1 may be 2 or more, and it is easy for those skilled in the art to change the flow of FIG. 3 so that the embodiment can be implemented in such a mode. Hereinafter, the details will be described with reference to the flow shown in FIG.

When the wireless terminal receives the data packet,
First, it is determined whether or not the frame check sequence FCS is normal (step S101). The result of this determination is “N
If "O", the packet is discarded (step S1).
10) After that, the reception process ends, and if “YES”, the process proceeds to step S102.

Next, in step S102, it is determined whether or not the transfer type of the received data packet is "10".
When the transfer type is “10”, the process proceeds to step S106, and when the transfer type is not “10”, the process proceeds to step S103.

Next, proceeding to step S103, it is determined whether or not the reception level of the data packet is equal to or higher than the threshold L1, and if the result of this determination is "NO", the flow proceeds to step S106 and "YES". In the case of step S1
Go to 04.

Next, in step S104, it is determined whether or not the source address of the data packet is directly registered in the transfer table, and the result of this determination is "YES".
In the case of, the process proceeds to step S106, and in the case of “NO”, the process proceeds to step S105. Next, in step S105, the source address of the data packet is directly registered in the transfer table. Then, the process proceeds to step S106.

As described above, when a data packet is received, its transfer type is “00” or “01”.
(That is, the data packet is transmitted from another wireless terminal by the direct transfer method or the relay transfer method), and the reception level is equal to or higher than the threshold L1, the transmission source of the data packet is Is directly registered in the forwarding table. In this case, the registration is performed irrespective of whether the data packet is addressed to the own station or another wireless terminal or the like.

Next, in step S106, it is determined whether or not the destination address of the data packet matches the address of the own station. If the result of this determination is "NO", the packet is discarded (step S110), and the receiving process is terminated. If "YES", the process proceeds to step S10.
Proceed to 7.

Next, in step S107, it is determined whether the transfer type of the data packet is "01". If the result of this determination is "YES", the packet is discarded (step S110), and the receiving process ends. Although the packet was transmitted from another wireless terminal to its own station, it should be transferred to its own station by the relay transfer method, and it is normally received via the wireless base station. That's why.

On the other hand, if the result of the determination in step S107 is “Y
ES ", that is, when the data packet is directly transferred from another wireless terminal to its own station (transfer type" 00 ") or when the data packet is transmitted from another wireless terminal via the wireless base station. If the packet has been relay-transferred to its own station (transfer type “10”), step S
Proceed to 108.

Next, in step S108, an ACK signal is transmitted. Here, when the received data packet is transmitted from another wireless terminal by the direct transfer method (transfer type “00”), an ACK signal is transmitted to the wireless terminal that is the source of the data packet. And the data packet is transmitted from the radio base station by the relay transfer method (transfer type “10”)
, An ACK signal is transmitted to the wireless base station.

Next, in step S109, the received data packet is transferred to the upper layer, and the reception processing ends.

In the above-described reception operation according to the present embodiment, by setting the threshold L1 to a reception level that satisfies the required quality, direct transmission and quality are not satisfied for radio terminals that satisfy the quality at the time of direct transmission. Relay transfer can be selected for the wireless terminal.

Next, referring to the flowchart shown in FIG.
The operation of transmitting a data packet by the wireless terminal according to the present embodiment will be described. The transmission operation includes a process of deleting the registration of the wireless terminal in the direct communication table. However, the determination according to claim 5 is a determination method regarding a “registration deletion condition” as to whether or not to delete the registration of a certain wireless terminal. The method is adopted.

First, when a request to transmit a data packet is generated, the wireless terminal first sets a built-in retry counter to "1" (step S201). Next, it is determined whether or not the destination address of the data packet is registered in the direct transfer table (step S202). If the result of this determination is “YES”, the flow proceeds to step S203, and if “NO”, the flow proceeds to step S210.

Next, from step S202 to step S20
In step 3, the direct transfer method is selected. Next, step S
The process proceeds to 204 and the transfer type “0” corresponding to the direct transfer method
"0" is set in the data packet, and the data packet is transmitted.

Then, the flow advances to step S205 to determine whether an ACK signal has been received from the destination wireless terminal. If the result of this determination is "YES", it is considered that the transmitted data packet has been normally received by the destination wireless terminal, and the transmission operation ends.

On the other hand, if the decision result in the step S205 is "NO", the process advances to a step S206 to decide whether or not the value of the retry counter is smaller than a predetermined threshold value m2. If the result of this determination is "YES", the value of the retry counter is incremented by "1" (step S207), and waits for a randomly determined standby time (step S208). Transmission is performed (step S204). Hereinafter, similarly,
If the ACK signal is not received from the destination terminal and the value of the retry counter is less than m2, step S2
07, S208 and step S204 are repeated.

If the value of the retry counter has reached the threshold value m2 without receiving the ACK signal, the process proceeds from step S206 to step S209. In step S209, the destination address of the data packet to be transmitted is deleted from the direct transfer table. This is because it is considered that it is difficult to transfer a packet to the wireless terminal having such a destination address by the direct transfer method. When the process in step S209 ends, the process proceeds to step S210. Note that, as described above, the process proceeds to step S210 in addition to the case where the process of step S209 is performed and the case where the destination address of the data packet is not directly registered in the transfer table.

Next, in step S210, a relay transfer method is selected. Next, the process proceeds to step S211, the transfer type “01” corresponding to the relay transfer method is set to the data packet, and the data packet is transmitted.

Then, the flow advances to step S212 to determine whether or not an ACK signal has been received from the destination radio base station.
If the result of this determination is "YES", it is considered that the transmitted data packet has been normally received, and the transmission operation ends.

On the other hand, if the decision result in the step S212 is "NO", the process advances to a step S213 to set the value of the retry counter to a predetermined maximum number of retransmissions N (however,
N> m2. ) Is determined. If the result of this determination is "YES", the value of the retry counter is increased by "1" (step S2).
14) Wait for a standby time determined at random (step S215), and transmit the data packet again (step S211). Hereinafter, similarly, when the ACK signal is not received from the destination wireless base station and the value of the retry counter is less than N, step S21
4. Steps S215 and S211 are repeated.

If the value of the retry counter has reached the maximum number of retransmissions N without receiving the ACK signal, the flow advances from step S213 to step S216 to discard the transmission data packet and end the transmission processing. .

According to the data packet transmission operation of the wireless terminal described above, even if the destination wireless terminal moves to a position where direct transfer is not possible, such as out of line of sight, during the communication of the source wireless terminal, the destination wireless terminal is not affected. The packet transfer method applied to the terminal can be changed from the direct transfer method to the relay transfer method.

Referring to the flowchart shown in FIG.
The packet relay operation of the wireless base station according to the present embodiment will be described. First, when the wireless base station receives a data packet transmitted from a wireless terminal and having a transfer type of “01” (that is, a data packet transmitted from the wireless terminal to perform the relay transfer method), An ACK signal is transmitted to the transmission source wireless terminal (step S301), and it is determined whether the destination of the received data packet is a wireless terminal accommodated in the wireless base station (step S302). Also, when receiving the data packet transmitted from the wired terminal, the wireless base station determines whether the destination of the data packet is a wireless terminal accommodated in the wireless base station (step S30).
2).

When the result of the determination in step S302 is "N
In the case of "O", the process ends without performing the packet relay operation.

On the other hand, when the determination result of step S302 is “YES”, that is, when the destination of the data packet received from the wireless terminal or the wired terminal is a wireless terminal accommodated in the wireless base station. Performs a relay operation of transferring the data packet to the destination wireless terminal according to the following procedure.

First, the flow advances to step S303, and the value of the retry counter is set to "1". Next, proceeding to step S304, the transfer type "1" indicating that the data packet is transmitted from the radio base station to execute the relay transfer method.
"0" is set in the data packet and transmitted to the destination wireless terminal.

Next, the process proceeds to step S305, where it is determined whether an ACK signal has been received from the destination wireless terminal. If the result of this determination is "YES", it is considered that the transmitted data packet has been normally received, and the relay operation ends.

On the other hand, if the decision result in the step S305 is "NO", the process advances to a step S306 to decide whether or not the value of the retry counter is smaller than a predetermined maximum retransmission number N. The result of this determination is “YE
In the case of "S", the value of the retry counter is incremented by "1" (step S307), and waits for a randomly determined standby time (step S308), and transmits the data packet again (step S304). . Less than,
Similarly, if no ACK signal is received from the destination wireless terminal and the value of the retry counter is less than N, steps S307, S308 and S304 are repeated.

If the value of the retry counter has reached the maximum number of retransmissions N without receiving the ACK signal, the flow advances from step S306 to step S309 to discard the data packet and end the relay processing. .

By the operation of the radio base station described above, the relay transfer of a data packet from a radio terminal to another radio terminal and the packet relay from a wired terminal to a radio terminal become possible.

Next, FIGS. 7 to 12 show various operation examples in the present embodiment. Hereinafter, a specific operation example of the present embodiment will be described with reference to these drawings.

First, the operation sequence diagram of FIG. 7 shows an operation example when a certain wireless terminal B transmits a data packet to the wireless terminal A registered in the direct transfer table. In this operation example, the wireless terminal A is registered in the direct transfer table of the wireless terminal B. Therefore, the wireless terminal B
Indicates that when a data packet to be transferred to the wireless terminal A occurs, the transfer type of the data packet is set to “00”.
, And the destination address is set as the MAC address of the wireless terminal A, and transmitted by the direct transfer method.

Upon receiving this data packet, wireless terminal A determines whether or not the received level is equal to or higher than threshold L1, and if it is lower than threshold L1, does not directly register in the transfer table. On the other hand, when the reception level is the threshold L
If it is 1 or more, the MA of the wireless terminal B that is the transmission source
Register the C address directly in the transfer table. Further, since the received data packet has the MAC address of the wireless terminal A as the destination address, the data packet is delivered to the upper layer, and the ACK signal is transmitted to the wireless terminal B that is the source of the data packet. Send.

The wireless terminal B recognizes that the data packet has been successfully transmitted by receiving the ACK signal, and ends the transmission processing.

As described above, according to the present embodiment, for a wireless terminal registered in the direct transfer table, the data packet is transferred to the destination wireless terminal by the direct transfer method without passing through the wireless base station. In addition, the overhead of the relay can be reduced and the time required for the transfer can be shortened.

Next, in the operation sequence diagram of FIG. 8, when the wireless terminal A transmits a data packet to the wireless terminal C registered in the direct transfer table, the wireless terminal B as a third party An operation example in the case of receiving a data packet addressed to the wireless terminal A and registering the wireless terminal A directly in the transfer table is shown.

In this operation example, the wireless terminal C is registered in the direct transfer table of the wireless terminal A. Therefore, when a data packet to be transferred to the wireless terminal C is generated, the wireless terminal A sets the transfer type of the data packet to “00” and sets the destination address to the MA of the wireless terminal C.
It is set as the C address and transmitted by the direct transfer method.

Upon receiving this data packet, radio terminal C transmits an ACK signal to radio terminal A. Upon receiving the ACK signal, the wireless terminal A recognizes that the transmission of the packet data has been successful, and ends the transmission processing.

On the other hand, if the wireless terminal B is located in a place where the wireless terminal A has a good view, the data packet addressed to the wireless terminal C transmitted from the wireless terminal A is received by the wireless terminal B as a third party. May be done. In this case, the wireless terminal B determines whether or not the reception level of the data packet is equal to or higher than the threshold L1.
Is directly registered in the forwarding table. Also, the received data packet is destined for the wireless terminal C and is discarded. On the other hand, when the reception level is less than the threshold value L1, registration in the direct transfer table is not performed.

As described above, in the present embodiment, when a wireless terminal receives a data packet addressed to another wireless terminal, if the received level is equal to or higher than a predetermined threshold, the wireless terminal that is the transmission source is directly Register in the forwarding table. Therefore, only the highly probable wireless terminal that can perform direct transfer with a predetermined communication quality when the destination of the direct transfer is used is registered in the direct transfer table. Frequency can be reduced.

Next, the operation sequence diagram of FIG. 9 shows an operation example in the case where the relay transfer is performed from the wireless terminal A to the wireless terminal B via the wireless base station. In this operation example, the MAC address of the wireless terminal B is not registered in the direct transfer table of the wireless terminal A. Therefore, when a data packet to be transmitted to the wireless terminal B occurs, the wireless terminal A selects the relay transfer method, sets the destination address to the MAC address of the wireless terminal B, sets the transfer type to “01”, and sets the transfer type to “01”. Send a data packet.

When receiving the data packet, the radio base station transmits an ACK signal to radio terminal A because the transfer type is “01”.

Wireless terminal A receives this ACK signal, recognizes that the transmission was successful, and ends the transmission processing.

On the other hand, since the destination of the data packet is the radio terminal B accommodated in the radio base station, the radio base station sets the transfer type of the data packet to “10” and transmits the data packet. Do.

When wireless terminal B receives this data packet, it transfers the data packet to the upper layer because its transfer type is "10" and its destination address matches the address of its own station. , ACK signal to the radio base station. The wireless base station recognizes the successful transmission of the data packet by receiving the ACK signal, and ends the transmission processing.

Next, in the operation sequence diagram of FIG. 10, the wireless terminal A transfers the data packet to the wireless terminal B registered in the direct transfer table by the direct transfer method. An operation example in the case of switching is shown. In this operation example, m2 = 1.

In this operation example, the MAC address of the wireless terminal B is registered in the direct transfer table of the wireless terminal A. Therefore, when a data packet to be transmitted to the wireless terminal B occurs, the wireless terminal A selects the direct transfer method, sets the destination address to the MAC address of the wireless terminal B, sets the transfer type to “00”, and Send a data packet.

However, at this time, for example, if the wireless terminal B moves out of sight of the wireless terminal A, the transmission of the data packet ends in failure. In this case, while the value of the retry counter is less than the threshold value m2, the data packet is retransmitted.
, Wireless terminal A deletes the registration of wireless terminal B in the direct transfer table.

Thereafter, the radio terminal A transmits the data packet addressed to the radio terminal B with the transfer type being "01".

When receiving the data packet, the radio base station transmits an ACK signal to radio terminal A because the transfer type is “01”.

Wireless terminal A receives this ACK signal, recognizes that the transmission was successful, and ends the transmission processing.

On the other hand, since the destination of the data packet is the wireless terminal B accommodated in the wireless base station, the wireless base station sets the transfer type of the data packet to “10” and transmits the data packet. Do.

When wireless terminal B receives this data packet, it transfers the data packet to the upper layer because its transfer type is "10" and its destination address matches the address of its own station. , ACK signal to the radio base station. The wireless base station recognizes the successful transmission of the data packet by receiving the ACK signal, and ends the transmission processing.

Each of the operation examples described above is for the case where the destination wireless terminal and the source wireless terminal are accommodated in the same wireless base station. As shown in FIG. In the case where the wireless terminal A and the wireless terminal B performing the above are respectively accommodated in two adjacent wireless base stations, the same registration and deregistration of the direct transfer table as described above are performed, and the direct transfer method or the relay transfer method is used. Packet transfer can be performed.

Next, the operation sequence diagram of FIG.
5 shows an operation example in the case where packet transfer is performed from the wireless terminal A to the wired terminal Z in FIG. First, it is assumed that a data packet to be transmitted to the wired terminal Z occurs in the wireless terminal A. In this case, since the wired terminal Z is not registered in the direct transfer table of the wireless terminal A, the wireless terminal A
Select the relay transfer method and set the destination address to M of the wired terminal Z.
An AC address is transmitted, and the transfer type is transmitted as "01".

Upon receiving this data packet, the radio base station determines that the transfer type is "01".
The K signal is transmitted to the transmission source wireless terminal A. Wireless terminal A
The reception of this ACK signal recognizes the success of transmission, and ends the transmission processing.

On the other hand, since the destination address of the data packet is not for the wireless terminal accommodated in the wireless base station, the wireless base station converts the data packet into an Ethernet packet and transmits it to Ethernet.

When receiving the Ethernet packet via the Ethernet, the wired terminal Z delivers the Ethernet packet to the upper layer because the destination address and the address of the local station match.

As described above, according to the present embodiment, even when the destination is a wired terminal, packet transfer to the wired terminal by the relay transfer method can be performed without causing useless retransmission packets due to direct transfer. Can be.

As described above, the embodiment of the invention according to claim 1 is
The case where the determination regarding “registration condition” is performed by the determination method according to claim 2 and the determination regarding “registration deletion condition” is performed by the determination method according to claim 5 has been described as an example. But,
The determination method regarding the “registration condition” and the “registration deletion condition” adopted in the present embodiment is merely an example. In carrying out the present invention, the determining method according to claim 3 or 4 may be adopted instead of the determining method according to claim 2, and the claim may be substituted for the determining method according to claim 5. The determination method according to 6 or 7 may be adopted.

C. Second Embodiment This embodiment is a wireless packet transfer method according to claim 1, wherein the determination regarding “registration conditions” is performed by the determination method according to claim 2, and the determination regarding “deregistration conditions” is performed. The determination method according to the fifth aspect and the determination method according to the eighth aspect are performed in combination.

In the present embodiment, the format of a wireless packet exchanged between a wireless terminal and a wireless terminal and between a wireless terminal and a wireless base station is shown in FIG. 2 as in the first embodiment. As expected. Further, as in the first embodiment, each wireless terminal stores the direct transfer table illustrated in FIG. 4 and selects a direct transfer method or a relay transfer method according to the registered contents of the direct transfer table.

FIG. 13 is a flowchart showing a data packet receiving operation of the wireless terminal in this embodiment. In this receiving operation, the determination regarding the “registration condition” is performed by the determination method with m1 = 1 in claim 2, and the determination on the “deregistration condition” is performed with the determination method with m3 = 1 in claim 8. Needless to say, m1 or m3 may be two or more, and it is easy for those skilled in the art to change the flow of FIG. 13 so as to implement in such an embodiment.

When the wireless terminal receives a data packet, it first determines whether or not the frame check sequence FCS of the data packet is normal (step S301). Then, the frame check sequence FC
If S is normal, the process proceeds to step S402. If an abnormality is found in the frame check sequence FCS, the received data packet is discarded (step S413), and the receiving process ends.

At step S402, it is determined whether the transfer type of the received data packet is "10". If this determination is "YES", the flow proceeds to step S409.

On the other hand, when the received data packet is received from the wireless terminal to perform the direct transfer method (transfer type = “00”), or when the data packet is transmitted wirelessly to perform the relay transfer method. If it is received from the terminal (transfer type = “01”), the determination result of step S402 is “NO” and the
03.

Next, in step S403, it is determined whether or not the reception level at the time of receiving the data packet is equal to or higher than the threshold value L1. If the result of this determination is "YES", the flow proceeds to step S404, and it is determined whether or not the source address of the data packet is registered in the direct transfer table of the wireless terminal. If the result of this determination is "NO", the source address is directly registered in the transfer table (step S405), and step S4
Go to 09. If the result of the determination in step S404 is "YES", the process proceeds to step S4 without directly registering in the transfer table (step S405).
Go to 09.

On the other hand, if the reception level of the data packet is lower than the threshold L1, the process proceeds from step S403 to step S406, and it is determined whether the reception level of the data packet is higher than the threshold L2. If the reception level is equal to or higher than the threshold L2, the process proceeds to step S409. On the other hand, if the reception level is less than the threshold L2, it is determined whether or not the source address of the data packet is registered in the direct transfer table of the wireless terminal (step S407). If the result of this determination is "YES", the registration of the source address in the direct transfer table is deleted (step S40).
8), proceed to step S409. Note that the above step S
If the determination result at 407 is “NO”, the process proceeds to step S409 without executing the registration deletion in the direct transfer table (step S408).

As described above, when a data packet is received in the present embodiment, the transfer type is “0”.
0 "or" 01 "(that is, the data packet is transmitted from another wireless terminal by the direct transfer method or the relay transfer method) and the reception level is equal to or more than the threshold L1. The source wireless terminal of the data packet is directly registered in the transfer table, and a data packet whose transfer type is “00” or “01” is received, and the reception level at that time is set to a threshold L.
If it is less than 2, the registration of the source wireless terminal of the data packet in the direct transfer table is canceled. In this case, registration and deregistration are performed regardless of whether the data packet is addressed to the own station or another wireless terminal or the like.

Next, in step S409, it is determined whether or not the destination address of the data packet matches the address of the own station. If the determination is "NO", the packet is discarded (step S413), and the receiving process is terminated. If the determination is "YES", the process proceeds to step S41.
Go to 0.

Next, in step S410, it is determined whether the transfer type of the data packet is "01". If the result of this determination is "YES", the packet is discarded (step S413), and the receiving process ends. Although the packet was transmitted from another wireless terminal to its own station, it should be transferred to its own station by the relay transfer method, and it is normally received via the wireless base station. That's why.

On the other hand, if the result of the determination in step S410 is "N
O ”, that is, when the data packet is directly transferred from another wireless terminal to the own station (transfer type“ 00 ”), or when the data packet is transferred from another wireless terminal via the wireless base station. If the packet has been relay-transferred to its own station (transfer type "10"), step S41
Proceed to 1.

Next, in step S411, an ACK signal is transmitted. Here, when the received data packet is transmitted from another wireless terminal by the direct transfer method (transfer type “00”), an ACK signal is transmitted to the wireless terminal that is the source of the data packet. And the data packet is transmitted from the radio base station by the relay transfer method (transfer type “10”)
, An ACK signal is transmitted to the wireless base station.

Next, in step S412, the received data packet is transferred to the upper layer, and the reception processing ends.

In the above-described receiving operation according to the present embodiment, by setting the thresholds L1 and L2 to a receiving level that satisfies the required quality, the direct transfer and the quality can be reduced for a wireless terminal that satisfies the direct transfer quality. Relay transfer can be selected for wireless terminals that do not satisfy the condition. By setting L1> L2, the frequency of switching between direct transfer and relay transfer can be suppressed. Therefore, when the control load associated with switching between direct transfer and relay transfer is large, the effect on the wireless terminal can be suppressed.

FIG. 14 shows a state in which the radio terminal A is registered in the direct transfer table of the radio terminal B and the radio terminal B is registered in the direct transfer table of the radio terminal A.
7 shows an example of an operation sequence when a packet transfer from the wireless terminal A to the wireless terminal B is performed by the direct transfer method.

As shown in FIG. 14, radio terminal B
Upon receiving a packet from wireless terminal A, it determines whether or not the received level is equal to or higher than threshold L2. Here, the wireless terminal A and the wireless terminal B have been communicating by the direct transfer method up to that point. However, if the wireless terminal B moves far away from the wireless terminal A, The reception level may be less than the threshold L2. In such a case, the wireless terminal B deletes the registration in the direct transfer table of the wireless terminal A that is the transmission source of the packet. In addition, the received packet is delivered to an upper layer, and an ACK signal is transmitted to wireless terminal A.

As described above, according to the present embodiment, communication performed when direct transfer is performed to the wireless terminal due to, for example, deterioration of the relative positional relationship with the wireless terminal registered in the direct transfer table. When quality is expected to decline,
The registration of the wireless terminal in the direct transfer table is deleted, and the packet transfer to the wireless terminal is performed by the relay transfer method that can maintain the required quality.

Although the characteristic operation example of the present embodiment has been described above, other operations are the same as those of the above-described first embodiment. That is, the flow of the packet transmission operation of the wireless terminal in the present embodiment is already shown in FIG.
Is the same as that described with reference to FIG. As described above, in the packet transmission operation shown in FIG.
Is determined by the determination method according to the above. Therefore, in the present embodiment, in the reception operation of the wireless terminal (FIG. 13), the determination regarding the “registration deletion condition” is performed according to the determination method according to claim 8, and in the transmission operation of the wireless terminal, the determination method according to claim 5 is performed. Is determined in accordance with the above. Instead of using the determination method according to claim 8 and the determination method according to claim 5 in this way, only the determination method according to claim 8 is used, and the determination by the determination method according to claim 5 is omitted. You may.

The operation flow of the packet relay of the radio base station in this embodiment is the same as that already described with reference to FIG. The operation sequence example in the case where the wireless terminal transmits a packet to the wireless terminal registered in the direct transfer table is the same as that shown in FIG. 7 described above. 8 is the same as the operation sequence shown in FIG. Further, an example of an operation sequence when the wireless terminal transmits a packet to a wireless terminal not directly registered in the transfer table is the same as that shown in FIG. 9 described above. Further, for example, the operation sequence when the wireless terminal B is registered in the direct transfer table of the wireless terminal A and the wireless terminal B cannot receive the packet transmitted from the wireless terminal A is the one shown in FIG. Is the same as Also, as illustrated in FIG. 11 above, even when the wireless terminal A and the wireless terminal B that exchange data packets are accommodated in two adjacent wireless base stations, the same direct transfer table as described above is used. Registration and deregistration can be performed, and packet transfer can be performed by the direct transfer method or the relay transfer method. The operation sequence when a wireless terminal and a wired terminal perform packet transfer is the same as that shown in FIG.

As described above, the determination regarding the “registration condition” is performed by the determination method according to claim 2, and the determination regarding the “registration deletion condition” is performed using both the determination method according to claim 5 and the determination method according to claim 8. The present embodiment has been described by taking the case as an example. However, the judgment method according to claim 3 or 4 is used instead of the judgment method according to claim 2, or the claim is used instead of the judgment method according to claim 5. The determination method according to claim 6 or 7 may be used, or the determination method according to claim 9 or 10 may be used instead of the determination method according to claim 8. Further, as described above, the determination by the determination method according to claim 5 may be omitted.

D. Third Embodiment In the present embodiment, the format of a wireless packet exchanged between a wireless terminal and a wireless terminal and between a wireless terminal and a wireless base station is shown in FIG. As expected. Also, as in the above embodiments, each wireless terminal stores the direct transfer table illustrated in FIG. 4 and selects a direct transfer method or a relay transfer method according to the registered contents of the direct transfer table. In this embodiment, a monitoring timer is prepared for each wireless terminal registered in the direct transfer table. How to use these monitoring timers will be clarified in the description of the operation of the present embodiment.

In this embodiment, the registration conditions for the wireless terminal to directly register the MAC address of an arbitrary wireless terminal in the transfer table are the same as those described in the above embodiments.

On the other hand, from the direct transfer table,
With regard to the registration deletion condition for deleting the AC address, this embodiment requires that any one of the following conditions be satisfied.

Deregistration condition: A situation in which a packet is transferred from its own station to the wireless terminal by a direct transfer method and packet transmission is not completed occurs at a frequency exceeding a predetermined limit. 7).

Deregistration condition: A situation in which the own station receives a packet transmitted by the wireless terminal at a reception level less than a predetermined threshold has occurred at a frequency exceeding a predetermined limit. Equivalent).

Deregistration condition: A situation in which the own station receives a packet transmitted by the wireless terminal at a reception level equal to or higher than a predetermined threshold for a certain period does not occur at all, and the own station transmits a packet to the wireless terminal. Packet transmission is completed, and the situation that the packet transmission is completed does not occur once (corresponding to claim 11).

Of the above, the registration deletion condition and the above are also adopted in the second embodiment. In the present embodiment, in addition to the above, the above-described registration deletion condition is adopted.

FIGS. 15 and 16 are flowcharts showing the operation of receiving a data packet by the wireless terminal in the present embodiment. The flow of this receiving operation is substantially the same as the flow of the data packet receiving operation of the wireless terminal according to the second embodiment (FIG. 13). However, steps S405 and S408 in FIG. 13 are replaced with steps S405A and S408A in the present embodiment due to the addition of the above-described registration deletion condition.
421A to S423A are added. Other steps are the same as those in FIG. For these, the same step numbers as those used in FIG. 13 are used.

The key points of the data packet receiving operation of the radio terminal according to the flow of FIG. 15 and FIG. 16 will be described as follows.

When the wireless terminal receives a data packet whose transfer type is "00" or "01" and whose reception level is equal to or greater than the threshold value L1, it directly sends the address of the source wireless terminal of the data packet to the transfer table. Register with
The monitoring timer corresponding to the source wireless terminal is started (steps S401, S402, S403, S40).
4, S405A). However, when the address of the transmission source wireless terminal of the data packet is already registered in the direct transfer table, only the process of restarting the monitoring timer is performed (steps S401, S402, S403, S403).
404, S421A).

When the wireless terminal receives a data packet whose transfer type is "00" or "01" and whose reception level is less than the threshold value L2, the source wireless terminal of the data packet in the direct transfer table The registration of the address is deleted, and the monitoring timer corresponding to the transmission source wireless terminal is stopped (steps S401, S402, and S4).
03, S406, S407, S408A).

When the wireless terminal receives a data packet whose transfer type is “00” or “01” and whose reception level is equal to or greater than the threshold L2, the address of the source wireless terminal of the data packet is directly If it has already been registered in the transfer table, the monitoring timer is restarted (steps S401, S402, S403, S406,
S422A, S423A).

The above is the contents of the processing related to the direct transfer table and the processing related to the monitoring timer performed in response to the reception of the data packet by the wireless terminal. After completing these processes, the wireless terminal determines whether or not the data packet is a data packet of the transfer type “00” or “10” addressed to its own station (steps S409 and S410), and this determination result Is affirmative, the ACK signal is transmitted and the data packet is delivered to the upper layer (step S412). The processing after step S409 is not different from the second embodiment.

Next, FIG. 17 is a flowchart showing a data packet transmission operation of the wireless terminal in the present embodiment. The flow of this transmission operation is almost the same as the flow of the data packet transmission operation of the wireless terminal in the first embodiment (FIG. 5). However, due to the addition of the above-mentioned registration deletion condition, step S209 in FIG.
A, and a new step S221A is added in the present embodiment. The other steps are the same as those in FIG. For these, the same step numbers as those used in FIG. 5 are used.

The main points of the data packet transmission operation of the wireless terminal according to the flow of FIG. 17 will be described as follows.

When the wireless terminal receives the ACK signal after transmitting the data packet whose transfer type is "00" (direct transfer), it restarts the monitoring timer corresponding to the destination wireless terminal (steps S201 and S202). , S203,
S204, S205, S221A).

However, the transfer type is “00” (direct transfer)
When the wireless terminal does not receive the ACK signal for m2 consecutive times after the wireless terminal transmits a data packet of
The registration of the address of the destination wireless terminal in the direct transfer table is deleted, and the monitoring timer corresponding to the destination wireless terminal is stopped (steps S205 and S20).
6, S209A).

In this case, the retransmission of the data packet
Performed by the relay transfer method (steps S210 to S21)
6). Note that this relay transfer method is the same as that described in the first embodiment, and a description thereof will not be repeated.

As described above, the wireless terminal according to the present embodiment measures the time by the monitoring timer for each wireless terminal whose address is registered in the direct transfer table (step S405A in FIG. 15). Then, when any of the monitoring timers has timed out, the wireless terminal according to the present embodiment executes the monitoring timer over routine shown in FIG. 18 and directly stores the address of the wireless terminal corresponding to the timed out monitoring timer in the direct transfer table. Remove from.

Here, when the monitoring timer that has started measuring time receives a data packet from the wireless terminal corresponding to the monitoring timer at a reception level equal to or higher than the threshold L1 (step S421A in FIG. 15), the monitoring timer corresponds to the monitoring timer. When a data packet is received from the wireless terminal at a reception level equal to or higher than the threshold L2 and the wireless terminal is registered in the direct transfer table (step S423A in FIG. 15), or is directly transferred to the wireless terminal corresponding to the monitoring timer When a data packet is transmitted by the method and an ACK signal is received (step S221A in FIG. 17), the process is restarted.

Therefore, a data packet is not received at a reception level equal to or higher than the threshold value L1 or L2 from the wireless terminal corresponding to the monitoring timer for a certain period of time (timer setting time of the monitoring timer). In addition, there is a case where a data packet is transmitted to the wireless terminal corresponding to the monitoring timer by a direct transfer method, and the data packet is successfully completed.
If this does not occur (the above-described registration deletion condition), the monitoring timer times out, and the registration of the wireless terminal corresponding to the monitoring timer in the direct transfer table is released.

Next, various operation examples of the present embodiment will be described more specifically with reference to the respective operation sequence diagrams of FIG. 19 to FIG.

First, FIG. 19 shows an operation sequence when the wireless terminal transfers a data packet to the wireless terminal registered in the direct transfer table by the direct transfer method.

In FIG. 19, the wireless terminal A is registered in the direct transfer table of the wireless terminal B. For this reason,
When a data packet to be transferred to the wireless terminal A occurs in the wireless terminal B, the wireless terminal B selects the direct transfer method, sets the destination address to the MAC address of the wireless terminal A, sets the transfer type to “00”, and sets the transfer type to “00”. Send a data packet.

Upon receiving this data packet, radio terminal A determines the reception level, and if the reception level is equal to or greater than threshold L1, registers the MAC address of source radio terminal B directly in the transfer table, and Starts the monitoring timer corresponding to.

Since the transfer type of the received data packet is “00” and its destination address matches the MAC address of the wireless terminal A,
An ACK signal is transmitted to the transmission source wireless terminal B, and the data packet is delivered to an upper layer.

When receiving the ACK signal, the wireless terminal B recognizes that the data packet transmission to the wireless terminal A by the direct transfer method has succeeded, and restarts the monitoring timer corresponding to the wireless terminal A.

FIG. 20 shows an operation sequence in the case where a wireless terminal receives a data packet transmitted to another wireless terminal and directly registers the source wireless terminal of the data packet in the transfer table. Is shown.

In FIG. 20, wireless terminal C is registered in the direct transfer table of wireless terminal A. For this reason,
When a data packet to be transferred to the wireless terminal C occurs at the wireless terminal A, the wireless terminal A selects the direct transfer method, sets the destination address to the MAC address of the wireless terminal C, sets the transfer type to “00”, and sets the transfer type to “00”. Send a data packet.

Upon receiving this data packet, radio terminal C transmits an ACK signal to source radio terminal A. By receiving the ACK signal, the wireless terminal A recognizes that the data packet transmission to the wireless terminal C by the direct transfer method has been successfully completed.

Incidentally, there is a case where the data packet addressed to the wireless terminal C is received by the wireless terminal B as a third party.

In this case, radio terminal B determines whether the reception level is equal to or higher than threshold value L1. If the reception level is equal to or higher than the threshold value L1, the MAC address of the transmission source wireless terminal A of the data packet is directly registered in the transfer table, and the monitoring timer corresponding to the wireless terminal A is started. Further, the received data packet is destined for the wireless terminal C, and thus is discarded.

Next, FIG. 21 shows that the wireless terminal receives a data packet transferred by the direct transfer method, and the reception level at that time is less than the threshold value. 7 shows an operation sequence for deleting registration in the direct transfer table.

In FIG. 21, the MAC address of wireless terminal B is registered in the direct transfer table of wireless terminal A, and the M address of wireless terminal A is registered in the direct transfer table of wireless terminal B.
AC address is registered. Therefore, the wireless terminal A
, When a data packet to be transferred to the wireless terminal B occurs, the wireless terminal A selects the direct transfer method, sets the destination address to the MAC address of the wireless terminal B, sets the transfer type to “00”, and transfers the data packet. Send.

Upon receiving this data packet, radio terminal B determines the reception level, and if the reception level is less than threshold value L2, deletes the MAC address of source radio terminal A from the direct transfer table, and returns to radio terminal A. Stop the monitoring timer corresponding to.

Since the transfer type of the received data packet is “00” and the destination address matches the MAC address of the wireless terminal B,
An ACK signal is transmitted to the source wireless terminal A, and the data packet is delivered to the upper layer.

Upon receiving this ACK signal, wireless terminal A recognizes that the data packet transmission to wireless terminal B by the direct transfer method has succeeded, and restarts the monitoring timer corresponding to wireless terminal B.

Next, FIG. 22 shows an example of an operation sequence in the case where the monitoring timer corresponding to a certain wireless terminal has timed out in the wireless terminal.

In FIG. 22, the MAC address of wireless terminal B is registered in the direct transfer table of wireless terminal A. Therefore, in the wireless terminal A, time measurement is performed by the monitoring timer corresponding to the wireless terminal B. Then, in the example shown in FIG. 22, the data packet addressed to the wireless terminal A is transmitted three times from the wireless terminal B by the direct transfer method, but all of them fail. Therefore, in the wireless terminal A, the monitoring timer corresponding to the wireless terminal B times out, and the wireless terminal A
Deletes the registration of the wireless terminal B in the direct transfer table.

Thereafter, a data packet to be transferred to wireless terminal B occurs at wireless terminal A. However, at this time, since the wireless terminal B is not registered in the direct transfer table of the wireless terminal A, the wireless terminal A transfers the data packet addressed to the wireless terminal B by the relay transfer method.

As described above, in the present embodiment, even if a wireless terminal is directly registered in the transfer table,
After that, if the data packet transmitted from the wireless terminal is not received for a certain period of time or more, and there is no possibility that the direct transfer to the wireless terminal succeeds, the cause of the movement of the wireless terminal, etc. It is considered that the direct transfer method has become difficult to apply, and the registration of the wireless terminal in the direct transfer table is deleted. Thereafter, the data packet addressed to the wireless terminal is transferred by the relay transfer method.

The characteristic operation example of this embodiment has been described above. Other operations are the same as those of the above-described first and second embodiments.

E. Fourth Embodiment The present embodiment is an embodiment in which the present invention is applied to a wireless packet transfer system including wireless terminals having two types of modes, a power save mode and an active mode. It is a form.

FIG. 23 shows a wireless packet format exchanged between a wireless terminal and a wireless terminal and between a wireless terminal and a wireless base station in this embodiment, and FIG. Format, Figure 23
(B) is the format of the ACK signal.

As shown in FIG. 23A, the data packet in the present embodiment contains a power save mode flag. When transitioning to the power save mode, the wireless terminal sets the power mode flag to "1" and transmits a data packet. When transitioning to the active mode, the radio terminal sets the power mode flag to "0" and transmits the data packet. Send a packet.

Also, the radio terminal notifies the radio base station of the start and stop cycles of the receiver during operation in the power save mode in advance. When receiving a data packet addressed to a wireless terminal operating in the power save mode, the wireless base station buffers the data packet, and stores the data packet at a timing when the receiver of the destination wireless terminal is activated. Perform packet transmission.

In this embodiment as well, data packets can be transferred from a wireless terminal to another wireless terminal by the direct transfer method. However, data packets can be transferred to a wireless terminal operating in the power save mode by the direct transfer method. When the data packet is transmitted, the transmission is performed at the timing when the receiver is stopped, and there is a high possibility that the transmission will not be completed. Therefore, in this embodiment, as shown in FIG. 24, in addition to the MAC address of the wireless terminal to which the direct transfer method can be applied, each wireless terminal can determine whether the wireless terminal is operating in the power save mode. Flags are also registered directly in the transfer table.

FIGS. 25 and 26 are flowcharts showing the operation of receiving a data packet by the wireless terminal in the present embodiment. The flow of this receiving operation is substantially the same as the flow of the data packet receiving operation of the wireless terminal according to the second embodiment (FIG. 13). However, since each wireless terminal operates not only in the active mode but also in the power save mode, new steps S431B and S432B are added to the flow of FIG. 13 described above. Other steps are the same as those in FIG. For these, the same step numbers as those used in FIG. 13 are used.

The main points of the data packet receiving operation of the wireless terminal according to the flow of FIG. 25 and FIG. 26 will be described as follows.

When the wireless terminal receives a data packet whose transfer type is "00" or "01" and whose reception level is equal to or greater than the threshold value L1, it directly sends the address of the source wireless terminal of the data packet to the transfer table. (Steps S401, S402, S403, S404,
S405).

When the wireless terminal receives a data packet whose transfer type is "00" or "01" and whose reception level is less than the threshold value L2, the source wireless terminal of the data packet in the direct transfer table Delete the registration of the address (steps S401, S402, S4).
03, S406, S407, S408).

When the radio terminal receives a data packet whose transfer type is “00” or “01”,
It is determined whether or not the address of the transmission source wireless terminal of the data packet is registered in the direct transfer table (step S431B). When the address of the source wireless terminal is registered, the power mode save flag corresponding to the source wireless terminal registered in the direct transfer table is updated by the power save mode flag in the data packet. . Since such an operation is performed in each wireless terminal, when a certain wireless terminal transmits a data packet, information indicating whether the wireless terminal is operating in the power save mode has received the data packet. The information is known to each wireless terminal and registered in the direct transfer table of each wireless terminal.

The above is the contents of the processing related to the direct transfer table performed with the reception of the data packet by the wireless terminal. After finishing these processes, the wireless terminal transmits the data packet to the own station with the transfer type “00” or “1”.
It is determined whether or not the data packet is a 0 "data packet (steps S409 and S410). If the determination result is affirmative, an ACK signal is transmitted and the data packet is delivered to an upper layer (step S412). The processing after step S409 is not different from the second embodiment.

Next, FIG. 27 is a flowchart showing a data packet transmission operation of the wireless terminal in this embodiment. The flow of this transmission operation is almost the same as the flow of the data packet transmission operation of the wireless terminal in the first embodiment (FIG. 5). However, since each wireless terminal operates not only in the active mode but also in the power save mode, a new step S231B is added to the flow of FIG. 5 described above. The other steps are the same as those in FIG. For these, the same step numbers as those used in FIG. 5 are used.

The operation of transmitting a data packet by the wireless terminal in this embodiment will be described below with reference to the flow chart of FIG. That is, when a data packet to be transferred to another wireless terminal occurs, the wireless terminal determines whether an address corresponding to the destination wireless terminal of the data packet is directly registered in the transfer table (Step S).
202). If the address corresponding to the destination wireless terminal is registered in the direct transfer table, the contents of the power save mode flag corresponding to the destination wireless terminal are read from the direct transfer table, and the power save mode flag is set to “0”. Is determined. If the power save mode flag is “0”, that is, if the destination wireless terminal is operating in the active mode, the transfer of the data packet by the direct transfer method is attempted (step S
203 to S209), and if this fails, the transfer is performed by the relay transfer method (steps S210 to S21).
6). On the other hand, when the power save mode flag is “1”, that is, when the destination wireless terminal is operating in the power save mode, the transfer by the relay transfer method is executed without any attempt of the transfer by the direct transfer method. (Steps S210 to S216). Note that the transfer by the direct transfer method (steps S203 to S209) and the transfer by the relay transfer method (steps S210 to S216) are the same as those already described in the first embodiment, and a description thereof will be omitted. I do.

In this embodiment, the operation when the radio base station relays the data packet is the same as that in the case of the first embodiment (see FIG. 6 described above), and the description is omitted.

Next, FIG. 28 and FIG. 29 are operation sequence diagrams showing an operation example of the present embodiment. In this operation example, when transitioning from the active mode to the power save mode, the wireless terminal A transmits a data packet prior to the transition. This data packet has the power save mode flag set to "1" and the transfer type set to "01" because the source wireless terminal A is about to transition to the power save mode. When receiving the data packet, the wireless base station transmits an ACK signal to the wireless terminal A, and the wireless terminal A transmits the ACK signal to the wireless terminal A.
The reception of the signal recognizes the successful transmission of the data packet.

[0220] In this operation example, the data packet transmitted from the wireless terminal A is received by the wireless terminal B. Here, the address of the wireless terminal A is registered in the direct transfer table of the wireless terminal B. When the reception level of the data packet is equal to or higher than the threshold L2, the wireless terminal B sets the power save mode flag corresponding to the transmission source wireless terminal A of the data packet in the direct transfer table to the power save mode included in the data packet. Update by the flag (= “1”). The data packet is discarded because it is not addressed to the wireless terminal B.

Thereafter, in the wireless terminal B, the wireless terminal A
A data packet to be transferred to the destination is generated. In this operation example, since the MAC address of the destination wireless terminal A is registered in the direct transfer table of the wireless terminal B, the wireless terminal B
Determines whether the power mode save flag corresponding to the destination wireless terminal A registered in the direct transfer table is “1”. In this case, since the power mode flag is “1”, the wireless terminal B transmits the data packet with the destination address set to the MAC address of the wireless terminal A and the transfer type set to “01”. Upon receiving this data packet, the wireless base station transmits an ACK signal to the source wireless terminal B. The wireless terminal B recognizes that the data packet has been successfully transmitted by receiving the ACK signal.

Here, the radio base station recognizes that radio terminal A is operating in the power save mode, and starts and stops the receiver of radio terminal A operating in the power save mode. Knows the cycle of Therefore,
The wireless base station receives the wireless terminal A received from the wireless terminal B.
Buffer the data packet addressed to the
The data packet is transmitted at the timing when the receiver is activated. Upon receiving this data packet, the wireless terminal A delivers it to the upper layer.

F. Fifth Embodiment This embodiment is an embodiment of the invention according to claim 13. In this embodiment, the format of a wireless packet exchanged between a wireless terminal and a wireless terminal and between a wireless terminal and a wireless base station is as shown in FIG. The operation of receiving a data packet by the wireless terminal is the same as that in the fourth embodiment (FIGS. 25 and 26).

FIGS. 30 and 31 show the flow of the data packet transmission operation performed by the wireless terminal in this embodiment. In the flow of the transmission operation, new steps S241C to S247C are added to the flow of the transmission operation in the fourth embodiment (FIG. 27). Other steps are not different from those in the fourth embodiment. For such a step, see FIG.
Use the same step numbers as used in.

When the source wireless terminal intends to transfer a data packet to another wireless terminal, the destination wireless terminal is directly registered in the transfer table, and
The power save mode flag of the destination wireless terminal is “0”
In the case of the active mode, the source wireless terminal first selects the direct transfer method (steps S201, S202, S231B, S203).

Next, the source wireless terminal determines whether or not the destination wireless terminal is registered in the authentication success table (step S241C). Here, in the authentication success table, addresses of wireless terminals that have been successfully authenticated in the past are registered. The operation of registering the address of the wireless terminal in the authentication success table will be described later.

When the result of the determination in step S241C is "Y
If it is "ES", the source wireless terminal immediately transfers the data packet to the destination wireless terminal by the direct transfer method (steps S204 to S209).

On the other hand, if the decision result in the step S241C is "NO", the wireless terminal determines whether or not the destination wireless terminal is registered in the authentication rejection table (step S242C). Here, in the authentication rejection table, addresses of wireless terminals whose authentication has been rejected in the past are registered. The operation of registering the address of the wireless terminal in the authentication rejection table will be described later.

When the result of the determination in step S242C is “Y
In the case of "ES", the wireless terminal executes a process for transmitting a data packet by the relay transfer method (steps S210 to S216).

On the other hand, if the decision result in the above step S242C is "NO", the wireless terminal transmits an authentication request to the destination wireless terminal (step S243C). Then, it is determined whether or not this authentication is successful (step S2).
44C) If the authentication is successful, the address of the destination wireless terminal is registered in the authentication success table (step S20).
4), execute a process for transmitting a data packet by the direct transfer method (steps S204 to S209). On the other hand, if the authentication has not been successful, it is determined whether the authentication has been rejected (step S246C). And if the authentication is not rejected, the wireless terminal
A process for transmitting a data packet by the relay transfer method is executed (steps S210 to S216). If the authentication is rejected, the address of the destination wireless terminal is registered in the authentication rejection table (step S247).
C), a process for transmitting the data packet by the relay transfer method is executed (steps S210 to S216).

According to the present embodiment, if the authentication is not successful, the packet is transferred by the relay transfer method, so that the packet directly transferred to the unauthenticated destination wireless terminal is discarded on the destination wireless terminal side. That situation can be avoided. Further, according to the present embodiment, for a wireless terminal that has been successfully authenticated in the past, the authentication can be omitted and the data packet transfer can be performed by the direct transfer method. On the other hand, there is an advantage that data packets can be transferred by the relay transfer method without performing useless authentication procedures.

FIGS. 32 and 33 are operation sequence diagrams each showing an operation example of the present embodiment. Hereinafter, the operation of the present embodiment will be described more specifically with reference to these drawings.

First, in the operation example shown in FIG. 32, the direct transfer table of the wireless terminal A stores the MA of the destination wireless terminal B.
The C address is registered, no authentication has been performed between the wireless terminal A and the wireless terminal B, and no authentication has been rejected.

For this reason, the wireless terminal B
When a data packet to be transferred to the destination is generated, the wireless terminal A sends an authentication request to the wireless terminal B. When performing the authentication, the wireless terminal B sends an authentication result notification to the effect that the authentication is permitted to the wireless terminal A, and registers the address of the wireless terminal A in the authentication permission table.

Upon receiving the authentication result notification, wireless terminal A registers the address of wireless terminal B in the authentication permission table.

Thereafter, when a data packet to be transferred to the wireless terminal B occurs at the wireless terminal A, the wireless terminal A skips the authentication and transfers the data packet to the wireless terminal B by the direct transfer method.

Upon receiving this data packet, radio terminal B determines whether or not the transmission source radio terminal A is a radio terminal registered in the authentication permission table.
If "S", the base station transmits an ACK signal to the wireless terminal A, and delivers the data packet to the upper layer.

Wireless terminal A receives the ACK signal from wireless terminal B, thereby recognizing that the transmission of the data packet has been successful.

Next, an operation example shown in FIG. 33 will be described. Also in this operation example, the MAC address of the destination wireless terminal B is registered in the direct transfer table of the wireless terminal A, and no authentication has been performed between the wireless terminal A and the wireless terminal B. Authentication has never been denied.

For this reason, the wireless terminal A
When a data packet to be transferred to the destination is generated, the wireless terminal A sends an authentication request to the wireless terminal B. However, the wireless terminal B in this operation example sends an authentication result notification to the wireless terminal A to reject the authentication.

Upon receiving the authentication result notification, wireless terminal A registers the address of wireless terminal B in the authentication rejection table.

Thereafter, when a data packet to be transferred to wireless terminal B occurs at wireless terminal A, wireless terminal A transfers the data packet to wireless terminal B by the relay transfer method without performing authentication.

That is, the radio terminal A sets the destination address to the MAC address of the radio terminal B and sets the transfer type to “01”.
As a data packet. Upon receiving this data packet, the wireless base station transmits an ACK signal to the source wireless terminal A. The wireless terminal A recognizes the success of the data packet transmission by receiving the ACK signal. Further, the radio base station sets the transfer type to “10” and transmits the data packet from the radio terminal A.
When receiving the data packet, the wireless terminal B delivers the data packet to an upper layer.

The above is a characteristic operation example in the present embodiment. Note that, in the present embodiment, when deleting the registration of the wireless terminal registered in the direct transfer table, the wireless terminal does not delete the registration of the wireless terminal in the authentication success table or the authentication rejection table. Therefore, for example, even when an obstacle between wireless terminals frequently moves and direct registration and deregistration of the direct transfer table frequently occur, this does not change the registration state of the authentication success table or the authentication rejection table. . For this reason, if the registration in the direct transfer table is deleted for a certain wireless terminal and then the wireless terminal is again registered in the direct transfer table, if the authentication has been successful in the past, It is possible to directly transfer to the wireless terminal without performing authentication again. If a huge number of wireless terminals are expected to be registered in the authentication success table or the authentication rejection table, it is necessary to take measures. In this case, for example, when the total number of registered wireless terminals in the authentication success table or the like is likely to exceed the maximum number of registrations, the oldest one may be deleted.

G. Sixth Embodiment In a wireless packet transfer system, there is a case where a broadcast is performed in which data packets having the same content are simultaneously transferred from a wireless terminal to all other wireless terminals. In the present embodiment, the present invention is applied to a wireless packet transfer system in which such a broadcast is performed.
This is an embodiment of the invention according to claim 14. In this embodiment, the format of a wireless packet exchanged between a wireless terminal and a wireless base station is as shown in FIG.

FIGS. 34 and 35 show the flow of the data packet receiving operation performed by the wireless terminal in this embodiment. This transmission operation flow is different from the transmission operation flow (FIGS. 25 and 26) in the fourth embodiment.
A new step S451D is added. Other steps are not different from those in the fourth embodiment. For such steps, the same step numbers as those used in FIGS. 25 and 26 are used.

In this embodiment, the wireless terminal determines in step S409 whether the destination address of the received data packet matches the address of its own station.
If the result of this determination is "NO", it is determined whether or not the data packet is a broadcast packet (step S451D). If the data packet is a broadcast packet, the data packet is delivered to an upper layer (step S41).
2) If the packet is not a broadcast packet, the data packet is discarded (step S413). Other operations are not different from those of the fourth embodiment.

Next, the flow of the data packet transmission operation performed by the wireless terminal in this embodiment will be described with reference to FIGS.
FIG. The flow of the transmission operation is the one in which a new step S251D is added to the flow of the transmission operation (FIGS. 30 and 31) in the fifth embodiment. The other steps are the same as those in the fifth embodiment. For such steps, the same step numbers as those used in FIGS. 30 and 31 are used.

In this embodiment, when attempting to transfer a data packet, the wireless terminal determines whether or not to perform the transfer as a broadcast (step S25).
1D). If the result of this determination is "NO", the operation proceeds to step S201, and thereafter, the same processing as in the fifth embodiment is executed. On the other hand, if the decision result in the step S251D is "YES", the data packet is broadcast by the relay transfer method (steps S210 to S216).

FIG. 38 is an operation sequence diagram showing a specific operation example of the present embodiment. As shown in FIG. 38,
When transmitting a data packet by broadcast, the wireless terminal A sets the transfer type to “01”, sets the destination address to information corresponding to broadcast, and transmits the data packet. Upon receiving this data packet, the radio base station sends back an ACK signal and transmits the data packet with the transfer type set to “10”. When all the wireless terminals accommodated in the wireless base station receive this data packet, they recognize that the data packet is a broadcast packet,
Deliver to upper layer.

H. Seventh Embodiment In the present embodiment, when a wireless terminal is out of the service area of a wireless base station, a data packet can be transferred to a desired wireless terminal by a direct transfer method. It is an embodiment of the invention. This embodiment can be applied to any of the above-described embodiments, but a case where the present embodiment is applied to the sixth embodiment will be described below as an example.

In the present embodiment, the radio base station transmits a broadcast signal periodically. When the wireless terminal receives the broadcast signal correctly, it determines that the own station is within the service area of the wireless base station. Judge that you are out of service area.

In this embodiment, the operation flow of the data packet transmission operation performed by the wireless terminal is shown in FIGS.
Shown in This transmission operation flow is the same as the transmission operation flow (FIGS. 36 and 37) in the sixth embodiment except that a new step S261E is added. The other steps are the same as those in the sixth embodiment. For such steps, the same step numbers as those used in FIGS. 36 and 37 are used.

In this embodiment, when attempting to transfer a data packet, the wireless terminal determines whether or not its own station is within the service area of the wireless base station (step S261E).

When the own station is out of the service area (when the judgment result in step S261E is "NO") or when the own station is in the service area and the destination wireless terminal is directly registered in the transfer table. (If the determination result of step S261E and step S202 is “Y
ES ”), an attempt is made to transfer the data packet to the destination wireless terminal by the direct transfer method (step S20).
3-S20).

On the other hand, the own station is within the service area, and
If the destination wireless terminal is not registered in the direct transfer table (if the determination result in step S261E is “YES” and the determination result in step S202 is “NO”), the destination wireless terminal by the relay transfer method is used. Execute data packet transfer to the terminal (steps S210 to S2)
16). Other points are the same as in the sixth embodiment.

I. Eighth Embodiment The present embodiment is intended for convenience when a wireless terminal performs switching (handoff) of a wireless base station, and is an embodiment of the invention according to claim 16. This embodiment can be applied to any of the embodiments described above.

FIG. 41 is a flowchart showing the operation in the case where the wireless terminal performs handoff in the present embodiment. As shown in this figure, when starting the handoff, the wireless terminal selects a wireless base station that is a new destination (step S501). Here, as a trigger of the handoff start, for example, a case where a notification signal from the wireless base station is not received j times in succession can be set. As a method for selecting a new destination radio base station, for example, monitoring all radio channel frequencies in the radio packet transfer system for a certain period of time and selecting a radio base station with the highest reception level of the broadcast signal is performed. A method can be adopted. Next, the wireless terminal deletes the registration of all wireless terminals in the direct transfer table (step S50).
2).

According to the present embodiment, even when a wireless terminal has directly transferred to another wireless terminal before handoff,
After the handoff, the packet transfer to the other wireless terminal is performed by the relay transfer method.

J. Phys. Ninth Embodiment This embodiment is an embodiment of the present invention according to claim 17, in which the present invention is applied to a wireless packet transfer system that transfers packets by a fragment division transmission method. This embodiment can be applied to any of the embodiments described above.

FIG. 42 shows an operation flow of a data packet transmission operation performed by the wireless terminal in this embodiment. When transmitting a data packet, the wireless terminal determines whether to transfer the data packet by the direct transfer method or the relay transfer method (step S601). The specific process for determining the transfer method is as described in each embodiment.

If the data packet is to be transferred by the direct transfer method, the wireless terminal determines whether or not the packet length of the data packet exceeds the fragment threshold for direct transfer (step S60).
2) If it exceeds, the data packet is divided so that the packet length is equal to or less than the fragment threshold (step S603).

On the other hand, if the data packet is to be transferred by the relay transfer method, the wireless terminal determines whether or not the packet length of the data packet exceeds the fragment threshold for relay transfer (step S60).
4) If it exceeds, the data packet is divided so that the packet length is equal to or less than the fragment threshold (step S605).

After the above processing, the transfer type of the data packet is set to “00” when the direct transfer method is used, and the transfer type of the data packet is set to “01” when the relay transfer method is used. Is performed (step S606).

The specific processing of the direct transfer method and the relay transfer method is as described in each embodiment.

According to the present embodiment, the fragment threshold for direct transfer is set to a value suitable for the transmission path between wireless terminals, and the fragment threshold for relay transfer is set between the wireless terminal and the wireless base station. The value can be set to a value suitable for the transmission path to and from the station, whereby a high throughput can be obtained.

K. Tenth Embodiment This embodiment is an embodiment in which the present invention is applied to a wireless packet transfer system that transfers packets by the RTS / CTS random access method, and is an embodiment according to claim 18. This embodiment can be applied to any of the embodiments described above.

FIG. 43 shows an operation sequence of data packet transfer by the RTS / CTS random access method. In FIG. 43, the source wireless terminal A adds a source address and a packet length to the RTS signal. When the transfer is performed by the relay transfer method, the transfer type is “01”.
Is added to the RTS signal and transmitted to the radio base station, and when the transfer is performed by the direct transfer method, the transfer type “00”
It is added to the S signal and transmitted to the destination wireless terminal. In the operation example shown in FIG. 43, the wireless terminal A attaches the transfer type “00” to the RTS signal and transmits it to the wireless terminal B in order to perform the transfer by the direct transfer method.

When wireless terminal B receives the RTS signal whose transfer type is “00”, it uses the address of wireless terminal A as the transmission source of the RTS signal as the permission address and includes the packet length given to the RTS signal. Transmit the CTS signal.
Note that when the RTS signal whose transfer type is "01" is received by the radio base station, the same CTS signal is transmitted by the radio base station.

Upon receiving the CTS signal, each wireless terminal determines whether or not the permitted address of the CTS signal matches the address of its own station.

In the example shown in FIG. 43, the wireless terminal A, which is the source of the RTS signal, confirms that the permitted address of the CTS signal matches the address of its own station, and sets the transfer type to “00”. A data packet addressed to the wireless terminal B is transmitted. Upon receiving the data packet, the wireless terminal B transmits an ACK signal to the wireless terminal A. The wireless terminal A recognizes the success of the transmission by receiving the ACK signal.

On the other hand, since the other wireless terminal C does not match the permitted address of the CTS signal with the address of its own station, the other wireless terminal C has a period corresponding to the packet length included in the CTS signal.
Does not transmit data packets and RTS signals.

The above is the outline of the operation of the data packet transfer by the RTS / CTS random access method. According to this method, the problem of so-called hidden terminals can be solved.

FIG. 44 is a flowchart showing a data packet transmission operation of the wireless terminal according to the present embodiment.
In this embodiment, when a data packet to be transferred occurs, the wireless terminal sets a retry counter to “1” (step S701), and determines whether to perform the data packet transfer by the direct transfer method or the relay transfer method. (Step S702).

When it is determined that the data packet transfer is to be performed by the direct transfer method, it is determined whether or not the packet length of the data packet exceeds the RTS threshold value for direct transfer (step S703). "", The process proceeds to step S705, and if "NO", the process proceeds to step S710. On the other hand, if it is determined that the data packet transfer is to be performed by the relay transfer method, it is determined whether or not the packet length of the data packet exceeds the RTS threshold for relay transfer (step S704), and the determination result is “YES”. In the case of, the process proceeds to step S705, and in the case of “NO”, the process proceeds to step S710.

Next, the packet length exceeds the RTS threshold value for direct transfer or the RTS threshold value for relay transfer, and step S7
When the process proceeds from step S03 or S704 to step S705, the wireless terminal transmits an RTS signal. Here, in the case of direct transfer, the transfer type “00” is added to the RTS signal and transmitted, and in the case of relay transfer, the transfer type “01” is added to the RTS signal and transmitted.

When the transmission of the RTS signal is completed, the CTS
It is determined whether a signal has been received (step S70).
6). If the CTS signal is not received, it is determined whether the value of the retry counter is less than a predetermined value K (step S707). If the value is less than K, the retry counter waits for a randomly determined time and sets the retry counter. Increase by "1" (step S708), and again RTS
The signal transmission (step S705) is repeated. Also, C
Although the same applies to the case where the TS signal is received and the case where the permitted address included in the CTS signal does not match the address of the own station (step S709),
In this case, transmission of the RTS signal is suspended for a time corresponding to the packet length included in the CTS signal.

After the transmission of the RTS signal, if the CTS signal is received and the destination address included in the CTS signal matches the address of the own station, step S702 of the direct transfer method or the relay transfer method is performed. The data packet is transmitted by the transfer method determined in (1) (step S710).

When the value of the retry counter reaches the predetermined value K without receiving the CTS signal addressed to the own station,
The data packet is discarded (step S711).

The above is the data packet transmission operation of the wireless terminal in the present embodiment. According to the present embodiment, since the RTS threshold is different for the case of direct transfer and the case of relay transfer, the RTS threshold for direct transfer is set to a value suitable for the transmission path between wireless terminals, By setting the RTS threshold for relay transfer to a value suitable for the transmission path between the wireless terminal and the wireless base station, high throughput can be obtained.

[0281]

According to the first to sixteenth aspects of the present invention, there is a low possibility that the packet transfer by the direct transfer method ends in failure, while the packet transfer by the direct transfer method is performed as much as possible. This makes it possible to obtain high throughput, and to perform packet transfer in a transfer time as short as possible.

(2) According to the twelfth aspect, when the destination wireless terminal is operating in the power save mode, the relay transfer is performed even if the destination wireless terminal is directly registered in the transfer table. The method is applied. Therefore, according to the present invention, it is possible to avoid a situation in which a packet is transferred to the destination wireless terminal operating in the power save mode by the direct transfer method and a failure occurs, and the throughput can be improved. can get.

(3) The invention according to claim 13 solves the problem that when a destination wireless terminal rejects authentication and sends a packet by the direct transfer method, the packet is discarded on the destination wireless terminal side. It is possible to obtain an effect that a high throughput can be obtained and packet transfer can be performed in a packet transfer time as short as possible.

(4) According to the fourteenth aspect, packet transfer can be performed by relay transfer even to a wireless terminal that cannot receive a broadcast packet when direct transfer is performed. Can be increased.

(5) According to the invention of claim 15, when the wireless terminal is located outside the service area of the wireless base station, whether or not the destination wireless terminal is directly registered in the transfer table is determined. Instead, since the packet is transferred by the direct transfer method, useless packet transfer by the relay transfer method can be prevented, and the effect of improving the throughput and shortening the packet transfer time can be obtained.

(6) According to the sixteenth aspect, after the switching of the radio base station, first, the packet transfer is performed by the relay transfer method, so that the direct transfer after the switching of the radio base station is performed. It is possible to prevent the occurrence of a failure, and to improve the throughput and shorten the packet transfer time.

(7) According to the seventeenth aspect, a fragment threshold suitable for each of the relay transfer method and the direct transfer method can be used, thereby improving the throughput. The effect that it can be obtained is obtained.

(8) According to the eighteenth aspect, an RTS threshold suitable for each of the relay transfer method and the direct transfer method can be used, so that the throughput can be improved. The effect that it can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a network to which each embodiment of the present invention is applied.

FIG. 2 is a diagram illustrating a format of a wireless packet exchanged between a wireless terminal and a wireless terminal or between a wireless terminal and a wireless base station in the first embodiment of the present invention.

FIG. 3 is a flowchart showing a data packet receiving operation performed by the wireless terminal in the embodiment.

FIG. 4 is a diagram illustrating contents of a direct transfer table according to the embodiment;

FIG. 5 is a flowchart showing a data packet transmission operation performed by the wireless terminal in the embodiment.

FIG. 6 is a flowchart showing a data packet relay operation performed by the wireless base station in the embodiment.

FIG. 7 is an operation sequence diagram illustrating an operation example in which the wireless terminal directly transfers a data packet to a wireless terminal registered in a transfer table in the embodiment.

FIG. 8 is an operation sequence diagram showing an operation example in which the wireless terminal directly registers another wireless terminal in the transfer table in the embodiment.

FIG. 9 is an operation sequence diagram illustrating an operation example in which the wireless terminal transfers a data packet to a wireless terminal that is not directly registered in the transfer table in the embodiment.

FIG. 10 is an operation sequence diagram showing an operation example in a case where a wireless terminal directly transfers a data packet to a wireless terminal registered in a transfer table in the same embodiment, but a destination wireless terminal cannot receive the data packet. .

FIG. 11 is a diagram illustrating an operation when each wireless terminal accommodated in each adjacent wireless base station performs data packet transfer in the embodiment.

FIG. 12 is an operation sequence diagram showing an operation of data packet transfer performed between a wireless terminal and a wired terminal in the embodiment.

FIG. 13 is a flowchart showing a data packet receiving operation performed by a wireless terminal according to the second embodiment of the present invention.

FIG. 14 shows two wireless terminals registering the other wireless terminal in each of the direct transfer tables in the embodiment, but the other wireless terminal transmits a data packet transmitted by one of the wireless terminals below a threshold L2. FIG. 9 is an operation sequence diagram illustrating an operation example when reception is performed at a reception level.

FIG. 15 is a flowchart (first half) illustrating a data packet receiving operation performed by the wireless terminal according to the third embodiment of the present invention.

FIG. 16 is a flowchart (second half) illustrating a data packet receiving operation performed by the wireless terminal in the embodiment.

FIG. 17 is a flowchart showing a data packet transmission operation performed by the wireless terminal in the embodiment.

FIG. 18 is a flowchart showing an operation when a monitoring timer times out in the embodiment.

FIG. 19 is an operation sequence diagram illustrating an operation example in which the wireless terminal directly transfers a data packet to the wireless terminal registered in the transfer table in the embodiment.

FIG. 20 is an operation sequence diagram illustrating an operation example in which the wireless terminal directly registers another wireless terminal in the transfer table in the embodiment.

FIG. 21 is a diagram illustrating an example in which the wireless terminal directly transfers a data packet addressed to the wireless terminal registered in the transfer table.
It is an operation | movement sequence diagram which shows the example of an operation at the time of receiving by the reception level less than 2.

FIG. 22 is an operation sequence diagram showing an operation example when the wireless terminal is directly registered in the transfer table and the monitoring timer times out in the embodiment.

FIG. 23 is a diagram showing a format of a wireless packet exchanged between a wireless terminal and a wireless terminal or between a wireless terminal and a wireless base station in the fourth embodiment of the present invention.

FIG. 24 is a diagram illustrating contents of a direct transfer table in the embodiment.

FIG. 25 is a flowchart (first half) showing a data packet receiving operation performed by the wireless terminal in the embodiment.

FIG. 26 is a flowchart (second half) showing a data packet receiving operation performed by the wireless terminal in the embodiment.

FIG. 27 is a flowchart showing a data packet transmission operation performed by the wireless terminal in the embodiment.

FIG. 28 is an operation sequence diagram (first half) illustrating an operation example when the wireless terminal transits from the active mode to the power save mode in the embodiment.

FIG. 29 is an operation sequence diagram (second half) illustrating an operation example when the wireless terminal transits from the active mode to the power save mode in the same embodiment.

FIG. 30 is a flowchart (first half) illustrating a data packet transmission operation performed by the wireless terminal according to the fifth embodiment of the present invention.

FIG. 31 is a flowchart (second half) illustrating a data packet transmission operation performed by the wireless terminal in the embodiment.

FIG. 32 is an operation sequence showing an operation example when the wireless terminal B permits authentication when the wireless terminal B is registered in the direct transfer table of the wireless terminal A and the wireless terminal B is not authenticated in the embodiment. FIG.

FIG. 33 is an operation sequence showing an operation example in a case where the wireless terminal B is registered in the direct transfer table of the wireless terminal A and the wireless terminal B is not authenticated, and the wireless terminal B rejects authentication in the embodiment. FIG.

FIG. 34 is a flowchart (first half) illustrating a data packet receiving operation performed by a wireless terminal according to the sixth embodiment of the present invention.

FIG. 35 is a flowchart (second half) illustrating a data packet receiving operation performed by the wireless terminal in the same embodiment.

FIG. 36 is a flowchart (first half) showing a data packet transmission operation performed by the wireless terminal in the embodiment.

FIG. 37 is a flowchart (second half) illustrating a data packet transmission operation performed by the wireless terminal in the same embodiment.

FIG. 38 is an operation sequence diagram showing an operation example when broadcasting is performed in the embodiment.

FIG. 39 is a flowchart (first half) illustrating a data packet transmission operation performed by a wireless terminal according to the seventh embodiment of the present invention.

FIG. 40 is a flowchart (second half) illustrating a data packet transmission operation performed by the wireless terminal in the same embodiment.

FIG. 41 is a flowchart showing an operation at the time of handoff performed by the wireless terminal according to the eighth embodiment of the present invention.

FIG. 42 is a flowchart illustrating a data packet transmission operation performed by a wireless terminal according to the ninth embodiment of the present invention.

FIG. 43 is an operation sequence diagram showing an operation example of data packet transfer by the RTS / CTS random access method to which the tenth embodiment of the present invention is applied;

FIG. 44 is a flowchart showing a data packet transmission operation performed by the wireless terminal in the embodiment.

FIG. 45 is a diagram illustrating a direct transfer method and a relay transfer method.

[Explanation of symbols]

 Reference Signs List 10 wireless base station 11 accommodation terminal table 1-4, A, B, C wireless terminal 20, Z wired terminal 30 Ethernet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Takanashi 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Masahiro Morikura 3-19, Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation

Claims (18)

[Claims] When a wireless terminal transmits a packet to another wireless terminal, the source wireless terminal transmits a packet to a wireless base station, and the wireless base station sends the packet to the destination wireless terminal. Selecting either a relay transfer method of transmitting a packet, or a direct transfer method of transmitting the packet directly to the destination wireless terminal by the source wireless terminal,
The packet is transferred by the selected method, and the destination wireless terminal and the wireless base station transmit a response signal when the packet is received without error, and the source wireless terminal transmits the packet for a certain period after the transmission of the packet. If the response signal is received within the packet, it is determined that the packet transmission is completed. If the response signal is not received within a certain period after the transmission of the packet, it is determined that the packet transmission is incomplete and the packet is retransmitted. In the wireless packet transfer method, the wireless terminal comprises: a. Storing a direct transfer table identifying wireless terminals to which the direct transfer method can be applied; b. When transferring a packet to any other wireless terminal, if the destination wireless terminal is not registered in the direct transfer table, transfer the packet by the relay transfer method, and the destination wireless terminal If it is registered in the table, transfer the packet by the direct transfer method, c. Based on the reception status of a packet transmitted to an arbitrary wireless terminal at its own station, it is determined whether or not the transmission source wireless terminal of the packet satisfies a registration condition for being registered in the direct transfer table. If the registration condition is satisfied, register the source wireless terminal in the direct transfer table; d. At least one of a transmission result when the own station transmits a packet addressed to the wireless terminal registered in the direct transfer table or a reception state when the own station receives a packet transmitted from any wireless terminal to the wireless terminal. Based on the, it is determined whether or not a registration cancellation condition for canceling the registration of the wireless terminal in the direct transfer table is satisfied, and if the registration cancellation condition is satisfied, registration of the wireless terminal in the direct transfer table is performed A wireless packet transfer method characterized by deleting. 2. The wireless terminal transmits a packet transmitted to an arbitrary wireless terminal to a same source wireless terminal as a threshold L.
When receiving at least one reception level and receiving m times consecutively, the wireless terminal that is the transmission source determines that the registration condition is satisfied, and registers the wireless terminal in the direct transfer table. Item 2. The wireless packet transfer method according to Item 1. 3. The wireless terminal transmits a packet transmitted to an arbitrary wireless terminal to a threshold value L1 at the transmission source wireless terminal.
At the above reception level, when receiving Q1 times out of P1 times (P1 ≧ Q1), it is determined that the wireless terminal that is the transmission source satisfies the registration condition, and the wireless terminal is registered in the direct transfer table. The wireless packet transfer method according to claim 1, wherein: 4. The wireless terminal transmits a packet transmitted to an arbitrary wireless terminal to a same source wireless terminal as a threshold L.
Q1 during m1 times or P1 times at one or more reception levels
2. The wireless terminal as the transmission source, when receiving (P1 ≧ Q1) times, determines that the wireless terminal satisfies the registration condition, and registers the wireless terminal in the direct transfer table. Wireless packet transfer method. 5. The wireless terminal performs packet transfer according to the direct transfer method, and when the same source wireless terminal determines that packet transmission is not completed continuously m2 times, the wireless terminal that is the destination determines the packet transmission failure. The wireless packet transfer method according to any one of claims 1 to 4, wherein it is determined that the registration cancellation condition is satisfied, and the registration of the wireless terminal in the direct transfer table is canceled. 6. The wireless terminal performs packet transfer according to the direct transfer method, and uses the same source wireless terminal to perform P2
If it is determined that the packet transmission is incomplete Q2 times (P2 ≧ Q2), it is determined that the destination wireless terminal satisfies the registration cancellation condition, and the registration of the wireless terminal in the direct transfer table is canceled. The wireless packet transfer method according to any one of claims 1 to 4, wherein: 7. The wireless terminal performs packet transfer according to the direct transfer method, and determines that the same source wireless terminal has determined that packet transmission is incomplete m2 times or Q2 times out of P2 times (P2 ≧ Q2). In this case, it is determined that the destination wireless terminal satisfies the registration cancellation condition, and the registration of the wireless terminal in the direct transfer table is canceled. The wireless packet transfer method according to the paragraph. 8. The wireless terminal transmits a packet transmitted to an arbitrary wireless terminal by a wireless terminal registered in the direct transfer table to the same transmission source wireless terminal at a reception level less than a threshold L2 continuously m3 times. Upon reception, it is determined that the wireless terminal that is the source satisfies the registration cancellation condition,
8. The wireless packet transfer method according to claim 1, wherein registration of the wireless terminal in the direct transfer table is deleted. 9. The wireless terminal, according to claim 1, wherein the wireless terminal registered in the direct transfer table transmits a packet addressed to an arbitrary wireless terminal at a reception level less than a threshold L2 at the same source wireless terminal during P3 times. The method according to claim 1, wherein upon receiving Q3 times (P3 ≧ Q3), it is determined that the wireless terminal as the transmission source satisfies the registration cancellation condition, and the registration of the wireless terminal in the direct transfer table is canceled. 1 to
The wireless packet transfer method according to claim 7. 10. The wireless terminal transmits a packet transmitted to an arbitrary wireless terminal by a wireless terminal registered in the direct transfer table to the same source wireless terminal at a reception level less than a threshold L2 for m3 consecutive times. Or P3 times Q3 times (P
3 ≧ Q3) upon reception, determine that the transmission source wireless terminal satisfies the deregistration condition, and delete the registration of the radio terminal in the direct transfer table. The wireless packet transfer method according to claim 1. 11. The wireless terminal does not receive a packet transmitted to an arbitrary wireless terminal by a wireless terminal registered in the direct transfer table for a certain period of time, and transmits a packet to the registered wireless terminal. And when the packet transmission is not completed once, the registered wireless terminal satisfies the deregistration condition, and deregisters the wireless terminal in the direct transfer table. The wireless packet transfer method according to any one of claims 1 to 10, wherein 12. The wireless terminal notifies the wireless base station in advance of a start and stop cycle of the receiver in a power save mode in which the start and stop of the receiver are periodically repeated. When switching from the active mode to maintain the machine in the active state to the power save mode, or conversely, when switching from the power save mode to the active mode, the wireless base station is notified of mode switching, and If the destination wireless terminal is in the power save mode when transferring a packet to the wireless terminal, regardless of whether the destination wireless terminal is registered in the direct transfer table,
The wireless packet transfer method according to claim 1, wherein the transfer of the packet is performed by the relay transfer method. 13. The wireless terminal, when transferring a packet to another wireless terminal, performs authentication with the other wireless terminal, and if the authentication is not successful, the other wireless terminal transmits the packet to the other wireless terminal. 13. The packet transfer method according to claim 1, wherein packet transfer to the other wireless terminal is performed by the relay transfer method regardless of whether the packet is registered in the direct transfer table. Wireless packet transfer method. 14. The wireless terminal according to claim 1, wherein, when transferring a packet by broadcasting, the wireless terminal transfers the packet by the relay transfer method. The wireless packet transfer method according to the above. 15. The wireless terminal detects whether the wireless terminal is located within a service area of the wireless base station or out of the service area. If the wireless terminal is located outside the service area of the wireless base station, the direct transfer is performed. The wireless packet transfer method according to any one of claims 1 to 14, wherein packet transfer is performed by a method. 16. The wireless terminal according to claim 1, wherein the wireless terminal deletes registration of all wireless terminals in the direct transfer table in accordance with switching of a wireless base station in which the wireless terminal is located. The wireless packet transfer method according to claim 1. 17. A wireless packet communication is performed between a wireless base station and a plurality of wireless terminals. When the wireless terminal transmits a packet, if the packet length of the packet exceeds a preset fragmentation threshold, the packet length is reduced. In the wireless packet transfer method of dividing and transmitting the packet so as to be equal to or less than the fragment threshold, the wireless terminal transmits a packet to the wireless base station, and the wireless base station transmits the packet to a destination wireless terminal. Wherein a different fragmentation threshold is used for each of a case of performing a packet transfer by a relay transfer method of transmitting a packet and a case of performing a packet transfer by a direct transfer method of directly transmitting the packet to the destination wireless terminal. Packet transfer method. 18. A wireless packet communication is performed between a wireless base station and a plurality of wireless terminals, and when the wireless terminal transmits a packet, the packet length of the packet is set to a predetermined RTS.
If the threshold value is exceeded, the RTS signal is transmitted to the destination wireless terminal or the wireless base station by adding its own identifier and the packet length to the destination wireless terminal or the wireless base station, and the destination wireless terminal or the wireless base station transmits the RTS signal. In the case where the transfer of the packet by the former wireless terminal is permitted, the identifier and the packet length given to the RTS signal are added to the CTS signal as a permitted address and a reservation period and transmitted, and the RTS signal is transmitted. The wireless terminal transmits the packet when receiving a CTS signal including the address of the own station as the permission address, and is attached to the CTS signal when receiving the CTS signal not including the address of the own station as the permission address. RT until the end of the reservation period
In a wireless packet transfer method for rejecting transmission of an S signal and a packet, the wireless terminal transmits a packet to the wireless base station, and the wireless base station transmits the packet to a destination wireless terminal. A wireless packet transfer method, wherein different RTS thresholds are used for performing a transfer and a case of performing a packet transfer by a direct transfer method of directly transmitting the packet to the destination wireless terminal.